Rock to Regolith: A Synthesis of Physico-chemical Processes in Purulia District, West Bengal

Abstract

The present study is trying to identify the existing nature and processes of weathering and regolith development in the studied weathering profile in Raghunathpur-I block, Purulia district, West Bengal. The thin section analysis of collected samples has been carried out for mineral identification and recognizing micro-fractures and their propagation. The major elemental composition in the samples from different weathering grades has been measured by XRF technique. The open-system mass change ( j,w ) and CIA have been calculated for understanding mineralogical transformations and the degree of weathering respectively. The result shows that quartz, feldspar, and micas composed granitic bedrock is gradually fragmented and altered into Fe-oxides and secondary clay by progressive microfractures development and hydro-chemical weathering. But the chemical analysis of major elements indicates poor depletion of SiO2 than other elements (Si, Al, Fe, Na and K) which denote the lower degree of transformation of quartz and silicate minerals. Therefore, the potentiality for both physico-chemical weathering is recognized to develop more mature regolith