Depositional History Of The Lower Permian Carolyn Formation And Poole Sandstone In The Northern Canning Basin

Author : Michael T. Whalen
Publisher :
ISBN 13 :
Total Pages : 540 pages
Book Rating : 4.:/5 (823 download)

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Download or read book Depositional and Diagenetic History of the Park City Formation (Permian) Carbonate Ramp, Northwestern USA written by Michael T. Whalen and published by . This book was released on 1993 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: A regional analysis of the mid-Permian Park City Formation has revealed insights into the paleogeography and sea-level history of Pangea's western continental margin. In northern Utah and western Wyoming the Park City carbonate-siliciclastic ramp interfingered with sabkha facies to the east and organic-rich, oxygen-deficient basinal facies to the west. Facies patterns indicate a distally steepened ramp in the south grading into a homoclinal ramp with intra-ramp basins in the north. The Park City Formation has undergone extensive diagenesis, including at least two phases of dolomitization. The Park City and intercalated Phosphoria Formation were deposited as three or possibly four depositional sequences. Sequences are characterized by shoaling-upward cycles that vary lithologically depending on their paleogeographic location. Available biostratigraphic data allow equivocal correlation of the Park City-Phosphoria deposition sequences with mid-Permian third-order eustatic sea-level fluctuations. Intra-sequence shoaling-upward cycles may indicate the effects of higher-order sea-level changes. Carbonate ramp termination was caused by increased clastic input and ultimately subaerial exposure during sea-level lowstand. Areally and volumetrically extensive carbonate platforms are conspicuously absent from most modern eastern ocean basins where surface circulation brings cool waters from high latitudes and atmospheric circulation produces coastal upwelling and high surface productivity. In contrast to modern patterns, Silurian to Permian carbonate platforms were extensive along the eastern boundary of the ancestral Pacific Ocean (western margin of North America). Tectonic and sedimentologic evidence suggests that outboard oceanographic barriers (island arcs or foreland fold-and-thrust belts) existed throughout this interval. These barriers effectively protected inboard carbonate platforms from the adverse conditions typical of open eastern ocean basins and allowed their development along the western margin of North America. In regions that lack evidence for structurally or tectonically controlled highlands, the very existence of eastern ocean basin carbonate platforms may serve as a vital clue to interpreting paleogeography. Regional Permian lithofacies patterns to the west of Park City-equivalent basinal facies indicate shallowing and a nearby sediment source. The Park City carbonate ramp was thus bordered to the west by a barred marginal basin. The transgression of toxic, oxygen-deficient, sulfidic water during sea-level rise temporarily prevented reinitiation of benthic carbonate production as a phosphatic condensed section formed. (Abstract shortened by UMI.).