Pollen based inference of Holocene sea level changes, depositional environment and climatic history of Cauvery delta, Southern India
Résumé
Palynological and other sedimentary records in the south-eastern peninsular India where the retreating (North-East) monsoon brings the main rainfall are scarce. This paper tries to address not only this gap in data but also the methodological challenges of interpreting such data in terms of sea level, depositional environment and climatic changes of the area going back nearly 11040 years. In addition to other (chemical) proxies studied previously, pollen data of a chronologically well constrained sediment core (~20 m) from Porayar (11°01.178′N 79°50.446′E), in the coastal marginal part of the Cauvery delta, Southern India, have been analyzed. The three major pollen zones observed since 11,040 years are presented and discussed, as are the methodological challenges of interpreting the vegetation record in such a dynamic and diverse environment (the delta plains of southern India). The zones observed indicate various transitions: from a lower sea level condition to a more stable sea level that created an estuarine environment filled with brackish water that supported pollen assemblages of a marshland but not a true mangrove. Concurrently, pollen assemblages that indicate catchments at multiple spatial scales – local to regional, extending from the North-East monsoon dominated delta to the Western Ghats is also inferred for climate interpretation.