Chemistry of surface sediment along a north–south transect across the equator in the Central Indian Basin: an assessment of biogenic and detrital influences on elemental burial on the seafloor

• Published in: Chemical geology 1998-05, Vol.147 (3), p.217-232
• Main Authors: Banakar, V.K, Parthiban, G, Pattan, J.N, Jauhari, P
• Format: Article
• Language: English
• Subjects: Biogenic-Al; Elemental-Ba; Equatorial Indian Ocean; Geochemistry; India, Central Indian Basin; Productivity; Sediment
• ISSN: 0009-2541; 1872-6836
• DOI: 10.1016/S0009-2541(98)00015-1

Nineteen surface sediment samples collected along a north–south transect across the equator in the Central Indian Basin (CIB) were analysed for their major, minor, and rare earth element (REE) composition. In absence of the element-flux data, we demonstrate here the association of various elements and their preferential sinks using inter-elemental associations in sediment exhibiting latitudinal dissimilarity. Biogenic sedimentation north of the equator (1° to 4°N latitudes) is dominated by carbonate ooze, whereas south of the equator (4° to 14°S latitudes) is dominated by siliceous ooze. Carbonate ooze deposition (>60% CaCO 3) above 4400 m and its drastic reduction (to 80% of their respective total content in all the three sediment zones. These observations suggest a close link between Ba and a Mn-oxide phase. On the other hand, nearly overlapping latitudinal trends of Al XS with carbonate in areas north of the equator and opal south of the equator; strong positive correlation of Al XS with opal ( r=+∼0.8), similar ratios between carbonate-free opal and Al XS (∼16) in both biogenic sediments suggest a close link between productivity and Al XS. The Al XS proportion in both biogenic sediment types is around 28% of the total Al suggesting nearly the same level