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Studies of the Permian Phosphoria Formation and related rocks, Great Basin-Rocky Mountain region

January 1, 1979

PART A: The transgression of the Permian Retort Phosphatic Shale Member of the Phosphoria Formation is dated by the occurrence of diagnostic brachiopods. The complex pattern of this transgression reflects the paleogeography and indicates two initial basins of deposition: one in southwestern Montana and one in southeastern Idaho.

PART B: A new formation is proposed for middle Permian rocks of a transitional facies positioned laterally between the Rex Chert Member of the Phosphoria Formation in northeastern Utah and southeastern Idaho and the Plympton Formation in northeastern Nevada and northwestern Utah.

PART C: The relationships of the Permian Park City Group to the Phosphoria and Park City Formations are clarified by the stratigraphy of four sections in northwestern Utah, northeastern Nevada, and southern Idaho.

PART D: Five biostratigraphic zones based on the distribution of brachiopods and conodonts are proposed for the Park City Group. They are: the Peniculauris ivesi-Neostreptognathodus prayi Zone, the Peniculauris bassi-Neostreptognathodus sulcoplicatus Zone, the Peniculauris bassi-Neostreptognathodus sp. C Zone, the Thamnosia depressa Zone, and the Yakovlevia. multistriata-Neogondolella bitteri Zone. They range in age from Leonardian to Wordian.

Publication Year 1979
Title Studies of the Permian Phosphoria Formation and related rocks, Great Basin-Rocky Mountain region
DOI 10.3133/pp1163AD
Authors Bruce R. Wardlaw
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Professional Paper
Series Number 1163
Index ID pp1163AD
Record Source USGS Publications Warehouse
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