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A Petrographic, Geochemical and Isotopic(Sr, O, H and C) Investigation of Alteration Minerals in Volcaniclastic Rocks at Minna Bluff, Antarctica: Petrogenesis and Implications for Paleoenvironmental Conditions

Antibus, Joanne Vinopal
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1339771052

Abstract Details

2012, Master of Science (MS), Bowling Green State University, Geology.
The petrography and geochemistry of alteration minerals in volcaniclastic deposits at Minna Bluff; a 45 km-long volcanic peninsula in the southern Ross Sea that was active between 12 and 4 Ma, are used to reconstruct environmental conditions during their formation. The volcaniclastic deposits are intercalated with lavas and domes and include hyaloclastite, breccia, tuff and sediments. The restricted size and extent of the deposits attest to the ephemeral nature of magma water interaction at Minna Bluff. The paragenesis of alteration minerals reveal phillipsite to form first followed by chabazite and/or carbonates. Carbonates include calcite, low to high Mg calcite (MgCO3 >4%), dolomite, magnesite, siderite and rhodochrosite. Alkali ratios (Na+K/Ca) are high for zeolites (phillipsite <1 to 154 and chabazite 8 to 97) relative to host lavas (<1 to 14). Chemical zoning in zeolites is poorly developed but in carbonates transects show significant variations in Fe, Mn and Sr and Mg/Ca ratios. Carbonate δ18O and δ13C values range from -0.50 to 21.53‰ and -1.04 to 8.98‰, respectively. Chalcedony δ18O and δD values range from 0.68 to 10.37‰ and -187.8 to -220.6‰, respectively. The deuterium values are in the range of Antarctic meteoric water. Carbonate 87Sr/86Sr ratios average 0.70327 ± 0.0009 (1σ) and are within the range of volcanic rocks from the Erebus Volcanic Province. The isotopic evidence indicates that meteoric water (ice/snow) was most likely responsible for the alteration of volcaniclastic rocks at Minna Bluff. Based on zeolite stability and the 13C-18O paleothermometer, the alteration occurred at elevated temperatures (5° to ~100°C), probably during or relatively soon after deposition. High δ18O for Mg-rich carbonates and some quartz suggest 18O enrichment by evaporative distillation from steam vents. The calculated δ18O of water (-25 to -16‰) reveal a broad shift from lighter to heavier values between ~11 Ma and ~8.5 Ma. A warming climate during this period has also been predicted based on sedimentary sequences within core recovered from the nearby ANDRILL AND-1B drillcore.
Kurt Panter, PhD (Advisor)
Thom Wilch, PhD (Committee Member)
John Farver, PhD (Committee Member)
Jeff Snyder, PhD (Committee Member)
272 p.
Geology; Paleoclimate Science
hyaloclastites; Minna Bluff, Antarctica; Sr, O, H isotopes; paleoenvironments; volcaniclastic alteration minerals

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Citations

  • Antibus, J. V. (2012). A Petrographic, Geochemical and Isotopic(Sr, O, H and C) Investigation of Alteration Minerals in Volcaniclastic Rocks at Minna Bluff, Antarctica: Petrogenesis and Implications for Paleoenvironmental Conditions [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1339771052

    APA Style (7th edition)

  • Antibus, Joanne. A Petrographic, Geochemical and Isotopic(Sr, O, H and C) Investigation of Alteration Minerals in Volcaniclastic Rocks at Minna Bluff, Antarctica: Petrogenesis and Implications for Paleoenvironmental Conditions. 2012. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1339771052.

    MLA Style (8th edition)

  • Antibus, Joanne. "A Petrographic, Geochemical and Isotopic(Sr, O, H and C) Investigation of Alteration Minerals in Volcaniclastic Rocks at Minna Bluff, Antarctica: Petrogenesis and Implications for Paleoenvironmental Conditions." Master's thesis, Bowling Green State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1339771052

    Chicago Manual of Style (17th edition)

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© 2012, all rights reserved.
This open access ETD is published by Bowling Green State University and OhioLINK.