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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 63 (1979)

Issue: 3. (March)

First Page: 418

Last Page: 418

Title: Middle Paleozoic Sedimentation and Paleogeography of Southern Great Basin: ABSTRACT

Author(s): Gretchen L. Bender, Richard H. Miller

Article Type: Meeting abstract

Abstract:

Based on detailed analysis of conodont distribution, middle Paleozoic rocks in the southern Great Basin have been divided into refined time intervals. These include late Middle through Late Ordovician; early to middle Early Silurian; late Early Silurian; Late Silurian; and Early to early Middle Devonian. Rocks of these intervals consist of fine-grained limestone, fine to medium-grained dolostone, and lesser amounts of silty limestones and impure calcareous shales. Based on the distribution of lithofacies, deposition occurred on an eastern craton margin and within inner- and outer-shelf regions on the Cordilleran miogeocline. Offset of these regions can be used to estimate movement along major faults (e.g., the Death Valley-Furnace Creek fault zone).

The craton margin was a region of supratidal to very shallow subtidal environments during part of this time interval. Regression and erosion of the craton margin during Early and Late Silurian time provided a source of carbonate mud as well as silt to sand-sized quartz which were redeposited on the shelf areas in the west. An unconformity separates Upper Ordovician rocks from overlying Lower Devonian rocks. Intertidal to subtidal environments with nearly continuous deposition existed on the inner shelf, providing evidence of regional regression during early and middle Early Silurian and Late Silurian time. The outer shelf was an area of complex environments including platforms and local basins. Uplift and erosion in Late Silurian time affected part of the outer shelf. In the northern nyo Mountains an unconformity separates upper Lower Silurian rocks from overlying Lower Devonian rocks.

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