The Kasimovian (late Pennsylvanian) to early Roadian (middle Permian) is an interval of Earth history that experienced relatively stable climatic conditions highlighted by significant glaciation, which might represent an analog for current and future climate dynamics. The carbon isotope (δ13C) record during this interval is relatively stable with a few minor but relatively unexplored fluctuations of ~2‰, suggesting stable global OC burial even as peat and/or coal deposits declined at the end of the Permian. This suggests that carbon burial may have increased elsewhere, or changes in the inputs would be required to maintain a constant isotope record. One possibility is that marine OC burial increased to balance the waning peat and/or coal deposits. Enhanced marine OC productivity can possibly lead to increased burial, which would drive a global positive δ13C excursion. For example, the Midland Basin in Texas is characterized by significant Permian hydrocarbon source rocks, which may have affected the global carbon cycle and therefore isotope record. It is possible that there are other substantial marine sinks of OC during this time, but global distributions are not well-constrained. These deposits, however, may have been manifested as organic-rich black shale, or a small but widespread increase of OC globally, which could have accounted for the stability of the carbon isotope record. Resolving the potential mechanisms that may be driving local and global OC burial is imperative for understanding the Earth system feedbacks associated with ancient and potentially future climate perturbations. This research constrains local and potentially global marine redox conditions using a multi-geochemical proxy approach. Total OC contents and isotopes were analyzed to constrain local to global burial, respectively. Iron speciation and δ34Spyr were utilized to constrain local redox conditions – including local anoxic and euxinic (anoxic and sulfidic water-column) conditions and pyrite burial. Redox-sensitive trace metals were measured to interpret local conditions, which are best utilized in combination with Fe speciation, and under certain circumstances can help to decipher basin restriction or global trace metal drawdown due to widespread euxinia. Last, thallium isotopes have been analyzed on anoxic to euxinic samples to determine the global extent of oxic bottom waters and the basin’s connectivity to the open ocean. The combination of these traditional and novel geochemical redox proxies provide new context to interpret the local depositional environment of the Midland Basin. The collected results show that the black shales in the Midland Basin were deposited under low oxygen conditions and at a few points verging on euxinic. The data suggest that eustatic sea levels increased during sediment deposition. Associated with this sea level rise was an increase in bioessential nutrient availability (e.g., trace metals), which led to increased organic carbon drawdown and preservation within the basin. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2019. / April 8, 2019. / Includes bibliographical references. / Jeremy Owens, Professor Directing Thesis; Seth Young, Committee Member; Yang Wang, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_709718 |
| Contributors | Bandy, Terryl L. (Terryl Lynn) (author), Owens, Jeremy D. (Professor Directing Thesis), Young, Seth A. (Committee Member), Wang, Yang (Committee Member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Earth, Ocean and Atmospheric Science (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, master thesis |
| Format | 1 online resource (49 pages), computer, application/pdf |
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