Significance of the Paralia sulcata fossil record in palaeoenvironmental reconstructions of the SE Asia marginal seas over the Last Glacial Cycle

Abstract

AbstractParalia sulcata (Ehr.) Cleve, a common diatom microfossil species in shelf and adjacent deep-sea sediments, is becoming potentially useful in palaeoenvironmental reconstructions due to its coarsely silicified exoskeleton being well preserved in sediments. This paper presents the distributions of P. sulcata in sediment cores from the SE Asian marginal seas taken from formerly published and original materials. Paralia sulcata achieved variable abundance in the glacial–interglacial sediment analysed, showing spatial changes in the core profiles of the South China Sea, with lower abundances during the last glacial stage and higher values in the post-glacial. Conversely, in the East China Sea, it attains lower abundances during the Holocene, while higher ones in last glacial stage. Over a short timescale, variations in the abundance of this species responded quickly to the climatic and oceanographic fluctuations. We illustrate a ‘seesaw’ effect that its high abundances revealed in the East China Sea at 15–11 cal ka BP, whereas this occurred during period 11–8 cal ka BP in the South China Sea. The rapid increase in abundance of this species in the South China Sea is interpreted as an indication of a plausible link with the opening of the Taiwan Strait and the general coastal water circulation pattern during deglaciation.