Multiproxy data of pteropods and planktic foraminifera from Core SK291/GC17 suggest significant surface paleoceanographic shifts from ∼25,000 to 3500 calibrated years before present (cal yr BP) in the eastern Arabian Sea (EAS). Increased values of the global ice-volume free stable oxygen isotope ratio of seawater (δO IVF) and stable oxygen isotope ratio in pteropod (δO IVF), as well as lower percentages of planktic foraminifer from ∼22,000 to 18,000 cal yr BP, correspond to the weak Indian summer monsoon (ISM) during the Last Glacial Maximum (LGM). In the early Holocene, the EAS witnessed an increase in upwelling driven by strong summer monsoon winds, and a decrease in salinity corresponding with enhanced precipitation in the Western Ghats region. From ∼4800 to 4000 cal yr BP, including the 4.2 ka event, a prominent increase in the δO IVF values suggest an enhanced intrusion of the Arabian Sea High Saline Water (ASHSW) to the relatively deeper part of the mixed layer. In the same interval, the low representations of and thermocline dwelling planktic foraminifera indicate weakening of the coastal upwelling and a reduction in surface productivity due to weak ISM across the Arabian Sea, with more severe conditions in the EAS.

中文翻译：

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阿拉伯海东部从 25,000 到 3500 cal BP 的表面海洋学变化

来自核心 SK291/GC17 的翼足类和浮游有孔虫的多代理数据表明，东阿拉伯海 (EAS) 的地表古海洋学发生了显着的变化，从距今 25,000 年到 3500 年（cal BP）。全球海水游离冰量稳定氧同位素比值（δ18O IVF）和翼足类稳定氧同位素比值（δ18O IVF）的增加，以及浮游有孔虫百分比从约 22,000 到 18,000 cal yr BP 的降低，对应于末次盛冰期 (LGM) 期间印度夏季风 (ISM) 较弱。在全新世早期，东亚地区在强夏季季风的推动下上升流增加，而西高止地区降水增加导致盐度下降。从∼4800到4000cal yr BP，包括4.2 ka事件，δ18O IVF值显着增加表明阿拉伯海高盐水（ASHSW）对混合层相对较深部分的侵入增强。在同一区间内，温跃层浮游有孔虫的代表性较低，表明由于阿拉伯海 ISM 较弱，沿海上升流减弱，地表生产力下降，东亚地区的情况更为严峻。