Chapter 5Stratigraphic Cross Sections of the Eocene Green River Formation in the Piceance Basin, Northwestern Colorado

By Jesse G. Self, Ronald C. Johnson, Michael E. Brownfield, and Tracey J. Mercier

Chapter 5 of 7 Oil Shale and Nahcolite Resources of the Piceance Basin, Colorado By U.S. Geological Survey Oil Shale Assessment Team

U.S. Geological Survey Digital Data Series DDS–69–Y

U.S. Department of the InteriorU.S. Geological Survey

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U.S. Department of the InteriorKEN SALAZAR, Secretary

U.S. Geological SurveyMarcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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Suggested citation:Self, J.G., Johnson, R.C., Brownfield, M.E., and Mercier, T.J., 2010, Stratigraphic cross sections of the Eocene Green River Formation in the Piceance Basin, northwestern Colorado: U.S. Geological Survey Digital Data Series DDS–69–Y, chp. 5, 7 p.

ISBN: 1–4113–2668–2

iii

Contents

Introduction.....................................................................................................................................................1Stratigraphy of the Green River Formation, Colorado and Utah ............................................................1Cross Sections................................................................................................................................................1References Cited............................................................................................................................................6

Plates

1. Detailed cross section of line 1 ............................................................................................. link 2. Detailed cross section of line 2 ............................................................................................. link 3. Detailed cross section of line 3 ............................................................................................. link 4. Detailed cross section of line 4 ............................................................................................. link 5. Detailed cross section of line 5 ............................................................................................. link 6. Detailed cross section of line 6 ............................................................................................. link 7. Detailed cross section of line 7 ............................................................................................. link 8. Detailed cross section of line 8 ............................................................................................. link 9. Detailed cross section of line 9 ............................................................................................. link 10. Detailed cross section of line 10 ........................................................................................... link 11. Detailed cross section of line 11 ........................................................................................... link 12. Detailed cross section of line 12 ........................................................................................... link 13. Detailed cross section of line 13 ........................................................................................... link

Figures

1. Map showing location of the Piceance Basin, northwestern Colorado .............................2 2. Stratigraphic column for the oil shale zones of the Green River Formation .......................3 3. Stratigraphic column for the Piceance Basin, northwestern Colorado ..............................4 4. Map showing locations of the 13 cross sections in the Piceance Basin, Colorado .........5

Table

1. Names and definitions for the column headers for the spatial-data spreadsheet ...................................................................................................................................6

Introduction

For several decades, the U.S. Geological Survey (USGS) collected cores, cuttings, and other subsurface data from bore-holes drilled to evaluate the oil shale deposits in the Eocene Green River Formation in the Piceance Basin of northwestern Colorado (fig. 1). In Colorado, the Green River Formation was deposited in Lake Uinta during early to middle Eocene time, with the richest oil shale deposits in the Garden Gulch and Parachute Creek Members (fig. 2). It was from this area that data were collected and preserved for use by researchers and industry in anticipation of the time when Green River oil shale deposits would become an economically viable alternate source of unconventional fossil fuel.

The types of data collected include (1) thousands of Fischer (shale oil) assays (American Society for Testing and Materials, 1980) on cores and cuttings from rotary-drilled holes; (2) geophysical and lithologic logs of drill holes; and (3) measured sections from outcrops within the Piceance Basin. As part of the in-place assessment of the oil shale resources of the Green River Formation in the Piceance Basin conducted by the USGS, subsurface stratigraphic cross sections were created using various types of data for correla-tion. These cross sections are presented on plates 1–13 in this report.

Stratigraphy of the Green River Formation, Colorado and Utah

The Green River Formation consists of fine-grained lacustrine and fluvial-lacustrine rocks that were deposited in the Eocene Lake Uinta. The lake expanded early in its history, during the Long Point transgression (Johnson, 1985), to cover much of the Piceance and Uinta Basins, as well as the inter-vening Douglas Creek arch, an area between the two basins with low rates of subsidence. Lake Uinta remained a single unbroken lake across both basins and the Douglas Creek arch throughout most of its history, and most of the Green River Formation can be recognized in both basins. In the Piceance Basin (fig. 3), the early stages of the lake are marked by clay-rich oil shale zones referred to as the Garden Gulch Member,

whereas the younger oil shale zones deposited in the lake are carbonate-rich and referred to as the Parachute Creek Member. These oil shale units grade marginward into marginal lacus-trine rocks of the Douglas Creek and Anvil Points Members. The oldest member of the Green River Formation is the Cow Ridge Member, which intertongues with the variegated mud-stones, sandstones, and siltstones of the underlying Wasatch Formation. The names Garden Gulch, Parachute Creek, and Douglas Creek Members of the Green River Formation were first used by Bradley (1931); the name Anvil Points Member was first used by Donnell (1953); and the name Cow Ridge Member was first used by Johnson (1984). The sandstones and siltstones containing abundant volcanic debris that intertongue with the upper part of the Green River Formation are referred to as the Uinta Formation (Cashion and Donnell, 1974; see plate 13).

Cross SectionsThe 13 cross sections prepared for this assessment used

the same stratigraphic contacts as were drawn in previous studies (Pitman and Johnson, 1978; Pitman, 1979; Pitman and others, 1989) in order for resource-assessment results to be comparable. In these new sections, we also: (1) separate the Green River oil shale-bearing strata into alternating lay-ers of oil-rich zones (R-zones) and oil-lean zones (L-zones), following Cashion and Donnell (1972), because they are recognizable in much of the Piceance Basin; and (2) distin-guish between the clay-rich zones (zones R-0 through L-1) within the Garden Gulch Member, and the carbonate-rich zones (zones above L-1) within the Parachute Creek Member (fig. 2).

The cross sections (see fig. 4 for locations) were con-structed using 68 of the 780 oil-yield histograms created for this assessment, geophysical logs collected from wells drilled for oil and gas exploration, and 12 surface sections measured from outcrops within the Piceance Basin; table 1 provides information for the data used. The correlation datum for cross sections 1–12 (pls. 1–12) is the top of the R-4 zone, and for cross section 13 (pl. 13) the datum is the bottom of the R-5 zone. A horizontal scale of 1 in. = 0.5 mi and a vertical scale of 1.3 in. = 100 ft were selected to best accommodate the

Stratigraphic Cross Sections of the Eocene Green River Formation in the Piceance Basin, Northwestern Colorado

By Jesse G. Self, Ronald C. Johnson, Michael E. Brownfield, and Tracey J. Mercier

2 Stratigraphic Cross Sections of the Eocene Green River Formation in the Piceance Basin, Northwestern Colorado

City, town

Extrusive and intrusive igneous rocks

Mesaverde Fm. and Mesaverde Group coal-bearing rocks

Undivided Quaternary, Tertiary, Mesozoic, and Paleozoic

EXPLANATION

TERTIARY

CRETACEOUS

County line

Uinta Formation and undivided Tertiary

Green River Formation

Wasatch Formation and undivided lower Tertiary

0 50 MILES

Colorado

Index map

Delta

Eagle

Garfield

Gunnison

Mesa

Moffat

Pitkin

Rio Blanco

Routt

40

40

70

70

50

50

Grand Junction

GunnisonMontrose

Craig

GlenwoodSprings

39°00'

41°00'

40°00'

109°00' 108°00' 107°00'

Color

ado River

Yampa River Gre

en R

iver

Meeker

Rangely

SteamboatSprings

64

13

13

139

Montrose

RiflePiceance

Basin

Figure 1. Geologic map of northwestern Colorado showing generalized outcrops of the Cretaceous Mesaverde Formation (Group) and the Eocene Wasatch, Green River, and Uinta Formations in the Piceance Basin. Modified after Brownfield and others (2000).

Cross Sections 3

Figure 2. Stratigraphic nomenclature and correlation chart for oil-shale zones for the north-central part of the Piceance Basin, Colorado. This assessment uses the nomenclature of Donnell and Blair (1970) and Cashion and Donnell (1972) shown in yellow.

Donnell and Blair,(1970); Cashion and

Donnell (1972)

A-groove A-groove

B-groove B-grooveRich oil shale

zone R-6

Rich oil shalezone R-5

Rich oil shalezone R-4

Rich oil shalezone R-3

Rich oil shalezone R-2

Mahoganyzone

Correlation chart of stratigraphicnomenclature for oil shale zones

Para

chut

e Cr

eek

Mem

ber (

part)

Gree

n Ri

ver F

orm

atio

n (p

art)

Rich oil shalezone R-1

Rich oil shalezone R-0

Lean oil shale zone L-2

Lean oil shale zone L-1

Lean oil shale zone L-0

Lean oil shalezone L-4

Lean oil shale zone L-3

Lean oil shalezone L-5

Uini

ta F

orm

atio

n(p

art)

Was

atch

Form

atio

n(p

art)

Eoce

neUnitAge

Gree

n Ri

ver F

orm

atio

n

Gard

en G

ulch

Mem

ber

Para

chut

e Cr

eek

Mem

ber

Dyni (1974)

Gard

en G

ulch

Mem

ber

LowerMiddleUpper

Zone 9

Zone 10

Zone 11

Zone 12

Zone 13

Zone 8

Zone 2

Zone 3

Zone 4

Zone 5Zone 6

Zone 1

Zone 7

Mahogany zone

4

Stratigraphic Cross Sections of the Eocene Green River Form

ation in the Piceance Basin, N

orthwestern Colorado

Long Pointbed

North

Mahogany zone

Uinta Formation

GreenRiver

Formation

Top of Cretaceous

R-0, L-0 zones

R-1 zoneL-1 zone

R-2, L-2, R-3, L-3 zones

R-4, L-4, R-5 zonesL-5 zone

R-6 zone and B-Groove

Wasatch Formation

Wasatch Formation

Wasatch Formation

Cow Ridge Member,Green River Formation

Garden Gulch Member

Fort UnionFormation

Top of Mahoganyoil shale zone

South

Uinta Formation

ParachuteCreek Member

Parachute

Creek Mbr.

Freshwater lacustrine and paludal rocks with molluscs and thin coal beds

Lean dolomitic oil shale

Rich dolomitic oil shale with nahcolite and halite

Variegated mudstone, sandstone, and siltstone

Lean illitic oil shale

Rich illitic oil shale

Carbonate-rich marginal lacustrine mudstone with ostracodal, oolitic, and stromatolitic limestones

Volcanoclastic rocks

Disseminated nahcolite in oil shale

Nahcolite and halite

EXPLANATION

DouglasCreek Member

0 20,000 60,000 FEET

10 KILOMETERS0

500

1,000

1,500

400

200

FEET METERS

Vertical exaggeration x 40

Anvil Points MemberDATUM

Figure 3. Stratigraphic column for the Piceance Basin, northwestern Colorado, showing the Wasatch, Fort Union, Green River, and Uinta Formations and associated members.

Cross Sections 5

108°00’108°30'

12 MILES

40°00’

39°30'

Area underlain by the Mahogany bed

EXPLANATION

0

Colorado

R. 100 W.

R. 100 W.

R. 101 W.

R. 101 W.

R. 99 W.

R. 99 W.

R. 98 W.

R. 98 W.

R. 97 W.

R. 97 W.

R. 96 W.

R. 96 W.

R. 102 W.

R. 102 W.

R. 95 W.

R. 95 W.

R. 94 W.

R. 94 W. R. 93 W.

T. 8 S.

T. 7 S.

T. 6 S.

T. 5 S.

T. 4 S.

T. 3 S.

T. 2 S.

T. 1 S.

T. 1 N.

T. 2 N.

1

23

45

6

7

8

9

1012

11

13

Figure 4. Map showing locations of the 13 stratigraphic cross sections in the Piceance Basin, Colorado.

6 Stratigraphic Cross Sections of the Eocene Green River Formation in the Piceance Basin, Northwestern Colorado

distances covered and the need for stratigraphic detail. Sources of stratigraphic data include Johnson (1975) for the Long Point measured section, and Johnson and others (1988) for the Douglas Pass, Little Burma Road, and Tommy’s Draw sec-tions. Measured sections at Yellow Creek, Spring Creek, and

References Cited

American Society for Testing and Materials, 1980, Standard method of test for oil from oil shale: Annual Book of ASTM Standards, Part 25, Designation D 3904-80, p. 513–515.

Bradley, W.H., 1931, Origin and microfossils of the oil shale of the Green River Formation of Colorado and Utah: U.S. Geological Survey Professional Paper 168, 58 p.

Brownfield, M.E., Hettinger, R.D., and Johnson, E.A., 2000, A summary of the stratigraphy, coal resources, and coal-bed methane potential of Northwest Colorado: U.S. Geological Survey Professional Paper 1625-B, p. I1–I25,

Cashion, W.B., and Donnell, J.R., 1972, Chart showing correlation of selected key units in the organic-rich sequence of the Green River Formation, Piceance Creek Basin, Colorado, and Uinta Basin, Utah: U.S. Geological Survey Oil and Gas Investigations Chart OC-65.

Cashion, W.B., and Donnell, J.R., 1974, Revision of nomen-clature of the upper part of the Green River Formation, Piceance Creek Basin, Colorado, and Eastern Uinta Basin, Utah: U.S. Geological Survey Bulletin 1394-G, 9 p.

Table 1. Names and definitions for the column headers for the spatial-data spreadsheet (Spatial_Information.xlsx).

Column name Column definition

USGSID Unique ID assigned by staff geologistCOMPANY Name of the company or agency that drilled the borehole NAME Name of the borehole assigned by the company or agency that drilled itSECTION SectionTOWNSHIP Township RANGE RangeLATITUDE Latitude, in decimal degrees, North American Datum 1927, software-calculated, original recordLONGITUDE Longitude, in decimal degrees, North American Datum 1927, software-calculated, original recordCOUNTY Name of county in Colorado DEPTH IN FEET Total depth of the borehole, in ftPLATE NUMBER The Piceance Basin cross section where that piece of data can be found

Donnell, J.R., 1953, Columnar section of rocks exposed in Field

Conference in northwestern Colorado, Rocky Mountain Association of Geologists Guidebook, Field Conference, Northwestern Colorado, p. 14.

Donnell, J.R., and Blair, R.W., 1970, Resource appraisal of three rich oil-shale zones in the Green River Formation, Piceance Creek Basin, Colorado: Colorado School of Mines Quarterly, v. 65, p. 73–87.

Dyni, J.R., 1974, Stratigraphy and nahcolite resources of the saline facies of the Green River Formation in northwest Colorado; in Murray, D. Keith, ed., Guidebook to the Energy Resources of the Piceance Creek Basin, Colorado, Rocky Mountain Association of Geologists, 25th Field Conference, p. 111–122.

Johnson, R.C., 1975, Preliminary geologic map, oil-shale yield histograms and stratigraphic sections, Long Point quad-rangle, Garfield County, Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF-688, scale 1:24,000 (Two sheets with descriptive text).

Johnson, R.C., 1984, New names for units in the lower part of the Green River Formation, Piceance Creek Basin, Colorado: U.S. Geological Survey Bulletin 1529-I, 20 p.

Johnson, R.C., 1985, Early Cenozoic history of the Uinta and Piceance Creek Basins, Utah and Colorado, with special reference to the development of Eocene Lake Uinta United States: Rocky Mountain Section, Society of Economic Paleontology and Mineralogy: Denver, Colo., p. 247–276.

References Cited 7

Johnson, R.C., Nichols, D.J., and Hanley, J.H., 1988, Stratigraphic sections of lower Tertiary strata and charts showing palynomorph and mollusc assemblages, Douglas Creek arch area Colorado and Utah: U.S. Geological Survey Miscellaneous Field Investigations Map MF-1997, 2 sheets.

Pitman, J.K., 1979, Isopach, structure contour, and resource maps of the R-6 oil-shale zone, Green River Formation, Piceance Creek Basin, Colorado: U.S. Geological Survey Miscellaneous Field Investigations Map MF-1069, scale 1:126,720.

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Pitman, J.K., and Johnson, R.C., 1978, Isopach, structure contour, and resource maps of the Mahogany oil-shale zone, Green River Formation, Piceance Creek Basin, Colorado: U.S. Geological Survey Miscellaneous Field Investigations Map MF-958, scale 1:126,720.

Pitman, J.K., Wahl Pierce, Frances, and Grundy, W.D., 1989, Thickness, oil-yield, and kriged resource estimates for the Eocene Green River Formation, Piceance Creek Basin, Colorado: U.S. Geological Survey Oil and Gas Investiga-tions Chart OC-132.