Palaeoclimatic Significance of Gypsum Pseudomorphs in the Inner Shelf Sediments Off Machalipatnam Bay

Abstract

Pseudo-gypsum crystals have been found in the coarse fraction of the sediments from the inner continental shelf off Machalipatnam Bay. They range in size from 3 to 7 mm and are elongate arid lenticular in shape. Bassanite and calcite are pseudomorphs after gypsum. The origin of the pseudo-gypsum has been discussed and it is suggested that these are indicators of late Pleistocene climatic aridity. The bay sediments deposited during late Pleistocene were subsequently eroded by waves and currents due to sea level changes and the coarse fraction of the sediments containing pseudogypsum were transported and deposited in the inner continental shelf.