Stratigraphic Expression of Climate, Tectonism, and Geomorphic Forcing in an Underfilled Lake Basin: Wilkins Peak Member of the Green River Formation

摘要: The Wilkins Peak Member of the Green River Formation is a complex amalgam lacustrine and alluvial lithofacies deposited in closed basin at center Laramide broken foreland during Early Eocene (51.6–49.8 Ma). Facies analysis correlation surface sections core document remarkable lateral continuity depositional cycles within Member. New mapping facies this stratigraphic framework into Member-equivalent strata adjacent to Uinta Uplift, where peripheral belt contains fluvial that are compositionally distinct from interior facies. Peripheral composed limestone quartzose siliciclastic detritus, whereas largely dolomite fine-grained arkosic detritus. Strata both belts clear oscillation between two modes: (1) mode, associated with rapid lake expansion contraction precipitation carbonate evaporites saline waters; (2) an low level lower salinity basin-ward shift environments. Radioisotopic geochronology suggests lacustrine-alluvial strongly follow 100 k.y. eccentricity, modes occurring eccentricity maxima, coinciding minima. Alluvial fans were built Bridger subbasin over 2–4 million year timescales, their coarsest-grained portions corresponding unroofing durable Paleozoic Uplift. From 56 47 Ma, successive propagated westward as expanded away structural culmination Calcite-rich including spring deposits concentrated near faults fan toes, likely promoted by mixing Ca-rich meteoric and/or hydrothermal waters bicarbonate-rich waters. Accounting for absence interior-focused Tipton Formation, tectonic accommodation appears have been continuous rather than episodic late Paleocene Eocene.