Distribution and paleoecologic efficacy of microforaminiferal organic linings from deep sea Quaternary sediments off Vishakhapatnam coast

Abstract

246-250Good population of microforaminiferal organic linings received during the palynological studies of deep sea quaternary sediments off Vishakhapatnam coast, are classified under 7 morphotypes (3 planispiral types and 2 each of trochospiral and uniserial types). Qualitative and quantitative distribution of these linings are reasonably consistent with corresponding continentality ratio (i.e. relative abundance of continental pollen/spore influx and marine dinocysts) and total organic matter (TOM), reflecting two contrasting climatic events. Significant decrease in lining population and corresponding rise in continentality ratio for middle part of the lowermost pollen zone (P-III), show major climatic amelioration possibly of the last pre-glacial period. Whereas the sediment interval of P-I zone (approximately 58 to 100 cm depth in core GC 87 and 25 to 48 cm depth in core GC 96) documenting prominently rich lining population and minimal continentality ratio, represents the last glacial maximum (LGM) interval of 18000 yBP. Ecologically, the decreasing population trend is inferred as climatic warming and hence the reduction in salinity. On other hand, the increase in lining population is referred to cooling climatic trend, resulted in relatively higher salinity