T115 Sedimentary, Paleobiologic, and Geochemical Studies of Deep Time Ocean-Climate Perturbations I: Honoring the Scientific Contributions of Michael A. Arthur

Monday, 26 September 2016
8:00 AM - 12:00 PM
Room 402

MULTI-BASIN BIOAPATITE RECORDS OF CARBONIFEROUS SEAWATER SR ISOTOPIC COMPOSITION

Paper number: T115-7
Program: Technical Sessions
Time: 9:30 AM – 9:45 AM

Authors

  • Jitao Chen Presenting Author
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing
  • Jitao Chen Presenting Author
    University of California, Davis, Davis, CA
  • Dillon J. Osleger
    University of California Santa Barbara, Santa Barbara, CA
  • Dillon J. Osleger
    University of California, Davis, Davis, CA
  • Isabel Montanez
    University of California, Davis, Davis, CA
  • Yuping Qi
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing
  • Qiulai Wang
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing
  • Xiangdong Wang
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing

Abstract

Seawater Sr isotopic composition has been used as a chronostratigraphic correlation tool and as a proxy for long-term variations in global climate and tectonics throughout the Phanerozoic. The Carboniferous was a time of extensive glaciation, major global tectonic reconfiguration, and a series of climatic and oceanic perturbations, and thus these events should be recorded in Carboniferous seawater 87Sr/86Sr. The existing seawater Sr isotopic record, reconstructed from bulk carbonate and brachiopod calcite, however, remains moderately resolved, limiting its chronostratigraphic and proxy potential. The resolution of the existing record reflects biostratigraphic uncertainties in multi-basin records, limited temporal resolution, and variable degrees of diagenetic alternation.

Here we present high-resolution 87Sr/86Sr records of conodont apatite integrated with detailed conodont biostratigraphy from the Naqing section, south China of the eastern Paleotethys Ocean region and Donets Basin, Ukraine of the western Paleotethys. The carbonate slope succession of Naqing provides a continuous depositional records, whereas the Donets Basin provides a U-Pb calibrated, short-eccentricity record of a fluvial-deltaic to shallow-marine carbonate succession. The newly acquired 87Sr/86Sr data show an overall rise through the Pennsylvanian beginning with a nadir in the middle Visean to the apex in the middle Bashkirian, followed by a decline in earliest Gzhelian. Our records show previously unrecognized changes in rise rate of 87Sr/86Sr as well as superimposed with 1–2 myr fluctuations in Bashkirian to the early Gzhelian. Notably a Sr isotope plateau characterizes late Bashkirian through first half of Moscovian, coinciding with a major periods of Pennsylvanian glaciation recorded in the Donets onlap-offlap curves. Comparison of conodont 87Sr/86Sr values with diagenetically screened micrite and brachiopod values exhibits variable differences, with greatest discrepancies between coexisting micrite and conodont. The new high-resolution seawater Sr isotope curve, when integrated with contemporaneous sea level, glaciation history, and δ13C and δ18O records, provides new insight into the interplay between climate and tectonics during the late Paleozoic ice age.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-282871

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