Semester of Graduation

Fall 2023

Degree

Master of Science (MS)

Department

Geology and Geophysics

Document Type

Thesis

Abstract

Palynological analyses of Late Paleocene to Early Eocene drill cutting samples from the deepwater Wilcox Group in the northern Gulf of Mexico were analyzed to provide Paleocene/Eocene environmental data and to create a biosteering scheme to be used for future Gulf of Mexico exploration. Fifty-three drill cutting samples were analyzed from Walker Ridge (WR) 508 #1 in the Stones field, with a measured depth ranging from 8,056 to 8,723 m. These samples yielded mainly low diversity terrestrial assemblages dominated by pollen belonging to the Betulaceae, Myricaceae, Cupressaceae/Taxodiaceae and Juglandaceae families. This denotes an environment quite similar to what is found in coastal Louisiana today. Vegetation composition does not change drastically but varies slightly from more swamp-like vegetation in the Paleocene to more coastal fringing forest plants in the Eocene. Concentrations in palynomorphs are generally low throughout the section, with terrestrial palynomorphs averaging 3,123 specimens per gram of dried sediment and dinoflagellate cysts averaging 94 specimens per gram of dried sediment. The most common dinoflagellate cysts recovered include species of Spiniferites, Operculodinium and Polysphaeridium, along with Adnatosphaeridium multispinosum, and Lingulodinium machaerophorum. The low concentration in dinoflagellate cysts recovered suggests a high depositional rate diluting the marine organic fraction in turbidity currents. These turbidity currents are also evidenced by the dominance of reworked Mesozoic dinoflagellate cysts in a turbidite sand interval at a bottom depth of 8,065m. This study provides a critical biosteering scheme that refines the limited age control for the WR 508 #1 well available from the Bureau of Ocean Energy Management (BOEM), which is based only on four nannofossil biostratigraphic events and one local foraminifera event. Here, eleven new biosteering events are proposed for well WR 508 #1, including two acmes (Apectodinium spp. and Alnus verus), four First Appearance Datums (FADs of Caryapollenites veripites, Insulapollenites rugulatus, Pistillipollenites mcgregorii, and Areosphaeridium diktyoplokum) and five Last Appearance Datums (LADs of Momipites actinus, Momipites anellus, Pistillipollenites mcgregorii, Insulapollenites rugulatus and Nudopollis terminalis). The Stones Field Well WR 508 #1 biostratigraphic events observed in this study places the well within biostratigraphic zones Paly 3 to Paly 7 of Zarra et al. (2019). Overall, the results from this study place the Stones Field Well WR 508 #1 in deepwater Lower and Upper Wilcox turbidites.

Date

11-15-2023

Committee Chair

Warny, Sophie

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