Records of Toba eruptions in the South China Sea |
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Authors: | Xirong Liang Gangjian Wei Lei Shao Xianhua Li and Rucheng Wang |
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Institution: | (1) Guangzhou Institute of Geochemistry, Chinese Academy of sciences, 510640 Guangzhou, China;(2) Key Laboratory of Marine Geology, Ministry of Education, Tongji University, 200092 Shanghai, China;(3) National Key Laboratory of Metallogenetics, the Department of Geosciences, Nanjing University, 210093 Nanjing, China |
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Abstract: | Three layers of volcanic tephra, sampled from ODP 1143 Site in the South China Sea, were observed at the mcd depth of 5.55
m, 42.66 m, and 48.25 m, and named, in this paper, layers of A, B, and C, respectively. All of these tephra layers have an
average thickness of ca. 2 cm. They were constrained in age of ca. 0.070 Ma, ca. 0.80 Ma, and ca. 1.00 Ma, respectively, by
the microbiostratigraphy data. These tephra layers were predominated by volcanic glass shards with a median grain size of
70–75 μm in diameter. Major chemical compositions analyzed by EMPA and comparison with the previous data from other scatter
areas suggest that these three layers of tephra can correspond to the three layers of Toba tephra, YTT, OTT, and HDT, respectively,
erupting during the Quaternary. The occurrence of these tephra layers in the South China Sea implies that the Toba eruptions
often occurred in the summer monsoon seasons of the South China Sea during the Quaternary, and that the strength of eruptions
was probably stronger than that previously estimated. |
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Keywords: | South China Sea ODP 1143 Site tephra shards Toba eruptions monsoon |
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