Middle Permian organic carbon isotope stratigraphy and the origin of the Kamura Event |
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| Institution: | 1. Paleontological Institute, University of Zürich, Karl Schmid-Strasse 4, 8006 Zürich, Switzerland;2. Institute of Earth Surface Dynamics, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland;3. Department of Earth Sciences, University of Geneva, Geneva 1205, Switzerland;4. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China;1. Institute of Geology and Paleontology, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan;2. Department of Geoscience, University of Calgary, Calgary, Alberta T2N 1N4, Canada;1. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan;2. Laboratory of Ocean-Earth Life Evolution Research (OELE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho, Yokosuka 237-0061, Japan;3. Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan;4. Department of Earth Science and Astronomy, The University of Tokyo, Meguro, Tokyo 153-8902, Japan;5. Department of Chemistry, The University of Tokyo, Meguro, Tokyo 153-8902, Japan;6. Geology Institute, Chinese Academy of Geological Science, Beijing 100037, China;7. Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho, Yokosuka 237-0061, Japan;8. Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Midori, Yokohama 226-8503, Japan |
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| Abstract: | Large carbon cycle perturbations associated with the Middle Permian (Capitanian) mass extinction have been widely reported, but their causes and timing are still in dispute. Low resolution carbon isotope records prior to this event also limit the construction of a Middle Permian chemostratigraphic framework and global or local stratigraphic correlation, and hence limit our understanding of carbon cycle and environmental changes. To investigate these issues, we analyzed the 13Corg values from the Middle Permian chert-mudstone sequence (Gufeng Formation) in the Lower Yangtze deep-water basin (South China) and compared them with published records to build a chemostratigraphic scheme and discuss the underlying environmental events. The records show increased δ13Corg values from late Kungurian to early Guadalupian, followed by a decrease to the late Wordian/early Capitanian. The early-mid Capitanian was characterized by elevated δ13Corg values suggesting the presence of the “Kamura Event”: an interval of heavy positive values seen in the δ13Ccarb record. We propose that these heavy Capitanian δ13C values may be a response to a marked decline in chemical weathering rates on Pangea and associated reduction in carbonate burial, which we show using a biogeochemical model. The subsequent negative δ13C excursion seen in some carbonate records, especially in shallower-water sections (and in a muted expression in organic carbon) coincide with the Capitanian mass extinction may be caused by the input of isotopically-light carbon sourced from the terrestrial decomposition of organic matter. |
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| Keywords: | Guadalupian Capitanian mass extinction Chemostratigraphy Carbon cycle Emeishan volcanism |
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