Hydroclimatic conditions and sediment provenance in the northeastern Arabian Sea since the late Miocene: insights from geochemical and environmental magnetic records at IODP Site U1457 of the Laxmi Basin

Abstract

Palaeo-monsoon and palaeoclimate conditions over Southeast Asia are a matter of debate despite notable studies on the continental and oceanic sedimentary record. The present study investigates the environmental magnetic and geochemical records preserved in the deep marine sediments of the northeastern (NE) Arabian Sea to elucidate the erosion history of the western Himalayas and its link with the prevailing hydroclimatic conditions since the late Miocene. For this, the sediment core retrieved during International Ocean Discovery Program (IODP) Expedition 355 at Site U1457 in the NE Arabian Sea has been explored. The results reveal that the hydroclimatic conditions were predominantly arid during the late Miocene, except for humid intervals from 6.1 Ma to 5.6 Ma. Humid climate conditions in the Indus River Basin returned during the mid-Pliocene and continued to the Pleistocene with an intense chemical weathering regime from 1.9 Ma to 1.2 Ma. The dominant sediment source to the NE Arabian Sea at Site U1457 during the late Miocene and the Pliocene was the Indus River, while during the Pleistocene, mixed sediments brought by the Indus River and the Peninsular Indian rivers were observed. The sediment contribution from a chemically less altered mafic source (the Deccan basalts) increased between 1.2 Ma and 0.2 Ma, possibly linked to a weak Indian Summer Monsoon. The summer monsoon wind strength and associated shift in the Inter-Tropical Convergence Zone (ITCZ) influenced the dominant sediment provenance at Site U1457 of the Laxmi Basin.

Geochemical Split Among the Suspended and Mud Sediments in the Nethravati River: Insights to Compositional Similarity of Peninsular Gneiss and the Deccan Basalt Derived Sediments, and Its Implications on Tracing the Provenance in the Indian Ocean

“…Many geochemical studies from the Indian Ocean report the sediment provenance and erosion history in the subcontinental region. Most of these geochemical studies inferred that sediments are dominantly contributed by the Himalayas with a subordinate contribution from the Deccan Province (Acharya & Chakrabarti, 2019; Alam et al., 2023; Avinash et al., 2016; Goswami et al., 2012; Kessarkar et al., 2003; V. P. Rao et al., 2015). Most of these studies overlook the contribution of Peninsular Rivers to the sedimentary budget of the Indian Ocean.…”

“…However, tracking the sediments from TTG, SGP, and DB from peninsular India is important (a) to unravel the geological history of Peninsular India and the Deccan Province, and (b) to understand the paleoclimate and paleomonsoon in the sub‐continental region. In the literature, there are limited studies focused on tracking the sediment provenance from the felsic lithologies of Peninsular India to marginal sedimentary basins (Acharya & Chakrabarti, 2019; Kessarkar et al., 2003; Kurian et al., 2013; Nair et al., 1982; V. P. Rao & Rao, 1995) and most of the available studies successfully decipher the sediment provenance between the Himalayas and the DB (Alam et al., 2023; Clift et al., 2019; Khim et al., 2020). In the Arabian Sea, most of the geochemical and mineralogical studies consider the sediment contribution from the TTG and SGP as minor and often attribute mafic sediment components as input from the Deccan Province.…”