Oil Shale, Part II: Geology and Mineralogy of the Oil Shales of the Green River Formation, Colorado, Utah and Wyoming

Article

Oil shale, part II: geology and mineralogy of the oil shales of the Green River formation, Colorado, Utah and Wyoming

JAFFE, Felice

Reference

JAFFE, Felice. Oil shale, part II: geology and mineralogy of the oil shales of the Green River formation, Colorado, Utah and Wyoming. Colorado School of Mines Mineral Industries Bulletin, 1962, vol. 5, no. 3, p. 1-16

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The Colorado School of Mines Mineral Industries Bulletin is published every other month by the Colorado School of Mines Research Foundation to inform those interested in the mineral industry regarding the elements of the geology and mineral resources, mining operations, metal markets, production statistics, economics, and other aspects of the mineral industry. This publication may be obtained for a yearly subscription charge af $1.00 for the six issues published from July through May of the following year. Past issues still in print may be had for 25c each. Address your order to the Department of Publica- tions, Colorado School af Mines, Golden, Colorado. Entered as second class matter at the Post Office at Golden, Colorado, under Act of Congress, July 16, 1894. Copyright 1962 by The Colorado School of Mines. All rights reserved. This publication or any part of it may not be reproduced in any form without written permission of the Colorado School af Mines. Volume 5 May, -1962 Number 3 OIL SHALE Part II GEOLOGY AND MINERALOGY OF THE OIL SHALES OF THE GREEN RIVER FORMATION, COLORADO, UTAH AND WYOMING By Felix C. Jaffe'

Colorado School of Mines Research Foundation, Inc. Colden, Colorado

INTRODUCTION been, up to now, a major deterrent for the establishment of a healthy domestic oil-shale industry. To a certain extent, oil In a previous Mineral i11d11stties Bulletin on oil shale shales also suffer from the conservative approach which has (Volume 5, Number 2) the nature of different oil shales and been prevailing in the mining industry in recent years and, related, oil-yielding, sedimentary roc:ks was described. Known indeed, a certain amount of courage is required to enter into oil-shale rese1·ves of the major districts were indicated, and a completely new field, in which many technical, pxoduction, oil-shale CAl>loitation in several countries of the Eree world and and marketing problems am as yet unsolved. Howeve1·, exploita- the communist bloc was briefly reviewed. In this study, of tion of oil shale is becoming increasingly competitive, as general nature, the conclusion was reached that oil shales are domestic peb·oleum reserves are being rapidly depleted and a raw material of signilicant and rapidly increasing importance, exploration and production costs are constantly rising. and that they can be mined, retorted, and refined under favorable economic conditions. Quantitative predictions of future production of oil from oil shales liave been disproved to such an extent that it does In the United States, past exploitation efforts have been not seem advisable to repeat similar errors in this study. The only of a sporadic and limited nature, and at present no in- fact remains that truly enormous reserves of oil shale are in dustrial activity can be reported in this field . However, this existence, and that the inception of their commercial exploita- country occupies a privileged position for future production tion is only a matter of time. In Colorado, in particular, oil of oil from oil shale, since the largest known .reserves of the shale is definitely a major resource of the future. world are concentrated in the western part of its territory, The purpose of this Bulletin is to gather in one single principally in the Green River formation. Over 16,000 square publication the essential information published on the Green miles are underlain by oil shale.~ in the states of Colorado, Utah River oil shales since the classical investigations of Bradley, and Wyoming. The Piceance Creek D<1sin, Colorado, is without some thirty years ago. doubt the largest single l·nown oil-shale deposit of the world. Pertinent data on other oil-shale districts will be men- The availability of sufficient quantities of oil products, at tioned, where a better understanding of the western oil-shale competitive prices, from conventional petroleum sources has field can be obtained thereby.

,I I. THE GREEN RIVER FORMATION Piceance Basin is, reservewise, the largest known oil shale deposit of the world (Jaffe', 1962). General description Each lake has its own particular sedimentation features. The Green River form::ition is composed of a sequence of For instance, trona, a naturnl sodium sesquicarbonate (Na~CO~ · predominately lacustrlne sediments, with inteifi11gering of NHC0,1• 2H~O) is found in commercial quantities onJy in the fluviatile sediments. It extends over approximately 16,400 Wyoming trona district which lies in western Sweetwater square miles, and is some 1,500 to 2,000 feet thick. Several County. In this area, beds of solid trona are known to extend thin analcitized tuff layers are intercalated in this sequence. over 1,000 square miles, but onJy a part of the area, approxi- The formation lies confonnably over the Tertiary Wasatch mately 100 square miles, is of potential commercial value formation, which is composed principally of fluviatiJe secli- (Mannion and Jefferson, 1962). According to Fahey (1962), ments, and, in turn, is overlain conformably by younger forma- the b·ona of the Green River formation will probably be a tiol')s, i:n which a fluviatile type of deposition is again pre- sow·ce of soda ash for hundreds of years1 • Each square mile of dom.i1iant. It is of interest to note that oil shnles of the other b·ona bed contains more than 16 million tons of trona, from major districts of the world were generally deposited in a whicl1 it is estimated that about nine million tons of soda ash marine environment. can be produced, after deducting for impurities in the trona Three different lakes were in existence at apl.)l'Oximately bed, and the incomplete recovery by room-and-pilJar mining. the same time in the lacustrine phase of the Green River Current production is estimated at 900,000 tons of soda ash formation: Lake Uinta, the largest one, lying south of the per year, which corresponds to approximately 15 percent of Uinta Mountains, Gosiute Lake, in Wyoming, and a third, as the total domestic nntmal and synthetic soda ash production. yet unnamed lake, tl1at occupied a relatively small basin in Recent mineralogical studies have confirmed subtle differ- the exb·eme west of Wyoming, now refened to as the Fossil ences of sedimentation and environment in the different basins Syncline (fig. 1). Lake Uinta. was subdivided into two basins: of the Green River formation (Milton and others, 1960). the large Uinta Basin in Utah, and the relatively small Piceance Creek Basin in Colorado. These two basins were The topography of the region occupied by the Green connected by a narrow isthmus, which was in existence at least River formation, in Colorado and Utah in particular, is char- at the time of the Parachute Creek member deposition (Bradley, acterized by high steep-sided plateaus, with steep outward- 1948). fncing escarpments several thousand feet high. Precipitous cliffs are common. The streams which flow over the rocks of During Eocene times, the Uinta-Piceance Basin was a the Green R.iver formation have cut nanow, steep-sided valleys subsiding basin filled with sediments derived from actively or deep canyons with abrupt walls. Vegetation other than rising positive areas suuounding it, notably the Uinta Moun- ground cover is frequently scant, except for tl1e canyon bottoms. tains. It bas been considered as a b·ue zeugogeosyncline (Jones, However, spruce and aspen forests are in existence on many 1957). mesas. Two areas in the Green River formation have been de- Swface occupied by the Green River formation: scribed in detail recently. The Cathedral Bluff area is situated State and County Square miles in the western part of the Piceance Creek Basin, and occupies Colorado an area of approximately 385 square miles. (Donnell and Garfield, Mesa and Rio Blanco...... 2,592 others, 1953). The Bonanza-Dragon area is located in the Utah Uinta Basin, on the Colorado-Utah boundary (Uintah County, Uintah, Duchesne, Carbon and Wasatch 4,680 Wyoming Utah, and Rio Blanco County, Colorado) . It occupies an area Uinta, Sweetwater and Lincoln...... 9,192 of approximately 500 square miles. Many veins in this area are filled with gilsonite, which is a particular variety of Total ...... 16,464 asphaltite. In fact, most of the gilsonite veins of the Uinta Source of data: Belser, 1949. Basin are within the Bonanza-Dragon area (Barb and Ball, In comparison, the Estonian oil-shale field, which has been 1944; Hunt and others, 1954; Cashion and Brown, 1956; in exploitation since 1918, only occuoies an area of approxi- Pruitt, 1961). Gilsonite is mined underground by hydraulic jet mately 1,400 square miles (von Winkler, 1930; Luts, 1938). cutting and the slurry is transp01ted by a 72-mile long pipe line The Lothian oil-shale field, Scotland, is still much smaller. It to the refining plant near Grand Junction, Colorado (Lenhardt, covers an area of approximately 100 square miles ( Greensroith, 1958; Baker, 1959). 1957). Oil-shale mines have been in ex.istence in Scotlru1d for over a century. The three Green River formation lakes are characterized by similar pattems of evolution. A first transgressional phase Stratigraphy was followed by a long pedocl 0£ stability with minor fluctua- No unifolm stratigraphy can be ex-pected from a sedi- tions. The oil shales were deposited primarly during this period. mentary formation occupying over 16,000 square miles. such Finally, gradual regression took place. In this dessication phase, as the Green RNer formation. Thus, it becomes impossible to saline conditions were prevailing, leading to deposition of describe the whole formation by means of one single strati- sodium salts such as b·ona and nahcolite. graphic section. The three lakes are stratigraphically contemporaneous, Considerable info1mation is available on the strati~raphy and oil shale forming material was deposited in each of them of the Green River formation in Colorado and Utah (Abbott, in various amounts. The largest nc:::cumulaliou of organic ma- 1957; Donnell, 1961) . As for Wyoming, no encompassing study terial took place in. the comparatively small Piceance Creek has yet been published, but interesting data may be obtained Basin, Colorado. Hence, the largest oil-shale J:eserves of the in several recent publications. (Bradl ey, 1959 and 1961; Green R.iver fo1matio11 occur in this state, and geological and Cubertson, 1961; Masmsky, i:n press; Masursky and Pipiringos, shale.~ economic studies of Colorado oil are indeed of para- 'Soda ash is the term used in industry for sodium carbonate mount importance. At the present state of knowledge, the (Na,CO,).

Page 2 Colorado School of Mines I IDAHO -~

,.....__ -- --FOSSIL ~ SYNCr, • Rawlings I

@Salt Lake SANO WASH City UTAH BASIN Craig ~ • 0 25 50 Miles COLORADO

LEGEND

~ Oil shale unappraised ~ or low grade ....lll./ ~ ~Rifle---- Glen.woodSprings BATTLEMENT

Oil shale more than 15 feet thick, Grand MESA and yielding 25 gallons of oil per ton of shale, or more. Junc~ion~'l/ GRAND - ~ '// MESA

Figure 1. Index map of the Green River formation in Colorado, Utah and Wyoming. (After D. C. Duncan, 1958)

Mineral Industries Bulletin Page 3 1959; Oriel, 1961; Pipiringos, 1955 and 1961). The rich zone, a term initially introduced by Dr. Tell In this study, two typical stratigraphic sections of the Ertl, aud frequently employed by mining engineers, is an Piceance Creek Basin and the Uinta Basin are indicated in arbitrary portion of the Mahogany zone that seems most suit- Figures 2 and 3. They were measured in parts of the Green able for underground mining. It is composed of high-grade oil River formation in which oil shales have long since been con- shale, and parUng at the top nncl bottom is expected to yield 1 sidered to be of particular economic significance • In a detailed satisfactory roof and floor stones. stratigraphic section, lithology is generally complemented by Several thin analcitized tu££ beds are intercalated through the estimated oil yield (gallons per ton) , the resistivity (ohms the sediments of the Parachute Crnek member. Some of them m 2/m), and the spontaneous potential (millivolts). can be observ.ed over large areas and are used as key beds for Only the oil-shale bearing members of the Green River stratigraphic l'eference and structural mapping. One of them, formation will be further described. commonly referred to as Mahogany marker, is in existence 3 to feet above the top of the Mal1ogany bed. has been Parachute Creek Member 14 It traced throughout most of the Piceance Basin, and can be The richest and thickest oil shale beds are contained in correlated with a similar bed in the Uinta Basin. Most of the the Parachute Creek member. Therefore, this member was sub- tuff beds arn porous, and some contain a tarry, black oil divided further into a lower and upper zone (Bradley, 1931), resembling humic acids (A. Houghton, in Ertl, 1955, p. 99) . or into a lower, middle and upper zone (Duncan and Denson, At 280 to 345 feet above the Mahogany marker occurs the 1949; Donnell, 1961). The richest oil shales occur in the upper lowermost and most persistent of a series of marlstone beds zone, in which sedimentation conditions were more stable in which numerous crystal cavities were formed by the solu- (fig. 4). tion of crystals of gypsum and anhydrite. Special designations have been applied to certain oil-shale units of the upper zone. They have either an economic conno- Depositional facies tation or are used as markers in surface mapping and drill An interesting study of facies distribution was carried out sections. in Uinta Basin by Picard (1955). Although it may not apply The basal part of the upper zone, from which the highest sb·ictly to the other basins of the Green River formation, it can oil yields are obtained, is called Mahogany ledge at the outcrop be considered as typical and, thus, will be discu.ssed briefly. and Mahogany zone in the subsurface. The name Mahogany Five distinct depositional facies have been described in is derived from the fact that some of the richest beds weather the Uinta Basin. to look like antique unfinished mahogany. In polished surfaces, At the bottom of the formation, Picard noted a black this type of shale simuJates old mahogany in a remarkable shale formation, up to 1,800 feet thick, corresponding to sedi- manner (Bradley, 1931, p. 23). mentation in a deep, thermally stratified, cold-water lalce, probably fanned by coalescence of small lakes and marshes on the The thickness of the Mahogany zone and its oil content flood plains of the rivers and sb·eams flowing into the area. are subject to considerable variations. In the central parts of Small lenses and isolated salt crystals indicate that at times the basin a thickness of 110 feet was driUed, of which 60 feet deposition occuffed in brackish waters. The black shale fades in continuous sequence showed an average oil content of 41.2 is followed by a delta facies, composed primarily of green, gallons per ton. In the U. S. Bureau of Mines experimental grayish green and gray shales and sandstone. mine near Rifle, Colorado, a 73-foot section, for which mining The base of the delta facies is a gradatiomtl with the operations were planned, contains an average of about 28 underlying black shale facies, and the usual procedure is to gallons per ton. A decrease in thickness and oil yield has been place the contact on a regional basis at a distinctive electric noted toward the margins of the basin, and in the extreme log break (Picard, 1957). A thickness of 800 to 2,000 feet northwestern area it cannot be distinguished from the adjacent has been observed in the subsurface. The overall depositional beds. character of this facies is shallow lacustrine to deltaic. Within the Mahogany ledge, or zone, the Mahogany bed is a persistent thin unit of extremely rich oil shale, yielding After the delta facies deposition, the Parachute Creek and from 50 to 80 gallons of oil per ton. The thickness of this bed Evacuation Creek members were deposited, in what could be varies from 3 feet along the margin of the basig to 10 feet designated as an oil shale facies, during which Lake Uinta in the deeper parts ( 5 to 15 feet in the Naval Oil-Shale was at its maximum extent and essentially stable. Reserve No. 2, Uinta Basin, Utah). This ledge is bounded at Several beds of water-laid tuffs are intercalated in the oil the top and bottom by lean oil shales, which weather more shale facies. Theil' origin is uncertain, si11ce no volcanic center readily than the richer oil shales and, frequently, form charac- is 'J.."Uown in the Green River formation during Eocene times. teristic grooves known as A-groove and B-groove, respectively. An eastern location has been postulated for their point of These grooves are convenient reference beds in drill cuttings origin, as they tl1in out progressively towards the west. The and appear on electric resistivity logs as characteristic points possibility of other ash falls taking place in the lower members of low resistivity, in contrast with the high resistivity of the of the Green River formation cannot be ruled out completely. Mahogany zone. The uppermost and most distinctive resistivity However, pre.vailing conditions in the fluviatile facies were less dip corresponds to the lean oil shales of the A-groove, which stable, and it is probable that tuffs deposited in this environ- is generally about 10 feet thick, whereas the resistivity dip ment were reworked and destroyed rapidly (Donnell, 1962). corresponding to the lean oil shales of the B-groove is more The question may arise whetl1er the association of oil

Page 4 Colorado School of Mines Formation Member Topographic Lithology Depositional Thickness and age expression environment (in feet)

Evacuation Creek Buff to light brown Barren marlstone, shale, silt- Fluviatile - 1,250 rounded cap of the stone and sandstone lacustrine rim and hilly topography on the pla- ,• teau

Parachute Creek Precipitous whitish Oil-yielding marlstone and Lacustrine 500 - l, 700 cliffs near the crest shale, tuff beds of the plateau rim

Anvil Points Benches and cliffs 303 gray shale, 253 gray shale Lacustrine Green River 1,530 - 1,870 (Eastern part) and interbedded, thinbedded brown (near-shore facies) (Eocene) Lateral equiva- and gray sandstone, 203 massive lent to Douglas brown and gray sandstone, 103 Creek and Garden light brown barren marlstone; silt- Gulch Creek stone, algal and oolithic limestone

Garden Gulch Gray, steep slopes Papery, flaky shale, marlstone, Lacustrine 100 - 1,000 locally thin beds of sandstone, oil-shale breccia, and ostracodal, oolithic and algal limestone

Douglas Creek Brown and buff Crossbedded and ripple-marked Lacustrine 20 - 800 benches sandstone, algal and ostracodal (near-.shore facies) limestone, and oolithic sandstone and limestone

Wasatch Ohio Creek Lowland Brightly colored clay and shale, Dominantly fluviatile 375 - 3,500 (Eocene) conglomerate lenticular sandstone, conglomerates, pebbly sandstone, limestone, coal, carbonaceous shale

Unnamed unit Ledge-forming Brown feldspathic sandstone, gray Non-marine 0 - 500 (Paleocene) and brown clay and shale, thin coal Scattered short-Ii ve beds swamps

Pebbles and cobbles of red and Continental to 5 (Paleocene) black chert and quartzite up to 4 tb 5 in. in diameter in sand- . stone matrix

Mesaverde Prominent benches, Fine to coarse-grained sandstone Fresh water, brackish 5,000 (Upper ridges and cliffs with interbedded shale and sandy and marine at or near Cretaceous) shale; several coal beds to ancient strand lines

Figure 2. Stratigraphic sequence in the Piceance Creek Basin, Colorado. (After J. R. Donnell, 1961)

Mineral Industries Bulletin Page 5 Formation Member Topographic Lithology Depositional Thickness and age expression environment (in feet)

Uintah Brown and red cliffs Brown and red sandstone and Fluviatile (Eocene) (Only basal part) siltstone

Evacuation Creek Brown resistant ledge Horse Bench sandstone bed Fluviatile 540 (Only base is represented)

Parachute Creek Steep slopes and Gray and brown marlstone and Generally lacustrine, 380 - 500 Green River cliffs siltstone, and brown sandstone, with interfingering (Eocene) oil shale, tuff beds fluviatile sediments

(Basal part) Mahogany oil shale bed (5 - 15)

Douglas Creek Rugged cliffs and Brown, gray and red sandstone Predominantly 2,500 stiff slopes and siltstone, green and gray fluviatile shale, brown and gray oolithic limestone beds

Figure 3. Stratigraphic sequence in the Naval Oil-Shale Reserve No. 2, Utah. (After W. B. Cashion, 1959) has an average thickness of 32 feet (Conant and Swanson, facies was deposited in a lacustrine environment. To the north, 1961). east and south, these predominantly lacustrine sediments grade Likewise, volcanic materials are wjdespread in the Scot- into dominantJy fluvjal sediments of the lower part of the tish oil-shale group (Kennedy, 1943; Greensmith, 1961). Uinta Basin. In fact, oil-shale facies and saline facies coincide to a great e:dent, and nuhcolite occurs as concretions up to Reverting to the case of the Parachute Creek member, it five feet in diameter and as layers up to four inches thick in can be conceived that the partial decay of tuffaceous material the l\fahogan}' ledge in the Picearice Basin (Ertl, 1947; Glass, in a lacustrine basin liberated the elements necessary for the 1947). exttaord·inary development of plankton, which ·was later con- Finally, a calcareous and sandy facies can be noted, cor- verted into kerogen. It is indicated to verify such a hypothesis, responding to the filling up of the different Green River lakes. and to investigate whi,ch chemical elements, if any, derived from tuffs, :u·e responsible fol' this vegetation bloom. Hence the Paleontology importance of detaiJed study of trace element~. A great variety of fossils has been found and determined Another type of volcanic activity is known from the Battle- in the Green River formation. ment Mesa and the Grand Mesa, the two southern outliers of Several thousand specimens of small reptiles, mammals the Piceaoce Creek Basin. In this region, thick volcanic flows and shore birds were discovered in a sandy cleltaic facics along of basaltic composition extruded from the locn.l fractures. These the basin of Raven Ridge, in the eastern part of the Uinta volcanic flows are younger than the oil shales (Donnell, 1962). Basin (Kay, 1957; Ga?.in, 1959). An OCClU'rence of mammalian Only a small remnant of a basaltic flow of similar nature is remains has been reported at a locality near Tabernacle Butte, present in the Piceance Creek Basin itself (Donnell, 1961). Wyoming (McGrew and .Berman, 1955). A saline facies can be noted in the upper part of the Species belonging to the following orders were identified Green River formation. It is characterized principally by me- in Utah: dium brnwn, calcareous, soft to hard and brillle, thinly bedded Crocodiha (crocodiles) shales with intercalation of sandstone ~eds and oil-shale beds. Chelonia (turtles) Nahcolite crystals (Na:S:C03) are frequent in these rocks Squamata (lizards and snakes) (Picard, 1955). The saline facies marks the beginning of the Carinata (birds) retreat of Lake Uinta and the incipient end of. lacustrine en- Marsupialia (marsupials) vironment. In the central part of the Uinta Basin, the saline Insectivora (mole-like animals)

Page 6 Colorado School of Mines :i 0... c l/l -+..... Cl) l/l OJ c Cl) :::!". :i

Figure 4. Typical cliff in the Piceance Creek basin, Colorado. (Exposure on the East Fork of Parachute Creek.) The bedded sediments dsilJTe in the vertical part of the cliff in the foreground belong to the upper oil-shale zone (Upper Parachute Creek Member). The Mal10aany ledge is clearly visiMe in the foreground (lower right of the photograph). It is situated between two well marked grooves, the A-groove, at its top, and the B-groove, at its bottom. The A-groove can also be seen as a narrow white DJ line on the cliffs ·in the center of the figure. O'Q" Cl) Approximate thickness: Upper oil-shale zone (from B-groove to cliff top): 500 feet; Mahogany ledge: 100 feet. -....J Photography by courtesy of D. C. Duncan, U. S. Geological Survey. In the Fossil Basin (western Wyoming), hundreds of Structure thousands of beautifolJy preserved fish are entombed in the The Uinta-Pfoeance structw-al trough is surrounded by varved sediments. Twenty different species have been deter- positive elements. It is bounded on the west by the vVasatch mined, of which the most frequent are Diplomystus densatus Plateau, on the nortb by the Uinta Mountains, and on the east Cope and P7iareodus encaustis Cope (Veatch, 1907). Fossil by the Elk Mountains and the White River uplift. Its southern fish quarries of this basin have supplied museums over the boundnries are less well-defined, being essentially controlled world (Bradley 1936 and 1948; Tracey and Oriel, 1959). It is by the Wasatch Plateau (Book Cliffs), the San Rafael swell, interesting to note that in nonvarved sediments only a dis- the La Sal Mountains and the Uncompahgre Plateau (Jones, ordered mass of broken and chewed-up fish bones are pre- 1957). The majo1· positive elements surrounding the Green served. Un,usual accumulation of fishes in sediments may be River formation in Wyoming are the Wyoming Range in the due to mass mortality. Phenomena of this kind, their causes and west, the Wind River Mountains and the Sweet.water uplift significance to paleontology have been reviewed recently in the north, the Rawlins uplift and the Sierra Madre Moun- (Brongersma-Sanders, 1957). tains in the east, and the Uinta Mountains in the south. The In some instances, osb·ac0des can be valuable stratigrapltic Rock Springs uplift separates the Washakie Basin in the east guides (Swain, 1956). Mollusks from cenb·al Utah were de- from the Bridger Basin in the west. scribed by La Roque ( 1956). Green River deposition was followed in the Eocene by a period of elevation in the Uinta Mountains. It was at this time The most comprehensive study of microfossils associated that the Uinta Basin and the Piceance Basin were separated with oil shales was carried out by Bradley ( 1931) . An abundant by the Dougfas Creek Arch, which began to rejuvenate and flora and fauna was described nud reproduced in ten excellent to rise. The general struch.iral axis of thfa arch is north-south. plates. Later on, another period of differential uplift and collapse occurred, in which the Uinta Mountains reached their Flora present development. A good indication of this collapse, in Bacteria the Uinta Basin, is the set of tension cracks, some of which Fungi are now filled with gilsonite (Crowley, 1957). Algae (Flagellata and Cyanophyceae) The Creen lliver sediments are essentially horizontal or Bryophyta (mosses) gently inclined. However, dips up to 27 degrees were measured Pteridophyta (fern plants) locally, and small, very low folds are superimposed on the Spermatophyta (Gymnospermae and Angiospermae) major structural features. Folding bas occurred before and during the deposition of Fauna the Green. River formatfon, especialJy before the deposition Protozoa of the Parachute Creek member. Consequently, the structure Arthropoda (spiders, insects) of the surface rociks does not coincide with that 'Jn existence in the subsurface of the basal Green River and the underlying The abundance of fossils associated with oil shales clearly formations. indicates that a very intense biological activity was in existence Normal faults, with a small displacement in the order of in the various Creen lliver lakes, in which blue-green algae 50 feet are noted. Donnell ( 1961) mentions that in the apparently dominated the rich algal flora. Urndley ( 1931, Piceance Creek Dasin roost faults, like the folds, trend to the p. 41) has calculated, for instance, that in some oil shales about northwest. The fau lts are generally coated or filled with calcite, 5,700 individuals of one species, Chrocococcus, are contained and at one place the calcite includes many stringers of a solid in one cubic centimeter. The oil shale sample on which this hydrocarbon resembling gilsonite. calculation was based yields 44 gallons of oil per ton. A well-defo1ecl system of northwest-northeast-b·ending An almost perfect germling cell of S71irogyra, which still joints, 0£ some regional significance, can be recognized in the contai11s its spiral chloroplast, was described recently from the Pice:mce Creek Bnsin, and is also described in pmts of the Will-ins Peak Member of the Green River formation iti Wy- Uinta Basin. A partial adjustment of streams to this joint oming. The cell is turgid and the dark-colored chloroplast system has resulted in a b·ellislike drninage pattern in t11e west- appears to be suspended in a nearly colorless, transpare11t central part of the Piceance Basin and in the Naval Oil-Shale matrLx. The fact that this cell l1as retained its rounded turgid Reserve No. 2, Utah (Cashion, 1959, and Donnell, 1961). form drnfog the compaction of the enclosing oil shales implies tbat the cen was permeable enough so that virtually perfect II. OIL SHALE hydrostatic balance was maintained between the fluids within Physical description and outside the cell (Bradley, 1962 a). Colorado oil shale varies from light brown to black in The great pro.fusion of remains of large fly larvae in the color. Other oil shnles may be black (Scotland, Ontario, New oil shales seems to indicate a moderate depth of water. These South Wales), dark brown (New Brnnswick, Argentina, Bul- larvae are extremely abw1dant in the upper part of the upper garia), blacik brown with a satin lustre (Scotland), gray (Scot- oil-shale zone on Parachute Creek, where there are more than land), pale yellow (Brazil), pale bricik red, red brown, oliv 120 feet of larvae-bearing beds. green or dark red (Estonia) (Cunningham-Craigh, 1929; Tirat- The compound eyes of minule atlult insects are common ~uu , 1951). in some oil-shale beds. The soft lens part o.f the eyes was Oil shale is dense, tough and resistant. Because of its decomposed, leaving 01tly a netlike supporting tissue, which greater resistance to erosion lhau in Hccompanying rocks, over- presumably consisted of cuticular p1·otein (Bradley, 1948) . hangi11g ledges may be fo1med on the steep walls of the canyons Pollen and fungi spores were c:u:ried in by wind. Records existfog in the Green River formation.. Although o.il shale is are available of times when as many as 1,000 spores per square generally laminated, it often breaks across the bedding with centimeter fell (Durham, 1942). Pine and spruce llollen grains a conchoidal fracture. are common and distinctive. Thin-bedded deposits are remarkably flexible. The flexi-

Page 8 Colorado School of Mines Figure 5. Colorado oil shale (actual size).

:::l CL c Ill.,..... CD Ill OJ c .....CD :::l

Note the finely lami1lated texture. Microfaulting and necking, 1>isible in different parts of the sample, were probably originated during compaction.. Note al. o two small lenses composed of pyrite crystals (light in figure). The bottom of the sample is composed of tuft, showing an irregular tipper surface which existed prior -u Ill to the oil-shale deposition above it. The dark zones in the tuft are secondary conce11tratio11s of organic matter mi.grated into the tuff from the oil shale. cro. CD Sample by courtesy of Professor N. E. Grosvenor, Colorado School of Mines. bility of oil shales distinguishes it from ordinary carbonaceous these 50 minentls, eight are known to exist exclusively in the shales, which !ll'e brittle. Green, River formatio11. WitlJ fortlier research currently under The freshly broken sw-face of l'lch oil shale gives off a way, it can be anticipated that the Green River formation will hnracteristic petroleum odor and bums with a sooty smoke. rapidly become a classical region for the study of :mthigenic Evidence gathered in drilling and mining operations near the minerals and their mode of formation. oil-shale cliffs iJiclicates tlmt at one time climatic conditions In this study, only the principal minerals more closely were so favorable for spontaneous combustion that this oc- associated with oil shales will be described in detail, according curred at numerous locations. Burning in the interior of the to thefr modern classification (Carozzi, 1960). A complete list mountain occurred in places for a distance of a hundred feet of authigenic minerals determined so Far in the Grnen River and even more from the face of the cliffs. Hence, in these formation is given in Figure 6. locations the outcrop is now free of kerogen (Hartley and Composition and origin of kerogen, the organic constituent Brinegar, 1959, p. 46). of oil shales, will be discussed in a further bulletin. ln general, o'il shales nre regulai·ly bedded, and, with a few exceptions, thinly laminated (fig. 5). Rhythmic lamina- Average composition of 25-gallon-per-ton oil-shale sections of tion, by far tbe most frequent type, is due to a regular alteration the Mahogany zone in Colorado and Utah of microgranuJ.ar layers of carbonate and clay witb a layer of Weight Percentage structureless orgnnic material. In some high-grade \rarieties, Mineral constituents ···················-····· 86.2 lamination is not app1uent until after the rock has been heated Dolomite ...... 35 and the oil driven off (Winchester, 1918). Weathering often reveals the thin bedding and also produces papery shale in the Calcite ·····················-·---·················· 15 thinly laminated shales (Cashion, 1957). Feldspars ········-·-··························· 25 In the Green River fonnati,on, paper shales are essentially Quartz ...... 15 a product of atmospheric weatherlng actions, and grade into Clay ··············:···-·-····················---- 5 massive or, at least, well-cemented mcks away from the out- Pyrite ··········-··-······························· 1 crop. True paper-shale bands, called papiraceo, are found in Analcite and other minerals ·········- 4 fresh Paraiba oil sbales (Brazil). In this tyPe of shales, laminae of the thickness of paper can be peeled readily (Ertl, 1962). Kerogen ·················-···········--·--··········-·13.8 A weathered high-grade oil shale is generally blue-gray Total ····---·····································100.0 100 in color. In contrast, the colors of weathered lean oil shales range from light gray to brown. Resistance to weathering Source of data: U. S. Bureau of Mines, 1960. increases with oil content. Authigenic minerals Color changes during tbe weathering process are due to Dolomite and calcite are the predominant minerals in some chemical action, probab'ly oxidation of the organic m&tter Green River oil shale. The grains, which are essentially equi- in contact either with air or water. The penetration of this dimensional, average about 0.008 millimeters in diameter. kind of chemical action varies slightly with the amount of Perfect rhombs of dolomite and calcite are also fairly common kerogen in the rock. The greatest visible thickness of the and are generally of the same size as the equidimensional oxidized coating is never more than 18 inches and usually grains. Both carbonates must have been fo1med 'befoxe sobdili- about the thicl-ness of letter paper. A fresh fracture will change cation of the sediments, since consolidated oil shale is too color in a few days, but many years are required to alter com- impervious to permit circulation of carbonate solutions on large pletely the organic matter in the su1face coating. In fact, the scale. In many places calcite is later than dolomite and shows coating itself seems to prevent the continued penetration of complex crystallographic development in vugs and veinlets. the atmospheric weathei·ing (Guthrie, 1938, p. 98). Liquid or solid hydrocarbons locally accompany such calcite. Weathering of oil shales may, however, reduce its oil yield . Magnesite is not a common mineral. It has been noted as Several experimental sample results of this oil yield decrease clear, glassy crystals a centimeter across in the dolomitic rock have been reported. (Milton, 1957). · Oil shale ground approximately to a %-inch size and Albite is frequently found in high-grade oil-sbaJe beds, exposed to weathering for petiods up to six montlis did not especially near Rifle, Colorado. It appears most frequently as show a significant red1~ction in oil yield (Stanfield and others, simple rhomb-like crystals greatly flattened on (010 ). Meas- 1951). Sampling of oil-shale outcrops .indicates a different ured on the Jong diagonal, the maximum length of the crystals picture. Guthrie ( 1938) describes a case in which weathered is about 3 millimeters, but the average length is nearer to 0.15 sample yielded 12.8 gallons per ton, whereas a fresh sample millimeters. Frequent Roe Tournee twins are discemable. In- two feet deeper had an oil content of 45.5 gallons per ton. clusfons a.re abundant, and are commonly concentrated in a Thus, reserve calculations based upon surface sampling are not broad band along the short diagonal of the rhomb-like crystals. sufficiently reliable, and may tend to be rather conservative. They may be present in sufficient quantities to render the center of the crystal nearly opaque. The inclusions appear to Mineralogy be mainly carbonaceous matter, but mny also include mica flakes (Moore, 1950). Apparently the al bite is optically nega- In recent years, increased economic interest in oil shale tive, a property common to low-tempernture (authigenic) and trona deposits has stimulated detailed mineralogical studies varieties (Milton and others, 1960). A ftutbcr proof of authi- of the constituents o[ Lhe Green River formation, the lacustrine genic 01igin of albite is its sharp anguluity, which clearly and saline facies of which is composed p1:incipally of authigenic implies that the crystals have formed in place. minerals (Milton and Fahey, 1960). The l'ernarkable success achieved in this field can be best illustrated by the fact that The albite content of oil shales is directly propmtional to currently more than 50 autltigenic minerals have been recog- their content in organic matter. It is possible that the acids nized, compared to the six described by Bradley ( 1931) . Of produced by the decay of organic matter may have been an

Page 10 Colorado School of Mines important factor in causing the crystallization of nlbite. The and contain inclusions of minute irregular grains and rhombs of random arrangement of albite without reference to oil-shale carbonates and tiny flakes of clay minerals. Larger crystals have lmninne suggests that the enforgement of crystals occurred after been compressed to only half their normal diameter during the deposition. compaction of oil shale. These distorted crystals contain many Reetlmergn erite (NaBSi 3 0 ~ ), the boron analogue of albite, irregular cracks. These features seem to indicate that they is a new mineral, which has been reported up until now only were formed when the shale was only lightly buried. from the Uinta Basin. The formation may be explained by the Analcite is associated with dolomite, calcite, pyrite, following reaction: apophyllite, dawsonite, and many other minerals. According to Bradley ( 1929) , analci.te and apophyllite searlesite (NaBSi ~ O" · H 0) reedmergnerite 2 were formed at the lake bottom as a result of interactions + quartz + H 2 0 between dissolved salts and the dissolution products of volcanic It is indeed sb·iking to observe that reed.mergnerite is for ash. mot·e abundant than searlesite. Reedlnergnerite has been ten- Analcite is much more abundant than albite. From this tatively related to a rather extensive local foult system (Milton observation, Milton and others (1960) deduce that temperature and others, 1960) . and water pressures were not sufficient to permit the re- Microcline is present both as an authigenic and a elastic action mineral. Its presence in submicroscopically crystallized tuff analcite (NaA1Sip6 • Hp) <( albite (NaA1Sip8 ) beds bas been proven by x-ray diffraction studJes. Its petro- + Si02 + HP genic importance has been recently stressed (Milton and others, A remarkable feature of the Green River formation is the 1960). It seems conceivable that glnssy ash beds in contact presence of many uncommon saline sodium minerals, which with the lake waters altered to release sodium ions with fixa- are quite different from those encountered in typical salt de- tion of potassium in feldspar. If such a reaction would have posits. These unusual mineral assemblages are a direct conse- taken place on a large scale, it could explain the accumulation quence of special conditions prevailing during sedimentation of soda in the lake, the absence of significant amounts of and dingenesis, and the unusual composition of the waters in chloride, and the absence of potassium minerals other than which precipitation and the sedimentation took place (Milton stable feldspar. and Eugster, 1959). Pyrite is also a common mineral in the Green River forma- The distribution of saline minerals is not uniform through- tion, as well as in many other oil-shale districts. The greater out the whole formation, but considerable variations are in part of this mineral is present in subspherical grains that range existence from one basin to another. There is, for instance, an from 0.002 to about 0.005 millimeters in diameter. In some apparent incompatibility between trona, which is found mainly high-grade oil shales, there are numerous discoid aggregates in Lake Gosiute, and nahcolite, widespread in Lake Uinta of microgranuJar pyrite from 0.5 to 3 millimeters across. In under form of concretions and lenses. Under a given partial vertical section, the aggregates display n sort of laminated co" pressure, trona precipitates at a higher temperature than structure nnd the thin edges of successive dJscs inte~finger with nahcolite. However, a climatic difference between Lake Gosiute the microscopic oil-shale laminae. Often pyrite crystallizes in and Lake Uinta is not considered as a satisfactory explanation fern-like forms (Milton, 1957, fig. 7). lntergrowth of pyrite for the geographical aistributio11 of these two sodium carbon- and analcite is frequent. ates. Milton and Eugster (1959), who studied tbe different Pyrite was formed on the lake bottom contemporaneously sodium carbonate systems, come to the conclusion that Lake with the decay 0£ organic ooze while this was still soft. Hydro- Gosiute was more shallow than Lake Uinta. The brines in gen sulphide is a typical by-product of putrefactive processes, Lake Gosiute were saturated simultaneously over a great and forms iron sulphides by reaction with any iron salts dis- lateral extent, since trona forms a continuous bed which has solved in the lake water (Bradley, 1931). been recognized over more than 1,000 square miles. Brines in A similar origin of pyt·ite in the Lothian oil-shale field Lake Uinta were probably flooded by fresh water before trona (Scotland) was recently advocated by Greensmith ( 1957) . could form. Two forms of microfossils were isolated from the organic Detrital minerals matter, with a uni- or multi-cellular, microspinose and spherical appearance. The fossil affinities of these two forms are still The predominant detrital constituents of oil shales are doubtful, but it is hoped that further studies carried out on clay minerals and quartz. more samples will prove their organic origin ( Greensmith, Conflicting opinions on the role of clay minerals have 1957). been expressed. In older studies, their existence is mentioned, and they are described in detail. However, in a recent investi- Marcassite has been observed only in small quantities, and gation of numerous oil-shale samples in the Uinta Basin, in wurtzite is extremely rare. which x-ray diffraction, differential thermal analysis and chem- Quaitz is an ubiquitous mineral, but large crystals seem ical analysis methods were applied, the conclusion was reached to be very rare. Silicification, especially of outcropping beds, that three-fourths of the samples examined do not contain is frequently observed. Probably both the autltigenic and the any illite, montmorillonite or kaolinite (Hunt and others, 1954). elastic varieties are found, but their relative importance is Hence, further work on the clay mineralogy of the Green River difficult to ascertain, and has not been established as yet. formation seems advisable, as stressed by Milton and others Analcite, a zeolite, is by far the most widespread and ( 1960). abundant of the authigenic silicates. It is interesting to note Stevensite, a clay mineral of the montmorillonite gr:mp, is that whereas no other zeolite has been found in the Green reported from the Wilkins Peak Member of the Green River River formation, analcite is found in beds, up to several feet formation in Sweetwater County, Wyoming. This mineral is thick, and in lenses and disseminations. Many fine-grained the main constituent of an extensive bed, which is about four rocks, in which no analcite is discemable under the microscope, inches thick. The stevensite bed is light chocolate brown, show its presence in x-ray diffraction pattern. Analcite crystals probably owing to the 2.78 percent of organic matter it con- average about 0.065 millimeters in diameter, but range :from tains. Although the exact mode of formation of stevensite has 0.04 to 0.15 millimeters. They are clear and wholly isotropic, not been established as yet, it is considered to be of authigenic

Mineral Industries Bulletin Page l l Figure 6. Authigenic minerals in the Green River formation, from Milton and others, 1960. Species capitalized are unique to the Green River, and those in italics are known elsewhere only in igneous or metamorphic rocks.

Sulfides Oxides

Pyrite FeS2 Quartz Si02

Marcasite FeS2

Pyrrhotite Fe1 _xS Wurtzite ZnS

Carbonates

Calcite CaCO, Trana Na2 CQ3 ·NaHCQ3 ·2H2 0

Dolomite CaMg ( C03 ) 2 EITELITE Na2 Mg ( C03 ) 2 ) Siderite FeC03 Dawsonite Na3Al(C03 3 "2Al(OH)"

) ,, Magnesite MgC03 Burbankite Na2(Ca,Sr,Ba,Ca) 4 (C0,1

Witherite BaC03 SHORTITE Na2Ca2(C03)3 ) ) (?) "Alstonite-Bromlite" CaBa ( C03 2 Pirssonite N a2Ca (CO 3 2 ·2H20 ) ) Barytocalcite CaBa ( C03 2 Gaylussite Na2 Ca(C03 2 ·5Hp NORSETHITE ) Nahcolite NaHC03 BaMg ( CQ3 2 (NEW UNNAMED) Thermonatrite Na2 CO;H20 3NaHCOa·NacCO,

Carbonate-phosphates Carbonate-chlorides

BRADLEYITE Na3PO;MgC03 Northupite Na2 CQ3·MgCO" ·Na(:;

Silicates

3 Albite NaAISi3 0 8 Acmite NaFe+ Si2 0 6

Analcite NaAlSi2 0 6 "H20 Elpidite Na2 ZrSi.01 ;3H2 0 1 Sepiolite H 0Mg8 Si120 30 (OH) 10 "6H 2 0 M agnesioriebeckite ( crocidolite) , •I<" LOUGHLINITE Na2 Mg3Si60 16"8H2Q Na2 (Mg,Fe) 3 (Fe,Al) 2Sip22 (Oll) ., Labuntsovite (K,Ba,Na,Ca,Mn) Clay minerals

(Ti,Nb) (Si,Al) 2 (0,0H) 1 H 2 0 K-feldspar

Borosilicates

REEDMERGNERITE GARRELSITE ( NaBSi30 8 Ba,Ca,Mg) 2H 3 S.B,,< >_,, >•. ,. Searlesite NaBSi2 0 6 "H20 Leucosphenite CaBaNa, BTi3Si,,(

Phosphates Halides

) NEIGHBORITE Fluorapatite Ca10 (P04 6F 2 NaMgF3

Carbonate fluorapatite ( collophane) Cryolite N a3AIF 6 ) Ca10 (P04 .co3 ·H2 0 Halite

Sulfates

(?)Anhydrite CaS04 (?)Gypsum CaSQ4 ·2H20

(?) B.assanite CaSO,·JfH2 0 Barite BaSO 4

Celestite SrSO 4

Hydrocarbons Gilsonite, uintahite, utahite, tabbyite, ozokerite, ingramite, albertite, coal, etc.

"?" preceding mineral name indicates uncertainty as to its existence in the Green River. "Alstonite-bromlite" may be barytocalcite. Anhydrite, bassanite, and gypsum may have formed in the wet drill cuttings during storage.

Page 12 Colorado School of Mines origin. It was probably fotmed from a brine that was rich in It seems unlikely that uranium will be extracted as an magnesium-a short of residual brine in existence after much economic by-product from the western oil shales. of the trona had depos.ited out (Brad1ey, 1962 b, and Bradley Swanson reaches the conclusion that the small amounts of and Fahey, in press). uranium in the Green River oil shales are probably not asso- Qua:rtz has aheady been. described in the section on ciated genetically or chemically wi,th the abundant organic authigenic minerals. An undetenn.ined percentage of this matter present in these shales. In fact, the sapropelic type of mineral is of elastic origin. organic matter, mainly of algal origin, from which the western Other detrital minerals of subordinate importance are oil shales are said to be derived, does not assimilate uranium, strnicline, plagioclase feldspars, brown hornblende, muscovite, nor does it lend itself to decomposition by aneorbic bacteria zircon and apatite. A considerable pJ"Oportion of these minerals that would result in the acid and reducing environment of is of volcanic origin, and is brought into the basin of sedimenta- overlying waters favorable for uranium precipitation. tion by streams or by wind action (Bradley, 1931). According to Swanson, it seems unlikely that the uranium Trace elements in the Green River oil shales is contained in the resistates, in The following minor elements were detected by spectro- the clay fraction and in the volcanic tuff that is distributed graphic and chemical methods in different samples from the throughout the oil-shale bearing sequence. Mahogany ledge: Relatively high uranium contents are reported from Es- Minor elements in raw Colorado oil shale tonia and Sweden. The Estonian Dictyonema shale contains (maximum percent) from 0.005 to 0.025 percent of uranium, but only 10 to 13 gallons of oil per ton. However, plans to extract oil, uranium 0.001 Mo 0.001 Ag and phosphorite from these shales have been reported ( Kaelas, As 0.005 p 0.4 1957). Conversely, the overlying kukersite, which is mined Au 0.001 Pb 0.09 intensively because of its high oil content ( 50 gallons per ton 0.003 Se 0.001 B and more), contains less than 0.0001 percent of uranium. Ba 0.03 Sr 0.08 Cr 0.007 Ti 0. 06 In Sweden, kolm lenses, which are sparingly distributed Cu 0.008 TI 0. 7 throughout parts of the oil shales, contain up to 0.58 percent Li 0.05 v 0.06 of uranium (Swanson, 1960) .1 Mn 0.08 Zn 0.1 Source of data: Stanfield and others, 1951, p. 12. Texture It has been already pointed out that further studies of the With a few exceptions, beds of oil shale are thinly lam- distribution of trace elements are highly desirable. These studies inated. Generally, the thickness of the laminae decreases with should be carried out preferably on raw oil shal e.~. In fact, the increase of content of organic matter. Thus, laminae can the possibility of a certain amount of contamination from the be up to 0.5 millimeters thick in lean oil shales, but as thin metals and alloys of which the retorts are built cannot be as 0.014 millimeters in high-grade oil shales. Lamination is ruled out completely in spent shales. due to an alternation of layers rich and lean in organic matter. Shortly after World War I, some articles in technical and Bradley's interpretation of these laminae as varves has been b·ade papers inferred that several precious metals such as gold, widely accepted. Thefr bipartite stmct:ure is explained in part silver and platinum could be successfully extracted from oil by the differential settling of the two groups of constituents and shales. The U. S. Bureau of Mines examined the possibility of in prut by assuming essentially continuous sedimentation of the recovering gold, and came to the conclusion that only a small mineral and organic constituents, with first a peak in the pro- amount of gold contained in crude oil shale can be Tecovered duction of the carbonates and then a peak in that of the by cyanidation and chlorination, an.cl that consequently the plankton. Both peaks apparently occurred in summer. On the proposition was not commercially feasible (Varley, 1922). basis of the varves, it has been estimated that the Green River Several studies on content and origin of ma11i.um in oil epoch lasted between 5,000,000 and 8,000,000 years (Bradley, shales were carried out in recent years. In the eastern and 1929c and 1931). central U11ited States, the Chattanooga marine oil shale, of Contorted bedding is common in the Green River forma- Devonian-Mississippian age, was particularly studied (Swanson, tion, and is generally more common in high-grade oil shales. 1960 and 1961; Landis, in press; Hyden and Danilchik, in The flexures in the rich oil shales range in complexity from press). rather simple folds whose axial planes are considerably in- The average uranium content of all shales is estimated clined to the vertical, through large overfolds upon which to be between 0.0003 and 0.0004 percent ( 3 to 4 parts per one or two sets of minor folds are imposed, to extremely intri- million), approximately the same as for granites. The Chat- cate plications and long overthrusts whose thrust planes un- tanooga shale is considerably richer, as it contains an average dulate. Practically all the deformation in these beds occurred of 0.003 percent of uranium, whereas the average uranium when the material was plastic enough to yield readily without content of the Mahogany ledge, the part of the Green River fracturing, and yet firm enough to retain its form after defo1ma- formation with the highest oil yields, is only 0.0006 percent. tion. Contorted bedding has been explained by differential However, abnormally high concentrations of syngenetic movements and readjustments within and between the beds uranium associated with phosphorus have been briefly reported after burial and during compaction (Bradley, 1931). from the partially lacustrine Wilkins Peak member of the Oil shale breccias of two types are frequent. In the first Green River formation in Wyoming. A 3-inch brown oil shale type, coarse fragments of both oil shale and marlstone are averages 0.012 percent U and 8.1 percent P2 0 0 along 18 generally oriented at appreciable angles to the bedding. In outcrop miles (five sections studied). Maximum values in this 1Kolm, a Scandinavian term, can be defined as a variety of bed are 0.019 percent U and 12.9 percent P2 0;,. Uranium varies coal occurring locally as lenticles in Swedish oil shales and con- with phosphorus and replaces calcium ions in carbonate taining about 30 percent of ash. Kolm is remarl

Mineral Industries Bulletin Page 13 the second type, small flakes of richer oil shales are contained Formation of these breccias has been explained by partial in oil shale beds, and are oriented nearly parallel to the lamina- emersion of oiJ shale beds, dessication and consequent sun- tion of the bed which contains them. This particular type of cracking nn.d scaling. This hypothesis is strengthened by the breccia, which is mor~ ah11ndant than the first one, is termed fact that mud cracks which show a mosaic brecciation have as mosaic breccia. been 0bserved frequently.

BI BLIOCRAPHY Caroz:ir..i, A. V., 1960, ?vlioroscopic sedimentary petrography: New York and Loudon, John Wiley & Sons, Inc., 485 p. Abbott, W., 1957, The Tertiary of the Uinta basin in Inter- mountain Assoc. Petroleum Geologists, 8th Annual Field Cashion, W. B., 1957, Stratigraphic relation and oil shale of Conf., Guidebook to the geology of the Uinta basin, p. the Green River formation in the eastern Uinta basin in 102-109. lntermountain Assoc. Petroleum Geologists, 8th Annu;1) Baker, J. H., 1959, Mining by hydraulic jet: Mining Congress Field Conf., Guidebook to the geology of the Uinta basin, Jour., v. 45, no. 5, p. 45-46, 52. p. 131-135. Barb, C. F., and Ball, J. 0., 1944, Hydrocarbons of the Uinta ...... ·- --., 1959, Geology and oil-shale resources of Naval basin of Utah and Colorado: Colorado School of Mines Oil-Shale Reserve No. 2, Uintah and Carbon Counties, Quart., v. 39, no. 1, 115 p. Utah: U. S. Geol. Survey Bull. 1072-0, 40 p. Belser, C., 1949, Oil shales resources of Colorado, Utah and Cashion, ·w. B., and Brown, J. H., Jr., 1956, Geology of the Wyoming: Am. Inst. Mining Metal!. Engineers Trans., Bon11.nza-Dragon oil-shale area, U.intah County, Utah, and v. 179, p. 72-82. Rio Blanco County, Colorado: U. S. Geol. Survey Oil and Gas Inv. Map OM-153. Bradley, W. H., 1929a, Algae reefs and ooliths of the Green River formation: U. S. Geol. Survey Prof. Paper 154-C, Conant, L . C., and Swanson, V. E., 1961, Chattanooga shale p. 203-223. and related rocks of central Tennessee and 11earby areas: ...... , 1929b, Occurrence and origin of analcite and U.S. Ceo!. Survey Prof. Paper 357, 91 p . meerschaum beds in the Green River formation of Utah, Crawford, A. J., 1961, Oil shale on Ch~·is's Creek, Juab Coµnty, Colorado, and Wyoming: U. S. Geol. Survey Prof. Paper Utah; The mystery of the legendary first retort: Utah Ceol. 158, p. 1-7. and Milleral. Survey Circ. 41, 26 p. 1929c, The varves and climate of the Green River epoch: U. S. Geol. Survey Prof. Paper 158, p. 87- Crowley, A. J., 1957, The tectonic history of the Uinta Basin 110. in Iutexmountain Assoc. Petroleum Geologists, 8th Annual Field Conf., Guidebook to the geology of the Uinta Basin, ...... _ ...... , 1931, Origin and microfossils of the oil shale p. 25-29. of the Green River formation of Colorado and Utah: U. S. Geol. Survey Prof. Paper 168, 58 p. Culbertson, W. C., 1961, Stratigraphy of the Wilkins Peak member of the Green River formation, Firehole Basin ...... , 1936, The biography of an ancient American quadrangle, Wyoming: U. S. Geol. Survey Prof. Paper lake: Sci. ivlonthly, v. 42, p. 421-430. 424-D, p. Dl70-Dl73. 1948, Limnology of the Eocene lakes of the Cunningham-Craig, E. H., 1929, The origin and constitution Rocky Mountain region: Geol. Soc. of America Bull., v. of oil shale with a practical appucation: World Eng. Cong. 59, no. 7, p. 643. Proc., p. 1-25. 1959, Revision of stratigraphic nomenclature of Donnell, J. R., 1961, Tertiary geolog)' and oil-shale resources Gi:een River formation in 'Wyoming: Am. Assoc. Peh·oleum of the Piceauce Creek basitl between the Colorado and Geologists Bull., v. 43, p. 1073-1075. vVhite Rivers, northwestern Colorado: U. S. Geol. Survey Bull. 1082-L, 56 p ...... , 1961, Geological map of a part of southwestern Wyoming and adjacent states: U. S. Geol. Survey Misc. 1962, U. S. Geol. Survey, Denver, personal Geol. Inv. Map. I-332. communication. · 1962 a, Chloroplast in Spirogyra from the Green Donnell , R., Cashion, W. B., and Brown, H., Jr., 1953, River formation of Wyoming: Am. Jour. Sci., vol. 260, J. J. Geology of the Cathedral Bluffs oil-shale area, Rio Blanco p. 455-459. and Garfield Counties, Colorado: U. S. Geol. Survey Oil 1962 b, U. S. Geol. Survey, Washington, per- and Gas Inv. Map OM-134. sonal communication. Bradley, W. H., and Fahey, J. J., in press, Occurrence of Duncan, D. C., 1958, Known reserves, oil-shale deposits in stevensite in the Green River formation in Wyoming: Am. the United States: Independent Petroleum Assoc. of Mineralogist. America Monthly, v. 29, no. 4, p. 22, 49-51, August. Brongersma-Sanders, M., 1957, Mass mortality in the sea in Duncan, D. C., and Denson, N. M., 1949, Geology of the Treatise on marine ecology and paleontology, Volume 1: Naval Oil-Shale Reserve No. I and 3, Garfield County, Ecology, Geol. Soc. America Mem. 67, Chap. 29, p. 941- Colorado: U. S. Ceo!. Survey Oil and Gas Inv. Prelim. 1010. Map 94.

Page 14 Colorado School of Mines Durham, 0. C., 1942, Air-borne fungus spores as allergens in LaRoque, J. A. A., 1956, Tertiary mollusks of central Utah in Aerobiology: Am. Assoc. Adv. Sci., Pub. 17, p. 42-44. Interrnountain Assoc. Petroleum Geologists, 7th Annual Field Conf., Guidebook, East Central Utah, p. 140-145. Ertl, T., 1947, Sodium bicarbonate (nahcolite) from Colorado oil shale: Am. Mineralogist, v. 32, p. 117-120. Lehnhardt, W. B., 1958, Pipe line licks rock haulage problem: Rock Products, p. 106-109, March. ··-··········- ········,1955, Colorado oil shale, its geology and economic significance: Tulsa Geol. Soc. Digest, v. 23, p. 98- Love, J. D., in press, Lacustrine uraniferous phosphatic strata 106. of Eocene age in southwestern and central Wyoming, with notes on similru· occun·ences in the Uinta Basin, Utah, and 1962, Vice President, Cameron and Jones, Inc., other areas: U. S. Geol. Survey Prof. Paper. Denver, persoual communication. Love, J. D., and Milton, Ch., 1959, Uranium and phosphate Fahey, J. J., 1962, Saline minerals of the Green River forma- in the Green River formation of Wyoming: Geol. Soc. tion: U. S. Geol. Survey Prof. Paper 405, 50 p. America Bull., v. 70, p. 1640.

Gazin, C. L., 1959, Paleontological exploration and dating of Luts, K., 1938, The occurrence and application of kukersite in the early Tertiary deposits in basins adjacent to the Uinta Estonia, with particular reference to the Plant of the A/G Mountains in Intermountain Assoc. Petroleum Geologists, "Esirnene Polevkivitoostus" (First Estonian Oil Shale In- lOth Annual Field Conf., Guidebook to the geology of the dustry) in Oil shale and cannel coal: London, Inst. of Wasatch and Uinta mountains, p. 131-138. Petroleum, v. 1, p. 124-142. Glass, J. J., 1947, Sodium bicarbonate (nahcolite) from Gar- Mannion, L. E., and Jefferson, G. L., 1962, An outline of the field County, Colorado: Am. Mineralogist, v. 32, p. 201. geology of the Wyoming trona beds: Paper presented to the Pacific Southwest Mineral Industry Conf., AIME, San Greensrnith, J. T., 1957, Lothian oil shale field: Petroleum, v. Francisco, April 12-14, 8 p. 20, p. 439-442. Masursky, H., in press, Uranium-bearing coal in the eastern 1961, Oil shales, review of present economic part of the Red Desert area, Great Divide Basin, Sweet- and geological status: Petroleum, v. 24, p. 87-89. water County, Wyoming: U.S. Geol. Survey Bull. 1099-B. Guthrie, B., 1938, Studies of certain properties of oil shale and Masursky, H., and Pipiringos, G. N., 1959, Uranium-bearing shale oil: U. S. Bur. Mines Bull. 415, 159 p. coal in the Red Desert area, Sweetwater County, Wyo.: U. S. Geol. Survey Bull. 1055-G, p. 181-215. Hartley, F. L., and Brinegar, C. S., 1959, Oil shale-energy for the future: Fifth World Petroleum Cong. Proc., Sec. McGrew, P. 0., and Berman, J. E., 1955, Geology of the II, p. 37-47. Tabernacle Butte area, Sublette County, Wyoming, in Wyoming Geol. Assoc., lOth Annual Field Conf., Guide- Hunt, J. M., Stewart, F., and Dickey, P. A., 1954, Origin of book, Green River Basin, p. 108-111. hydrocarbons of Uinta basin, Utah: Arn. Assoc. Petroleum Geologists Bull., v. 38, no. 8, p. 1671-1698. Milton, Ch., 1957, Authigenic minerals of the Green River formation of the Uinta basin, Utah in Interrnountain Assoc. Hyden, H. J., and Danilchik, W., in press, Uranium in some Petroleum Geologists, 8th Annual Field Conf., Guidebook rocks of Pennsylvanian age in Oklahoma, Kansas and Mis- to the geology of the Uinta Basin, p. 136-143. souri: U. S. Geol. Survey Bull. 1147-B. Milton, Ch., Chao, E. C. T., Fahey, J. J., and Mrose, M. E., Jaffe, F. C., 1962, Oil shale. Part I. Nomenclature, uses, re- 1960, Silicate mineralogy of the Green River formation serves and production: Colorado School Mines Mineral of Wyoming, Utah, and Colorado in 2lst Internat. Geol. Industries Bull., v. 5, no. 2, 11 p. Cong., Pait 21, Copenhagen, p. 171-184. Jones, D. J., 1957, Geosynclinal nature of the Uinta Basin in Milton, Ch., and Eugster, H. P., 1959, Mineral assemblages Interrnountain Assoc. Petroleum Geologists, 8th Annual of the Green River formation in Researches in Geochem- Field Conf., Guidebook to the geology of the Uinta Basin, istry: New York, John Wiley and Sons, Inc., p. 118-150. p. 30-34. (Abelson, Ph. H., ed.) Kaelas, A., 1957, The Estonian oil shale industry: Inst. for the Milton, Ch., and Fahey, J. J., 1960, Green River mineralogy Study of the USSR Bull., v. 4, no. 11, p. 32-37. -an historical account in Wyoming Geol. Assoc., 15th Annual Field Conf. Guidebook, Overthrust Belt of south- Kay, L. J., 1957, The Eocene vertebrates of the Uinta Basin, western Wyoming and adjacent areas, p. 159-162. Utah, in Interrnountain Assoc. Petroleum Geologists, 8th Annual Field Conf., Guidebook to the geology of the Moore, F. E., 1950, Authigenic albite in the Green River oil Uinta Basin, p. 110-114. shales: Jour. Sed. Petrology, v. 20, p. 227-230. Kennedy, W. Q., 1943, The oil-shales of the Lothians-Strncture Oriel, S. S., 1961, Tongues of the Wasatch and Green River -Area IV, Philipstoun: Geol. Survey of Great Britain, formations, Fort Hill area, Wyoming: U. S. Geol. Survey Wartime Pamphlet No. 27, 36 p. Prof. Paper 424-B, p. Bl51-Bl52. Landis, E. R., in press, Uranium and other trace elements in Picard, M. D., 1955, Subsurface stratigraphy and lithology of Devonian and Mississippian black shales in the central Green River formation in Uinta Basin, Utah: Am. Assoc. Midcontinent area: U. S. Geol. Survey Bull. 1107-E. Petroleum Geologists Bull., v. 39, no. 1, p. 75-102.

Mineral Industries Bulletin Page 15 1957, Green River and lower Uinta formations Thorslund, P., and Jaanusson, V., 1960, The Cambrian, Ordo- -subswface stratigraphic changes in central and eastern vician and Silurian in Viistergotland, Niil'ke, Dalarna and Uinta basin, Utah, in Intermountain Assoc. Petroleum Ge- Jamtland, Central Sweden: 2lst Internat. Geol. Cong., ologists, 8th Annual Field Conf., Guidebook to the geology Guide to excursions Nos. A 23 and C 13, 51 p. of the Uinta Basin, p. 116-130. Tiratsoo, E. N., 1951, Petroleum geology: London, Methuen Pipiringos, G. N., 1955, Tertiary rocks in the central part of and Co., Ltd., 449 p. the Great Divide Basin, Sweetwater County, Wyoming in Wyoming Geol. Assoc., lOth Annual Field Conf., Guide- Tracey, J. I., Jr., and Oriel, S. S., 1959, Uppermost Cretaceous book, Green River Basin, p. 100-104. and lower Tertiary rocks of the Fossil Basin in Intermoun- tain Assoc. Petroleum Geologists, lOth Annual Field Conf., 1961, Uranium-bearing coal in the central part Guidebook to t11 e geology of the Wasatch and Uinta of the Great Divide Basin: U.S. Geol. Survey Bull. 1099-A, :!'.fountains, p. 126-130. 104 p. Untermann, G. E. and B. R., 1961, Geological map of Uintah Pruitt, R. G., Jr., 1961, The mineral resources of Uintah County: County, Utah (north half): Utah Geol. and Mineral. Utah Geol. and Mineral. Survey Bull. 71, 101 p. Survey. Rice, C. M., 1940, Dictionary of geological terms: Ann Arbour, Untermann, G. E. and B. R., and Kinney, D. M., 1961, Geo. Mich., Edwards Brothers, Inc., 463 p. logical map of Uintah County, Utah (south half): Utah Geol. and Mineral. Survey. Stanfield, K. E., Frost, I. C., McAuley, W. S., Smith, H. N., 1951, Properties of Colorado oil shale: U. S. Bur. Mines U. S. Bureau of Mines, 1960, Oil shale in Mineral facts and Rept. Inv. 4825, 28 p. problems: U. S. Bur. Mines Bull. 585, p. 573-580. Stanfield, K. E., Rose, C. K., McAuley, W. S., and Tesch, Varley, Th., 1922, Bureau of Mines investigates gold in oil W. J., Jr., 1957, Oil yields of sections of Green River oil shales and its possible recovery: U. S. Bur. Mines Rept. shale in Colorado, 1952-1954; U. S. Bur. Mines Rept. Inv. Inv. 2413, 10 p. 5321, 132 p. Veatch, S. C., 1907, Geography nnd geology of a portion of . Stanfield, K. E., Smith, J. W., Smith, H. N., and Robb, W. A., southwestern \.Vyoming, with special reference to coal and 1960, Oil yields of sections of Green River oil shale in oil: U. S. Geol. Smvey Prof. Paper 56, 178 p. Colorado, 1954-1957: U. S. Bur. Mines Rept. Inv. 5614, 186 p. von Winkler, H., 1930, Der Estliindische Brennschiefer, Reval, Wassermann, 350 p. Stokes, Wm. L., and Madsen, J. H., Jr., 1961, Geologic map of Utah, northeast corner: Utah Geol. and Mineral. Survey. Wetzel, W., 1947, SecHm entpetrographische Studien der kam- brosilmischen Ablagerungen des Billingen: Deutsche geol. Swain, F. M., 1956, Early Tertiary ostracode zones of the Gesell. Zeitschr., v. 99, p. 139-149. Uinta Basin in Intermountain Assoc. Petroleum Geologists, 7th Annual Field Conf., Guidebook, East Central Utah, Winchester, D. E., 1916, Oil shales in northwestern Colorado p. 125-139. and adjacent areas: U. S. Geol. Survey Bull. 641, p. 139- 198. Swanson, V. E., 1960, Oil yield and uranium content of black shales: U. S. Geol. Survey Prof. Paper 356-A, 44 p. ------····-·········-,1918, Oil shale of the Uinta Basin, northeast- ern Utah: U. S. Geol. Survey Bull. 691 (b), p. 27-50. 1961, Geology mid geochemistry of uranium in marine black shales. A review: U. S. Geol. Survey Prof. ·····················---,1923, Oil shale of the Rocky Mountain region: Paper 356-C. U. S. Geol. Survey Bull. 729, 204 p.

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