| Magnetic records of Core MD77-181 in the Bay of Bengal and their paleoenvironmental implications |
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| 作者姓名： | LI Haiyan ZHANG Shihong FANG Nianqiao WANG Hongqiang |
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| 作者单位： | State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China |
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| 基金项目： | Acknowledgements The authors thank Zhou Liping, Zhu Yanming, Chcn Haiying and Bai lingyan for their assistance in the laboratory. They arc grateful to Liu Qingsong and another anonymous reviewer for their comments. This work was jointly supported by the National Basic Research Program of China （973 Program） （Grant No. 2006CB701400）, Ministry of Education （Grant No. NCET-04-0727） and the National Natural Science Foundation of China （Grant No. 40272074）. |
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| 摘 要： | Located in the low latitude region of the northeastern Indian Ocean, the Bay of Bengal represents one of the largest marginal seas in the world. The Bengal Fan hosts erosional products mostly from Himalayas and is under the influence of the Indian monsoon system. The Bengal Fan has thus been one of the ideal places for studying the uplift of the Tibet Plateau and the history of the Indian monsoon1―8]. The intensity of the Indian monsoon is controlled by secular variations in insola- ti…
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| 关 键 词： | 磁记录 岩化作用 北印度洋 古环境 MD77-181 |
| 文章编号： | 10.1007/s11434-006-2057-5 |
| 收稿时间： | 2006-03-08 |
| 修稿时间： | 2006-03-082006-06-08 |
Magnetic records of Core MD77-181 in the Bay of Bengal and their paleoenvironmental implications |
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| LI Haiyan ZHANG Shihong FANG Nianqiao WANG Hongqiang.Magnetic records of Core MD77-181 in the Bay of Bengal and their paleoenvironmental implications[J].Chinese Science Bulletin,2006,51(15):1884-1893. |
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| Authors: | Haiyan Li Shihong Zhang Nianqiao Fang Hongqiang Wang |
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| Institution: | (1) State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, 100083, China |
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| Abstract: | High-resolution environmental magnetic measurements were carried out on Core MD77-181 in the Bay of Bengal, including magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization of all samples, and tem- perature-dependence of magnetic susceptibilities and magnetic hysteresis parameters of representa- tive samples. The results suggest that (1) the mag- netic mineral assemblage of the upper 9.82 m sedi- ments (corresponding to the last 160 ka) is domi- nated by pseudo-single domain magnetite, with more abundant coarse grains in glacial periods than in in- terglacial periods; (2) the uppermost 6.50 m of sedi- ments (corresponding to the last 70 ka) shows sig- nificant temporal variations in grain sizes of magnetic minerals, possibly reflecting the teleconnection be- tween variations of the Indian summer monsoon and rapid cold events of the North Atlantic (Heinrich events); (3) the sediments below 9.82 m are domi- nated by paramagnetic minerals (probably including pyrites), suggesting reductive diagenesis. The mag- netic records of Core MD77-181 are comparable to those of Core MD77-180 in the Bay of Bengal, and ODP Hole 722B in the Arabian Sea. This study sug- gests that the paleoceanographic event at ~160 ka significantly changed the redox state of the northern Indian Ocean, from a reductive environment before the event to an oxic or suboxic environment after the event. |
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| Keywords: | environmental magnetism reductive diagenesis north- ern Indian Ocean ~160 ka |
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