Paleoceanography of the mid-Pleistocene South China Sea
Paleoceanography of the mid-Pleistocene South China Sea
复制标题
中更新世南海的古海洋学
DOI：
10.1016/j.quascirev.2008.02.007
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发表时间：
2008-06-01
影响因子：
4
通讯作者：
Chen, Muhong
中科院分区：
文献类型：
--
作者：
Li, Qianyu;Wang, Pinxian;Chen, Muhong
南海古环境指标的高频波动，包括稳定同位素和丰度的浮游有孔虫，超微化石，放射虫，和孢粉，揭示了一个动态的局部响应的逐步发展的中更新世气候转变（MPT）。这些代理人表明，在海表温度（SST）急剧下降约900 ka，在第四纪期间在该地区的第一个最大的SST下降。估计冬季SST在北方从24-25 ℃下降到17-18 ℃，在南海南部从26-27 ℃下降到23-24 ℃。随后的温跃层深度和动物区系-植物区系更替的变化意味着在MPT的最后阶段约300 ka的时期。冬季季风增加相似的900万年，并达到最大强度的MPT结束时，夏季季风也加强了间冰期。结果表明，南海北方与南部之间的温度梯度显著增大，北方冬季风影响增强，而南方则处于暖盐环境，尤其是冰期。这些南北向的古海洋学对比表明，大约在900 ka前，当南部的通道在冰川低水位期间开始完全暴露时，现代风格的半封闭南海开始建立。再加上深水冷却和通风，隆起的底床深度在巴士海峡，在这一时期造成了突然下降和灭绝的太平洋深水底栖有孔虫在孤立的深海盆地。再加上来自西太平洋海洋的数据，这些结果进一步表明，在MIS 23-22和随后的冰期，西太平洋暖池的相当大的削弱。虽然MPT可能引发了高纬度的过程，特别是增加冰量，热带过程更有可能促进恢复热量和能量的西太平洋在每一个间冰期反弹。浮游三角洲C-13最大偏心率周期导致重大冷却事件在第四纪表明全球碳库的变化，由于过去的气候变化中的低纬度和高纬度的过程中的重要作用。(C)2008爱思唯尔有限公司版权所有。
High-frequency fluctuations in paleoenvironmental proxies from the South China Sea, including stable isotopes and abundance of planktonic foraminifers, nannofossils, radiolarians, and palynomorphs, reveal a dynamic local response to the stepwise development of the mid-Pleistocene climate transition (MPT). These proxies indicate a dramatic drop in sea surface temperature (SST) at about 900 ka, the first largest SST decrease in the region during the Quaternary. Estimated winter SST declined from 24-25 degrees C to 17-18 degrees C in the northern and from 26-27 degrees C to 23-24 degrees C in the southern South China Sea. Subsequent changes in the thermocline depth and faunal-floral turnovers imply a period of about 300 ka in the final stage of the MPT. Winter monsoons increased at similar to 900 ka and reached a maximum strength toward the end of the MPT when summer monsoons also strengthened in interglacials. As a result, thermal gradient between the northern and southern South China Sea increased substantially, with stronger winter monsoon influence in the north and warm and saline conditions in the south especially during glacial periods. These N-S paleoceanographic contrasts indicate an initial establishment of the modern-styled semi-enclosed South China Sea about 900ka ago when passages in the south started to become completely exposed during glacial lowstands. Coupled with deep water cooling and ventilation, uplift of the sill depth in the Bashi Strait to near the present-2400 m during this period caused sudden decline and extinction of Pacific Deep Water benthic foraminifers in the isolated deep sea basin. Together with data from the oceanic western Pacific, these results further imply a considerable weakening of the western Pacific warm pool during MIS 23-22 and in subsequent glacial periods. While the MPT may have invoked high latitude processes especially an increased ice volume, tropical processes more likely have facilitated the restoration of heat and energy to the western Pacific in each interglacial rebound. Planktonic delta C-13 maxima on eccentricity periocities leading major cooling events during the Quaternary indicate the important role of global carbon reservoir changes due to low as well as high latitude processes in past climate change. (C) 2008 Elsevier Ltd. All rights reserved.