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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 51 (1967)

Issue: 9. (September)

First Page: 1903

Last Page: 1903

Title: Mississippian and Pennsylvanian Stratigraphy in Middle and Southern Rocky Mountains: ABSTRACT

Author(s): William W. Mallory

Article Type: Meeting abstract

Abstract:

Kinderhook and Osage rocks record a marine advance from the northwest. The sea covered only part of Wyoming in Kinderhook time, but inundated nearly all of the region in Osage time. In Meramec time it retreated. Earlier deposited Mississippian rocks were widely eroded in late Meramec and early Chester times when the region was emergent. In the late Chester another advancing sea flooded a mature topography in Wyoming developed on the Madison Limestone.

Most Mississippian rocks in the region are carbonate, but traces of anhydrite in rocks of Meramec age in Wyoming suggest that evaporitic strata equivalent to the Charles Formation once were widespread. Sandstone and shale are present in the Humbug Formation (Meramec) and in the lower part (Chester) of the Manning Canyon Shale in northeastern Utah.

Pennsylvanian rocks display marked local diversity of extent, thickness, and lithology which contrasts with the high degree of lithologic homogeneity in Mississippian rocks. By Early Pennsylvanian time the marine waters which began their advance in the Chester covered most of Wyoming, but much of Colorado and eastern Utah was still emergent. In Des Moines time maximum marine transgression and maximum elevation of the Ancestral Rocky Mountains took place. Evaporites were deposited in basins adjacent to the mountains while coarse red clastic rocks accumulated near shorelines. On the Wyoming shelf widespread well-sorted Tensleep sands were deposited.

In Late Pennsylvanian time regression and shoaling of the sea limited the extent of marine deposition, and tectonic activity diminished.

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