--> Abstract: Coniacian to Lowermost Campanian Stratigraphy of the Austin Chalk, Northeast Texas, by Arafat A. AlShuaibi; #90078 (2008)

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Coniacian to Lowermost Campanian Stratigraphy of the Austin Chalk, Northeast Texas

Arafat A. AlShuaibi
Earth & Environmental Sciences, Kuwait University, Safat, Kuwait

The lithostratigraphy, biostratigraphy, and chronostratigraphy of the lower Coniacian to lowermost Campanian strata of the Austin Chalk and its equivalents in northeast Texas were studied. The Austin Chalk in Ellis, Dallas, Collin, and southern Grayson County is represented by the Atco, Bruceville, and the Waxahachie members. East of Grayson, Fannin, Lamar, and Red River counties, the Austin Chalk equivalents are represented by the Ector Member, the Bonham Mudstone Member, and the Gober Member.

The present study indicates that: (1) The Ector Member is the chronostratigraphic equivalent of the lower Coniacian part of the Atco Member; (2) The Bonham Mudstone and Bruceville members are both assignable to the Santonian; (3) The Gober and the Waxahachie members of the Austin Chalk are assignable to the lowermost Campanian. New biostratigraphic data have resulted in the revision of the planktonic foraminiferal zonation for Upper Cretaceous (lower Coniacian to lower Campanian) strata of the western Gulf Coastal Plain. Three superzones and four zones belonging to three chronostratigraphic units are established including: 1) Superzone UK4, Zone 4B (lower Coniacian) and Zone 4A (upper Coniacian); 2) Superzone UK3 (Santonian); and 3) Superzone UK2, Zone 2F (lowermost Campanian). One new genus and forty species of which seven are new are described from the Austin Chalk in the present study. The Family Marginotruncanidae Pessagno is emended herein to include all taxa possessing extraumbilical-non umbilical primary apertures. One new genus Pessagnoella has been erected under the Marginotruncanidae. Six new species: Marginotruncana pseudoelevata, M. tenmilecreekensis, Pessagnoella ectorensis, P. mansfieldensis, Whiteinella cherifi and W. mountaincreekensis have been erected under the Marginotruncanidae.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas