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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 46 (1996), Pages 333-344

South Texas Ingleside Barrier; Coastal Sediment Cycles and Vertebrate Fauna. Late Pleistocene Stratigraphy Revised

Ervin G. Otvos, Wade E. Howat

ABSTRACT

Three sedimentary cycles, including alluvial, inshore-, and nearshore units were identified in the highest Beaumont interval. Unconformities, outlined by oxidized and caliche-rich zones, abrupt lithologic, and biotope changes separate them. The youngest pre-Ingleside barrier unit unconformably underlies and continues landward of the mainland barrier sectors. Thin muddy sands of the Encinal and south Live-Ingleside sectors rest unconformably on the youngest pre-Ingleside barrier surface, misinterpreted previously as the barrier's lagoon plain. The northern Ingleside, Aransas, and Seadrift barrier sectors overlie a thicker transgressive sequence. In contrast with southern Live Oak, barrier-correlative Sangamonian Interglacial alluvium occurs here, subdivided by unconformities. The prograding barrier sequence filled a broad, shallow embayment. Contrary to the generally accepted Wisconsinan age, amino acid racemization data confirm the Sangamonian age of the barriers, including correlation with the NE Gulf coast Gulfport barrier trend.

Core data refuted two conflicting views, claiming the thick multistory, respectively, very thin character of Ingleside barrier sands. Suggested fossil indicators of Sangamonian sea-levels are inadequate to support a subsequent tectonic upwarp. Wisconsinan deflation reduced, even eliminated strandplain topography. Few large dunes, and thousands of eolian pimple mounds cover certain barriers. Ponds occupied blowout hollows in the barriers. Bones of radiometrically non-datable Rancholabrean vertebrates were mixed with pond fill during a warmer and wetter Wisconsinan lowstand.


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