Semester of Graduation

Spring 2024

Degree

Master of Science (MS)

Department

Geology and Geophysics

Document Type

Thesis

Abstract

In this study, a deepwater well from the Alaminos Canyon (AC 857#1), located in the northwestern Gulf of Mexico (GoM), is analyzed for marine and terrestrial palynomorphs to develop a Thanetian to Ypresian biostratigraphic scheme. One hundred and twenty-one drill cutting samples from the Wilcox Group were selected for analysis with measured depths ranging from 3,995 m to 5,181 m. Previous deepwater palynology studies of the Wilcox Group are overwhelmingly proprietary, making this one of the first opportunities to analyze the palynology of deepwater Wilcox Group sediments. The assemblages demonstrated excellent preservation of palynomorphs and a general increase in terrestrial diversity from the lower to upper samples. The average concentration of terrestrial palynomorphs throughout the well was 2,829 specimens per gram of dried sediment and 673 specimens of dinoflagellate cysts per gram of dried sediment, with both groups experiencing a gradual decline in concentration from the lower to upper samples. The most common terrestrial species were Cupressacites hiatipites, Betulaceae/Myricaceae types, the Juglandaceae family, Retitricolporites spp., and Deltoidospora, all indicating a coastal swamp or warm-temperate environment. Statistical analysis indicated four species drove the majority of the changes seen in assemblages; Thomsonipollis magnificus, Betulaceae/Myricaceae, Retitricolporites spp., and Cupressacites hiatipites. The most common dinoflagellate cysts recovered belong to the Apectodinium, Spiniferites, Polysphaeridium, Lingulodinium, and Operculodinium genera. The presence of significant climate events during the Paleogene, like the Paleocene-Eocene Thermal Maximum (PETM) and the Early Eocene Climatic Optimum (EECO), are detectable in variations of the recovered palynological assemblages. The PETM reflects a period of rapid global warming during which the Gulf of Mexico experienced a rise in sea level, increased precipitation, and the expansion of tropical climates to higher latitudes. This event is marked by a dinocyst assemblage dominated by Apectodinium and the last appearance datum of Apectodinium augustum. The EECO marks a prolonged period of warming with high biological turnover and is indicated in samples by an increase in the diversity of terrestrial palynomorphs. The Bureau of Ocean Management (BOEM) biostratigraphic report provided limited age controls with the presence of only four nannofossil biostratigraphic events occurring within this well, and all of them restricted to the upper third of the sampled interval. This study proposes the addition of nine biostratigraphic events to the biosteering framework for AC 857 #1; five acmes (Thomsonipollis magnificus, Apectodinium spp., Apectodinium homomorphum, and two of Spiniferites spp.), three last appearance datums (Thomsonipollis magnificus, Apectodinium augustum, and Momipites actinus), and one first appearance datum (Areosphaeridium diktyoplokum). These biostratigraphic events correspond to established zones Paly 5 to Paly 8 of Zarra et al. (2019), indicating the sampled interval of AC 857 #1 is well within the Upper Wilcox.

Date

1-22-2024

Committee Chair

Warny, Sophie

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Available for download on Monday, January 20, 2031

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