Extinction of deep-sea foraminifera as a result of Pliocene–Pleistocene deep-sea circulation changes in the South China Sea (ODP Sites 1143 and 1146) |
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| Institution: | 1. Geomarine Research, 49 Swainston Road, St Johns, Auckland, New Zealand;2. Institut für Geowissenschaften, Christian-Albrechts-Universität Olshausenstraße 40, 24118 Kiel, Germany;1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;2. Department of Oceanography, Texas A&M University, TAMU 3146, College Station TX 77840-3146, USA;1. CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;2. CAS Key Laboratory of Ocean and Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;3. Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China;4. MLR Key Laboratory of Marine Mineral Resources, Guangzhou Marine Geological Survey, Guangzhou 510075, China;5. Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China;1. Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China;2. Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China;3. School of Earth Sciences and Engineering, Sun Yat-Sen University, Guangzhou 510275, China;4. Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146 Hamburg, Germany;5. Guangzhou Marine Geological Survey, Guangzhou 510075, China;6. Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China;1. State Key Laboratory of Marine Geology, Tongji University, 1239 Siping Road, 200092 Shanghai, China;2. MARUM – Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany;3. Department of Geological Oceanography and State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China |
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| Abstract: | During the Late Pliocene–Middle Pleistocene, 56 species and 15 genera of elongate, cylindrical benthic foraminifera disappeared from the deep sea in the South China Sea (ODP Sites 1143 and 1146) as part of the last global extinction in the deep sea. This extinction group (Ext. Gp) exhibited a pulsed decline in abundance and species richness mostly during glacials, and often associated with periods of expansion of polar ice that resulted from increased cooling of the Earth's climate since ～2.5 Ma, particularly during the Mid-Pleistocene Climate Transition (MPT, 1.2–0.6 Ma). We infer that the Ext. Gp decline in abundance and disappearance was a result of the increased glacial cooling and consequent increased ventilation of the deep-sea water masses. The detailed record of withdrawal of the Ext. Gp differs between the two sites, with far more disappearances occurring prior to the MPT in the deeper Site 1143 (2772 m) than in the shallower Site 1146 (2092 m). The Late Pliocene and Early Pleistocene declines in deeper parts of the South China Sea (Site 1143) may have resulted from enhanced glacial production of deep, southern-sourced water passing over the sill into the basin from the North-west Pacific. During the MPT however, the Ext. Gp declines and disappearances were of similar timing and magnitude in both sites, implying that both were influenced by the same deep-water mass during glacials at this time. This could have been North Pacific Deep Water, which many workers infer was formed in the northern Pacific during the last glacial, and may have begun forming during MPT glacials, in association with the progressively enhanced cooling of the Northern Hemisphere. |
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