Provenance Studies of Ilmenite from Red Sediments, Bhimunipatnam Coast, East Coast of India

Abstract

Mineral chemistry of the ilmenites, drawn from the red sediments along the Bhimunipatnam coast, Andhra Pradesh, India was determined by EPMA technique. The major constituents are TiO2 and FeO, and the value of Ti/(Ti + Fe) < 0.5 of these ilmenites indicate that they are relatively fresh ‘ferrian ilmenites’ and were contributed recently to the red sediments in the study area. Using the mineral chemical data, the end-member composition of the analyzed ilmenites was calculated, which reveals that they are of ‘ilmenite - hematite’ and ‘ilmenite - geikielite - hematite’ composition, derived from calc-alkaline magma-sourced charnockites and metapelitic khondalite suite of rocks respectively of the Eastern Ghats granulite belt. The TiO2 content and Mn/Mg ratio of the study ilmenites indicate that these rocks constitute their provenance in the Gosthani river basin. Their back scattered electron (BSE) and scanning electron (SEM) images show their prominent sub-angular to sub-rounded shape, corroborating the study under microscope, with some preserving signatures of exsolution intergrowth, earlier deformation and rounded shape, all of which are attributed to their transportation by the Gosthani river, after their liberation from their provenance rocks.