Distribution of minor elements in the shelf and deep sea sediments of the northern Arabian Sea

Abstract

Results on the distribution of minor elements (Cu, Ni, Cr, Co, Pb and V) in the surficial sediments of the northern Arabian Sea (latitude 15–20°N, longitude 65–73°30′E) are presented. Based on the texture of the sediments and the distribution of clay minerals, the study area is divided into three regions: (1) the inner shelf, of silty-clay enriched with montmorillonite; (2) the outer shelf, dominated by sand and illite; and (3) the deep sea, consisting of clayey silt. Except for Pb, all elements showed relative enrichment in the inner shelf and deep sea when compared with outer-shelf sediments, in accordance with their texture and grain size parameters. Metal/Al ratios indicate their occurrences in both lithogenous and non-lithogenous fractions. Most of these elements are detrital in origin and are primarily present in montmorillonite, illite, amphiboles, pyroxenes, garnets, feldspars and ilmnite. Adsorption on FeMn oxides and incorporation in authigenic minerals, such as anatase, are the other possible sources of these trace elements in the sediments.