Records of Toba eruptions in the South China Sea -Chemical characteristics of the glass shards from ODP 1143A |
| |
Authors: | LlANG Xirong WEI Gangjian SHAO Lei LI Xianhua WANG Rucheng |
| |
Institution: | 1. Guangzhou Institute of Geochemistry, Chinese Academy of sciences, Guangzhou 510640, China;National Key Laboratory of Metallogenetics, the Department of Geosciences, Nanjing University, Nanjing 210093,China 2. Guangzhou Institute of Geochemistry, Chinese Academy of sciences, Guangzhou 510640, China 3. Key Laboratory of Marine Geology, Ministry of Education, Tongji University, Shanghai 200092, China 4. National Key Laboratory of Metallogenetics, the Department of Geosciences, Nanjing University, Nanjing 210093,China |
| |
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, lay ers 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, erupt ing 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. |
| |
Keywords: | South China Sea ODP 1143 Site tephra shards Toba eruptions monsoon |
本文献已被 万方数据 等数据库收录! |
|