Petrology and geochemistry of the Late Archaean siliceous high-magnesian basalts (SHMB) from Kaklur, Southern Bastar craton, Central India

Abstract

Greenschist facies metabasalts showing relict spinifex texture, associated with the Late Archaean Bengpal Group, are well exposed in the Kaklur area, Bastar craton, They are classified as siliceous high-magnesian basalts (SHMB) on the basis of its distinct chemistry, such as high SiO₂ (52.83-54.52 Wt%), high MgO (11.40-18.35wt%),high Cr, Ni, enriched Rb and K, depleted Nb and Ti, and enriched-LREE as well as the presence of spinifex texture. Low Al₂O₃/Tio₂ and Sc/Y ratios, high Ti/Zr and Sr/Nd ratios less than the chondrite corroborate SHMB nature of these basalts and clearly distinguishes them from komatiites/komatiitic basalts and boninites, They show close geoechemical similarities particularly in high field strength and rare earth element concentrations. with other well studied Western Australian SHMB. Such SHMB are reported in literature to be derived either from komatiitic magma by crustal contamination through assimilation -fractional crystallization (AFC) processes or from magma generated from the refractory continental lithosphere.