leaflocalityfromlowerKirtland
NewLateCretaceous
Bistiarea,SanJuanBasin,NewMexico
member,
Shale
and
Assistant,
Hunf, Research
ol LandManagement,
Albuquerque,andAdrian
byCotemanR. Robison,U.S.Bureau
Resources
of MinesandMineral
NewMexicoBureau
Donald L. Wolberg,Paleontologist,
This preliminary report represents the first substantial paleobotanic study of new Fruitland or Kirtland plant fossils in more than 65 yrs. The florule is
the most diverse one ever found in either the Fruir
land or Kirtland, and it adds substantially to the list
of taxa known from these formations. The Fruitland
and Kirtland floras need more paleobotanic study;
cooperation from the coal companies in the area will
make this possible. More precise stratigraphic delineation of floras is needed in differentiatine the two
formations.
The area in and around Hunter Wash. near
the site of the Bisti Trading Post, in westcentral San Juan Basin, has been actively investigated by geologists and paleontologists
for almost 70 yrs (for example, Bauer, l9l7;
Bauer and Reeside, 1921; Gilmore, l9l7;
Clemons, 1973; Hutchinson, 1981). Within
the immediate region, rocks of the Lewis Shale
(Late Cretaceous), Pictured Cliffs Sandstone,
Fruitland Formation, and Kirtland Shale are
exposed (table l). The Bisti-Fruitland coal
field, upon which this area lies, is estimated to
contain 1.870 million metric tons of subbituminous. low-sulfur coal beneath less than 250
ft of overburden and is the greatest undeveloped reserve in the San Juan Basin (Shomaker, l97l). To better understand the stratigraphic record and depositional environments
of the rocks containing these resources, detailed field investigations were made near the
old Bisti Trading Post (Fig. l). These involved
stratigraphic sedimentologic and paleontological studies (Hunt and others, 1981). During
the course of these investigations a new leaf
locality was found in the Fruitland-Kirtland
sequence.
TABLE l-Uppen Cnpracrous (CavpaNraN ro
oF
MeestntcHtreN)srRATtcRApHtc
uNtrsINAREA
HuNrpnWasn.
Stratigraphicunit
Ojo Alamo Sandstone
Naashoibito Member
Upper shale member
Kirtland Shale
Farmington Sandstone
Member
Lower shale rnember
Fruitland Formation
Pictured Cliffs Sandstone
Lewis Shale
Thickness
20 rn
20m
30m nonmarine
120m
250m
50m
25 m final marine
from
20m regression
SanJuanBasin
Geologic background
The Upper Cretaceous
rocksof the Western
Interior were depositedin or near an epeiric
seathat extendedfrom the Gull of Mexico to
the Arctic Ocean.This seaway,approximately
3,000 mi in length and 1,000 mi in width,
divided the North American landmassinto
August1982
New Mexico Geology
Rt3W Rl2W Rllw
Rlow
Rgw
FIGURE 1-Gnorocrcet- MAp oF AREArN vrcrNrry oF LEAFLocALITY.Also shown is Fossil Forest, a fossiliferous area currently being studied by the authors and others. Klmv, Lewis Shale; Kpc, Pictured Cliffs Sandston€; Kf, Fruitland Formation; Kk, Kirtland Shale; Kkl, lower shale member of Kirtland Shale; Kkf,
Farmington Sandstone Member of Kirtland Shale; TKoa, Ojo.Alamo Sandstone; Tn, Nacimiento Formation; Tsj, San Jose Formation.
two large continentalareas. The San Juan
Basinlay on the westernmarginof the seaway
and was intermittently inundated by the advancesand retreatsof the sea (Fassettand
Hinds,l97l).
The Pictured Cliffs Sandstonerepresents
delta-frontand barrierbeachdeposits(Erpenbeck, 1979;Cumella,l98l) of the final retreat
of the Campanianseawayfrom the region.
Coal depositsof varyingthicknessand lateral
extent and other organic-rich sedimentswere
Iaid down in a variety of delta-plainand backbarrier environments(Erpenbeck,1979).The
upper portions of the Fruitland Formation
and the overlying Kirtland Shale lack welldevelopedcoal depositsthat are presentin the
lower Fruitland. Preliminary analyses of
Fruitland and Kirtland brackish and freshwatermolluscanfaunasindicatea progressive
trend toward fresh-waterenvironments.This
trendimpliesincreasingdistancefrom the PicturedCliffs shoreline(Hartman, l98l).
Both the Fruitland and Kirtland shalewere
named by Max Bauer in 1916for exposures
along the San Juan River in northwestSan
Juan County, New Mexico. Lindsay and
others(1981)suggested
that the Kirtland Shale
be renamedthe Kirtland Formation as Kirtland rocks are predominantly siltstonesand
not shales.The Fruitland Formationis dominantly composedof interbeddedcoals,sandstones,and shales.Threemembersof the Kirtland Shale are recognized:the lower shale
member overlain by the Farmington Sandstone Member in turn overlain by the upper
shalemember (Bauer, l9l7; Reeside,1924).
The contact betweenthe lower shale member
and the Fruitland Formation is imprecise
although many boundaries have been suggested(Fassettand Hinds, 1971,p. l9). Lindsay and others (1981) suggest,rightly in our
view, the presenceof a transition zone betweenthe uppermostFruitland and lower Kirtland Shale. The leaf locality reported here is
8.2 m (27.1ft) abovethe highestcoal contact
of O'Sullivan and others(1972)and Scott and
others(1979)and 5.1 m (16.8ft) belowthetop
of a red-browntabular sandstone,the boundary of Dane (1936) and Hutchison (1981).
Pending more precise delineation of the
boundarythis locality is assignedto the lower
shalememberof the Kirtland Shale.
Locelrrv DEScRrprroN-The locality occursin theSW%NE%sec.32,T. 24 N., R. l3
W. (Fig. l) within a measuredsectionof 19.37
and overm (63.9 ft) of channelsandstones
and
bank depositsconsistingof carbonaceous
noncarbonaceousmudstones and siltstones
(appendixA; Fig. 2). The localityis just below
the shoulder of a hill and has been protected
from weathering by an overlying resistant
siderite concretion. Although the mudstones
are highly weatheredwherenot coveredby the
concretion,the deposit seemsto be a lensshapedpocketthat extendslaterallyabout 3.5
m ( l 1 . 6f t ) .
TABLE 2-CoMpostrroN
oF FLoRA.
Filicophyta (ferns)
Polypodiaceae
Asplenium sp.
Woodwardio 2 crenata
Salviniaceae
Salvinia sp.
Coniferophyta (conifers)
Taxodiaceae
Sequoia cuneata
Anthophyta (fl owering plants)
Monocotyledonae
Cyperaceae
Cyperacties sp.
Dicotyledonae
Salicaceae
Salix lancensis
S. sp. A
S. sp. B
Juglandaceae
Caryaantiquorum
Fagaceae
D ry op hy I lu m subfa I ca t um
Moraceae
Ficus baueri?
F. crossii
F. planicostata
Platanaceae
Platanus raynoldsii
Menispermaceae
Menispermites belli
Magnoliaceae
Magnolia corddolia
Lauraceae
Laurophyllum coloradensis
L. wardiana
L. salicifolium
Leguminosae
Leguminosites
Rhamnaceae
Rhamnus sp.
Zizyphus sp.
Vitaceae
Cissus marginata
Dilleniaceae
Dillenites cleburni
Myrtaceae
Myrtophyllum toneyi
Taxonomic Position Uncertain
Carpites baueri
C. Iancensis
c. sp.
Ficus? trineruis
Rhamnusminutus
unidentifiedinfl uorescence
Fossil leavesare preservedin light-brown
compressions
that vary in quality of preservation from fair to good. Rare, small, poorly
preservedgastropodsand bivalvesare found
in associationwith the leaves and these
specimens
will be studiedby J. Hartman,University of Minnesota. The environment of
deposition was a meandering stream that
periodically flooded interchannel areas,
creatingtransientswampsand ponds.
PREvroussruDrEs-Although the Fruitland
Formation and, to a much lesserextent,the
Kirtland Shale are rich in plant fossils, remarkably little paleobotanicwork has been
done.The only studiesareby Knowlton(1917)
and Lee (1917).Subsequent
publicationsonly
have listed additional taxa (O'Sullivan and
others, 1972;Kues and others, 1977;Tidwell
and others,l98l). Basedon publishedstudies,
o20
or9
or8
ot7
50 cm
( 20 inches)
o?9
028
o27
lg
lg
dq/b
ogg
016
k
Ot5
ss
ol4
lq
or3
q OOO
ot2
99
orl
gg
SHALE,/MUDSTONE y
K
COAL/HUMATE
l9
k
s9
SANDSTONE
BRECCIA
o26
ooo
9 9 LEAVES
9S
lg
o?l
FIGURE
LIES.
ooo
lg
2-Dllcnaruvarrc
oro
lg
oo9
oo8
oo7
oo6
o05
oo4
l9
d9/gg
s9
rg
9S
dg
oo3
k
o02
ool
s
CARBONACEOUS
SHALE
CONCRETION
SILTSTONE
CLINKER
G R A YG R E E N
YELLOW
KHAKI
c
CREAM
CA
C R E A MG R A Y
y9
YELLOWGRAY
gy
GREENYELLOW
b
BLACK
w
WHITE
r
RED
o
ORANGE
br
BROWN
d
DARK
I
LIGHT
v
000
VERY
coNcRETtoN
REpRESENTATToN
oF MAcRosrRATrcRApHrc sEcrroN rN wHrcH LEAF LocAl-rry
Fruitland and Kirtland floras are inseparable.
The newlocalitydescribed
belowrepresents
by
far the largest sample of a local flora yet
described.
Floral composition
The plant taxa identifiedare listedin table
2. Only a few ferns occur in Fruitland-Kirtland floras(Tidwelland others,l98l), and the
florule discussedhere containsonly three genera: Asplenium, Woodwardia, and Salvinia.
Salvinia (plate 1, fig. 1; all further references
to plate figures will be made by the notation
fig. and the number)is interestingbecause
it is
an aquatic, floating fern that requires open
water.
The only conifer in the florule is Sequoia
cuneata,whichbearsshort,Iancelikeleaveson
young branchesand scalelikeleaveson older
branches.Sequoiocuneatais thought to have
been a dominant element of late Cretaceous
peat swampsin the Rocky Mountain region
(Parker,1976).This florule is severelyimpoverishedin conifers,which representonly 3.20/o
of the assemblage
as opposedto 12.3V0for the
entireFruitland-Kirtlandflora (table3).
The anthophyta(angiosperms
or flowering
plants) are the dominant element of the florule, comprising87.l9o of the identicalspecies
(table 2). Monocotsare represented
by a few
specimensassignableto the genusCypercites.
In general,monocotsare lesscommonin this
florule than elsewherein the Fruitland-Kirtland. On the other hand,26 speciesof dicots,
representing15 generaand 13 families, are
presentin the florule. The willow family (Salicaceae)is representedby Salix loncensis(fig.
2) and two undeterminedspecies(figs. 3 and
4). For the oak family (Fagaceae),the only
speciespresentis the extinctD ryophyllum subfalcatum (figs. 5 and 6). This is the first report
of Dryophyllum ftom the Kirtland Shale.The
genusDryophyllum is common in Late Cretaceousfloras of the Rockv Mountains but has
still to be found in the Fruitland Formation
(Tidwell and others, l98l). Three speciesof
figs (Family Moraceae)occur in the florule:
Ficus vaueri, F. crossii, and F. planicostata.
Ficus planicostata (figs.7 and 8) is by far the
most frequentlyencounteredspeciesin the colIection, with specimensranging in size from
1.5x 2.5 cm (.6 x I .0 inches)to 6.2 x 9.3 cm
(2.5 x 3.7 inches).Menispermitesbelli (fig. 9)
is the only member of the moonseedfamily
(Menispermaceae)in the florule. The laurela
(Fauraceae)are represented,
by Laurophyllum
coloradensis,L. wardiana (fig. l0), and L.
salicifolium (fig. l1). Of the family Dilleniaceae,only Dillenites cleburni (fig. l2) is present.The buckthorn family (Rhamnaceaeltras
one specieseach from the genera(Rhamnus\
and Zizyphusin the florule, but the exactspeciesaffinity for the specimens
is yet to be determined. The remaining dicot families in the
florule are eachrepresentedby a singlespecies
and include: Carya antiquorum of the Juglandaceae (walnut family), Platanus raynoldsii of the Platanaceae(sycamorefamily),
Magnolia cordifolia of the Magnoliaceae,
Leguminositessp. of the Leguminosae(pea
family), Cissus marginato of the Vitaceae
(grape family), and Myrtophyllum torreyi of
the Myrtaceae(myrtle family).
In termsof numbersof specimens,
the most
frequentlyencountered
dicot generain the florule are,in decreasing
orderof abundance:
Ficus
Laurophyllum
Dryophyllum
Salix
Myrtophyllum
Rhamnus
Menispermites
Three kinds of seedshave been recovered
from the locality. They are Carpites baueri
(fig. l3), C. loncensis,and C. sp. (fig. 14).
Two speciesof dicotyledonousleavesand an
F
New Mexico Geology
August1982
TABLE 3-PBncnNr or FLoRAspEclESrN sruDy AREAcovEREDrN THrssruDy coMpARED
ro roreL F nurrr-r.N>K rnrlexo (Tidwell and others, I 98 I ).
Species for
total
Fruitland-Kirtland
Filicophyta
Osmundaceae
Schizaeaceae
Cyathaceae
Polypodiaceae
Salvinaceae
9
2
2
I
Coniferophyta
Araucariaceae
Cupressaceae
Taxodiaceae
Incertae sedis
2
I
6.5
9
2
I
5
I
I
J.Z
55
1l
I
I
6
I
I
1
2'.7
I
44
2
I
2
9
4
2
I
I
I
2
I
2
2
2
I
2
1
I
1
6
26
36
I
I
I
Dicotyledonae
Salicaceae
Juglandaceae
Fagaceae
Moraceae
Lauraceae
Platanaceae
Nymphaeceae
Cercidiphyllaceae
Menispermaceae
Magnoliaceae
Saxifragaceae
Leguminosae
Rhamnaceae
Vitaceae
Dillenaceae
Myrtaceae
Cornaceae
Bignoniaceae
Caprifoliaceae
Incertae sedis
TOTAL
Percent
this
report
Percent of total
Fruitland-Kirtland
9.7
J
Anthophyta
Monocotyledonae
Sparganiaceae
Cyperaceae
Palmae
Araceae
Pontederiaceae
Cannaceae
ANT
TERIAL
Species
this
report
).L
5-Z
87.1
).2
3.2
12.3
2.7
2.'.7
1.3
4.1
1.3
12.3
2.',|
1.3
6.8
1.3
'75.3
15.0
1.3
1.3
8.2
1.3
l.J
l -J
83.9
9.7
J -Z
J -Z
J
9.7
9.7
I
J.Z
J
3.2
t.J
J -Z
2.7
1.3
2.'.7
2.'7
2.'.l
1.3
2.7
1.3
3.2
6.5
3.2
I
2
I
I
I
60.2
2.7
1.3
2.7
12.3
5.5
2.'7
1.3
1.3
J.L
J.a
Depositional environment
of aquaticgastropods
Basedon the presence
and bivalves. the fern Salvinia, and the finegrained texture of the sedimentscontaining
the fossils,the depositionprobablytook place
in open, standingwater (Fig. 3). Presumably
smalllakesor pondsexistedon the floodplains
betweenstreamchannels.Lower in the rock
sequence,Fruitland interchannelareas were
occupiedby coal swamps.In contrast,in the
Kirtland, swampswere far less well represented,suggestingbetter drained conditions
during Kirtland time. The standingwater or
pond in which the leavesweredepositedmust
have had a high sedimentationrate to retain
of suchcompleteand well precompressions
served leaves. The higher energy, coarser
(seeB and G of appendixB)
grainedsediments
significantly contain only poorly sorted,
brokenplant fragmentsand no leaves.Ninetyof the long axesof leaves
threemeasurements
and stems were made and indicate current
trend
directions with a northeast-southwest
a).
Gie.
angiosperThe abundanceof medium-sized
mous leaveswith entire or nearlyentire margins and drip points may indicate a warmtemperateto subtropicalclimate during late
Fruitlandand earlyKirtland time.
l.J
19.4
100
6
t)
JI
1.3
8.2
100
L ITHOLOGY
'/,
KEY
A
,'z
'r/,
l m m =l c m
S iIt s l o n es
0
U
00
m
E
I
Fo
u
H
F
'b
I
New Mexico Geology
L e o v e sp r e s e n f
L e o v e so n l o m i n o e
Leoves overlopping
L o r g e o m o u n to f n o n l e o f
moleriol
S m o l l o m o u n lo f n o n l e o f
moteriol
24
23
FIGURE 3-MrcnosrnnucRApHy
t80"
Concretion
Mudstones
B
August1982
(fig. l5) cannotbe assignedwith
inflorescence
certaintyto any known taxon.
Clearly, the remainsof dicots are the predominateelementin the florule. They make
up 83.990 of the florule as comparedwith
60.20/ofor the known Fruitland-Kirtland flora
(table3).
oF PLANTLocALrry
n=93
FIGURE
4-Rosp
IO READINGS
DTAGRAM op onrrNranroN
on 93
STEMAND LEAF FRAGMENTSFROM LOCALITY.
References
Bauer, C. M., 1917, Contributions to the geology and
paleontology of San Juan County, New Mexico; l) Slratigraphy of a part of the Chaco River valley: U.S.
Geological Survey, Prof. Paper 98Q, p. 27 l-218
B a u e r , C . M . , a n d R e e s i d e ,J . B . , J r . , 1 9 2 1 , C o a l i n t h e
middle and eastern parts of San Juan County, New Mexico: U.S. Geological Survey, Bull. 716, p. 155-248
Clemens, W. A., 1973, The role of fossil vertebrates in interpretation of Late Cretaceous stratigraphy of the San
Juan Basin, New Mexico, in Cretaceous and Tertiary
rocks of the southern Colorado Plateau, J. E. Fassett,
ed.: Four Corners Geological Society, Mem.,224 p.
Cumella, S. P., 1981, Sedimentary history and diogenes of
the Pictured Cliffs Sandstone, San Juan Basin, New
Mexico and Colorado: Austin, Texas, Texas Petroleum
ResearchCommittee, Rept. No. UT 8l-1, 219 p.
Dane, C. H., 1936,The La Ventana-ChacraMesa coal
field:U.S. Geological
Survey,Bull.860-C,p. 8l-l6l
Erpenbeck,M. F., 1979,Stratigraphicrelationshipsand
depositionalenvironmentsof the Upper Cretaceouspictured Cliffs Sandstone
and FruitlandFormation,southwesternSanJuanBasin,NewMexico:M.S. thesis,Texas
TechUniversity,T8p.
Fassett,J. E., and Hinds, J. S., 197t, Geologyand fuel resourcesof the Fruitland Formation and Kirtland Shateof
the San Juan Basin,New Mexico:U.S. GeologicalSurvey,Prof. Paper6768,75 p.
Gilmore, C. W., 1917,Contributionsro the geologyand
paleontologyof SanJuan County, New Mexico; 2) Vertebrate faunasof Ojo Alamo, Kirtland, and Fruitland formations:U.S. GeologicalSurvey,Prof. Paper 98e, p.
279-308
Hartman, J H., 1981,Molluscafrom Upper Crelaceous
Fruitland and Kirtland Formations,westernSan Juan
Basin, New Mexico: American Associationof Petroleum
Geologists,
Bull.65, p. 560
Hunt, A , Wolberg,D. L., and Menack,J., 1981,LateCretaceousstratigraphy in the area of Hunter Wash, San
Juan Basin, New Mexico: American Associationof
PetroleumGeologists,
Bull. 65, p. 56t
Hutchinson,P. J., 1981,Stratigraphyand paleontology
of
the Bisti badlandsarea, San Juan County, New Mexico:
M.S. thesis,Universityof New Mexico,219p.
Knowlton, F. H., 1917,Contributionsto rhe geologyand
paleontologyof San Juan County, New Mexico; 4) Flora
of the Fruirlandand Kirtland Formations:U.S. Geoloeical Survey,Prof. Paper98Q.p. 327-353
Kues,B. S , Froehlich,J. W., Schiebout,J. A., and Lucas.
S. G., 197?,Paleontological
survey,resource
assessment,
and mitigation plan for the Bisti-Star Lake area, northwesternNew Mexico: U.S. Bureauof Land Management,
rept to Albuquerqueoffice, 399p.
Lee,W. T., 1917,Geologyof rheRatonMesaand otherregionsin Coloradoand NewMexico:U.S. Geological
Surv e y ,P r o f . P a p e rl 0 l , p . 9 - 2 2 1
Lindsay,E. H., Butler,R. F., and Johnson,N. M., 1981,
Magnetic polarity zonation and biostratigraphyof Late
Cretaceousand Paleocenedeposits,SanJuan Basin,New
Mexico:AmericanJournalofScience,v.281, p. 390-435
O'Sullivan,R. B., Repenning,
C. A., Beaumont,E. C , and
Page,H. G., 1972,Stratigraphyof the Cretaceous
rocks
and the Tertiary Ojo Alamo Sandstone,Navajo and
Hopi Indian Reservations,
Arizona, New Mexico, and
Utah: U S. GeologicalSurvey,Prof. Paper521,65 p.
Parker, L., 19?6,The paleoecology
of the fluvial coalPLATE l-RnpnEspurnrlvE SpECTMENS:
l) Salvinia sp., x 4.62t 2) Salix lancensis,x 0.99; 3) Salrx sp. A, x
forming swamps and associatedfluvial plain environ1.32; 4')Salixsp. B, x 1.32;5, 6) Dryophyllum subfelcatum,S-base,6-apex,both x 0.33; 7, 8) Ficusplaniments in the Blackhawk Formation (Upper Cretaceous)
costata,T-x0.53,8-x1.65;9)Menispermitesbelli,xl.32:'10)Laurophyllumwardiana,x0.40tll)
Lauroof central Utah: Brigham Young University, Geology
phtllum salicifolium, x0.99; 12)Dillenitescleburni, x 1.98; l3) Carpitesbaueri, x 9.24; 14)Csrpites sp.,x
Studies,v. 22, p. 99-ll8
2.64;and l5) unidentifiedinfluorescence,
Reeside,J. 8., Jr., 1924,Upper Cretaceous
x 3.63.
and Tertiary
formationsof the westernpart of the SanJuanBasinof
Colorado and New Mexico: U.S. GeologicalSurvey,
Prof. Paper134,70p.
Total thickness-16.E4
m (55.9ft)
Total thickness-16.84m (55.9ft)
scott, G. R , O'Sullivan,R., Mytton, J. w., 1g79,Recon_ Unit
Thickness
Unil
Thickness
No.
geologicmap of the Alamo MesaWestouad(cm, inches)
naissance
Description
(cm, inches)
No.
Description
rangle,SanJuan County, New Mexico:U.S. Geoloeical
amber blebs l-2 mm in diameter:
Survey,Misc. Field SrudyMap MF-1074,I sheet,Jcale 026 White sandstone, medium-grained;
about l0q0 organic clasts overall but
dull coal
l:24.000
l8
plant-rich
with
grades
laminae;
upShomaker,J. W., 1971,Bisti Fruitlandareain strippable
018 Dark-gray-green shale; rich in plant
ward
into
027
96
low-sulfur coal resourcesof the San Juan Basin in New
debris (20-3090)
20
Mexico and Colorado: New Mexico Bureauof Mines and
02s G r a y - g r e e n m u d s t o n e : 5 - 1 0 9 0
017 Dark-gray mudstone; lacks plant
MineralResources,
Mem. 25, p. I l0-l l6
organlc matter; very rare occurdebris or carbonaceous material,
Tidwell,W.D., Ash, S R., and Parker,L. R., 1981,Crerarences of leaf fragments
grades upwards into 018
148
59
66
26
ceousand Tertiary floras of the San Juan Basin. in Ad016 Olive sandstone, fine-grained
024 G r a y - g r e e n m u d s t o n e ; w i t h
40
I6
vancesin San Juan Basinpaleontology,S. G. Lucas,J.
015 Gray-green mudstone; occasional
abundantly preserved leaves just beK. Rigby, Jr., and B. S. Kues,eds.:Universityof New
occurrences of plant debris in carbolow a sideritic concretionary layer
MexicoPress,394p.
naceouspockets
forming a protective cap; leaf-bear64
26
014 White sandstone, medium-grained;
ing horizon laterally discontinuous
148
well
prominent
indurated
and
ledge
023 Sandy mudstone, gray-green; little
former
36
14
organic material present
48
t9
APPENDIX A-Mresunso
SECTToN;
MEAsuREDBy
013 Gray mudstone; with about l59o
022
White
s
a
n
d
s
t
o
n
e
.
fineto
A. HuNr AND J. MENAcK, JuLy 1980, usrNc e
organic debris
18
7
medium-grained; crossbedded lamiBnuNtott coupAss ANDJAcoB's srAFF
012 Gray-green
mudstone,
very
nae; less than lOqo plant debris
Total thickness-16.84m (55.9ft)
Unil
No.
Description
Thickness
(cm, inches\
029 White sandstone, medium-grained;
about l5qo organic clasts
4l
I6
t8
5lOqo plant debris in thin laminations; grades upwa:d into 022
l8
590 organic matter; dark-brown sideritic concretions present
0 1 9 Dark-gray
92
20
020 Light-gray mudstone with less than
027 Olive sandstone, fine-grained; with
about 5q0 organic matter; olive laminae alternate with light-gray finegrained laminae
carbonaceous (50-6090); very deep,
deep weathering developed (45 cm);
characterized by development of
vegetation along the outcrop of this
unit
021 White sandstone, fine-grained;
028 Lighrgray
mudstone; finely divided
sand-sized plant fragments
but
locally more carbonaceous; locally
red-brown color developed: iron
staining in some laminae; fines upward inro 023
J /
lignitic
(weathered) to black,
horizon; very friable with
82
33
147
59
011 White
sandstone,
fineto
medium-grained; about 20qo plant
fragments in matrix; approximately
l09o clay in thin laminae less than I
mm thick and clay pebbles up to 2
cm x I cm; poorly developed ripple
marks
78
31
(continued on p. 48)
New Mexico Geology
August1982
45
Palarlto fault zone
leaflocality
LateCretaceous
(continuedfrom
(continuedfrom p. 45)
p.4I)
References
APPENDIX
A (continuefi
Bailey,R. A., Smith, R. L., and Ross,C. S., 1969,StratiTotrl thickness-16.t4 n (55.9ft)
graphic nomenclatureof volcanic rocks in the Jemez
Thickness
Unit
Mountains, New Mexico: U,S. GeologicalSurvey, Bull.
(cm, iaches)
No.
Description
r274-P,p. l-19
Cordell, L., 1979,Gravimetric expressionof grabenfault0 1 0 White sandstone,medium-grained;
ing in Santa Fe country and the Espafiola Basin, New
with large plant fragments up to 5
Mexico: New Mexico Geological Society, Guidebook
cm'!;well induratedand forms char3fth field conference,p. 59-64
acteristic popcorn surface texture
Dalrymple,G. 8., Cox, A., Doell,R. R., and Gromme.C.
upon weathering;somehoodoo (colS., 1967, Pliocene geomagneticpolarity epochs:Earth
umnsor pinnacles)development
89
36
and PlanetaryScienceLetters,v. 2, p. 163-173
009
White
sandstone,
fine-grained;
Doell, R. R., Dalrymple,c. B., Smith, R. L., and Bailey,
about 590 plant debris concentrated
potassium-argon
R. A., 1968, Paleomagnetism,
ages,
in laminae. Undulating bedding
and geology of rhyolites and associatedrocks of the
finely dcveloped; well indurated
Valles caldera, New Mexico: Geological Society of
with fine laminationsand mud DartAmerica,Mem. l16, p.2ll-248
24
lngs
60
Galusha,T., and Blick, J. C., 1971,Stratigraphyof the
008 Dark gray-greenmudstonewith 15SantaFe Group, New Mexico: AmericanMuseumof Na2090 plant debris up to 3.5 cm';
tural History,Bull., v. 144,art. l, 128p.
30
I2
coarsensupward
Golombek, M. P., 1981,Ceometry and rate of extension
across the Pajarito fault zone, Espanola Basin, Rio
00? Gray-green mudstone with about
Grande rift, northern New Mexico: Geology, v. 9, p.
590 plant fragments and stems;
2l-24
gradesupward into 008
28
-,1982,
pajaGeology,structure,and rectonicsof the
006 Sandstone,white, medium-grained;
rito fault zone in the EspaflolaBasin of the Rio Grande
with large fragmentsof plants up to
rift, New Mexico: GeologicalSocietyof America, Bull.,
5 cm'?;about l0qo plant content
25
ln revlew
gray-green; with
005
M
u
d
s
t
o
n
e
,
Griggs, R. L., 196/.,Geology and ground water resources
approximately l09o carbonaceous
of the Los Alamos area, New Mexico: U.S. Geological
debris;coarsensupwardsinto 006
6l
Survey,Water-supply
Paper1753,107p.
Jiracek, G. R., 1974, Geophysicalstudies in the Jemez 004 Carbonaceousmudstone,dark-gray;
up to 40qoplant debrisis up to 2 cm'
Mountains region, New Mexico: New Mexico Geological
poorly sorted;coarsensupwards;beSociety,Guidebook25th field conference,p. 137-144
comesmuch lesscarbonaceous
laterKelley, V. C., 1979, T€ctonics, middle Rio Grande rift,
28
l1
ally (aboutl09o)
New Mexico, in Rio Granderift-tectonics and magmatism, R. E. Riecker,ed.: Washington,D.C., American 003 Olive sandstone, medium-grained;
GeophysicalUnion, p. 57-70
with some iron staining along bedManley, K., l9?9, Stratigraphyand structureof the Espadingplanes;5-1090plantdebris
ll7
flola Basin, Rio Granderift, New Mexico, in Rio Grande 002 Gray siltstone;590plant debris;iron
rift-tectonics and magmatism, R. E. Riecker, ed.:
stainingin fractures
l8
Washington, D.C., American Geophysical Union, p.
001
White
lenses
sandstone;
fine-grained
7l-86
of sand rich in carbonizedplant deReilinger,R. E., and York, J. E., 1979,Relativecrustal
bris and silt lacking plant debris;
subsidencefrom levelingdata in a seismicallyactivepart
lensessubparallelto bedding; fines
of the Rio Grande rift, New Mexico: Geology, v. 7, p.
upward into 002; much lateral varia139-143
t2
tion in plant debriscontent(5-20q0)
30
Smith, R. L., Bailey,R. A., and Ross,C. S., 1970,Geologic map of the JemezMountains, New Mexico: U.S.
APPENDIX B-Msnsun so sEcrrott.
GeologicalSurvey,Misc. Inv. Map I-571
Stearns,C. E., 1943, The Galisteo Formation of northUnit
Thickness
centralNew Mexico:Journalof Geology,v. 51, p. 301No.
Description
{tr'm.inchesl
319
o
Concretion, dark-brown; siderite
with veins of barite; rare, poorly
preserved leaf impressions extend
laterally1.8m (5.9ft)
35.6
Unit
No.
Description
Thlckness
(cm,lnches)
Siltstone, gray-green; scattered
subrounded plant fragments; wellsorted,averaging5 mm (.2 inches)in
15.2
diameter
c Mudstone, gray-green; a few
scattered stem fragments; poorly
sortedup to 3 x 5 cm (1.2 x 2 inches)
3.8
D Mudstone, gray-green; occasional
horizons with leaves 3 cm (1.2
inches)in length and also horizons
of poorly sortedstemsup to 1.3 x 2
22.8
cm (.5 x.8 inchesl
Mudstone, gray-green; many
jumbled leaves,many of which overlap; leavessubcomplete2-5 cm (.8-2
inches)in length,small fragmentsup
to 5 mm (.2 inches)in length; poorly
sorted stem fragments l-5 cm (.+2
inches)in lengthand up to .75 cm (.3
inches) wide; slickensidesup to 39
cm (16 inches) in length, leaveson
laminaeaveraging.3 cm (.12 inches)
17.8
apan
Mudstone, gray-green; scattered
Ieavesfew in number: (a), lens of a) 7.5
few scatteredcompleteleavesgrades
laterally into stems and poorly
sortedsmall plant fragments,but no
leav€s;stems 5-10 cm (2-4 inches)
long and up to I cm (.4 inches)wide,
fragmentsare subrounded2-.25 mm
(.08-.01 inches) in diameter; (b) b) 5.0
sameas lateral, stem-richportion of
(a), sharp contact with plant-rich
portion of (a)
Lateral from (a) and (b) siltstone,
yellow-green;few broken plant fragments (no leaves);lens-shapedcross
section7 x 60 x 15 cm (2.8 x24 x 6
inches)
7,0
Mudstone, gray-green; full of
overlapping complete leaves that
cover l0o9o of surface on laminae
about every .5 cm (.2 inches);intervening layers produce complete
7.7
leavesnot overlapping
Mudstone, gray-green;large stems
5-10 cm (2-4 inches)long and I cm
(.4 inches) wide, also many small
stempieces,subroundedfrom 3 to 8
mm (.12to.32 inches)in diameter
15.2
J Grades down with less stem to
subrounded fragments less than 2
mm (.08 inches)in diameter to un45.9
fossiliferousgray-greenmudstone
6,1
t.5
9.t
7.1
3.0
2.0
2.8
3.1
3.1
18.4
tr
ion ftolr or8rntr.ron
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