In the Arabian Sea (AS), higher organic matter preservation and biological productivity are observed during the summer due to strong southwest monsoonal winds. Centennial and millennial-scale fluctuation in the geochemical and relative abundance of foraminifera species are widely used to study the past preservation and productivity variation reconstruction in the Western Arabian Sea (WAS). The sediment records from the AS also show similarities with the North Atlantic and Greenland mainly during Heinrich events (HEs) which is related to the atmospheric and oceanic teleconnections of the AS with the higher latitude climate perturbations. In this context, we used a sediment core VM3504-PC from the WAS to understand the long-term changes in productivity and organic matter preservation using () relative abundance, total organic carbon (TOC) content, and calcium carbonate (CaCO) wt%. The TOC and shows a positive correlation, while significantly negative correlation is recorded in the TOC % and CaCO wt% datasets during interglacial periods (MIS5e-b, MIS3, and MIS1). Our results show evidence of CaCO dissolution and intense summer monsoon induced upwelling related productivity in core location during interglacial periods (MIS5e), based on higher relative abundance of (%), higher TOC content, and lower CaCO wt%. Interestingly, higher preservation of organic matter and increased productivity/nutrient concentration during mid-MIS4 suggesting stronger upwelling/winter convective mixing together with higher aeolian transport from adjacent landmasses. The abrupt weakening in the Atlantic Meridional Overturning Circulation (AMOC) synchronized with low productivity due to weak monsoon during HEs except for H6 and H4 in the tropical Indian Ocean. The H6 coincides with mid-MIS4 is showing abnormal preservation. Thus, AMOC and the summer monsoon significantly regulate primary productivity in the WAS. It is interesting to note that possibly well‑oxygenated deep-water masses do not penetrate up to surface water and/or ballistic effect (indicated by moderate sedimentation rate), preventing organic matter degradation on the seafloor during mid-MIS4.

中文翻译：

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MIS4（海因里希事件 6）中期阿拉伯海西部 AMOC 和季风突然增强

在阿拉伯海（AS），由于强劲的西南季风，夏季有机质保存和生物生产力较高。有孔虫物种地球化学和相对丰度的百年和千年尺度波动被广泛用于研究西阿拉伯海（WAS）过去的保存和生产力变化重建。 AS的沉积物记录也显示出与北大西洋和格陵兰岛的相似之处，主要是在海因里希事件（HEs）期间，这与AS的大气和海洋遥相关与高纬度气候扰动有关。在这种情况下，我们使用 WAS 的沉积岩芯 VM3504-PC 来了解生产力和有机质保存的长期变化，使用 () 相对丰度、总有机碳 (TOC) 含量和碳酸钙 (CaCO) wt% 。 TOC 和 表现出正相关，而间冰期的 TOC % 和 CaCO wt% 数据集中记录了显着的负相关（MIS5e-b、MIS3 和 MIS1）。我们的结果表明，基于较高的相对丰度 (%)、较高的 TOC 含量和较低的 CaCO wt%，CaCO 溶解和强烈的夏季季风导致间冰期核心位置 (MIS5e) 上升流相关的生产力。有趣的是，在 MIS4 中期，有机质保存率较高，生产力/养分浓度增加，表明上升流/冬季对流混合更强，以及来自邻近陆地的风输送更强。大西洋经向翻转环流（AMOC）的突然减弱与热带印度洋除 H6 和 H4 之外的 HE 期间由于季风较弱而造成的生产力低下同步。 H6 与 MIS4 中期一致，显示出异常保存。因此，AMOC 和夏季风显着调节了WAS 的初级生产力。有趣的是，可能充分氧化的深水团不会渗透到地表水和/或弹道效应（由中等沉降率表明），从而防止 MIS4 中期海底有机物降解。