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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: Allochthonous Carbonate Rocks in Toe-of-Slope Deposits (Permian, Guadalupian), Guadalupe Mountains, West Texas: ABSTRACT

Author(s): Allan G. Crawford

Article Type: Meeting abstract


Channelized allochthonous carbonate toe-of-slope deposits, equivalent to the Goat Seep Dolomite, and possibly the Getaway Bank, are well exposed along the west face of the Guadalupe Mountains. There are five rock types present: (1) fine rudite conglomerate, (2) carbonate megabreccia, (3) oolitic packstone/grainstone, (4) wavy-laminate wackestone, and (5) thin-bedded sandstone/siltstone. The rudites (~ < 1.0 m thick) appear to have been deposited by laminar debris flows, as evidenced by clasts aligned parallel to bedding, a non-erosive base, and the presence of a rigid plug. In contrast, the megabreccias (> 2 m thick) may have been deposited by turbulent debris flows, based on their erosional bases and lack of aligned clasts. The other rock types are interpreted to h ve been deposited by fluid density flows and turbidity flows.

The carbonate rocks in the toe-of-slope strata occur in lens-shaped deposits (0.5 km wide × 30 to 50 m deep) that are surrounded by sandstone and siltstone. The lenses are interpreted as basinward-trending channels that have been filled with shelf- and shelf-edge derived sediments deposited at the base of a carbonate buildup. The channels are typically filled with megabreccia at the base, consisting largely of shelf-edge debris, which is overlain by finer rudites and/or oolitic packstone/grainstone, consisting largely of shelf-derived debris. It is interpreted that the megabreccias were derived from large slumps or slides near the shelf-edge and that the shelf-derived sediments were later carried across the shelf-edge and were deposited in the toe-of-slope as separate, finer unit .

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