High-Resolution Calcareous Nannofossil Biostratigraphic Applications: Examples from the Upper Cretaceous Southern Ocean (ODP Leg 183) and Paleocene Equatorial Atlantic (ODP Leg 207)

• Other Authors: Mitchell-Tapping, Aleta M. (authoraut), Wise, Sherwood W. (professor directing dissertation), Keller, Laura (university representative), Parker, William C. (committee member), Wang, Yang (committee member), Burnett, William (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution)
• Format: Text
• Language: English
• Published: Florida State University
• Subjects: Earth sciences; Oceanography; Atmospheric sciences; Geophysics; Keller; Kerguelen; Southern Ocean
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-7932; http://fsu.digital.flvc.org/islandora/object/fsu%3A253349/datastream/TN/view/High-Resolution%20Calcareous%20Nannofossil%20Biostratigraphic%20Applications.jpg

This dissertation is a collection of high-resolution calcareous nannofossil biostratigraphic projects. The projects are from Ocean Drilling Program (ODP) Leg 183 to the Kerguelen Plateau (Hole 1138A) and ODP Leg 207 to the Demerara Rise, off the coast of Suriname South America (Hole 1258A). These projects illustrate the important contribution of calcareous nannofossil biostratigraphy in understanding the paleoceanography of these regions. Chapter 2 details the results of a high-resolution biostratigraphic calcareous nannofossil study on Oceanic Anoxic Event 2 (OAE2) on the Kerguelen Plateau in the Southern Ocean. The distinct lack of calcareous nannofossils led to the delineation of OAE2 and suggests that anoxia had expanded to within the photic zone of the surface water column, indicating a collapse in the vertical stratification of these waters. A rise in sea level expanded this anoxia to shallower areas, whereby the leaching of nutrients led to fertilization and productivity in the ocean basin. In addition, the finding of a recurring post-anoxic event indicates that these oceanic conditions continued into the Turonian and signified changing sea surface temperatures and salinity levels that affected surface circulation patterns, unique to this basin. These findings are significant in identifying additional hydrocarbon deposits. Chapter 3 presents the results from another high-resolution calcareous nannofossil biostratigraphic study from the Kerguelen Plateau. This study delineates 16 bioevents spanning the Coniacian to Santonian. Five of these 16 bioevents have been previously discussed in the literature. Eleven new bioevents are identified in this study. The abundance of r-selected taxa in these samples suggests cool, eutrophic surface water conditions during this time. Chapters 4 and 5 examine calcareous nannofossils from lower Paleocene sediments of Hole 1258A on ODP Leg 207 to the Demerara Rise off Suriname, South America. An overall increasing trend in calcareous nannofossil diversity is consistent with other lower Paleocene studies. A warm-water environment is interpreted for the lower Paleocene, with cool-water incursions. This study examines the paleoecological response of calcareous nannofossils after a mass extinction event. From this same material, a new species is identified, Bomolithus lucidus, that is described in Chapter 5. Chapter 6 analyzes lower Paleocene sediment from Hole 1259B from ODP Leg 207 to delineate intervals in which Braarudosphaera taxa were found. The geographic restriction of the Braarudosphaera blooms to the Atlantic Ocean has been noted in numerous studies. It is proposed that parallel transform faults had enough vertical relief to act as a barrier and restrict circulation. The influx of nutrients and fresh water from the continent would also have supported an environment conducive to bloom events. A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Spring Semester, 2013. March 8, 2013. Includes bibliographical references. Sherwood W. Wise, Jr., Professor Directing Dissertation; Laura Keller, University Representative; William C. Parker, Committee Member; Yang Wang, Committee Member; William Burnett, Committee Member.