Chemical weathering patterns driven by solar insolation and Indian monsoon in the southern Bay of Bengal since the last glaciation.

[Display omitted] • Sediments in the southern Bay of Bengal mainly sourced from terrestrial materials transported by inflow rivers. • Multiple rivers dominated the glacial sediment provenance, whereas Indian peninsula materials increased during the Holocene. • Chemical weathering on glacial-interglacial scales was controlled by solar insolation. • Millennial variations of chemical weathering matched well with the Indian monsoon system. Chemical weathering has a significant role in controlling sediments production and transport, both of which are closely linked to environmental conditions and climate change. This study examines BoB-79, a core located in the southern part of the Bay of Bengal (BoB), to investigate the chemical weathering of terrestrial materials since the last glacial period in the Indian Ocean. Multiple geochemical proxies were employed to reconstruct the weathering history and to establish links with global and local environmental shifts. Analysis of rare earth element (REE) indices pinpointed terrestrial materials as the main sediments provenance in the southern BoB. During the last glacial stage, the sediments in core BoB-79 were sourced from multiple rivers surrounding the BoB; these deltaic systems prograded, leading to a mixture of sediments being transported to the southern BoB. Conversely, during the Holocene stage, the sedimentary signature from core BoB-79 more closely resembled that of the Krishna-Godavari rivers, indicating an increased terrestrial supply from the Indian Peninsula. Collectively, TiO 2 , the chemical index of alteration (CIA), αAlNa, and the illite chemical index were observed to align with changes in solar radiation intensity in the northern hemisphere. Millennium-scale fluctuations might be attributed to global climate events such as Heinrich 1 (H1), Younger Dryas (YD), and Bølling/Allerød (B/A) through the Indian monsoon system. Thus, investigation into the chemical weathering process and its reaction to changes of solar insolation and the Indian monsoon provide compelling evidence for understanding air-sea interactions in the southern BoB since the last glaciation. [ABSTRACT FROM AUTHOR]