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Book Chapter

Pennsylvanian Sedimentation in Paradox Basin, Four Corners Region1

By
Sherman A. Wengerd
Sherman A. Wengerd
Albuquerque, New Mexico
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Published:
January 01, 1962

Abstract

The Paradox basin, about 360 miles long in northwesterly trend, and 180 miles wide, subsided obliquely across the high southeast shelf of the Cordilleran geosyncline during mid-Pennsylvanian time after an earlier Pennsylvanian history of shelf deposition of red clastics to form the Molas formation, and gray marine shale and limestone to form the Pinkerton Trail formation. The early autogeosynclinal subsidence of this intracratonic parageosyncline allowed the deposition of the Paradox formation comprising major cyclic deposits of normal marine, penesaline, and saline strata, and simultaneous emplacement of medium-to coarse-grained clastics from the Uncompahgre-San Luis-Penasco highland on the northeast and east, and fine- to medium-grained clastics from the Zuni-Defiance-Kaibab-Emery positives on the south, southwest, west, and northwest. This restricted basin of evaporite deposition underwent rigorous aridity cyclically interspersed with what appear to have been humid conditions, while normal marine waters entered the basin episodically to cyclically through sedimentational passes or marine accessways from the Sonoran geosyncline on the south and the Cordilleran geosyncline on the west.

Increased tectonic intensity in late Pennsylvanian led to sharp subsidence of the northeast flank of the Paradox autogeosyncline, to form the Uncompahgre taphrogeosyncline, into which were dumped many cubic miles of coarse arkosic clastics from the sharply uplifted Uncompahgre highland. These clastics interfinger southwestward with normal marine shale and carbonates of the Honaker Trail formation, deposited as the basin became thoroughly ventilated via additional marine accessways across the shelves of the basin. High on the Paradox-Uncompahgre southwestern shelf, Coconino-type quartzose clastics and Supai-type fine clastics moved into the basin from westerly and southerly directions, which, combined with influx of Uncompahgre-San Luis-Penasco clastics from the northeast and east, drove the seas from the area during latest Pennsylvanian to early Permian time.

The interfingering of invading clastics, combined with the generation of organic deposits along a broad zone of the southwest sedimentational shelf parallel with the strike of the Paradox basinal axis where thick evaporites were formed, created the facies gradations that make the Paradox basin a classic area for the study of Pennsylvanian stratigraphic and sedimentologic complexities.

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Contents

AAPG Special Publication

Pennsylvanian System in the United States

Carl C. Branson
Carl C. Branson
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American Association of Petroleum Geologists
ISBN electronic:
9781629812373
Publication date:
January 01, 1962

GeoRef

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