UGA 50:04 - Paleoenvironmental Reconstructions Along the Southern Margin of Eocene Lake Uinta During a Period of Climatic Variability: The Middle to Upper Green River Formation, Uinta Basin, Utah Off-Canvas Toggle Member Login Donate About Publications Geology of the Intermountain West Guidebooks UGA Geosites Special Publications UGA 28 Topical Papers Members Member Benefits Become a Member Resources Newsletter Meeting Minutes Geologic Road Signs Geology Links UGA Constitution Outreach Student Scholarship Fund Teacher of the Year Become a Sponsor UGA Sponsors & Affiliates Lehi Hintze Award Events Contact UGF About UGF Donate to UGF Off-Canvas Toggle About Publications Geology of the Intermountain West Guidebooks UGA Geosites Special Publications UGA 28 Topical Papers Members Member Benefits Become a Member Resources Newsletter Meeting Minutes Geologic Road Signs Geology Links UGA Constitution Outreach Student Scholarship Fund Teacher of the Year Become a Sponsor UGA Sponsors & Affiliates Lehi Hintze Award Events Contact UGF About UGF Donate to UGF Off-Canvas Toggle thisistheplace2.jpeg subpage1.jpeg subpage2.jpeg subpage3.jpeg UGA 50:04 - Paleoenvironmental Reconstructions Along the Southern Margin of Eocene Lake Uinta During a Period of Climatic Variability: The Middle to Upper Green River Formation, Uinta Basin, Utah Lauren P. Birgenheier - University of Utah, Department of Geology and Geophysics Leah C. Toms - Beach Energy DOI: https://doi.org/10.31711/ugap.v50i.108 Abstract The stratigraphy preserved in the lacustrine Eocene Green River Formation suggests a variety of depositional environments that were subject to pulses of sediment and lake level fluctuations in the Uinta Basin. This paper defines 13 facies within six facies associations observed in outcrop and core from the middle to upper Green River Formation in Gate Canyon, south-central Uinta Basin, and Willow Creek/Indian Canyon, western  Uinta Basin, along the margin of the ancient lake system. The facies associations are defined by dominant lithology, relative siliciclastic sediment supply, relative slope, and lake zonation, and encompass a suite of facies revealing distinct environments across a relatively small region (~35 km apart). In the lower interval, a shift  from a high energy, steeper ramp setting in the east, to a lower energy, shallower ramp setting to the west suggests a transition off the main depositional axis. Correlatable siliciclastic and carbonate dominated packages  reflect the impact of early Eocene hyperthermal events that followed the Paleocene-Eocene Thermal Maxi- mum, and the diverse facies present at the two study areas suggest variable responses to these climatic events.  In the overlying stratigraphy, the facies are consistent in both regions and consist of organic rich and poor carbonate mudstones and siltstones. The interval thickens slightly from east to west, and the overlying Horse  Bench Sandstone transitions from a wave-dominated shoreface sequence to a river-dominated deltaic sequence, indicating an overall shift in the lake depocenter towards the west. This study offers a unique glimpse  at the paleoenvironmental changes along the margin of a continental interior lake system during a time of climatic variability. It also highlights the need to use multiple depositional models to accurately characterize marginal deposits in different regions of large internally-drained lake systems which, unlike typical marine depositional models, are more sensitive to basin geometry, size, and sediment fairways. Order It ($5.00) Cart Your cart is empty Login Form Login for discounted rates on document downloads and to access members only content Username Password Show Password Remember Me Log in Forgot your password? Forgot your username? Create an account Utah Geological Association P.O. Box 526356 Salt Lake City, UT 84152-0100  Facebook  YouTube © 2025 Utah Geological Society | Site by Third Sun MEMBER LOGIN Off-Canvas Toggle About Publications Geology of the Intermountain West Guidebooks UGA Geosites Special Publications UGA 28 Topical Papers Members Member Benefits Become a Member Resources Newsletter Meeting Minutes Geologic Road Signs Geology Links UGA Constitution Outreach Student Scholarship Fund Teacher of the Year Become a Sponsor UGA Sponsors & Affiliates Lehi Hintze Award Events Contact UGF About UGF Donate to UGF