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Facies architecture and sequence stratigraphy of the Park City Fm. , Utah and Wyoming: Implications for the Permian sea-level history of Pangea's western continental margin

Conference · · Geological Society of America, Abstracts with Programs; (United States)
OSTI ID:5767658
 [1]
  1. Syracuse Univ., NY (United States). Dept. of Geology

Carbonates of the Park City Fm. were particularly sensitive to changes in sea-level and climate and record progressively lower third-order sea-level highstands. These facies were deposited as transgressive, highstand, and initial lowstand systems tracts. Prior to deposition of the Park City Fm. eolian and shallow marine clastic sediments covered the Utah/Wyoming continental margin. A late Leonaridan third order sea-level highstand permitted progradation of a mixed carbonate-siliciclastic platform over the shelf. A subsequent third order sea-level lowstand exposed the eastern portion of the shelf forming a platformal unconformity and the base of the second depositional sequence. Carbonate conglomerates were deposited along the shelf margin and upper slope and clastic sediments once again were deposited on the shelf. During initial transgression bottom water anoxia and high surface productivity, induced by meridional upwelling, prevented benthic carbonate production. A condensed section consisting of reworked and phosphatized sands, pelletal and nodular phosphorite, and organic-rich shales was deposited. With continued transgression and the re-initiation of normal marine circulation carbonate production resumed and a second cycle of carbonate platform progradation ensued atop the Utah/Wyoming shelf. During the next third order sea-level lowstand the third sequence boundary was created as the platform was exposed to subaerial erosion. Carbonate conglomerates were once again deposited as a lowstand wedge and clastic sediments prograded across the shelf. Subsequent transgression caused the onlap of restricted basinal and high productivity facies in Wyoming and southwestern Montana producing a marine flooding surface and condensed section. Further transgression re-initiated carbonate production over the Utah/Wyoming shelf but Utah facies indicate shallow water, restricted marine conditions.

OSTI ID:
5767658
Report Number(s):
CONF-921058--
Journal Information:
Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
Country of Publication:
United States
Language:
English