| 南海北部晚渐新世与早中新世之交T60构造运动的古水深响应 |
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| 引用本文： | 王乙晶,金海燕,翦知湣,徐娟.南海北部晚渐新世与早中新世之交T60构造运动的古水深响应[J].海洋学报,2021,43(5):79-87. |
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| 作者姓名： | 王乙晶 金海燕 翦知湣 徐娟 |
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| 作者单位： | 同济大学 海洋地质国家重点实验室，上海 200092 |
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| 基金项目： | 国家重点研发计划（2018YFE0202400）；国家自然科学基金委员会?山东省人民政府海洋科学研究中心联合资助项目（U1606401）；自然资源部全球变化与海气相互作用专项（GASI-GEOGE-04）；国家自然科学基金（91428310，41630965） |
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| 摘 要： | 本文采用国际大洋发现计划(IODP)第368航次U1501站位井深264.0～331.1 m的样品，通过有孔虫壳体氧同位素地层和锶同位素定年，得出该段井深年龄为晚渐新世?早中新世20.3～32.0 Ma(地震反射不整合面T60的底部年龄在28～30.5 Ma左右)。T60构造运动之后，岩芯沉积物中有机碳含量、底栖有孔虫壳体稳定碳同位素δ13C、浮游与底栖有孔虫碳同位素差值Δδ13CP-B指示海水表层生产力的降低；碳酸钙含量、有机碳/氮比值反映了陆源物质输入的减少；结合浮游有孔虫相对丰度以及底栖有孔虫的属种组合变化，共同揭示了南海北部在晚渐新世?早中新世时期，区域构造沉降运动导致了U1501站位在T60之后古水深逐步加深、离岸距离变远，相关结论从微体古生物学角度为认识T60构造事件及其沉积环境变化提供了科学证据。
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| 关 键 词： | 南海北部 T60 古水深 表层生产力 |
| 收稿时间： | 2020-05-11 |
The response of paleo-water depth to T60 tectonic movement in the northern South China Sea during the late Oligocene to early Miocene |
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| Institution: | State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China |
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| Abstract: | Samples of International Ocean Discovery Program (IODP) 368 Site U1501 between core depth 264.0?331.1 m were collected and analyzed in this study. Through foraminifera oxygen isotopic stratigraphy and Sr isotopic dating, the age of this depth interval ranges from early Miocene 20.3 Ma to late Oligocene 32.0 Ma (with seismic reflector T60 bottom age at 28?30.5 Ma). After T60 event, 3 proxies including the content of organic carbon, stable δ13C of benthic foraminifera and the difference of δ13C between planktonic and benthic foraminifera (Δδ13CP-B) showed the sea surface paleo-productivity weakened; meanwhile, the carbonate content and the organic carbon/nitrogen ratio revealed the terrigenous input decreased. Combined with the changes of relative abundance of planktonic foraminifera and the benthic foraminifera faunal combinations, these paleo-environmental proxies implies that during late Oligocene to early Miocene, the regional tectonic subsidence in the northern South China Sea leaded to the deepening of the paleo-water depth and increasing the offshore distance at Site U1501 after the T60 event. These conclusions provide micropaleontology evidence for better understanding of T60 tectonic event and subsequent sedimentary environment researches. |
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