Textural attributes of Sandstones from extra-peninsular Kalijhora Gondwana Basin in Darjeeling District, West Bengal, India

Extra-peninsular Gondwana rocks are exposed in and around Kalijhora in Darjeeling district of West Bengal. The Kalijhora lithostratigraphic column is largely arenaceous. An attempt was made to analyse the textural attributes of these Gondwana sandstones which was unknown till date. Kalijhora sandstones are largely medium grained, poorly sorted, positively skewed and leptokurtic. The main mode of transportation for the sandstones seems to be combination of traction and suspension mechanism. Mixing of finer grains imparted bimodality to the distribution. Addition of fines to the relatively coarser main mode suggests the occurrence of a temporary turbid like condition in the otherwise calm riverine depositional environment leading to the transport of both coarser and finer fragments side by side. A phase of transgression also affected the sediments that show affinity towards deltaic (fluvial) as well as shallow marine depositional setting.