Journal of Paleolimnology 30: 115–125, 2003. 115 © 2003 Kluwer Academic Publishers. Printed in the Netherlands.

Lake basin response to tectonic drainage diversion: ,

Jeffrey T. Pietras*, Alan R. Carroll and Meredith K. Rhodes Department of Geology and Geophysics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; *Author for correspondence (e-mail: [email protected])

Received 10 August 2001; accepted 11 December 2002

Key words: , Lacustrine, Sequence boundary, Tectonic control,

Abstract

A previously unidentified major sequence boundary within the Eocene Green River Formation separates fluctuat- ing profundal facies of the Tipton Shale Member from evaporative facies of the Wilkins Peak Member. During deposition of the Tipton Shale Member, rivers entered the basin from the north, across the subdued Wind River Mountains, and deposited the southward prograding deltaic complex of the Farson Sandstone Member. Boulder- rich alluvial fan deposits overlie the Farson Sandstone adjacent to the Continental Fault, and correlate basinward to hypersaline lacustrine deposits of the Wilkins Peak Member. The alluvial fan deposits record a period of reverse motion on the Continental Fault and uplift of the southeastern , which diverted drainage away from the greater Green River Basin. This decreased inflow caused Lake Gosiute to shrink, exposing its bed to desiccation and erosion, and contributed to hydrologically-closed conditions and periodic evaporite deposition thereafter. This study is one of the first to demonstrate a direct relationship between movement along a specific basin-bounding structure, and a change in the overall style of lacustrine sedimentation. The identification of simi- lar relationships elsewhere may challenge conventional interpretations of climate as the dominant factor influenc- ing the character of lake deposits, and provide an important, but previously unexploited, approach to interpreting continental deformation and regional drainage organization.

Introduction controls on lacustrine stratigraphy remains very poorly developed relative to marine systems. In addition, cli- Lacustrine strata of long-lived lakes fundamentally mate is conventionally perceived to be the principal record impoundment of paleo-drainage systems due to control on lacustrine sedimentation. For example, cy- tectonic subsidence or uplift, and therefore offer unique clic packages of Quaternary lacustrine strata resulting and potentially important records of continental defor- from rapid lake level fluctuations are commonly inter- mation. However, these records are rarely so exploited, preted to result from climatic forcing (e.g., Benson, due largely to the fact that our understanding of the 1981; Owen et al., 1990; Oviatt, 1997). These obser- vations have been used to infer that cyclic stratigraphy in more ancient deposits was also forced by orbitally- driven climatic perturbations (e.g., Olsen, 1986; Roehler, 1993; Benson, 1999), even in the numerous cases where *This is the first in a series of four papers published in this issue independent chronological evidence supporting this collected from the 2000 GSA Technical Session ‘Lake basins as interpretation does not exist. archives of continental tectonics and paleoclimate’ in Reno, . Furthermore, the basin-scale occurrence of evap- This collection is dedicated to Dr. Kerry R. Kelts; Drs. Elizabeth Gierlowski-Kordesch and H. Paul Buchheim were the guest editors orites is commonly attributed to longer-term changes of this collection. in precipitation vs. evaporation and transpiration (e.g.,

Castlefield Press: JOPL 900, CP, typeset, disc, Pips no.: 5119286 116

Langbein, 1961; Roehler, 1993; Gómez-Fernández and 2) consists of a mix of sedimentary facies, recording Meléndez, 1994). However, there is little correlation deposition in freshwater to hypersaline phases of Eocene between precipitation/evaporation and any measure of Lake Gosiute (Culbertson, 1969; Hanley, 1976; Sur- lake size (Carroll and Bohacs, 1999) or chemistry dam and Stanley, 1979; Surdam and Stanley, 1980; (Bohacs et al., 2000) for modern lakes. Recent studies Smoot, 1983; Roehler, 1991; Bohacs, 1998; and refer- suggest that relatively subtle tectonic activity along key ences therein). Continuous exposures of lacustrine and drainage divides can exert a first order control on ba- associated alluvial strata west and north of the Rock sin hydrology, and consequently on evaporite deposi- Springs Uplift (Figure 1) permit the identification, and tion (e.g., Kowalewska and Cohen, 1998; May et al., direct correlation, of stratal boundaries between lac- 1999; Sáez et al., 1999). Yet, none of these studies have ustrine facies associations near the basin center and documented the detailed relationship between specific syntectonic alluvial strata deposited at the basin mar- tectonic events and basin stratigraphy. gin. In this paper, we describe a lacustrine sequence The greater Green River Basin (Figure 1) of south- boundary that separates the Tipton Shale Member from western Wyoming provides an excellent opportunity to the overlying Wilkins Peak Member, and the relation- examine these detailed relationships, due to its continu- ship of this surface to the structural evolution of a major ous outcrop exposures and to the abundance of pre- basin-bounding uplift. This paper aims to directly test vious studies of nonmarine sedimentary facies and the influence of a specific Laramide structural event on regional tectonics. The Green River Formation (Figure lake type evolution.

Figure 1. Location of measured sections RS – Rock Springs, BG – Breathing Gulch, BT – Boar’s Tusk, and WC – Whitehorse Creek within the greater Green River Basin. Maximum extent of individual members of the Green River Formation from Bradley and Eugster, 1969; Roehler, 1992b. Base map modified from Mallory, 1972. 117

Figure 2. Cross section A-A’ showing the regional stratigraphy of the greater Green River Basin, and the unconformable relationship be- tween the Tipton Shale and Wilkins Peak members (modified from Roehler, 1991). See Figure 1 for location. Lake-basin types from Carroll and Bohacs (1999) OF – overfilled, BF – balanced fill, UF – underfilled.

Geologic setting Lake Gosiute is interpreted to have been a freshwater lake. The Luman Tongue is separated from the rest the The greater Green River Basin (Figure 1) was part of Green River Formation by the overlying Niland Tongue the foreland that formed adjacent to the Sevier Thrust of the . The remaining three mem- Belt during late time. Final Sevier thrusting bers directly overlie one another, and record the shift occurred during the late Paleocene and early Eocene in deposition in freshwater lakes (Tipton Shale Mem- along the Hogsback Thrust at the western border of ber), to evaporative lakes (Wilkins Peak Member), and the basin (DeCelles, 1994). This foreland was subse- then back to freshwater conditions in the Laney Mem- quently subdivided by basement cored block uplifts ber (Hanley, 1976; Roehler, 1992a; Roehler, 1993). of the during the (Bell, 1954; Anderman, 1955; Keefer, 1965; Love, 1970; Dorr et al., 1977; Gries, 1983; Steidtmann et al., 1983; Roehler, Tipton Shale Member: overfilled to balanced fill 1992b). The Laramide Wind River and Uinta moun- basin tains, bordering the basin to the north and south respec- tively, were uplifted along reverse faults shown to The Tipton Shale Member is divided into the Scheggs cross cut parts of the Eocene Green River Formation Bed and partly correlative Farson Sandstone Member, (Steidtmann et al., 1983; Roehler, 1993). and the Rife Bed (Figure 2). The base of the Tipton The Green River Formation (Hayden, 1869) records Shale Member is marked by an erosional scour. Sand- four major phases of Eocene Lake Gosiute, represented stone beds that overlie this surface near the basin center by the Luman Tongue, Tipton Shale Member, Wilkins grade laterally into pebble conglomerate beds at the Peak Member, and the Laney Member (Figure 2). These basin margin (Figure 3). Fissile organic-rich calci- lacustrine strata grade laterally into the alluvial Wasatch micrite () and fish typify both the Formation. During deposition of the Luman Tongue, Scheggs and Rife beds (Culbertson, 1969). However, 118

Figure 3. Correlation of measured sections across the Tipton Shale/Wilkins Peak contact showing the progradational geometry of the Farson Sandstone Member, and details along the sequence boundary. See caption on Figure 1 for localities. the freshwater Pisidiidae-Goniobasis-Valvata mollusk Creek, this interval consists of planar-laminated, fine- association of Hanley (1976) is abundant only in the grained sandstone and muddy-sandstone beds inter- Scheggs Bed, suggesting that conditions in the lake preted as topsets of a delta plain facies association. became more saline during deposition of the Rife Bed. The progradational geometry of the Farson deltas, The Farson Sandstone Member (Roehler, 1991) is in- and the presence of a freshwater fauna suggest that terpreted as deltaic and lake-margin deposits that the basin was overfilled during the deposition of the generally prograded into Lake Gosiute from the north Scheggs Bed. In contrast, the trend to more saline con- during deposition of the Scheggs Bed. It is mapped ditions in the overlying Rife Bed suggests an intermit- across the entire southern margin of the Wind River tent closed hydrology lending evidence for balanced fill Mountains, extending southward to the center of the conditions (cf. Carroll and Bohacs, 1999). greater Green River Basin (Figure 1). The stratal ge- ometries of two sandstone intervals observed within the Farson Sandstone Member record progradation to the Wilkins Peak Member: underfilled basin southwest (Figure 3). The lower interval consists of fine-to-medium-grained sandstone deposited as south- Lithologies in the Wilkins Peak Member (Bradley, 1959) westward dipping deltaic foresets with approximately include tan to olive marlstone, organic-rich calcimicrite, 15 m of relief, indicating water depths of at least this thin calcareous sandstone beds, arkosic sandstone beds, great recorded in the Whitehorse Creek section (Fig- and bedded and halite (Bradley and Eugster, 1969; ure 4). Individual clinoforms can be correlated down Culbertson, 1969; Smoot, 1983). During extended lake dip to very-fine-grained sandstone beds with abundant lowstands the basin center was the site of a playa where gastropods, and up dip to thin pebble lags composed 25 evaporite beds (thicker than 1 m) were deposited mainly of quartz, chert, schist, and gneiss (McGee, ranging from 427–1,870 km2 in extent (Bradley and 1983; Pietras et al., 2000). Deposition of the upper Eugster, 1969). Fossils representing a freshwater fauna, interval extended farther southwest, as far south as the such as fish or gastropods, are absent in the Wilkins Peak Breathing Gulch section (Figure 3). At Whitehorse Member, supporting the interpretation of hypersaline 119

Figure 4. Farson Sandstone Member delta at Whitehorse Creek. Foresets dip to the left (southwest), and are 15 m thick on the far left of the photo. See location of this outcrop in Figure 7. conditions inferred from the presence of evaporite de- Basal Wilkins Peak Member sequence boundary posits. Insect remains are the only common macro- scopic fossils observed. The Wilkins Peak Member and laterally equivalent Ca- The presence of numerous desiccation surfaces and thedral Bluffs Tongue unconformably overlie the Rife bedded , suggest that the Wilkins Peak Mem- Bed of the Tipton Shale Member (Figure 3). This con- ber was deposited in an underfilled basin (Carroll and tact is abrupt across the study area, and marked by Bohacs, 1999). subaerial erosion. Decimeter-scale scour into profundal The Wilkins Peak Member thins northward and inter- facies of the Rife Bed marks the contact in the Rock fingers with the Cathedral Bluffs Tongue of the Wasatch Springs section (Figure 5C). Here, a thin, very-fine- Formation (Figure 3). In the Whitehorse Creek section, grained sandstone bed of the Wilkins Peak Member the Cathedral Bluffs Tongue is composed of red and infills the scour, and contains rip-ups of the underly- green silty-mudstone with a basal pebble layer (Figure ing organic-rich calcimicritic Rife Bed. Mudcracks are 5A) and rare well-rounded granitic boulders (Figure present along this contact northward at both the Breath- 5B). These alluvial deposits coarsen northward rapidly ing Gulch and Boar’s Tusk sections (Figure 5D). A 1 into an angular boulder-rich conglomerate that is inter- m thick bed was deposited on this surface preted to be part of an alluvial fan complex (McGee, in the Breathing Gulch section during initial transgres- 1983). This conglomerate facies reaches approximately sion of the Wilkins Peak Member. Concurrently, a thin 60 m in thickness on Pacific Butte (Figure 6) before very-fine-grained sandstone bed overlain by a 1 cm terminating along the Continental Fault. The lateral thick oolite bed was deposited in the Boar’s Tusk sec- extent of coarse-grained material is restricted to Pacific tion. Along the northern basin margin, at Whitehorse Butte and a similar butte to the east where the conglom- Creek, the Cathedral Bluffs Tongue overlies the Rife erate facies is approximately 120 m thick (Figure 6). Bed. Here, the contact is marked by meter-scale inci- The surface of both buttes dips southwestward at ap- sion, and is overlain by a pebble conglomerate that proximately 5°. We interpret them as exhumed Eocene grades upward into silty-mudstone (Figure 5A). alluvial fans. We interpret the contact between the Tipton Shale 120

Figure 5. (A) Mudstone of the Tipton Shale Member unconformably overlain by pebble conglomerate of the Cathedral Bluffs Tongue and Whitehorse Creek section. (B) Well-rounded granitic boulder at the base of the Cathedral Bluffs Tongue at Whitehorse Creek approximately 1 m in diameter. (C) Tipton Shale/Wilkins Peak sequence boundary at Rock Springs section marked by sandstone filled scour into oil shale. (D). Mudcrack casts at the base of the Wilkins Peak Member at Breathing Gulch section. Specimen is 50 cm across.

Figure 6. Geologic map of the Whitehorse Creek section and surrounding features. Note the presence of two ‘exhumed’ alluvial fans termi- nating along the trace of the Continental Fault. See Figure 1 for location. Modified from Zeller and Stevens (1969). 121 and Wilkins Peak members as a sequence boundary; igraphic patterns and potassium-argon dates (Mauger, based on the observation that it is an unconformable 1977) of interbedded volcanic tuffs. They showed that surface that separates two genetically unrelated pack- evaporite deposition occurred synchronously between ages of rock (Mitchum et al., 1977; Van Wagoner et al., the Piceance Creek Basin and the Wilkins Peak Mem- 1988). This surface thus marks a fundamental shift in ber, however evaporite deposition in the the style of sedimentation in Lake Gosiute from over- occurred later. Smith (2002) confirmed this correlation filled to underfilled deposits. based on high precision 40Ar/39Ar of the same volcanic tuffs. It is likely that Eocene climate for these basins was similar based on their proximity, how- Discussion ever the long-term lake type fluctuated independently. A modern analogue to this situation is represented by Previous workers have inferred that evaporite deposi- Lake and Great Salt Lake. Separated by only 50 km, tion in the Wilkins Peak Member occurred due to a both are within the same climate regime, however Utah long-term shift to a hotter and drier climate (Bradley Lake is a freshwater lake that drains into the hypersaline and Eugster, 1969; Roehler, 1993). Studies based on Great Salt Lake. Combined, these observations suggest crocodilian distribution (Markwick, 1994), leaf-mar- that factors other than regional climate controlled long- gin analysis (Wolfe, 1978; Wing and Greenwood, 1993; term lake type. Wilf, 2000), and mean leaf area (Wilf et al., 1998; Wilf, Alternatively, the Tipton Shale-Wilkins Peak se- 2000) have produced mean annual temperature (MAT) quence boundary can be explained by tectonic reorgani- estimates of 19–23 ºC, and mean annual precipitation zation of the Lake Gosiute drainage basin in response (MAP) of 75–150 cm/yr for the area during deposition to renewed uplift of the southern Wind River Moun- of the Green River Formation. The paleotemperature tains along the Continental Fault (Figure 1). The most estimates, associated with deposition in Eocene Lake recent movement of the Continental Fault was exten- Gosiute, are warmer than the conditions determined for sional, resulting in a Neogene graben (Love, 1954; Zeller the underlying Paleocene fluvial and alluvial depos- and Stephens, 1969; Steidtmann and Middleton, 1991). its of the Fort Union and Wasatch formations (~12– However, this fault has been interpreted as an Early 19 ºC). This observation is consistent with global Eocene reverse fault, up thrown to the north, based on proxies of paleoclimate that suggest the early Eocene the association with the nearby Wind River thrust sys- was the warmest period during the Cenozoic (Zachos tem and the shift in sedimentation from the deltaic et al., 2001). However, detailed evidence for climate Farson Sandstone Member to the overlying alluvial fan change across the Tipton-Wilkins Peak boundary is deposits of the Cathedral Bluffs Tongue (McGee, 1983; equivocal at best. Only two floral assemblages con- Steidtmann et al., 1983; Steidtmann and Middleton, strain the boundary. The lower assemblage was collected 1991). As seen on Figures 6 and 7, the surface trace of from the Niland Tongue of the Wasatch Formation, lo- the Continental Fault at Whitehorse Creek is just 2.5 km cated stratigraphically below the Tipton Shale Mem- north of Reds Cabin Monocline, which formed in re- ber (Figure 2; Wilf, 2000). The upper assemblage was sponse to thrusting along the buried Wind River Fault. collected at the contact between the Wilkins Peak and Deformation of Reds Cabin Monocline postdates depo- Laney members (MacGinitie, 1969; Wolfe, 1978; Wilf, sition of the Cathedral Bluffs Tongue. The abrupt in- 2000). In the most recent reinvestigation of the paleo- crease in maximum grain size from pebbles to boulders, botanical record, Wilf (2000) showed that the MAT and a shift from rounded to angular clasts across the increased by 4 ºC, and the MAP decreased by 25 cm/ sequence boundary lends more support to the develop- yr between the Niland Tongue and upper Wilkins Peak ment of high relief near the Whitehorse Creek section. assemblages. This data suggests that the fluvial/allu- We propose that uplift of the Wind River Mountains vial Niland Tongue was deposited during a wetter pe- along the Continental Fault contributed to the diversion riod than the lacustrine upper Wilkins Peak and lower of rivers that had flowed into the greater Green River Laney members. This is inconsistent with the notion Basin during deposition of the Tipton Shale and Farson that large lakes form during wetter times, and contract Sandstone members. The result was a rapid decrease during climatically warmer-drier periods. Furthermore, in lake area and the ensuing deposition of evaporites and Surdam and Stanley (1980) correlated lacustrine strata associated underfilled lacustrine strata of the Wilkins between the greater Green River Basin and the Piceance Peak Member in the basin center, and alluvial deposi- Creek and Uinta basins to the south, based on strat- tion at the basin margin (Figure 8). 122

Figure 7. Oblique aerial photograph of the Whitehorse Creek section looking northwest towards the Wind River Mountains. Note the deltaic deposits of the Farson Sandstone Member overlain by an “exhumed” alluvial fan (Pacific Butte) of the Cathedral Bluffs Tongue that termi- nates along the trace of the Continental Fault.

Sandstone provenance provides further evidence of the Wind River Mountains (Figure 1). The streams for tectonic drainage reorganization. McGee (1983) supplying sand to the Farson Sandstone Member there- showed that sand grains in the Farson Sandstone Mem- fore must have crossed the present position of the Wind ber contain a heavy mineral assemblage similar to that River drainage divide. Furthermore, McGee (1983) of a iron formation exposed in the core interpreted variations in sandstone provenance between

Figure 8. Schematic illustration of Early Eocene uplift of the southern Wind River Mountains, and consequent river diversion and evolution from an overfilled to underfilled lacustrine basin. 123 beds within the Farson Sandstone Member to indicate Love Fellowship, and the Department of Geology and subtle shifts in source area caused by tectonic activity Geophysics at the University of Wisconsin-Madison. in the southern Wind River Mountains. Lacustrine sedimentary basin research at the Univer- sity of Wisconsin-Madison is also supported by a grant from the Donors of The Petroleum Research Fund, ad- Conclusions ministered by the American Chemical Society.

Structural and stratigraphic field relations across the greater Green River Basin provide a well-constrained References example of lacustrine evaporite deposition in response to a specific tectonic event. Because many lake basins Anderman G.G. 1955. Tertiary deformational history of a portion of are fundamentally associated with areas of active the north flank of the in the vicinity of Ma- orogenic uplift, the identification of long-term changes nila, Utah. Wyoming Geological Association Guidebook 10th in lacustrine facies associations offers an important Annual Field Conference. Wyoming Geological Society, Casper, pp. 130–134. (and under-utilized) means for helping to decipher up- Bell W.G. 1954. Stratigraphy and geologic history of Paleocene rocks lift histories. In addition, this study documents a pre- in the vicinity of Bison Basin, Wyoming. Geol. Soc. Am. Bull. viously unrecognized lacustrine sequence boundary 65 (Part II): 1371. from one of the most intensely studied lacustrine ba- Benson L.V. 1981. Paleoclimatic significance of lake-level fluctua- sins in the world. The use of sequence stratigraphy is tions in the Lahontan Basin. Quat. Res. 16: 390–403. Benson L.V. 1999. Records of millennial-scale climate change from widely accepted for marine basins, where stratal sur- the Great Basin of the western . In: Clark P.U., faces are formed by relative changes in sea level. Rela- Webb R.S. and Keigwin L.D. (eds), Mechanisms of Global tive sea level change encompasses eustatic sea level Climate Change at Millennial Time Scales. Geophys. Monogr. fluctuations, as well as regional and global tectonics. 112, pp. 203–225. Recent studies (e.g., Tang et al., 1994; Currie, 1997) Bouchard D.P., Kaufman D.S., Hochberg A. and Quade J. 1998. Quaternary history of the Thatcher Basin, Idaho, reconstructed have applied these same concepts to nonmarine basins form the 87Sr/86Sr and amino acid composition of lacustrine where sediment supply, regional tectonics, and local fossils: implications for the diversion of the Bear River into the climate control sequence development. Furthermore, Bonneville Basin. Palaeogeogr. Palaeoclimatol. Palaeoecol. Carroll and Bohacs (1999) argued that changes in lake- 141: 95–114. basin type, presumably marked by sequence strat- Bohacs K.M. 1998. Contrasting expressions of depositional se- quences in mudrocks from marine to non marine environs. In: igraphic surfaces, results from the balance between Schieber J., Zimmerle W. and Sethi P. (eds), Shales and Mud- tectonically controlled potential accommodation and stones I, Characteristics at the Basin Scale. Schweizerbart’sche the water+sediment fill rate commonly controlled by Verlagsbuchhandlung, Stuttgart, pp. 33–78. climate. However, episodic events such as faulting Bohacs K.M., Carroll A.R., Nede J.E. and Mankirowicz P.J. 2000. (described in this paper), catastrophic failure of basin Lake-basin type, source potential, and hydrocarbon character: an integrated sequence-stratigraphic-geochemical framework. sills (e.g., Malde, 1960; Stearns, 1962), or the diver- In: Gierlowski-Kordesch E.H. and Kelts K.R. (eds), Lake Ba- sion of rivers by volcanic flows (e.g., Bouchard et al., sins Through Space and Time. American Association of Petro- 1998) can alter the sediment + water fill rate. Collec- leum Geologists Studies in Geology #46, pp. 3–33. tively, these observations demonstrate the need for Bradley W.H. 1959. Revision of stratigraphic nomenclature of Green considerable caution when interpreting paleoclimatic River Formation of Wyoming. Am. Assoc. Petrol. Geol. Bull. 43: 1072–1075. change from lacustrine sedimentary facies evidence Bradley W.H. and Eugster H.P. 1969. Geochemistry and paleo- alone. limnology of the trona deposits and associated authigenic min- erals of the Green River Formation of Wyoming. United States Geological Society Professional Paper 496B, 71 pp. Acknowledgements Carroll A.R. and Bohacs K.M. 1999. Stratigraphic classification of ancient lakes: balancing tectonic and climatic controls. Geol- ogy 27: 99–102. We thank Reuben Johnson, Kevin Bohacs, Jack Neal, Culbertson W.C. 1969. Oil shale in the Green River Formation, Green John Guthrie, and Mike Smith for stimulating discus- River Basin, Wyoming. In: Barlow J.A. Jr. (ed.), Wyoming Geo- sions on the rocks. Joseph Smoot and Lluís Cabrera logical Association Guidebook, 21st Annual Field Conference. provided insightful reviews of the original manuscript. Wyoming Geological Society, Casper, pp. 191–195. Currie B.S. 1997. Sequence stratigraphy of nonmarine - This study was funded by donations from Conoco, Tex- Cretaceous rocks, central Cordilleran foreland-basin system. aco, the AAPG Grants-in-aid program, the J. David Geol. Soc. Am. Bull. 109: 1206–1222. 124

DeCelles P.G. 1994. Late Cretaceous-Paleocene synorogenic sedi- Mitchum R.M. Jr., Vail P.R. and Thompson S. 1977. Seismic strat- mentation and kinematic history of the Sevier thrust belt, north- igraphy and global changes of sea level, Part 2: The depositional east Utah and southwest Wyoming. Geol. Soc. Am. Bull. 106: sequence as a basic unit for stratigraphic analysis. In: Payton 32–56. C.E. (ed.), Seismic Stratigraphy-applications to Hydrocarbon Dorr J.A., Spearing D.R. and Steidtmann J.R. 1977. Deformation Exploration. American Association of Petroleum Geologists and deposition between a foreland uplift and an impinging Memoir 26, pp. 53–62. thrust belt: Hoback Basin, Wyoming. Geological Society of Olsen P.E. 1986. A 40-million- lake record of early Mesozoic America Special Paper 177, 82 pp. orbital climatic Forcing. Science 234: 842–848. Gómez-Fernández J.C. and Meléndez N. 1994. Climatic control on Oviatt C.G. 1997. Lake Bonneville fluctuations and global climate Lower Cretaceous sedimentation in a playa-lake system of a change. Geology 25: 155–158. tectonically active basin (Huérteles Alloformation, Eastern Owen R.B., Crossley R, Johnson T.C., Tweddle D., Kornfield I., Cameros Basin, North-Central Spain). J. Paleolim. 11: 91–107. Davison S., Eccles D.H. and Engstrom D.E. 1990. Major low Gries R. 1983. North-south compression of Rocky Mountain levels of Lake Malawi and implications for speciation rates in foreland structures. In: Lowell J.D. (ed.), Rocky Mountain cichlid fishes. Proceedings of the Royal Society of London, Foreland Basins and Uplifts, Guidebook. Rocky Mountain Series B, Biological Sciences 240: 519–553. Association of Geologists, Denver, pp. 9–32. Pietras J.T., Carroll A.R. and Rhodes M.R. 2000. Lacustrine Se- Hanley J.H. 1976. Paleosynecology of nonmarine Mollusca from the quence Stratigraphy: Example from the Green River Formation Green River and Wasatch formations (Eocene), southwestern of Southwestern Wyoming. Am. Assoc. Petrol. Geol. Annual Wyoming and northwestern . In: Scott R.W. and West Meeting (abstr), pp. A116. R.R. (eds), Structure and Classification of Paleocommunities. Roehler H.W. 1991. Revised Stratigraphic nomenclature for the Dowden, Hutchinson & Ross, Stroudsburg, pp. 235–261. Wasatch and Green River formations of Eocene age, Wyoming, Hayden F.V. 1869. Preliminary field report of the United States Utah, and Colorado. United States Geological Survey Profes- Geological Survey of Colorado and New Mexico. Government sional Paper 1506B, 38 pp. Printing Office, Washington, 155 pp. Roehler H.W. 1992a. Description and correlation of Eocene rocks Keefer W.R. 1965. Stratigraphy and geological history of the upper- in stratigraphic reference sections for the Green River and most Cretaceous, Paleocene and lower Eocene rocks on the Washakie basins, southwest Wyoming. United States Geologi- Wind River Basin, Wyoming. United States Geological Survey cal Survey Professional Paper 1506D, 83 pp. Professional Paper 495A, 77 pp. Roehler H.W. 1992b. Correlation, composition, areal distribution, Kowalewska A. and Cohen A.S. 1998. Reconstruction of paleo- and thickness of Eocene stratigraphic units, Greater Green environments of the Great Salt Lake Basin during the late River Basin, Wyoming, Utah, and Colorado. United States Geo- Cenozoic. J. Paleolim. 20: 381–407. logical Survey Professional Paper 1506E, 49 pp. Langbein W.B. 1961. Salinity and hydrology of closed lakes. United Roehler H.W. 1993. Eocene climates, depositional environments, States Geological Survey Professional Paper 412, 20 pp. and geography, Greater Green River Basin, Wyoming, Utah, Love J.D. 1954. Periods of folding and faulting during Late Creta- and Colorado. United States Geological Survey Professional ceous and Tertiary time. Am. Assoc. Petrol. Geol. Bull. (abstr) Paper 1506F, 74 pp. 38: 1311–1312. Sáez A., Cabrera L., Jensen A. and Chong G. 1999. Late Neogene Love J.D. 1970. Cenozoic geology of the Granite Mountains area, lacustrine record and Palaeogeography in the Quillagua- central Wyoming. United State Geological Survey Professional Llamara basin, Central Andean fore-arc (northern Chile). Paper 495C, 154 pp. Palaeogeogr. Palaeoclimatol. Palaeoecol. 151: 5–37. MacGinitie H.D. 1969. The Eocene Green River flora of northwest- Smith M.E. 2002. 40Ar/39Ar geochronology of the Eocene Green ern Colorado and northeastern Utah. University of California River Formation, Wyoming and Utah. MSc thesis, University Publication in Geological Sciences 83, 140 pp. of Wisconsin-Madison, Madison, 71 pp. Mallory W.W. 1972. Geologic Atlas of the Rocky Mountain Region. Smoot J.P. 1983. Depositional subenvironments in an arid closed Rocky Mountain Association of Geologists, Denver, 331 pp. basin; Wilkins Peak Member of the Green River Formation Malde H.E. 1960. Evidence in the Snake River plain, Idaho, of a (Eocene), Wyoming, U.S.A.. Sedimentology 30: 801–827. catastrophic flood from Pleistocene Lake Bonneville. United Stearns H.T. 1962. Evidence of Lake Bonneville Flood along Snake States Geological Survey Professional Paper 400B, pp. 295– River below King Hill, Idaho. Geol. Soc. Am. Bull. 73: 385– 297. 388. Markwick P.J. 1994. ‘Equability,’ continentality, and Tertiary ‘cli- Steidtmann J.R., McGee L.C. and Middleton L.T. 1983. Laramide mate’: the crocodilian perspective. Geology 22: 613–616. sedimentation, folding, and faulting in the southern Wind River Mauger R.L. 1977. K-Ar ages of biotites from tuffs in Eocene rocks Range, Wyoming. In: Lowell J.D. (ed.), Rocky Mountain Fore- of the Green River, Washakie, and Uinta basins, Utah, Wyo- land Basins and Uplifts, Guidebook. Rocky Mountain Associa- ming, and Colorado. Contributions to Geology, University of tion of Geologists, Denver, pp. 161–167. Wyoming 15: 17–41. Steidtmann J.R. and Middleton L.T. 1991. Fault chronology and May G. Hartley A.J., Stuart F.M. and Chong G. 1999. Tectonic sig- uplift history of the southern Wind River Range, Wyoming: natures in arid continental basins: an example from the Upper implications for Laramide and post-Laramide deformation in Miocene-Pleistocene, Calama Basin, Andean forearc, northern the Rocky Mountain foreland. Geol. Soc. Am. Bull. 103: 472– Chile. Palaeogeogr. Palaeoclimatol. Palaeoecol. 151: 55–77. 485. McGee L.C. 1983. Laramide sedimentation, folding and faulting Surdam R.C. and Stanley K.O. 1979. Lacustrine sedimentation dur- southern Wind River Range, Wyoming. PhD Diss., University ing the culminating phase of Eocene Lake Gosiute, Wyoming of Wyoming, Laramie, 92 pp. (Green River Formation). Geol. Soc. Am. Bull. 90: 93–110. 125

Surdam R.C. and Stanley K.O. 1980. Effects of changes in drainage- Using leaves as paleoprecipitation indicators: an Eocene basin boundaries on sedimentation in Eocene Lakes Gosiute and example. Geology 26: 203–206. Uinta of Wyoming, Utah, and Colorado. Geology 8: 135–139. Wilf P. 2000. Late Paleocene-Early Eocene climate changes in south- Tang Z., Parnell J. and Ruffell A.H. 1994. Deposition and diagenesis western Wyoming: Paleobotanical analysis. Geol. Soc. Am. of the lacustrine-fluvial Cangfanggou Group (uppermost Bull. 112: 292–307. to Lower ), southern Junggar Basin, NW Wing S.L. and Greenwood D.R. 1993. Fossils and fossil climate: the China: a contribution from sequence stratigraphy. J. Paleolim. case for equable continental interiors in the Eocene. R. Soc. 11: 67–90. Lond. Phil. Trans. 341: 243–252. Van Wagoner J.C., Posamentier H.W., Mitchum R.M. Jr., Vail P.R., Wolfe J.A. 1978. A paleobotanical interpretation of Tertiary climates Sarg J.F., Loutit T.S. and Hardenbol J. 1988. An overview of in the Northern Hemisphere. Am. Sci. 66: 694–703. the fundamentals of sequence stratigraphy and key definitions. Zachos J., Pagani M., Sloan L., Thomas E. and Billups K. 2001. In: Wilgus C.K, Hastings B.S., Ross C.A., Posamentier H.W., Trends, rhythms, and aberrations in global climate 65 Ma to Van Wagoner J.C. and Kendall C.G. (eds), Sea-level Changes; present. Science 292: 686–693. An Integrated Approach. Soc. Econ. Paleontol. Mineral. Spe- Zeller H.D. and Stephens E.V. 1969. Geology of the Oregon Buttes cial Publication 42, pp. 39–45. area, Sweetwater, Sublette, and Fremont counties, southwest- Wilf P., Wing S.L., Greenwood D.R. and Greenwood C.L. 1998. ern Wyoming. US Geol. Surv. Bull. 1256: 60. 126