Geochemistry and provenance of Archean metasedimentary rocks in the southwestern Beartooth
Mountains
by Peter Bouck Thurston
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in
Earth Sciences
Montana State University
© Copyright by Peter Bouck Thurston (1986)
Abstract:
A thick sequence of Archean metasedimentary rocks is exposed along the southwestern margin of the
Beartooth Mountains, Montana.Rock types include quartz-biotite schist, biotite schist,
biotite-garnet-staurolite-andalusite schist, iron formation (hornblende-cummingtonite-garnet schist),
and dacitic metavolcanic rocks (quartz-muscovite-plagioclase schist). Preliminary chronologic data
indicate an age of at least 3200 Ma for these racks (Paul Mueller, pers. comm.). The entire belt is
metamorphosed from greenschist to middle amphibolite facies. Peak metamorphic conditions occurred
at 550 degrees C and less than 3.8 kilobars. The entire rock package has experienced at least two
periods of structural deformation. Early isoclinal folds (F1) are coincident with peak metamorphism
(M1). Later open folds (F2) are superimposed on earlier structures. Primary sedimentary structures
such as horizontal lamination, graded bedding, cross bedding, wavy bedding, and cut and fill structures
are preserved. Analysis of sedimentary structures suggests that the rocks were originally deposited by
turbidity currents in an environment similar to the midfan portion of a submarine fan. These data
suggest deposition along an active continental margin; geochemical data indicates a provenance with
sediment input from at least two different sources, one mafic and one felsic. These rocks are chemically
unique in the northern Wyoming Province and were not derived from the adjacent Beartooth
Mountains. A chronologically and chemically compatible source terrane has not been identified. The
rocks are petrographically and chemically similar to early Archean greenstone belt sediments such as
the Fig Tree group of Eriksson (1980). Similar rocks are exposed in central Wyoming (Condie, 1967).
The style of metamorphism and deformation is sufficiently different from the surrounding region to
classify these rocks as a distinct terrane. Previous work in the region has suggested the possibility of an
Archean continental margin along the western edge of the Beartooth mountains (Wooden et al., in
press). If this is the case then the metasedimentary rocks of the South Snowy Block could have been
tectonically emplaced along this margin. GEOCHEMISTRY AND PROVENANCE OF ARCHEAN METASEDIMENTARY
ROCKS IN THE SOUTHWESTERN BEARTOOTH MOUNTAINS
by
Peter Bouck Thurston
A thesis submitted in partial fulfillment
of the requirements for the degree
of
Master of Science
in
Earth Sciences
MONTANA STATE UNIVERSITY
B o z e m a n , Montana
December ISBE
MAIN Life.
7-f^75
&Y>'c2/
ii
APPROVAL
□F a thesis submitted by
Peter Bouck Thurston
This
thesis has been read by each member of the thesis
committee
and has been Found to be satisFactory
regarding
content,
English usage,
Format,
citations,
bibliographic
style,
and consistency, and is ready For submission to the
College oF Graduate S t u d i e s .
1 I /T^6
Date
Chairperson,
Graduate Committee
Approved For the Major Department
Approved For the College oF Graduate Studies
'X, / 9 ^
Date
Graduate^Dean
iii
STATEMENT DF PERMISSION TO USE
In presenting this thesis in partial Fulfillment of the
requirements
For
a
m a s t e r ’s
degree
at
Montana
State
U n i versity, I agree that the Library shall make it available
to
From
borrowers under rules. oF the L i b r a r y .
Brief
this thesis are allowable without special
quotations
permission,
provided that accurate acknowledgment of source is m a d e .
Permission For extensive quotation From or reproduction
of this thesis may be granted by my major professor,
his
absence,
opinion
scholarly
by
the Director of Libraries
of either,
purposes.
when,
or
in
in
the
the proposed use of the material is For
Any copying or use of the material
this thesis For Financial gain shall not be allowed
my written p e r m i s s i o n .
in
without
iv
ACKNOWLEDGEMENTS
I
mould
Company,
like
Inc.
to thank the American Copper
and
Nickel
For their generous Financial support oF this
r e s e a r c h . I would also like to thank John R a y , John C u t h i l l ,
Paul
Mueller,
and
Joe
Wooden
For
discussions and critical reviews oF this
many
enlightening
manuscript.
Randi
Hovin provided invaluable assistance with preparation oF the
diagrams.
V
TABLE DF CONTENTS
Page
INTRODUCTION................................................
I
GENERAL G E O L O G Y ............................................
3
METASEDT MENTARY R O C K S .................................
5
Quartz-Biotite S c h i s t ...................................
Biotite S c h i s t ......................
Iron F o r m a t i o n ...........................................
5
IB
22
METAVOLCANIC R O C K S .........................................
26
PLUTONIC R O C K S .......
29
METAMORPHIC G R A D E ..........................................
30
S T R U C T U R E ...................
33
ENVIRONMENT OF D E P O S I T I O N .................................
36
P R O V E N A N C E .......
42
D I S C U S S I O N ..........
45
R E F E R E N C E S ..................................................
52
A P P E N D I C E S ..................................................
SB
Appendix A - Analytical M e t h o d s ........................
Appendix B - D a t a .........................................
SS
GE
vi
LIST OF TABLES
Table
Page
I . Major and trace element g e o c h e m i s t r y ................
15
2. Comparison of South Snowy Block greywackes with
other Archean greywackes w o r l d w i d e .......... '.........
17
3. Comparison of South Snowy Block mudstones with
other Archean m u d s t o n e s .................................
21
4. Major element geochemistry of Wyoming Province
iron F o r m a t i o n s ..........................................
23
5. Major element geochemistry of metavolcanic rocks
and common igneous r o c k s ................................
27
6 . Modal analyses of metag r e y w a c k e ........................
57
7. Rare earth and trace element data for South Snowy
Block metasedimentary r o c k s ............................
6B
B . ICP geochemical d a t a ....................................
SB
vii
LIST OF FIGURES
Figure
'
Page
1. Geologic map of the Beartooth M o u n t a i n s ...............
I
2. Distribution of metasedimentary rocks in the
South Snowy B l o c k ........................................
4
3. Photomicrograph
of monocrystalline quartz g r a i n s ....
7
4. Photomicrograph
of a polycrystalline quartz grain....
5. Photomicrograph
of a detrital plagioclase g r a i n ......
8
G . Photomicrograph of a large lithic F r a g m e n t ............
9
7. Horizontal laminations and ripple cross stratifi­
cation in Fine grained quartz-biotite s c h i s t .........
11
8 . Sedimentary structures in quartz-biotite s c h i s t .....
12
8 . Rip-up clasts in quartz-biotite s c h i s t ................
12
10. Basal contact of comglomerate Filled s c o u r , .........
13
11. Major element distribution in metasedimentary r o c k s .
16
12. Rare earth
element distribution in m e t a g r e y w a c k e ....
18
13. Rare earth
element distribution in biotite schist...
21
14. Rare earth
element distribution in iron Formation...
24
B
15. Normative Ab-Or-An plot of Feldspar p o r p h y r y ........
28
16. Discontinuous reaction in biotite s c h i s t ............
31
17. Pressure and temperature of peak m e t a m o r p h i s m .......
32
18. S t e r e o n e t s ...............................................
35
IS. Measured section From the central part of the belt..
33
20. Model of depositional environment showing location
of observed sedimentary s e q u e n c e .....................
41
viii
LIST DF FIGURES - continued
Figure
Page
S I . Major element composition plots of sandstones
For tectonic setting d i s c r i mination ..................
43
ES. Trace element variation in northern Wyoming
Province metasedimentary r o c k s ........................
46
S3.
48
Inferred configuration of the depositional setting..
ix
ABSTRACT
A
thick
sequence of Archean metasedimentary
rocks
is
exposed
along
the southwestern
margin
of
the
Beartooth
M o u n t a i n s , Montana.Rock types include quartz-biotite schist,
biotite schist, biotite-garnet-staurolite-andalusite schist,
Iron formation Chornblende-cummingtonite-garnet schist), and
dacitic
metavolcanic
rocks
Cquartz-muscovite-plagioclase
schist).
Preliminary chronologic data indicate an age of at
least 3200 Ma for these rocks (Paul M u e l l e r , pers.
comm.).
The
entire belt is metamorphosed from greenschist to middle
amphibolite f a c i e s . Peak metamorphic conditions occurred at
550 degrees C and less than 3.8 k i l o b a r s . The entire
rock
package
has experienced at least two periods of
structural
d e f o r m a t i o n . Early isoclinal folds (F1) are coincident with
peak
metamorphism
(Mi).
Later
open
folds
(F3 )
are
superimposed
on earlier
structures.
Primary
sedimentary
structures
such as horizontal lamination, graded b e d d i n g ,
cross b e d d i n g , wavy b e d d i n g , and cut and fill structures are
p r e s e r v e d . Analysis of sedimentary structures suggests that
the rocks were originally deposited by turbidity currents in
an environment similar to the midfan portion of a submarine
fan.
These
data
suggest
deposition
along
an active
continental m a r g i n ; geochemical data indicates a provenance
with sediment input from at least two different sources, one
mafic and one f e l s i c . These rocks are chemically unique
in
the northern Wyoming Province and were not derived from the
adjacent
Beartooth
Mountains.
A
chronologically
and
chemically
compatible
source
terrane
has
not
been
identified.
The rocks are petrographically and
chemically
similar
to early Archean greenstone belt sediments such
as
the
Fig Tree group of Eriksson (1980).
Similar
rocks
are
exposed
in central Wyoming (C o n d i e , 1957).
The style
of
metamorphism and deformation is sufficiently different
from
the surrounding region to classify these rocks as a distinct
terrane.
Previous
work
in the region has
suggested
the
possibility
of
an
Archean continental
margin
along
the
western edge of the Beartooth mountains (Wooden et a l .,
in
p r e s s ) . If this is the case then the metasedimentary rocks
of
the South
Snowy Block
could
have
been .tectonically
emplaced along this m a r g i n .
I
INTRODUCTION
Archean
belt
metasedimentary
rocks are exposed in a
narrow
along the southern margin of the South Snowy Block
the Beartooth Mountains in southwestern Montana (Figure
These
rocks
CCondie,
excellent
are
1976)
unique in the northern
because
preservation
of their
are
CCondie,
reported
1967),
from
Similar
the southern
Range in the southern Wyoming Province,
grade,
structures,
metasedimentary
Wind
the Owl Creek Mountains,
13.
Province
metamorphic
of primary sedimentary
and distinct chemical composition.
rocks
low
Wyoming
and
River
Range
Rattlesnake
but comparable rocks
are not known to exist in the northern Wyoming P r o v i n c e .
LIVINGSTON
L UTertinry volcanic rocks
DEI]Paleozoic sedimentary rocks
t::: ] Archean metasedimentary rocks
NORTH
SNOWY
BLOCK
I
B E ARTOOTH
PLATEAU
BLOCK
of
Stillwater Complex
I Arche on granites and gneisses
RED
LODGE
GARDINER
cJlTYt
25 km
Figure I. Geologic map of the Beartooth Mountains.
2
Previous
research
on Archean rocks in the South
Snouiy
Block in general has been limited to a regional study
along
the southern margin of the block CCasella et a l ,
addition,
specific
projects
concentrated
mineralization in the Jardine area
on
1982).
the
In
gold
CSeager, 1944, Hall a g e r ,
1980) and surface geology of the Gardiner Quadrangle CFraser
et al,
1989).
This
central
study
part
evaluation
of
the
metasedimentary
belt
CFigure
2).
rocks
The
of the sedimentology and geochemistry
here
suggests
from
a
of
mafic
and
style of metamorphism,
that
from
the
systematic
presented
that the metasedimentary package was derived
combination
p r o venance,
suggest
examines
the
entire
felsic
sources.
The
and style of deformation
metasedimentary
tectonically emplaced in the late A r c h e a n .
package
was
3
GENERAL GEOLOGY
Archean metamorphic and igneous rocks oF the South Snowy
Block are For the most part covered by Eocene volcanic rocks
and
surFicial deposits.
the
block
are
metasedimentary
Only along the southern margin
Archean
sequence
rocks
is
well
oF
exposed.
bordered on the
The
east
by
an
Archean batholithic complex CCasella et a l , ISBSD consisitng
oF
an early quartz-hornblende diorite and younger tonalites
and granites (Wooden et a l .,
the
metasedimentary
several
oF
rocks
these, p l u t o n s .
in p r e s s ) .
is
The
constrained
Crevice
intrudes the central part oF the belt,
to
2,730
These
Ma by Rb/Sr and K/Ar
The minimum age oF
by
ages
granite,
which
is dated at S 1BSO Ma
methods
(Brookins,
data are supported by a Rb/Sr model age on
ISBBD.
muscovite
oF S ,74:0 + 30 Ma For the Hellroaring Mountain stock
et al.,
2,730
the
I S B S D . A U-Pb zircon age analysis suggests an age oF
eastern part oF the metasedimentary belt
these
In
intrudes
(Montgomery,
the northern and southern portions oF the
metasedimentary rocks are covered by Eocene
rocks.
shear
To
the
west,
zone in the Yankee Jim Canyon area
angle
ISBSD .
reverse
area,'
volcanic
the belt is terminated by a
ductile
(Burnham,
The southwest corner is truncated by the Gardiner
high
(Wooden
to S ,790 Ma For a biotite granodiorite that
ISBSD .
From
1SB0D.
Fault,
Fault oF Laramide age (Eraser'
et
a
al,
DBiB
4
Cenozoic volcanic rocks
Mesozoic S Poleozoic sedimentary rocks
Archeon granite
Archean metasedimentary rocks
Note: surlicial deposits omitted for clarity.
2
3
4
5 km
Figure 2. Distribution of metasedimentary rocks in the South
Snowy B l o c k .
5
METASEDIMENTARY ROCKS
Metasedimentary rocks are the oldest lithologic units in
the study area. These rocks are metamorphosed From the upper
greenschist
grade
to
middle amphibolite Facies with
increasing
deFined
by
present
to
the
east.
A
metamorphic
parallel alignment oF biotite and
throughout
the
region,
metamorphic
and
is
Foliation
chlorite
locally
is
very
pronounced.
Rock
types
schist,
in the study
biotite
schist,
area
schist,
silicate
and
metaconglomerate,
and
quartz-biotite
biotite-staurolite-andalusite
garnet-biotite-chlorite
Cboth
include
schist,
oxide
iron
Formation
Facies),
quartzite
Felsic metavolcanic rocks
muscovite-plagioclase s c h i s t ) .
(quartz—
Each oF these lithologies is
described ' in terms oF its Field appearance and p e t r o graphy.
Selected
samples are analyzed For major and
geochemistry.
For
a
complete
description
trace
oF
element
analytical
methods and listing oF data reFer to Appendices A and B .
Quartz-Biotite Schist
Quartz-biotite
region.
the
In outcrop the rocks are light grey to medium brown
in c o l o r .
deFined
schist is the dominant lithology in
by
Individual
sedimentary
Bedding is well exposed in many locations and
abrupt
beds
are
changes
in
grain
5.0
to 25.0
size
and
centimeters
is
texture.
thick
textures and structures such as grading,
and
cross
6
bedding,
and
cut and Fill structures are often
preserved.
The rock is poorly sorted and is composed of detrital quartz
and feldspar grains set in a matrix of q u a r t z ,
b i o t i t e , and
chlorite.
Two
varieties
MonocrystalIine
commonly
of detrital quartz grains
quartz
grains are the most
millimeters
and
Polycrystalline
and
Individual
range in size from 0.1 to 2.0
subrounded
to
quartz grains tend to be
sutured grain boundaries,
(Figure
to
are
present.
abundant,
exhibit undulose extinction (Figure 3).
monocrystalline quartz grains
have
are
subangular.
slightly
and are commonly
larger,
Fractured
. Individual polycrystalline quartz grains are 1.0
2.0 millimeters in size and are subrounded to subangular
A gradation between the two types exists.
quartz
grains
Both varieties of
are flattened and elongated in the plane
of
the F o l i a t i o n .
Plagioclase
0.5
to
occurs
as subrounded detrital grains
2.0 millimeters in diameter
quartz inclusions (Figure 5).
igneous
textures
twinning
are
recrystallization.
(Michel-Levy)
grains
such
are
foliation.
as oscillatory
zoning
despite
Compositions
range
contain
abundant
Original grain boundaries and
preserved
methods
and
from
from
determined
An34-An3 I.
and
albite
metamorphic
by
optical
Plagioclase
also aligned and flattened in the plane of
the
7
Figure 3.
Photomicrograph of monocrystalline quartz grains.
Probable
lithic Fragments
portion oF the detrital grains.
composed
(Figure Gl also constitute a
Angular to subrounded grains
of aggregates of quartz and plagioclase are 0.5 to
2.0 millimeters in size.
The plagioclase occurs as optically
discontinuous aggregates of euhedral crystals suggesting
igneous origin.
an
Positive identification of any specific rock
type is difficult because of recrystallization,
however most
appear to be Fragments of tonalite or trondhje m i t e .
8
Figure 5. Photomicrograph of a detrital plagioclase
grain.
9
Figure 6 . Photomicrograph of a large lithic Fragment.
The matrix is composed of granoblastic q u a r t z ,
biotite
and
crystals.
chlorite,
Plagioclase
composition
to
and
in
small
the
euhedral
matrix
generations
chlorite
oF
occur
plagioclase
has
a
the detrital plagioclase grains
that recrystallization of the Feldspars was
biotite are p r e s e n t .
similar
suggesting
complete.
Primary
as thin laths and deFine the
laths of
biotite
primary
Two
and
CFiD
Foliation which is parallel to observed lithologic c o n t a c t s .
Secondary biotite and chlorite occur as blacky crystals that
cut
across
the
incipient secondary
primary
CFxD
Foliation
CF=D F o l i a t i o n .
and
deFine
an
10
Porphy rob last S'
samples
From
metamorphic
of
the
garnet and staurol i te are common
eastern
portion
of
the
grade is above the staurolite
in
area
where
isograd.
Garnet
porphyroblasts are euhedral and contain inclusions of quartz
and
biotite.
Staurolite is subhedral and has inclusions of
quartz.
Accessory minerals include tourmaline,
apatite, zircon,
and m a g n e t i t e . Zircons are sub h e d r a l , show strong pleochroic
halos in' b i o t i t e ,
and lack visible metamorphic overgrowths.
Under plane light the tourmalines typically
have deep b l u e ,
f
rounded
cores
surrounded
by
euhedral
yellow-green
overgrowths.
pop u l a t i o n ,
The
blue
cores may be part of
suggesting
the
detrital
that tourmaline was present in
the
source a r e a .
The
most
layering.
Graded
common sedimentary Feature
Individual layers are 0.5 to 50 centimeters t h i c k .
units.
increases
In individual graded beds
centimeters
to
25.0
stratiFication,
(Figure
coarser-
biotite
content
towards the top with a corresponding decrease
detrital quartz and pl a g i o c l a s e .
(Figures
compositional
bedding is typically well developed in the
grained
bedding
is
are
well
7 and 8 ).
5).
A
Single graded beds are 2.0
centimeters t h i c k .
ripple
cross
developed in
in
Low
angle
stratiFic a t i o n ,
the
Finer
cross
and
grained
wavy
units
Possible rip up clasts are also present
channel scour Filled with
conglomerate
present in an outcrop in the central part oF the study
is
area
11
(Figure
10).
This Feature is 3.0
maximum of I meter t h i c k .
meters in width and is a
The basal contact of the scour is
sharp. The upper contact is gradational into coarse g r a i n e d ,
quartz-biotite s c h i s t .
diameter
and
are
Clasts are 0.5 to 2.0 millimeters in
mostly
monocrystalline
subordinate plagioclase and lithic Fragments.
quartz
with
The matrix is
composed oF quartz and biotite.
Figure 7. Horizontal laminations and ripple cross stratiFication in Fine-grained quartz-biotite schist.
12
Figure 8. Sedimentary
structures in quartz-bictite schist.
Vertical
lines are glacial
striation s . Bedding
CS0 ) and primary foliation CS1) are parallel to
pencil .
Figure S . Rip-up clasts in quartz-bictite schist.
13
Figure 10. Basal contact of conglomerate-filled scour.
Modal
B,
analyses of 20 quartz-biotite schists Csee
Appendix
protolith
B) suggests a
Cafter
material is high
Folk,
subarkosic sandstone
1374).
Table
as
The proportion of
the
matrix
C19 to 23 %); consequently these rocks are
classified as greyuiackes.
Major
and trace element analyses of 13 greywackes
the South Snowy Block
from
are presented in Table I . These rocks
exhibit a wide range of silica values that roughly correlate
with
grain
size.
The highest SiO3 contents are
found
in
coarse grained rocks with the highest percentage of detrital
quartz
respect
grains.
The
distribution of
major
elements
to SiO3 content is presented in Figure
11.
with
Al3O 3 ,
14
FeD,
and
MgO
distribution
observed
is
erratic and does not
petrologic
increasing
in
all decrease with increasing SiO^.
the
Features.
correlate
The increase in
The
CaD
with
any
Na3D
with
SiD3 is related to abundant detrital plagioclase
coarser-grained rocks and
possibly
to
diagenetic
albitization of Feldspar C e .g . B o l e s , 19825. The increase in
K3D
with
relative
Finer
decreasing S iO 3 is related to an increase in
porportion
grained
metagreywackes
are
unique
K3 D :Na3D
in
oF matrix material
rocks.
When
compared
CTable '25 the South Snowy
their
low
CaO
ratio Cup to 2.75.
high
to average.
concentrations
transition
metals.
(biotite)
in
to
Archean
other
Block
content
the
greywackes
and
high
Concentrations oF EeD and
are slightly elevated and SiD3 ,
close
C<2%5
the
MgD
A l 3D 3 , Na3O and K 3O are all
The South Snowy Block greywackes contain
oF trace
elements,
Concentrations ,oF
between 50 and 100 ppm and Mn,
300 and 400 ppm CTable 15.
Cr,
particularly
Zn,
N i ,arid
and Ba are all
U
the
are
between
Table I. Major and trace element geochemistry.
2
8530
3
8536
I
8560
5
8535
6
8562
7
8531
8
8585
9
8550
10
8531
11
8512
12
8553
13
8563
11
8573
15
8578
16
8556
17
AVGl
18
AVG2
19.3
0.67
18.0
11.0
0.09
5.06
1.71
3.00
3.15
6.05
56.3
0.77
19.6
9.53
0.12
1.57
0.66
0.76
3.39
2.88
55.9 56.0
0.67 0.73
18.6 18.2
9.85 10.53
0.09 0.12
1.19 1.36
0.72 1.11
1.12 1.51
3.85 3.32
3.31 2.21
57.6
0.68
16.1
9.23
0.10
5.23
1.06
1.51
3.90
2.93
60.0
0.61
16.5
7.68
0.11
1.05
2.13
3.01
1.93
2.72
66.5 61.6
0.59 0.60
11.5 15.0
7.95 10.51
0.07 0.07
3.11 3.96
0.70 0.70
1.22 1.08
2.86 3.15
1.57 2.08
69.1
0.18
13.1
5.53
0.09
2.51
1.90
2.72
2.29
1.55
72.6
0.13
11.6
1.60
0.06
2.26
1.29
3.02
1.91
1.20
73.1
0.16
11.6
5.36
0.06
2.10
0.87
2.32
2.26
1.71
69.6
0.53
11.9
6.19
0.06
3.18
1.13
2.31
2.17
1.97
73.8
0.11
10.8
1.77
0.08
2.12
1.21
2.20
1.72
1.60
71.8
0.39
11.1
3.18
0.07
1.67
1.50
2.77
1.91
0.91
75.8
0.10
10.5
1.36
0.08
1.80
1.56
2.31
1.69
1.17
56.5
0.69
17.5
9.28
0.10
1.18
0.91
1.51
3.32
1.23
66.6
0.51
13.9
6.95
0.08
3.19
1.23
2.11
2.51
1.92
K20/Na20 3.63 1.15 1.16 2.71 2.20 2.58 0.63 2.31 2.92
FeOtMgO 11.12 16.06 11.10 11.01 11.89 11.16 11.73 11.36 11.50
0.81
8.07
0.63
6.86
0.97
7.76
0.93
9.67
0.78
7.19
0.69
5.15
0.72 2.16 1.20
6.16 13.76 10.11
Analysis
I
Sample No. 8511
Si 02
Ti 02
Al 203
FeO
MnO
MgO
CaO
Na20
K20
LOI
Total
Mo
Cu
Pb
Zn
Ni
Co
Mn
As
Th
Sr
Bi
V
La
Cr
Ba
B
H
61.0
0.61
15.0
7.30
0.09
3.82
0.11
0.86
3.12
3.76
99.03 98.33 98.58 98.60 98.15 98.61 98.80 99.37 98.78 99.30 98.97 100.1 99.37 99.07 98.90 99.70 98.65 99.06
2
37
5
90
120
23
510
3
2
11
5
100
210
33
550
2
7
21
5
12
6
2
110
2
-
-
-
-
3
67
~
220
120
2
3
2
160
~
150
920
2
3
2
18
130
32
I
2
I
19
9
39
131
22
510
19
7
6
2
93
30
222
282
2
I
3
19
6
31
160
27
250
13
-
2
150
350
730
2
3
I
81
13
109
178
29
670
27
13
6
6
92
26
361
377
3
I
1-3 Biotite Schist
1-6 Fine Grained Quartz-Biotite Schist
9-12 Mediun Grained Quartz-Biotite Schist
Note: Major elements determined by XRF, Trace
3
65
5
97
120
25
760
2
-
2
120
390
210
I
2
7
21
15
16
89
16
328
2
8
5
2
83
11
212
500
2
I
3
38
12
30
80
11
176
122
8
6
2
102
32
218
189
2
I
I
17
6
80
120
25
150
2
-
2
93
-
100
510
2
2
I
11
13
67
59
12
511
93
11
7
I
75
33
292
178
2
I
6
23
17
29
53
12
118
37
9
7
2
63
27
217
331
I
I
6
128
10
80
77
21
110
18
11
8
6
68
21
310
365
7
I
13-16 Coarse Grained Quartz-Biotite Schist
17 Average Biotite Schist
18 Average Quartz-Biotite Schist
elements determined by ICR.
7
52
11
65
72
16
305
10
9
7
I
18
23
231
219
2
I
8
18
10
59
13
9
558
11
8
7
2
15
23
212
251
I
I
6
16
7
62
58
11
378
18
9
8
3
61
23
231
511
2
I
I
21
5
67
112
19
510
2
0
0
2
82
0
267
357
2
3
5
16
10
59
95
19
111
29
7
5
3
81
19
292
111
2
I
K 2 O W T % N a 2 O W T % CaO W T %
MgO W T %
FeOWT%
AI O - W T 0A
16
SiO2
WT %
Figure 11. Major element variation diagram For
metasedimentary rocks.
17
Table 2. Comparison of South Snowy Block greywackes with
other Archean greywackes worldwide. Data presented
are weight percent of o x i d e s .
I
SiO=
66.65
TiO=
0.54
Al=0.3
13.85
6.95
FeO
3.19
MgO
1.23
CaO
2.11
Na=O
2.54
K=O
K=OZNa=O 1.46
FeO+MgO 10.1
2
3
64.3
0.5
15.6
5.3
3.6
4.2
2.9
2.5
0 .85
8.9
4
7
6
5
8
82.8
65.6
70.7
64.7
53.4
68.1
0.3
0.6
0.4
0.7
0.6
0.6
15.8
8.1
15.0
15.7
14.0
10.9
2.9
4.7
6.0
6.7
6.4
5.3
3.2
1.2
3.7
4.8
2.8
4.8
1.8
2.3
5.9
2.1
3.4
I .8
0.5
3.8
4.2
3.1
3.2
1.9
0.9
2.0
2.5
1.7
2.4
2.0
0.77
0.48
0 .66 1.80
0.63
0.89
4.1
8.4
9.2
8.1 11.5 11 .2
1. Average of 13 greywackes, South Snowy Block, Montana, USA (this paper).
2. Average of 4 greywackes, Vermillion District, Minnesota, USA !Arth and Hanson, 1975).
3. Average of 3 greywackes, Burwash Fm., Slave Province, Canada (Henderson, 1975).
4. Average of 17 greywackes, Sheba Fm., Barberton Mountain Land, South Africa (Condie et al, 1970).
5. Average of 7 greywackes, Belvue Road Fe., Barberton Mountain Land, South Africa (Condie et al, 1970).
6. Average of 10 greywackes, Chitaldrug Schist Belt, India, (Naqvi and Hussain, 1972).
7. Average of 23 greywackes, Wind River Mountains, Wyoming, USA (Condie, 1967).
8. Average of 2 greywackes. North Spirit Lake, Superior Province, Canada (Donaldson and Jackson, 1965).
Rare
in
earth element patterns for two greywackes are depicted
Figure 12.
enrichment
12.4.
A
quartzite
The
greywackes exhibit
a
pronounced
LREE
and HREE depletion with La/Yb values of 7.2
medium
grained
greywacke
(sample
metaconglomerate (sample 8563) both
negative Eu a n omalies; the EuZEue
8544)
have
and
and
a
slight
values are 0.76 and 0.88.
These patterns are typical of quartz intermediate greywackes
as described by Taylor and McLennan (1985).
18
8563
8544
La Ce
Sm Eu (Gd) Tb
Yb Lu
Figure IB. Rare earth element distribution in metagreywacke.
Biotite Schist
Biotite schist is a distinct rock unit consisting of 50%
or more biotite and little or no detrital quartz.
It is not
as
still
abundant
as
quartz-biotite
important
component
especially
in
metapelites
minerals.
the
are
quartz
muscovite, sericite,
is
an
sequence,
The biotite
schists
are
composed primarily of
biotite
and
with
Porphyroblasts
andalusite are common.
but
metasedimentary
the Jardine area.
which
recrystallized
of
schist
a
of
variety
garnet,
of
metamorphic
staurolite,
and
Accessory minerals include chlorite,
plagioclase,
tourmaline,
and zircon.
19
A metamorphic Foliation CFi) is pervasive and is defined
by
parallel
incipient
and
is
alignment of biotite and
laths.
second Foliation CF=) is visible in thin
defined
crenulation
by
space
alignment of secondary
cleavage.
Two distinct
biotite and chlorite growth are present.
is
chlorite
elongate
and
the
secondary
An
section
biotite
in
generations
a
of
The primary biotite
biotite
is
blacky
and
crosscuts the F, Foliation.
Porphyroblasts
millimeters
shaped
garnet
in d i a m e t e r .
trains
contain
of
of
linear
range
0.5
to
Syn-kinematic garnets contain
inclusions.
inclusions
from
which
Post-kinematic
are
parallel
2.0
S-
garnets
to,
and
helicitically o v e r g r o w , the F x f o l i a t i o n . Inclusions consist
of q u a r t z , b i o t i t e , and chlorite with minor tourmaline.
Staurolite
size
porphyroblasts are 0.1 to 3.0 millimeters in
and contain abundant inclusions of
biotite,
and g a r n e t .
deformation,
but
quartz,
chlo r i t e ,
Most of the staurolite grew prior
to
some is syn-kinematic as evidenced by
S-
shaped inclusion trains.
Andalusite porphyroblasts are 5.0 to 10.0 millimeters in
size.
In
most
metamorphism
original
to
cases
form
andalusite has
muscovite
porphyroblastic
Form.
undergone
with
retention
Most
of
the
retrogade
of
the
andalusite
crystals are rotated in the plane of the foliation.
The fine grain s i z e , abundance of micas,
mineral
assemblages
and metamorphic
in the biotite schist suggest that
it
was originally deposited as
element
chemistry
Compared
-Ali2O3j
to
For
Complete major and trace
these rocks is given
the greywacke
FeO,
muds.
,
in
the mudstone is
Table
enriched
I.
in
M g O , and K 3O and depleted in CaO and Na3O . The
K3 O :Na3O ratio Cup to 4.4) is higher as is the total FeO+MgO
content Cup to IB.0B).
CTable 3),
in
CaO
Compared to other Archean
mudstones
the South Snowy Block mudstones have a depletion
and
distribution
grey w a c k e ,
a
of
relatively
major
high
K3 OiNa3O
ratio.
elements is quite
similar , to
although quartz content is l o w e r .
data CTable I) show concentrations oF Cr,
Overall
Ni,
the
Trace element
Zn, Co, U and
Ba slightly higher than those in the g r e y w a c k e s .
Rare
earth
samples
element geochemistry of two biotite
is presented in Figure 13.
enriched.
La/Yb
Both samples
ratios are 2.4 and 8 .8 .
schist-
are
LREE
Sample 8530 has a
negative Eu anomaly with a EuZEuw value of 0.77. Sample 8536
has
a
slight positive Eu anomaly with a
1.08.
These
which
probably
source.
EuZEuw
value
two samples define a wide range of REE
Sample
reflects
values
contributions From more than
8530 is very similar to the
may have been derived From the same area. ■ Sample
has
a
LaZYb and low total REE a b u n d a n c e .
one
metagreywacke
and
distinct mafic REE signature
of
characterized
by
8536
low
21
Table 3. Comparison of South Snowy Block mudstones with
other Archean m u d s t o n e s . Data presented are weight
percent of o x i d e s .
3
2
I
SiO=
SB. 5
TiOz
0.7
AlzO3
17.5
3.3
FeO
4.5
MgO
0.9
CaO
1.5
Na=O
3.3
KzO
3.1
KzO/N&zO
13.8
FeO+MgO
SB. B
0.9
21.3
8.3
4.9
2.0
2.9
2.8
1.0
13.2
SE.2
I .0
21 .B
8.6
5.0
1.3
2.3
3.7
I .B
13.6
4
63.9
0.8
20.1
6.6
2.4
0.4
2.8
2.6
0.9
9.0
5
61.8
0.6
14.3
11.8
6.7
I .0
1.1
2.5
2.3
18.5
6
65.4
0.4
22.1
4.0
0.5
2.0
2.4
3.6
I .5
4.5
7
60.8
0.7
24.1
5.5
3.5
0.01
0.6
4.8
8.0
9.0
1. Average of 3 mudstones, Beartooth Mountains, Montana, USA (this study).
2. Average of 3 eudstones, Burwash Fm., Slave Province, Canada (Henderson, 1975).
3. Vermillion District, Knife Lake (Grout, 1933).
4. Minnetaki Group, Superior Province, Canada (Walker and PettiJohn, 1971).
5. Average of 5 mudstones Fig Tree Group, Barberton Mountain Land, South Africa (Condie et al, 1970).
6. North Spirit Lake, Superior Province, Canada (Donaldson and Jackson, 1965).
7. Average of 10 mudstones, Gorge Creek Group, Pilbara Block, Western Australia (McLennan, 1983).
o— 8 5 3 0
8536
La Ce
Nd
Sm Eu (Gd) Tb
Yb Lu
Figure 13. Rare earth element distribution in biotite
schist.
22
Iron Formation
Iron
formation
occurs
discontinuous outcrops
horizons
I
throughout
the
1-10 meters t h i c k .
study
area
in
Several distinct
exist and tentative correlations' can be made up to
kilometer along strike.
surrounded
Individual horizons are
by a halo of garnet-chlorite schist
or
usually
garnet-
chlorite-biotite s c h i s t .
Both
present
silicate
and
study area.
and oxide facies of iron
are most abundant in the western part
meters thick in outcrop.
tie
of
are
the
The silicate facies iron formation is a massive
hornblende-quartz-cummingtonite-garnet
bow
formation
rock that is I to
2
Cummingtonite occurs as thin laths,
shaped crystals,
crystals’.
Cummingtonite
grunerite.
Hornblende
and as radiating
crystals
occurs
are
as
aggregates
often
elongate
rimmed
laths
and
of
by
is
commonly replaced by b i o t i t e . Porphyroblasts of garnet up to
I
centimeter in diameter are common and contain
of q u a r t z ,
defined
ho r n b l e n d e ,
by
and cummingtonite.
parallel
orientation
of
inclusions
The foliation is
hornblende
and
cummingtonite.
Oxide
facies
iron
formation
hornblende-cummingtonite-quartz
magnetite
Alternating
are
25-50
and
commonly
layers
a
thinly-laminated
rock with up to 20
to
3
percent
thick.
Magnetite
is
percent
pyrrhdtite.
of hornblende-cummingtonite and
millimeters
throughout the r o c k .
I
is
quartz
disseminated
23
In
three
the
surrounding garnet-chlorite
morphologies
of g a r n e t .
schist
Pre-tectonic
there
are
garnets
have
linear inclusions and have been rotated with respect to each
other.
shaped
Syntectonic
garnets have a snowball texture and
i n c l usions.
Post-tectonic
garnets
S-
helicitically
overgrow the existing Foliation.
Table Ht. Major element geochemistry of Wyoming Province iron
Formations. Data presented are weight percent oF
oxides.
I
2
3
4
6
5
SiO2
47.6
44.2
45.5
SB. S 50.9
48.1
TiO2
0.3
nd
0.06
0.36
0.28
0.2
Al2O3 S.49
1 .80
6.39
4.46
7.15
3.85
Fe2 O3* ES. B 36.6
35.6
47.8
45.1
39.4
0.2
0.64
MnO
0. IS
0.2
0.16
0.09
MgO
4.85
3.55
3.53 2.36
2.80
3.82
6.24
1.31
3.01
CaO
4.61
3.66
4.38
0.71
0.62
1.22
0.34
0.51
0.24
N a 2O
0.36
0.07
0.26
0.08
0.14
K2O
0.22
Total 101.9 102.5 100.5 100.2 101.6 100.7
(Total iron as Fe2Q3
1-4. South Snowy Block Iron Formation (Casella et al,1982).
5. Oxide Iron Formation, South Pass, Wyoming (Pride and Hagner, 1972).
6. Silicate Iron Formation, Montana (Iooega and Klein, 1976).
Compared
Province
to
other
(Table 4),
iron Formations
From
the South Snowy Block iron
are enriched in SiO53,
TiO2 ,
the
Wyoming
Formations
A l 2O 3 , and CaO and depleted in
total Fe. They also have high Cr, Ni, U , Ba, and Co contents
which is consistent with the enrichment oF these elements in
the
clastic
element
metasedimentary rocks (Table
concentrations
are illustrated in
I).
Rare
Figure
earth
S.
The
24
silicate
total
Facies
iron Formation Csample 110236) has
REE abundance,
anomaly,
a La/Yb ratio oF 2.7,
and a Eu/Eu* value oF 0.80.
has a lower total REE abu n d a n c e ,
a
low
a negative
Eu
The oxide Facies rock
a La/Yb ratio also oF 2.7,
and a Eu/Eu* value oF 0.95. The reason For the diFFerent Eu
o— 110235
8524
10
W
0)
t5
O
_C
5
O
xN
SC
O
O
_0 )
o
2
_c
La Ce
Nd
S m Eu (Gd) Tb
Yb Lu
Figure 14. Rare earth element distribution oF iron
formation.
anomalies
is
Formations
not
clear.
It is possible that
have undergone complex diagenetic
these
iron
changes
that
could have altered the original REE abundances C e .g .
1983).
The
hydrothermal
lack
oF
Fluids
a negative Eu anomaly
may have been
during deposition (Fryer,
1983).
a
suggests
contributing
Fryer,
that
Factor
Both iron Formations have
mafic REE signatures similar to one of the mudstones (sample
853B3
suggesting
petrogenesis.
Involvement
of
mafic
rocks
in
their
EB
METAVOLCANIC ROCKS
Felsic
metavolcanic
rocks
are
interbedded
with
the
metasedimentary rocks in the central part of the study area.
They
Farm
distinctive
meters
thick.
bedding
in
reveals
local
Although
white to
aran'ge^tan
they seem to be
the metasedimentary
units,
discordances of 2-5
outcrops
1-3
concordant
close
degrees
with
examination
along
,s t r i k e .
Seven horizons are identified within the study area although
some
of
rocks
are
these may represent structural
repetition.
have not been previously documented in the
interpreted
deposits.
to
be either porphyritic
sills
These
area
and
or
tuff
These rocks have a pronounced foliation defined by
crude alignment of micas and elongation of phenocrysts.
texture
is
porphyritic with,plagioclase phenocrysts
The
in
a
groundmass of quartz and white mica.
Plagioclase
size
and
are
phenocrysts
quartz.
the
are aggregates of several smaller crystals
and
determinations
and
and
zoned.
Some
in
of
on zoned crystals
by
method show a variation From An3O in the
An^a along the rims.
zoned
are 1.0 to 3.0 millimeters
commonly twinned
Optical
Michel-Levy
to
phenocrysts
the
cores
The aggregates of crystals are not
resemble the lithic fragments
observed
in
the
quartz-biotite s c h i s t . Alteration of plagioclase to sericite
is
common.
foliation.
The
phenocrysts
are
often
rotated
in
the
27
The
groundmass consists of Fine
quartz,
small
Small
present.
Some
which
The
does
granoblastic
laths of white mica (muscovite?),
biotite.
kinked.
grained,
euhedral
of
only
not
the
plagioclase
crystals
laths of white mica are
retrograde mineral present
grow
and minor
in
the
plane
of
is
the
are
also
bent
and
chlorite
foliation.
Porphyrdblasts of staurolite with inclusions of quartz are a
minor p h a s e .
The high SiO52 c o n t e n t , low concentrations of FeO and M g O ,
and
low K22OiNa52O ratio (Table 5) indicate that the feldspar
porphyry
is dacitic in
suggests
that it is compositionalIy similar to trondhjemite
(after B a r k e r , 1979;
composition.
Normative
mineralogy
Figure 15).
Table 5. Major element geochemistry of metavolcanic rocks
and common igneous rocks. Data presented are weight
precent of o x i d e s .
I
510=
TiO=
Al = Ors
FeO
MnO
MgO
CaO
Na=O
K=O
Cr=Ors
LOI
K = O :Na=O
Total
1-2.
3.
4.
5.
72.9
0 .IHt
15.5
I .45
0.02
<0.5
I .67
5.4
0.84
0.02
0.93
0.16
98.87
Feldspar Porphyry (this study).
Dacite (Ewart, 1979).
Average Trondhjemite (McGregor, 1979).
Average Tonalite (LeMaitre, 1976).
2
3
4
71.9
73.3 70.99
0.29
0.49
0.14
15.5
15.4 14.28
2.1
2.36
0.94
0.10
<0.01
0.87
0.81
<0.5
2.94
3.58
1.83
5.17 4.96
5.59
1 .52
0.80
0.97
<0.01
—
1.20
0.99
0.30
0.15
0.17
99.16 99.84 100.02
5
62.6
0.74
16.8
5.57
—
2.85
5.53
3.70
2.10
—
0.56
99.89
28
An
TRONDHJEMITE
GRANITE
20
30 35
Figure 15. Normative Ab-Or-An plot of Feldspar porphyry
CaFter B a r k e r , 1979).
29
PLUTONIC ROCKS
The
central
Mountain stock.
is
part
of
the
belt
contains
the
Crevice
The contact along the margin of the
sharp and there is little alteration of the
stock
surrounding
metasedimentary units.
The rock is a weakly to non-foliated,
quartz
monzonite
with
an
biotite-muscovite
equigranular
texture.
plagioclase,
and
Biotite
muscovite comprise 5-10% of the
and
occurs
as
undulose
microcline are present in equal
large
subhedral grains
extinction.
and
is present as large perthitic crystals.
rock.
commonly
crystals.
Quartz
exhibits
Microcline
Myrmekite is common
microcline invades plagioclase grains.
and muscovite occur
amounts.
Plagioclase ( A n ^ o - occurs as large
anhedral grains and as small granular
where
Quartz,
Both
biotite
as small laths and aggregates of laths.
Muscovite commonly cuts across biotite.
The
diabase
metasedimentary
dikes.
fine-grained
The
sequence is also
Two varieties are present.
cut
several
The first is
hornbIende-plagiocIase rock that is
a
foliated.
second is a hornbIende-plagiocIase rock with very large
Cup to 3 centimeters) plagioclase phenoc r y s t s .
also
by
foliated,
but more w e a k l y .
This rock is
Similar dike rocks
throughout the Beartooth Mountains (Wooden,
1975).
occur
30
METAMORPHIC GRADE
Biotite
and
metasedimentary
grade
chlorite
package
are
present
and place the minimum
in the middle greenschist Facies.
assemblages
Assuming
throughout
The
the
metamorphic
lowest
grade
are Found in the west-central part oF the b e l t .
the presence oF primary m u s c o v i t e ,
staurolite
is
produced by the Following r e a c t i o n s :
Cl)
chlorite + muscovite =
staurolite + biotite + quartz + H 2O
CE) chlorite + muscovite + almandine =
staurolite + biotite + quartz + H 2O
The discontinuous
metamorphism
reaction
diagnostic
oF
medium
grade
in these rocks is:
chlorite + staurolite + muscovite + quartz *=•
A l 2SiOe + biotite +H2O
This
reaction breaks the staurolite-chlorite Join oF an AFM
diagram
and
permits
CThompson and Norton,
coexistence
1968; Winkler,
oF
Al2S iOe
1979)
+
biotite
CFigure 16).
31
And
+ Quartz
Figure IB.
The
Discontinuous
reaction in
CaFter Winkler, 1979).
biotite
schist
peak pressure and temperature oF metamorphism
are
qualitatively constrained by two continuous model r e actions:
Cl) chlorite + muscovite
-
staurolite + biotite + quartz + H zD
CE) staurolite + muscovite + quartz =
biotite + andalusite + HzO
These
reactions
Hoschek
garnet,
and
C1967).
have
been
Coexistence
determined
of
experimentally
s t a urolite,
by
andalusite,
and chlorite limits the peak metamorphic temperature
pressure
to
550 degrees
Celsius
and
3.0
kilo b a r s ,
32
respectively
(Figure
17).
This
suggests
a
metamorphic
thermal gradient of almost 50 degrees Celsius per kilometer.
500
600
Temperature 0C
Figure 17. Pressure and temperature of peak metamorphism.
Prograde
growth
of
metamorphism in
a
garnet
+
the biotite schist began with
quartz
+
biotite
+
plagioclase
assemblage and development of a primary Foliation (Si). This
was
Followed by growth oF porphyroblasts oF staurolite
andalusite.
chlorite,
and
accompanied
garnet
chlorite
Folding,
by
growth
oF
secondary
biotite
development oF an incipient S= surFace
rotation
porphyroblasts.
oF
staurolite,
Muscovite
aFter
and
were
andalusite,
and
andalusite
and
aFter biotite were produced by retrogression
during a later thermal event.
and
path
33
STRUCTURE
The metasedimentary rocks strike N to NE and dip
39
and
BO
Foliation
CSiD
parallel
scale
degrees to the E
and
SE.
A
strong
defined by alignment of micas is
to observed bedding CS0 D .
isoclinal
Folds CF,. D are parallel to
of
the
Folds are deformed by F= open f o l d s .
and plunge 10-50 degrees to the NE.
developed
Microscopic
The
F= Folds
in the massive quartz-rich u n i t s .
Folds
Fx
These trend
are
in less competent micaceous units and are
observed
chevron
small
regional
isoclinal Folds have strongly attenuated limbs.
isoclinal
NE
regional
generally
Axial planes
Foliation and plunge 70-80 degrees to the north.
Fi
between
well
rarely
Kink bands
are also common in the more micaceous
and
units
and are probably related to F= since the trend and plunge of
their
hingelines
cleavage
is the same.
relationships
are
along Bear Creek CCasella,
relationships
Graded
beds
evidence of
and
bedding-
overturned
et a l ., 1 9 8 2 D .
Folds
Bedding—cleavage
are only visible in the more micaceous
rocks
and are not developed in the massive u n i t s .
Structural data collected in this study is presented
Figure 18.
the
belt
These data were collected in the central part of
between Crevice Creek and Cottonwood
Figure 2D and are consistent with previous work
general
in
area CCasella et al.,
19B2D.
Creek
Csee
in the same
In the . west-central
part of the belt near Jardine CFigure 2D,
the proportion of
34
Fine
grained
becomes
micaceous
more
units
intense.
increases
and
HalIageri C1980 D
deformation
recognized
isoclinal Folds and two later sets of open Folds,
striking NUJ and the other CF3 D striking NE.
one
Fi
CF3 D
The F3 folds of
Hallager C19B0D are interpreted here as FE Folds Csee Figure
18D .
NUI
trending
open Folds CF3 D are not observed in
the
eastern part of the belt but they are known to exist in
the
Jardine area CJohn C u t h i l l ,
pens.
c o m m . D . Prior work based
on mapping in the Crevice Mountain area CFigure ED
C a v a l e r o ,■
1875D
CBrox and
also indicates F x isoclinal folds deformed
by NE trending F3 open F o l d s .
A
working
model
of the structural
on
both
previous
of
the
CBrox
and
metasedimentary
belt
Cavalero,
H a l l a g e r , 1980D and current work at Jardine
1975;
based
evolution
CJohn C u t h i l l , p e n s . c o m m .D consists of an early period of N
to
NE trending isoclinal folding CF xD followed
open Folding CF3 D . Finally,
flexure
coaxial
a gentle west-northwest trending
CF3 D warped the region.
recognized
by
The F3 open Folds are
in the eastern part of the belt perhaps
not
related
to the competent nature of the r o c k s .
The
first
isoclinal
metamorphic
deformational event Dl was characterized
Folding
mineral
porphyroblasts
accompanied
by
assemblage.
demonstrates
that
growth
of
Syn-kinematic
folding
and
the
growth
by
peak
of
prograde
metamorphism were c o e v a l . The D3 event produced F3 F o l d s , an
incipient S3 F o l i a t i o n , and retrograde mineral a s s e m b l a g e s .
35
n = 20
n= 30
n = 75
Figure 18. S t e r e o n e t s . A : Trend and plunge of hingelines of
F i isoclinal
F o l d s . B : Trend
and
plunge
of
hingelines of F2 open F o l d s . C : Strike and dip oF
regional Foliation CS0 - Si).
36
ENVIRONMENT OF DEPOSITION
The
structural history OF the
metasedimentary
package
suggests that the entire section may have been substantially
thickened and in many places overturned by isoclinal Folding
during
the Dl e v e n t .
tenuous
and
environment
requires
be
This makes stratigraphic
that
any
interpreted
models
correlation
oF
depositional
on a regional scale .„oF
gross
lithologic p a c k a g e s .
Sedimentologic
and stratigraphic evidence suggest
that
the South Snouiy Block greyuiacke Cquartz-biotite schist)
mudstone
Cbiotite
turbidity
schist)
currents.
As
were
stated
originally
earlier,
and
deposited
the
by
subarkosic
sandstone units contain up to ES percent m a t r i x . Much oF the
matrix
may
have been derived From the breakdown
rock Fragments during diagenesis C e . g .
sandstones
graded.
are
The
poorly sorted
presence
oF
Kuenen,
and commonly
graded
beds
oF
maFic
1966).
are
The
normally-
implies
rapid
deposition oF sediment From . turbulent s u s p e n s i o n . Formation
oF
graded beds by turbidity currents has been
demonstrated
in Flume experiments CKuenen and Migliorini, 1950).
Stratigraphic
turbidity currents.
evidence
also
supports
Partial Bouma sequences
deposition
CBouma,
by
1962)
preserved throughout the metasedimentary package and are
most common in the coarser grained units. A typical vertical
sequence
observed in the Field consists oF
a lower unit oF
37
massive normally graded sandstone 5 to 50 centimeters t h i c k .
The
massive
centimeter
sandstone
thick
is
layer
locally overlain by a
of
Finer
grained
I
to
3
horizontally
laminated s a n d s t o n e . Above this a ripple laminated siltstone
I to 2 centimeters thick is usually present.
sequence
is
an upper unit of siltstone or
lacks any sedimentary structures.
is
repeated
and
these repetitions
resemble
Bouma CBouma,
been
This lithologic
may
be
which
sequence
package
structural,
the ABCE and ACE sequences
1352).
deposited
current
mudstone
many times throughout the sedimentary
although
closely
Completing the
they
described
by
IF so, the massive A units would have
rapidly From suspension.
decelerated
deposition
As the
under
upper
turbidity
plane
conditions resulted in horizontally laminated s a n d .
With
bed
a
Further decrease in velocity ripples Formed in Finer grained
sediment.
Finally the suspended sediment settled out Forming
the E unit oF B o u m a .
absent.
This
velocity
with
suspended
Bouma
In many cases the B and/or C units are
can be attributed to a very rapid decrease in
only
a
massive graded
bed
load CE u n i t D being d e p o s i t e d .
seq u e n c e s ,
both
partial
and
CA
The
unit)
presence
complete,
and
oF
implies
deposition by turbidity currents.
The eastern part oF the metasedimentary belt is composed
oF
massive sandstone units with a very small proportion
mudstone
graded
or
iron Formation.
The
sandstone
and ABC Bouma sequences are locally
is
oF
commonly
preserved.
The
30
east-central
Crevice
and
part
Creek
of
the belt from
Cottonwood
CFigure 2) contains finer-grained
a higher proportion of mudstone and iron
measured
Creek
to
sandstone
formation.
section from this area is presented in Figure
A
13.
Sedimentary structures are most abundant in this part of the
outcrop
belt.
graded beds,
Bouma
sequences,
cut-and^fill
structures,
wavy b e d d i n g , cross stratification,
and rip up
clasts are common Csee Figures B - I O D . Although the sandstone
beds
are
volumetricalIy
thinner
individual
more
units
important,
and
are
they
much
occur
finer-grained.
Individual horizons of both mudstone and iron formation
much
thicker and laterally c o n t i n u o u s .
as
are
The western portion
of the belt is poorly exposed but fine-grained sandstone and
mudstone
19B0D
have been reported from Sheep Mountain
CFigure
metamorphic
2D.
grade
To
the
west
of
increases and the
Sheep
rocks
CHallager,
Mountain
become
the
highly
deformed.
In
east.
and
in
general,
This
the
sedimentary package coarsens
is accompanied by an increase in the
thickness of sandstone u n i t s .
this
distribution
of
sequences
bedding
and
rock
types,
The
lateral
presence
distributary c h a n n e l s ,
suggests
submarine f a n .
change.
that
the
abundance
A corresponding decrease
thickness and abundance of mudstone and
accompanies
to
of
iron
Formation
and
vertical
partial
and abundant
this sequence was
deposited
The general stratigraphy of the
Bouma
graded
on
a
sedimentary
33
-V ..S
Q u a r t z - b i o t i t e schist
G ra d e d bedding
Niiiiiiiim i Iiiiir
B io tit e schist
Ironstone
D ia b a s e
D a c ite p orph y ry
Q
lllllllllllliflll'
25
S1O meters
scale
Figure 13. Measured section From the central part of the
outcrop belt approximately 2.5 kilometers
southeast of Crevice L a k e .
40
package,
to
as discussed b e l o w ,
distal
This
fan environments of Walker C1979)
model
is
application
limited
facies
useful
for
purposes
of
due to incomplete areal e x p o s u r e .
diagnostic
The
(Figure
c o m p arison,
of a submarine f a n ,
in
The
along
sedimentary
the
basin.
The sediments
particular
margin
of
Deposition
an
consistent
originally
actively
subsiding
of clastic material was
Graded,
massive
sand with distributary channels and
amounts
of
and silt characterize
midfan area (Walker,
1979).
deposition
minor
in
A transition to finer
the
grained
and mud occurs between the midfan and distal f a n .
central
part of the belt contains this
Towards
the
chemically
basin
center,
precipitated
deep
transitional
water
pelagic
iron formation are most
mud
environment.
periodically
invaded
the
deeper
The
zone.
and
abundant.
Sands interbedded with muds and iron formation suggest
turbidites
by
poorly
sorted,
sand
the
were
turbidity currents along a submarine slope.
mud
is
are not recognized in the area.
following model.
deposited
but
sedimentary
observed distribution of lithologies is
the
20).
of it to this particular lithologic package
fanhead facies,
with
is consistent with the midfan
that
water
41
IDEALIZED SUBMARINE FAN
SLOPE INTO BASIN
MIDFAN
DISTAL FAN
BASIN PLAIN
(From W alker,1979)
Figure 20. Model of depositions! environment showing
location of observed sedimentary s e q u e n c e .
42
PROVENANCE
Conventional
determine
analysis
provenance
of
sandstone
composition
(Dickinson and S u z c e k 1
137SD
to
is
of
limited use when applied to metamorphic r o c k s . The Framework
mineralogy
of
diagenesis
and
major
a
greywacke
metamorphism,
identifiable
plagioclase.
as
the
components
has
been
altered
to the point where
preserved
are
the
only
quartz
and
Lithic fragments have been mostly destroyed and
consequence the proportion of matrix
Because
during
has
increased.
of these factors a different approach is
necessary
for evaluating p r o v e n a n c e .
A
more
suitable technique is the
use
of
geochemical
parameters to’ constrain the tectonic setting and composition
of
the
source
determined
major
by
area.
An approximate tectonic
setting
is
based
on
Data shown
in
the use of discriminant Functions
element geochemistry
CBhatia1
1983).
Figure 21 indicate an active continental margin setting with
some contribution From a volcanic arc; however,
fit
into
presence
also
one of the fields.
McLennan,
The
The high KpOiNa=O ratios
of plutonic rock fragments
suggest
1985;
in the
chemical
(Taylor
and
1974).
composition
of the source
approximated by interpreting the g e o c h e m i s t r y .
metagreywackes
and
meta-greywacke
a continental margin provenance
Crook,
not all data
area
can
Most of
be
the
and pelites have elevated concentrations of
43
H
2
H
0 .4
Fe2 O 3 -H M g O
WT°/.
Fe2 O 3 -H M g O
WTV.
it
h
2
0
Z'
1
O
o
O
X
Figure El. Major element composition plots of sandstones
commonly used For discrimination of tectonic
s e t t i n g . Dotted lines mark the the major Fields
oF sandstones representative oF various tectonic
settings although some points Fall outside these
Fields. Fields are: A - Oceanic Island Arc; B Continental Island Arc; C - Active Continental
M a r g i n ; D - Passive M a r g i n . Fe32O3 represents
total iron as Fe32O3 CaFter B h a t i a 1 1983) .
FeO,
MgO1
Cr,
Ni, Co, Cu,
and Zn.
REE data is less clear
but
one mudstone (Figure 13,
REE
abundance and a low La/Yb ratio CLa/Yb -
data
are
interpreted
to
sample 8536) has a low
be
the
product
2.4).
oF
total
These
maFic
or
ultramaFic rocks in the source area. H o w e v e r , not all oF the
44
samples
have
a
strong
mafic
affinity.
Some
of
metagreywackes, especially the quartz-rich samples,
the
have low
concentrations of FeD and MgD and are clearly more felsic in
composition Csee Table ID.
and plagioclase g r a i n s ,
high
SiDE
and
The abundance of detrital quartz
possible tonalitic rock
A 1 E D 3 ,and
LREE
enrichment
f r agments,
in
the
meta-
greywackes indicates a felsic source area.
The
bulk
attained
source
composition of the greywacke could have
by mixing of sediment from at least two
areas,
one
m a f ic-ultramafic
and
been
different
one
tonalitic-
trond h j e m i t i c . There are some problems with this h y p o t h e s i s .
The
metagreywackes
Na3O,
the
concentrations
of
CaOj
and K 3D . If a tonalitic-trondhjemitic rock was indeed
felsic source,
be e x p e c t e d .
be
have very low
the
unlikely
much higher CaD and NaED contents would
The low total abundance of alkalis and CaD may
result of prolonged
wea t h e r i n g ,
but
this
since some of the metagreywacke contains
seems
euhedral
doubly-terminated zircons which are magmatic in origin CPaul
Mueller,
pers. c o m m D .
45
DISCUSSION
The
South
Snowy
coppositionally
unique
Their
CaO
contents
Block
metasedimentary
in the northern
are
Wyoming
very lout Cjust
over
compared to pelites From the North Snowy Block
and
hornfels
rocks
From the Stillwater Complex
are
Province.
I
when
CMogk, 1984)
contact
aureole
CBeltrame, 1982). This low CaO content may be due to low CaO
content
in the source or perhaps weathering or hydrothermal
alteration.
, In
addition
to
low
CaO
content,
the
metasedimentary rocks have a low total abundance oF
alkalis
and
in
a
high
previously
K 22O :N a 2O r a t i o .
mentioned
Province.
Trace
Again this is unique
suites
element
From
enrichment
rocks
Cr,
Ni,
pattern.
From
Co,
northern
Wyoming
data also demonstrate the
chemical character oF these rocks.
particularly
the
Cu,
unique
The transition
and
Zn
have
the
a
metals,'
distinct
When compared to other metasedimentary
the northern Wyoming Province CFigure
22),
the
South Snowy Block rocks display an enrichment in
transition
metals
The
Archean
even at high 0 7 0 % )
suites
S iO22 concentrations.
other
From the northern Wyoming Province are
not
enriched in transition metals over such a wide range oF Si02
values.
Rocks
From the eastern Beartooth Block
enriched in Cr,
Mueller,
comparable
and Ni CMueller and Wooden,
and M o g k ,
with
geochemistry to the
in press);
respect
to
1982;
are
also
Wooden,
however these rocks are not
major
element
and
South Snowy Block m e t a g r eywackes.
REE
46
Cr ppm
1200
800 400 ■
200
-
IOO -
Cu
ppm
Co
ppm
Ni
ppm
300 -
-
ppm
120
Zn
• •••
S iO 2
WT %
Figure BE. Trace
element
variation in northern
Wyoming
Province metasedimentary r o c k s . Solid line ■
Stillwater H o r n F e l s . Dashed line - North Snowy
B l o c k . Solid circles - South Snowy B l o c k .
47
REE
patterns of South Snowy Block metagreywackes (La
“
I O O x , CLa/Yb)n=7.E - 1 2 .4D are distinctly different than North
Snowy Block metasedimentary rocks (La - S O x , (La/YbDn = 4 - 7 D
(Mogk,
1SB4;
Beartooth
Mueller et a l ., 15843,
clastic
(Mueller
et
Beartooth
rocks
al.,
rocks
(La
1984).
*=
The
but similar to eastern
IOOx,
(La/Yb)n
similarity
=
with
is coincidental since these rocks
7-15)
eastern
do
not
have comparable major element abundances and have had a very
different geologic history (Mueller et a l ,
from
other metasedimentary suites in the
1983).
REE data
northern
Wyoming
Province are n o n e x i s t e n t .
Accumulation
and
preservation
mudstone,
formation
requires an actively subsiding sedimentary b a s i n .
and original location of this
and
of
consisting
configuration
gre y w a c k e ,
sequence
sediments
The
of
of a thick
iron
basin
is
unknown but provenance data suggest that the metasedimentary
package
was
manner
Group
of
continental
westward
Eriksson
(1980).
The regional
demonstrates that rock units
that
clastic
sedimentation
towards the basin center (Figure
indicate
Cr
Fig
coarsen
is common
both
a
Tree
of
to
section,
was
prograding
53).
Provenance
a significant contribution from a
and Ni concentrations,
in
distribution
ultramafic source. The geochemical signature,
high
margin
east and at structurally higher levels in the
suggesting
data
along a
similar to the deposition of the 3,300 Ma
lithologies
the
deposited
mafic
or
especially the
in
sedimentary
40
rocks
in the upper levels of early
greenstone belts CCondie,
1981,
(3.4 - 3.0
Ga)
Archean
Taylor and McLennan,
1905).
In addition the metagreywacke is petrographicalIy similar to
greenstone
belt
sediments
Formation at South Pass,
komatiites
such
as
the
Wyoming CCondie,
Goldman
1957).
Although
and Mg-rich basalts characteristic of the
levels of early Archean greenstone belts CCondie,
not
Meadows
exposed in the South Snowy B l o c k ,
their
lower
1981) are
existence
is
inferred by the strong mafic geochemical s i g n a t u r e .
sea level
Sand
Figure 23.
Inferred configuration of the d e p ositional
setting.
Geochemical
and
petrologic evidence suggest that
metasedimentary package is
belt.
terrenes
This
are
association
this
part of early Archean greenstone
is
important
since
greenstone
not exposed anywhere in the northern
Wyoming
43
Province,
however they do exist in the central and southern
Wyoming Province CGranathl
1375;
pens.
comm.)
U-Pb dates on zircons
South
Snowy Block metagreywa'ckes suggests that they are
Preliminary
Condie1
1357;
John R a y 1
From
the
at
least as old as 3,200 Ma (Paul M u e l l e r , per. comm.).
This is
considerably
central■
Beartooth
Creek
The
older than 2,300 Ma andesites in
the
Mountains and the 2,351 Ma greenstones in the Owl
Mountains of central Wyoming (Mueller et
al,
1335).
ages of other greenstones in the Wyoming Province
have
not been determined.
The
low
metamorphic
grade,
to
geochemical
signature all suggest that the
in
belt
of
similarity
rocks
greenstone
style
sed i m e n t s ,
deformation,
and
metasedimentary
the South Snowy Block were not derived
Beartooth
Mountains.
Examination
of
unique
From
potential
the
source
terranes in the northern Wyoming Province fails to locate
a
chronologically and chemically compatible source area.
The
Fact
that these rocks are not compatible with
the
surrounding region has important tectonic i m plications.
The
Beartooth
Mountains
have experienced a long
evolution
of
continental crust which experienced a major period of growth
through
al,
continental collision around 2,800 Ma
1382,
this
Snowy
series
1334).
Andesites
collision (Mueller et a l ,
Block
of
(Mueller
were produced as a result of
1382,
1383) and the
was tectonically thickened and accreted
east verging
nappes
et
(Mogk,
1381,
1384).
North
as
a
The
50
batholithic.
complex
along
the
eastern
border
of
the
metasedimentary belt was also emplaced during this e v e n t .
Since
the
chemically
metasedimentary rocks are
incompatible w i t h ,
older
than,
the surrounding region
and
they
may have been tectonically e m p l a c e d . These rocks represent a
distinct
terrane
which has experienced a
very
different
d e positional, str u c t u r a l , and metamorphic evolution from the
surrounding
by
major
region.
It is separated from adjacent terranes
faults and therefore can be considered
to
be
a
suspect terrane similar in definition to Phanerozoic suspect
terranes
than
CJones et a l .,
the
1983) but on a much smaller
large amalgamated terranes of Alaska and
scale
British
Columbia.
The
geochemistry demonstrates that these rocks were not
derived
from
deformation
kinematic
CMogk
and
and
Henry,
prior
of
Beartooth
metamorphism
history
occurred
margin
the
Mountains.
is
The
incompatible
of the surrounding
Beartooth
in press) suggesting that the
to
Juxtaposition
the Beartooth
along
Mountains.
This
the
style
of
with
the
Mountains
Dx
southwestern
metasedimentary
sequence may be a metamorphic terrane similar in style
Phanerozoic
metamorphic
event
terranes such as the
with
Yukon-Tanana
terrane in Alaska CConey et a l , 1980).
There
is,
metasedimentary
crustal
level
however,
package
whose
another possibility.
represents
source region
Perhaps
a sample of
has
long
an
since
the
upper
been
51
eroded.
IF
represent
derived
this
is the c a s e ,
the
metasedimentary
rocks
a tectonically preserved block of rock which
From a nearby source that no
longer
was
exists.
This
hypothesis is not likely since isostatic equilibrium must be
maintained
preserve
and
it
would be impossible
to
a small piece oF the Beartooth
preFerentially
Mountains
without
preserving a comparable crustal level elsewhere.
The
northern
Wyoming Province can be divided into
general regions.
in
the
Dominantly meta-igneous rocks are
central
dominantly
and
eastern
metasupracrustal
Gallatin,
Madison,
Tobacco
Beartooth
rocks
Root
west (Wooden et a l ., in press).
belt CMogk and Henry,
between
western
approximate
(Wooden
et
the
location
metasedimentary
been
oF
al.,
present
Mountains,
present
and
in
. the
and Ruby Ranges to the
The North Snowy Block mobile
in press) roughly deFines the boundary
these two regions.
margin
,
are
two
oF
in
rocks
It has been suggested that
Beartooth
an
Archean
press).
IF
Mountains
marks
continental
so,
the
oF the South Snowy Block
the
the
margin
low
grade
may
emplaced by transcurrent Faulting during the 2,800
orogenic event.
have
Ma
Further research in the region is necessary
to validate this hypothesis.
REFERENCES
53
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U.R.. , 1979, Archean gray gneisses and the origin
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McLennan,
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P h .D •
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in:
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M o g k , D.M., Wooden, J.L., Henry, D .J ., and
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D .R ., 1984, Archean metasedimentary rocks From
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J.L., Schultz, K , and Bowes, D.R.,
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9.M.,
1972,
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57
P r i d e , D .E ., and H a g n e r , A.F., 1972,Geochemistry and origin
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McLennan,
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1982,
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SB
I
APPENDICES
APPENDIX A
ANALYTICAL METHODS
60
X R F - F U S ION WHOLE ROCK ANALYSES
Fusion
The assay pulp is dried overnight at 105 degrees Celsius
then
0.75
crucible
grams
and
of sample is
weighed
into
a
porcelain
placed in a muffle furnace for 20 minutes
350 degrees Celsius Chigh sulfide samples are first
at
BOO degrees Celsius with air blast for 20 minutes
to
ignition).
cool
is
Spectroflux
The
mixture
inserted
prior
mixed
with
ignition.
lithium
The
tetraborate
100) to bring the total weight to
placed in a 2p cc Pt-5%
ignited
Au
5.00
CJMC
grams.
crucible
and
into a muffle furnace at 1200 degrees Celsius
for
25 minutes.
during
then
is
roasted
The sample is then placed in a dessicator to
prior to weighing for loss on
sample
at
The crucibles are swirled three different times
this period to mix the melt prior to pouring into 30
mm Pt-5% Au moulds. The resulting disks are removed from the
moulds and are ready for presenting to the X R F .
BI
XRF Measurements
A
Philips
model PW1220 XRF unit is used
For
all
the
measurements made under the Following c o n d i t i o n s :
ELEMENT
Na
Mg
Al
Si
K
Ca
Ti
Cr
Mn
Fe
Co
Ni
TUBE
TARGET
Kv/Ma
COUNTER
COLLIMATOR
Cr
BO/32
Flow
Coarse
CRYSTAL
TlAP
TIME
CsecD
BO
PET
Fine
LIFlOO
20
F&S
W
Cr
Ul
Cr
>>
Scint
FSS
Coarse
Fine
Coarse
Background measurements are made For Na Mg,
Al, Ti, Co, and
Ni using the same conditions as the e l e m e n t s .
BE
Standards
Calibration of the XRF system was done using a group
of
i
approximately
75
International ReFerence Samples
organizations
in
S countries consisting oF such groups
C C R M P , USES,
F r o m . 13
as
N B S , and N I M . Listed in the table below are the
ranges covered by the standards and the relative accuracy oF
XRF values produced For the major elements.
RANGE
ELEMENT
OVERALL RELATIVE DEVIATION*
(%)
NaiaO
0.5 to 10
4.40
MgO
0.5 to 50
3.67
A I 3O 3
0.5 to 70
2.37
to 34
1.32
CaO
0.1 to 85
3.33
K=O
0.1 to 15
2.16
Fe
0.1 to 67
I .72
SiO=
I
*0VERALL RELATIVE DEVIATION
ZCREL . DEV-D2
CN - ID
63
Accuracy
Tc Further demonstrate the relative accuracy of the
analysis,
’’u s a b l e ”
XRF
the' Following table compares the ’’recommended” or
values For the standards to those produced by
the
XRF.
GSP -I
ABU-1
BR
ELEMENT
USABLE
VALUE
XRF
USABLE
VALUE
XRF
%Na=0
4.32
4.55
%MgO
1.52
1,53 ■ 13.4
13.0
3,07
3.13
USABLE
VALUE
XRF
2.81
2.98
0.87
0.83
^ Al2O 3
17.2
17.0
. 10.3
10.1
15.3
15.0
%SiO=
59.6
59.5
38.4
38.5
67.3
67.5
%K=0
2.32
'2.97
%CaO
4.94
4.80
%Fe
4.74
4.82
1.41
13.8
9.02
1.34
13.4
9.08
NIM -DUSABLE
VALUE XRF
0.37
25.3
4.18
51.1
<0.5
25.2
4.34
50.8
5.51
5.55
0.08
<0.1
2.03
2.00
2.66
2.61
3.00
3.00
8.82
8.73
64
Precision
The
following
precision
of the XRF method is illustrated in
table showing the means and
standard
the
deviations
for the major elements measured on 36 different disks of the
same sample run at different times.
ELEMENT
MEAN
S.D.
%Na=0
2.72
0.11
%MgO
6.51
0.12
%A1=0=
17.6
0.15
■'■SiD 22
53.3
0.27
SiK52O
1.00
0.01
SiCaO
7.77
0.03
%Fe
5.26
0.02
65
ICP ANALYSES
In addition to the XRF-Fusion analyses,
analysed
For
30 elements by ICP.
The
97 samples were
methodology
is
as
Follows:
First,
tube
500 mg oF sample is weighed and transFerred to a test
then
E mis oF aqua regia is added and the mixture
is
heated in a water bath For GO minutes at 95 degrees Celsius.
AFter digestion the mixture is diluted to 10 mis with dilute
HCL.
The
nebulizer
sample
then
aspirated
through
determined by the emission spectrograph oF the ARL 3500
ICP
instrument
is
calibrated
The
standard
are
This
an argon plasma s t r e a m .
a
elements
unit.
into
is
using
standard
s o l u t i o n s . Quality control is done by periodically inserting
USGS standard samples in each b a t c h .
v
GE
APPENDIX B
DATA •
ry
Table B . Modal analyses of m e t a g r e y w a c k e .
Safiple No.
# of points
8531
8542 8550 8553 8590 8591 8556 8563 8572 8573 8578 8559 8561 8567 8580 8575 8576 8545 8544 8554
460
580
440
19
42
34
56
302 292 287 264
49
53
41
64
(29) (26) (31) (28)
87 109
81 104
90
4
11
I
5
2
4
6
6
2
8
5
4
3
I
2
I
2
3
11
350
48
22
271
37
440
520
480
480
38
250
48
CRrO
Biotite*
Chl orite
Garnet
Staurolite
Tourmaline
Opaque
-
139
27
4
I
"
440
440
440
520
480
44
65
18
38
34
264 266 240 292 294
39
80
46
42
48
(28) (31) (30) (24) (22)
98
97 117
83
89
103
3
2
5
2
3
I
6
4
2
—
—
Z
2
I
440
430
440
400
24
35
261 245
47
36
- (27)
115 104
6
2
27
253
47
43
261
32
94
6
i
2
102
54
21
34
17
212 234 246 262
32
53
32
64
- (25) (22) (24)
97 123 125 117
5
3
2
5
I
”
I
~
440
I
I
“
“
2
I
2
"
440
440
460
NODES
Qp
Qn
F
11
74
14
13
72
15
9
80
11
11
76
13
6
79
16
3
86
12
7
82
11
10
76
14
ii
77
12
5
71
24
16
72
11
12
78
10
7
81
11
ii
75
14
8
77
14
13
78
10
18
71
11
7
76
17
11
79
10
5
76
19
Framework
24
76
19
BI
24
76
21
79
27
73
29
71
25
75
21
79
21
79
23
77
23
78
21
79
27
73
26
74
24
76
24
76
26
75
30
70
29
71
25
75
68
Table 7. Rare
Earth and trace element data For South
Snowy
Block metasedimentary rocks.
All concentrations in
ppm.
Element
Sm
Eu
Lu
Ba
U
Th
Yb
Nd
Na
La
Ce
Tb
Cr
HF
Sr
Zr
Cs
Sc
Rb
Fe
Zn
Ta
Co
8524
110235
8530
8536
8544
.8563
4.15
2.95
1.45
4.47
1.53
0.37
0.73
I .07
0.62
I .17
0.44
0.32
0.26
0.27
0.22
0.29
0.22
O .10
670.00
423.00
160.00
1210.00
122.00
177.00
---8.24
3.28
1.32
4.40
2.16
11.59
8.62
3.95
8.92
4.00
2.13
1.85
1.84
1.53
1.97
1.54
0.71
——— —
—'—-20.12
16.99
20.60
269.00 17760.00 18080.00
3070.00 22930.00
3461.00
31.38
18.92
6.18
28.86
7.00
3.17
57. SB
37.91
12.56
55.17
15.81
6.97
0.47
0.44
0.42
0.85
0.36
0.20
309.00
217.00
204.00
366.00
170.00
131.00
5.02
3.66
1.44
3.20
1.66
0.73
—
————
—
—--122.00
213.00
--——
---—
198.00
130.00
150.00
—--—
8.12
3.49
8.33
0.23
0.21
12.26
12.01
10.86
24.99
15.75
5.79
80.83
72.46
7.46
124.00
11.29
18.98
24890.00 145950.00 83140.00 184240.00 40300.00 47900.00
81.04
113.00
74.62
108.00
80.78
33.80
0.78
0.63
0.33
0.62
0.35
0.17
16.06
14.49
8.70
26.08
10.35
6.41
8524
- Magnetite Iron Formation
110235 - Silicate Iron Formation
8530
- Biotite Schist
8536
- Bictite Schist
8544
- Quartz-biotite Schist
8563
- Quartzite Metacomglomerate
—
Table 8. ICP geochemical data.
Mo
Rock fype Sample No. ppm
Cu
ppm
Pb
ppm
Zn
ppm
Hg
ppm
Ni
ppm
Co
ppm
Mn
ppm
Hs
ppm
U
ppm
Th
ppm
Sr
ppm
Cd
ppm
Sb
ppm
Bi
ppm
V
ppm
BS
BS
BS
BS
BS
8514
8526
8528
8530
8536
1.7
5.7
5.2
1.8
7.1
37
86
4.3
11
24
5
16
6
5
5
90
66
47
100
12
0.5
0.5
0.5
0.5
0.5
120
98
94
210
6
23
26
17
33
2
540
120
250
550
440
3
48
4
2
2
ND
ND
NO
ND
ND
ND
ND
ND
ND
MD
MO
MD
MD
MD
MO
0.3
0.6
0.3
0.5
0.3
10
10
10
10
10
3
2
2
2
2
67
80
81
160
18
CGL
CGL
CGL
8564
8565
8587
8
8
8
63
89
69
14
7
15
57
53
61
0.2
0.1
0.2
47
33
88
14
13
18
433
291
393
14
10
2
5
5
5
10
7
11
5
8
5
I
I
I
4
2
2
8
4
2
53
36
52
DB
DB
DB
DB
8512
8516
8517
8568
1.8
2.2
2.8
2
82
34
53
84
5
5
8
3
36
50
16
24
0.5
0.5
0.5
0.1
31
24
40
30
13
16
16
13
310
390
330
193
2
2
2
12
ND
ND
NO
5
ND
ND
NO
I
NO
MO
MD
41
0.3
0.4
0.5
I
10
10
10
2
2
2
2
3
75
87
66
66
FMV
FMV
FMV
FMV
FMV
FMV
FMV
FMV
FMV
FMV
8504
8520
8525
8527
8532
8538
8541
8548
8577
8584
5.3
3.5
1.5
3.8
1.8
1.5
5.1
6
4
5
25
17
4.3
6.3
5.3
27
11
57
18
5
5
12
10
8
13
7
16
7
9
17
16
25
20
33
31
11
47
5
16
3
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.2
0.1
0.1
6
6
3
5
8
10
5
4
4
I
2
3
I
2
3
3
3
2
2
I
90
120
100
86
HO
77
87
23
64
65
81
4
2
2
3
4
4
9237
2
3
ND
ND
ND
ND
ND
ND
ND
5
5
5
ND
NO
NO
ND
ND
ND
NO
9
2
6
NO
ND
MD
ND
ND
ND
ND
9
14
3
0.3
0.3
0.3
0.4
0.3
0.3
0.4
I
I
I
10
10
10
10
10
10
10
3
2
2
2
2
2
2
3
2
2
3
3
14
6.3
7.9
6.7
14
6.3
5.9
7.7
3
5
I
GBCS
GBCS
GBCS
8548
8502
8570
6
8.2
6
11
24
16
24
5
11
93
60
152
0.2
0.5
0.1
126
86
112
21
15
15
532
410
404
1123
340
86
5
NO
5
11
NO
10
5
ND
2
I
0.3
I
2
10
2
2
2
2
123
64
82
GR
GR
GR
8508
8513
8533
7.4
5.5
5.1
3.1
10
2.8
13
19
14
26
28
42
0.5
0.5
0.6
9
3
13
3
I
5
200
69
280
33
2
4
ND
ND
NO
ND
ND
NO
ND
NO
ND
0.3
0.3
0.3
10
10
10
2
2
2
7
10
16
QBSFG
QBSFG
QBSFG
OBSFG
QBSFG
8507
8518
8535
8562
8585
1.8
2
3.2
4
7
2.9
5.7
19
84
21
5
7
6
13
15
85
19
34
109
16
0.5
0.6
0.5
0.1
0.1
150
150
160
178
89
27
28
27
29
16
370
580
250
670
328
83
4
13
27
2
ND
ND
ND
5
5
ND
ND
ND
13
8
NO
ND
ND
6
5
0.7
0.5
0.5
I
I
10
10
10
5
2
3
4
2
6
2
160
100
150
92
83
8501
8506
8508
8511
2.4
7.7
0.5
4.3
21
14
120
9.1
5
6
5
5
14
29
34
24
0.5
0.5
0.5
0.5
13
36
25
25
2
6
12
4
220
760
300
330
23
45
52
3
ND
ND
ND
NO
ND
ND
ND
NO
MD
ND
NO
NO
0.5
0.7
0.4
0.4
10
10
10
10
2
4
2
2
34
31
65
36
IF
IF
IF
IF
m
CD
Table 8.
continued
Ho
Rock Type Sanple No. ppn
Cu
ppn
Pb
ppn
Zn
ppn
Rq
ppn
Ni
ppn
Mn
ppn
Co
ppn
Hs
ppn
U
ppn
Th
ppn
Sr
ppn
Cd
ppn
Sb
ppn
Bi
ppn
V
ppn
IF
IF
IF
IF
IF
IF
IF
8519
8523
8524
8529
8537
8552
8571
3.3
2.5
1.5
5.9
1.2
7
4
18
15
12
57
27
180
11
7
5
6
6
5
2
7
11
14
15
34
42
38
29
0.8
0.5
0.6
0.7
0.5
0.3
0.1
15
22
24
57
170
74
11
4
5
6
11
29
15
3
140
210
300
330
460
493
541
7
5
7
5
58
1852
3
NO
NO
NO
NO
NO
5
5
ND
ND
NO
ND
NO
7
5
NO
MD
ND
NO
ND
6
5
0.4
1.1
0.8
0.4
0.7
I
I
10
10
10
10
10
2
3
4
3
5
3
3
2
3
23
45
40
40
130
14
16
NP
NP
8505
8566
9.1
5
6.5
14
14
15
22
28
0.5
0.1
5
7
2
2
190
174
120
4
ND
5
MD
2
ND
15
0.3
I
10
2
2
2
8
8
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
OBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
OBS
OBS
QBS
QBS
QBS
QBS
QBS
OBS
QBS
8503
8510
8521
8522
8531
8534
8539
8542
8543
8544
8545
8547
8550
8551
8553
8557
8559
8560
8567
8569
8572
8573
8574
8575
8576
8579
8580
8582
8583
8586
8588
8589
8590
9.7
3.1
3.4
6
1.3
2.7
6.1
4
5
4
3
6
3
3
6
3
7
I
6
7
7
7
6
5
7
6
9
7
7
7
7
6
8
73
28
2
55
47
65
56
41
49
33
69
58
38
91
23
15
41
19
18
90
40
52
54
33
58
20
33
39
32
24
57
80
44
5
5
7
10
6
5
6
13
16
9
13
8
12
15
17
5
16
9
12
11
11
11
9
13
8
8
9
19
15
13
16
12
10
39
70
100
79
80
97
50
67
71
78
30
77
30
12
29
31
55
39
68
78
72
65
67
12
76
72
54
63
65
27
73
20
72
0.5
0.5
0.5
0.5
0.8
0.5
0.5
0.1
0.1
0.2
0.2
0.4
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.1
0.1
0.1
0.2
0.1
0.1
0.2
94
130
180
90
120
120
44
59
85
69
125
50
80
66
53
11
38
131
58
52
49
72
85
102
69
61
30
51
44
64
97
76
55
18
17
32
19
25
25
14
12
14
16
20
9
14
9
12
3
11
22
8
16
12
16
18
17
17
14
9
13
11
11
18
17
13
330
370
280
450
450
760
220
514
430
582
405
597
176
132
418
120
439
510
713
358
212
305
325
312
353
372
438
527
505
333
324
420
353
91
6
97
34
2
2
2
93
69
27
37
82
122
63
37
9
16
19
118
20
11
10
11
16
9
4
2
5
2
2
9
5
8
NO
ND
NO
ND
NO
MO
NO
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
NO
NO
NO
ND
MD
ND
ND
11
14
13
9
11
8
10
9
3
14
7
11
15
9
9
8
8
12
11
9
9
10
9
10
8
10
ND
ND
ND
ND
ND
MD
MD
7
7
8
7
9
6
166
7
18
28
6
7
10
7
7
8
6
8
7
6
3
9
6
8
5
10
0.3
0.3
0.6
0.3
0.4
0.3
0.3
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
10
10
10
10
10
10
10
2
2
2
2
2
2
2
2
2
2
2
2
4
2
3
2
2
2
2
3
2
4
2
2
2
2
3
2
2
2
2
2
2
4
2
2
2
2
2
2
2
2
2
2
6
5
4
4
4
2
4
2
2
2
2
2
2
2
2
79
76
150
80
93
120
79
75
70
80
107
54
102
17
63
13
46
93
56
74
55
48
52
82
56
61
51
42
52
61
62
65
68
Table 8. — continued
Cu
ppn
Mo
Rock Type Sanple Mo. ppn
Pb
ppn
Zn
ppn
Hg
ppn
Ni
ppn
Co
ppn
Mn
ppn
LI
ppn
Hs
ppn
Th
ppn
Sr
ppn
Cd
ppn
Sb
ppn
V
ppn
Bi
ppn
QBS
8591
7
25
12
73
0.1
54
14
393
2
5
10
5
I
3
2
67
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
8515
8554
8555
8556
8558
8561
8563
8578
8581
8
6
4
6
5
5
6
8
9
39
76
58
46
31
49
128
18
50
13
11
10
7
19
6
10
10
14
16
57
69
62
68
33
80
59
74
0.9
0.2
0.1
0.1
0.2
0.2
0.1
0.1
0.1
49
54
69
58
57
138
77
43
59
9
13
15
14
13
20
21
9
15
650
253
507
378
600
516
410
558
693
32
26
12
18
17
66
18
14
2
ND
5
5
5
5
5
5
5
5
NO
13
13
9
11
8
11
8
20
ND
6
5
8
8
5
8
7
9
0.6
I
I
I
I
I
I
I
I
10
2
2
2
2
6
6
2
2
4
4
5
3
2
13
6
2
2
49
64
48
61
67
82
68
45
48
4.3
7.1
3.6
5.5
6.3
8.0
3.8
3.7
2.3
6.0
7.1
34.5
17.0
26.5
44.2
55.0
73.7
17.6
44.0
63.3
5.3
10.3
0.5 105.6
0.3 108.0
0.4 145.4
0.2 75.1
0.2 67.1
0.2 56.0
5.2
0.4
0.5 42.9
0.4 31.3
8.3
0.5
6.0
0.3
20.2
17.0
25.4
15.2
14.3
15.0
2.2
8.8
14.5
3.0
2.0
380.0 11.8
448.7 516.3
439.6 25.8
394.9 30.6
507.2 22.8
8.7
372.3
82.2 16.8
371.3 187.3
305.8
4.5
183.0 13.0
182.0 62.0
0.0
3.3
2.0
4.0
4.4
5.0
1.5
0.9
1.3
0.0
2.5
0.0
7.0
4.2
7.9
10.3
9.3
1.7
1.1
0.3
0.0
1.0
0.0
2.3
2.2
11.2
6.2
6.0
2.6
1.0
10.3
0.0
7.5
0.4
0.8
0.7
0.9
1.0
1.0
0.5
0.7
0.6
0.3
0.7
10.0
4.7
7.4
3.9
3.8
2.7
7.7
8.6
8.0
10.0
6.0
AVERAGE COMPOSITIONS
BI0TITE SCHIST
GAR-BI0-CHL SCHIST
FINE GRAINED QBS
QUARTZ-BIOTITE SCHIST
COARSE GRAINED QBS
CONGLOMERATE
METAVOLCANIC
IRON FORMATION
DIABASE
GRANI TE
MONZONITE PORVPHRV
7.4 63.0
13.3 101.7
9.2 52.6
10.8 58.6
11.1 57.6
12.0 57.0
10.4 20.7
5.4 25.8
5.3 31.5
15.3 32.0
14.5 25.0
2.2 81.2
2.0 89.7
3.4 117.0
2.5 69.1
4.6 59.1
4.7 47.0
6.4
3.5
3.0 43.1
2.3 73.5
2.0 11.0
8.0
2.0
i-*
I1
Rock Type Sanpl
*
Table 0. - continued
La
ppn
Cr
ppn
Ba
ppn
Ti
%
M
ppn
B
ppn
Al
%
Fe
%
Mg
%
Na
%
Ca
8
K
%
P
%
BS
BS
BS
BS
BS
8514
8526
8528
8530
8536
ND
ND
ND
ND
ND
220
470
410
450
130
120
92
200
920
32
2
3
3
2
I
3
2
2
3
2
0.099
0.034
0.11
0.29
0.041
3.7
3.4
1.6
4
1.2
5.5
4.5
4.2
8.4
3.6
2.4
2
1.7
3.3
0.18
NO 0.054 0.91 0.027
ND
I 0.11 0.11
ND 0.23 0.94 0.035
ND 0. 19
2.8 0.03
ND 0. 19 0.039 0.021
CGL
CGL
CGL
8564
8565
858?
13
10
11
277
205
283
46
21
59
4
2
2
I
I
I
0.04
0.03
0.12
1.73
1.15
1.75
3.44
2.67
3.8
1.39
0.88
1.49
0.02
0.01
0.03
0.1
0.21
0.24
DB
DB
DB
DB
8512
8516
8517
8568
ND
NO
ND
5
70
49
92
59
94
100
79
62
3
3
3
2
3
2
2
I
0.16
0.17
0.14
0.09
2.7
1.8
2.4
2.11
3
3.6
3.1
1.77
0.95
0.94
1.1
0.45
ND
ND
NO
0.34
0.3 0.051
2
1.6 0.25 0.069
1.6 0.094 0.033
1.47 0.11 0.05
FMV
FMV
FMV
FMV
FMV
FMV
FMV
FMV
FMV
FMV
8504
8520
8525
8527
8532
8538
8541
8548
8577
8584
ND
ND
ND
NO
ND
ND
ND
10
3
3
83
62
49
64
78
70
76
82
53
51
75
92
65
190
150
96
53
25
46
14
I
I
I
I
I
I
2
4
2
3
2
2
2
2
2
2
2
I
I
I
0.009
0.007
0.017
0.035
0.006
0.008
0.003
0.01
0.01
0.01
0.72
0.56
0.38
0.53
0.41
0.55
0.35
0.27
0.42
0.25
0.74
0.2
0.83 0.25
0.94 0.14
0.91 0.25
0.76 0.098
0.91 0.16
0.71 0.046
1.1 0.02
0.61 0.17
0.19 0.02
GBCS
GBCS
GBCS
8549
8502
8570
41
ND
10
347
280
222
677
160
162
2
I
2
I
7
I
0.37
0.062
0.09
5.09
3.6
3.33
8.31
7
7.19
GR
GR
GR
8508
8513
8533
ND
ND
ND
HO
86
100
89
63
58
2
2
2
2
2
2
0.021
0.027
0.076
0.74
0.5
0.98
QBSFG
QBSFG
OBSFG
QBSFG
OBSFG
8507
8516
6535
8562
8585
ND
ND
ND
26
11
360
270
350
361
242
380
200
730
377
500
2
2
2
3
2
8
3
3
I
I
0.2
0.15
0.3
0.24
0.26
IF
IF
IF
IF
8501
8506
8509
8511
ND
NO
ND
ND
99
180
56
no
100
86
190
32
2
2
2
2
2
4
4
3
0.044
0.082
0.12
0.049
0.16
0.09
0.16
0.03
0.03
0.03
0.015
0.009
0.011
0.014
0.029
0.011
0.027
0.01
0.01
0.01
2.79
2
1.85
0.06
NO
0.01
0.16
0.23
0.14
2.67
0.4
0.43
0.05
0.03
0.04
1.2
0.7
1.7
0.13
0.15
0.39
NO
ND
NO
0. 14
0.1
0. 16
0.41 0.049
0.24 0.021
0.71 0.043
5.2
4.7
5
3.98
3.17
9.8
7.8
7.1
6.59
5.23
2.7
2.8
2.7
2.96
1.94
ND
0.8
ND 0.097
ND 0.076
0.03
0.1
0.06 0.06
1.5 0.025
1.3 0.028
2.7 0.036
1.55 0.05
1.62 0.03
1.6
2
5.6
2.2
8.6
5.7
2.7
5.5
0.29
0.57
0.79
0.48
ND
ND
ND
ND
2
0.21
0.11
0.2
0.26
0.15
0.11
0.12
0.17
0.1
0.12
O
ND 0.046
ND 0. 13
ND
ND 0.16
ND 0.08?
ND 0.04
ND 0.065
0.01 0.01
0.05 0.03
0.03 0.03
1.4
1.1
4.1
1.5
0.18
0.51
0.12
0.14
0.042
0.026
0.051
0.031
Table 6. - continued
La
Rock Type Sample No. ppm
Cr
ppm
Ba
ppm
H
ppm
B
ppm
Ti
K
Al
K
Fe
%
Mg
%
Na
%
Ca
%
K
%
P
K
IF
IF
IF
IF
IF
IF
IF
8519
8523
8524
8529
853?
8552
85? I
NO
NO
ND
ND
ND
20
7
83
120
150
190
320
109
80
82
55
90
32
360
9
14
I
I
I
6
3
2
3
2
2
2
2
2
138
10
0.03?
0.047
0.044
0.03
0.23
0.03
0.03
1.1
1.1
0.94
1.9
4.7
1.28
0.99
4.1
19
19
3.7
b .8
3.68
3.35
0.25
0.42
0.39
1.2
2.8
0.35
0.23
ND
1.1 0.081 0.036
NO 0.82 0.084 0.017
ND 0.83 0.055 0.022
NO
1.5 0.12 0.045
ND 0.096
2 0.037
0.08 0.76 0.04 0.04
0.09 0.89 0.04 0.04
NP
NP
8505
8566
NO
5
130
77
51
70
I
4
2
I
0.007
0.02
0.61
0.47
0.95
0.78
0.22
0.23
ND 0.093
0.07 0.08
0.13 0.015
0.16 0.03
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
QBS
OBS
QBS
QBS
QBS
QBS
8503
8510
8521
8522
8531
8534
8539
8542
8543
8544
8545
8547
8550
8551
8553
8557
8559
8560
8567
8569
8572
8573
8574
8575
8576
8579
8580
8582
8583
8586
8588
8589
8590
ND
NO
ND
ND
ND
ND
ND
33
32
33
30
24
32
21
27
7
28
30
24
27
19
23
17
16
23
26
20
8
14
11
21
13
11
380
270
320
310
400
390
320
292
293
249
256
263
248
130
247
71
260
222
248
332
256
234
234
259
283
267
270
245
280
263
298
276
306
470
470
HO
400
540
240
210
478
267
326
614
187
489
70
334
216
227
282
401
177
206
219
222
726
144
331
160
235
207
337
264
I
I
4
I
2
I
I
2
2
2
3
4
2
4
4
3
2
2
4
3
2
2
2
2
2
2
2
2
8
3
3
2
2
6
5
2
2
2
2
2
I
I
I
I
I
I
I
I
I
I
I
I
3
I
I
I
I
I
I
I
I
I
I
I
I
I
0.2
0.18
0.047
0.17
0.24
0.16
0.12
0.22
0.2
0.19
0.24
0.21
0.32
0.04
0.22
0.05
0.16
0.22
0.2
0.15
0.15
0.12
0.11
0.23
0.14
0.21
0.13
0.11
0.1
0.19
0.15
0.18
0.15
3.3
3.5
2.7
2.9
2.6
4.1
2.6
2.6
2.79
2.78
3.72
2.51
4.63
4.47
2.87
0.68
2.28
4.07
1.88
2.35
1.75
1.83
2
2.95
1.94
2.3
1.34
2.06
1.91
2.05
1.96
2.57
1.9
5
5.5
9
4.9
4.5
6
4.1
3.48
3.87
4.07
4.65
3.26
9.82
0.94
3.85
0.93
3.17
6.02
3.02
3.91
2.98
3.11
3.46
4.44
3.47
3.66
2.23
3.95
3.42
3.37
3.69
4.21
3.47
1.8
1.9
2.4
1.8
1.7
2.7
1.5
1.46
1.72
1.6
2.21
1.56
2.25
0.17
1.45
0.26
1.16
2.11
1.13
1.47
1.12
1.28
1.48
1.98
1.39
1.38
0.86
1.41
1.3
1.28
1.46
1.72
1.43
ND
ND
ND
ND
ND
ND
ND
0.07
0.05
0.05
0.09
0.06
0.06
0.41
0.07
0.09
0.11
0.05
0.04
0.04
0.04
0.03
0.03
0.05
0.03
0.05
0.04
0.02
0.03
0.05
0.05
0.05
0.05
1.9
1.5
0.37
1.6
1.9
1.5
I
1.43
1.25
1.09
1.71
1.41
2.09
0.09
1.28
0.27
0.81
1.45
1.1
0.81
0.78
0.74
0.71
1.33
0.63
1.32
0.77
0.76
0.69
1.07
0.96
1.09
1.01
0.08
0.055
0.44
0.068
0.094
0.074
0.051
0.06
0.06
0.08
0.0?
0.06
0.05
2.77
0.05
0.07
0.22
0.06
0.1
0.04
0.06
0.15
0.22
0.05
0.12
0.07
0.04
0.06
0.06
0.05
0.11
0.06
0.07
0.023
0.024
0.039
0.022
0.029
0.031
0.021
0.03
0.03
0.04
0.03
0.03
0.04
0.03
0.03
0.02
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.02
0.03
0.02
0.02
0.03
0.03
0.02
0.03
0.03
0.02
Table B
La
PPri
Cr
ppn
Ba
ppn
OBS
8591
15
316
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
QBSCG
8515
8554
8555
8556
8558
8561
8563
8578
8581
ND
29
27
23
21
21
21
23
16
230
281
209
234
256
309
340
242
384
34
492
256
541
426
342
365
254
474
r\)H *^ j_ L r\)i\> u j.L rv
•I
S
Rock Iype Sanpl
continued
0.0
17.0
7.4
17.2
20.1
11.3
1.6
2.5
1.3
0.0
2.5
336.0
283.0
316.6
273.2
276.1
255.0
66.8
136.1
67.5
98.7
103.5
272.8
333.0
437.4
308.4
353.8
42.0
80.6
95.5
83.8
70.0
60.5
2.2
1.7
2.2
2.5
3.0
2.7
1.7
2.3
2.8
2.0
2.5
Ti
K
Al
Ti
Fe
Ti
Mg
Ti
Na
K
Ca
K
K
Ti
P
Ti
0.19
2.13
3.75
1.49
0.04
0.04
1.06
0.03
0.038
0.22
0.21
0.21
0.21
0.18
0.2
0.18
0.2
2
2.34
2.31
2.12
2.35
2.88
2.44
1.59
2.21
2.9
3.29
3.46
3.06
3.31
4.71
4.51
2.47
4.2
1.1
1.14
1.25
1.1
1.27
2.12
1.74
0.96
1.42
ND
0.06
0.04
0.05
0.05
0.04
0.03
0.05
0.04
0.51
0.06
0.06
0.07
0.05
0.07
0.09
0.05
0.11
0.13
1.2
1.29
1.16
1.31
1.02
1.05
0.92
1.29
0.04
0.02
0.03
0.03
0.03
0.03
0.03
0.05
0.03
0.115
0.174
0.230
0.168
0.183
0.063
0.012
0.068
0.140
0.041
0.014
2.780
4.007
4.410
2.589
2.249
1.543
0.444
2.128
2.253
0.740
0.540
5.240
7.500
7.304
4.094
3.546
3.303
0.770
7.466
2.868
1.200
0.865
1.916
2.213
2.620
1.527
1.344
1.253
0.135
0.706
0.860
0.223
0.225
0.000
0.023
0.018
0.051
0.040
0.020
0.009
0.015
0.085
0.000
0.035
0.333
0.183
0.227
0.168
0.119
0.183
0.065
1.281
1.668
0.133
0.087
0.960
1.167
1.734
1.102
1.041
0.137
0.155
0.306
0.189
0.453
0.145
0.045
0.040
0.034
0.028
0.032
0.030
0.015
0.035
0.051
0.038
0.023
AVERAGE COMPOSITIONS
BIOnFE SCHIST
GAR-BIO-CHL SCHIST
FINE GRAINED QBS
QUARTZ-BIOTITE SCHIST
COARSE GRAINED QBS
CONGLOMERATE
METAVOLCAMIC
IRON FORMATION
DIABASE
GRANITE
MONZONITE PORYPHRY
2.4
3.0
3.2
1.5
1.1
1.0
1.7
15.5
2.0
2.0
1.5
MONTANA STATE UNIVERSITY LIBRARIES
762 10000902 4
N378
Tli27 5
cop. 2