Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao, China.
Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Nat Commun. 2023 Feb 14;14(1):829. doi: 10.1038/s41467-023-36537-6.
The evolution and driving mechanism of the South Asian summer monsoon (SASM) are still poorly understood. We here present a 12-Myr long SASM record by analyzing the strontium and neodymium isotopic composition of detrital components at IODP Exp. 359 Site U1467 from the northern Indian Ocean. The provenance investigation demonstrates that more dust enriched in εNd from northeastern Africa and the Arabian Peninsula was transported to the study site by monsoonal and Shamal winds during the summer monsoon season. A two-step weakening of the SASM wind since ~12 Ma is proposed based on the εNd record. This observational phenomenon is supported by climate modeling results, demonstrating that the SASM evolution was mainly controlled by variations in the gradient between the Mascarene High and the Indian Low, associated with meridional shifts of the Hadley Cell and the Intertropical Convergence Zone, which were caused by interhemispheric ice-sheet growth since the Middle Miocene.
南亚夏季风（SASM）的演化和驱动机制仍未被很好地理解。我们通过分析印度洋 IODP 勘探 359 号站 U1467 处碎屑成分的锶和钕同位素组成，得到了一段长达 1200 万年的 SASM 记录。物源研究表明，在夏季季风季节，更多来自东北非和阿拉伯半岛、富含 εNd 的尘埃被季风和沙玛尔风带到研究地点。基于 εNd 记录，我们提出了自约 1200 万年前以来，SASM 风的两步式减弱。这一观测现象得到了气候建模结果的支持，表明 SASM 的演化主要受马斯克林高压和印度低压之间梯度变化的控制，这与 Hadley 细胞和热带辐合带的经向移动有关，而这是从中新世中期以来半球间冰盖增长引起的。
