Uinta Formation Research Articles

Hindlimb adaptations in Ourayia and Chipetaia, relatively large‐bodied omomyine primates from the Middle Eocene of Utah

North American omomyids represent a tremendous Eocene radiation of primates exhibiting a wide range of body sizes and dietary patterns. Despite this adaptive diversity, relatively little is known of the postcranial specializations of the group. Here we describe hindlimb and foot bones of Ourayia uintensis and Chipetaia lamporea that were recovered from the Uinta B member (early Uintan Land Mammal Age), Uinta Formation, Utah. These specimens provide insights into the evolution of postcranial adaptations across different body sizes and dietary guilds within the Eocene primate radiation. Body mass estimates based on talar measurements indicate that Ourayia uintensis and Chipetaia lamporea weighed about 1,500-2,000 g and 500-700 g, respectively. Skeletal elements recovered for Ourayia include the talus, navicular, entocuneiform, first metatarsal, and proximal tibia; bones of Chipetaia include the talus, navicular, entocuneiform, and proximal femur. Both genera had opposable grasping big toes, as indicated by the saddle-shaped joint between the entocuneiform and first metatarsal. Both taxa were arboreal leapers, as indicated by a consistent assemblage of characters in all represented bones, most notably the somewhat elongated naviculars, the high and distinct trochlear crests of the talus, the posteriorly oriented tibial plateau (Ourayia), and the cylindrical head of the femur (Chipetaia). The closest resemblances to Ourayia and Chipetaia are found among the Bridger omomyines, Omomys and Hemiacodon. The results of our comparisons suggest that the later, larger, more herbivorous omomyines from Utah retained a skeletal structure characteristic of earlier, smaller North American omomyids.

The rodentMytonomysfrom the Uintan and Duchesnean (Eocene) of Utah, and the content of the Ailuravinae (Ischyromyidae, Rodentia)

The Uintan Leptotomus mytonensis Wood is transferred to the genus Mytonomys Wood, and the Duchesnean Leptotomus kayi Burke is synonymized with M. robustus (Peterson). Thus, two species of Mytonomys...

Petroleum Geology of Greater Altamont Area, Uinta Basin, Utah: ABSTRACT

The Greater Altamont area consists of a group of major, naturally fractured, overpressured petroleum reservoirs situated on the gently northward-dipping flank of the asymmetric Uinta basin. This area produces approximately 17,000 BOPD and 29 MMCFGD--one-half the petroleum production in the Uinta basin. It presently consists of three contiguously producing designated fields: Altamont, Bluebell, and Cedar Rim. The Tertiary Uinta, Green River, Wasatch, and North Horn Formations and the Tertiary-Cretaceous Flagstaff Limestone are the source and reservoir rocks. The low-porosity sandstones and siltstones form the stratigraphic traps within the interbedded shales. Vertical fractures provide the necessary permeability in these formations. Producing intervals occur at depths between 3,700 and 18,613 ft (1,128 and 5,673 m), each with an average thickness of 311 ft (95 m). Average recovery is expected to be approximately 12%. Completion techniques play an important role in the primary production of oil from the area. Several extraction methods used in the area have resulted in variation of longevity of the wells. Secondary recovery is not deemed feasible owing to the type of reservoir; repressuring would result in channeling along fractures, bypassing most of the oil in place. In the near future, the Greater Altamont area is envisaged to extend farther south, as indicated by Sonat's recently completed producing wells in T3S, R1-2W. End_of_Article - Last_Page 935------------

Regional Stratigraphic and Depositional Study of Rock Units in Upper Garden Gulch and Parachute Creek Members of Green River Formation, Piceance Creek Basin, Colorado: ABSTRACT

The Eocene Green River Formation in the Piceance Creek basin, Colorado, is well known for its thick sequence of rich oil shale and associated saline minerals. In the subsurface, rocks of economic interest extend from the upper part of the Garden Gulch Member to the top of the Parachute Creek Member. These rocks are lacustrine deposits that represent open-and near-shore sedimentation in ancient Lake Uinta. The depocenter of the lake formed in the northern part of the basin where rates of subsidence exceeded rates of sedimentation. The Garden Gulch and Parachute Creek Members can be divided into a series of laterally gradational rock units that can be traced from the eastern part of the Piceance Creek basin westward into the south-central part of the Uinta basin, Utah. Alon the margins of the Piceance Creek basin, the lower and middle units consist of fissile argillaceous shale of low organic content, silty claystone, and siltstone. Toward the depositional center of the basin, these rocks grade into a thick sequence of carbonate-rich, kerogenous shale and lean marlstone that is interbedded with a saline facies composed of nahcolite, dawsonite, and halite. The gradational boundary between these facies represents the contact between the Garden Gulch and Parachute Creek Members. In the subsurface, the contact can be recognized by a change from a low to high resistivity log response which reflects the transition from clay-rich to carbonate-rich rock. The regional thickness distribution pattern of individual units suggest that, during the middle Eocene, Lake Ui ta gradually expanded from a shallow, relatively fresh, semirestricted body of water to a saline, alkaline lake that occupied a closed basin. A pronounced thickening of the lowermost units along the southern margin of the basin is attributed to streams that prograded northward into the basin from the southern and southwestern margin of the lake. The middle and upper units, however, thin toward the basin edge, suggesting the lake gradually expanded to the south. During the late Eocene, open-lacustrine sedimentation shifted from the Piceance Creek basin westward into the Uinta basin, Utah, due to a large influx of siliciclastic sediment (Uinta Formation). Structural analysis of individual units indicates that present day intrabasinal tectonic features were not in existence during Parachute Creek time. End_of_Article - Last_Page 535------------

Characteristics of Some Oil Shale, East-Central Uinta Basin, Utah: ABSTRACT

Oil-yield, lithologic, and mineral-distribution data were determined for cores taken from a 152-m drill hole in the upper part of the Parachute Creek Member of the Eocene Green River Formation. The drill hole, in Sec. 3, T12S, R24E, started just below the contact between the Uinta Formation and the underlying Green River Formation, and ended 10 m below the Mahogany oil shale bed (the richest oil shale bed in the interval examined) in the lower part of the Mahogany zone. Most of the interval studied is composed of kerogen- and carbonate-rich, very fine-grained sediments. Several thin (less than 1 m) oil shale beds which yield as much as 25 gal of oil per ton (104.3 l per metric ton) are above the Mahogany zone, but are probably not of economic interest. The studied sequence contains several tuff beds; the maximum thickness of these beds is about 0.6 m, but the average thickness rarely exceeds 0.2 m. Two oil-saturated tuff beds occur approximately 20 m above the Mahogany oil-shale bed. Although these two tuffs are exposed in nearby surface outcrops, they do not contain oil in these outcrops. The Mahogany zone is approximately 21 m thick at the drill site; the lowermost few feet were not penetrated. The Mahogany zone is covered by 132.6 m of overburden. Fischer assays indicate that 12.9 m of oil shale within the Mahogany zone could yield at least 25 gal of oil per ton (104.3 l per metric tone) from beds at least 3 m thick. Although analcime is a common accessory mineral in the upper 50 m of the core hole, it was not identified in the Mahogany zone. Illite and mixed-layer clay minerals occur together above the Mahogany zone. The mixed-layer clays decrease in quantity as the Mahogany zone is approached, and no mixed-layer clays are detected in the Mahogany zone. Illite was detected in all samples examined from the Mahogany zone. Examination of X-ray diffraction patterns obtained from bulk rock samples from cores did not reveal the presence of any potentially valuable accessory minerals in the stratigraphic interval studied. End_of_Article - Last_Page 944------------

Tertiary Correlations in Bighorn and Uinta Basins, Wyoming and Utah: ABSTRACT

Electrical accessory curves have been used to map the Mesaverde, Lance-Meeteetse, Fort Union, and Willwood Formations in the Bighorn basin of Wyoming. These subsurface mapping units have been correlated to mapped outcrops on the flank of the basin. Recent authors have concluded that the basin started to subside during upper Lance deposition; however, I conclude that most subsidence along the axis of the basin was in late Paleocene and Eocene times (upper Fort Union and Willwood). Electrical accessory curves also were used to map the Mesaverde, Wasatch, Green River, Uinta, and Duchesne River Formations in the Uinta basin of Utah. These subsurface formations have been correlated to mapped outcrops on the south flank of the basin. Thickening of the Uinta and Duchesne River Formations into the basin indicates that the main subsidence along the axis of the basin was in late Eocene time. End_of_Article - Last_Page 825------------

Rodents of the Swift Current Creek local fauna (Eocene: Uintan) of Saskatchewan

The ischyromyid rodents Reithroparamys sp., Ischyrotomus cf. I. compressidens, and Is-chyrotomus cf. I. eugenei are present in the Swift Current Creek local fauna (Eocene: Uintan), Cypress Hills Formation of Saskatchewan. Co-occurrence of these taxa strengthens correlation with the fauna of the Myton Member, Uinta Formation of Utah.

Volcanic Sandstone in Green River and Uinta Formations, Uinta Basin, Utah: ABSTRACT

Volcanic Sandstone in Green River and Uinta Formations, Uinta Basin, Utah: ABSTRACT

Paleocurrent Analysis and Orientation of Sandstone Bodies in the Duchesne River Formation (Eocene-Oligocene?), Northern Uinta Basin, Northeastern Utah

Paleocurrent reconstruction, based on measurements of medium-scale trough cross-stratification, indicates generally southward flow directions throughout the northern Uinta Basin during Duchesnean time. In contrast, measurements from the Upper Myton Member of the Uinta Formation indicate that streams flowed westward across the Uinta Basin during late Uintan time.

Tectonics and Depositional History of Rocky Mountain Intermontane Basin: ABSTRACT

In the Uinta basin of northeastern Utah, the Uinta and Duchesne River Formations are composed of extremely diverse fluvial sedimentary rocks. The rock units overlie extensive lacustrine deposits of Lake Uinta and provide a sensitive record of late Laramide (latest Eocene) tectonic events in this part of the Rocky Mountains. The fluvial deposits are dominantly heterogeneous, laterally discontinuous sandstone lenses and varied amounts of conglomerate and poorly stratified, fine-grained rocks. Uplift of the Uinta Mountains changed geographic conditions and drainage patterns in the Uinta basin and strongly influenced the characteristics of contemporaneous sedimentary deposits. Important features of the stratigraphic sequence are (1) the oldest major body of sediment (early Duchesnean) produced during uplift of the Uinta Mountains is considerably younger than the youngest preserved deposits of Lake Uinta (middle Uintan); (2) lower (early Duchesnean) and upper (late Duchesnean) conglomeratic rock units record two major episodes of uplift, each composed of several smaller events; and (3) thick volcanic ash deposits, now altered, accumulated during the quiescent period (middle Duchesnean) between major uplifts. This sequence of events imposes some constraints on inferred geomorp ic development of the region. The deposits also demonstrate that the latest Eocene (about 40 m.y. ago) was a time of major differential movement of the Uinta Mountains and the Uinta basin, and was not a time of tectonic quiescence in northeastern Utah. Because of the great distance of the Rocky Mountains from the North American continental margins, detailed knowledge of local tectonic timing affords the best opportunity for plausible speculations relating plate tectonic mechanisms to Laramide events and to early development of the Colorado Plateau and the Basin-Range province. End_of_Article - Last_Page 767------------

Upper Cretaceous-Lower Tertiary Relations West of Raven Ridge, Uintah County, Utah: NOTES

Field work indicates that the upper Mesaverde, Wasatch, Green River, and Uinta Formations are stratigraphically conformable. The lacustrine Green River sequence is interpreted to intertongue with and grade laterally into nonlacustrine strata of the Wasatch and Uinta Formations.

DURATION OF EOCENE LAKE, UINTA BASIN, UTAH

From accumulation rates, the writer estimates the duration of the Green River and lower Uinta formations (Eocene) lake in the Uinta basin, Utah, to be 13.3 m.y. In the Rocky Mountain region, predominant lacustrine conditions during Eocene time existed no longer than this.

Stratigraphic and Facies Relationships of Upper Part of Green River Formation and Lower Part of Uinta Formation in Duchesne, Uintah, and Wasatch Counties, Utah

The Parachute Creek member of the Green River formation is an approximately time-equivalent zone across the Uinta Basin of Utah, as shown by the correlation of extensive thin tuff beds within the member. The top of the overlying Evacuation Creek member is regarded as the base of the Uinta formation. This formation boundary rises stratigraphically toward the center of the basin, as also shown by the correlation of tuff beds. Much of the lower part of the fluviatile beds of the Uinta formation as exposed along the Colorado-Utah line grades westward into beds that are in considerable part of lacustrine, playa, and mud-flat origin in an area of which Indian Canyon is the center. These beds, formerly considered a saline facies of the Green River formation, are here included as part of the Uinta formation.

The Upper Uinta Formation of northeastern Utah

The Upper Uinta Formation of northeastern Utah

The fossil turtles of the Uinta formation

The fossil turtles of the Uinta formation

Geology of the Uinta formation

Introduction The deposits here discussed were called the “Uinta Group” by Clarence King in 1878. The great thickness of reddish sandstones and quartzites of the Paleozoic of the Uinta Mountains were previously, in 1878, named “Uinta” by Powell. It is best, therefore, at present to designate the deposits now under discussion as the “Uinta Group” or the “Uinta Tertiary.” The Uinta Tertiary has furnished many interesting mammalian and reptilian remains, and several expeditions have been sent into the Uinta Basin to collect fossils. Some of these show that at least part of these deposits are newer than the typical Bridger and older than the White River Oligocene; therefore the name of the group has given the name to a stage in the development of vertebrate life called the “Uinta stage.” The main area containing the Uinta Group is quite extensive, but lies in one compact body and the boundaries, as . . .

The Mammalia of the Uinta Formation

The Mammalia of the Uinta Formation