Playa-lake and clastic deposition in Paleocene-Eocene Flagstaff limestone, Wasatch Plateau, Utah
Abstract (Summary)The Paleocene-Eocene Flagstaff Limestone is sub¬divided into lower, middle, and upper members on the basis of faunal, petrographic, and sedimentary features. The Lower and Upper Members were deposited in a freshwater lake, whereas the Middle Member represents a playa-lake complex. The Middle Member, 169.1 m thick, is character¬ized by (1) 13 m bedded gypsum; (2) evaporite mineral molds in dolomicrite; (3) presence of euryhaline ostracodes and absence of freshwater mollusks; (4) mudcracked horizons; (5) exclusive dolomite lithology; (6) thinly bedded dolo¬micrite with laminated to massive intraclastic textures; and (7) red bed intervals. A regional increase in aridity induced development of the complex. Dolomicrite, which was formed penecontemporaneously in carbonate-rich mudflats adjacent to the lake by evaporative pumping of groundwater, was carried as intraclasts by sheetwash flooding into a central saline lake.Terrigenous material was supplied from eastern and western sources. Lithic arenite and subfeldspathic lithic arenite, derived from Mesozoic sedimentary rocks of the San Rafael Swell to the east, were deposited as sheets on the playa surface and in meandering to braided stream channels on the floodplain. Subfeldspathic lithic arenite derived from Cretaceous and older sedimentary rocks of the Sanpete Valley anticline to the west, represent beach sediment de¬posited along a local high.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/1977