--> Abstract: Pennsylvanian-Permian Foreland Tectonism, Western United States, by W. S. Snyder, C. Spinosa, D. M. Gallegos, and D. L. Schwarz; #91012 (1992).

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ABSTRACT: Pennsylvanian-Permian Foreland Tectonism, Western United States

SNYDER, WALTER S., C. SPINOSA, DORA M. GALLEGOS, and DAVID L. SCHWARZ, Boise State University, Boise, ID

Active tectonism characterized the foreland of the Antler orogenic belt during the Pennsylvanian-Permian. This tectonism, documented by regional and local uplifts, folding, tilting, and basin formation, post-dates the Antler orogeny, and apparently pre-dates the latest Permian-early Triassic Sonoma orogeny. A Morrowan through medial Desmoinesian "Oquirrh" tectonic phase is marked by the appearance of the Ely and Oquirrh basins and the continued development of the Prophet trough in Canada. The Late Pennsylvanian "Humboldt" phase tectonism is marked by localized but regionally extensive uplift and erosion. In the Canadian Cordillera, this tectonic unrest produced a major, sub-Permian unconformity that forms the boundary between the Carboniferous Prophet trough and the Early Permian sedi ents of the Ishbel trough. The "Dry Mountain" phase began in medial to late Wolfcampian time with the development of a series of sedimentary basins along the continental margin. The phase ended in medial Leonardian time when uplift and, at least locally, low intensity compressive deformation initiated the "Ishbel" phase. During the Dry Mountain phase, a series of deeper water basins and associated highs developed along the continental margin from the Mojave Desert region northward to the Yukon. Sedimentary basins developed during the Ishbel phase typically have an initial basal unconformity developed on folded and tilted subjacent strata. Recognition of these Pennsylvanian and Permian tectonic phases helps to clarify some aspects of the intraplate deformation associated with the Ouachita Marathon orogeny and the nature and age of the Sonoma orogeny.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)