Trace Elements and Sr, Nd Isotope Compositions of Surface Sediments in the Indian Ocean: An Evaluation of Sources and Processes for Sediment Transport and Dispersal

Abstract

To decipher sediment provenance, understand dispersal pattern and its controlling factors in the Indian Ocean, we have studied major and trace element abundances and isotope compositions of Sr (87Sr/86Sr) and Nd (εNd) in silicate fractions of 38 surface sediment samples collected at ~1.5° interval from India (~10°N) to Antarctica (~70°S). The 87Sr/86Sr ratio and εNd vary from 0.70527 and 0.1 near Crozet Island to 0.77854 and −34.8 near Antarctica, respectively. Higher 87Sr/86Sr ratio and lower εNd near Antarctica indicate source of old granitic rocks, and the opposite is observed in sediments from the Central and the Southwest Indian Ridges indicating source of seafloor spreading and mid‐ocean ridge hydrothermal activity. Chondrite normalized Rare Earth Elements (REEs) pattern reveals positive Europium anomaly for Central and Southwest Indian Ridge sediments, while positive Gadolinium anomaly is observed in Indian and Antarctic coastal sediments. Sediments in the Indian sector of Southern Ocean and coastal Antarctica are highly dispersed through deep, bottom, and Antarctic circumpolar currents. The εNd spatial map generated for the entire Indian Ocean based on compilation of present study and results from literature shows dominance of terrigenous inputs from continental erosion with minor contribution from the ridges in the Indian Ocean. The εNd map together with trace elements can be employed for reconnaissance for mineral exploration associated with hydrothermal deposits. Further, comparison of detrital εNd with its counter phases, that is, authigenic fractions and modern seawater at the sampling sites, would enhance our knowledge of benthic exchange processes, with an implication in using Nd isotopes as a water mass circulation proxy.

Fractionation Trends and Variability of Rare Earth Elements and Selected Critical Metals in Pelagic Sediment from Abyssal Basin of NE Pacific (Clarion-Clipperton Fracture Zone)

“…Oliver and Boyet [89] suggested that Ce an , as well as the enrichment of HREE relative to LREE, could be masked due to elevated contents of terrigenous material. This situation is particularly true, as regards the clay minerals and fine grain quartz, often depleted together with REE [90,91]. Bau and Dulski [92] proposed a binary diagram, which provides a test of whether the calculated negative Ce an was real, or masked by positive La an (Figure 20).…”

Rift‐related multistage evolution of the Mangalwar Complex, Aravalli Craton (NW India): Evidence from elemental and Sr–Nd isotopic features of Proterozoic amphibolites

“…Sr and REEs followed by Nd were separated from the dissolved samples using the columns that contain AG 50W‐X8 (200–400 μm) resin and Eichrom LNspecTM (50–100 μm) resin respectively. Detailed column separation procedure has been discussed elsewhere (Giri et al, 2021; W. Rahaman, Singh, Sinha, & Tandon, 2009; Samal, Srivastava, & Rahaman, 2021; Subha Anand et al, 2019).…”

“…Detailed column separation procedure has been discussed elsewhere (Giri et al, 2021;W. Rahaman, Singh, Sinha, & Tandon, 2009;Samal, Srivastava, & Rahaman, 2021;Subha Anand et al, 2019).…”

Control of oceanic circulation on sediment distribution in the southwestern Atlantic margin (23 to 55° S)

“…Concerning deep circulation, the North Atlantic Deep Water (NADW) (Sverdrup et al, 1942), transported from the Northern Hemisphere high latitudes by the Deep Western Boundary Current, occupies the region between the 2000 and 3000 m isobaths. The NADW flows between two northwardflowing branches of the Circumpolar Water (i.e., Upper and Lower Circumpolar Deep Water).…”