The oldest mid-oceanic carbonate buildup complex: Setting and lithofacies of the Vendian (Late Neoproterozoic) Baratal limestone in the Gorny Altai Mountains,Siberia |
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Authors: | Yuko Uchio Yukio Isozaki Tsutomu Ota Atsushi Utsunomiya Mikhail M Buslov Shigenori Maruyama |
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Institution: | *)Dept. Earth and Planetary Science, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo 152-8551, Japan; **)Dept. Earth Science and Astronomy, University of Tokyo, 3-8-1, Komaba, Meguro, Tokyo 153-8902, Japan; ***)United Institute of Geology, Geophysics and Mineralogy, Siberian Branch of Russian Academy of Science, Novosibirsk 630090, Siberia, Russia |
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Abstract: | The Baratal limestone in the Gorny Altai Mountains, southern Siberia, occurs as large allochthonous blocks within a Cambrian accretionary complex that developed around the Siberia craton. Before the final accretion to Siberia in the Cambrian, the terrigenous clastic-free Baratal limestone was deposited directly upon a basaltic basement with a geochemical signature identical to that of modern oceanic plateau. The Baratal limestone with 598 ± 25 Ma (Early Vendian) Pb-Pb isochron age consists of three distinct facies; 1) massive lime mudstone with ooids and stromatolites, 2) bedded lime mudstone, and 3) limestone conglomerate/breccia dominated by ooid-bearing lime mudstone clasts. The first represents a shallow marine environment on top of an ancient oceanic plateau, while the latter two represent the deeper slope to bottom-of-slope facies of a plateau. The Vendian Baratal limestone provides the oldest example of a reconstructed shallow marine carbonate buildup complex developed on a plateau/seamount in a mid-ocean. |
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Keywords: | Vendian seamount carbonate buildup Altai Siberia |
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