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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 1000

Last Page: 1000

Title: Sedimentologic Framework of Green River Formation, Wyoming: ABSTRACT

Author(s): Ronald C. Surdam, K. O. Stanley

Article Type: Meeting abstract


During deposition of the Green River Formation, ancient Lake Gosiute began as a freshwater lake, evolved to a saline, alkaline lake, and ended as a freshwater lake. This evolution reflects the change from a closed-basin to an open-basin hydrologic regime; as a result, sedimentation in the Lake Gosiute system was strongly influenced by the relation between evaporation and inflow of water into the basin. In the Green River Formation, stratification sequences, sedimentary structures, and mineralogy of lithofacies provide important insights into the evolution of the system and the competing factors that determined the type of sediment accumualated in the lake and fringing environments. Carbonate sedimentation was strongly influenced by lacustrine transgressions and regression across a low topographic gradient. Terrigenous rocks reflect progradation of beach and deltaic shorelines during wetter climatic intervals when detritus that was produced and stored in upland areas during preceding drier intervals was transported to the lake.

Hydrochemistry of lake Gosiute during the deposition of the Wilkins Peak member was controlled by ground water discharge; during the deposition of the Tipton and Laney Members it was controlled largely by surface water. Calcite precipitated as a result of mixing calcium-rich inflow and saline-alkaline lake waters. Dolomite formed as a result of periodic flooding and drying of the playa fringe (carbonate mud flat), where carbonate muds were saturated with saline-alkaline lake waters and underwent evaporitive pumping. Some surface waters were preconcentrated by dissolution of efflorescent crusts in alluvial plain and mud-flat sediments. Trona and halite precipitated from brine pools as the lake shrank during periods of intense aridity. During himid periods the lake expanded and oil shal was deposited.

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