Chronostratigraphy and Tectonic Significance of Lower Cretaceous ...

PART III REGIONAL REGIONAL STUDIES OF FORELAND BASINS

Copyright © 2012, Society for Sedimentary Geology (SEPM)

CHRONOSTRATIGRAPHY AND TECTONIC SIGNIFICANCE OF LOWER CRETACEOUS CONGLOMERATES IN THE FORELAND OF CENTRAL WYOMING

MICHAEL T

MAY

LLOYD C FURER

Department of Geological

Sciences

GARY D

Department of Earth

Sciences

ERIK P

KVALE

LEE J

AND

Indiana

University Bloomington JOHNSON

Dartmouth

Hanover

College

SUTfNER

IN 47405

NH 03755

AND

JAMES H

Department of Geology

MEYERS

Winona State

Winona MN 55987

University

Intra and inter basinal correlations between outcrop and subsurface over most of northern and central Wyoming indicate foreland of central Wyoming occupy three distinct bearing conglomerates in the lower Cretaceous Cloverly Formation in the Basin and reflect stratigraphic levels The two older conglomerates are in the lower Cloverly Formation in the western Wind River of the basin northerly to northeasterly dispersal The youngest conglomerate is in the upper Cloverly Formation in the eastern portion gravels in this interval also were transported to the north and northeast The two older conglomerates are separated from the youngest conglomerate by up to 35 m of purple to gray smectite rich mudstones that contain distinctive 10 to 90 em thick layers of white to dark green devitrified tuff as well as silica and carbonate nodular beds 128 Ma have been obtained from three samples of tuff in the Wind River Basin These tuffs can be correlated Fission track ages of 125 Fission track ages of to prominent tuffs further north in the Bighorn Basin where a paleomagnetic stratigraphy has been established River zircons from devitrified tuff layers and magnetostratigraphy of mudstones suggest that the older two conglomerates in the Wind Basin were deposited between 133 and 128 Ma and the youngest conglomerate at about 118 to 115 Ma Three dimensional spatially controlled and temporally constrained reconstructions of paleodrainage systems for Cloverly conglom erates illustrate the complexity of fluvial drainage networks within the evolving Early Cretaceous foreland basin Sand body geometry and dispersal patterns within these fluvial networks were partially controlled by tectonic activity which created a series of northeast oriented horsts and grabens in the Wind River Basin Location of trunk rivers was controlled by the positions of grabens within the

ABSTRACT that chert

basin

models which have

INTRODUCTION

The

goal

ofthis

paper

is

to

document the

spatial

and

tem

poral distribution of fluvial sandstones and conglomerates in the lower Cretaceous Cloverly Formation in central Wy oming in order to better understand the tectonic and de positional history of the early stage of development of the Rocky Mountain foreland basin Delimiting areas of abrupt thickness changes of conglomerates and sandstones in the earliest Cretaceous foreland basin fill has made it possible to identify areas of increased accommodation space for flu vial sediment deposition and preservation Fluvial depositional systems are easily influenced by sub Burnett and Schumm 1983 weaknesses in linear structural along the upper lithosphere often controls the location of major the temporal rivers in sedimentary basins and therefore

tle tectonism

Russ

1982

Recurrent movement

distribution of nonmarine facies within a basin fluvial systems can be used to define intraforeland basin structural features that actively influenced distribution of sedimentary facies In the Rocky Mountain foreland ba and

spatial

Thus

paleodispersal indicators and conglomerate thickness trends indicate possible fault locations and assist in rec ognizing intrabasinal tectonic motion which influenced dif ferential subsidence and paleodisperal DeCelles 1984 1986 1988 Meyers and others 1992 Schwartz and DeCelles sin

1993

Kvale and Vondra

Outcrop and subsurface mapping of fluvial lithostrati graphic units constrained by chronostratigraphic horizons ash beds in the fine grained facies can define spatial and temporal migration of subsidence in nonmarine foreland ba sins Most previous depositional models for foreland basins have

not been

stratigraphic

all available subsurface and chrono Consequently previous foreland basin

based data

on

Stratigraphic Evolution of Foreland Basins SEPM Special Publication No 52 Copyright rJ 1995 SEPM Society for Sedimentary Geology ISBN 1 56576

016 6

synthesized paleocurrent

and thickness

data obtained mostly from outcrop have failed to fully iden tify stratigraphic complexities that reflect structural and geomorphic complexities within the basin This paper in

bet tegrates data from both the outcrop and subsurface for ter three dimensional and early complexity understanding the subsidence and depositional history of the Rocky Mountain

foreland basin The

Mountain foreland basin formed

Rocky

east

of the

Sevier fold thrust belt as part of the Cordilleran mobile belt that extends from Alaska to Mexico The timing of the on set

of deformation in the Sevier belt in Idaho

Wyoming

and Utah in part has been interpreted on the basis of lateral and vertical lithofacies relations of Lower Cretaceous strata in

Wyoming

and Montana

Heller and Paola

1986

terpreted

as

early

nonmarine upper

Curry

1989

1960

Heller and others

These strata have

Cloverly and Lakota Formations and their alents in the Gannett der

been in

foreland basin fill and include the mostly Jurassic Morrison and lower Cretaceous

Group along

the

western

Wyoming

equiv

Idaho bor

I

Fig

timing of thrust movement history of the basin several Lower Cretaceous chert bearing conglomerates conducted throughout the Western Interior of the

In order to better understand and

subsequent

studies of have been U S A

and Canada

1970 Corman ever

1972

Heller and Paola 1989 Schultheis Knight 1978 Varley 1982 How

conglomeratic intervals previously have been by use of lithostratigraphy alone and because

because

correlated most

subsidence

studies have been conducted in

taceous

varied

relatively

local

areas

of Lower Cre

interpretations stratigraphy and its tectonic significance are quite For example deposition of Lower Cretaceous chert

independent

of each

other

98 98

MICHAEL T. T MAY MAY ET ET AL. AL MICHAEL

EASTERN

IDAHO

WIND

IDAHOWYOMING WYOMING BORDER BORDER Bur fWer Fm

NORTHERN

WIND RIVER RIVER BASIN BASIN

NORTHERN BIGHORN BIGHORN BASIN BASIN

... -

Belr,",-

....

-

EASTERN POWDER POWDER RIVER RIVER BASIN BASIN

.--

ThermopolisSh ' -

rm.

FaN Rivel

"'OM,

'.........-

Sykes Mountlin

Smoot

R

"RUlty8ldl'

...... 0

~

I• I

u

Ma

113

113

Formltion

!J

it ~

Ma

ALBIAN ALBIAN

115

115· APTIAN

APTIAN

a

~I

~II

~ 11

~ 2i

......

o

fo_

jj

II

f

-

J& -.... PeteBon

u

L>.

i3

Ij

II

f I~I

II

i

2i

f1

Uioto

119

\19

~

FIELD METHODS METHODS FIELD 125

'25'

!

8 8 f

i

jj

ff

11

2i

j

Il

j

;

~ 2i

29

129'

.;;

NEOCOMIAN NEOCOMIAN 3

'3"

Ephrarm

EpflrWn

--~

_. - -

-

7

~ w

MorrisOn

'e-' Ephraim

E_ .........

-Sl

one

........

........

ion

Kvale l986

ThisSlucIy ThisS1ucty

eoo- ...

..........,

ion

fo_

Conner and

.......""""" Morrison

........

......

1969 Eyer Eytr.ll169

KonAt.lIi'ilMi modified 1 -)

Hatch 1980

HIldl,l!MlO furef.1910

Film 1970

'44

TITHONIAN TITHONIAN

Momson

52 152 KIMMERIDGIAN IOMMERIDGJAH 55 155

OXFOROIAN OXFORDIAN

l959 Wagoe WIQge,l9S9 Bolyard and _dona 1966 McGreQOf Mdi~.'966

FIG and Lower Stratigraphic nomenclature FIG. II.-Stratigraphic nomenclature of of Upper Upper Jurassic Jurassic and Lower strata of north central Rocky Mountain region A and B con Cretaceous strata of north-central Mountain region. A and B conthe western Wind glomeratic glomeratic intervals intervals within within the the Cloverly Formation Formation in in the western Wind River clastic units mud River Basin Basin are defined defined as coarse clastic units with with intercalated intercalated mudstones overlain by interval deposition. deposition stones overlain a thick thick mudstone mudstone representing representing C C -interval In In the the eastern eastern part part of of the the Basin Basin, the the C C interval interval can be be subdivided subdivided into into a mudstone non mudstone overlain overlain by by a conglomerate conglomerate. Asterisks Asterish with with ages ages represent nonstandard 1990 all standard boundaries boundaries based based on on Swierc Swierc (1990); all other other age age boundaries boundaries based based on on Palmer Palmer 1983 (1983). Cretaceous

are

as

can

a

a

either (I) I synchro gravels in in Wyoming Wyoming isis considered considered to to be be either synchrogravels nous e g of thrusting (e.g., Armstrong nous with with an an initial initial episode of oth and Oriel, 1965 1965; Wiltschko Wiltschko and and Dorr Dorr, 1983 1983; Heller Heller and and oth2 post ers, 1986 1986), or or (2) post-orogenic and indicative indicative of of aa period period orogenic and of Kvale and of tectonic tectonic quiescence (Kvale and Beck Beck, 1985 1985; Heller Heller and and others 3 pre been others, 1988 1988), or or (3) pre-orogenic, having been generated orogenic by regional regional uplift uplift or or thermal thermal doming doming that that occurred occurred just just prior prior by to Heller and to Sevier Sevier thrusting thrusting (Heller and Paola Paola, 1989 1989). Data in this this study study permit permit an an estimate estimate of of the the Data presented presented in absolute absolute age age ranges ranges of of three three distinct distinct stratigraphic stratigraphic intervals intervals in in the the Cloverly Cloverly Formation Formation, designated designated informally from from old oldest des est to to youngest youngest as as AA, BB, and and C C (Fig. These letter letter-desFig II). These ignated intervals intervals contain contain chert chert-bearing conglomerates and and ignated bearing conglomerates in the the Wind Wind River River and and Bighorn conglomeratic sandstones sandstones in conglomeratic Basins Basins. Our Our findings findings contradict contradict earlier earlier studies studies that that suggest suggest the the existence existence of of only only one one significant significant conglomerate conglomerate in in the the Formation e 1960 (e.g., Moberly, 1960; Mirsky, 1962; Cloverly Formation Cloverly Moberly g Mirsky 1962 Hooper, 1962 1962). Moreover Moreover, we we have have identified identified at at least least two two Hooper ers

the Morrison and Cloverly ofthe Morrison and Formations were were Outcrops of Cloverly Formations studied along the margins of the the Wind Wind River River and and southern southern studied along the margins of Basins of of central central and and west-central west central Wyoming Bighorn Basins Wyoming (Fig. Fig 2 distribution of of Cloverly was mapped 2). Areal distribution Cloverly conglomerate conglomerate was mapped the two two areas. 100 km km of of outcrop in the areas along approximately 100 outcrop in Over 1000 1000 paleocurrent measurements measurements were were made Over made mainly mainly from trough to cross beds beds and and were were categorized from trough cross categorized according according to lithofacies and and stratigraphic position. intra bas Inter and lithofacies Interand intra-basposition inal correlation correlation was was based on a database that includes 75 inal based on a database that includes 75 measured stratigraphic sections sections and and correlation correlation of of300 wire 300 wiremeasured and sample logs. Detailed line and results of ofthe the areal areal mapping line logs Detailed results mapping of conglomerates and of of the the paleocurrent and petrographic of conglomerates and paleocurrent and petrographic studies for for the western part are the western of the the Wind Wind River River Basin are studies part of found in in Meyers and and May b and others others (1992) 1992 and found I992a b). May (1992a, Absolute age ranges for cor Absolute-age for regional chronostratigraphic corchronostratigraphic ranges relations were were established established by zircon zircon fission-track fission track age-dating relations age dating euhedraI zircons zircons obtained from from devitrified devitrified tuffs. tuffs of irradiated euhedral MORRISON CLOVERL Y STRATIGRAPHY STRATIGRAPHY MORRISON-CLOVERLY

Introduction Introduction

coarse

a

and Oriel

and distinctive extensive devitrified devitrified tuff tuffbeds beds and distinctive pepe regionally regionally extensive and lacustrine beds between between the the Band Band C C horizons and lacustrine beds dogenic horizons dogenic in tuff and subsurface sections The conglomerates in outcrop conglomerates outcrop and subsurface sections. The tuff beds pedogenic horizons and cor and lacustrine lacustrine beds beds can can be be corpedogenic horizons beds, related from from the the Bighorn Basin Basin into into the the Wind Wind River River Basin Bighorn Basin related and farther east into the Hanna Basin DeCelles and Bur and farther east into the Hanna Basin (DeCelles and Burden 1992 in the conglomerate-bearing intervals in Dating the den, 1992). Dating conglomerate bearing intervals the Cloverly Formation permits tectono inter the tectono-stratigraphic interCloverly Formation permits stratigraphic of the the history ofdrainage Sevier evolution in in the the Sevier pretation of history of drainage evolution pretation foreland basin. basin This This interpretation structural that structural interpretation suggests foreland suggests that within the the early foreland basin basin was was significant partitioning within early foreland partitioning significant in controlling ofthe the drainage controlling development of drainage system. in system

The upper Jurassic Morrison and lower Cretaceous CloThe upper Jurassic Morrison and lower Cretaceous Clo

a regionally extensive interval are part of a interval verly Formations are part of of fluvial fluvial and and lacustrine sediments sediments deposited break of during a deposited during a break

in marine sedimentation within within the Western Interior SeaSea in marine The Morrison Formation conformconform way of of North North America America. The way the glauconitic sandstones sandstones of of the the marine marine upper ably overlies the upper Jurassic Sundance Formation and consists of a succession of a succession Jurassic fluvial cemented quartzo-feldspathic of alternating alternating calcite calcite-cemented, quartzo feldspathic fluvial and eolian sandstones and and caliche caliche or carbonate lacustrine carbonateand eolian sandstones or lacustrine and red bearing, green red mudstones mudstones. green and bearing An Morrison and and An unconformity isis present present between the Morrison the Formations Its presence is identi identithe overlying overlying Cloverly Formations. presence is constraints established for fied by magnetostratigraphic constraints mudstones Morrison Cloverly section (Swierc, Swierc 1990) 1990 mudstones in the the Morrison-Cloverly and supported by by regional regional subsurface subsurface-outcrop and isis supported outcrop correlation chert (May, 1992b). The The Cloverly Cloverly Formation Formation contains contains chertMay I992b to coarse-grained sand coarse grained sandbearing conglomerate conglomerate and and medium medium to bearing stone of stone, intraformational conglomerate conglomerate made made up mostly up mostly of reworked and reworked lacustrine lacustrine and pedogenic pedogenic carbonate carbonate clasts clasts, and variegated smectitic smectitic mudstone mudstone. In central Wyoming, variegated Wyoming the is overlain overlain by by the "rusty beds" sand sandCloverly Formation Formation is rusty beds stone to stone of the the Thermopolis Thermopolis Formation which is is equivalent equivalent to Formation which the Sykes Sykes Mountain Mountain Formation Formation of the Bighorn Bighorn Basin. of the Basin The of Albian Albian marine marine transgres"rusty beds" mark mark the the initiation initiation of rusty beds transgres sion into this Young, 1970). this area area (e.g., e g 1970 Young

99

CRETACEOUS CRETACEOUS CONGLOMERATES CONGLOMERATES IN IN THE THE WYOMING WYOMING FORELAND FORELAND

,

(

WYOMING WYOMING

• Study Study

99

~

Q1,;

L.~'o ....

Area Area

0

1

Cody Cody

~to "1r

~.

i9c;1

~S

V V

.,

9-

\S}-t.1 Ten Sleep 0

S l6 "16,s

qrO~q ilrO il

44 N 44'1\

~,o

li'q'l illl919 :ge

~,,taSi~_

Kt Kl

Shale Thermopolis Thermopolis SNIo

K~

Fall River River 5ands1one Sandstone Fall

Krl KrlI Kcv um Kcv(um)

Beds Rusty Rusty Beds Mudstone Cloverly Cloverly Upper UpperMudston. Interval (CC Int,MI) Cloverly C10YertyUpper UpperCong\omertt, Conglomerate interval (CC InteMl) LowerConillom.ratl Cloverly Cloverly LOWOf Conglomerate and B B Int.MIs) InteMls (AA and

KIT

t

~

Kcv(uc) Kcv uc Kcv Ie Jm Jm JS Js

A.

--

Jm

A

Js

y Y

u.

We8t West

200 200 21 32N 97W 21-32N-97W

14-33N-94W 14 33N 94W

Twin Twin Creek Creek

.\.

-Kmcl

l

~

Kl

--

Kt

KrlI

'-

1'.: ....

Kcv um Ktv(um)

::-:".

J ..01,..... ,"!,:

Kcv(lc) Kcv1e

•

:r

;:J

-

0;i

y' Y

East

JI

North North

50 so

Muskrat Muskrat Field Field 3-33N3 33N 92W

Muskrat 20-34N-88W Muskrat Creek Creek 2O 34N 88W 4 33N 90W Rattlesnake Hills 4-33NRattlesnake Hills 29 34N 88W 29-34N-88W

Js Js

.

Wildhorse Butte Butte Wildhorse 16-35N-88W 16 3SN 88W

Arminto Arminto Unn Unit 13 37N 86W 13-37N-B6W

l

~

~

Buffalo Creek Creek Road Road Buffalo 19 38N 86W 19-38N-86W

J

-1·'

I

.)

Jm Jm

B.

Mudstone/lull Mudstone Tuft Ss Int'MI al Co"lllomeratic ConglomeJ3tic 50. Intt

Kt Kt

L-

B

I

Blue Blue Ridge Ridge 25-33N-92W 2S 33N 92W

Kd-(si~)_m Kd sitt datum

.'to ~-

Green 10 to W?ti1e WMe Siliceous SiUceous Green

0

o

~

MorrisonFormation Formation Monison Sundance Formation Sunda"'"formation

Unconfonnily Unconfonnity

ii 01

12-31N-9BW 12 31N 98W

one Muddy Muddy 5andstone

':'--

[

. • :. ?

r

.;' . 1

s

\

t

~..

-_

~

Kcv(uc)

)

-

Jm

Js

P'

~ I

1

of Aand FIG 4 A X X Northwest to to southeast southeast cross cross section section on the west west side side of of the the Wind Wind River River Basin. Basin Kcv Kcv (Ie) Ie denotes denotes the the combination A and FIG. 4.-(A) X-X'-Northwest on the combination of of the the Wind Wind Bconglomeratic intervals intervals of the Cloverly B conglomeratic of the Formation of of Figure I (B) B Y-Y'-West Y Y West to to east east cross section across the southern southern margin cross section across the Cloverly Formation Figure I. margin of Location River Basin. Kcv Kcv (uc) River Basin uc denotes denotes the the uppermost C conglomerate of Figure 1 whereas whereas Kcv Kcv (lc) Ie is is as as in in Figure 4A Location uppermost Cloverly Cloverly conglomerate conglomerate or C conglomerate of Figure I, Figure 4A. in Figure 2 of both both cross cross-section of section lines lines is is given given in Figure 2. or

mented throughout mented throughout much much of of southwestern southwestern Montana Montana by by DeCelles Thompson (1984). DeCelles (1984) and Thompson 1984 and 1984 In the western and and west-central Wind River In the western west central Wind River Basin, Basin concon glomerates are present only near the base of the Cloverly are near the base of the glomerates present only Cloverly Formation lower conglomeratic A and and B-interB inter Formation (Cloverly Cloverly lower conglomeratic Avals in Fig Fig. 4A), at least 50 below the the "rusty 4A at least vaIs in 50 m m below beds of of rusty beds" the the overlying Shale The The lower lower conglomerate overlying Thermopolis Thermopolis Shale. conglomerate bearing and B-interval the western A and B interval in in the western part of the the basin basin bearing Apart of is overlain by C-interval is overlain Kcv (urn) or upper the C interval (designated upper by the designated Kcv is comprised mudstone in Figs. 4, 5 5). The mudstone in The C-interval C intervaI is of up comprised of Figs 4 up to m of red, orange, light brown, and purple smectitic to 35 of red brown and smectitic 35 m purple orange light mudstones beds of lavender or lilac beds of Love, Love 1948; 1948 mamudstones ("lavender" or "lilac" Little Sheep Mudstone Member Member roon and and purple purple beds beds of of the the Little Sheep Mudstone of Swierc, 1990), and smectitic mudstones. Most of Swierc 1990 and gray smectitic mudstones Most gray mudstones in the the C-interval, particularly the or ormudstones in C intervaI particularly the purple or or purple ange/red ones, are intercalated with nodular silica ,and barite ange red ones are intercalated with nodular silica and barite beds and and nodular nodular and beds and bedded bedded nonmarine nonmarine micritic micritic limestone. limestone um

or

ma

roon

These rock rock types B inter These are rarely in the the AA and and B-intertypes are rarely present present in from vals. vaIs Discontinuous Discontinuous sandstones sandstones ranging in thickness thickness from ranging in 0.1-0.5 0 1 0 5m m occur occur near near the the base base of ofthe the C-interval. C interval In contrast, eastern part of In contrast in in the the eastern the basin, basin conglomerpart of the conglomer For ates ates are to the the upper the Cloverly are confined confined to of the Cloverly Forupper part part of mation, nearly lateral to or approximately] -5 m below the 1 below the mation nearly lateral to or approximately 5 m base beds" (Cloverly upper conglomeratic C base of of the the "rusty beds rusty Cloverly upper conglomeratic Cinterval 4B). Our on-going investigations suggest 4B interval in Fig. Our on Fig going investigations suggest that that a similar similar stratigraphic of upper Cloverly stratigraphic relationship relationship of upper Cloverly the Bigconglomerate above smectitic mudstone exists in smectitic mudstone exists in the Big conglomerate above horn 5, and that this conhorn Basin, Basin as illustrated in in Figure 5 and that this con as illustrated Figure intervaI mudstones glomerate C-interval farcorrelates to to the the upper C mudstones far glomerate correlates upper west ther ther west. In In much much of of the the Wind the western western part ofthe Wind River River Basin, Basin aa part of A chert-pebble is the basal Cloverly unit (Achert pebble conglomerate is the basal unit conglomerate Cloverly interval) the Morrison Forma interval and and lies lies unconformably Morrison Formaunconformably on the tion. contact has to ]5 IS m tion This This contact has local local relief relief ranging from 66 to ranging from a

on

m

104 104

MICHAEL T. T MAY MAY ET ETAL. AL MICHAEL X X" Northeast Northeast X X

NowaterAlea Area Nowatar 31 T43N-R89W T43N R89W 31-

Southwest Southwest

TenSleep Sleep Anticline Anticline Ten l T46N R89W l1-T46N-R89W

A A

X"

X

X X'"

South South Ten Sleep Anticline Ten Anhcline l1 T46N R89W l1-T46N-R89W

North North

Hidden Dome 29 T48N

R90W

EXPLANATION EXPlANATION

F~I~

FhI

100 100

KInd sandstone Kmd Muddy Muddy sandstone Dakota slit silt marx.er Kd Kd Dakota marker

KtKt Thermopolis Thermopolis Shale Shale Krb Rusty Rusty beds beds Kcv(um) Kcv um Cloverfy Cloverly upper mudstone upper mudstone C e Interval interval KCY(uc) upper COllOlomerate Kcv uc Cloverly upper Cloverly conglomerate

30

30

C interval Cinterval

Big

Kcv(lc) Kcv lc Cloverly Cloverly lower conglomerate conglomerate A A and and B B intervals intervals Morrison Jm Morrison Formation Jm Js Js Sundance Sundance Formation Formation to white c:;lo CIJI lID Green to white siliceous siliceous mudstone/luN mudstone tuff

Horn River

12 T54N

R94W

Krb

G G

-MO MO

-M3 M3

M8

-M19 Mt9

B B

IT:-» ~:·Il r

Tufts Tuffs Glauconite Glauconite

Conglomeratic sandstone Conglomeratic sandstone

105 105

CRETACEOUS THE WYOMING CRETACEOUS CONGLOMERATES CONGLOMERATES IN IN THE WYOMING FORELAND FORELAND

formational pebble conglomerate (Figs. SA). The The intra intra-formational-pebble Figs 44, 5A in B interval overlies (B-interval) overlies and isis locally locally incised incised into into the the A A-inII 1992a terval terval chert chert-pebble conglomerate (May, I992a, Fig. 11). May Fig pebble conglomerate interval conglomerate is is More More frequently frequently, however however, the the BB-interval interval conglomerate by 10 m of of separated from from the the A A-interval by 1I-10m separated Basin secsec mudstone mudstone as as illustrated illustrated by the the NW NW Wind Wind River River Basin X in tion of section section X X-X" in Figure 5A SA. tion at at the the southwest end end of

TS4N R94W

n4H-R94W

113

-

113

Ii U

Mtfl

.... ,...

115 e

Sec 13 SNW sec.13-S£NW

'"

s.,u. Mbl.

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Ii

121

I

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50

C

c

il

PIIrpIlIMudstone

'"

WITHIN WITHIN THE THE CLOVERLY CLOVERLY FORMATION FORMATJON Ul

General General Constraints Constraints

0 w

Uz

have been collected from outcrops at three sites within the Wind River Basin-Maverick Springs Dome (MS), Ar2 Fission track minto, and in in the the Rattlesnake Rattlesnake Hills Hills (Fig. Fission-track minto Fig 2). Ma Our cor 125 I 28 dates Our cordates on on these these samples samples range range from from 125-128 Ma. these relations indicate indicate that that the mudstone interval interval containing these relations to the the upper Little equivalent to upper Little tuff beds beds isis approximately equivalent tuff Sheep Mudstone Mudstone Member of of the the Cloverly Formation in the Sheep but concordant concordant 5B Bighorn Basin Basin (Fig. Several separate Fig 5B). separate but Bighorn zircons from tuff beds in the varievarie in the fission-track on fission track ages on ages mudstone interval within gated and purple the Little Sheep and gated purple b Heady, have been Chen 1989a, I989a b; 1992 Member have been obtained (Chen, Member Heady 1992; that and Tabott, 1992, pers pers. commun.). These dates suggest and Tabott 1992 commun suggest that of maximum pyroclastic in the upper an episode an deposition episode pyroclastic upper 128 Ma, Ma with Cloverly Formation Formation occurred between 118 and 128 Cloverly events around 1992 principal events around 120 120 and and 127 Ma (Heady, Heady 1992). principal two tuffaceous These two two events represented by by the two These events are are represented Reservoir sections mudstones and Alcova AIcova Reservoir mudstones in the Arminto and is the the fact that that in in Figure 3C. Consistent Consistent with these these dates is Figure 3C in the beds the purple purple and variegated beds in the Little Sheep Mudstone and variegated reversal of magnetic Member record record aa long Member magnetic polarity reversal long period period of reversal polarity to the M3 zone Swierc (1990) to the M3 reversal zone correlated by correlated Swierc 1990 polarity by scale (Fig. This period 6 This of the the Global Global Magnetic Magnetic Polarity scale of Fig 6). 123 126 Ma. Ma Based Based on on his his of reversal of reversal spans spans approximately 123-126 that the work 1990 concluded the paleomagnetic work, Swierc (1990) concluded that base paleomagnetic Member is about 128 Ma Ma and and of the Little Mudstone Member about 128 of the Little Sheep Sheep Mudstone the top is about about 116 I 16 Ma. Ma the top is that the Our the "Pryor Our correlations correlations suggest Pryor Conglomerate Conglomerate suggest that Wins Member" Formation, as identified Member of of the the Cloverly Formation as identified by Cloverly by Winsto low Heller (1987), is approximately time equivalent low and and Heller J 987 is approximately time equivalent to in the B interval conglomerate in the the Cloverly Formation in the B-interval conglomerate in Cloverly Formation 5B We the Wind River Basin (Fig. 5B). We conclude that their River Basin conclude that their the Wind Fig

j

,.

20

N

,.

\.....

j 130

M

'30

of the the Cloverly Formation re reAlthough the the absolute absolute age age of Although track age zir mains determinations on mains equivocal equivocal, fission fission-track age determinations on zircons of fine finecons from from pyroclastic pyroclastic facies and and magnetostratigraphy magnetostratigraphy of of grained facies facies permit permit tentative tentative interpretations interpretations. Samples of grained Formation the white to to green green tuffs tuffs in in the upper upper Cloverly Formation

"

50

M3

125

ESTIMATES ESTIMATES OF OF THE THE ABSOLUTE ABSOLUTE AGE AGE OF OF FACIES FACIES

\: T: I

I UO

5@

w

/-

N

Mn

Z 135

10

M

\35

." .""""""'" ."/' M

have been collected from outcrops at three sites within the Ar Maverick Springs Dome MS Wind River Basin

e

..

."

,

MIS

40

E

M16 .Ie

Ii

."

M17

M16 .Ie

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Morrison and and Cloverly Formations in in the the FIG 6.-Geochronology 6 of Morrison FIG. Cloverly Formations Geochronology of the Basin (Modified Modified from from Swierc, Swierc 1990 The left left column column isis the Bighorn 1990). The Bighorn Basin normal from Kent Kent and and Gradstein Gradstein (1985) 1985 showing time scale scale from geomagnetic showing normal geomagnetic time The center center column column shows shows magnetic cross hatched and and reverse reverse polarity. magnetic (cross-hatched) polarity The site for the the Cloverly and Morrison Morrison Formations Formations at at aa site reversal stratigraphy reversal stratigraphy for Cloverly and in the the northeastern northeastern Big Horn Basin. Basin in Big Horn

chert pebble conglom"Pryor conglom Pryor Conglomerate" Conglomerate actually actually isis aa chert-pebble erate within lower part of the Little Mudstone within the the lower of the Little Sheep erate Sheep Mudstone part the Cloverly Formation is is 6 The The base base of of the Member Member (Fig. Cloverly Formation Fig 6). an older older concon 20 m m below this conglomerate, where an about about 20 below this conglomerate where in the the subsurface subsurface (the the Pryor glomerate occasionally present present in Pryor glomerate isis occasionally I This lower in Figure I). This lower conglomerate Conglomerate in crops conglomerate crops Conglomerate Figure

southeastern Bighorn Basin Note Note that that to northeast northeast cross section section X-X" X X from from the the northwestern northwestern Wind Wind River River Basin Basin to to the the southeastern FIG. 5.-(A) FIG 5 A Southwest Southwest to Bighorn Basin. section location location shown shown on Figure in the the Kcv Kcv (uc) or C-interval C interval in in the the southeastern southeastern Bighorn Basin Cross Cross section the are in Basin. 2.2 the chert-bearing chert bearing conglomerates Figure Bighorn conglomerates X from from the Basin to to near the Cloverly of is shown on 5B. (B) South to north cross section X"_X'" southeastern Bighorn Basin the type Explanation of symbols is shown 58 B South to north cross section X the southeastern near type Bighorn Cloverly symbols Explanation in the the in the and B-intervals B intervals near the type section as as in section northeastern Bighorn Basin Chert-bearing Chert bearing conglomerates are in the Kcv Kcv (Ie) Ie or AA and near the section in in the the northeastern type section Bighorn Basin. conglomerates are River to Swierc's Swierc s (1990) shown in in the the column column to theright of the theBig HornRiver northwestern Wind northwestern Wind River River Basin. Basin Their Their relationship 1990 magneostratigraphy to the relationship to magneostratigraphy isis shown rightof Big Horn American StratiStrati from American section. section On On this this column column periods of normal normal polarity are represented cross hatched pattern. represented by by cross-hatched pattern Lithology Lithology on geophysical geophysical logs logsfrom periods of polarity are of Moberly to the the A A interval; interval Winslow Winslow and and Heller's Heller s (1987) graphic Company and Mills (1956). The Pryor Conglomerate of (1960) corresponds to Pryor and Mills The 1960 1987 Pryor Conglomerate Moberly corresponds graphic Company 1956 Pryor wellThe The upper LittleSheep Mudstoneof ofMoberly betweenthe theBBconglomerate Conglomerate to the the B B interval interval in in the the East East Lamb Lamb well. 1960 isis between conglomerate upper Little Sheep Mudstone Moberly(1960) Conglomerate corresponds corresponds to the"rusty of the the East East Lamb Lamb well well correlate correlate with withthe the Himes Himes Member Member of of Figure 6 The The thick thick sandstone sandstone above above the and The and the the "rusty beds The "rusty beds of rusty Figure6. rusty beds." rusty beds" referred to the Sykes Mountain Formation Formation in in the the northeast northeast Bighorn Basin beds" beds in in the the East East Lamb Lamb well well is is referred to as as the Sykes Mountain Bighorn Basin. cross

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T MAY ET MICHAEL ET AL. AL MICHAEL T.

the Cloverly Fonnation in the Formation in out at the the type type section section of of the the to the northern northern end end of of the the Bighorn Bighorn Basin and and is equivalent the equivalent to A interval conglomerate of the the western Wind River Basin. Basin western Wind A-interval conglomerate of out at

PALEOGEOGRAPHIC RECONSTRUCTION-TECTONIC TECTONIC PALEOGEOGRAPHIC RECONSTRUCTION AND PROVENANCE LMPLICATIONS IMPLICATIONS AND

A and western and B-interval B interval conglomerates in the the western Cloverly Awell the East Lamb well conglomerates in conglomerate is also present present in the Wind River Basin Basin were northeastward Wind generally northeastward were transported of thc the Bighorn Ba transported generally Ba(Fig. 5B). Along the the northeast northeast margin of Fig 5B Bighorn as were were C-interval C intervaI conglomerates eastern Wind Wind River River in the the eastern interval conglomerate occurs to a sin sin, the the B B-interval whitish as occurs lateral to a whitish conglomerates in 7 cf others 1992 Basin (Fig. 7; cf. May, 1992a, b; Meyers and others, 1992; 1992a b and tuff bed that concluded was at Fig tuff bed that Heady (1992) concluded was deposited at about 1992 May Meyers 1960 The C-interval C interval trunk trunk river river system extended event to 128 to the Curry 1960). 128 Ma Ma. We We correlate correlate this this pyroclastic pyroclastic event lower Curry, the lower system extended re the southeastern Bighorn Basin Basin near Ten Sleep as reinto the River Basin (Fig. 4 near Ten white Sleep as white to to green green tuff tuff bed bed in the the Wind Wind River Fig 4). flected the thick in that area by the relatively thick conglomerate in that area (Fig. flected date The conglomerate Fig of 128 128 Ma Ma represents represents the the best available estimate The date of this younger 5 Major tributaries of of this trunk system of system probably ofthe younger trunk of the the minimum minimum age age of the youngest youngest "Pryor Conglomerate" 5). Pryor Conglomerate not exist in the western part of River Basin. exist in the western the Wind Wind River Basin did not B intervaI conglomerate part of the (B-interval conglomerate) and very very likely is a a minimum age age that both in exex this and in Evidence for this is that in both the subsurface and the Wind River Basin for interval conglomerate in the as Basin as for the the BB-interval tensive in westernmost part of the of the basin no in the westernmost the basin, no tensive outcrop well outcrop part well. channelized or conglomerates exist channelized sandstone or exist in in the the C-inC in track ages fine Fission of conglomerates Fission-track ages of of tuffs tuffs and and magnetostratigraphy of finemagnetostratigraphy terval Little Popo the Little Agie except for aa single locality locality along along the Popo Agie grained facies facies in in the the Cloverly Cloverly Formation Fonnation aid in in constraining grained constraining terval except of Lander, Wyoming. Instead of River southeast southeast of Lander Instead of widewide the the forefore Wyoming of multiple multiple conglomeratic conglomeratic intervals within the the ages ages of spread of chert-pebble chert pebble conglomerate, sedimen our land basin basin. Such temporal temporal constraints are to our are relevant to spread deposition deposition of conglomerate sedimentation in in the western part of the the time of of the the western the basin basin during time of tectono part tectono-stratigraphic and paleogeographic reconstruction and reconstruction during stratigraphic paleogeographic is of the the eastern eastern C-interval C interval chert-pebble chert pebble gravels associated gravels is fore- deposition of associated with with early subsidence subsidence and and infilling of of the the fore a brown represented mainly by a gray and light-brown smectitic and land basin to basin correlight basin. We We are are confident in our basin-to-basin our basin corre gray interval below the the "rusty beds These mudmud These lations of sandstones rusty beds." sandstones and conglomerates conglomeratcs because paleo- mudstone interval because paleo stones lakes in extensive playa lakes. stones probably accumulated accumulated in extensive of non channelized probably magnetic and and absolute age age-dating of non-channelized facies playa dating of the the lowennost lowermost fluvial fluvial systems as Our previous show that lacustrine lithofacies previous studies of systems asthat distinctive pedogenic pedogenic and lacustrine in the western sociated with deposition of the chert gravels in the western of at occur from the deposition gravels occur at similar similar chronostratigraphic chronostratigraphic positions positions from the Wind River River Basin suggest Wind on a a broad broad braid braid plain, as previously discussed suggest deposition deposition on plain Bighorn to to the the Wind Wind River River Basins Basins as Bighorn previously discussed. with locally thick in with thick channel channel belts belts (A-interval A interval deposition in Channelized facies are discontin locally deposition Channelized sandy sandy /gravelly facies are inherently discontingravelly inherently 8 to B in 8) to meandering systems (B-interval deposition in Fig. Fig. intervaI uous uous, therefore therefore aa benchmark benchmark for for identifying identifying their their stratistrati Fig meandering systems deposition Fig Both systems 8) (May, 1992b; Meyers and others, 1992). Both systems is attainable only by graphic position position and and age age is attainable only graphic by mapping mapping and 8 May I992b Meyers and others 1992 apparently were controlled 1992b; were structurally controlled (May, I992b Meyof associated finedating the lateral and vertical distribution the lateral and vertical distribution ofassociated fine apparently structurally May Mey dating ers Northward ers and and others, others 1992). 1992 Northward to to northeastward northeastward dispergrained facies and ash beds. facies and ash beds disper grained 10 million occurred about sal sal of of sediment sediment occurred about 10 million years later apyears later, ap Absolute Absolute Age Age Differences Differences Among Among AA-, B-, B to 150-km 150 km to to the east east (C-interval 50 to C intervaI deposition). proximately 50 deposition and C Interval Conglomerates and C-Interval Conglomerates was via Transport via a a complex of mostly braided rivriv system of Transport was complex system mostly braided ers The The courses have been been strucstruc ers. courses of of these these rivers rivers also also may Estimates may have Estimates of of the the differences in in absolute absolute age age of of the CloClo controlled Syndepositional faults revealed revealed by our to calculation turally controlled. rate turally verly conglomerates conglomerates are important to are important calculation of of the rate Syndepositional faults by our verly 4B 5A on Figure subsurface correlation 4B, SA) and shown on correlation (Figs. and shown at west Figure at which which the the major major Cloverly Cloverly trunk trunk rivers rivers migrated migrated from from west Figs 7 regional dikes in in 7, and trends (Thomas, and dikes Thomas 1971), 1971 to regional lineament trends to east east through through the the foreland foreland basin basin. The The chronostratigraphy chronostratigraphy rocks the Wind and the basement rocks of the Wind River Range (Worl and the basement Worl and regional regional correlations correlations we we have have presented presented permit pennit aa first first and Range others, others 1986) 1986 all all are are subparallel and coincident coincident with with the the approximation of of these these age age differences differences. subparallel and approximation B interval margins of the major trunk systems (i.e., Aand B-interval of the trunk i e A and the A B Aand B-interval conglomerates are difAlthough the interval dif margins major systems Although conglomerates are the Wind Wind River River Basin Basin (May, May ficult to to separate separate temporally temporally, deposition deposition of both may may have have conglomerates) ficult of both conglomerates throughout throughout the b and 1992a, b; Meyers and others, 1992) suggesting I992a others 1992 structural ended by by 128 128 Ma Ma, but but no no later later than than 122 122 Ma. ended Ma This This is is based based Meyers suggesting structural control on on these these systems. on correlations correlations of of the the conglomerates conglomerates and and mudstones from control on mudstones from systems Stokes, Several Several workers workers (e.g., e g Stokes 1944, 1944 p. 980 McGookey Basin the Wind Wind River River Basin Basin to to the the section section in in the the Bighorn Bighorn Basin the p 980; McGookey and others, Heller and and others 1972; 1972 HeUer Heller and and others, others 1988; 1988 Heller and Paola, Paola stra where Swierc Swierc 1990 (1990) has has established established aa paleomagnetic paleomagnetic strawhere 1989) have concluded that chert gravels in the Cloverly 1989 have concluded that chert in the the BB-interval tigraphy (Fig. 5B). A A minimum minimum age age of of the interval concon gravels Cloverly tigraphy Fig 5B Formation were were derived derived from from basin-margin basin margin sources sources located located glomerate appears appears to to be be 128 Ma, based based on on the the youngest youngest Fonnation 128 Ma glomerate directly west or or southwest southwest of of the the Wind Wind River River Basin. Basin HowHow contrast directly west fission-track ages for for white white to to green green tuff tuff beds beds. In In contrast, fission track ages in Fonnaever, chert-bearing in the the Ephraim Forma ever chert bearing conglomerates our correlations in Figures 4 and 5, the Caccording to to 4 5 our correlations in and the C conglomerates Ephraim according Figures of the the Gannett tion of Gannett Group in far far western western Wyoming differ interval conglomerate conglomerate in the the eastern eastern Wind Wind River River Basin was tion interval Basin was Group in Wyoming differ For in composition from the conglomerates of the Cloverly in from of C-interval deposition, deposited during the final stage the of the of the C interval deposition composition Cloverly Forstage conglomerates deposited during in the Wind River Basin (Lammers, 1939; May, mation mation in the Lammers roughly corresponding to the 118-115 Ma interval of time to the I I 15 Ma Wind River Basin 1939 18 interval of time May roughly corresponding 1991, 1992b 1992b, 1993). Red 1991 chert grains are from MO MO, or or the the Cretaceous Cretaceous quiet quiet zone zone, to near the the base from to near base 1993 Red chert and pebbles grains and pebbles are abundant in the Ephraim conglomerates, whereas abundant in of the Sykes Mountain Fonnation or "rusty beds" (Fig. 6). of the Sykes Mountain Formation or rusty beds the Ephraim conglomerates whereas light-and light and Fig 6 dark-gray chert and and a and a a near near absence of four four and a maximum of 13 Consequently, aa minimum minimum of maximum of dark gray chert absence of of red red chert chert typify the 13 Consequently typify the of the Cloverly Forextra-basinally derived conglomerates million years years may may have have elapsed elapsed between between the the time time of of deextra For million de derived of the basinally conglomerates Cloverly mation of of BB-interval conglomerates in in the the western western Wind Wind mation of the the Wind Wind River both the the position of interval conglomerates River Basin. Basin Consequently, position Consequently both eastern Wind not dede in the the eastern River Basin Basin and and C C-interval conglomerates in Ephraim River intervaI conglomerates Wind and lower lower Cloverly were not Ephraim and Cloverly conglomerates conglomerates were River Basin Basin (Fig. 3C). rived from same source. River rived from the in the the the same source However, However conglomerates Fig 3C conglomerates in

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in FIG 7 sandstones in in the the Wind River River Basin. Basin Solid Solid arrows direction as as inFIG. 7.-Isopach map of of Cloverly conglomerates/sandstones arrows represent mean paleoflow Isopach map Cloverly conglomerates represent mean paleoflow direction in northwestern northwestern corner corner of map and by Meyers and others others (1992) for area southeast of of Riverton. Riverton Rose Rose diagrams tepreted by by May (l992a, b b) for for area area in area southeast tepreted May l992a map by Meyers 1992 for diagrams in this this north northeast corner corner of of the the map of trough'axis orientations in in Cloverly C conglomerate documented in of Waltman Waltman in in northeast north of as documented map represent represent dispersion dispersion of trough axis orientations Cloverly C conglomerate as movement on faults is is shown shown by U for for up and (D) D for for down. down study. Relative Relative dip-slip steep faults on steep study dip slip movement by (U) up and

western Wyoming resemble those of Bechler Formation in Bechler Formation in western of Wyoming resemble those could Cloverly Formation in in composition and possibly Cloverly Formation composition and possibly could have shared have common provenance. shared a a common provenance Although time of conglomeratic units in in the the Although time equivalence equivalence of conglomeratic units Gannett Group Group from near the Wyoming-Idaho border Gannett from near the Wyoming Idaho border and and in the the Wind River Basin Basin those in the the Cloverly Formation in Wind River those in Cloverly Formation has not yet been firmly established, we believe the major established believe the has not been we major yet firmly in the fluvial and those in the fluvial systems the Ephraim Formation and those in the systems in Ephraim Formation Wind River Cloverly Formation in the Wind Basin represent sepFormation in the River Basin represent sep Cloverly arate arate drainage systems, at least through much of of NeocomNeocom drainage systems at least through much 130 Ma In the ian time (i.e., until about 130 Ma). In fact, the Ephraim until about fact ian time Le Ephraim Formation may be older than the lower Cloverly conglomFormation may be older than the lower Cloverly conglom erates in Wind River erates in the the Wind River Basin. Basin Ephraim fluvial systems systems Ephraim fluvial the Wind River Basin have been interpreted directly west west of the River Basin have been of Wind interpreted directly by Derman and and others others (1984) as northward-flowing northward flowing trunk trunk I984 as by Derman is consistent with our interpretation. river which which is consistent with river systems our interpretation systems

the the

DISCUSSION DISCUSSION AND AND CONCLUSIONS CONCLUSIONS

The in central central Wyoming contains The Cloverly Formation in Wyoming contains Cloverly Formation at three chert-pebble chert pebble conglomerates three distinct distinct stratigraphic stratigraphic conglomerates at intervals. intervals Each Each Cloverly separate Cloverly conglomerate conglomerate represents represents aa separate central at difdif that accumulated in central Wyoming belt belt of of gravel that accumulated in Wyoming at gravel A and B intervaI and and upper ferent ferent times. times Both Both the the lower lower (Aand B-interval) upper (C-interval) C interval conglomeratic reflect aa northerly-to northerly to conglomeratic deposits deposits reflect Pa northeasterly-dipping paleoslope in central Wyoming. in central Wyoming Panortheasterly dipping paleoslope and leogeographic reconstruction based based on on paleocurrent leogeographic reconstruction paleocurrent and to outcrop mapping of subsurface subsurface to thickness of ofsandstones sandstones outcrop mapping of thickness and and conglomerates others 1992) 1992 I992a b; b Meyers and others, conglomerates (May, May 1992a, Meyers and A and indicates indicates northward northward to to northeastward northeastward transport of the the Aand transport of The B-interval B intervaI gravels Basin The into the the southwestern southwestern Bighorn Bighorn Basin. gravels into into the the C-interval C interval gravels were transported northeastward into gravels were transported northeastward southeastern southeastern Bighorn Basin Bighorn Basin. and subsurface ofthe the nonCorrelation of surface surface and subsurface sections sections of non Correlation of marine marine Morrison-Cloverly Morrison Cloverly interval interval throughout throughout Wyoming Wyoming

108 108

ET AL MICHAEL T MAY ET MICHAEL T. AL.

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diagrams showing the paleogeography paleogeography of diagrams showing the A , B-, B to western Wind Wind River River Basin Basin region Cloverly Aregion during during Cloverly and interval deposition and C C-interval deposition. Inferred Inferred location location of of horst horst and and graben systems graben systems is section interpretation 5 and the corre is based based on on cross cross-section interpretation (e.g., Figs. 4 4, 5) corree g Figs spondence between between isopach isopach and and paleocurrent paleocurrent trends trends as as inferred inferred from Figspondence Fig Jines and Pre ure 77. Active Active faults faults shown shown with with solid solid lines and inactive inactive are dashed dashed. Prethose in sumably not not all all fault fault systems systems in in the the east east were active active as early in sumably early as those the west west. the the the central central

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early structural structural partitioning partitioning in in the Sevier fore foreearly land basin basin controlled controlled formation fonnation thicknesses thicknesses and and the the location location land of thick thick sandstone sandstone bodies bodies of

deposited in trunk rivers rivers. Prein trunk Pre deposited occurred over Cloverly erosion erosion of of Morrison Morrison sediments sediments occurred over NE NECloverly trending horst blocks, and the axes of thick channel deposits horst blocks and the axes of thick channel trending deposits in the the Cloverly Cloverly Formation Formation parallel parallel nearby nearby NE NE-trending in faults trending faults these mapped in in underlying underlying rocks rocks. Recurrent Recurrent movement movement along along these mapped NE-trending faults controlled controlled dispersal dispersal of of coarse coarse detritus in NE detritus in trending faults Cloverly channels in the Wind River Basin (May, 1992a, channels in the Wind River Basin 1992a Cloverly May b; Meyers Meyers and and others others, 1992 1992). b The elapsed elapsed time time between between A A-interval interval conglomerate de The conglomerate deWind River Basin position in the western Wind River Basin and C-interval in the western and C interval position conglomerate deposition deposition in in the the eastern eastern Wind Wind River River Basin Basin conglomerate sed implies aa complex complex history history of of early early basin basin subsidence, subsidence sedimplies iment-filling, and local local reworking reworking of of fluviaJly deposited iment filling and f1uvially deposited coarse-grained clastic sediment sediment. Depocenters Depocenters associated with coarse associated with grained clastic trunk river river systems systems appear appear to to have have migrated migrated from west to to trunk from west east east through through time time. "Rusty beds" transgression transgression over over the the non nonRusty beds

in the the northeast, northeast marine Cloverly section probably probably began in toward the the southwestern the Wind River then spread toward southwestern part ofthe Wind River then part of Basin Assuming that that the major axis of had shifted Basin. axis of subsidence had shifted major to the east east during C-interval C interval conglomerate farthest to conglomerate depodepo sition this area was the first first to to be be transgressed was presumably the sition, this area transgressed However once the Cretaceous seaway our study area. area However, once by the seaway in our the rivers in which which the C-interval C interval conglomerates were de the were deconglomerates drowned time were drowned, short period of of time posited were aa relatively short as little little as as one one million before sandy million years) elapsed sandy elapsed (perhaps perhaps as years before and muddy marine to transitional facies spread across marine to transitional marine facies and spread across Thus structural the area area to to the western western part of structural the Wyoming Thus, part of Wyoming. control on on Cloverly river river systems also influenced influenced control systems probably probably also the initial initial location of estuarine estuarine and and eventually marine marine facies facies the across the Wind Wind River Basin region (cL cf Kvale and and Vondra, Vondra across 1993 1993). Rivers transporting the Ephraim For transporting gravels gravels making making up up the Ephraim Fornot flow flow into the the Wind Wind River River Basin Basin mation probably did not area on our Based on our outcrop and area during Cloverly deposition. outcrop and deposition Based and regional re subsurface correlations and regional paleogeographic paleogeographic reand previous construction studies (May, 1992b construction and previous provenance provenance studies May 1992b, not 1993), we 1993 we conclude that that Cloverly sediments also also were were not Cloverly sediments west of site of likely reworked from sources directly west the site of sources of the likely directly to have occurred, deposition foreland basin. basin For For this this to occurred deposition in the foreland the would have have had had to to have from the Cloverly Cloverly would have been been reworked reworked from isostati foredeep deposits (Gannett Group), as they were isostatiGannett as were deposits Group they then and then cally uplifted after denudation denudation of of the the thrust-belt thrust belt and uplifted after shed eastward how eastward (Heller Heller and 1988 This model, model howshed and others, others 1988). ever, ies elasticity ever impl of the the lithosphere with no no structural implies elasticity of lithosphere with partitioning. Our work suggests that that the the lithosphere in this this work partitioning lithosphere in suggests region behave elastically because it contained not behave contained inin region did not elastically because herent structural structural weaknesses deeply in basement basement rocks. rocks deeply seated in Significantly, filled with with Cloverly have Significantly channels filled Cloverly gravels gravels have aa nearly axial orientation, trending subparallel rather than orientation than nearly trending subparallel to the structural grain belt orthogonal the structural the Sevier Sevier orogenic orthogonal to grain of the orogenic belt devel (Fig. Northeasterly-directed 9 Fig 9). Northeasterly directed drainage drainage apparently apparently developed or perhaps even earlier earlier oped during during Cloverly Cloverly deposition deposition or perhaps even during upper Morrison deposition; unfortunately, regional Morrison upper during deposition unfortunately regional Mor paleocurrent data for for the the channelized channelized deposits in the the Morpaleocurrent data deposits in are scarce. Sevier rison Formation Formation are scarce Presumably, the early early Sevier Presumably the foredeep was filled A and filled by the time time Aand B-interval B interval Cloverly Cloverly foredeep was by the Ba western Wind conglomerates accumulated in the western accumulated in the Wind River Baconglomerates above sin. sin The The younger C interval above younger Cloverly Cloverly conglomerates conglomerates (C-interval), the lavender lavender mudstone mudstone beds beds and and the white white to to dark-green dark green tuff~bearing of the study tuff bearing interval in in the eastern of area eastern part study area, part than the were perhaps derived derived more were perhaps more from the the south than the older, older western conglomerates (Awestern Progressively B intervals and B-intervals). Progressively conglomerates A and more southeasterly development of more fluvial trunk systems of fluvial trunk systems southeasterly development or more carrying chert gravels evolved in Wyoming for one or chert evolved in for one more carrying gravels Wyoming of of the the following extra-basinal I extra basinal tectonism tectonism may reasons (I) may following reasons: have migrated migrated temporally to south south along the baba have from north north to along the temporally from sin margin progressively elevating more southerly-located sin more located margin progressively elevating southerly source regions; 2 movement movement along intra-basinal basement source regions (2) along intra basinal basement faults might have been been recurrent recurrent and and migrated faults time might have migrated through through time to the the east east; or to or (3) a decrease 3 a decrease in in overall overall basin basin subsidence, subsidence coupled with with an an increase could have increase in in sediment sediment supply coupled supply could filled the the foreland basin, causing avulsion of major systems filled foreland basin avulsion of major systems causing preferentially in in aa direction direction parallel parallel to to and and down down paleoslope paleoslope preferentially (cr. Whatever cf Bridge Whatever the the and Leeder, Leeder 1979; 1979 Seni, Seni 1980). 1980 Bridge and cause, we we believe intra-basinal structural parbelieve that basinal structural cause that regional intra par regional titioning, manifested manifested as series of of subtle subtle horsts horsts and and graas a a series titioning gra

109 109

CRETACEOUS FORELAND CRETACEOUS CONGLOMERATES CONGLOMERATES IN IN THE THE WYOMING WYOMING FORELAND

Peter reviews of this manuscript. manuscript Peter orous and and constructive constructive reviews of this measured sections us graciously provided us measured sections and the Rattlesnake Rattlesnake Hills Hills and and Alcova AIcova other outcrop data and other data from from the foreland basin sedimentation sedimentation Reservoir Research on on foreland-basin Reservoir areas areas. Research in Wyoming is is supported by NSF NSF Grants Grants EAR-8709039 EAR 8709039 and and in We EAR 17775 to and Johnson are 90 Lee Suttner Gary Johnson. We are EAR-9017775 to Lee Suttner and Gary this to Kim Schulte for for typing multiple versions versions of of this indebted to indebted to members of of the the Graphics, and to manuscript and Graphics Cartography Cartography De and Photography of the the Indiana Indiana University Deand Photography Division Division of Sciences and the Indiana of Geological partment of Geological Sciences and the Indiana Survey Survey. orous

DeCelles also has DeCelles also has

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REFERENCES REFERENCES

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Tectonic development of Idaho ARMSTRONG F. F C. C AND AND ORIEL, ORIEL S. S S., S 1965 ARMSTRONG, 1965, Tectonic development of IdahoAssociation of Petroleum Geologists thrust belt: belt American Wyoming American Association of Petroleum Geologists Wyoming thrust Bulletin v. 49, 49 p. 1847 1866 p 1847-1866. Bulletin, American BALLY A. W 1987 Atlas Atlas of of Seismic Seismic Stratigraphy: Tulsa American A W., Stratigraphy Tulsa, BALLY, 1987, I Association of of Petroleum Petroleum Geologists Studies Studies in in Geology 27 v. I, Geology 27, Association 125 p. p 125 MCGREGOR A. A A., A 1966 Stratigraphy and petroBOLYARD D. D W. W AND AND MCGREGOR, petro Stratigraphy and BOLYARD, 1966, in northeastern leum potential of of Lower Lower Cretaceous Cretaceous Inyan Kara Group Inyan Kara Group in leum northeastern southeastern Montana Montana and and western western South Dakota American Wyoming southeastern Wyoming, South Dakota: American 2221 2244 Association of of Petroleum Petroleum Geologists Bulletin v. 50, 50 p. p 2221-2244. Association Geologists Bulletin, model of alluvial BRIDGE J. J S. S AND LEEDER M. M R., R 1979 A A simulation simulation model AND LEEDER, BRIDGE, 1979, of alluvial 26 p. 617 644 stratigraphy: stratigraphy Sedimentology, Sedimentology v. 26, p 617-644. Active tectonics and river BURNETT A. A W. W AND AND SCHUMM, SCHUMM S. S A., A 1983 Active BURNETT, 1983, tectonics and river 222 p. 49 50 in Louisiana Louisiana and and Mississippi: Science v. 222, p '49-50. response response in Mississippi Science, CHEN Z., Z 1989a A A fission-track fission track study of the the terrigenous sedimentary CHEN, 1989a, study of terrigenous sedimentary Formations in in the the northeastern northeastern of the the Morrison Morrison and and Cloverly sequences sequences of Cloverly Formations Thesis Dartmouth Dartmouth ColCol Basin Wyoming: M S Thesis, Bighorn Basin, Wyoming Unpublished Unpublished M.S. Hanover 66 66 p. lege, lege Hanover, p of the the terrigenous CHEN Z., Z 1989b A A fission-track fission track study terrigenous sedimentary sedimentary CHEN, 1989b, study of Morrison and Formation in in the the northeastern northeastern of the the Morrison and Cloverly sequences sequences of Cloverly Formation Ab of America America AbBasin Wyoming abs Bighorn Basin, Geological Wyoming (abs.): Geological Society Society of stracts with with Programs, 26 p. 206 stracts Programs v. 26, p 206. CONNER J. J L. L AND HATCH J. J E., E 1980 Stratigraphy of the the Sage AND HATCH, Valley CONNER, 1980, Stratigraphy of Sage VaJley Idaho and Elk Elk Valley quadrangles, western Wyoming and southeastern southeastern Idaho, and quadrangles western Wyoming and Hollis S., S of Wyoming: in Hollis, Geological in Stratigraphy Stratigraphy of Wyoming Casper, Casper Wyoming Wyoming Geological Association 31st 31 st Annual Annual Field Field Conference Conference Guidebook, Guidebook p. 263 277 p 263-277. Association CORMAN D., D 1972 Formation Formation of of aa mature mature siliceous siliceous chert chert conglomerate conglomerate CORMAN, 1972, Lower Cretaceous) Cretaceous of of the the Rocky Mountain foothills, foothills Alberta: Alberta UnpubUnpub (Lower Rocky Mountain lished M.S. M S Thesis, Thesis University of Delaware, Delaware Newark, Newark 73 73 p. p lished University of of Upper JurCURRY W. W H., H Ill, Ill 1960, 1960 Stratigraphy and paleogeography CURRY, Stratigraphy and paleogeography of Upper Jur assic and and Lower Lower Cretaceous Cretaceous rocks rocks of of central central Wyoming: Unpublished assic Wyoming Unpublished Ph D Dissertation, Dissertation Princeton Princeton University, Princeton 306 306 p. p Ph.D. University Princeton, DECELLES P. P G., G 1984 Sedimentation Sedimentation and and diagenesis in a tectonically tectonically DECELLES, 1984, diagenesis in Kootenai nonmarine foreland foreland basin: basin The The Lower LowerCretaceous Cretaceous Kootenai partitioned, partitioned nonmarine Ph D Dissertation, Dissertation Formation southwestern southwestern Montana: Montana Unpublished Formation, Unpublished Ph.D. Indiana University, 422 p. Indiana p University Bloomington, Bloomington 422 DECELLES P. P G., G 1986 Sedimentation Sedimentation in in a tectonically DECELLES, 1986, tectonically partitioned partitioned nonKootenai Formation, Formation marine foreland foreland basin: basin the the Lower Lower Cretaceous Cretaceous Kootenai marine of America, America v. 97, 97 p. 911 southwestern Montana: Montana Geological southwestern Geological Society Societyof p 911931 931. 1992 Nonmarine Nonmarinesedimentation sedimentation in in the the DECELLES P. P G. G AND AND BURDEN, BURDEN E., E 1992, DECELLES, basin Cordilleran foreland foreland basin: overfilled part of the the Jurassic-Cretaceous Jurassic Cretaceous Cordilleran overfilled part of Basin Morrison and and Cloverly Formations central central Wyoming, U S A Basin Morrison Cloverly Formations, Wyoming U.S.A.: Research v. 4, 291 313 4 p. Research, p 291-313. Jurassic DERMAN A. S WILKINSON, WILKINSON B. B H., H AND DORR J. J A., A Jr., Jr 1984, 1984 JurassicDERMAN, A S., AND DORR, United Cretaceous nonmarine nonmarine foreland toreland basin basin sedimentation sedimentation in inthe thewestern western United Cretaceous Bulletin States (abs.): abs American Association Association of ofPetroleum PetroleumGeologists States American Geologists Bulletin, 68 p. 470 471 v. 68, p 470-471. of western western Wyoming and southeastern southeastern EYER J. J A., A 1969 Gannett Gannett Group EYER, 1969, Wyoming and Group of Bulletin v. 3, 3 Idaho American American Association Association of of Petroleum Petroleum Geologists Idaho: Geologists Bulletin, 1368 1391 p. p 1368-139l. Jur FURER L. L C., C 1970, 1970 Petrology and stratigraphy ofnonmarine nonmarine Upper FURER, Petrology and stratigraphy of Upper Jursoutheastern assic Lower Cretaceous Cretaceous rocks rocks of of western western Wyoming and southeastern assic-Lower Wyoming and Association of ofPetroleum Petroleum Geologists Bulletin v. 54, 54 Idaho: Idaho American American Association Geologists Bulletin, 2282 2302 p. p 2282-2302. v

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for NeocomianNeocomian FIG 9 FIG. 9.-Regional Regional paleogeographic paleogeographic reconstruction for is inferred inferred to to become become younger the basin basin margin is Aptian time time. Thrusting younger Aptian Thrusting along along the Source areas for to fluvial systems. areas for to the the south south. Arrows Arrows indicate major major fluvial systems Source and C-interval C interval conglomeasternmost A interval conglomerates and easternmost A- and B B-interval conglom Nevada based based on on paleocurrent data data and and erates probably in Utah Utah or or Nevada erates were in probably were in southwestern southwestern Wyoming. the the "no chert-pebble no chert conglomerate region in Wyoming pebble conglomerate" data are Derman and others others (1984). Ephraim conglomerate dispersal data are from Derman 1984 Ephraim conglomerate are from from H. H T. T Pile Pile Dispersal data data in extreme southwestern Wyoming are in extreme Dispersal

(pers. commun pers commun.).

bens was bens, was mainly mainly responsible responsible for controlling controlling the geographic geographic chert pebble gravels and and their gedistribution distribution of of Cloverly chert-pebble ge trends ometry. interpretation is supported This interpretation supported by isopach isopach trends ometry This correlations of channel sand bodies and regional of channel sand bodies regional correlations. of foreland Evaluation modeling foreland basins basins Evaluation of of stratigraphic stratigraphic modeling of is limited an of complex basin stratigraan understanding basin is limited by understanding complex stratigra by the chronostratigphies. of the proper understanding understanding of chronostratig phies Without proper raphy in a basin, the applicability of quantitative in a basin the of tectonic raphy applicability quantitative tectonic, strati climatic, climatic or or eustatic eustatic models models in in predicting detailed straticannot be graphic within basins basins cannot be rigorously tested graphic sequences sequences within rigorously tested. two dimensional crustal crustal rheological models or or even even Broad, Broad two-dimensional rheological models, fill models models have have traditwo dimensional sedimentary basin-fill basin tradi two-dimensional sedimentary and anationally basis for for collecting ana formed aa satisfactory satisfactory basis collecting and tionally formed lyzing within foreland foreland basins. basins Our Our study data from from within sug study suglyzing data gests, that such such two-dimensional two dimensional basin basin models models however that gests however, should accommodate the the concept ofrecurrecur should be be modified modified to to accommodate concept of and the the comcom of foreland basins and rent rent structural of foreland basins structural partitioning partitioning plexity in the the resulting resulting stratigraphic stratigraphic sequences. sequences plexity generated generated in

ACKNOWLEDGEMENTS ACKNOWLEDGEMENTS

We to Peter Peter Schwanns, Schwanns Peter Peter We express express appreciation appreciation to DeCelles, Steve Dorobek Rod DeBruin DeBruin for for their their rigDeCelles Steve Dorobek and and Rod rig

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110 110 HEADY HEADY, EE., 1992 1992,

and Stratigraphic Stratigraphic and and fission fission track track study of of Morrison Morrison and S Cloverly sediments sediments, Bighorn County, Wyoming: M.S. Cloverly Bighorn County Wyoming Unpublished M Thesis Thesis, Dartmouth Dartmouth College College, Hanover Hanover, 52 52 p p.

R P HELLF S S H P J c., C HAGEN HELLER, P. L L., BOWDLER BOWDLER, S. S., CHAMBERS CHAMBERS, H. P., COOGAN COOGAN, J. HAGEN, W S AND LAWTON T W. S S., SHUSTER SHUSTER, M M. W W., WINSLOW WINSLOW, N N. S., AND LAWTON, T. F F., 1986 1986, Time Time of of initial initial thrusting thrusting in in the the Sevier Sevier orogenic belt belt, Idaho Idaho-Wyoming Wyoming and 14 p 391 and Utah Utah: Geology Geology, v. 14, p. 388 388-391. HELLER 1988 Two-phase Two phase HELLER, PP. L L., ANGEVINE ANGEVINE, C C. L L., AND AND WINSLOW WINSLOW, N N. SS., 1988, basin sequences 16 p. stratigraphic model model of of foreland foreland-basin sequences: Geology Geology, v. 16, stratigraphic p 501 504 501-504. HELLER HELLER, PP. L L. AND AND PAOLA PAOLA, C c., 1989 1989, The The paradox of of Lower Lower Cretaceous Cretaceous United gravels and and the the initiation initiation of of thrusting in in the the Sevier Sevier orogenic belt belt, United gravels of America States Bulletin v. States Western Western Interior Interior: Geological Geological Society of America Bulletin, 875 101 101, pp. 864 864-875. of the HOOPER HOOPER, W W. FF., 1962 1962, Lower Lower Cretaceous Cretaceous stratigraphy stratigraphy of the Casper Arch Arch, eds Wyoming, in in Enyert Enyert, R R. L L., and and Curry Curry, W W. H H., eds., Symposium on on Wyoming Early Cretaceous Cretaceous Rocks Rocks of of Wyoming Wyoming and and Adjacent Adjacent Areas Areas: Casper Casper, WyEarly Wy Guide oming Geological Geological Association Association 17th 17th Annual Annual Field Field Conference Conference Guideoming book 147 book, pp. 141 141-147. KENT Cretaceous and KENT, D D. V V. AND AND GRADSTEIN GRADSTEIN, FF. M M., 1985 1985, A A Cretaceous and Jurassic Jurassic 1419 geochronology: Geological Geological Society of of America America Bulletin Bulletin, v. 96 96, pp. 1419geochronology 1427 1427. KNIGHT Cadomin unconformity KNIGHT, R R., 1978 1978, Deposition Deposition on on the the pre pre-Cadomin unconformity surface surface in central Alberta S Thesis in north north-central Alberta: Unpublished Unpublished M M.S. Thesis, Queen Queen's Univer Univer92 pp. sity, Kingston Kingston, 92 sity KVALE KVALE, EE. PP., 1986 1986, Paleoenvironments Paleoenvironments and and tectonic tectonic significance of of the the Lower Cretaceous Formations Upper Jurassic Jurassic Morrison Morrison/Lower Cretaceous Cloverly Formations, Upper D Dissertation Bighorn Basin Basin, Wyoming Wyoming: Unpublished Unpublished Ph Ph.D. Dissertation, Iowa Iowa State State Bighorn University, Ames Ames, 191 pp. University KVALE controlled sedimentalion sedimentation KVALE, EE. PP. AND AND BECK BECK, R R. A A., 1985 1985, Thrust Thrust-controlled patterns of of the the earliest earliest Cretaceous Cretaceous nonmarine nonmarine sequence sequence of the the Montana Montanapatterns Idaho abs Idaho-Wyoming Sevier foreland foreland basin basin (abs.): Geological Society of of Wyoming Sevier America 636 America Abstracts Abstracts with with Programs Programs, v. 17 17, p p. 636. KVALE level KVALE, EE. PP. AND AND VONDRA VONDRA, C C. FF., 1993 1993, Effects Effects of of relative relative sea sea-level changes and and local local tectonics tectonics on on aa Lower Lower Cretaceous Cretaceous fluvial fluvial to to transi transichanges tional tional marine marine sequence sequence, Bighorn Bighorn Basin Basin, Wyoming Wyoming, USA USA, in in Marzo Marzo, M M. and and Puigdefabregas Puigdefabregas, C c., eds eds., Alluvial Alluvial Sedimentation Sedimentation: Oxford Oxford, In International ternational Association Association Sedimentologists Sedimentologists Special Publication Publication 17 17, p. 383p 383 399 399. LAMMERS of the LAMMERS, EE. C C. H H., 1939 1939, The The origin origin and and correlation correlation of the Cloverly Cloverly 132 conglomerate: Journal Journal of of Geology Geology, v. 47 47, pp. 113 I 13-132. conglomerate LOVE LOVE, JJ. D D., 1948 1948, Mesozoic Mesozoic stratigraphy stratigraphy of of the the Wind Wind River River Basin Basin, cen central tral Wyoming Wyoming, in in Maebius Maebius, JJ. BB., ed ed., Wind Wind River River Basin Basin: Casper Casper, Wy Wyoming Geological Geological Association Association Third Third Annual Annual Field Field Conference Conference Guide Guideoming book 111 and book, pp. 96 96-111 and plate plate in in pocket pocket. MAY MAY, M M. T T., 1991 1991, Architectural Architectural analysis analysis of of Lower Lower Cretaceous Cretaceous fluvial fluvial systems, an ajd aid in in tectonostratigraphic tectonostratigraphic study study in in the the central central portion portion of of systems developing foreland foreland, northwestern northwestern Wind Wind River River Basin Basin, Wyoming Wyoming (abs.): aa developing abs Geological Society Society of of America America Abstracts Abstracts with with Programs Programs, v. 23 23, pp. 285 285Geological 286 286. MAY basinal tectonism MAY, M M. T T., 1992a 1992a, Intra Intra- and and extra extra-basinal tectonism, climate climate and and in intrinsic trinsic threshold threshold cycles cycles as as possible possible controls controls on on Early Early Cretaceous Cretaceous fluvial fluvial architecture architecture, Wind Wind River River Basin Basin, Wyoming Wyoming, in in Mullen Mullen, C C. EE., ed ed., Re Rediscover discover the the Rockies Rockies: Cheyenne Cheyenne, Wyoming Wyoming Geologica Geological Association Association 43rd 43rd Annual 74 Annual Field Field Conference Conference Guidebook Guidebook, p p. 61 61-74. MAY MAY, M M. T T., 1992b 1992b, A A regional regional tectono tectono-stratigraphic analysis of of the the Late Late stratigraphic analysis Jurassic-Early Cretaceous Cordilleran Cordilleran foreland foreland basin basin, Wind Wind River River basin basin Jurassic Early Cretaceous region, Wyoming Wyoming: Unpublished Unpublished Ph Ph.D. Dissertation, Indiana Indiana Univer UniverD Dissertation region sity, Bloomington Bloomington, 308 308 pp. sity MAY MAY, M M. TT., 1993 1993, Petrographic Petrographic characteristics characteristics of of Morrison Morrison-Cloverly Cloverly Formations Formations and and equivalent equivalent rocks rocks in in west west central central and and central central Wyoming Wyomingfor tectonic in the Sevier Implications for tectonic complexity in the early Sevier foreland, in foreland in complexity early Implications Keefer Keefer, W W. R R., Metzger Metzger, W W. JJ., and and Goodwin Goodwin, L L. H H., eds eds., Oil Oil and and Gas Gas and and Other Other Resources Resources of of the the Wind Wind River River Basin Basin: Cheyenne Cheyenne, Wyo Wyo70 ming Geological Geological Association Association Special Special Symposium Symposium, pp. 49 49-70. ming MCGooKEY MCGOOKEY, D D. PP., HAUN HAUN, JJ. D D., HALE HALE, L L. A A., GOODELL GOODELL, H H. G G., MCCUB MCCUB BIN, D D. G G., WEIMER WEIMER, R R. JJ., AND AND WULF WULF, G G. R R., 1972 1972, Cretaceous Cretaceous Sys SysBIN tem tem, in in Mallory Mallory, W W. W W., ed ed., Geological Geological atlas atlas of of the the Rocky Rocky Mountain Mountain region: Denver Denver, Rocky Rocky Mountain Mountain Association Association of of Geologists Geologists, pp. 18989 region 228. 228 MEYERS, JJ. H H., SUTTNER SUTTNER, L L. JJ., FURER FURER, L L. c c., MAY MAY, M M. T T., AND AND SO SoMEYERS REGHAN, M M., 1992 1992, IntrabasinaI Intrabasinal tectonic tectonic control control on on fluvial fluvial sandstone sandstone REGHAN v

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bodies in in the the Cloverly Formation Formation (Early Cretaceous west-central west central Wybodies Early Cretaceous), Wy U S. S A Basin Research, Research v. 4, 4 p. 315 333 oming U. oming, A.: Basin p 315-333. MILLS For K 1956 Subsurface Subsurface Stratigraphy of of the the Pre-Niobrara Pre Niobrara ForMILLS, N N. K., 1956, mations in in the the Big Committee Horn Basin in Nomenclature Nomenclature Committee, mations Basin Wyoming, Big Hom Wyoming in eds Associa eds., Wyoming Stratigraphy: Stratigraphy Casper, Casper Wyoming Geological Geological Association 98 tion, 98 p. p MIRSKY A 1962 Stratigraphy of non-marine Jurassic and and Lower Lower non marine Upper MIRSKY, A., 1962, Stratigraphy of Upper Jurassic Cretaceous rocks southern southern Big Horn Mountains, Mountains Wyoming: American Cretaceous rocks, Big Horn Wyoming American Association of Petroleum 1680 Petroleum Geologists BUlletin, Bulletin v. 46, 46 p. 1633 Association p 1633-1680. MOBERLY R., R JR., JR 1960 Morrison, Morrison Cloverly, and Sykes Mountain ForFor MOBERLY, 1960, Cloverly and Sykes Mountain mations northern northern Bighorn Basin Wyoming and and Montana: Montana Geological mations, Bighorn Basin, Geological Bulletin v. 71, 7 I p. 1136 1176 Society of America Bulletin, p 1136-1176. PALMER A R 1983 The The decade decade of of North American American geology 1983 1983 geoPALMER, A. R., 1983, geo scale Geology, 503 504 v I I p. logic time scale: II, logic time Geology v. p 503-504. PETERSON J. J A., A 1972 The The Jurassic Jurassic System, in Mallory, W W., W ed PETERSON, 1972, ed., System in Mallory W. the Rocky Mountain Region: Denver Rocky Moun Geologic Atlas of the Rocky Mountain Region Denver, Rocky Mountain Association of of Geologists, 176 185 tain Association Geologists p. p 176-185. Russ D. D P., P 1982 Style and significance of of surface surface deformation deformation in in the the Russ, 1982, Style and of New Madrid, United Stales States Madrid Missouri: Missouri Washington, D c., C United vicinity of Washington D. Professional Paper 1236-H, 1236 H p. 95 114 Geological Survey Professional p 95~114. SCHULTHEIS H 1970 Petrography, and origin of the the Cadomin Cadomin SCHULTHEIS, N N. H., 1970, source and Petrography source origin of and AthAth Cretaceous between between the Saskatchewan and the North Saskatchewan conglomerate (Cretaceous) abasca rivers Alberta: Thesis McGill McGill University, Alberta Unpublished M S Thesis, abasea rivers, University Unpublished M.S. Montreal 133 p. Montreal, 133 p basin SCHWARTZ R K AND DECELLES, DECELLES P. P G., G 1988 Cordilleran Cordilleran foreland foreland basin SCHWARTZ, R. K. AND 1988, evolution and and synorogenic sedimentation sedimentation in in response interactive CreCre to interactive evolution response to taceous and reactivated reactivated foreland foreland partitioning, in Schmidt, Schmidt C. C taceous thrusting and partitioning in J and W J., J eds Interaction of the the Rocky Fore J., and Perry, R. W. eds., Interaction Mountain ForePerry R Rocky Mountain of land Belt Boulder, Boulder Geological land and the the Cordilleran Thrust Belt: Geological Society Society of America 171 p. 489 514 America Memoir Memoir., 171, p 489-514. SENI J 1980 Sand body geometry SENI, SS. J., 1980, Sand-body geometry and depositional depositional systems, systems OgalOgal laha Formation Texas: Texas Austin, Austin Texas Bureau of Economic Geology laha Formation, of Economic Geology No 105 Report of Investigations 105, 35 35 p. Report Investigations No. p STOKES 1944 Morrison Formation in and and STOKES, W W. L L., 1944, Formation and and related related deposits in to the Colorado Plateau of America America BulBul adjacent to the Colorado Plateau: Geological adjacent Geological Society Society of letin 55 p. 951 992 letin, v. 55, p 951-992. SWIERC E 1990 The timing of Jurassic to to Earliest Cretaceous Cretaceous SWIERC, JJ. E., 1990, of Latest Jurassic nonmarine Basin Wyoming: nonmarine sedimentation sedimentation, northeastern Bighorn Bighorn Basin, Wyoming Thesis DartDart M S Thesis, Magneto-stratigraphic Magneto stratigraphic implications: implications Unpublished Unpublished M.S. mouth mouth College College, Hanover Hanover, 156 156 p. p THOMAS G E 1971 Continental tectonics southwest Wyoming THOMAS, G. E., 1971, Continental plate plate tectonics: Wyoming in Renfro Renfro, A. Symposium in A R., R ed., ed Tectonics and and Their Their Symposium on Wyoming Wyoming Tectonics Association 23rd 23rd Economic Significance Significance: Casper, Wyoming Geological Economic Casper Wyoming Geological Association Annua Field Conference Conference Guidebook 103 123 Annual Field Guidebook, p. p 103-123. THOMPSON T 1984 Limestone-clast Limestone clast conglomerate in the Cre THOMPSON, T. A A., 1984, the Early conglomerate in Early Cretaceous basin in taceous foreland basin in southwestern southwestern Montana: Montana Origin signifi Origin and signifiThesis Indiana University, cance: Unpublished Unpublished M M.S. cance S Thesis, University Bloomington, Bloomington 73 p p. WAAGE K M., M 1959 Stratigraphy of the the Inyan Kara Group in the the Black B ack WMGE, K. 1959, Stratigraphy of Inyan Kara Group in Hills United Hills: States Geological Survey Bulletin p. 11-90. United States Bulletin I081-B, 108l B p 11 90 Geological Survey WILSON J M WILSON, J. M., 1958, Stratigraphic relations relations of non-marine 1958 Stratigraphic non marine Jurassic and strata of north central central and and northnorth pre-Them10polis of north pre Thermopolis Lower Cretaceous strata eastern Wyoming Wyoming in Strickland, J., ed., Powder eastern in Strickland J ed Powder River River Basin: Basin Casper, Casper Conference Wyoming Association 13th 13th Annual Annual Field Field Conference Wyoming Geological Geological Association Guidebook 77 78 Guidebook, p p. 77-78. WILTSCHKO, D. B. AND AND DORR, 1983, WILTSCHKO D B DORR J. J A., A 1983 Timing of deformation deformation in in Timing of Utah American American overthrust belt foreland of Idaho, Wyoming Wyoming and overthrust belt and and foreland of Idaho and Utah: Association Bulletin v. 67 1304 1322 Association of of Petroleum Petroleum Geologists 67, p. Geologists Bulletin, p 1304-1322. WINSLOW, N N. S. AND HELLER, Evaluation of WINSLOW S AND HELLER P. P L., L 1987, 1987 Evaluation of unconformities unconformities in in Upper Upper Jurassic Jurassic and and Lower Cretaceous nonmarine Lower Cretaceous nonmarine deposits, Bighorn deposits Bighorn Basin S A.: A Basin, Wyoming Wyoming and and Montana Montana, U U. S. Sedimentary Sedimentary Geology, Geology v. 53, p. 181-202. 53 202 p 181 1986 GeoGeo WORL, R R. G G., KOESTERER KOESTERER, M M. E E., AND HULSEBOSCH, T T. P., 1986, WORL AND HULSEBOSCH P the Bridger Wilderness and Sweetwater roadroad logic map map of of the Bridger Wilderness and the the Green Green-Sweetwater logic less area area, Sublette Sublette and and Fremont Counties, Wyoming: Reston, United less Fremont Counties United Wyotning Reston States Geological Survey Miscellaneous Miscellaneous Field States Field Studies Studies Map MF I636 Geological Survey Map (MF-1636v

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sedimentology and and diagenesis of the the Cadomin Cadomin sedimentology diagenesis of area, northwestern northwestern Alberta: Alberta Unpublished M S Unpublished M.S. Thesis, University University of of Calgary Calgary, Calgary, 173 p. Thesis Ca gary 173 p YOUNG, R R. G G., 1970 1970, Lower Cretaceous of Wyoming and YOUNG the southern southern Lower Cretaceous of Wyoming and the Rockies, in in Enyert Enyert, R R. L., Symposium Sandstones: Rockies L ed., ed on Wyoming Symposium on Wyoming Sandstones Casper, Wyoming Wyoming Geological 22nd Annual Fieldd ConferAssociation 22nd Annual Fie Confer Casper Geological Association ence Guidebook Guidebook, p p. 147-160. ence 147 160 Formation, Elmworth Formation Elmworth

area