HR: 0800h
AN: PP41A-0581    [Abstracts]
TI: Perturbations to the Carbon and Sulfur Cycle During the Permian-Triassic Boundary Event in Southern China
AU: * Riccardi, A L
EM: ariccard@geosc.psu.edu
AF: The Pennsylvania State University, 511 Deike Building, Department of Geosciences, University Park, PA 16802 United States
AU: Arthur, M A
EM: arthur@geosc.psu.edu
AF: The Pennsylvania State University, 511 Deike Building, Department of Geosciences, University Park, PA 16802 United States
AU: Arthur, M A
EM: arthur@geosc.psu.edu
AF: University of Rhode Island, Graduate School of Oceanography, Narragansett, RI 02882 United States
AU: Kump, L R
EM: lkump@psu.edu
AF: The Pennsylvania State University, 511 Deike Building, Department of Geosciences, University Park, PA 16802 United States
AU: D'Hondt, S
EM: dhondt@gsosun1.gso.uri.ed
AF: University of Rhode Island, Graduate School of Oceanography, Narragansett, RI 02882 United States
AB: The Permian-Triassic boundary (251 Ma) is a time of major change in the chemistry of the oceans, as well as the period of the greatest mass extinction of the Phanerozoic. The cause of these changes remains a subject of intense research. Many of the current theories rely on changes to the oceanic sulfur cycle. Carbonate associated sulfate has the potential to provide a high resolution record of variations in the concentration and stable isotopic composition of seawater sulfate. This is of interest because the majority of the current data in this area is from evaporites or pyrites both of which are relatively rare in the stratigraphic record. The isotopic value of seawater sulfate is known to shift from approximately $13\permil$ in the late Permian to $35\permil$ during the early Triassic. Our research focuses on CAS found in marine carbonates, and we have obtained samples from two sections that span the Permian-Triassic boundary (PTB) of the Meishan and Changxi sections located in Southern China. The carbonates were powdered and the CAS was extracted as barite. Sulfate content peaks at the event horizon at Meishan, indicating perhaps either substantial changes in local (or global) surface ocean chemistry, pH changes, or changes in rates of mineral precipitation. Isotopic analysis of the CAS provides a detailed record of the isotopic shift is $\delta$$^{34}$S across the PTB in two temporally constrained sections, and $\delta$$^{18}$O of sulfate also aids in our evaluation of the timing and extent of ocean anoxic events. The $\delta$$^{13}$C of kerogen at Meishan reaches a minimum just before the event horizon and the point of lowest $\delta$$^{13}$C for carbonate. This differs from many other PTB sections where both sets of carbon isotopes reach a minimum simultaneously. This is not as clear in the Changxi section where the event horizon is not as well resolved. The possibility of primary or secondary diagenetic alteration is also being examined for both sections. The combination of these two data sets provides a concise temporal record of changes in the oceanic sulfur cycle, as well as the changes in the carbon cycle across the PTB.
DE: 4870 Stable isotopes
DE: 4267 Paleoceanography
DE: 1050 Marine geochemistry (4835, 4850)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting