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Strontium isotope stratigraphy and carbonate sedimentology of the latest Permian to Early Triassic in the western United States, northern Iran and southern China

Sedlacek, Alexa R.C.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1372971425

Abstract Details

2013, Doctor of Philosophy, Ohio State University, Geological Sciences.
Environmental perturbations associated with the late-Permian mass extinction and Early Triassic recovery are widely studied, and our understanding of global events during this biotic crisis continues to improve. Marine carbonates preserve geochemical proxy records of global change, including a rapid rise in seawater 87Sr/86Sr that began the near Guadalupian-Lopingian (Middle-Late Permian) boundary and continued through the end of the Early Triassic. Linking the increase in 87Sr/86Sr to enhanced weathering rates that resulted from environmental disturbances and terrestrial extinction during the latest Permian is inconsistent with the onset of the 87Sr/86Sr rise approximately 10 million years earlier at the end of the Middle Permian. However, several recent studies indicate that the rate of 87Sr/86Sr rise increased during the late Permian, and this rise may be the result of enhanced weathering rates during the extinction and recovery interval. This study improves the resolution of the seawater 87Sr/86Sr record of the late Permian through Early Triassic through analyses of whole rock samples collected from Zal, Iran and Dawen, South China. The carbonate succession at Zal, Iran preserves the entire Early Triassic and was previously analyzed for δ13C. Analyses of Sr isotopes at a resolution similar to the δ13C record enables direct comparison between these two records, and also allows for determinations in the changes in rate of strontium rise. The Permian-Triassic boundary interval was sampled at higher resolution by analyzing rocks from a biostratigraphically constrained sections deposited at Dawen on the Great Bank of Guizhou, South China. These results indicate that the rate of strontium rise increased during the latest Permian, possibly as a result of elevated weathering rates during the post-extinction interval. The final chapter of this dissertation examines marine carbonates from the Confusion Range, Utah, recently shown to represent relatively continuous deposition across the Permian-Triassic boundary. The proposed boundary interval consists of several distinctive lithologies which are similar in many regards to some Tethyan sections that contain microbially mediated carbonates of earliest Triassic age. Although microbial characteristics are found within the boundary interval of the Confusion Range section, future petrographic and chronostratigraphic studies are needed to determine if this microbial carbonate was deposited as part of a global event or simply reflect the local depositional environment.
Matthew Saltzman (Advisor)
William Ausich (Committee Member)
David Elliot (Committee Member)
Stig Bergstrom (Committee Member)
159 p.
Geology; Paleoclimate Science
Strontium isotope stratigraphy; Permian; Triassic; extinction; recovery; China; Iran; Great Basin; Utah

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Citations

  • Sedlacek, A. R.C. (2013). Strontium isotope stratigraphy and carbonate sedimentology of the latest Permian to Early Triassic in the western United States, northern Iran and southern China [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372971425

    APA Style (7th edition)

  • Sedlacek, Alexa. Strontium isotope stratigraphy and carbonate sedimentology of the latest Permian to Early Triassic in the western United States, northern Iran and southern China. 2013. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1372971425.

    MLA Style (8th edition)

  • Sedlacek, Alexa. "Strontium isotope stratigraphy and carbonate sedimentology of the latest Permian to Early Triassic in the western United States, northern Iran and southern China." Doctoral dissertation, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372971425

    Chicago Manual of Style (17th edition)

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