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Climate and sea level forcing of terrigenous sediments input to the eastern Arabian Sea since the last glacial period.
- Source :
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Marine Geology . Aug2022, Vol. 450, pN.PAG-N.PAG. 1p. - Publication Year :
- 2022
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Abstract
- Analyses of mass accumulation rate (MAR), laser grain-size, clay mineralogy, and Sr Nd isotopic compositions of <2 μm and < 63 μm grain-size fractions have been applied to sediments from the International Ocean Discovery Program (IODP) Site U1456, which span the last 31 ka, in order to constrain (i) past changes in the relative proportions of the fine-grained detrital sediments derived from the Indus River and the Deccan Traps and the dynamics of sediment transport to the Laxmi Basin and (ii) past changes in Indian monsoon rainfall and latitudinal migration of Intertropical Convergence Zone since the last glacial period. Sr and Nd isotopes results combined with clay mineral assemblages suggest that clay-sized sediments at IODP Site U1456 derive mainly from the Indus River (70–90%), followed by a minor contribution from rivers draining the volcanic province of the Deccan Traps (10–30%). During the Last Glacial Maximum, clay mineralogy was dominated by illite and chlorite primarily derived from the highlands of the Indus River basin. The combination of lower temperatures and lower monsoonal rainfall during glacial times led to a reduction of smectite formation rates in the floodplains, while glacial erosion accelerated in the Himalayan and Tibetan highlands leading to the release of large quantities of illite and chlorite minerals into the Arabian Sea. In addition, glacial low sea-level stands allowed a connection between river mouths and the heads of deep-sea channels favoring the southward transfer of sediments to IODP Site U1456 by turbidity currents. Each maximum of the summer insolation curve, associated with a northward shift of the ITCZ and an intensification of summer monsoon rainfall (from 31 to 25 ka BP and from 12 to 8 cal ka BP), was associated with enhanced rainfall in the Indus floodplain which in turn led to an increase in the physical erosion and weathering of plain soils, which were rich in pedogenic minerals (such as smectite), and/or a higher production rate of smectite in the soils of the Indus floodplain. A compilation of three Nd isotopic composition records obtained at sites located on a N-S latitudinal transect in the eastern Arabian Sea have allowed us to establish the impact of sea level variations and latitudinal migration of the ITCZ over time on the sedimentation of the eastern Arabian Sea. • The detrital sediments in the eastern Arabian Sea are mainly sourced from the Indus River and Deccan Traps since 31 cal ka BP. • The climate and sea-level variations forcing of detrital sediments input to the eastern Arabian Sea since 31 cal ka BP. • The shift in river inputs between N-S could be related to a migration of the ITCZ and associated location of the rain belt. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00253227
- Volume :
- 450
- Database :
- Academic Search Index
- Journal :
- Marine Geology
- Publication Type :
- Academic Journal
- Accession number :
- 158117147
- Full Text :
- https://doi.org/10.1016/j.margeo.2022.106860