Tracking the Millennial Scale Variability of Deep Water Circulation and Lithogenic Influence in the Arabian Sea Over the Past 41 ka Through Nd Isotope

Abstract This study reconstructs the past variability of deep‐water masses in the Arabian Sea, predominantly influenced by North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW). We present a high‐resolution (∼400 years) authigenic Nd isotope record from the Eastern Arabian Sea (SSD60‐GC10; 2,055 m), complemented by detrital Ɛ Nd data, to investigate millennial‐scale circulation changes and the influence of lithogenic inputs on seawater Nd isotopes over the past ∼41 ka. Seawater Ɛ Nd record range from −10.8 to −6.6, with more radiogenic signatures during cold events (HS 1 to 4, Last Glacial Maximum (LGM), Younger Dryas, and 4.2 ka), whereas less radiogenic signatures characterize warm periods (early deglacial and Bølling‐Allerød). Results suggest dominance of AABW during ∼41–28 ka, and enhanced contribution of NADW throughout the Holocene. Reduced NADW during cold periods likely weakened the Atlantic Meridional Overturning Circulation, resulting in a southward shift of the Intertropical Convergence Zone, which suppressed the Indian summer monsoon. Conversely, enhanced NADW during warm periods strengthened monsoon intensity. A comparison between Indian and Atlantic Ocean records suggests that the alteration of Nd isotope signatures of the water masses (low Ɛ Nd ) in the Arabian Sea occurred between ∼28 and 18 ka due to detrital lithogenic input. This provides new evidence of lithogenic Nd input from the Ganga‐Brahmaputra‐Peninsular rivers, influencing Ɛ Nd values of the Arabian seawater during the last glacial periods with limited influence beyond this interval. Authigenic Ɛ Nd record primarily reflects NADW‐AABW variability. High sedimentation rates during LGM enabled reconstruction of high‐frequency Nd isotope record, highlighting millennial‐scale deep‐water variability linked to centennial‐millennial‐scale climate fluctuations at high latitudes.