Masters Theses

Date of Award

6-1986

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Robert E. McLaughlin

Committee Members

Paul A. Delcourt, Thomas W. Broadhead

Abstract

A total of 30 samples were examined from Late Cretaceous strata in northeast Texas, exposed in an arc eight to twenty-four kilometers wide extending from Dallas north-northwest to the Arkansas boarder. Dinof1agel 1 ate palynomorphs extracted from these samples yielded a maximum in taxonomic richness of 114 taxa. The majority of the palynomorph specimens are represented by fifty genera, particularly within the families Gonyaulacacae and Peridiniaceae.

The stratigraphic ranges of the dinof1agel1 ate cysts within the northeast Texas section have been established, following the foramanifera zonation and calcareous nannoplankton zonation set up by Thompson (1983) and Percival (in press 1985) respectively.

In earlier palynological studies, Zaitzeff and Cross (1966) dealt with geographically related rocks, whereas Wilson (1974) examined the type Campanian and Maestrichtian sections in Holland, Belgium and Denmark. Identified in this study were twenty-three of the fifty-six dinof1agel1 ate taxa that Zaitzeff and Cross used to zone the Maestrichtian. Furthermore, based on both lithological and paleontological evidence, it has been determined that the Neylandville Marl portion of zone (A) from the Zaitzeff and Cross (1966) study, should be reassigned to the Taylor Group and is possibly Campanian in age.

Comparison with the Wilson (1974) study is limited to zones one and two of Wilson's five dinof1 age!1 ate zones, and thirty taxa in those zones were found to be in common with this study. Wilson used the first stratigraphic occurrence of Delflandre diebeliiAustraelia balmei and the last appearance of Austraelia hvidensis, (Ceratiopsis diebelii, Spinidinium clavum and Spinidinium densispinatum in this study) to identify the Campanian-Maestrichtian boundary in Denmark. In the Northeast Texas section both Ceratiopsis diebelii, and Spinidinium clavum are found in sediments of Campanian age, while the range of Spinidinium densispinatum continues into the Maestrichtian. Wilson uses the last strati graphic occurrence of Odontochitina operculata, O. costata, Senoniasphaera protrusa and S. rotunda to mark the Campanian-Maestrichtian boundary in the Maestricht region. In Northeast Texas, both Odontochitina operculata and O. Costata extend into the Maestrichtian, while Senoniasphaera protrusa and S. rotunda end within the Campanian. Cluster analysis was used to identify five dinoflagellate assemblages considered to be environmentally controlled by depositional environments. Four of these assemblages corresponds to particular lithologies associated with Annona, Gober, Brownstown and Marlbrook formations, respectively. The fifth assemblage is considered to be a transitional assemblage between two depositional environments. Statistical measures of dominance and taxonomic richness, the Gonyaulacaceae/Peridiniaceae ratio, and percent representation by family, were used in developing the relationships between dinof1agel1 ate taxa and five major depositional environments of the Late Cretaceous marine shelf in northeast Texas.

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