About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 33 (1983), Pages 269-273

Delineation of Delta Types: Norias Delta System, Frio Formation, South Texas

Edward A. Duncan (1)

ABSTRACT

The Norias delta system was the major depositional component of the Frio Formation, South Texas. The Norias was an expansive, predominantly sandy, progradational complex fed by the updip Gueydan fluvial system. This progradational complex effectively filled the Rio Grande Embayment of South Texas by the end of Frio deposition. Initiation of Norias deltaic progradation was probably associated with the early rise in sea level following a low-stand. As sea level rose following the lowstand, topographic expression of the pre-existing Vicksburg progradational wedge caused a northward deflection of the Gueydan fluvial system within the Rio Grande Embayment. Subsequently, the Norias delta complex was established as a stable progradational system in a position lateral to the north flanking margin of the main Vicksburg deltaic platform. The Norias delta system was flanked laterally with time equivalent depositional systems including a northerly strandplain/barrier bar system and to the south there are indications of a possible deltaic complex in northern Mexico. Entrenchment of the Vicksburg shelf during sea level lowstand probably led to the development of a submarine canyon adjacent to the south flank of the Norias delta system. Incorporated within the complex body of the progradational sequence, a well-defined evolution of Norias delta styles can be documented through the time of Frio deposition. Early Norias high-constructive fluvially dominated lobate geometries were characterized by meandering distributary systems as well as thick delta front and delta margin sands. Middle Norias deltaic deposits continued to be generally high-constructive lobate in style, but evidence for significant reworking of deltaic sediments can be inferred based on the strandplain/barrier system developed to the north. Late Norias deltas were high-destructive wave dominated in nature. Essentially the Norias depositional complex had become a broad alluvial plain feeding a strandplain/barrier bar system with little physiographic expression of a delta lobe.


Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24