Terminal Infill of Eocene Lake Gosiute, Wyoming

The composition and architecture of the clastic sediments preserved in Laramide basins provides a powerful record of erosion within the drainage basin as well as regional transport of surface waters. A new high-resolution stratigraphic model for the Laney Member of the Green River Formation and laterally equivalent clastic sediments in the Greater Green River Basin (GGRB) illustrates the dynamic nature of this regional drainage system. The base of the Laney Member corresponds to the transition from a hydrologically isolated basin, to a basin that was periodically connected to the regional drainage system. The new correlation demonstrates that during the Laney interval, the Rock Springs Arch (RSA) partitioned the GGRB into eastern and western sub-basins. During Wilkins Peak to earliest Laney time, the dominant drainage entered the basin from the east, resulting in westward transport and deposition of arkosic alluvial detritus. In contrast, during Laney deposition the polarity of drainage across the RSA reversed, and volcaniclastic sediments derived from northwest were progressively deposited southward and eastward across the GGRB. This reversal in the polarity of drainage across the GGRB signals the reintegration of Lake Gosiute back into a regional network following a prolonged period of hydrologic and sedimentologic isolation. The long-term geomorphic evolution of the surrounding orogenic landscape thus exerted a primary control on the character of nonmarine basin fill.