...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Paleoceanography >Geochemical record of chemical weathering and monsoon climate change since the early Miocene in the South China Sea
【24h】

Geochemical record of chemical weathering and monsoon climate change since the early Miocene in the South China Sea

机译：自南海中新世早期以来化学风化和季风气候变化的地球化学记录

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The chemical index of alteration (CIA) and elemental ratios that are sensitive to chemical weathering, such as Ca/Ti, Na/Ti, Al/Ti, Al/Na, Al/K, and La/Sm, were analyzed for detrital sediments at Ocean Drilling Program Site 1148 from the northern South China Sea to reveal information of chemical weathering in the source regions during the early Miocene. High CIA values of similar to 80, coupled with high AIM and Al/Na and low Na/Ti and Ca/Ti, are observed for the sediments at similar to 23 Ma, indicating a high chemical weathering intensity in the north source region, i.e., south China. This was followed by gradual decreases in AIM, Al/Na, La/Sm, and Al/K ratios, as well as the CIA values, and increases in Ca/Ti and Na/Ti ratios. These records together with other paleoclimate proxies, such as black carbon delta C-13 and benthic foraminifer delta O-18, give reliable information on the climate changes in south China. Our results show that the climate in south China was warm and humid in the early Miocene (similar to 23 Ma) according to the chemical weathering records. The humidity in south China decreased from the early Miocene to Present with several fluctuations centering at approximately 15.7 Ma, 8.4 Ma, and 2.5 Ma, coincident with the global cooling since the middle Miocene. These climate changes implied that the summer east Asian monsoon has dramatically affected south China in the early Miocene, whereas the influence of the summer monsoon on this region has decreased continuously since that time, probably because of the intensification of the winter monsoon. Such an evolution for the east Asian monsoon is different from that for the Indian monsoon.
机译：分析了对化学风化敏感的化学变化指数（CIA）和元素比，例如碎屑沉积物的Ca / Ti，Na / Ti，Al / Ti，Al / Na，Al / K和La / Sm。在南海北部的海洋钻井计划站点1148上，揭示了中新世初期源区化学风化的信息。在类似于23 Ma的沉积物中，观察到的CIA值接近80，同时具有较高的AIM和Al / Na以及较低的Na / Ti和Ca / Ti，表明北部源区的化学风化强度较高，即，华南。随后，AIM，Al / Na，La / Sm和Al / K比以及CIA值逐渐降低，而Ca / Ti和Na / Ti比则增加。这些记录以及其他古气候代理，如黑碳三角洲C-13和底栖有孔虫三角洲O-18，为中国南方的气候变化提供了可靠的信息。我们的结果表明，根据化学风化记录，中新世早期（类似于23 Ma）华南的气候温暖潮湿。华南地区的湿度从中新世早期到现在下降，集中在大约15.7 Ma，8.4 Ma和2.5 Ma上出现了几次波动，这与中新世以来的全球降温相吻合。这些气候变化表明，夏季的东亚季风在中新世早期严重影响了华南地区，而自那时以来，夏季风对该地区的影响一直在持续下降，这可能是由于冬季风的加剧。东亚季风的这种变化与印度季风的变化不同。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号