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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 914

Last Page: 914

Title: Climatic and Structural Controls of Stacked Algal Lime Mud Mound Development in Oquirrh Group (Pennsylvanian and Permian), Deep Creek Mountains, Southeastern Idaho: ABSTRACT

Author(s): Leland D. Cress

Article Type: Meeting abstract


Oquirrh Group rocks comprise the uppermost of a series of allochthons exposed in southern Idaho. The basal unit of the Oquirrh Group, the West Canyon Limestone (Atokan), is composed largely of lime mudstone and fossiliferous lime wackestone with the exception of a coarse qaurtzarenite and lime mudstone clast debris flow that originated from syndepositional faulting. Overlying this unit are unnamed cyclic back-mound siltstones, sandstones, cherts, and fossiliferous wackestones and packstones that thicken southward from 270 to an estimated 1,000 m of noncyclic strata of similar lithologies. Cyclic, thinly stacked algal lime mud mounds are inferred to have developed in Desmoinesian time. In Virgilian time, syndepositional faulting controlled the development of thickly stacke (700 m) algal, lime-mud mounds. To the north and west, cyclic back-mound lithofacies consist of siltstone, sandstone, chert, lime mudstone, and fossiliferous wackestone and packstone. Similar but noncyclic fore-mound lithofacies are greatly thickened southward suggesting that syndepositional faulting controlled sedimentation.

In Wolfcampian time, cyclic, stacked bryozoan algal lime mud mounds (300 m thick) developed. Thin tabular lime mud mounds developed in cyclic back-mound lithofacies. Similar fore-mound lithofacies thickened in a southerly direction. As many as 50 cycles developed in Middle Pennsylvanian to Lower Permian rocks. Eustatic sea level changes caused by late Paleozoic glaciation controlled cyclic sedimentation.

Syndepositional faulting in Atokan, Desmoinesian, and Virgilian times also had the effect of keeping the northern and eastern parts of the study area in the marine photic zone. This area may have constituted a paleohorst within the Oquirrh basin in Pennsylvanian and Permian times.

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