上新世以来轨道-亚轨道时间尺度上喜马拉雅山西部地区的风化剥蚀作用及其对印度夏季风的响应

The Indian (South Asian) summer monsoon is one of the most intense climatic phenomena on Earth. Its long-term development has been linked to the growth of high topography in South and Central Asia. The Arabian Sea is an ideal area for investigating tectonic-climatic interactions as well as the net impact of these processes on weathering and erosion of the western Himalaya, which plays a significant role in our understanding of regional and global climate change. However, the long-term and relatively high-resolution evolution history of the Indian summber monsoon remains rare. Based on the relatively continuous ~500 meters-long core sediments recovered from the Arabian Sea during the International Ocean Discovery Program Expedition 355 in 2015, together with the previously reconstructed high-quality age model, this study will carry out analyses on mass accumulate rate of detrital fractions with terrigenous origination, clay mineralogy, as well as elemental geochemistry and Sr-Nd isotopes of clay-sized detrital fractions with terrigenous origination, in order to quantitatively constrain terrigenous sediment provenances as well as weathering and erosional degrees of these terrigenous materials and thus to reconstruct the Indian summer monsoon intensity. Besides, the paleo-productivity as well as carbon cycle of the study area will be reconstructed by contents of organic materials as well as their carbon isotope. Combining comparison between the present results and typical geological/paleo-climatic factors such as tectonic activity, global paleo-temperature, and atmospheric CO2 concentration, we hope to probe into changes of the Indian summer monsoon in the study area at sub-orbital to orbital timescales since the Pliocene, its driving mechanism, as well as its significance for sediment source-to-sink process, paleo-productivity, and carbon cycle.

作为全球最强的气候现象之一，印度（南亚）夏季风的长期演化被认为与南亚和中亚高地形的发育密切相关。阿拉伯海是研究上述构造-气候相互作用及其喜马拉雅山西部地区风化剥蚀效应的理想靶区，对认识区域乃至全球气候变化有重要科学意义，但印度夏季风的长期、较高分辨率演化记录迄今仍很少见。本项目利用国际大洋发现计划IODP 355航次于2015年在阿拉伯海钻取的、沉积总体连续的约500米长岩芯，基于前期建立的高质量年代框架，通过陆源碎屑态沉积通量、粘土矿物、粘土粒级硅酸盐组分元素和Sr-Nd同位素来定量识别大陆物质贡献及其风化剥蚀程度进而反演印度夏季风强度，根据有机质含量及其碳同位素来反演古生产力水平及碳循环过程，再结合与造山运动、全球古温度及大气二氧化碳含量等特征地质/古气候信号间对比，探索上新世以来研究区轨道-亚轨道时间尺度上印度夏季风演化过程、驱动机制及其沉积物源-汇过程、古生产力和碳循环效应。

作为全球最强的气候现象之一，南亚（印度）夏季风的长期演化被认为与南亚和中亚高地形的发育密切相关。阿拉伯海是研究上述构造-气候相互作用及其喜马拉雅山西部地区风化剥蚀效应的理想靶区，对认识区域乃至全球气候变化有重要科学意义，但南亚夏季风的长期、较高分辨率演化记录迄今仍很少见。本项目利用国际大洋发现计划IODP 355航次于2015年在阿拉伯海钻取的、沉积总体连续的约500米长岩芯，基于前期建立的高质量年代框架，通过陆源碎屑态沉积通量、粘土矿物、粘土粒级硅酸盐组分元素和粘土粒级硅酸盐组分Sr-Nd同位素来定量识别了大陆物质贡献及其风化剥蚀程度进而反演了南亚夏季风强度，根据有机质含量及其组成特征来反演了古生产力水平及碳循环过程，再结合与造山运动、全球古温度及大气二氧化碳含量等特征地质/古气候信号间对比，探索了上新世以来研究区构造、轨道、亚轨道乃至千年时间尺度上南亚夏季风的演化过程、驱动机制及其沉积物源-汇过程、古生产力和碳循环效应。据初步估计，第四纪冰期低海平面时期的阿拉伯海及孟加拉湾地区很可能在全球有机碳循环中发挥着非常关键的作用（当前全球海洋中总埋藏量的~1/4）。