Genesis of kaolin deposits of Birbhum, West Bengal, India

Abstract

The mineral phases and the distribution of major, minor and trace elements in the clays and bed rocks of two bore-holes at Adda and Chaubatta of the Birbhum area have revealed an intimate relationship of the kaolin-rich clays with the bed-rock of Adda. The possibility of a common origin for the clay deposits at Chaubatta, lying close to the Rajmahal trap formations, and at Adda, lying close to the Archaean boundary, has been inferred from trace element distribution and other factors. A genetic relationship of the clay deposit at Adda with the bed-rock, altered Archaean gneiss, has been established, but there is no significant relationship of the Chaubatta clay deposit with its bed-rock, the weathered basalt.The lateritic cappings above the kaolin-rich clays of Adda and Chaubatta areas are explained as being formed from kaolinite in the weathering sequence as the end-product of intensive desilication under conditions of intensive leaching and increasing acidity near the surface.