SEDI4ENTATION DURING THE TACONIC
OROGENY:
A STUDY OF LATE ORDOVICIAN
AND EARLY SILURIAN ROCKS OF THE
SIEGAS AREA, NEW BRUNSWICK
by
Terence Hamilton-Smith
Submitted in Partial Fulfillment
of the Requirements for the
Degree of Master of Science
and the
Degree of Bachelor of Science
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
June,
1969
I,
Signature of Author
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Department of Geology and
Geophysics,
May, 1969
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Certified by
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Thesis Supervisor
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Accepted by
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Chairman, Departmental
Committee on Theses
Lindgren
'JUN 2 0 1969
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ABSTRACT
The thesis area is twenty square miles in extent and is
underlain by folded sedimentary rocks.
The purpose of the
thesis is to define the sedimentary environment of an area
during the Taconic orogeny.
The Siegas area was chosen
because of its proximity to the Taconic folded belt and
because of the occurrence of sandstones of early Llandovery
age.
Detailed work was done only on the Carys Mills Formation
of Late Ordovician age and the Siegas Formation of early
Llandovery age.
No unconformity of regional significance
occurs in the thesis area.
The Carys Mills Formation is characterized by an assemblage
of thinly interbedded limestone and slate.
A model of
sedimentation is presented based on modern carbonate
deposition in the deep basin of the Black Sea.
This model
implies that the calcareous mud was mainly biogenic and was
deposited by fallout from life-supporting surface waters.
Facies changes show that the Carys Mills Formation in the
thesis area is a marginal facies of the formation as a whole
and that the surface of deposition shallowed to the north
in the direction of a source of fine-grained terriginous
sediment.
Vertical changes in the Siegas Formation were studied
by detailed graphic log analysis of one complete section.
The sedimentation of the formation consisted of two distinct
processes which occurred concurrently.
In situ deposition
of calcareous mud was essentially a continuation of the
environment of the Carys Mills Formation.
Superimposed on
this process were three distinct events of exogenic
sedimentation of sand.
The environ-nent of exogenic
sedimentation varied laterally across the thesis area from a
high-energy shelf-Zo-where quartz arenites were deposited
to a deeper basin characterized by transgressive-regressive
sequences of turbidite deposition.
Structural analysis shows that the bulk deformation of the
thesis area took place in the Acadian orogeny by the
development of a system of plane, cylindrical, tightly appressed
folds.
Older structures within the Madawaska Lake Formation
may have been developed by syndepositional folding during
the Taconic orogeny.
Relationships of the thesis area to surrounding regions
show that the Siegas Formation is laterally equivalent to
early Llandovery beds of the Carys Mills Formation to the
southeast of the thesis area.
The source area of the
Siegas Formation was probably an isolated anticlinorium in
northwestern New Brunswick composed of quartzose sandstones,
mafic volcanic rocks and salic plutonic rocks.
CONTENTS
Page
Abstract ..........
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Introduction ......
12
Acknowledgement s
12
Previous work ..
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Present work ...
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Regional setting
Local stratigraphy
15
18
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18
Madawaska Lake Formati on
21
Summary
Distribution and thickness
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Lithology
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21
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24
Age...........................
Perham
Lower
member
25
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Formation
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Distribution and thickness
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Lithology
Age
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Contact with the Siegas Formation
27
Slump
28
Upper
member
Carys Mills
Summary
structures
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Formation
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29
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30
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Distribution and thickness
Detailed
Lower
stratigraphy
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limestone member
32
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34
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Page
Middle slate member
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Upper limestone member ......... 0.*
35
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36
O* g*
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Relationship to the Madawaska Lake Formation
36
Age
37
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Facies variations
38
Stratigraphic variations ...
38
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.
Lower limestone member
38
Upper limestone member
39
Insoluble residue analysis
40
g.........
Method of analysis ......
40
Lateral variations of inso luble
residue content
42
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Limestone lithotype .........
Mineralogy
46
46
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Sedimentary structures
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47
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Faunal distribution .
*Ce00
48
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Local depositional environment
Sie gas
Formation
51
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54
.g.......
Summary
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Definition .......
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54
e
58
0....
Distribution and thickness
59
Relationship to the Carys Mills Format ion
59
Age .......................
61
EK558 section ......
Method of study
Lithotypes
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61
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61
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Limestone conglomerate
Sandstone........
Siltstone
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62
68
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78
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Limestone ............
Chert
*
79
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a
79
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Stratigraphic succession
79
Modal analyses of sandsto aes
Paleocurrent analyses ...
...
Facies variations
83
. ..
85
a......
87
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Stratigraphic variations
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Variation of sandstone co npositions
87
90
Roundness distribution an alysis .
101
Grain size distribution a nalysis ..
102
Environment of deposition ..
107
Provenance
110
Depositional history
.e.....
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Structural geology
112
.114
Summary ......
114
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Regional setting ......
Field analysis ......
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116
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118
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g.
Macroscopic features
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118
Mesoscopic features
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Stereographic analysis
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121
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.. 6 . . .
124
Procedure
Bedding
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Cleavage ...........
Tectonic interpretation ...........................
131
134
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134
Acadian orogeny
Older structures...............
e.......
135
Aspects of the regional geology ............
g.......
138
Summary
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138
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Regional stratigraphy
140
Sedimentation in the Aroostook-Matapedia belt
142
Provenance of the Siegas Formation
145
Appendix 1:
148
Summary of paleontological info rmation
148
Carys Mills Formation ...................
Siegas Formation .....
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155
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159
Appendix 2: Method of insoluble residue analysis
Appendix 3:
Vertical variation of insoluble
residue content of limestones of the
Carys Mills
Appendix 4:
Formation
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163
..........................
Analysis of clasts of a conglomerate
168
bed of the Siegas Formation
Appendix 5:
Petrographic modal analysis of
171
sandstones of the Siegas Formation
Method
of
analysis
Petrographic
Results
of
species
analysis
Grouped analysis
References
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178
181
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184
ILLUSTRATIONS
Page
Figure 1.
2.
Index map of the Siegas area, New Brunswick ..
Some tectonic features of northeastern
Maine
and vicinity
16
..........................
3.
Generalized stratigraphy of the thesis area
4.
Generalized section of the Madawaska Lake
Formation
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*
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*.** .
** ......
**0* *
5.
Type section of the Carys Mills Formation
6.
Insoluble residue content of limestones
41
Mills
Formation
43
.......................
Insoluble residue variation in the upper
limestone member of the Carys Mills Formation.
9.
...............
*.....
....
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....
...
63
bed
............................
64
Intraformational structures in a limestone
conglomerate
14.
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Imbrication at the base of a limestone
conglomerate
13.
50
Sandstone body in a limestone conglomerate
bed
12.
45
Distribution of benthonic fauna of the
Carys Mills Formation
11.
44
Insoluble residue variation in the lower
limestone member of the Carys Mills Formation.
10.
22
Grouping of insoluble residue data of the
Carys
8.
19
33
of the Carys Mills Formation .................
7.
14
bed
............................
65
Erosional contact at the base of a limestone
conglomerate bed
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66
Page
Figure 15.
16.
Cross-lamination -in a graded
sandstone
17.
bed
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74
,...................
bed
75
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Groove casts on the base of a graded
sandstone
21.
73
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Flute casts on the base of a graded
sandstone
20.
bed
Large tool marks on the base of a graded
sandstone
19.
71
.........................
bed...
Load casts at the base of a graded
sandstone
18.
bed
.........
,......
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80
84
Paleocurrent directions from sandstones of
the Siegas Formation at EM558 ...........
25.
77
Variation of sandstone compositions of
the Siegas Formation at EM558
24.
75
Vertical lithologic variations of the
Siegas Formation at EM558..........
23.
.
Parting lamination in the interior of a
graded sandstone bed
22.
70
A graded bed of the sandstone lithotype
86
Schematic cross-section of the Siegas
Formation .... ..............................
89
26.
Facies of the Siegas Formation
91
27.
Variation of total quartz in sandstones
of the Siegas Formation ....................
28.
93
Variation of plagioclase feldspar content
in the Siegas Formation ....................
94
10
Page
Figure 29.
Variation of total potassium
feldspar in the Siegas Formation
30.
95
Variation of total salic plutonic content
in the Siegas Formation
31.
96
Variation of mafic volcanics in sandstones
of the Siegas Formation ......................
32.
Variation of limestone content of sandstones
of the Siegas Formation
33.
...................
*
Formation
... .0....................
0
Siegas
Formation
........................
106
Formation
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111
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Structural cross-section at the TH165
section
39.
119
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Structural cross-section at the DR1065
section
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40.
Structural map of EM557
41.
Distribution of bedding poles of the thesis
......................
area domain ..............
42.
105
Sedimentary transport and environment of the
Siegas
38.
103
'Matrixvariation in sandstones of the
Siegas Formation
37.
100
Grain size distributions of sandstones of
the
36.
99
Roundness of quartz of sandstones of the
Siegas
35.
...................
Variation of pyroxene content of sandstones
of the Siegas Formation
34.
98
. .
. . .
. .
. ..
120
122
125
Distribution of bedding poles of the
Silurian domain
.............................
*
126
Page
Figure 43.
Distribution of bedding poles of
the Ordovician domain
44.
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...
Distribution of bedding poles of
129
the Carys Mills domain ......................
45.
Distribution of bedding poles of the
130
Madawaska Lake domain......
46.
Distribution of cleavage poles of the
132
Lower Perham donain..................
47,
Distribution of cleavage poles of the
133
Madawaska Lake domain .......................
48.
Outcrops and structural data of the
inside
back cover
Siegas area, New Brunswick ..................
49.
127
Geological map of the Siegas area,
New
Brunswick
...........
,.......
......
.
inside
back cover
INTRODUCTION
ACKNOWLEDGEMENTS
This thesis was written under the supervision of
Dr. E. Mencher of the City College of New York and Dr.
R.R. Schrock of the Massachusetts Institute of Technology.
The author is grateful to T.B. Griswold of Kentucky State
University and to G. Planansky of Harvard University for
their assistance during the field season of 1967.
T.B. Griswold was responsible for the photography
accompanying this thesis.
The author is particularly
indebted to Dr. A.J. Boucot of the University of
Pennsylvania, Dr. W.B.N.
Berry of the University of
California, Dr. J.M. Berdan and Dr. R.B. Neuman of the U.S.
Geological Survey for the paleontological information
that is essential to this thesis.
Dr. R.S. Naylor of the
Massachusetts Institute of Technology kindly read portions
of the manuscript.
Acknowledgement is given to the
Atlas Construction Company of Fredericton, New Brunswick,
who allowed the author access to their quarry workings in
the thesis area.
Field and laboratory work resulting in this
thesis was financially supported by the National Science
Foundation (Grant GP-1547 to E. Mencher).
Special thanks are due to the writer's wife, Carol, for
her continual encouragement and assistance and for the typing
of this thesis.
PREVIOUS WORK
An index map showing the location of the thesis area
and the geographical names referred to in the thesis is
presented in Figure 1 (p. 14).
The first geologist to visit the Siegas area was Dr. C.J.
Jackson.
Despite his concluding comment, "The geology of
Madawaska is simple and not very interesting," (Jackson, 1837,
p. 73) investigation of the area continued.
Information of
direct use to this thesis was first obtained by the
stratigraphic work of O.OL Nylander (1940).
W.J. Wright (1945)
area.
A few years later,
studied some of the limestones of the thesis
More recently, reconnaissance mapping has been carried
out on the area by E. Mencher and D.C. Roy (1963-66, unpublished
work).
This work established general features of the
stratigraphy in the thesis area.
PRESENT WORK
The outcrops and structural data of the thesis area are
summarized in Figure 48.
is presented in Figure 49.
A geological map of the thesis area
Particular outcrops in the thesis
area are denoted by two letters followed by a one to four digit
number (i.e.,
R4558).
The purpose of this thesis is to define the detailed
sedimentary and tectonic environment of a small area during the
Taconic orogeny.
The Siegas area was chosen to include the
14
FIGURE
INDEX MAP OF
THE S/IEGAS AREA,
NEW BRUNSWICK
NEW ENGL AND AND THE
MARITIME PROVINCES
NORTHERN MAINE
AND
VIC INITY
nee mks
to
so
so
SGO
egik
Cap
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.;Arc
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D~-.~e
C
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3i-z,
,*~
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Ccu
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herngu sota~
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acu"
a
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-
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-C-014r
I,
Pa-en
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cjt cpCori
C,7e
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LI4'Mnce
Sant LaIr
PRINCE
EDWARD-
r.1otteto[n
15
well-exposed succession of Early Llandovery sandstones at E558,
The nature of the thesis study required refinement of the
previously established stratigraphy and detailed mapping
within the thesis area.
However, most of the thesis is devoted
to detailed study of the Carys Mills Formation of Late
Ordovician age and the Siegas Formation of Early Llandovery age.
Field work in the summer of 1967 was divided equally
between study of the exposure at EM558 and study of the
outcrops of the rest of the thesis area.
With the exception of
EM558 the outcrops of the thesis area are small and poorly
exposed.
Stratigraphic correlation was limited to the scale of
individual formations.
Structural analysis was limited by the
general lack of information concerning mesoscopic structural
features.
Laboratory studies in 1967 and 1968 included
petrographic work on sandstones of the thesis area, insoluble
residue analysis of limestones, and stereographic structural
analysis of folding.
REGIONAL SETTING
A map showing major structural features of northern M1aine
is presented in Figure 2 (p. 16).
Most of northeastern Maine and northwestern New Brunswick
is underlain by Ordovician, Silurian, and Devonian rocks of the
eugeosynclinal suite of the Appalachian geosyncline.
These
rocks are tightly folded and locally faulted as a result of
deformation in the Taconic and Acadian orogenies.
The Taconic
FIGURE 2 ' SOME TECTONIC
FEATURES OF NORTHEASTERN
MAINE AND VICINITY
S TOCKHOL M
MOUNTAIN
(NCLINORIUM
NEW
pt~st' Rack
BRUNSWICK
CHAPMAN SYNCLINE
.w..+oik
.Fredericton
WEEKSBOO -LUNKSOOS
ANTI CL I NORIUM
0
1*
zo
.0
#6
50
- PORTAGE ANTICLINE
dffer PAVL IDES and others (1964)
and HALL (1964)
orogeny took place from the middle Ordovician to the early
Silurian and affected the entire region with the exception of
the Aroostook-Mvatapedia belt (Pavlides and others, 1968).
The
Acadian orogeny, which took place from the early to the late
Devonian, affected the entire region and produced the present
sub-chlorite grade of regional metamorphism.
The thesis area is located on the western flank of the
Stockholm Mountain synclinorium within the region of
transition from the Taconic folded belt of the west to the
Aroostook-Matapedia belt in the east.
However, most of the
structural features of the thesis area were produced by the
Acadian orogeny.
The thesis area is underlain by folded and
faulted Ordovician and Silurian sedimentary rocks.
The rocks
are considered to be unmetamorphosed and are referred to by
the nomenclature of sedimentary rocks.
Rocks referred to as
"slate" are argillaceous rocks essentially characterized by the
presence of cleavage.
term.
No metamorphic grade is implied by the
18
LOCAL STRATIGRAPHY
SUM4ARY
The generalized stratigraphy of the thesis area is
summarized in Figure 3 (p. 19).
The stratigraphic succession
in the thesis area is grossly similar to that described by
Boucot and others (1964) for the Presque Isle quadrangle,
as modified by subsequent work of Mencher and others (196367, unpublished reconnaissance).
The oldest unit exposed in the thesis area is the
Madawaska Lake Formation of late Middle Ordovician age.
The formation is at least 1950 feet thick in the thesis area
and is composed of dark gray slate with minor shale and
quartzose sandstone.
The base of this formation is not
seen in the thesis area.
The Carys Mills Formation of Upper Ordovician.to
lowermost Silurian age conformably overlies the Madawaska
Lake Formation in the thesis area.
The Carys Mills Formation
is about 1300 feet thick and is characterized by monotonous
sequences of interbedded state, shale, and limestone.
Variation of the abundance of limestone within the formation
has been used as the basis for a division of the Carys Mills
Formation in the thesis area into three members which are
in vertical succession.
The Siegas Formation of Early Llandovery age overlies
the Carys Mills Formation with general conformity within the
FIGURE 3 GENERAL IZED
STRATIGRA PHY( OF THE
THESIS AREA
EUROPEA N
STANDARD
SEC TION ,
THESIS
Ttt
I
PERHAM
31 FORMATION
30
29
8
27
4
X.
Lowe r
Member
26
4
C6 25
24
FOSSIL AGES
-r
,-
clcarecous
Member
o
T
| NAM ES rLITHOLOGIES
Upper
(J
AREA
shdle and
silfsf one,
minor
sa ndstone
ca/careous
slate end
minor
siltsftone
23
C3
C2 22
21
C,
U
)
0
O
widdlec
to
-4
20
'9
A 18 SIEGAS
17 FORMATION
16
CARYS MILLS
11
FORMATION
MADAWASKA
LAKE
FORMATION
'
UPPER
Ashqill
010
Lu
Q/2
_
_
G
T
/1mestone
limestone
cnd slee
,
slate ond
minor shdle,
sendstone
1/0
_io
1-1
sdendsftone
s/esf nd
_
I_,
-9rapfollfe zones
- thickness in fee t
*
- sfreigraphic level of fossils
range of dge
-biosfrfigrdphic
EUROPEAN STANDARD SECTION end grdpfolife zones -dken from
PAVLIDES
Dnd BERRY (1966)
cind
PAVLIDES dnd others (1964)
20
thesis area.
Local unconformity due to submarine erosion is
observed at DR1066.
The thickness of the Siegas Formation
The
varies from 790 to 350 feet within the thesis area.
formation is composed of sandstone and slate with minor
conglomerate, shale and limestone.
Regional considerations
suggest that the Siegas Formation is of local extent,
disappearing abruptly to the south and east of the thesis area.
The lower member of the Perham Formation conformably
overlies the Siegas Formation in the thesis area.
The age
of the lower member is poorly established in northern Maine
as possibly Middle Llandovery through Wenlock.
The lower
member in the thesis area is composed of gray, calcareous
slate with minor siltstone and is about 600 feet thick.
The upper member of the Perham Formation conformably
overlies the lower member in the thesis area.
member is
The upper
Early Ludlow in age and is composed of calcareous
shale and siltstone with minor slate, limestone and
sandstone.
The thickness of the upper member was not
determined in the thesis area, but is-probably in excess of
2000 feet.
The upper member of the Ferham Formation is
the
youngest stratigraphic unit observed in the thesis area.
Significant lateral facies changes within the thesis
area are known to exist in the Madawaska Lake,Carys Mills
and Siegas Formations.
21
MADAWASKA LAKE FORMATION
Distribution and Thickness
The Madawaska Lake Formation is an informal name
applied by Mencher and others (i.e. Laux and Warner, 1966,
p. 9) to a distinctive slate unit exposed in the core of the
Pennington anticlinorium north of the Portage anticline.
The
base of the Madawaska Lake Formation is not seen throughout
its area of outcrop.
In the thesis area the minimum thickness
of the formation is about 1950 feet.
Lithology
The abundance and vertical distribution of the lithotypes
of the Madawaska Lake Formation are sumnmarized in a generalized
section in Figure 4 (p. 22).
This section is based on exposures
between Upper Siegas and the Grand River (Figure 48).
Work
in the rest of the thesis area suggests the possibility of
significant lateral facies changes within the formation.
The
exact nature of these facies changes has not been determined
but it is clear that the distribution of lithotypes as shown
in Figure 4 is only of local significance.
The most abundant and characteristic lithotype of the
Madawaska Lake Formation is dark gray, noncalcareous, laminated
slate.
The laminae are indistinct zones of very dark gray
slate from k to 1 inch thick.
The slate weathers medium
22
GENERALIZED
FIGURE 4
SECTION OF THE MADAWASKA
LAKE
FORMA TION
pdrf of sec-hon
exposcd in oufcrop
/00
~sa
200
nds-fonc
shdlc
C~ ~
slafe
TH359
400
TH358
600-J
TH204
TH205
TH2OI
CTH08
CTH198
TH 99
0
ZC
/300
-
c TH197
cTH2/0
Lu
cTH196
??
'7tX
,am.
)10
lI
2
3
I
I
I
20 30 405060 70
PERCENT ABUNDANCE OF SANDSTONE
Tus
23
greenish gray and the laminae weather dark greenish gray,
The laminae are irregularly spaced in the slate at intervals
from 2 to 10 inches.
The thickness of individual slate beds
is difficult to determine.
The slate is overwhelmingly
abundant in the upper part of the formation throughout the
thesis area.
The most distinctive minor lithotype of the Madawaska
Lake Formation is light gray, highly calcareous, quartzose,
fine-grained sandstone.
This sandstone occurs in beds from
1 inch to 4 feet thick which are usually laminated and often
cross-laminated.
Laminae are k- to 1/16-inch segregations
of very highly calcareous, medium-grained sandstone containing
micaceous minerals.
Examination of thin sections of the
sandstone shows the composition to be very uniform within the
thesis area.
The approximate modal composition of the
sandstone lithotype is summarized below.
quartz
70%
calcite
25%
plagioclase
3%
biotite
1%
lithic fragments
traces
sphene
traces
The quartz grains are well sorted but quite angular and appear
in thin section to be "floating" in a matrix of coarsely
crystalline calcite.
The sandstone occurs from top to bottom
of the Madawaska Lake Formation but thickly bedded sequences
24
where sandstone is abundant are restricted to the lower part
of the formation.
Sandstones also appear to be more abundant
in the Madawaska Lake Formation in the northeast part of the
thesis area.
The other minor lithotype of the formation is
noncalcareous, gray, laminated, micaceous, coarse-grained
siltstone or shale.
The laminae are 1/16-inch segregations
of micaceous minerals and occur regularly at 1/8-inch
intervals within the shale beds.
fissile and occurs in
The shale itself is highly
to 2 inch beds.
A&e
The age of the Madawaska Lake Formation is poorly
established in northeastern Maine as ranging from Zone 12
of the Caradoc to about Zone 15 of the Ashgill.
(Laux and
Warner, 1966, p. 11; Mencher and others, unpublished
information).
In the thesis area, graptolites collected at
TH205 about 800 feet below the top of the formation were
considered to be of Zone 13 age by R.B. Neuman (oral
communication, 1967) on the basis of a field identification.
A minimum age of earliest Late Ordovician can be assigned
to the top of the Madawaska Lake Formation in the thesis
area on the basis of the age of the Carys Mills Formation
(p. 37).
25
PERHAM FORMATION
The Perham Formation was originally defined and divided
into an upper and lower member by Boucot and others (1964)
in the Presque Isle quadrangle.
The formation has been
extended as far as northwestern New Brunswick by unpublished
mapping of E. Mencher, D.C. Roy and others (i.e. Laux and
Warner, 1966, p. 18).
Lower Member
Distribution and Thickness
The lower member of the Perham Formation outcrops on the
east limb of the Stockholm Mountain synclinoriutm from Van Buren
south to the Presque Isle region.
The lower member is also
found on the west limb of the Stockholm Mountain synclinorium
northeast of Martin's Siding.
Another area where the lower
member is exposed is in a narrow zone on the west limb of the
Pennington anticlinoriutm extending northeast from Cross Lake
into New Brunswick.
The thickness of the lower member of the Perham Formation
is thought to be about 2000 feet in the Presque Isle area
(Pavlides, 1968, p. 19).
In the thesis area the thickness
of the lower member is well established as 600 feet from
measurements near TH80.
26
Lithology
The lower member of the Perham Formation is composed
almost entirely of gray, calcareous, laminated slate.
laminae are of two types.
The
The first type consists of 1/16-
inch segregations of coarse silt or fine sand grains.
These
laminae are generally light gray, highly calcareous and may
be internally laminated and cross-laminated.
type of lamination consists of k- to
segregations of dark gray slate.
The second
-inch indistinct
Both types of lamination
occur irregularly in the slate at intervals of
to 3 inches.
The thickness of individual slate beds is difficult to
determine.
The minor lithotypes of the lower member make up a
distinctive assemblage consisting of red and green slates
and ferrous, siliceous siltstone.
In the thesis area these
rocks are restricted to a stratigraphic interval of 50 feet
or less in thickness occurring about 200 feet above the base
of the member.
These rocks are equivalent to the "manganese
deposits" mentioned by Boucot and others (1964, p. 35) and to
similar sequences in northeastern Aroostook County.
In the
thesis area the red and green slates are generally similar
to the normal gray slate of the
lower member with the
exception of color.
The color of the "red" slate is actually
dark reddish brown.
A continuous series of lithologic
variations exists between these red and green slates and the
ferrous siliceous siltstone.
The latter lithotype is
27
composed of k- to
-inch layers of dark red siliceous
siltstone and medium green siliceous siltstone.
are generally highly calcareous.
The layers
The siliceous siltstone
occurs in poorly defined beds from four to ten inches thick
associated with poorly defined beds of red or green slate.
Age
In the Presque Isle area the age of the lower member of
the Perham Formation has been poorly established as postEarly Llandovery pre-Ludlow (Pavlides, 1968, p. 19).
No
fossils have been found in the lower member in the thesis area.
The age is between that of the Siegas Formation (p. 61)
and the upper member of the Perham Formation and is in
agreement with that determined in the Presque Isle area.
Contact with the Siegas Formation
In the thesis area the lower member of the Perham
Formation overlies the Siegas Formation with conformity.
The contact is exposed at &1558 and TH181.
The top of the
Siegas Formation is defined as the top of the uppermost
sandstone bed in the transitional interval between the two
formations.
At the two exposures there is an abrupt but
conformable transition from the sandstones and slates of the
Siegas Formation to the slate of the lower member of the
Perham Formation.
Due to the nature of facies changes in the
28
Siegas Formation some ambiguity exists as to the definition of
this contact in the northeastern part of the thesis area.
This problem will be discussed later in the thesis (p. 88).
Slump Structures
The beds of the lower member of the Perham Formation at
EM558 show features of large scale soft-sediment deformation.
Bedding in the slates immediately overlying the Siegas
Formation is irregularly contorted with local disruption by
small faults and clastic dykes.
throughout the exposed rock.
These structures extend
The size of the exposure
corresponds to a body of deformed sediment with a minimum
volume of about 8 X 104 cubic feet.
Deformation evidently
took place by slumping of a large mass of hydroplastic sediment.
This slumping, however, resulted in internal readjustments
only on the order of a few inches and the mass as a whole
remained coherent.
According to Moore (1961) slumping of fine grained
sediments is due either to very rapid deposition or to
deposition on very steep slopes.
As slumping is only a local
feature of the lower member, the conditions producing slumping
at 3-4558 should only have local significance.
The lithologic
uniformity of the Perham Formation over its entire area of
outcrop suggests that sedimentation rates throughout the
formation were relatively uniform.
The original slumping was
probably produced by deposition on steep slopes in the
29
neighborhood of
M4558.
This aspect of pre-lower member
topography is closely related to the sedimentation of the
Siegas Formation (p. 113).
Upper Member
The upper member of the Perham Formation was not
specifically studied in this thesis and will not be discussed
in detail.
Observations in the thesis area were generally
consistent with those of the Presque Isle region (Boucot and
others, 1964, p. 34) and the Stockholm area (Laux and Warner,
1966, p. 21).
In the thesis area the upper member consists of
a distinctive assemblage of shale and siltstone lithotypes with
minor sandstone beds.
The fine-grained calcareous sandstone
beds are generally graded and often are laminated and crosslaminated.
The age of the upper member ranges from late
Wenlock through the Early Ludlow (Pavlides, 1968, p. 21)
but in the St. John River valley area only Early Ludlow ages
have been reported (Mencher and others, unpublished information).
The upper member of the Perham Formation overlies the lower
member with apparent conformity.
The contact is not exposed
in the thesis area and it is assumed that the relationship is
the same as that in the Presque Isle region (Boucot and others,
1964, p. 34).
The thickness of the upper member was not
determined in the thesis area but is probably in excess of
2000 feet.
The upper member of the Perham Formation is the
youngest stratigraphic unit in the thesis area.
30
CARYS MILLS FORMATION
SUMMARY
The Carys Mills Formation outcrops in the core of the
Aroostook-Matapedia anticlinorium from the Houlton area
northeast into New Brunswick.
It also outcrops on both
flanks of the Pennington anticlinorium in the St. John River
area.
In the Aroostook-Matapedia anticlinorium the thickness
of the Carys Mills Formation is 9000 to 12000 feet.
In the
thesis area the formation is only 1300 feet thick.
In the thesis area the Carys Mills Formation has been
divided into three members in vertical succession.
The lower
limestone member is composed of interbedded limestone, slate,
and shale and is 700 feet thick.
The middle slate member is
composed mainly of slate with minor sandstone and shale and
is 350 feet thick.
The upper limestone member is composed of
interbedded limestone, slate, and shale and is 300 feet thick.
In the thesis area the Carys Mills Formation overlies
the Madawaska Lake Formation with conformity.
In the Aroostook-Matapedia anticlinorium the age range
of the Carys Mills Formation includes Zone 13 of the Caradoc
through Zone 19 of the Llandovery.
In the thesis area the
age range is significantly smaller including at the most
latest Middle Ordovician through earliest Silurian.
Significant facies changes take place in the Carys Mills
Formation within the thesis area.
Lithologic variations
within the limestone 'members of the formation show increasingly
unsuitable conditions for carbonate sedimentation towards the
north part of the thesis area.
Insoluble residue analysis of
limestone samples shows the increasing relative importance of
terriginous sedimentation towards the north which suggests
the presence of a source of terriginous clastic sediment to the
north of the thesis area.
The depositional environment of the Carys Mills Formation
suggested in this thesis is based mainly on the nature of
sedimentation of the characteristic limestone lithotype of the
formation.
Sedimentary structures of the limestones show that
turbidite sedimentation was insignificant in the thesis area
although resedimentation of carbonate material by normal
bottom currents was a minor factor.
The distribution of
benthonic faunal remains of the limestones suggests that the
environment was fundamentally related to biological processes.
A model of carbonate sedimentation applicable to the Carys
Mills Formation is presented, whose modern analogue is carbonate
deposition in the deep Black Sea.
This process is essentially
the accumulation of biogenic carbonate detritus beneath
stagnant bottom waters.
The environment in the thesis area
was one of transition from anerobic bottom waters in the south
part of the thesis area to more aerated bottom waters in the
north.
This transition suggests a shallowing of the
depositional surface towards the north, in the direction of the
source of terriginous sediment.
The increasingly inappropriate
conditions for carbonate deposition towards the north was
32
probably related to variations in the microbiotic productivity
of surface waters.
The Carys Mills Formation in the thesis area is a
marginal facies of the formation as a whole.
Application of
the Black Sea model to regional aspects of the Carys Mills
Formation is discussed later in the thesis (p.14 2 ).
DISTRIBUTION AND THICKNESS
The Carys Mills Formation outcrops in the core of the
Aroostook-Matapedia anticlinorium from the Houlton area to
northern New Brunswick (Pavlides, 1968, p. 2).
The formation
also occurs on the flanks of thePennington anticlinorium in
the St. John River area (Mencher and others, unpublished
reconnaissance).
The thickness of the formation ranges from
12000 to 1500 feet in the Bridgewater quadrangle and is 9000
feet in the Presque Isle region (Pavlides, 1968, p. 10).
In
the thesis area the Carys Mills Formation is 1300 feet thick.
DETAILED STRATIGRAPHY
In the thesis area the Carys Mills Formation has been
informally subdivided into three members in vertical sequence.
The type section for the division extends from DR1066 to TH50
including many nearby outcrops.
Figure 5 (p. 33) contains a
generalized lithologic column for this section.
The details
of this figure are applicable only to the type section.
TYPE SECTION
5
OF THE CARYS MILLS
FIGURE
FORMATION
__
PERCENT ABUNDANCE
OF LIMESTONE
Member
Lifhologic Oufcrop
Divisions
Con-frol O /0 ;O
Column
O 04,050 6p 70 8,90
EM323
DR1066
I
.
i
I
/00
.
.
.
Lifesfone
LTH23
Member
i:TH22
200
cTH24-25
300
[TH217
H 3-14
4q0-
Middle
Sldfe
Member
-TH223
(TH216
600700.
u-
-
-
l
-
TH2,,
14
ET H2
800
Lower
9001
Limesf one
Member
0 1000
(i:
DR 1065
HOO0
1202
~TH241-2
1300
c TH25 0
limesfone
Rr+of scCf on
exposed in oufcrop
E3 Sdndsfone
shle
~~
SldfC
TH5
34
Lower Limestone Member
The lower limestone member of the Carys Mills Formation
conformably overlies the Madawaska Lake Formation and
conformably underlies the middle slate member of the Carys
Mills Formation.
The former relationship will be discussed
later in the thesis (p. 36).
The type locality of the lower
member is DR1065 where the thickness is 690 t 150 feet.
The
thickness at TH49 is 750 t 150 feet and is 650 t 100 feet at
TH360.
The thickness of the lower limestone member is
constant within the thesis area at 700 feet.
The member
consists of interbedded limestone, shale, and slate.
abundances of these lithotypes are given in Figure 5.
characteristic lithotype is
The
The
dark gray, fine-grained limestone
which is typically hard, compact and brittle.
limestone is
probably
The weathered
either light bluish gray or light brown and occurs
in well-defined beds from k to 16 inches thick.
The beds have
either no internal structures or abundant lamination and crosslamination.
These two varieties are,- respectively, the
"limestone almost free of quartz" and the "quartzose limestone"
of Pavlides (1965, p. 17, p. 15).
The laminae are 1/32-inch
segregations of silt-sized quartz grains and occur at
irregular intervals throughout the bed.
The troughlike cross-
laminated units are as thick as 10 inches.
Graded bedding
occurs locally in thin beds with abundant silt-sized quartz,
associated with load casts.
The limestone lithotype is
discussed in more detail below (p. 46).
The slate of the'member is dark gray, micaceous, and
laminated.
variable.
Other characteristics of the lithotype are
The shale of the member is dark gray, slightly
calcareous and laminated.
The laminae are 1/16- to
-inch
segregations of highly calcareous, coarse-grained siltstone
and are often internally structured by cross-lamination and
load casts.
The shale occurs in poorly defined beds from
2 to 8 inches thick.
Middle Slate Member
The middle slate member of the Carys Mills Formation
conformably overlies the lower limestone member and conformably
underlies the upper limestone member.
TH216 and TH217 together
make up the type locality of the member.
middle slate member there is
The thickness of the
350 1 50 feet.
The member consists mainly of slate, with minor shale and
sandstone.
Figure 5.
The abundances of the lithotypes are given in
The shale is identical to that of the lower
limestone member.
The slate is similar to that of the lower
limestone member but is noncalcareous.
The sandstones of the middle slate member are of two types.
The common type is light gray, fine-grained, highly calcareous
sandstone that is usually laminated and cross-laminated and
occurs in 2- to 8-inch beds.
weathered and medium brown.
The beds are usually deeply
The second type of sandstone is
dark gray, medium grained, slightly calcareous and occurs in
36
2- to 4-foot beds.
The beds are graded in the lower parts and
laminated or cross-laminated in the upper parts.
The sandstone
is lithic, feldspathic and quartzose and is similar to the
lithic wackes of the Siegas Formation (p.
68).
Upper Limestone Member
The upper limestone member of the Carys Mills Formation
conformably overlies the middle slate member and conformably
underlies the Siegas Formation.
discussed later in the thesis (p.
The latter relationship is
59).
The type locality is
DR1066 where the thickness is 250 ± 50 feet.
There the
member is overlain by the Siegas Formation with unconformity
due to submarine erosion (p. 61).
Comparison of the type
section to conformable sections in the thesis area indicates
that about 30 feet of slate have been removed at DR1066.
The
thickness of the upper limestone member was 300 feet before
erosion.
The member consists of interbedded limestone, shale, and
slate.
5.
The abundances of the lithotypes are given in Figure
The lithotypes are identical to those of the lower
limestone member.
RELATIONSHIP TO THE MADAWASKA LAKE FORMATION
In the thesis area the Carys Mills Formation conformably
overlies the Madawaska Lake Formation.
The base of the Carys
Mills Formation is
defined as the base of the lowermost bed of
the characteristic limestone lithotype.
The contact is not
completely exposed in the thesis area but intermittent
exposure crosses the contact at DR708-709 and TH360-361.
There
the abundance of limestone decreases continuously from 40% at
the top of the section to zero at the base, where dark gray
slate of the Madawaska Lake Formation is dominant.
This
gradual change takes place over a stratigraphic interval of
about 100 feet.
Regional relationships of the Carys Mills Formation to the
Madawaska Lake Formation will be discussed later in the
thesis (p.140 ).
AGE
In the Aroostook-Matapedia anticlinorium the age of the
Carys Mills Formation ranges from Zone 13 of the Caradoc to
Zone 19 of the Llandovery (Pavlides, 1968, p. 11).
In the thesis
area the age range is smaller including at the most latest
Middle Ordovician through earliest Silurian.
Relevant
paleontological information is summarized in Appendix 1
(p. 148 ).
A late Middle to Late Ordovician age has been found for
graptolites from E-1326 (Mencher and others, unpublished
information).
The beds at EM326 are of the lower limestone
member and occur about 1000 feet higher in the section than
beds of the Madawaska Lake Formation of Zone 13 age (p. 24).
38
Accordingly, a Late Ordovician age is probable for D1326.
Collections from EM661 include ostracodes and graptolites.
The graptolites are either Late Ordovician or early Silurian
and are more suggestive of an early Silurian age (Berry,
written communication).
1968,
The ostradodes are either Ordovician
or Silurian and are more suggestive of an Ordovician age
(Berdan, 1968, written communication).
The beds at EM661 are
of the upper limestone member and occur about 1000 feet lower
in the section than beds of the Siegas Formation of Early
Llandovery age (p.
61).
earliest Silurian age is
Accordingly,
a Late Ordovician or
probable for E661.
Detailed stratigraphic and faunal correlations (p. 150).
show that TH165, TH308 and E1154 represent the same beds.
With the exception of Berounella (p.
153), ostracodes collected
from these outcrops indicate an age between Late Ordovician
and Early Devonian (Berdan, 1968, written communication).
Since the beds are of the upper limestone member a Late
Ordovician or early Silurian age is most probable.
FACIES VARIATIONS
Stratigraphic Variations
Lower Limestone Member
Partial sections through the lower limestone member
include EM326, DR708, TH50, TH360 and DR1065.
With this type
39
of exposure general trends across the thesis area can be
recognized.
The abundance of the limestone lithotype
decreases from the southwest to the northeast.
The thickness
of the lower limestone member is essentially constant.
No intermediate forms between the limestone lithotype
and calcareous siltstone occur in the Carys Mills Formation.
The decreasing abundance of limestone towards the northeast
must be the result of relatively abrupt disappearance of
individual limestone beds.
Sedimentary conditions were
generally less suitable for carbonate sedimentation in the
northeast than in the southwest part of the thesis area.
Upper Limestone Member
Partial sections through the upper limestone member
include E322, E-661,
TH124,
EM1154 and DR1066.
Both the
abundance of the limestone lithotype and the average thickness
of the limestone beds decrease towards the northwest part of
the thesis area.
The decrease in abundance is probably
produced by the thinning of individual limestone beds.
Evidently suitable conditions for carbonate sedimentation
existed throughout the thesis area with a decreasing rate of
carbonate deposition towards the northeast.
Variations in the thickness of the upper limestone
member are due to submarine erosion and are discussed later
in the thesis (p.
60).
40
Insoluble Residue Analysis
Method of Analysis
The method of analysis is fully discussed in Appendix 2
(p. 159).
The solubility in 4N HUI was found for a number of
samples of the limestone lithotype.
The insoluble residue
values are summarized in Figure 6 (p. 41).
These values are
not the concentrations of noncarbonate minerals.
However,
relative values probably represent variations in the abundance
of noncarbonate minerals in the samples.
The variation of insoluble residue content of the samples
is the product of two processes.
The first is the vertical
variation of insoluble residue content at a particular place
through time.
The second is the spatial variation of
insoluble residue content at a particular time in the thesis
area.
The nature of vertical variations in three sections
through the upper limestone member is summarized in Appendix 3
(p. 163).
The average standard deviation of insoluble residue
content for these sections is 4.9 percent.
If it is assumed
that this value can be applied to both the upper and lower
limestone members throughout the thesis area then any set of
raw data with a standard deviation greater than 4.9 percent
represents the combined effects of vertical and lateral variation.
The standard deviation for the upper limestone member is 6.8
percent for the lower limestone member is 5.8 percent.
The
FIGURE 6 INSOLUBLE RESIDUE
CONTENT OF LIMESTONES OF
THE CARYS MILLS FORMATION
NUMBER OF
LOCALITY
SAMPLES
PERCENT
MEMBER
INSOLUBLE RESIDUE
TH1
upper
TH18
lower
11.4
TH50
lower
11.9
TH51
lower
15.0
TH165
upper
19.0
TH1 71
lower
23.6
TH260
lower
6.9
TH261
lower
6.0
TH264
lower
10.8
TH308
upper
25.7
TH360
lower
23.5
TH386
lower
21.7
TH408
lower
TH413
upper
8.6
EAM326
lower
15.8
EM661
upper
18.2
EM1154
upper
22.8
EM1184
lower
16.5
DR699
lower
14.4
DR700
lower
14.9
DR1065
lower
7.5
23.3
23.4
23.4
20.0
42
lateral variation of insoluble residue content is probably of
the same order of magnitude as the vertical variation.
The lateral variation is of particular interest.
It is
most practical to arrive at the nature of the average lateral
variation over a time span equivalent to the thickness of a
member of the for-nation.
Two sets of raw data are available,
one for the upper limestone member and one for the lower
limestone member.
For each set, outcrops which are essentially
in the same vertical section have been grouped as shown in
Figure 7 (p. 43).
The individual insoluble residue values
are averaged over the group, thus reducing the effect of
vertical variations in the resultant percentages.
Contouring
the grouped averages at 5.0 percent intervals should provide
a realistic representation of systematic lateral variations.
Lateral Variations of Insoluble Residue Content
The lateral variations of insoluble residue content for
the upper and lower limestone members are presented in
Figure 8 (p. 44) and Figure 9 (p. 45) respectively.
Significant systematic variations appear in both members.
The data of the lower limestone member indicate an increase
in soluble residue content towards the northwest part of the
thesis area.
The data of the upper limestone member indicate
a systematic variation that is consistent with that shown
for the lower limestone member.
These variations are not the same as the original
43
FIGURE 7 GROUPING OF
INSOLUBLE RESIDUE DATA OF
THE CA RYS MILLS FORMATION
GROUP
UPPER
MEMBER
LOCALITIES
WITHIN GROUP
AVERAGE %
INSOLUBLE
R ES IDUE
A
Em1154
22.8
B
TH165, TH308
22..4
C
TH1I,
D
TH413
E661
12.9
8.6
LOWER
MEMBER
E
TH408
23.3
F
TH386
21.7
G
EM1184
16.5
H
TH360
23.5
I
TH171
23.6
J
TH260, TH261, TH264
K
TH18
11.4
L
DR1065
21.7
M
TH50, DR699, DR700
13.7
N
TH51, EM326
15.4
7.9
44
FIGURE 8
INSOLUBLE RESIDUE
VARIATION IN THE UPPER L IMES TONE
MEMBER OF THE CARYS MILLS
B -GROUP DESIGNATION
AS IN FIGURE 7
o - GROUP LOCATION
12.9-AVERAGE %
INSOLUBLE RESIDUE
AS IN FIGURE 7
~N
~, ~\
no
0
~fm
aem
m
o
mm0
o
io
am
xw
2=
KM
4ow'-,
%
45
FIGURE 9 INSOLUBLE RESIDUE
VARIATION IN THE LOWER LIMESTONE
MEMBER OF THE CARYS MILLS
E-GROUP DESIGNATION
AS IN FIGURE 7
e - GROUP LOCATION
12.9 -AVERAGE
%
INSOLUBLE RESIDUE
AS IN FIGURE 7
e
N
,,
~
46
variations on the depositional surface as a result of the
deformation of the depositional surface during folding of
the thesis area.
It is not possible to construct palinspastic
maps of the thesis area (p. 135).
Since the depositional
surface has been compressed in a NW-SE direction the
original direction of increasing insoluble residue content
would have been more towards the north.
The increasing insoluble residue content in samples of
the limestone lithotype is due to increasing dilution of the
accumulating carbonate by terriginous sediment.
The variations
shown in Figures 8 and 9 indicate a source of terriginous
sediment to the north of the thesis area.
Limestone Lithotype
Mineralogy
Petrographic characteristics of the limestone lithotype
of the Carys Mills Formation have been summarized by Pavlides
(1965, p. 17-18).
The results of examination of thin sections
from the thesis area are identical to the findings of Pavlides.
The uniformity of the grain size of the carbonate material is
probably the result of homogeneous recrystallization.
The
limestone lithotype in the thesis area may have a high content
of organic carbon.
Abundant organic material was released
from samples by acid digestion during insoluble residue
analysis.
Sedimentary Structures
Sedimentary structures of the limestone lithotype
within the thesis area include lamination, cross-lamination,
convolute lamination, graded bedding and load casts.
These
structures were studied both in the field and by microscopic
examination of etched surfaces of samples.
In the thesis area about 80 percent of all limestone beds
had no sedimentary structures, about 15 percent had crosslamination or convolute lamination and about 5 percent were
simply laminated.
Only three graded beds were observed in
the thesis area.
Laminae of the limestones are of two types.
The common
type consists of 0.01-inch thick segregations of silt-sized,
angular quartz grains.
These laminae are spaced throughout
the bed at 0.04- to 0.5-inch intervals.
The second type
consists of 0.02-inch thick segregations of 0.004- to 0.01inch bioclastic carbonate grains.
Cross-lamination, often modified-by convolute lamination,
occurs in units from 0.1 to 10 inches thick.
The form of the
corss-laminated units is troughlike or irregular.
Quartz
grains are abundant in cross-laminated beds and fossils are
absent.
At EM326 a graded bed 0.4 inch thick contained a high
concentration of quartz grains ranging in size from 0.002 inch
at the top of the bed to 0.01-inch at the base.
Near the base
there were 0.008-inch pelmatazoan fragments and 0.01-inch ostracode
48
shells.
Micro-load casts with a relief of 0.1 inch occurred
at the base of the bed.
Similar graded beds were observed at
EM661 and TH51.
The rare occurrence of graded bedding shows turbidite
deposition to have been insignificant in the sedimentation
of the limestones of the Carys Mills Formation, important
only in the production of transported faunas such as the
assemblage from EM%326.
The relative abundance of cross-
lamination shows resedimentation of carbonate detritus by
normal bottom currents to have been a significant factor in
limestone deposition closely related to the relative
abundance and availability of silt-sized terriginous sediment.
The general scarcity of sedimentary structures implies that
sedimentation of the limestones was not fundamentally related to
near-bottom mechanisms of lateral sediment transportation.
Faunal Distribution
General aspects of the nature and distribution of the
faunal assemblage of limestones of the Carys Mills Formation
were investigated by microscopic examination of insoluble
residues and etched surfaces of samples.
Faunal remains
in the thesis area include pelmatazoan fragments, bryzoans,
ostracodes, brachiopods, sponge spicules, coral fragments,
and graptolites.
This assemblage is dominated by shelly
material, a striking contrast to the generally graptolitic
assemblages of the formation in the Aroostook-Matapedia
49
anticlinorium (Pavlides, 1968, p. 12-13).
Ostracodes range between.0.002 and 0.02 inch in size and
include both smooth and ornamented forms.
are summarized in Appendix 1 (p. 148).
Identified forms
Ostracodes were very
abundant in samples from EM1154, TH308, TH165 and EM661.
Brachiopods were preserved as casts in etched surfaces and
ranged up to 0.04 inch in size.
Sponge spicules were tapering
hollow tubular fragments up to 0.1 inch in length.
tetrahedral spicule fragment was observed.
One
Obscure structures
were observed in etched surfaces of samples from TH165 and
EM1154 that may have been bryzoans in growth positions
(Shorck, 1968, oral communication).
Graptolite fragments
were found in samples from TH260, EM326 and EM661 (p. 148).
The shelly faunal assemblage from E4326 was collected
from the graded bed described in the previous section and is
obviously a transported fauna.
Neither this assemblage nor
the occurrences of graptolites are relevant to the discussion
of benthonic faunal remains.
The size of the shelly fossil remains is generally about
an order of magnitude larger than the size of either the
quartz or the carbonate grains with which the fossils occur.
It is probable that the distribution of shelly faunal remains
in the thesis area reflects in a general way the original
distribution of benthonic organisms.
The distribution of shelly fauna of the Carys Mills
Formation is
expressed in Figure 10 (p.
50).
The average
number of genera for each group is the total number of genera
DISTRIBUTION OF
FIGURE /0
BENTHONIC FAUNA OF
THE CARYS MILLS FORMATION
E-GROUP DESIGNATION
-AS IN F7GURE 7
*
-
GROUP LOCATION
/ -AVERAGE NUMBER
OF GENERA OBSERVED
recognized in all samples from outcrops of the group divided
by the number of outcrops in the group.
Group N was
disregarded in contouring the results since the datum was
based on the faunal assemblage of E4326.
A significant biofacies boundary separates the northern
and southern parts of the thesis area.
The environment of
deposition of the limestones of the Carys Mills Formation
was characterized by a striking change in the thesis area
of the conditions for benthonic life.
LOCAL DEPOSITIONAL ENVIRONMENT
The lithotypes (p. 36) and the sedimentary structures
(p. 48) of the Carys Mills Formation in the thesis area show
that turbidite sedimentation was an insignificant factor in
the deposition of the formation.
The complete absence of
shallow-water sedimentary structures or colonial fauna such
as reefs suggests that the sedimentation of the Carys Mills
Formation was different from modern shallow-water carbonate
deposition.
In such an intractable situation a priori
reasoning is less productive than a modelling approach.
A successful sedimentary model in application to
problems of the Carys Mills Formation both on a local and
a regional scale is based on recent carbonate sedimentation
in the deep basin of the Black Sea.
In the Black Sea,
aerated surface waters overlie completely stagnant bottom
waters (Caspers, 1957, p. 809).
Microbiotic production of
52
calcareous skeletal debris in the aerated life-supporting
surface waters leads to the accumulation of biogenic carbonate
muds on the sea floor (Caspers, 1957, p. 824-825).
These
deposits have no benthonic fauna, abundant pelagic faunal
remains, a high organic carbon content and a low to moderate
content of fine-grained terriginous sediment (Caspers, 1957,
p. 828).
The deposits may be locally reworked by active
bottom currents (Pyrkin and others, 1968).
The skeletal
particles in the calcareous mud break down by the
decomposition of organic binding matter (Matthews, 1966,
p. 452).
The carbonate content of the deposits would vary
with the microbiotic productivity of the surface waters
and the contribution of terriginous sediment.
Application of the Black Sea model to the sedimentary
environment of the Carys Mills Formation in the thesis area
accounts for all the relevant information collected in this
thesis.
The biofacies boundary in the thesis area (p. 50)
marks the separation of stagnant bottom waters in the south
from more aerated bottom waters in the north.
Since dense,
stagnant bottom waters must underlie any lighter, more
aerated waters, the depositional surface in the thesis area
was shallower in the north than in the south.
The local
paleoslope dipped to the south, away from the direction of
the source of the fine-grained terriginous sediment (p. 46).
The local resedimentation of the carbonate detritus by
normal bottom currents (p. 48) and occasional turbidite
deposition (p. 48) suggested for the Carys Mills Formation
53
would be expected in this environment.
Decreasing
sedimentation rates and increasingly unsuitable conditions
for carbonate deposition towards the north part of the thesis
area (p. 39
) are probably related to variations in the
microbiotic productivity of aerated surface waters.
Diagenetic recrystallization of the carbonate muds would
produce the fine-grained, homogeneous texture of the
limestone
lithotype.
This environment of deposition indicates that the
Carys Mills Formation of the thesis area is a marginal
facies of the formation as a whole.
This conclusion is
consistent with current thought as to the regional
sedimentary environment (i.e., Berry, 1968, p. 31).
Applications of the Black Sea model to regional aspects of
the Carys Mills Formation will be discussed later in the
thesis (p. 142).
54
SIEGAS FORM4ATION
SUMMARY
The "Seigas Conglomerate" defined by Nylander (1940)
is redefined as the "Siegas Formation" with the type locality
at E4558.
The formation is of local extent and is absent
8 miles to the southeast of the thesis area.
The thickness
of the formation varies from 790 to 350 feet within the
thesis area.
The Siegas Formation overlies the Carys Mills Formation
with conformity.
Local unconformities at DR1066 and near
Ei558 are due to submarine erosion.
A known maximum of 180
feet of the Carys Mills Formation has been eroded near EM665.
The age of the Siegas Formation is early Llandovery.
A section across the entire formation at E1558 contains
five lithotypes: limestone conglomerate, sandstone, siltstone, limestone, and chert.
The limestone conglomerates
are intraformational and are derived from erosion of semiconsolidated beds of the Siegas and the Carys Mills Formations.
The sandstone lithotype is mainly made up of graded
sandstones produced by turbidite deposition.
Most of the
thicker beds, however, have a base of nongraded coarse
sandstone indicative of extremely proximal conditions.
The normal turbidity currents eroded semi-consolidated
limestone.
The siltstone lithotype consists mainly of slates that
55
are similar to those of the Carys Mills Formation.
The
linestone lithotype is identical to that of the Carys Mills
Formation.
Sedimentation at E558 is divided into in situ
deposition of limestone and slate and exogenic deposition of
sandstone and limestone conglomerate.
The former is a
continuation of the sedimentary environment of the Carys Mills
Formation.
The exogenic deposition took place in three
discrete events, the second of which was a transgressiveregressive sequence of turbidite deposition beginning and
ending with distal conditions and passing through a highly
proximal phase.
Modal analyses of graded sandstones of E558 show that
the nature of the source area remained constant throughout
the early Llandovery.
The more proximal turbidites are less
mature than the more distal phases indicating lateral
segregation in the turbidity flow.
The sandstones are
mainly lithic wackes.
Paleocurrent directions from EA558 are very uniform
and consistently indicate transport from north to south.
The paleoslope at E4558 dipped to the south and was
relatively stable throughout the early Llandovery.
Stratigraphic variations indicate that this paleoslope
extended over the southern and western part of the thesis
area.
The limestone conglomerates are restricted to a
small region near
a558 and abruptly disappear to the south.
Modal analyses of sandstones of the Siegas Formation
56
lead to the definition of three laterally equivalent facies.
The orthoquartzitic facies occurs in the northeastern part
of the thesis area.
The arkosic facies occurs in the south-
central part of the thesis area.
The lithic wacke facies
occurs in the southern and western parts of the thesis area.
Turbidite sedimentation as described at Ev558 took place
only in the lithic wacke facies.
Distributions of the petrographic species show that
the lithic wacke facies accumulated in deeper water than
the arkosic facies.
The sandstones of the lithic wacke
facies are composed of andesitic volcanic fragments and
their disintegration products and were dispersed across
the basin from a restricted source near EB558.
The arkosic
facies accumulated on a slope dipping to the southwest
in shallower water than the lithic wacke facies.
The sand-
stones of the arkosic facies are composed of quartz,
salic plutonic fragments and their disintegration products.
Roundness analysis of quartz grains shows that the
sandstones of the orthoquartzitic fa-cies accumulated in
shallower water than the lithic wacke facies.
Grain size
distribution analysis shows that the sands of the
orthoquartzitic facies was deposited in an environment
characterized by active reworking.
The environment of deposition of the Siegas Formation
was essentially a continuation of the environment of the
Carys Mills Formation with superposition of a variable
pattern of exogenic deposition.
Turbidite deposits in the
57
lithic wacke facies accumulated on a south-dipping slope
bounded by slopes to the east and northeast.
EA558 was
located in a submarine canyon close to its terminus in the
proximal region of the lithic wacke facies.
The limestone
conglomerates were produced by undercutting and slumping
of the canyon walls.
Sedimentary structures of the sandstones of the orthoquartzitic facies suggest that they were reworked in the
upper flow regime by very active bottom currents on a
shallow shelf.
The sandstones of the arkosic facies
accumulated in quieter, deeper water.
Feldspar ratios and
grain size distribution show that the sands were derived
from the same source material which was fractionated
on the high energy shelf.
The source of the lithic wacke facies was andesitic
volcanic rocks and chert.
The source of the orthoquartzitic
and arkosic facies was quartzose sandstone and salic plutonic
rock with a composition between diorite and granite.
Continual in situ deposition of limestone and slate
occurred in the thesis area through the Late Ordovician and
the Early Llandovery.
In the southern part of the thesis
area there were three significant exogenic events but only
the second, major event affected the shelf and the slope.
On the shelf a high energy environment developed during the
second event.
After the second event both exogenic
deposition and in situ deposition of limestone and slate
were replaced on the shelf by in situ deposition of laminated
58
slate.
This transition took place in the southern part of
the thesis area after the third exogenic event.
The
laminated slates are assigned to the lower member of the
Perham Formation.
It is probable that tectonic uplift of
the shelf margins accompanied the first or second exogenic
events.
Regional aspects of the Siegas Formation will be
discussed later in the thesis (p.
138).
DEFINITION
The "Seigas (Siegas)
Conglornerate"*or "'Seigas Sandstone"
as defined by Nylander (1940, p. 7) included THIO, EM4559, and
outcrops to the east of the thesis area.
TH10 as a type locality for the unit.
Nylander chose
Recent mapping
(Mencher and others, 1963-66, unpublished reconnaissance)
has shown that these outcrops are not part of the same
stratigraphic unit.
The term "Seigas Conglomerate" can only
be applied to the beds at TH10.
It is proposed that the name of the unit represented
be the beds at TH10 be changed from "Seigas Conglomerate"
to "Siegas Formation" and that the type locality
of the unit be changed from TH10 to E1558.
At E4558 the
Siegas Formpion is defined as the succession of sandstones
and associated rocks that overlies beds of the Carys Mills
Formation at TH4 and underlies beds of the lower member of
* "Siegas" is the correct
spelling.
59
the Perham Formation at the east end of E-1558.
The contact
of the Siegas Formation with the lower member of the Perham
Formation is described on page 27 and the contact with the
Carys Mills Formation is discussed below.
DISTRIBUTION AND THICKNESS
The Siegas Formation is of local extent.
Reconnaissance
mapping (Mencher and others, unpublished work) shows that the
formation extends at least 7 miles to the north and northwest
of the thesis area.
to the southeast.
However, the formation is absent 8 miles
The relations to the southwest are
complicated and will be discussed later in the thesis (p.142 ).
Little is known of the geology to the east and northeast of
the thesis area.
The thickness of the Siegas Formation varies from
790 to 350 feet within the thesis area.
(See p.89.)
RELATIONSHIP TO THE CARYS MILLS FORMATION
In the thesis area the contact between the Siegas
Formation and the Carys Mills Formation is exposed at
DR1066, EM323, TH124, TH165, and a11154.
In addition, three
drill cores described by Wright (1945) cross the contact
near EM558.
The base of the Siegas Formation is defined as the base
60
of the lowermost sandstone or conglomerate bed in the section.
At E4323, TH124,
T1165,
and EM1154 there is a gradational
transition from interbedded sandstone and slate of the
Siegas Formation to interbedded limestone, shale, and slate
of the upper limestone member of the Carys Mills Formation.
The basal sandstone bed at DR1066 is 22 feet thick
and overlies interbedded limestone, slate and shale of the
upper limestone member.
Bedding attitudes on either side
of the contact are identical but a definite erosional surface
is present at the contact.
This surface is irregular with
about a foot of relief and repeatedly truncates both an
underlying limestone bed and several laminae in an underlying
shale bed.
About 30 feet of slate have been removed by
erosion at this contact (p. 36).
The thickness of the upper limestone member is 300 feet
(p. 36).
The data of Wright (1945) indicate that near EM665 the
thickness is 121 feet, near TH4 the thickness is 173 feet, and
near EM694 the thickness is 141 feet.
(See Appendix 3, p. 163.)
Analysis of insoluble residue variations in the three sections
show that these values are the result of the removal of parts of
the upper limestone member by erosion.
At a4553 erosional contacts occur at the base of several
conglomerate beds where significant incorporation of the underlying material has taken place (p. 67).
(See Figure 14.)
Submarine erosion was a significant process in the sedimentation
of the Siegas Formation (p.
78).
The Siegas Formation overlies the Carys Mills Formation
with fundamental conformity.
The unconformity at DR1066
and the probable unconformity near EM558 were produced by
submarine erosion during the deposition of the Siegas
Formation.
Regional aspects of the relationship between the Siegas
Formation and the Carys Mills Formations will be discussed
later in the thesis (p. 141).
AGE
Fossils have been found in the Siegas Formation only
in the upper part of the section at EM558.
(See Figure 22.)
The relevant paleontological information is summarized in
Appendix I (p. 155).
In a recent review of the evidence,
Ayrton and others (1969, p. 470) state, "Earlier unpublished
fossil reports by A.J. Boucot and R.B. Neuman (1965) pointed
to an early Llandovery age, which is confirmed by the
present restudy of the collection."
EI558 SECTION
Method of Study
EK558 is a large quarry which exposes most of the
Siegas Formation and the basal beds of the lower member of
the Perham Formation.
With the addition of TH3, a complete
section across beds of the Siegas Formation was chosen
for study.
Each bed in the section was numbered from
Bed 1 at the top of the formation to Bed 458 near the base.
The beds were individually described by a graphic log
technique.
The beds were then divided into as many significant
lithotypes as possible.
Five basic lithotypes were constructed
which included all but three beds of the section.
Each
lithotype occurs throughout the stratigraphic section at
M4558.
Lithotypes
Limestone Conglomerate
This lithotype occurs in beds from 2 to 30 feet thick.
The internal structure of the beds is generally irregular
and occasionally chaotic.
The maximum thickness of any
uniform interval is about five feet.
The beds contain
discontinuous sandstone layers and ellipsoidal lenses
(Figure 11, p. 63).
Some limestone conglomerate beds are
graded and have imbricated clasts at the base of the bed
(Figure 12, p. 64).
Some clasts show interformational
features produced by incorporation and subsequent shattering
of large sheets of limestone within the flow (Figure 13,
p. 65).
Examination of polished sections of the limestone
conglomerate shows that some limestone clasts were semiconsolidated at the time they were eroded.
Erosional
contacts occur at the base of several limestone conglomerate
beds (Figure 14, p. 66).
63
FIGURE I I
SANDSTONE
BODY IN A LIMESTONE
CONGLOMERATE BED
Griswold
The sandstone body occurs in the middle of a 66-inch
thick, graded bed of limestone conglomerate.
is not a clast.
The body
Clasts at the base of the bed are
imbricated (Figure 12).
In this and succeeding photo-
graphs direction 1 points upsection and direction 2
points in
the direction of flow as determined by some
feature in the particular bed.
FIGURE 12
IMBRICATION
AT THE BASE OF
A LIMESTONE CONGLOMERATE
BED
Griswold
The direction of dip of the imbricated clasts
was computed from this and other sections through
the bed.
The direction of original dip is opposite
to the direction of flow determined from paleocurrent
data from EM558 (Figure 24).
described in Figure 11.
The bed is more fully
65
FIGURE
INTERFORMATIONAL
STRUCTURES IN
A LIMESTONE CONGLOMERATE BED
13
Griswold
This photograph is
of the middle of a 27.5-
foot thick bed of limestone conglomerate.
The
arrows point to segments of large limestone
slabs which were evidently taken into the flow
as large sheets and were subsequently broken into
fragments.
66
FIGURE 14
EROSIONAL
CONTACT AT THE BASE OF
A LIMESTONE CONGLOMERATE BED
Griswold
This photograph is of the contact between Bed 20
of the limestone conglomerate lithotype and Bed 21 of the
siltstone lithotype.
Figure 13.
Bed 20 is more fully described in
Laminae in Bed 21 may be traced from the left
side of the picture towards the right where several are
truncated at the base of Bed 20.
Siltstone clasts from
Bed 21 were evidently incorporated into the overlying
flow.
The matrix of the limestone conglomerates is
coarse-
grained lithic sandstone identical to the material of the
sandstone lithotype (p. 69 ).
The clasts range in size from
1/10 to 30 inches and are poorly sorted.
In individual beds
the average clast size is between k and 6 inches.
The
concentration of clasts in the bed increases with increasing
average clast size from 30 to 70 percent.
The clasts are a
mixture of limestone, slate, chert, and mafic volcanic rocks.
The average percentage of limestone clasts increases from
50 percent at the base of the Siegas Formation to about
95 percent at the top.
is the slate.
The only other abundant clast type
Limestone clasts are more poorly sorted and
more angular than any other type.
(See Appendix 4, p. 168.)
The limestone clasts are lithologically identical to the
limestone lithotypes of the Carys Mills Formation (p. 34) and
the Siegas Formation (p. 79).
The slate clasts are dark gray,
noncalcareous to slightly calcareous,
and faintly laminated.
The chert clasts are hard, compact, and either dark gray or
dark green.
The mafic volcanic clasts are fine grained and
contain abundant, small, plagioclase feldspar phenocrysts.
Lateral variations of limestone conglomerate beds were
observed in the quarry.
In Beds 190 to 194 the size and
concentration of the clasts and the thickness of the beds
decrease rapidly to the southwest.
The erosional surface
at the base of Bed 20 varies irregularly across the quarry,
truncating a maximum thickness of 8 feet of the underlying
beds.
The limestone conglomerates are obviously intraformational
and were associated with significant submarine erosion.
The
limestone clasts were derived either from the Carys Mills
Formation or from li-mestone beds of the Siegas Formation.
The
size of the clasts, the thickness of the beds, the abrupt
lateral variations and the occurrence of erosional surfaces show
that sedimentation of the lithotype was a local phenomenon and
that most of the clasts were derived from a local source.
The
roundness contrast between the limestone clasts and the other
clast types indicates a contribution from a second source.
The presence of mafic volcanic clasts shows that this second
source was not in the immediate vicinity.
Mafic volcanic
rocks do not occur within at least 7 or 8 miles of the thesis
area (Miencher and others, unpublished reconnaissance).
The deposition of the limestone conglomerate beds was
a complicated process involving not only incoherent
slumping or creep but also some sort of coherent flow.
Either conditions in the nearby source area or the nature
of the transportation process resulted in a thorough mixing
of the locally derived limestone clasts with volcanic
and chert clasts and abundant coarse-grained sandstone from
a second, more distant source.
Sandstone
This lithotype includes all beds with an average grain
size of fine to coarse sand.
The beds can be divided into
69
a major group of graded sandstones and a minor group of
nongraded sandstones.
The nongraded sandstones occur in
beds from 1 inch to 1 foot thick and are fine grained, light
gray, highly calcareous, and quartzose.
They have a very
low content of lithic grains or feldspar.
Sedimentary
structures of this group are quite variable.
A few beds
have no internal structures or are simply laminated.
Most
of the beds contain abundant cross-lamination and convolute
lamination.
Graded sandstone beds are much more abundant than
nongraded beds.
They can be generally successfully
described by the use of the standard sequence of Bouma (1962,
p. 49).
(p. 70).
An example of a Tb-d sequence is shown in Figure 15
Most of the sequences are truncated and many are
also bottom cut-out.
It was difficult to distinguish a Tc
sequence such as that in Figure 16 (p. 71) from some of the
cross-laminated, nongraded sandstone beds.
The standard
sequence could not be successfully applied to the basal
portions of most of the thicker graded sandstone beds since
grading was not apparent in this part of the bed.
massive, nongraded part of the bed below the
will be referred to as the
sub-a
a
The
interval
interval.
The graded sandstone beds are 2 inches to 30 feet thick.
The sandstone is fine to coarse grained, dark to medium
gray, slightly calcareous, lithic, and feldspathic.
The beds
less than about five feet thick were adequately described by
the standard sedimentation sequence.
The base of the
a
70
FIGURE 15
A GRADED BED
OF THE SANDSTONE
LITHOTYPE
Griswold
The bed is graded from a medium-grained sandstone at
the base of the bed to a siltstone at the top.
The
top of the bed is difficult to define and distinguish
from the overlying shale bed.
of Bouma (1962) are present.
Intervals b, c and d
FIGURE 16
CROSS-LAMINATION
IN A GRADED
SANDSTONE BED
1I
Griswoltd
The bed is slightly graded from the bottom to the
top of the bed within the fine-grained sandstone range.
Interval c of Bouna (1962) makes up the whole bed.
The cross-laminated units are trough forms and are
generally heavily eroded.
been preserved.
Some stoss-side laminae have
interval contains discontinuous, poorly defined bodies of
limestone conglomerate and siltstone.
The sandstone at the
base of many a intervals is very poorly sorted and contains
-inch grains of limestone.
The sub-a interval is conspicuous in beds greater than
five feet thick and accounts for the bulk of beds ten to
thirty feet thick.
The sandstone is coarse grained and
relatively well sorted.
interval.
No grading was observed in the
The sub-a interval is uniform and homogeneous
with the exception of a few exotic limestone boulders up
to 2 feet in diameter which occur well above the base
of the bed.
In some beds poorly defined lamination occurs
near the top of the sub-a interval.
Sole features occur on most exposed bottom surfaces
of graded sandstone beds associated with the sub-a, a, b,
or c intervals.
These include load casts (Figure 17,
p. 73), large tool marks (Figure 18, p. 74), flute casts
(Figure 19, p. 75), and groove casts (Figure 20, p. 76).
Tool marks are generally more abundant than either load
or scour marks.
Other sedimentary features of the graded
sandstones include ripple marks (Figure 18) and parting
lamination (Figure 21, p. 77).
The major factor in the sedimentation of the sandstone
lithotype was turbidite deposition.
The nongraded sandstones
were probably produced by the action of normal bottom
currents.
The abundance of limestone grains at the base
of many a intervals suggests that the turbidity currents
73
FIGURE /7
LOAD CASTS
AT THE BASE OF
A GRADED SANDSTONE
BED
Grievold
This photograph is of the bottom surface of
Bed 1 of the sandstone lithotype.
The prominent sole
features are large load casts with about three inches
of relief.
Small flute and groove casts occur in the
lower right corner of the picture.
Bed 1 is graded
from a coarse to a fine-grained sandstone and is made
up of the a interval of Bouma (1962).
about 16 inches thick.
The bed is
74
FIGURE 18
LARGE TOOL
MARKS ON THE BASE OF
A GRADED SANDSTONE BED
Griswold
This photograph is of the bottom surface of a
graded sandstone bed.
The large irregular lipear
structures on the bottom surface are ridges with a
relief of
to two inches and are probably tool marks
where the irregularities and bifurcations of the casts
are due to rotation of a large irregular tool in the
flow. On the same surface are casts of ripple marks of
an underlying sandstone bed.
75
FLUTE CASTS
ON THE BASE OF
A GRADED SANDSTONE BED
FIGURE
19
Griswold
This photograph is of the bottom surface of
a graded sandstone bed between Bed 200 and Bed 250.
The flute casts here have similar shapes and
arrangements as most other flute casts at
but are unusually large.
m558
76
FIGURE 20
GROOVE CASTS
ON THE BASE OF
A GRADED SANDSTONE BED
Griswold
This photograph is of the bottom surface of
Bed 138 of the sandstone lithotype.
The bed is ten
inches thick and is graded from top to bottom of the
bed from fine- to medium-grained sandstone.
a interval of Bouna (1962)
is present.
Only the
The main
groove cast has about 0.2 inches of relief.
Smaller
groove casts and low relief, symmetrical, isolated
flute casts are abundant.
77
FIGURE 2/
PARTING
LAMINATION IN THE INTERIOR OF
A GRADED SANDSTONE BED
Griswold
This photograph is of an interior surface parallel
to bedding of Bed 10.'
The bed is
about 18 inches thick
and is graded from a fine-grained sandstone at the top
of the bed to a fine-grained gravel at the base.
the a interval of Bouma (1962)
is present.
Only
The
paleocurrent direction is the same as others from EM558
(Figure 24).
were able to erode semi-consolidated limestone and that
normal turbidite deposition was genetically associated with
the sedimentation of the limestone conglomerates.
The features of the sub-a intervals are generally
similar to those of the "mass-flow deposits" of Stauffer
(1967, p. 491) and the "proximal turbidites" of Walker
(1967, p. 30).
The general absence of limestone clasts
in these intervals suggests that deposition was not
accompanied by erosion of the underlying beds.
The uniformity
of grain size and the presence of suspended exotic boulders
are similar to features of the "sand flows " of the San
Lucas Canyon (Shepard, 1964, p. 168).
However, the sub-a
interval is not graded and is always associated with intervals
of the normal turbidite sequence.
Siltstone
This lithotype includes siltstone, shale, and slate
and occurs in beds from 1 to 15 inches thick.
Obscure
tracks attributed to benthonic organisms occur on the
upper surfaces of some siltstone and shale beds.
Most beds are slate and can be roughly separated into
laminated and nonlaminated varieties.
Nonlaminated slate
is most abundant near the base of the Siegas Formation and
laminated slate is most abundant near the top.
micaceous, calcareous, and dark gray.
types.
The common laminae are
The slate is
Laminae are of two
- to 1-inch, indistinct
79
segregations of very dark gray siltstone which are
regularly spaced at 2- to 3-inch intervals in the slate
beds.
The slate weathers dark greenish gray and the
laminations weather light greenish gray.
laminae are 1/8- to
-inch,
The less common
distinct segregations of
light gray, highly calcareous, coarse-grained siltstone
which are irregularly spaced at k- to 6-inch intervals in
the slate beds.
These laminae may be internally laminated
or cross-laminated.
Limestone
The beds assigned to this lithotype are identical in
all respects to beds of the limestone lithotype of the
Carys Mills Formation (p. 34).
Chert
The 12 beds assigned to this lithotype range from 3
to 15 inches in thickness.
The chert is dark gray, noncalcareous,
and aphanitic.
Stratigraphic Succession
Characteristics of the stratigraphic succession at EM1558
are presented in Figure 22 (p. 80).
The average bed thickness
and the abundances of the lithotypes are plotted against bed
80
VERTICAL
FIGURE 22
LITHOLOGIC VARIATIONS OF THE
SIEGAS FORMATION A T EM558
B
UBER
4T 0
T/ ONz
e
-4
L - 4.--
-~~
s -. el._-
-+-.
-.--
~s
16
~ ~~~~~~
up..
2-()6
-
7 V
-
.-
- ...s -.-.
--.-
...
=.-.
.--
-
-
20+
---
....-
.
.aa
-
-
--
i-
-
-
-
--
ULA ESTRATIGRAPHIC
THIKNESS
NJFRE1
* -fossil oceldy
-moving cverdge of bed thickness
n -movinq averaqe of freqency of occurrnce(7-bed intet-vaIJ
81
number to reduce the effect of the differences in
sedimentation rates of the lithotypes on the assemblage.
t is the moving average of bed thickness over a 7-bed
interval.
If k
is the bed number, then
k'=k+3
E(k) = 7tk'
k'=k-3
where tk' is the thickness of the k'th bed.
n
is the moving
average of the number of beds of a particular lithotype in a
7-bed interval.
For a particular lithotype j,
k'=k+3
nj (k)
(k')
=ij
k'=k-3
where i is
the lithotype of the k'th bed.
t is measured in
feet and A has a range from zero to seven.
The distributions of bed thickness, sandstone abundance,
and limestone conglomerate abundance are closely associated
and the distributions of limestone abundance and siltstone
abundance are associated.
These two groups represent two
fundamentally different types of sedimentation.
The
sedimentation of the sandstones and limestone conglomerates
will be referred to as exogenic deposition and the sedimentation
of the limestones and siltstones will be called in situ
deposition.
The in situ deposition would be expected to produce a
succession of thinly interbedded limestone and slate.
This
82
assemblage can be observed in certain parts of EM558.
The
lithotypes and the assembly produced by this type of
deposition are identical to those of the Carys Mills Formation
(p. 33).
In situ deposition of the Siegas Formation was a
continuation of the sedimentation of the Carys Mills
Formation.
The exogenic deposition occurred in three distinct
sedimentary events.
The second, major event was a
transgressive-regressive sequence of turbidite deposition
beginning and ending with distal conditions and passing
through a proximal phase.
This sedimentary event was
initiated by mixed deposition of thinly bedded turbidites
and nongraded sandstones introduced by normal bottom
currents.
(Beds 308-396.)
This phase was followed by an
increase in thickness and abundance of turbidite deposits
associated with active submarine erosion and the production
of limestone conglomerates (Beds 264-307).
The cumulative
phase was the mixed deposition of "sand flows" and normal
turbidites and was probably not accompanied by submarine
erosion (Beds 239-263).
A regressive erosional phase
followed (Beds 184-238) which was in turn followed by the
final regressive distal phase of mixed turbidite and bottomcurrent deposition (Beds 84-183).
The stratigraphic succession at U4558 was produced by
the superposition of three events of exogenic deposition on
a process of in situ sedimentation which was a continuation
of that of the Carys Mills Formation.
83
Modal Anays
of Sandstones
Petrographic modal analyses were made on 32 samples from
E24558 using a point counting technique.
All of the samples
were medium grained sandstone from graded sandstone beds.
The analytic technique, petrographic species, and individual
samples are described in Appendix 5 (p. 171).
All of the
samples are either lithic wackes or lithic arenites according
to the system of Williams and others (1963, p. 292-293).
The
variation of sandstone composition with bed number is presented
in Figure 23 (p. 84).
The relative absence of data between
Beds 20 and 180 and between Beds 300 and 440 is a result of
the finer grain size of the sandstones of these regions.
The
high variability of data in the central region is probably
only a result of abundant analyses.
Sandstone composition shows relatively little variation
across the section.
It is possible that the more proximal
phases have a higher total lithic content than the distal
turbidites.
Such a feature could be the result of lateral
segregation within the turbidity flow.
The constancy of
composition suggests that the nature of the source area
remained constant throughout the time of deposition of the
formation.
The results of modal analyses from the entire Siegas
Formation will be considered later in the thesis (p. 90).
FIGURE 25
VARIATION OF
SANDSTONE COMPOSITIONS OF THE
SIEGAS FORMATION AT EM558
60
_O
T
I
t
i
T
N
130
IT
-L
.L
-L.-
z920~
0
f
10
A JOC LA
TO T
E- FEL S P 'R
P'OTA
CLSPAC
L
--
volume percen+ abunddnce of species
20o
85
Paleocurrent Analysis
Paleocurrent information was taken from EM558 from 60
graded beds of the sandstone lithotype.
The readings included
38 measurements of flute cast orientation, 23 measurements on
groove casts and other tool marks, five readings on ripple
marks and one measurement of parting lamination.
The results
of these readings are presented in Figure 24 (p. 86).
It is
assumed that the tool marks and the parting lamination were
produced by motion in the same direction as indicated by flute
casts and ripple marks.
The beds from which readings were taken
occur throughout the section at EMI558.
No correlation exists
of direction with type of sedimentary structure or bed number.
Turbidite sedimentation at
4558 was characterized by
a highly uniform direction of transport.
This shows that the
relative position of the immediate source of the turbidites
and E1558 was highly stable throughout the time of deposition
of the Siegas Formation and suggests the possibility of
channelled flow.
The generally proximal nature of turbidite
sedimentation at EM558 indicates that the paleocurrent
direction parallels the paleoslope.
The depositional surface
at E 558 duringthe sedimentation of the Siegas Formation
was stable and dipped to the south.
The source of the
exogenic sediments at EM558 was somewhere to the north of
the thesis area.
The accuracy of paleocurrent readings is largely dependent
on the practicability of unfolding the deformed beds to recover
86
PALEOCURRENT
FIGURE 24
DIRECTIONS FROM SANDSTONES OF
THE SIEGAS FORMATION AT EM558
N
w.
E
P -
NUMBER
OF READINGS
FLOW FROM THE NORTH
"-i's
87
the original orientation of the depositional surface.
Later
structural analysis (p.13 5 ) shows that the unfolding process
is possible at EM558.
FACIES VARIATIONS
Stratigra
c Variations
The lithotypes of the Siegas Formation in the thesis area
are similar to those at EM558.
The chert lithotype has not
been found outside of EX558, but this is probably due to the
scarcity of the lithotype and poor exposure.
Limestone and
siltstone lithotypes in the thesis area are abundant and
identical to those at EM558.
Limestone conglomerates occur only
at EM559, DR1021, TH411, and TH412 and appear to be most abundant
at E4558.
The sandstone lithotype is abundant in the thesis
area but its characteristics are variable.
A minor group of
nongraded highly calcareous sandstones similar to those at
R,1558 occurs throughout the thesis area.
The major group of
thickly bedded sandstones is also present but-the sandstones may
be quite different from those at a4558.
The differentiation of sedimentation into exogenic and
in situ deposition established at E4558 can be applied
throughout the thesis area and it is probable that in situ
deposition was relatively uniform over the thesis area.
changes in the Siegas Formation are the result of radical
changes in exogenic deposition.
Facies
The stratigraphic variations produced by changes in
exogenic deposition are summarized in Figure 25 (p. 89).
The horizontal datum for this figure is bedding at the base
of the lower member of the Perham Formation.
The thickness of
the Siegas Formation is well known at the E4558, DR1067, TH116,
and EM11154 sections.
The thickness decrease between the MA558
and the DR1067 sections is due to the rapid disappearance of
the limestone conglomerate lithotype in a southward direction.
Beds of the sandstone lithotype thin both to the south and the
east.
The decrease in thickness between the DR1067 and the
TH116 sections is mainly the result of this gradual thinning
of the sandstone beds and the disappearance of the lower
sandstone unit which corresponds to the first exogenic event
recognized at E553.
At the TH116 section the upper sandstone
unit (third exogenic event) is made up of thin beds of highly
calcareous nongraded sandstone.
The thickness decrease
between the TH116 and the EA1154 sections is due mainly to the
disappearance of the upper sandstone unit.
In this section the
interval of in situ deposition between the two sandstone units
cannot be recognized and the contact with the lower member of
the Perham Formation must be placed at the top of the major
sandstone unit.
A few very thin, highly calcareous, nongraded
sandstone beds of the lower member of the Perham Formation at
EX1152 may be correlatives of the upper sandstone unit of the
Siegas Formation.
The data of the next section will show the extent to
which the process of exogenic deposition at EX558 is applicable
low
FIGURE 25
kO FEET
1w
qw,
I
lqw-
11
11-1
-
SCHEMATIC CROSS-SECTION
THE SIEGAS FORMATION
NW
__
_
_
__
_
OF
NE
_
1
-100
-200
k5
H9
1600W
-300
TH292
M1164...
D
400
\500
-H2
-EM560EM23
-
-
TH3MILES
2
00
6
-MAINLY SANDSTONE AND SLATE
S-MAINLY LIMESTONE AND SLATE
-OUTCROP
DTH2
CONTROL IN THE SIEGAS
THE SECTION L INE IS
SHOWN IN FIGURE 26
-LIMESTONE CONGLOMERATE
FORMATION
90
to the Siegas Formation as a whole.
However, the rapid
disappearance of the limestone conglomerates and the thinning
of sandstone beds south from EM558 is consistent with the
nature of deposition of the lithotypes (p. 68, 72 ) and
suggests that the south-dipping paleoslope extended through
the southwestern part of the thesis area.
Variation of Sandstone Compositions
Modal analyses were done on 67 samples of the sandstone
lithotype from the Siegas Formation including samples from
EX558 (p.
83).
A complete description of the method of
analysis, petrographic species, and the individual samples is
given in Appendix 5 (p. 171).
In an effort to reduce the
effect of vertical variation the results were averaged into
groups defined on page
183.
The average compositions of
these groups were classified according to the system of
These results
Williams and others (1963, p. 292-293).
(p. 183) were used to define three facies of the Siegas
Formation which are laterally equivalent.
The lithic wacke
facies (Figure 26, p. 91) includes only groups with average
compositions of lithic wacke.
The arkosic facies includes
arkosic wackes and arkosic arenites.
facies is made up of quartz arenites.
The orthoquartzitic
Feldspathic arenites
such as occur at Groups E and J are transitional phases.
Obviously the nature of exogenic deposition found at Ei558
can only be applied to the lithic wacke facies.
91
FACIES
FIGURE 26
OF THE SIEGAS FORMATION
*L -GROUPS AS
DEFINED IN
A PPENDIX 5
SECTION LINE
FOR FIGURE 25
e
~f
THYS
92
On the basis of stratigraphic variations (p. 89) the
lithic wacke facies may be divided into a proximal region
including groups A through D and a distal region including
groups F through I.
The lateral variation of the abundance of total quartz in
the sandstones is presented in Figure 27 (p. 93).
Quartz
abundance distinguishes the orthoquartzitic facies from the
other two facies and indicates that the facies was a local
source of quartz.
The variation of plagioclase abundance is presented in
Figure 28 (p. 94).
Plagioclase abundance does not characterize
any of the facies which suggests that plagioclase was derived
form more than one local source.
The maximum in the diagram
is related to the direction of paleocurrent transport
established at E4558 (p. 85) and implies that the lithic wacke
facies was a major local source of plagioclase.
It is also
possible that the other facies were local sources.
The variation of potassium feldspar abundance is
presented in Figure 29 (p. 95).
Potassium feldspar
abundance distinguishes the arkosic facies from the other two
and indicates that the arkosic facies was the local source
of the species.
Some potassium feldspar was dispersed into
the distal region of the lithic wacke facies.
The variation of total salic plutonic content is
presented in Figure 30 (p. 96).
The distribution is identical
to that of the total potassium feldspar which indicates that
the arkosic facies was the local source of salic plutonic
93
VARIATION OF
FIGURE 27
TOTAL QUARTZ IN SANDSTONES
OF THE SIEGAS FORMATION
IJ
-
GROUP AS
DEFINED IN
APPENDIX 5
33.5 - AVERAGE PER
CENT A BUNDANCE
OF TOTAL QUARTZ
e
~
1HS
94
VARIATION OF
FIGURE 28
PL AGIOCLASE FELDSPAR CONTENT
IN THE SIEGAS FORMATION
OF - GROUPS AS
DEFINED IN
APPENDIX 5
6.7 -AVERAGE PER
CENT CONTENT OF
PLAGIOCLASE
FELDSPAR
r1s
95
VAR/ATION OF
FIGURE 29
TOTAL POTASSIUM FELDSPAR
IN THE SIEGAS FORMATION
OP - GROUPS AS
DEFINED IN
APPENDIX 5
2.3 - AVERAGE PER
CENT CONTENT
OF POTASSIUM
FELDSRAR AND
PER THI TE.
\*\
*,
Nm%
~
~
>)\
TIES
96
VARIATION OF
FIGURE 30
TOTAL SALIC PLUTONIC CONTENT
IN THE SIEGAS FORMATION
AS
DEFINED IN
eJ - GROUPS
APPENDIX
5
3.2-AVERAGE PER
CENT CONTENT
OF SALIC
PLUTONIC GRA INS
N
m
am
am ourn
a
am
m
a
am
am
a
TIIS
fragments and that the potassium feldspar was derived from
the disintegration of salic plutonic rocks.
The variation of the abundance of mafic volcanic
fragments is presented in Figure 31 (p. 98).
The abundance
characterizes the lithic wacke facies and shows an obvious
relation to the proximal-distal variation across the facies.
The proximal region of the lithic wacke facies was the local
source of mafic volcanic fragments.
The variation of the content of limestone grains is
shown in Figure 32 (p. 99).
Abundant limestone grains
characterize the proximal region of the lithic wacke facies.
The maximum in the diagram is
clearly related to the
paleoslope (p. 90) and indicates that the local source
of the limestone grains was in the proximal region or to
the north or northwest of E4558.
The variation of pyroxene abundance is shown in Figure 33
(p. 100).
Pyroxene abundance bears the same relationship to
the lithic wacke facies as does the limestone abundance.
The proximal region of the lithic wacke facies was the
local source of both the pyroxene and the limestone grains.
The lithic wacke facies was the local source of
mafic volcanic fragments, some plagioclase, pyroxene and
limestone fragments.
Previous considerations (p. 68)
show that the limestone was locally derived by submarine
erosion.
Petrographic observations suggest that some of the
plagioclase and all of the pyroxene are disintegration
products of mrafic volcanic rocks.
(See Appendix 5,
98
VA R 1A TION OF
FIGURE 3
MAFIC VOLCA NICS IN SANDSTONES
OF THE SIEGAS FORMATION
oH -GROUPS AS
DEFINED IN
APPENDIX 5
PER
CENT CONTENT
OF MAFIC
VOLCANIC GRAINS
17.6 - AVERAGE
e
K\
d
4~~q
T4Ii
99
FIGURE 32
VARIATION OF
LIMESTONE CONTENT OF SANDSTONES
OF THE SIEGAS FORMATION
eG - GROUPS AS
DEFINED IN
APPENDIX 5
0.3- AVERAGE PER
CENT CONTENT
OF LIMESTONE
GRAINS
0~
100
VARIATION OF
FIGURE 33
PYROXENE CONTENT OF SANDSTONES
OF THE SIEGAS FORMATION
-
*C
GROUPS
AS
DEFNED
IN
APPENDIX 5
/.0 - AVERAGE
PER
CENT CONTENT
OF PYROXENE
*\
~
'x\
1
~v'
#4~ \~.\
m
am
o0
2r
.
101
p. 174).
The distributions of these species suggest that
material from the lithic wacke facies was not dispersed into
either the arkosic or the orthoquartzitic facies but was
transported south across the facies from some region to the
north or northwest of the thesis area.
The arkosic facies was the source of salic plutonic
fragments, potassium feldspar and some plagioclase.
Petrographic considerations suggest that the feldspars may
have been derived from the disintegration of salic plutonic
rocks with a composition between diorite and granite.
The
distributions of the species suggest that sediment was
dispersed from the arkosic facies into the distal region of
the lithic wacke facies.
This suggests that the local
paleoslope dipped with a major component to the southwest and
that the distal region of the lithic wacke facies was in
deeper water than the arkosic facies.
The orthoquartzitic facies was the major local
source of quartz.
This quartz was probably dispersed into
both of the other facies but since the mafic volcanic rocks
and salic plutonic rocks were also quartz sources (p. 175,
176
) the quartz balance is more complicated.
Roundness Distribution Analysis
The roundness of quartz grains from sandstones of the
Siegas Formation was investigated by point-counting 50 grains
of medium sand size in each of four thin sections which were
102
also used for modal analysis (p. 179
,
180).
Each grain was
assigned a roundness value on Power's charts (Folk, 1965,
p. 11) where the roundness decreases on a scale from six to
zero.
The results are presented as histograms in Figure 34
(p. 103).
Samples TH294 and TH304 are from sandstones of the
orthoquartzitic facies.
Samples EM558-15 and EM558-74 are
from sandstones of the lithic wacke facies.
The quartz of the orthoquartzitic facies is a homogeneous
rounded assemblage.
The quartz of the lithic wacke facies is
a mixture of a homogeneous rounded fraction similar to the
quartz of the orthoquartzitic facies and a very angular
fraction.
Petrographic work shows that the quartz phenocrysts
of the mafic volcanic fragments of the lithic wacke facies
are also very angular (p. 175).
Medium-grained rounded quartz was probably transported
from the orthoquartzitic facies into the lithic wacke facies
but angular quartz was not transported in the reverse
direction.
This suggests that the paleoslope between the
two facies dipped with a major component to the west and that
the orthoquartzitic facies accumulated in shallower water
than the lithic wacke facies.
Grain Size Distribution Analysis
The grain size distributions of sandstones of the Siegas
Formation were investigated by analyzing ten thin sections
that were previously used for modal analyses (p. 179-180 ).
103
FIGURE 34
ROUNDNESS OF
QUARTZ OF SANDSTONES
OF THE SIEGAS FORMATION
40-
4
TH294
TH304
30-
30-
10-%20-
00
6p
0p
EM558 BED NUMBER /5
EM558
30-
30
/0-
/0
S2
Op
p
-
BED NUMBER
74
0
p
ROUNDNESS (POWERS' SCALE)
Tys
104
The analysis was done by counting 100 points for each thin
section and measuring the size of the grain at each point
by Martin's diameter (El-Hinnawi, 1966, p. 23), placing the
grain size between limits based on the micrometer eyepiece
of a microscope.
The smallest size limit was 0.031 mm.
Van der Plas (1962) has observed that a point counting
procedure leads only to qualitative information.
The results
of the analyses are given in Figure 35 (p. 105).
of the
samples; TH109-1, TH109-2, and TH124 are from the arkosic
facies; TH116, TH294, and TH304 are from the orthoquartzitic
facies; E4558-8, TH558-74, and EM558-231 are from the lithic
wacke facies, and TH181-1 is from the transitional area.
It can be calculated that for the arkosic facies an
average of 11 percent of the grains are coarser than 2$ where
corresponding figures are 29 percent for the orthoquartzitic
facies and 38 percent for the lithic wacke facies.
While
these numbers are not quantitatively significant, it is clear
that the arkosic facies is depleted in coarse grains with
respect to the other two facies.
Since the samples of the
arkosic facies were the coarsest that could be found, this
finding is
probably not a product of biased sampling.
An independent aspect of grain size distributions can
be examined by considering the variation of matrix abundance
as determined by modal analyses.
(See Figure 36, p. 106).
The orthoquartzitic facies is distinguished from the other
two facies by the scarcity of fine-grained matrix.
The
relative depletion suggests either that the immediate source
FIGURE 35
GRAIN SIZE DISTRIBUTIONS OF
SANDSTONES OF THE SIEGAS FORMATION
4
*
EM558 BED
30
NUMBER 8
40
30
20
20
/0
/0
EM558 BED
4
o
NUMBER
30.
74
EM558
BED
NUMBER
231
40
%
40
THI8-I
THIO9-I
30
30-
20
--
20
./a/-
-0
I
~
0/
TH304
-
0.
4040
TH109 -2
30
O
THI
-
414
o
TH124
TH294
30-
3
2
/0.
/0
00
0-
/0
/0
0
1234-
ANALYSIS TERMINATED AT 5#.
%
- VOLUME
PERCENT(SEE
TEXT)
Hs
106
36
MATRIX VAR IA TION
IN SANDSTONES OF
THE SIEGAS FORMATION
FIGURE
*A-
GROUPS AS
DEFINED IN
APPENDIX 5
6.3-
AVERAGE PER
CENT CONTENT
OF MATRIX
107
of the quartz arenites was also depleted in matrix material
or the mechanism of deposition in the facies was effective
in the removal of fine-grained material.
Considering the
general availability of fine-grained material in the Siegas
Formation, the second alternative is more likely.
ENVIROZMIENT OF DEPOSITION
Sedimentation of the Siegas Formation was characterized
by uniform in situ deposition of limestones and slates
identical to those of the Carys Mills Formation.
The essential
features of the environment of the Carys Mills Formation
(p. 51) were also characteristics of the environment of the
Siegas Formation.
The presence of organic markings (p. 78)
suggests that benthonic life was possible at least at EN1558.
A highly variable pattern of exogenic sedimentation was
superposed on the environment of in situ deposition.
In the
lithic wacke facies turbidite deposition varied from a distal
region in the south to a highly proximal region in the
northwest.
The paleoslope dipped to the south and was
bordered by other slopes to the east (p. 101, 102).
The
turbidites moved from north to south across the facies from
somewhere north of the thesis area.
The general abundance of
matrix and angularity of grains of the deposits indicate- that
most of the sediments were not reworked.
However, normal
bottom currents were active in resedimentation of fine-grained
quartzose sand.
108
Several features indicate an unusual environment at the
most proximal end of the lithic wacke facies.
The distributions
of limestone grains, limestone conglomerates and pyroxene
suggest dispersion from a restricted source located slightly
to the northwest of E558.
The uniformity of paleocurrent
directions at EM'558 is suggestive of some sort of channelled
flow.
The abundance of limestone conglomerates and removal
of as much as 170 feet from the Carys Mills Formation (p. 60)
suggests an environment of active deep erosion by turbidity
currents and transportation of the eroded material (p. 68).
These are features expected or observed in modern submarine
canyons (i.e., Shepard, 1964, 1965).
EM558 was located in the
channel of a submarine canyon possibly close to its terminus
at a submarine fan in the south-central part of the thesis
area.
The thick limestone conglomerate beds were produced by
slumping of the steep walls of the canyon.
The sandstones of the orthoquartzitic facies have probably
been thoroughly reworked (p. 107).
No sedimentary structures
have been found in these sandstones, even by acid etching of
polished surfaces of samples.
The average grain size of the
sandstones is on the order of 0.3 mm.
For this grain size
reworking produces ripple and dune structures up to flow
velocities of about 1 meter per second.
1963, p. 291).
(Simons and Richardson,
Above this approximate velocity the deposition
of a structureless bed may take place (Simnons and others, 1965,
p. 44).
In order to wipe out previous sedimentary structures
it is only necessary that flow velocities in the environment
109
rise to such high values from time to time.
Velocities on
the order of meters per second are observed today in shallow
shelf environments with very active tidal currents (Seibold,
1963, p. 44).
The sandstones of the orthoquartzitic
environment were probably deposited on such a shelf.
In contrast, the sandstones of the arkosic facies are
crossbedded which suggests they accumulated in a more sheltered
environment.
The arkosic and the orthoquartzitic facies were
both deposited in shallower water than the lithic wacke facies
(p. 101, 102).
closely related.
The source material of the two facies are
While the relative abundances of the
feldspars would be greatly affected by the contrast in
sedimentary environment, the ratio of total potassium feldspar
to plagioclase should be largely independent of environment
and be more closely related to source material.
The average
ratio for the orthoquartzitic facies is 5.4, for the arkosic
facies is 6.3, and for the lithic wacke facies is 0.9.
Evidently the sandstones of the orthoquartzitic and the
arkosic facies were derived from the same immediate source
material.
The differences between the two facies are due
mainly to sedimentary environment.
The finer grain size of
sandstones of the arkosic facies, the environment of the
orthoquartzitic facies and the derivation from a common source
material all suggest that the arkosic sediment was winnowed
from the orthoquartzitic sediment on the shelf and deposited
in deeper, quieter water on a slope to the east of the lithic
wacke facies.
110
A simplified model of the environment and the transport
directions deduced from dispersal of the petrographic species
and paleocurrent information is shown in Figure 37 (p. 111).
PROVENANCE
Sandstones of the lithic wacke facies contain locally
derived limestone grains, mafic volcanic fragments and their
disintegration products.
Limestone conglomerates contain
locally derived limestone and slate clasts and rounded chert
from so-ne other source.
(See Appendix 4, p. 168.)
A source
of andesitic volcanic rocks (p. 175) and chert accounts for
all exogenic components of the lithic wacke facies not
derived from the immediate vicinity of the thesis area itself.
Sandstones of the orthoquartzitic facies and the arkosic
facies had the same local source material (p. 109) and the
compositions of the arkosic sandstones show that a significant
part of the ultimate source was salic plutonic rock (p.
101).
However, the well-rounded quartz of the orthoquartzitic facies
is most probably polycyclic and derived in part from older,
quartzose sedimentary rocks.
The local source material of
the orthoquartzitic and the arkosic facies was probably
quartzose, feldspathic detritus produced by mixing of
erosion products of quartzose sandstones and salic plutonic
rocks with a composition between diorite and granite.
Regional aspects of the provenance will be considered
later in the thesis (p. 145).
111
FIGURE 37
SEDIMENTARY
TRANSPORT AND ENVIRONMENT
OF THE SIEGAS FORMATION
DIRECTIONS OF
SEDIMENTARY
TRANSPORT. THE
SIZE OF THE
SYMBOLS SHOWS
THE RELATIVE
IMPORTANCE OF
THE DIRECTIONS.
.~ *
~
~f
xw
No
mn
0
a
xw
1.
4uw mmoom1-
112
DEPOSITIONAL HISTORY
In the late Ordovician interbedded limestone, shale and
slate of the Carys Mills Formation accumulated in relatively
quiet, stagnant to poorly aerated water on a stable paleoslope
dipping to the south.
In the earliest Silurian turbidite
deposition began in the lithic wacke facies, associated with
erosion of a submarine canyon in the EM,558 region and possible
tectonic uplift of shelf margins.
37.)
(Contrast Figures 10 and
At this time no sandstone was accumulating on the
developing shelf and slope.
A decrease in exogenic sedimentation
permitted the continuation of limestone and slate sedimentation
over the whole thesis area.
A major exogenic interval
followed culmunating in "sand flow" deposition in the EM558
area.
At this time quartzose, feldspathic sediment was
deposited on the shelf, which had developed a highly active
bottom current system.
This sediment was continually
resedimented, separating a finer grained fraction that was
deposited in deeper, quieter water on the slope.
Another
decrease in exogenic deposition followed the major exogenic
interval in which in situ deposition of limestone and slate
continued in the southern and western parts of the thesis
area.
In the northeastern part of the thesis area there was
only deposition of laminated slate.
The third and final
exogenic event produced some erosion in the EM1558 area and
turbidite deposition in the lithic wacke facies but had very
little effect on the shelf and slope.
This was followed all
113
over the thesis area in the late Early or Middle Llandovery
by deposition of the laminated slates of the lower member
of the Perham Formation.
Even at this time steep slopes
persisted in the E4558 region (p.
29).
114
STRUCTURAL GEOLOGY
SUMARY
Regional interpretation of northeastern Maine and
vicinity shows that the area was last severely deformed in
the Early to Late Devonian by the Acadian orogeny.
Parts
of the area were also deformed in the Middle Ordovician to
Early Silurian by the Taconic orogeny.
During this event
the thesis area was located near a tectonic front between
regions of quiescence and deformation, so the structural
effects of the orogeny would probably have been minor.
Field analysis shows that the main structural feature
of the thesis area is a grossly homogeneous system of tightly
appressed, symmetrical, similar folds.
Poorly defined, post-
kinematic, small-scale faults are also abundant.
Nonplane,
noncylindrical folding appears to be restricted to the
mesoscopic scale at areas of macroscopic fold closure.
Stereographic analysis of temporal domains of bedding
shows that the fold system of Silurian units and the Carys
Mills Formation is homogeneous, tightly appressed, plane,
cylindrical, similar and symmetrical.
Lake Formation are
Folds in the Madawaska
asymetrical, inclined, and noncylindrical.
The structural contrast between the Madawaska Lake Formation
and younger units is probably expressed as a disharmony
involving basal beds of the Carys Mills Formation.
Stereo-
graphic analysis of cleavage shows that all cleavage in the
115
thesis area was formed by the same process that produced
the symmetrical,
sylindrical fold system.
Tectonic interpretation of the symmetrical fold system
shows that the bulk deformation of the thesis area occurred
during the Acadian orogeny by the generation of a homogeneous
system of plane,
cylindrical,
tightly appressed,
symmetrical,
similar folds with an axial plane of N43E87N and an axis
striking S43W and plunging 2 degrees.
The inclination and
the plunge are related to the morphology of regional structures.
The Acadian orogeny also produced a homogeneous cleavage system
symmetrically distributed with respect to the axial plane of
folding.
The axes of the pure-strain ellipsoid can be
deduced from the fold symmetry but the production of rotational
strain components by regional tectonic movements indicates that
the results are only of local significance.
The upper member
of the Perham Formation and the Siegas Formation were deformed
mainly by flexural-slip folding which indicates that the beds
of these units can be realistically "unfolded."
The lower
member of the Perham Formation and the Madawaska Lake
Formation were deformed by slip or shear folding.
Lack of
knowledge of the mechism of bulk deformation of the thesis
area makes the construction of palinspastic maps impossible.
The structural style of the Madawaska Lake Formation
was not produced by the homogeneous strain associated with
Acadian folding.
Local stress-perturbation within the
formation probably cannot account for observed
structures.
Some unknown structures in the Madawaska Lake
116
Formation predated the Acadian orogeny.
It is the writer's
judgment that they were the product of low-intensity
folding in the Taconic orogeny associated with the
development of shelf margins in the thesis area.
The thesis area during the Taconic orogeny was
characterized by mild folding at shallow depths, evolution
of shelf margins, and continuous sedimentation.
The Taconic
orogeny to the north of the thesis area can be tentatively
dated as Early Llandovery to early Early Llandovery.
RFGIONAL SETTING
Most of northeastern Maine, northwestern New Brunswick
and adjacent parts of Quebec were last severely deformed in
the Early to Late Devonian by the Acadian orogeny (Boucot
and others, 1964, p. 93-94).
Parts of the same area were
deformed with similar intensity during the late Ordovician
or early Silurian by the Taconic orogeny (Pavlides and others,
1968).
The thesis area was located near the western margin
of the Aroostook-Matapedia trough, a stable basin that
continuously received sediment from the late Middle Ordovician
through the Early Llandovery (Berry,
1963,
p.
31).
Paleontological data imply the existence of a conformity
during this time in northwestern New Brunswick about forty
miles ot the northeast of the thesis area (Ayrton and others,
1969, p. 475).
Conformable relationships are also suggested
117
by fossil ages in the Presque Isle-Caribou area some twentyfive miles south of the thesis area (Pavlides, 1968, p. 12-13).
Folding took place during the Taconic orogeny in a large
area north and west of the thesis area.
Intense folding in
the Rimouski-Matapedia region some sixty miles north and
northwest of the thesis area at least locally predated the
Early Llandovery (Lajoie and others, 1968, p. 21).
An angular
unconformity at Ashland, forty miles to the southwest of the
thesis area, was produced by folding and erosion some time
between the Middle Ordovician and the Late Llandovery
(Mencher and others, unpublished information).
Relationships between these two regions are less well
known.
A probable disconformity separates Late Ordovician
and Late Llandovery beds about thirty-five miles south of the
thesis area (Boucot and others, 1964, p. 91).
Near Stockholm,
fifteen miles southwest of the thesis area, Laux and Warner
(1966, p. 16) report a possibly conformable contact between
Late Ordovician and Llandovery beds.
In the thesis area, no unconformity of regional
significance occurs between the Middle Ordovician and the
Late Silurian.
However, detailed sedimentological analysis
has shown that tectonic activity may have occurred in the
thesis area in the early Early Llandovery (p. 112).
Any
possible folding at that time would be characterized by
disharmonic relationships with undeformed beds.
Such a
process is occurring today in the Caspian Sea (Neprochnov,
1968, p. 1038).
118
FIELD ANALYSIS
Macroscopic Features
The structural data and a geological map of the thesis
area are presented in Figures 48 and 49.
The dominant
structural feature is an apparently homogeneous system of
tightly appressed symmetrical folds.
These folds are
probably similar and may be plane and cylindrical, although
the map does not indicate whether or not some of the fold
elements may be curvilinear.
absent.
Large-scale faulting is
Small-scale faults are abundant but are poorly
defined.
A cross-section showing the style of folding is given
in Figure 38 (p. 119).
The TH165 section is one of the
two well-exposed areas of fold closure in the thesis area.
The folds are open and
asymmetric, which is unusual for
the thesis area as a whole.
More typical folding is
illustrated in Figure 39 (p. 120).
The section lines on
which Figures 38 and 39 are based are given in Figure 49.
The section as a whole faces upwards to the northeast.
However, between TH215 and DR1065 the beds are reversed.
The zones of fold closure in this section must be on the
order of one hundred feet across.
The narrow zones of
closure and the isoclinal nature of folding are typical of
the thesis area as a whole, which suggests that folding
in the thesis area is generally similar.
118
FIELD ANALYSIS
Macroscopic Features
The structural data and a geological map of the thesis
area are presented in Figures 48 and 49.
The dominant
structural feature is an apparently homogeneous system of
tightly appressed symmetrical folds.
These folds are
probably similar and may be plane and cylindrical, although
the map does not indicate whether or not some of the fold
elements may be curvilinear.
absent.
Large-scale faulting is
Small-scale faults are abundant but are poorly
defined.
A cross-section showing the style of folding is given
in Figure 38 (p. 119).
The TH165 section is one of the
two well-exposed areas of fold closure in the thesis area.
The folds are open and
asymmetric, which is unusual for
the thesis area as a whole.
More typical folding is
illustrated in Figure 39 (p. 120).
The section lines on
which Figures 38 and 39 are based are given in Figure 49.
The section as a whole faces upwards to the northeast.
However, between TH215 and DR1065 the beds are reversed.
The zones of fold closure in this section must be on the
order of one hundred feet across.
The narrow zones of
closure and the isoclinal nature of folding are typical of
the thesis area as a whole, which suggests that folding
in the thesis area is generally similar.
FIGURE 39
STRUCTURAL CROSS-SECTION
AT THE DR1065 SECT/ON
CARYS
200
FORMATION
MILLS
MIDDLE SLATE
fMEMBER~
FEETO
LOWER L IMESTONE
MEMBER!
C-
D
/00/
200
((
300
160
260
360
400
560
1000
FEET
V
BEDDING READING
C
NORTHWEST
~~
BEDDING AND FACING READINGS
(BEDS OVERTURNED)
D
SOUTHEAST
rf
121
Mesoscopic' Features
Most of the outcrops of the thesis area are not large
enough to provide any information on structures with a scale
of tens of feet.
Large exposures such as B4558 and DR1065
which are located on the limbs of macroscopic folds show no
mesoscopic features and are perfectly regular in their structure.
One large outcrop, Ez557, occurs at the closure of a
major fold.
(See Figure 49.)
The beds exposed at a4557
are the upper 170 feet of the Siegas Formation.
The beds
are well exposed in a continuous outcrop on both sides of
a road cut. Detailed structural and stratigraphic
correlations across the road led to the structural map
presented in Figure 40 (p. 122).
The striking feature of
this map is the non-plane, non-cylindrical style of folding.
The contrast to the style of folding of the thesis area as a
whole (Figure 49) suggests that nonplane, noncylindrical
folding in the thesis area is restricted to the mesoscopic
scale in zones of macroscopic fold closure.
STEREOGRAPHIC ANALYSIS
Procedure
The method of stereographic analysis used was that of
Turner and Weiss (1963) with one important modification.
No attempt was made to divide the thesis area into spatial
35
BEDDING
READING
WITH
DIRECTION
AND MAGNITUDE
FEET
40
6O
80
80
So
OF DIP
123
domains, but the stratigraphy of the thesis was used to define
temporal domains.
This procedure was used by Hall (1964,
p. 112) to distinguish between Acadian and Taconic folds
in the Spider Lake area.
A valid structural domain is defined with respect to
penetrative
a particular fabric element where the element is
on the scale of the domain.
The only fabric elements known
to be related to folding in the thesis area are bedding
and cleavage.
Bedding is
possible domains.
penetrative with respect to all
Cleavage, however, is
penetrative only
in the lower member of the Perham Formation, the middle slate
member of the Carys Mills Formation, and the Madawaska Lake
Formation.
The middle slate member of the Carys Mills Formation
did not provide sufficient data for analysis.
Various domains were defined and the poles of the
relevant fabric elements were plotted on an equatorial,
20-cm, Schmidt net.
as N.
The number of poles plotted is denoted
The distribution of points was then contoured by the
Free-Counter method (Turner and Weiss,
1963, p.
61).
Great
circles Ai which are trends of possible structural
significance were fitted to the maxima of the resultant
diagrams.
The great circle representing the most
conspicuous maximum was studied to locate the minimum of the
data distribution within the great circle.
The pole of this
great circle was taken to be the "fold axis" a.
The pole and
the associated minimum defined the "axial plane" P of folding
in the domain.
The significance of these fold elements
124
depends on the nature of folding in each domain.
Maxima defined by circumferential elongations of the
data distributions near the margins of the diagrams are due
simply to the properties of the Schmidt net (Vistelius, 1966,
p. 10).
Bedding
The thesis area domain includes bedding readings from
all stratigraphic units in the thesis area.
The structural
diagram for this domain is presented in Figure 41 (p. 125).
The distribution is interpreted (Turner and Weiss, 1963,
p. 44, p. 76, p. 159) as representing a system of grossly
homogeneous, tightly appressed, plane, symmetrical, similar
folds.
This conclusion is consistent with the findings
of the field analysis.
However, the apparently noncylindrical
nature of the fold system and the
asymmetric distribution
of data suggests that internal heterogeneities are present
in the domain.
The Silurian domain (Figure 42, p. 126) contains all
bedding readings from the Perham and the Siegas Formations
within the thesis area.
The fold system is homogeneous,
plane, cylindrical, tightly appressed, similar, and has
orthorhombic symmetry.
The axial plane of the system is
N43E87N and the axis strikes S43W plunging 2 degrees.
The Ordovician domain (Figure 43, p. 127) consists of
all bedding readings from the Carys Mills and Madawaska Lake
125
FIGURE 4 /
DISTRIBUTION
BEDDING POLES OF THE
THESIS AREA DOMAIN
OF
contoured in points per 1 percent area
N = 360
Al = N50W85N
A2 = N50W64N
A3 = N62W80N
a = S41W5 0
P = N40E88S
..TM
126
FIGURE 42
DISTRIBUTION
BEDDING POLES OF THE
SILURIAN DOMAIN
OF
contoured in points per 1 percent area
N= 225
A, = N42W50S
A 2 = N47W70S
A 3 = N47W88N
a = S43W20
P = N43E87N
ru-C
127
FIGURE 43
DISTRIBUTION
BEDDING POLES OF THE
ORDOVICIAN DOMAIN
N
contoured in points per 1 percent area
N = 230
A, = N40W70N
A 2 = N4OW50S
A3
=
N50W74N
A 4 = N59W80N
a = S41W16 0
P = N33E69N
OF
128
Formations in the thesis area.
The conspicuous noncylindrical
aspect of the data suggests the Possibility of internal
heterogeneity.
The Carys Mills domain (Figure 44, p. 129) contains all
bedding readings from the Carys Mills Formation in the thesis
area.
The fold system of this domain is apparently
cylindrical which indicates that deformation of the Carys
Mills Formation was fundamentally identical to that of the
Silurian domain.
However, the "fold elements" here have
values intermediate between those of the Silurian and the
Ordovician domains which suggests that the possibility of
internal heterogeneity cannot be dismissed.
The abundance
of data does not permit further subdivision of the domain.
The Madawaska Lake domain (Figure 45, p. 130) consists
of all bedding readings from the Madawaska Lake Formation.
The folds of this domain are plane, noncylindrical, tightly
appressed, similar, inclined and
asymmetric.
The "fold
axis" has no real meaning since axes are evidently curvilinear.
The "axial plane" may not have significance since the
possibility of internal heterogeneity cannot be dismissed.
The data do
not permit further subdivision of the domain.
The heterogeneity of the thesis area and the Ordovician
domains is
concentrated in the Madawaska Lake domain.
A
significant structural contrast separates the Madawaska Lake
Formation from younger rocks of the thesis area.
The
intermediate features of the Carys Mills domain suggest that
this contrast is expressed not by some discontinuity but by
129
FIGURE 44
DISTRIBUTION
BEDDING POLES OF THE
CARYS MILLS DOMAIN
OF
contoured in points per 1 percent area
N= 135
A1 = N42W84N
A 2 = N46W87N
A 3 = N53W74S
a = S44W8 0
P = N41E72N
Tfts
130
FIGURE 45 DISTRIBUTION OF
BEDDING POLES OF THE
MADAWASKA LAKE DOMAIN
contoured in points per 1 percent area
N =93
A1 = N28W68N
A 2 = N43W44N
A 3 = N43W57N
A 4 = N43W70N
a = S48W33 0
P = N22E56N
T/1S
131
a disharmonic regioninvolving the older beds of the Carys
Mills Formation.
Cleavage
The Lower Perham domain (Figure 46, p. 132) consists of
all cleavage readings from the lower member of the Perham
Formation in the thesis area.
homogeneous.
The data distribution is quite
Cleavage is distributed symmetrically with
respect to fold elements.
The "fold axis" of the domain is
unlike any found previously and is of unknown significance.
The axial plane is most similar to that found for bedding in
the Silurian domain (p. 126).
The Madawaska Lake domain (Figure 47, p.-133) contains
all cleavage readings from the Madawaska Lake Formation in
the thesis area.
The distribution is homogeneous and suggests
that the associated folds are plane and not inclined.
The
"fold axis" is again of unknown significance but is very
similar to that of the Lower Perham domain.
The axial plane
is identical to that found for bedding in the Silurian domain
(p. 126).
All cleavage in the thesis area was produced by the
process that generated the folds of the Silurian domain.
No
cleavage anomaly is associated with the anomalous style of
folding of the Madawaska Lake domain.
132
DISTRIBUTION
FIGURE 46
CLEAVAGE POLES OF THE
LOWER PERHAM DOMAIN
N
contoured in points per 1 percent area
N = 63
A, = N9W70S
A 2 = N42W79S
a = N48E13 0
P = N51E77N
OF
133
FIGURE 4/7
DISTRIBUTION OF
CLEAVAGE POLES OF THE
MADAWASKA LAKE DOMAIN
contoured in points per 1 percent area
N = 78
Al = N46W50N
A 2 = N49W80S
a = N39E10 0
P = N42E80N
1-r"~
134
TECTONIC INTERPRETATION
Acadian Orogeny
Silurian rocks were deformed by a homogeneous system
of plane, cylindrical, tightly appressed, similar folds
which is slightly inclined and plunging.
The similarity of
these features to those of the thesis area as a whole shows
that the bulk deformation of the thesis area post-dated the
Early Ludlow (p. 29).
The regional interpretation indicates
that this deformation was due to the Acadian orogeny.
The
inclination and plunge of the Acadian fold system are
probably related to the morphology of the Pennington anticlinorium (p. 16).
The slight plunge of the fold system
explains the abundance of Ordovician rocks in the northeast
part of the thesis area.
(See Figure 49.)
The Acadian orogeny
also produced a homogeneous cleavage system in the thesis area
symmetrically dispersed to the axial plane of folding.
Heterogeneity of Acadian fold elements was restricted to the
mesoscopic scale on zones of macroscopic fold closure (p. 121 ).
The Acadian fold system has orthorhomnbic symmetry with an
axis of S43W plunging 2 degrees and an axial plane of N43E87N.
The three symmetry axes are the axes of the pure-strain
ellipsoid (Turner and Weiss, 1963, p. 520).
It is probable that
the axis normal to the axial plane is the direction of maximum
pure strain.
These conclusions are valid on the scale of the
thesis area.
Larger scale considerations must take into
135
account rotational and translational strain components
introduced by the development of structures such as the
Pennington anticlinorium.
Laboratory and field investigations of fabric elements
suggest that bedding in most of the upper member of the Perham
Formation, most of the Siegas Formation, and a large part of
the Carys Mills Formation was kinematically active.
The
mechanism of folding of the upper member of the Perham Formation
and the Siegas Formation was mainly flexural-slip.
Cleavage
was an active fabric element in the Madawaska Lake Formation,
the lower member of the Perham Formation, and a large part of
the Carys Mills Formation.
The mechanism of folding of the
Madawaska Lake Formation and the lower member of the Perham
Formation was mainly slip or shear folding.
The mechanism of
bulk deformation of the Carys Mills Formation is not known.
Knowledge of the symmetry and mechanism of folding of the
upper member of the Perham Formation and the Siegas Formation
makes it possible to "unfold" beds of these formations (Turner
and Weiss, 1963, p. 516-518).
This is not possible for the
Madawaska Lake Formation and the lower member of the Perham
Formation.
Lack of knowledge of the mechanism of bulk
deformation and the depth of folding in the thesis area makes
the construction of palinspastic maps impossible.
Older Structures
A significant contrast in the style of folding between
136
the Madawaska Lake Formation and younger units is probably
marked by a structural disharmony involving beds of the lower
part of the Carys Mills Formation (p.128 ).
The structure of
the Madawaska Lake Formation can be regarded as a composite of
structures produced by homogeneous strain of Acadian folding
and other structures.
These other structures must be either
pre-Acadian or due to local stress-perturbation within the
Madawaska Lake Formation by lithologic heterogeneity across
the thesis area (p. 21).
If the latter is the case, then it
is difficult to explain why no such heterogeneity of
structure occurs in the Siegas Formation which also is quite
variable (p. 89).
It is also hard to explain why cleavage
distributions in the Madawaska Lake Formation were not
affected by local stress-perturbation.
The anomalous
structures of the Madawaska Lake Formation in the thesis area
are probably partly pre-Acadian.
These older structures were most probably folds but are
difficult to discuss in more detail.
Since folding is a
process that takes place at depth, the structures can only be
dated between the Middle Ordovician and Middle Devonian.
Both the Taconic orogeny and the Salinic disturbance (Boucot,
1968, p. 86) occurred in this time interval.
Since pre-Acadian
deformation in the Madawaska Lake Formation was not of high
enough intensity to produce cleavage (p. 131) it is possible
that the folding was associated with the Salinic disturbance.
However, it is the writer's judgment that the pre-Acadian
structures of the Madawaska Lake Formation were produced by
137
low-intensity folding accompanying the development of shelf
margins in the thesis area during the early or middle Early
Llandovery (p. 112).
During the Taconic orogeny the thesis area was
characterized by continuous sedimentation and simultaneous
folding at a depth greater than about 1300 feet.
The thesis
area must be located in the "belt of conformity" of Pavlides
and others (1968, p. 62) although the effects of nearby
disturbances exist.
The beginning of the Taconic orogeny
to the north of the thesis area may be tentatively dated by
the occurrence of the first exogenic event of the Siegas
Formation (p.
82) as early Early Llandovery.
This is older
than the late Early Llandovery age found in the Presque Isle
area by Pavlides (1968, p. 38) but is younger than the preEarly Llandovery age found for the Temiscouata area (Lajoie
and others, 1968, p. 638) which suggests a complicated
history of regional tectonic activity.
138
ASPECTS OF THE REGIONAL GEOLOGY
SUA4ARY
The thesis area is critical in the evaluation of
regional stratigraphy during the middle to late Ordovician
and the early Silurian since for the first
time rocks of
the western clastic facies are observed in direct contact
with limestones of the Carys Mills Formation.
Paleontological
and thickness information suggests that the Madawaska Lake
Formation and the Carys Mills Formation are laterally
equivalent in the range Zone 13 through the Late Ordovician
and that the facies boundary is transgressive to the northwest.
Sedimentological information and age relationships
suggest that the Siegas Formation is laterally equivalent
to Early Llandovery beds of the Carys Mills Formation in the
Aroostook-Matapedia anticlinorium.
be regarded in
The Siegas Formation may
a regional sense as a marginal clastic facies
of the Carys Mills Formation.
Further work is needed to
define the relationship of the Siegas Formation to the
Frenchville Formation.
The nature of the sedimentation of the Carys Mills
Formation in the Aroostook-Matapedia belt is examined in
relation to the Black Sea model developed for the thesis
area.
Recent suggestions that the Carys Mills Formation
is a calcareous flysch or some sort of shallow-water shelf
deposit are not supported by the available lithologic and
139
faunal evidence.
The Black Sea model of accumulation
beneath stagnant bottom waters.of skeletal carbonate debris
produced by microbiotic activity in aerated surface waters is
successfully applied to the Carys Mills Formation on a
regional scale.
A mechanism for stagnation of bottom waters
is suggested by the partially land-locked nature of the
Aroostook-M1atapedia belt throughout most of its existence.
The tectonic stability of the Aroostook-Matapedia belt
through the Taconic orogeny is similar to the tectonic
stability and continuous sedimentation of the Black Sea
through the major events of the Alpine otogeny.
Methods of directly testing the validity of the Black
Sea model are proposed, including organic carbon analysis,
electron microscopy of limestones,
and field work near the
margins of the Aroostook-Matapedia belt.
Paleogeographic analysis of the region in the Early
Llandovery shows that the source area of the Siegas Formation
was located in a relatively small region in northwest New
Brunswick now covered by Devonian rocks.
The effects of the
Taconic orogeny in northeastern Maine suggests that the
Taconic orogeny was characterized by the uplift of discrete,
relatively isolated anticlinoria mantled by Iiddle Ordovician
mafic volcanic rocks.
The source region of the Siegas
Formation was probably a discrete uplift in northwestern
New Brunswick similar to the Weeksboro-Lunksoos Lake
anticlinorium.
The source of the lithic wacke facies of the
Siegas Formation was mafic volcanic rocks of either Middle
140
Ordovician or early Silurian age.
The source of the arkosic
and orthoquartzitic facies of the Siegas Formation consisted
of rocks similar to the Rockabema Quartz Diorite and either
quartz arenites related to the Grand Pitch Formation or quartz
arenites of the Quebec Group.
REGIONAL STRATIGRAPHY
In northeastern Maine,
facies relationships in the
Middle and Late Ordovician and the early Silurian existed
between noncalcareous clastic rocks to the west and limestones
of the Carys Mills Formation to the east (Pavlides and others,
1964, p. C31-C32).
The facies boundary defines the western
margin of the Arookstook-Matapedia
Boucot, 1968, p. 36-37).
belt (Berry, 1968, p.
In the thesis area,
28-31;
rocks from the
two facies are observed in contact for the first time.
General relations of the Madawaska Lake Formation to the
Carys Mills Formation have suggested that the two formations
are partial lateral equivalents.
The age of the Madawaska
Lake Formation ranges between Zone 12 of the Caradoc and
the latest Ordovician (Mencher and others, unpublished
information; Laux and Warner, 1966, p. 11).
The age of the
Carys Mills Formation ranges between Zone 13 of the Caradoc
and Zone 19 of the Llandovery (Pavlides, 1968, p. 10).
The
Carys Mills Formation underlies Silurian rocks on the east
flank of the Stockholm Mountain synclinorium and the
Madawaska Lake Formation underlies Silurian rocks on the west
141
flank.
In the thesis area the Madawaska Lake Formation
conformably underlies the Carys Mills Formation (p. 36).
The age of the top of the Madawaska Lake Formation decreases
from latest Ordovician near Stockholm (Laux and Warner, 1966,
p. 11) to latest Middle Ordovician in the thesis area (p. 37)
to pre-Zone 13 (if present) northwest of Caribou (Pavlides,
1968, p. 12).
The thickness of the Carys Mills Formation
decreases from about 9000 feet in the Presque Isle area
(Pavlides, 1968, p. 10) to 1300 feet in the thesis area
The Madawaska Lake Formation and the Carys Mills
(p. 32).
Formation are laterally equivalent at least in the range
Zone 13 through the Ordovician.
The facies boundary is
trangressive to the northwest.
It
is
possible to relate the Siegas Formation on a
regional scale to the Carys Mills Formation.
The age range
of the Carys Mills Formation in the Aroostook-Matapedia
anticlinorium includes the Early Llandovery.
In the thesis
area the age of the top of the Carys Mills Formation is
earliest Silurian (p. 32).
However, the age of the top of
the Siegas Formation is Early Llandovery (p. 61) and the in
situ sedimentation characteristic of the formation has been
shown to be essentially a continuation of the depositional
environment of the Carys Mills Formation (p. 82).
The exogenic
deposits of the Siegas Formation are local in extent (t.
59)
and were transported from the north towards the AroostookMatapedia belt (p.
107).
The Siegas Formation is
laterally
142
equivalent to Early Llandovery beds of the Carys Mills
Formation in the Aroostook-Matapedia anticlinorium and can
be considered on a regional scale to be a marginal clastic
facies of the Carys Mills Formation.
The relationship of the Siegas Formation to the
Frenchville Formation (Boucot and others, 1964, p. 31)
remains to be established by further work.
The Frenchville
Formation is absent in the thesis area and is thought to
interfinger with the lower member of the Perham Formation
between Stockholm and the thesis area (Roy, 1967, unpublished
map).
The Frenchville Formation is composed in part of quartz
arenites and lithic arenites similar to rocks of the Siegas
Formation (Laux and Warner,
1966,
p. 11).
All fossil ages
of the Frenchville Formation are Late Llandovery to early
Wenlock (Boucot, 1968, p. 84-85).
(1966,
However, Laux and Warner
p. 16-17) suggest that the basal beds of the Frenchville
Formation near Stockholm may be as old as earliest Silurian.
Consequently it is possible that parts of the Frenchville
Formation may be laterally equivalent to the Siegas Formation.
SEDIMENTATION IN THE AROOSTOOK-MATAPEDIA BELT
The Aroostook-Matapedia belt was a persistent and welldefined geographical feature from Zone 12 of the Caradoc
(Berry, 1968, p. 28) to the Late Llandovery (Boucot, 1968,
p. 87).
The belt was the site of continuous accumulation of
at least 3 miles of sediment of which the bulk is included in
143
the Carys Mills Formation of Zone 13 to Zone 19 age (Pavlides,
1968, p. 10).
The belt was tectonically stable through the
Taconic orogeny which severely deformed both of its margins
(Pavlides and others,
1968, p. 62).
The sedimentation of the Carys Mills Formation is not
well understood.
Recent studies have considered the formation
to be a "calcareous flysch" (Boucot, 1968, p. 87) or some sort
of shallow-water platform deposit (Neuman, 1968, p. 46).
Although some features of turbidite deposition occur in the
formation (Pavlides, 1963, p. 9) the scarcity of the features
suggests that turbidity flow cannot account for the deposition
of most of the beds (p. 48).
Between the Washburn area and
the thesis area the only common sedimentary structure is crosslamination modified by convolute lamination and most of the
beds are completely unstructured (Hamilton-Smith, 1966,
unpublished information).
The evidence suggests that the
Carys Mills Formation cannot be characterized as a calcareous
flysch.
Deposition of the formation probably did not take place
in a shallow-water environment.
The complete absence of
typically shallow-water sedimentary structures, the striking
lithological uniformity, and the complete absence of benthonic
faunal remains (except transported assemblages) indicates an
environment unlike any shallow-water region of carbonate
deposition observed today.
The characteristics of the Carys EKills Formation in the
Aroostook-Matapedia belt are very similar to those in the
144
southern part of the thesis area.
The Black Sea model of
sedimentation which was successfully applied in the thesis
area (p. 51) is essentially the accumulation beneath stagnant
bottom waters of skeletal carbonate debris produced by
microbiotic activity in aerated surface waters.
The application
of this model to the sedimentation in the Aroostook-Matapedia
belt is consistent with what is known of the lithology and
fauna of the Carys Mills Formation.
On the regional scale,
two other characteristics of the Carys Mills Formation can
be explained with the Black Sea model.
Stagnation of bottom
waters requires a basin with restricted circulation.
Paleogeographic and facies reconstructions (Berry, 1968, p. 31;
Boucot, 1968, p. 86) suggest that the Aroostook-Matapedia belt
was partially land-locked throughout most of its existence.
The tectonic stability of the Aroostook-Matapedia belt has
been mentioned.
The deep basin of the Black Sea is a
sedimentary environment where deposition has taken place
steadily since the Paleozoic, undisturbed by the major events
of the Alpine orogeny (Milanovskiy, 1968, p. 1241).
The Black Sea model is attractive in that it accounts
for most features of the Carys Mills Formation in the
Aroostook-Matapedia belt.
However, direct evidence
substantiating the model is largely lacking.
The proposed
environment should be characterized by high concentrations
of organic carbon that could be easily described by standard
analytical techniques.
Although recrystallization has largely
formed the fabric of the limestones of the Carys Mills Formation,
145
electron microscopy (i.e., Fischer and others, 1967) should
find evidence of the original micro-skeletal origin of the
carbonate sediment.
The significant lateral variations within
the Carys Mills Formation of the thesis area suggest that
normal field techniques would be most informatively applied
near the margins of the Aroostook-Matapedia belt.
PROVENANCE OF THE SIEGAS FORMATION
Sedimentological analysis of the exogenic component of
the Siegas Formation shows that two possibly associated sources
can account for all of the coarse clastic material involved in
exogenic sedimentation (p. 82).
The first source was made up
of mafic volcanic rocks, mainly andesites, and cherts.
The
second source was made up of quartz arenites and salic plutonic
rocks with a composition between diorite and granite.
This material was transported into the thesis area from
the north (p. 111).
The transport of coarse-grained material
into the thesis area suggests that the head of the submarine
canyon was near shore (Hand and Bnery, 1964, p. 540) and
suggests that the source areas were at least within tens of
miles of the thesis area.
Paleogeographical and facies analysis of the Early
Llandovery rocks of the Cabano Formation in the RimouskiTemiscouata area (Lajoie and others, 1968,-p. 625-626) indicates
the presence of a minor source of mafic volcanic rocks to the
southeast.
The presence of Early Llandovery fossils in
146
limestones of the Carys Mills Formation near Leclerc in
northern New Brunswick (Ayrton and others, 1969, p. 475)
restricts the possible location of the source area of the
Siegas Formation to western Restigouche County- or central
Madawaska County in New Brunswick.
These areas are now
covered mainly by Devonian rocks (Potter and others, 1968).
The source area of the Siegas Formation cannot be more than
sixty miles away from the thesis area and is probably no more
than thirty miles distant.
The Weeksboro-Lunksoos Lake anticlinorium (Figure 2,
p. 16) is cored by quartz arenites and slates of the Grand
Pitch Formation of Cambrian (?) age and mantled by Middle
Ordovician mafic volcanic rocks and chert (Neuman, 1967,
p. 15-112).
This complex was intruded by the Rockabema Quartz
Diorite during the Middle or Late Ordovician (Ekre:!n and
Frischkheckt, 1967, p. 8-11).
The anticlinorium was deformed
by the Acadian orogeny but was originally uplifted during the
Taconic orogeny (Neuman, 1967, p. 132).
The Munsungun Lake
anticlinorium (Hall, 1964, p. 7) is cored by Cambrian (?)
slate of the Chase Brook Formation and is mantled by Middle
Ordovician volcanic and sedimentary rocks.
This anticlinorium
was also originally uplifted during the Taconic orogeny
(Hall, 1964, p. 127).
The mass of Middle Ordovician mafic
volcanic rocks between Presque Isle and Ashland (Unit Ovs of
Boucot and others (1964, p. 17)) may have been uplifted during
the Taconic orogeny, as suggested by paleocurrent and facies
analysis (Mencher and others, unpublished information).
147
Deformation in northeastern Maine during the Taconic orogeny
was characterized by the development of discrete, relatively
separate anticlinoria.
The uplifts described account for all
but one of the unconformities in the area summarized by
Pavlides and others (1968, p. 62).
It is suggested that the source area of the Siegas
Formation was a Taconic anticlinorial uplift much like the
ancestral Weeksboro-Lunksoos Lake anticlinorium.
The
structure was cored by either lithologic equivalents of the
Grand Pitch Formation or by similar rocks of the Quebec Group
(Lesperance,
1959,
p. 4-5).
The structure was mantled either
by Middle Ordovician mafic volcanic rocks or by syntectonic
early Silurian volcanic rocks (Lajoie and others, 1968, p. 627).
The complex was probably intruded by late Ordovician salic
plutonic rocks similar to the Rockabema Quartz Diorite.
Such
a source would have provided all the exogenic components of
the Siegas Formation.
The history of the source area was evidently complicated.
The detrital products of the source area reached the thesis
area in the Early Llandovery but were most conspicuous in the
Rimouski-Temiscouata area in the Late Llandovery (Lajoie and
others, 1963, p. 639).
these differences.
Further work is needed to explain
148
APPENDIX 1
SUMMARY OF PALEONTOLOGICAL INFORMATION
CARYS MILLS FORMATION
E4661
Stratigraphic Assignment
EM4661 is
assigned to the base of the upper limestone
member of the Carys Mills Formation, about 300 feet
below the top of the formation.
Location
a) 1.50 miles S7.5E of (470151. 68000')
b) 4.03 miles S68W of (47015,, 670551)
c) 4.27 miles N3E of (470103, 68000,)
The outcrop is a shallow road cut on both sides of a
farm road.
Lithology
Dark gray, fine-grained, thinly bedded limestone.
Typical lithology of the Carys Mills Formation.
Fossil Listing
Climacograptus, possibly scalaris
Krausella
sp.
Schmidtella ?
sp.
smooth ostracodes, indet.
149
Age
Dr. Jean M. Berdan reports on the ostracodes in
a letter of October 10, 1968,
"This collection is
probably Ordovician rather than Silurian in age
but cannot be dated precisely."
Dr. William B.N.
Berry reports on the graptolite in a letter of
March 26, 1968,
"I would suggest that the beds
were within a Late Ordovician-Early Silurian
(Llandovery) age span anyway and thus lean a
little toward the Silurian age."
EX1154
Stratigraphic Assignment
EX1154 exposes the contact of the Carys Mills Formation
and the Siegas Formation and the upper 100 feet of the
Carys Mills Formation.
The collections were made
about 50 feet below the top of the formation in the
upper limestone member of the Carys Mills Formation.
Location
a) 5.10 miles N83.5E of (470151, 68000')
b) 1.28 miles N63E of (47'15', 670551)
c) 7.28 miles S45E of (470151, 68000,)
The outcrop is
a large road cut on the south side
of the main road.
150
I
Lithology
Medium gray, fine-grained, very thinly bedded
limestone.
Fossil Listing
Aechmina
Tricornina
sp.
sp.
Grammolomatella
?
sp.
paleocopid and beecherellid ostracodes, indet.
Dr. Jean M. Berdan reports, in a letter of October 10,
1968, that "the ostracodes could be anything from Late
Ordovician to Early Devonian in age."
However, detailed
stratigraphic correlations conclusively indicate that
the collections at E11154 were taken from the same
stratigraphic interval (t 30 feet) at TH165.
of the collection from TH165 is
discussed in
The age
detail
(P.153).
TH308
Stratigraohic Assignment
TH308 is assigned to the upper limestone member of the
Carys Mills Formation.
Dr. Jean M. Berdan reports,
in a letter of October 10, 1968, that "Ei1154 and TH308
probably represent the same horizon, as in addition to
the ostracodes mentioned above, they have other
151
undescribed species in common."
On this basis the
stratigraphic assignment may be refined.
TH308
probably occurs about 50 feet below the top of the
Carys Mills Formation.
Location
a) 4.76 miles N86.5E of (470151, 680001)
b) 0.88 miles N68E of (47015,, 67 55')
c) 7.23 miles S41E of (470201, 68 000,)
The
outcrop is a very small exposure in a small
drainage in the woods on the north side of the main
road.
Lithology
Medium gray, fine-grained, very thinly bedded limestone.
Fossil Listing
Aechmina
sp.
Tricornina
Aechminaria
sp.
sp.
paleocopid and beecherellid ostracodes, indet.
Dr. Jean M. Berdan reports, in a letter of October 10,
1968, that "the ostracodes could be anything from Late
Ordovician to Early Devonian in age."
However, on the
basis of detailed stratigraphic and faunal correlations
it is clear that TH308 represents the same stratigraphic
horizon as EM1154 and TH165.
The age of the collection
152
at TH165 will be discussed in detail (p.15 3 ).
TH165
Stratigraphic Assignment
TH165 exposes the contact of the Carys Hills Formation
with the Siegas Formation and the upper 80 feet of the
Carys Mills Formation.
The collections were taken
from beds about 50 feet below the top of the formation,
in the upper limestone member of the Carys Mills
Formation.
The stratigraphic succession at TH165 is
identical to that at EM1154.
Location
a) 4.62 miles N87E (470151,
68000')
b) 0,75 miles N70.5E (470151, 67055,)
0
c) 7.16 miles S39.5E (47020', 68 00')
The outcrop is a large exposure in a road cut on the
south side of the railway.
Lithology
Medium gray, fine-grained,
very thinly bedded limestone.
Fossil Listing
Aechmina
Berounella
sp.
sp.
paleocopid and podocopid ostracodes, indet.
153
Dr. Jean M. Berdan reports in a letter of October 10,
1968 that "With the exception of the specimens of
Berounella, the ostracodes could be anything from
Late Ordovician to Early Devonian in age ...
the
presence of Berounella and the general aspect of the
fauna suggests an Early Devonian or latest Silurian
age."
Discussion
The age suggested by the age of the collection at TH165
is in striking contradiction to both the stratigraphy
of the thesis area and the age of the Carys Mills
Formation.
In a letter of October 10, 1968, Dr. Berdan
states the problem:
"With the exception of the specimens of
Berounella,
the ostracodes could be anything
from Late Ordovician to Early Devonian in
age.
However, according to Louis Pavlides,
the Carys Mills Formation has been dated
as not younger than Llandovery (Early
Silurian) on the basis of graptolites.
Although the presence of Berounella and the
general aspect of the fauna suggests an
Early Devonian or latest Silurian age, the
genus is rare and consequently not well
known and it is possible that it could occur
154
in older rocks.
Unless additional
evidence for a later age turns up from
other groups of fossils it seems better
to assume that the range of Berounella
extends downward rather than to revise
the age of the Carys Mills upward."
No other paleontological information in the thesis
area provides an independent estimate of the age of
the beds at TH165.
Assignment of TH165, EM1154
and TH308 to the
upper member of the Carys Mills Formation is based on
the lithologic similarity of the beds to the type
section at DR1066 and on the assignment of sandstone
beds at E41154 to the Siegas Formation.
Both of these
assignments are complicated by significant facies
changes in both the Siegas and the Carys Mills
Formations.
A more direct line of evidence is made
possible by the excellent structural control in the
TH165 region (p. 119).
TH165 must underlie TH288.
The beds at TH288 are mainly ferrous siliceous siltstone which is a characteristic minor lithology of
the lower member of the Perham Formation (p. 26).
The
lower member of the Perham Formation is pre-Ludlow in
age throughout its region of outcrop.
The beds at
TH165 are definitely pre-Ludlow in age and probably
pre-Silurian.
An extension of the age range of
Berounella is warranted.
155
SIEGAS FORMATION
EM558
Stratigraphic Assignment
EM558 is described earlier in the thesis (p. 61).
Collections in 1965 were made from beds in the upper
100 feet of the Siegas Formation.
Collections in 1967
were made from Bed 10, about 8 feet below the top of the
formation and Bed 16, about 23 feet below the top of the
formation.
Location
EMV558 is a large quarry located 1.1 miles N45E of Siegas,
New Brunswick.
All collections were made from beds
outcropping on the east wall of the quarry at the
uppermost level of excavation.
Lito
Bed 10 is a fine to coarse-grained, dark gray, graded
sandstone between 12 and 24 inches thick whose
sedimentary features suggest deposition by turbidity
currents.
The collection was made from the coarse-
grained material at the base of the bed.
Bed 16 is a pebble conglomerate whose clasts are
predominately limestone similar to that of the Carys
Mills Formation.
of Bed 10.
The matrix is similar to the sandstone
Samples were taken from the matrix near the
156
base of the bed where the concentration of clasts was
low.
Fossil Listn
a) 1965 Collection (Boucot, 1966, written communication)
Catazyga
sp.
7
sp.
7
Dalmanella
?
Eostropheodonta
Leangella
sp.
sp.
Mendacella
sp.
Eoplectodonta
sp.
Plectothyrella
Protatrypa
sp.
?
?
Skenidioides
Spirigerina
Stricklandia
sp.
7
sp.
sp.
sp.
dolerorthid
unidentified dalmanellid pedicle valves;
probably belonging to both Dalmanella
sp.
and Mendacella
unidentified brachiopods
Cornulites
sp.
tetracoral
favosited
heliolitid
halysitid
trilobite fragment
sp.
?
157
b) Bed 10 (USNM No. 17010)
(Boucot, 1968, written
communication)
dalmanellid
Lower Llandovery heliolitid (to Oliver)
c) Bed 16 (USNA No. 17012)
(Boucot, 1968, written
communication)
dalmanellid
Lower Llandovery heliolitid (to Oliver)
atrypacean
?
plectambonitid
coral
(to Oliver)
Age
In a recent review of the evidence, Ayrton and others
(1969, p. 470) state,
"Earlier unpublished fossil
reports by A.J. Boucot and R.B. Neuman (1965) pointed
to an early Llandovery age, which is confirmed by the
present restudy of the collection.
Critical to dating
the Siegas Quarry rocks is the presence of Stricklandia
which is unknown elsewhere in-the world below the base
of the Silurian.
Plectothvrella is known only from
beds of either Early Llandovery or Ashgill age.
Dalmanella
sensu strictu has not been confirmed above beds of
Early Llandovery age although it is abundant in the
later Ordovician;
Protatrypa,
above C
-
the same is
Eostropheodonta,
true for Catazyga.
and Mendacella are unknown
C2 of the Late Llandovery although, except
for Protatrypa, they can occur in the Ashgillian.0
158
It appears that the Siegas Quarry fauna can best
be interpreted to be of Early Llandovery age.
159
APPENDIX 2
METHOD OF INSOLUBLE RESIDUE ANALYSIS
SAMPLING AND PREPARATION
Unweathered hand samples of the limestones typical of the
Carys Mills Formation were collected from 21 outcrops of the
formation within the thesis area.
from TH408 and DR1065.
convenience.
Two samples were collected
Sampling was determined mainly by
In the laboratory an interior block was cut
from each hand sample to completely ensure the absence of
weathered material.
This interior block was then crushed to
coarse gravel size.
Approximately twenty to thirty grams of
this material were then washed, dried and accurately weighed.
Acid Digestion
The sample was initially immersed in approximately 100 ml.
of 2N acetic acid.
Reaction was initially vigorous but ceased
within a few hours due to the formation of an impermeable rind
of insoluble material around each of the sample grains.
This
rind was disaggregated by crushing the grains gently with a
rubber pestle within the polyethylene dishes where acid
digestion has taken place.
The mixture of used acid and
disaggregated insoluble residue was washed away from the
remaining limestone grains and temporarily set aside.
The
remaining limestone grains were immersed in about 100 ml. of
160
fresh acid.
This process was repeated as many times as necessary to
obtain complete disintegration of each sample.
Since the rate
of reaction with 2N acetic acid decreased significantly after
repeating the process a few times, 4N HC
was used as the
reagent in the final stages of digestion of each sample.
Samples of the insoluble residue were examined before and after
solution in HCl.
No obvious difference was noted.
All
insoluble residual material of each sample was finally
normalized with respect to solubility in 4N HCl.
At the level of acid strength used in this analysis,
solution of clay minerals is probable.
The extent of solution
of clay minerals is directly related to the time of solution.
To provide information bearing on this source of error, the
length of time of solution for each sample in both 2N acetic
acid and 4N hydrochloric acid is summarized below.
S
Length of Time of Solution (hours)
2N Acetic
4N HCl
% Insoluble
Residue
Total
TH1
165
71
236
7.5
TRi18
192
49
241
11.4
TH50
192
143
335
11.9
TH51
309
71
380
15.0
TH165
184
678
862
19.0
TH171
184
194
378
23.6
TH260
165
71
236
6.9
TH261
192
119
311
6.0
161
Sample
Length of Time of Solution (hours)
2N Acetic
4N HCl
% Insoluble
Residue
Total
TH264
311
71
382
10.8
TH308
169
736
905
25.7
TH360
171
27
198
23.5
TH386
170
26
196
21.7
TH408 1
170
26
196
23.3
TH4082
50
119
169
23.4
TH413
170
28
198
DR699
311
71
382
14.4
DR700
170
28
198
14.9
DR1065 1
169
209
378
23.4
DR10652
222
119
341
20.0
EM326
429
98
527
15.8
EM661
429
98
527
18.2
EM1154
184
812
996
22.8
EM1184
171
27
198
16.5
8.7
Examination of these figures shows that insoluble
residue content of the samples is independent of the length
of time of immersion in acid.
The variation in the length of
time of solution needed for disaggregation is probably related
in part to the nature of the carbonate minerals in the samples.
When the samples were completely disaggregated the
insoluble residue was separated from the acid in which it had
been suspended.
This separation was done by forced filtering
162
through a fine ceramic filter.
washed and again filtered.
three times.
The insoluble residue was
The. washing process was repeated
The remaining insoluble residue was thoroughly
dried and weighed.
If this weight is called W and the
C1
initial weight of the sample is W2 then the insoluble residue
content of the sample is simply:
I% =
W2
x
100
163
APPENDIX 3
VERTICAL VARIATION OF INSOLUBLE RESIDUE CONTENT
OF LIMESTONES OF THE CARYS MILLS FOR4ATION
INTRODUCTION
W.J. Wright (1945, unpublished map and tables) studied
the Carys Mills Formation in an area 2000 feet by 7300 feet
immediately to the west of EX558.
The work involved extensive
drilling, insoluble residue analysis of drill cores and the
preparation of a detailed (1 inch = 200 feet) geological map
of the area.
Zone 5 and 6 of Wright (1945) are equivalent to
the upper limestone member of the Carys Mills Formation.
Analyses of carbonate content of drill cores were made
throughout three complete sections through Zone 5 and Zone 6.
Since the purpose of Wright's study was to establish tonnage
and grade for mining prospects the samples analyzed were
probably bulk rock, including limestone, slate and shale (p. 39).
The individual results cannot be compared directly to the
insoluble residue values obtained in this thesis (p. 41).
For
the purposes of this thesis it is assumed that the nature of
the variation of carbonate content of the limestone lithotype
is
the same as the variation of bulk carbonate content in
the
three sections.
The unpublished work of Dr. Wright was made available to
the writer by R.R. Potter of the New Brunswick Department of
Natural Resources, Mineral Resources Branch.
164
ANALYSIS
Three cores were taken entirely through the upper limestone member of the Carys Mills Formation which led to the
definition of the local stratigraphy and carbonate content
at three sections to the west of EM558.
The data is summarized
in the accompanying graph.
1
---- -b
T413
Ir
n'tub e
44
3,
7
-
-
_~
_
~
Z
-
wd
1 hialo
disgancy in fee
-
e t
abi
-o
he
aseo
che
e
165
The drill hole 1-2 section occurs near EM661 where the upper
limestone member has a thickness of 141 feet.
The drill hole
4-5 section occurs near TH5 where the member is 173 feet thick.
The drill hole 6 section occurs near E4665 where the thickness
of the upper limestone member is 121 feet.
Evidently there is a systematic variation of bulk
insoluble residue content from the bottom to the top of the
member in all three sections.
The variation in thickness
between the members is evidently the result of truncation of
the top of the member either by faulting or erosion.
In view
of the lack of evidence for faulting and the abundant evidence
of erosion (p. 60, 66) the method of truncation is thought
to have been erosion.
VARIATION ANALYSIS
Let rn be an individual value of percent insoluble
residue.
of rn.
Let N be the total number of values in a given set
Then
1
a
4r
= -
NN
n
12
N
N
166
The results for the various sections are summarized below.
Drill Hole 1-2 Section
N
=
20
= 21.7%
= 21.65
=
4.7%
Drill Hole 4-5 Section
N = 24
a = 20.5%
s = 37.8
=
6.1%
Drill Hole 6 Section
N
=
a
= 22.4%
17
= 15.1
=
Then the average P is
3.9%
4.9%.
CONCLUSIONS
The vertical standard deviation of insoluble residue content
within the upper limestone member has been found to be about 5%.
It is assumed that this figure is applicable to the variation of
insoluble residue content in the limestones of the upper and
lower limestone members of the Carys Mills Formation.
The
167
standard deviation of insoluble residue content of limestones
of the Carys Mills Formation determined in this thesis is
6%,
which suggests that vertical variation is inadequate to account
for the insoluble residue variation within the thesis area.
168
APPENDIX 4
ANALYSIS OF CLASTS OF A CONGLOMERATE
BED OF THE SIEGAS FORMATION
INTRODUCTION
A portion of Bed 16 of E558 was chosen for detailed
An area 6 inches by 6 inches oriented
study in the field.
normal to bedding was chosen, and all the clasts within this
area were described.
The lithology, maximum and minimum
dimensions, and apparent angularity of each clast was
recorded.
This information led to the following analysis.
TERMS
1
average maximum dimension
w
average minimum dimension
r
1/w = sphericity
s
(1 + w)/2 = average size
lA .783 (1 x w) = average minimum area
2 (1 x w) = average maximum area
N a number of clasts counted
2N S .014N (a,+ a2) = concentration of clasts
in the bed
169
TOTAL ASSEMBLAGE
Total number of clasts in 36 inch square inches:
N
=
161
and for these clasts:
1
=
.37 inch
w
=
.23 inch
r
=
s
=
1.6
.30 inch
a=
.067 square inches
a2 =
.085 square inches
2 N=
.34
the composition of these clasts is:
limestone
67%
chert
15%
slate
8%
miscellaneous
1%
where the percentage is calculated
x%=
N
(100)
N
ANGULARITY
Considering the angularity of the various lithologies:
a)
limestone
angular
angalar-round
round
50%
35%
15%
170
b) chert
c) slate
d) all clasts
angular
12%
angular-round
25%
round
63%
angular
8%
angular-round
54%
round
38%
angular
40%
angular-round
35%
round
35%
GRAIN SIZE
Considering the size and sphericity of clasts of the
various lithologies:
a) limestone
1 =
.36 inch
w =
.23
inch
r = 1.6
b) chert
inch
S =
.30
1=
.30 inch
w =
.20
inch
r = 1.5
c) slate
S =
.25
inch
1 =
.63
inch
w =
.27
inch
r = 2.3
S =
.45
inch
171
APPENDIX 5
PETROGRAPHIC MODAL ANALYSIS OF SANDSTONES OF
THE SIEGAS FORMATION
METHOD OF ANALYSIS
Modal analyses of sandstones of the Siegas Formation
provide the basic evidence for facies variations in the
formation.
The samples examined were from graded sandstone
beds of EM558 (p. 69) and the thickly bedded sandstones of
the rest of the formation (p. 87).
Seventy-three samples
of these sandstones were collected from 27 outcrops
of the Siegas Formation.
medium-grained sandstone.
Each sample was unweathered
A thin section was cut
perpendicular to bedding in each sample.
These sections
were studied with the petrographic microscope without
universal stage or staining techniques.
Modal analyses
were based on the normal point counting technique using
300 points for almost every section.
The wide range of
sandstone compositions made fine discrimination between
similar values unnecessary which makes counting statistics
an insignificant source of error.
PETROGRAPHIC SPECIES
The following species were differentiated in the modal
172
analyses.
1. QUAR
- quartz
2. COM4Q
- composite quartz
3.
PLAG
- plagioclase feldspar
4.
KFEL
-
potassium feldspar
5.
PERT
-
perthite
6.
GRGR
-
graphic granite
7.
LITH
-
lithic fragments
a. MAVO
-
mafic volcanic rocks
b. SAPL
-
salic plutonic rocks
c.
LIME
-
limestone
d.
CHER
-
chert
- other lithic fragments
e. MISC
8.
ACCM
-
a.
PYRO
-
pyroxene
b.
MICA
-
mica
- other accessory minerals
c. MISC
9.
accessory minerals
MATR
-
matrix
Species 7e and 8c (MISC) were not differentiated in
actual analysis.
In samples where the additional information
would not have been useful, LITH and ACCM were not internally
differentiated.
Quartz (QUAR)
Quartz grains were of two types.
One was a medium- to
173
coarse-grained, rounded variety with undulose extinction
and strain lamellae.
The other type was fine to medium
grained, angular, and had no strain features.
Most
samples contained a mixture of these two types.
(See p. 103.)
Quartz of the sandstones of the orthoquartzitic facies was
often modified by the development of overgrowths.
Comoosite Quartz (CQ)
Composite quartz grains were aggregates of two or
more quartz crystals.
No particular number of crystals was
common and there was no preferred crystal orientation within
the composite grains.
Most crystal-crystal contacts are
planar, although concavo-convex and sutured contacts were
observed.
If the composite quartz grains were composed
of a very large number of small quartz crystals it was
impossible to distinguish the species from chert (CHER).
Plagioclase Feldspar (PLAG)
Plagioclase feldspar grains were of one type.
Albite twinning was common.
zoning were very scarce.
Other types of twinning and
Alteration of grains was minor
and most grains were perfectly clear.
All specifically
identified untwinned feldspar grains were orthoclase
feldspar (KFEL).
Untwinned plagioclase feldspar is not
174
present in the samples in significant quantities.
Specific determinations of the composition of the
plagioclase feldspar were made on 15 grains from Beds 8,
193, and 205 at EM558.
The compositions ranged from
An 2 6 to An4 5 and averaged An3 2 . The plagioclase feldspar
grains were very similar to the plagioclase feldspar
phenocrysts of the mafic volcanic fragments (MAVO).
Potassium Feldspar (KFEL)
Error in the identification of potassium feldspar may
be significant because staining techniques were not used.
Microcline twinning was scarce and the grains were generally
identified by cleavage and the degree of alteration, which
was moderate to extreme.
Almost all specific identifications
were of orthoclase feldspar.
Perthite (PERT)
This species included perthite and antiperthite and
intergrowths ranging in size from mesoperthite to cryptoperthite.
altered.
The grains were moderately to extensively
Since the scale of the feldspar-feldspar inter-
growths may have been submicroscopic, the species cannot
be realistically separated from potassium feldspar (KFEL).
175
Graphic Granite (GRGR)
This species included all highly ordered quartzfeldspar intergrowths.
Normal graphic granite and
myrmekite were observed.
Variation in the degree of
ordering resulted in an arbitrary separation of the species
from the salic plutonic fragments (SAPL).
Mafic Volcanic Fragments (MAVO)
Grains were assigned to this species on the basis of
their textures and the minerology of their phenocrysts.
Porphyritic textures were characteristic of the species.
The common groundmass texture was pilotaxitic but other
textures were felsophyric, variolitic or intersertal.
In
order of decreasing abundance, the phenocrysts were
plagioclase feldspar, aegirine-augite, augite, quartz,
potassium feldspar, hypersthene, and biotite.
The quartz
phenocrysts were euhedral and corroded-and were generally
similar to the angular quartz type (QUAR) described above
(p. 172).
Individual mafic volcanic grains were generally
andesite although quartz latite and trachyte grains were
recognized.
Many grains contained vesicules some of which
were filled with prehnite.
In a few samples it was necessary to make an arbitrary
separation of the species from very similar matrix (MATR)
or mafic plutonic fragments (MISC).
176
Salic Plutonic Fragments (SAPL)
Salic plutonic fragments included all disordered,
coarsely crystalline aggregates of quartz and feldspar.
The
original igneous rock is estimated to have had a composition
between diorite and granite.
The feldspars in the grains
included orthoclase, perthite, sodic plagioclase and mymekite.
As mentioned above (p.
175)
it
is not possible to
realistically separate this species from graphic granite
(GRGR).
Limestone (LIME)
Limestone grains were of two types.
The abundant type
was identical to the limestone lithotype.of the Carys Mills
Formation (p. 34).
The other type was coarsely crystalline
calcite which may have been shelly fossil material.
Chert (CHER)
The grains assigned to this species were quite heterogeneous.
Individual grains were tentatively identified as fine-grained
taff, devitrified glass, felsophyric fine-grained mafic
volcanic fragments and finely crystalline composite quartz.
Individual textures range from hypidiomorphic-granular to
variolitic.
In many samples, grains of this species could not be
177
realistically distinguished from grains of the mafic volcanic
species (MAVO) or of the composite quartz species (COMQ).
A significant error in identification is possible.
Pyroxene (PYRO)
Pyroxene grains were usually aegirine-augite or augite
although hypersthene was occassionally identified.
The grains
were generally angular and very similar to the pyroxene
phenocrysts in the mafic volcanic fragments (MAVO).
No
amphibole grains were observed in any of the samples.
Mica (MICA)
Most mica grains were biotite.
Some of the other
grains assigned to this species were muscovite or sericite.
Miscellaneous Lithic Fragments and Accessory Minerals
(MISC)
This species included a wide variety of material, none
of which was quantitatively significant and only some of which
was positively identified.
Primary minerals included calcite,
glauconite, spinel, zircon, sphene, rutile, schorlite, garnet,
and apatite.
Secondary minerals not part of the matrix
included calcite, pyrite, magnetite, sericite, limonite,
glauconite, and kaolinite.
Rocks of this species included
178
siltstone and mafic intrusive fragments.
A detailed qualitative study was made of the non-opaque
heavy mineral fraction of sandstones of the orthoquartzitic
facies.
The assemblage was characterized by the abundance
of zircon and biotite.
Sphene, rutile, schorlite, and
garnet were also present.
Matrix (MATR)
Matrix was easy to recognize and distinguish from the
coarser grained detrital fraction of the sandstones except in
samples where extensive carbonate recrystallization had taken
place.
Occassionally some matrix types were confused with the
groundmass
of mafic volcanic fragments (MAVO).
The grain size of the matrix was too small to positively
identify the mineral constituents.
One type of matrix was
cryptogranular, isotropic, dark gray, unidentified material.
A second type of matrix was a microcrystalline aggregate of
secondary "chlorite," "sericite," silica, pyrite, glauconite,
and prehnite.
A third type of matrix common in the sandstones
of the arkosic facies was mainly the second type modified by
the addition of abundant secondary calcite.
RESULTS OF ANALYSIS
The results of the modal analyses are summarized below.
179
NATR
SAMPLE
NAME
E4322EM3234
E4323b
D4323C
EM323d
E4323te
E:1558
6
8
feldspathic arenite
14
15
+74
103
138.
169
189 7
193 198 ,
215
219
220
227+228
230
COMQ PLAG KFEL PERT GRGR LITH MAVO SAPL LIME CHER ACCM PYRO MICA MISC
*
0.7
4.0 71.7
6.0
3.0 10.7
2.0
1.3
lithic wacke
arkosic wacke
lithic wacke
11.0 23.0
19.0 23.3
15.0 23.7
1.0
1.7
3.0
9.0 16.0
9.3 25.3
3.7 15.3
0.7
4.3
4.0
27.3
0.3 *
6.3 6.7 *
3.3 27.3 *
lithic wacke
11.7 36.3
3.3
6.0 10.3
3.7
lithic wacke
11.3 19.0
5.0 12.0
4.3
1.7
15.0 31.7
12.7 32.3
2.0
6.7
13.3 38.0
8.0
1.3
1.7 11.0
3.0
2.0 5.0
2.3
2.0
0.3
3.3
1.0
1.0
lithic
lithic
lithic
lithic
wacke
wacke
arenite
wacke
lithic wacke
lithic
lithic
lithic
lithic
lithic
lithic
lithic
lithic
lithic
lithic
lithic
lithic
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
arenite
231
lithic wacke
262
264a
264b
267 '
268"
271'
lithic
lithic
lithic
lithic
lithic
lithic
27-6
lithic wacke
288a
297"
371
390
441
4531
457,
Z4560
E41154
QUAR
lithic
lithic
lithic
lithic
lithic
lithic
lithic
lithic
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
wacke
arenite
wacke
lithic arenite
14.0
-
-
7.7
*
0.7
0.7
4.0
4.7
*
*
*
*
6.3 22.0 *
24.7
3.0 *
*
*
*
*
1.0 10.0
0.3
*
*
3.7
0.3
-
35.0
37.0
85.3
29.7
52.0
0.7
1.0
0.3
0.3
0.7
-
*
*
*
*
*
*
5.7
.
*
*
*
*
*
*
*
*
*
*
*
*
0.6
-
*
*
*
*
*
*
0.7
3.0
3.3
1.0
0.7
2.3
0.7
2.3
3.7
2.3
0.3
0.3
0.3
0.3
-
-
-
62.7
56.0 54.3
45.7 *
68.7 *
77.3 *
*
45.3
53.3 *
*
57.0
29.3 *
48.0 *
78.0 *
81.7 *
15.0 13.3
7.7
1.7
0.3
-
54.3 48.3
0.3
-
-
47.7
57.0
77.3
51.3
0.7
0.3 64.0
0.3 56.0
0.7
0.7 52.0 49.0
0.7
0.7
0.7
0.3
0.3
.
40 0
38.3
35.7
39.7
59.0
57.7
88.3
18.7
14.0
4.3
15.7
10.7
14.3
3.0
1.0
0.3
1.3
1.0
1.7
8.0
6.3
5.3
6.7
5.0
5.7
1.7
0.3
0.3
2.0
1.0
2.3
16.0 15.0
3.0
5.7
2.0
14.7
15.7
12.3
17.3
13.7
17.0
17.0
14.7
15.0
15.3
13.0
13.3
7.3
13.7
16.7
18.3
23.0
24.3
12.0
13.7
2.7
6.0
3.7 84.7
2.3 8.3
4.0 13.7
2.7 14.3
4.3 10.3
2.0 8.7
2.3 8.3
1.0
1.3
6.7 4.7
5.3
5.3
4.7
2.0
3.3
3.3
2.0
4.0
-
-
*
*
8.7
1.3
0.7 11.0
1.7 10.3
5.0
2.7
6.0
2.7
7.0
0.7
0.7 4.7
2.0 14.3
2.3 8.7
1.0
0.3 3.0
3.0
-
*
*
8.7
10.3
16.0
5.7
1.3
20.7
18.0
15.7
18.7
15.7
6.0
2.0
-
*
-
11.7
14.7
13.7
14.7
15.7
20.3
15.7
13.3
16.7
17.0
13.5
9.3
0.7
0.3
1.0
0.3
-
0.3
1.0
5.0
-
-
*
*
14.0
-
0.3
-
-
0.7
1.0
1.0
0.3
.
-
0.7
0.3
-
3.7
-
1.7
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
67.0
-
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.0
3.0
1.3
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
2.0
2.3
6.7
15.0
5.3
4.3
8.0
4.7
2.3
2.7
3.7
-7
3.0
-
*
*
*
*
*
*
5.3
*
*
*
*
*
*
*
-
-
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
3.3
0.3
5.3
4.3
2.7
*
*
*
*
*
*
*
*
*
*
*
*
3.6
5.3
14.3
5.7
1.5
3.3
4.7
6.0
5.7
3.3
1.0
.
0.6
5.0
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
9.0
4.0
4.0
4.0
1.3
1.3
1.0
0.7
0.7
1.3
-
-
0.3
*
*
*
*
*
*
*
1.0
*
*
2.6
-
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
-
-
2.3
-
-
*
*
180
SAMPWi
NAME
MATR QUAR CGX4Q PLAG KFEL PERT GRGR LITH MAVO SAPL LIME CHER ACCM PYRO MICA MiW
TH4J
TH65'
TH76
TH8Q
TH9 a
TH93 b
TH109a,.
TH1Q9b
Ti 11~6'
TH1 g
TH129
TH181a:
TH141b
TH254a
TH254b
TH292a
TH292b
TH294
TH304
lithic wacke
feldspathic wacke
lithic wacke
lithic wacke
lithic wacke
lithic wacke
ardosic wacke
ardosic wacke
quartz arenite
arkosic wacke
ardosic arenite
feldspathic wacke
feldspathic arenite
quartz arenite
quartz arenite
quartz arenite
quartz arenite
quartz arenite
quartz arenite
13.7
DR1009a arkosic wacke
DR1009b lithic wacke
DR1009c lithic wacke
DR1009d lithic wacke
DR102Oa lithic wacke
DR1020b lithic wacke
DR1021 lithic wacke
DR1022a feldspathic arenite
DR1022b feldspathic aren.te
D R1 023 feldsDathic arenite
DR1066a lithic wacke
DR1066b lithic wacke
1DR10.67pa lithic wacke
DR1067b lithic wacke
8.7 0.7
60.0 2.3
15.3 14.7 4.0
16.6 20.7 3.3
10.0 24.3 3.0
17.3 23.7
1.3
23.3
10.3
10.3
17.3
1.7 86.0 3.3
16.0
24.0
7.0 14.0
4.0
10.0 61.0
2.3
2.7
9.3 71.7
3.3 82.7
5.0
3.3 80.3
6.0
3.3 78.7 11.0
4.0 81.0
6.3
6.6 78.7
6.3
0.3 89.7
5,7
12.7
15.0
14.7
14.7
13.3
11.3
10.3
12.0
3.3
5.0
28.7
15.7
26.7
22.7
5.0
6.3
8.5
65.7
62.3
6.0 68.3
14.0 17.7
16.3
8.7
16.8 2.0
13.3
4.0
3.0
1.7
6.7
9.7
13.7
13.3
13.3
7.3
8.3
0.7
6.0
11.3
2.0
3.0
1.0
1.7
2.0
1.0
2 0
0.3
1.7
12.7
11.0
11.0
5.7
9.0
45.7
48.0
5.3
42.0
42.7
18.7
11.7
6.0
5.7
4.7
6.0
3 7
2.0
0.3
2.3
1.7
1.3
3.0
2.0
6.3
7.0
2.0
1.7
6.0
0.3
4.7
10.3
9.7
7.3
5.7
9.7
2.3
4.0 12.3
7.3
4.0
6.3 9.7
6.3 3.0
0.3
2.3
0.7
2.0
0.3 0.7
0.5
0.5
3.5
3.0
6,0 11.0
2.3
5,7
5.7 11.7
3.3
3.3
4.3 10.3
1.3
1.3 11.3
2.3
1.3
5.7
1.7 0.7
0.8
5,2 0.4
1.0 4.3 2.7
0.3
0.3
2.3
1.7
2.7
4.0
3.0
4.3
0.3
3.0
9.3
0.3
0.3
0.7
1.7
*
*
*
*
*
*
*
*
*
*
*
2.7
*
*
*
69.0
0.7
27.7
25.0
24.7
18.3
0.7
1.3
0.3
5.0
1.3
-0
0.3
1.0
5.0
3.0
2.3
1.7
0.7
0.7
0.5
0.7
0.3
1.7
0.3
2.7
*
*.
*
*
*
*
*
*
*
0.3
0.7
0.3
0.3
0.3
1.3
1.3
1. 7
2.6
2.0
19,
0.3
-*
2.3
4.3
*
0.3
0.3
1.0
0.7
1.0
1.0
*
*
*
0.3
0.6
0.3
24.7
28.7
20.3
*
*
*
21.3
*
*
*
*
*
*
64.7
0.3
*
*
*
-.
80.0
1.3
1.7
1.7
1.3
0.7
1.3
1.3
1.0
0.7
3.7
2.3
8.7
2.0
1.0
0.3
2.0
2.3
5.3
5.7
*
*
*
*
*
*
*
*
*
*
*
0.3
3.7
2.0
3.3
2.3
5.3
*
*
*
*
75.0
57.5
1.0
0.3
1.3
45.0
*
69.5
71.7
0.3
0.5
1.0
1.0
0.7
0.7
5.0
*
*
0.4
0.7
0,3
0.7
0.3
1.3
1.0
1.7
1.0
1.3
2.3
*
*
*
*
*
1.0
0.4
*
*
*
*
*
*
1.0
*
*
0.7
1.0
*
*
*
*
0.3
*
*
1-.
*
*
2.0
*
.07
3.3
10.0
1.3
2.3
01.7
5.0
*
4.4
'1.7
181
The symbols are'the same as those defined above
(p. 172).
The symbol " *
"
means that the particular
petrographic species was not applicable to the
analysis of the particular sample.
The symbol " -9
means that the abundance of the particular species was
zero in the analysis of the particular sample.
The
symbol " + " means that only 250 points were counted
in the analysis of the particular sample.
The lithologic
names are based on the classification of Williams and
others (1963, p. 292-293).
The abundance of the
petrographic species are expressed as percentages.
GROUPED ANALYSIS
The variation of composition of the samples is
due to the combined effect of vertical and horizontal
lithologic variations within the thesis area.
The first
factor represents the changing environment through
time at a given place.
The second factor represents
the spatial variation of the environment at a given
time. Since the first factor is relatively insignificant
in the Siegas Formation (p. 84) it is only possible to
examine the spatial variation of environment.
It is
most practical to represent this variation as an
average environment throughout the time of deposition
of the formation.
This situation can be approached
182
by minimizing the effect of vertical lithological
variations by averaging the compositions of sandstones
from the same vertical section.
This procedure leads
to the accumulation of outcrops into groups which
are given average modal compositions.
The petrographic species may be formed into
more realistic variables.
Since no genetic significance
has been found for COMQ it is combined with QUAR to
form the new species "total quartz" (TQ).
Since PERT
cannot be realistically separated from KFEL (p. 174)
the two species are combined to form the new species
"total potassium feldspar" (TKSP).
Since GRGR
could not in practice be completely distinguished
from SAPL and since the two species have similar
genetic implications, they are combined to form the new
species "total salic plutonic fragments" (TSPL).
No systematic variations of CHER, MICA, and MISC
were found so these species are disregarded.
These results were directly applied to the
construction of the facies diagram Figure 26 (p. 91)
and the petrographic variation diagrams Figures 27 to
33 (p. 93-100).
The definitions of the groups,
the average lithological classifications and the
average values of the significant petrographic
variables are summarized below.
183
GROUP
MATR
TQ
PLAG
TKSP
TSPL
MAVO
LINE
xYRO
lithic wacke
14.4
16.2 12.4
2,.3
1,1
50,6
1"o
2.3
lithic wacke
14.8
9.9
6.2
1.8
0.7
63.3
0.2
DR1021
lithic wacke
12.0
9.0
3.5
0.5
0,5
57.5
5,0
1.0
TH41
DR 1020
lithic wacke
11.8
7.7
1.6
1.0
0.1
72,0
0.7
0.5
TH65
foldspathic arenite 6.8
67.7
5.7
13.7
1.9
0.8
0.2
OUTCROPS
1:4558
DR1066
DR1067
E4560
DR1022
R1023
DR1009
lithic wacke
14.4
30.7
9.9
11.8
5.3
21.3
2.3
1.0
TH70
lithic wacke
15.3
18.7
9.7
12.7
7.3
27.7
0.3
-
TH8O0
lithic wacke
14.7
25.4 13.4
10.7
5.8
22.7
0.4
0.1
Ea322
E3 23
lithilc wacke
12.8
36.2
7.1
16.4
3.2
17.6
0.3
0.2
TH181
feldspathic arenite 9.7
68.8
3.0
15.3
0.3
0.7
-
-
TH129
ardosic wacke
7.0
18.0 11.3
48.7 12.0
1.7
TH116
arkosic wacke
8.8
56.6
3.3
25.5
1.8
0.2
TH109
arkosic wacke
10.3
20.3
7.8
53.5
5.7
1.0
TH254
arkosic wacke
3.3
87.0
1.3
5.8
1.6
TH304
arkosic wacke
0.3
95.3
0.3
2.0
0.7
TH292
arkosic wacke
4.4
87.7
1.7
4.5
1.3
TH93
TH124
TH294
E:1154
184
REFERENCES
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185
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-----
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------
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unpublished report.
FIGURE 48
OUTCROPS AND
STRUCTURA IL DATA OF THE
SIEGAS AREA , NEW BRUNSWICK
0.5
MIL ES
Too\
-TH23
SOa0
OUTCROP LOCATION
STRIKE, DIP, A ND FACING OF
BEDDING ( BEDS OVERTURNED).
)e
..
a.
S8
DE
^650-1
-'5.).
OSTO
009~
*-
RB S
0\
FIGURE 49
OF THE
NEW
LATE
SILURIAN
EARLY
SILURIAN
U...'
LU UU U
U...'
LATE
ORDOVICIAN
MIDDLE
ORDOVICIAN
SECTION LINES FOR FIGURES
38 AND 39.