Vegetation and environmental record in the northern East China Sea during the late Pleistocene

摘要

In order to understand fluctuations in terrestrial and marine environments influenced by the East Asian Monsoon during the last 42 kyr, we investigated a sedimentary core MD982195 collected from the northern East China Sea (ECS), one of the largest marginal seas in the world. The total abundance of pollen and spores varies from 4.8 to 22.3 x 10~3 grains g~(-1). The pollen and spores can be grouped to represent six local zones of pollen assemblage based on their abundance and assemblages. Pollen assemblage found in the modern condition (zone MD2195-6) is consistent with the present vegetation found in Kyushu, Japan. Cooler condition with high rainfall can be estimated in zone MD2195-1 (42-40.5 ka). Larger area of continental shelf in the ECS and Yellow Sea was exposed to the land during the large drop in the sea level in zones MD2195-2 (40.5 -17 ka) and -3 (17-14 ka). High abundance of nonarboreal pollen in Zones MD2195-2 and -3 is attributed to reduced distance, exposed continental shelf and ocean current system. Rainfall could have been diminished in zone MD2195-2. Climate could begin to warm up in zone MD2195-3. Sharp decrease in abundance of nonarboreal pollen due to rapid transgression characterizes zone MD2195-4 (14-8 ka). Warm temperate-subtropical evergreen broad-leaved pollens developed in zone MD2195-5. The occurrence of Phyllocladus, originating from high land of New Guinea, Indonesia Maritime Continent and Philippines, between upper zone MD2195-2c and zone MD2195-4 suggests that Kuroshio Current flowed through the ECS during the last glacial times.