Formation of Hydroxy-Interlayered Smectites (HIS) as an evidence for Paleoclimatic Changes along the Riverine Sediments of Pravara Rivers, Maharashtra

Clay minerals from a riverine badland sediments along the banks of Pravara Rivers and two of its main tributaries Adula and Mahalungi have been studied to understand sedimentological environments of these deposits. The main clay minerals for all the samples are identical and show the presence of hydroxy-interlayer smectites with minor quantities of mica, kaolin, smectite, quartz and feldspar. The first weathering product of the Deccan Basalt (DB) is the dioctahedral smectite. The present semi aridic climatic condition of the study area can not transform a smectite to HIS and also smectite to kaolin. It is quite likely that both the HIS and Sm/K are generated in the tropical humid climate of the Western Ghats and then carried through the exiting river system like Godavari, Adula and Mahalungi. Therefore it is evident that the clay minerals present in these sediments represent another climatic history more humid than the one existing at present.