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Petrologic Insights into Basaltic Magma Genesis beneath East Antarctica

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2020, Master of Science (MS), Bowling Green State University, Geology.
Mt. Early and Sheridan Bluff are two Miocene volcanoes located near 87°S in the southern Transantarctic Mountains on the East Antarctic craton, ~1000 km away from any other exposed Cenozoic volcano associated with the West Antarctic Rift System (WARS). The basalts are unique in comparison with WARS, in that subalkaline (tholeiite) to alkaline (hawaiite and mugearite) magmas were nearly simultaneously generated during the Early Miocene (20 to 19 Ma). Close examination of isotopic measurements provide insight into mantle sources and cause of melting beneath the East Antarctic craton. Enriched isotopic signatures such as mildly elevated δ18O in olivine (average =5.55 ± 0.19 ‰) and whole rock 87Sr/86Sr ratios (0.7038-0.7049) indicate contamination by crustal material. However, the correlations between isotopes and major and trace elements (e.g. SiO2, MgO, Sr, and Zr) are either not seen or opposite of what would be expected for models for combined assimilation and fractional crystallization. Alternatively, the higher Sr and O and lower Nd and Pb isotopic values of Mt. Early and Sheridan Bluff samples compared to WARS basalts likely reflect crustal material within their mantle source (e.g., an EMII-like component). The isotopic variations shown by alkaline and tholeiitic basalts could be explained by different degrees of partial melting of a heterogeneous mantle containing crustal materials. Possible mechanisms to add crust is lithospheric delamination which occurred beneath this portion of the Transantarctic Mountains or recycled by past subduction zone processes.
Kurt Panter, Ph.D. (Advisor)
John Farver, Ph.D. (Committee Member)
Peter Gorsevski, Ph.D. (Committee Member)
125 p.

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Citations

  • Li, Y. (2020). Petrologic Insights into Basaltic Magma Genesis beneath East Antarctica [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1593363487482443

    APA Style (7th edition)

  • Li, Yuyu. Petrologic Insights into Basaltic Magma Genesis beneath East Antarctica. 2020. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1593363487482443.

    MLA Style (8th edition)

  • Li, Yuyu. "Petrologic Insights into Basaltic Magma Genesis beneath East Antarctica." Master's thesis, Bowling Green State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1593363487482443

    Chicago Manual of Style (17th edition)