Studies on Holocene climatic changes from Priyadarshini Lake sediments, East Antarctica: The palynological evidence

Abstract

Pollen analysis of a sediment core from Priyadarshini Lake (Core S3), East Antarctica, has revealed the climatic oscillations in the region since Holocene. Three pollen zones have been identified on the basis of recovered pollen taxa and varying frequencies. Between 10,000 and 9,000 yr BP, cold and dry climate prevailed in the region as reflected by the dominance of grasses, Acritarch and very low frequencies of Cosmarium - a fresh water alga. The lake was probably shallow and smaller in dimension during this period. Between 9,000 to 2,400 yr BP, relative increase in grasses is witnessed though in fluctuating frequencies. Cosmarium also exhibits a distinct increasing trend, whereas Acritarch declines considerably. This overall change in the assemblage reflects the onset of warm and moist climate and the lake had a wider expansion during this phase on account of amelioration in climate than witnessed before. Between 2,400 and 1,000 yr BP, relatively reduced frequencies of grasses, coupled with total disappearance of Cosmarium, demonstrate that the climate changed once again to cold and dry. However, 1,000 yr BP onwards, marked increase in grasses coupled with exceedingly high values of Cosmarium implies that the climate ultimately turned warm and moist.