Palynology and Depositional Environment of Fossiliferous Clays from Goa State

Occurrence of fossiliferous clay beds underlying the laterite cap and containing palynofossils has been recorded from Goa State. The first occurrence is from the north bank of Mandovi river at the bridge on Mapusa-Panaji road where bluish grey clay yielded spores. The second occurrence is from the Iron Ore Mine of M/S Lithoferro Pvt. Ltd. at Village Sangod, South Goa. It exposes carbonaceous clay containing carbonized plant debris. Palynoassemblage, comprising elements such as Ceiba sp., Cocos nucifera, palm sp., Lycopodium inundata, Lygodium fiexuosum, Ceratopteris thalictroides, Ceratopteris sp. etc., along with microforaminiferal organic linings indicates estuarine environment of deposition and the climate to be tropical and humid with high rainfall. Further, presence of marcasite in these clays associated with strong sulphurous odour also points out their deposition under reducing condition. On the basis of the mode of occurrence and palynoassemblage, these clays correspond to the Ratnagiri Beds exposed in Ratnagiri and Sindhudurg Districts of Maharashtra State, suggesting that the clay beds of Goa are the southward extension of Ratnagiri Beds. Neotectonic activity is reflected by the uplift of estuarine sediments above the prcsent sea level as well as the deeply entrenched and highly meandering river courses in the study area.