QUATERNARY PALYNOLOGICAL STRATA IN OFFSHORE AREA OF THE MIDDLE YELLOW SEA AND THEIR SIGNIFICANCE IN VEGETATION AND CLIMATE STUDY
Li Xu Heng Ping (Institute of Marine Geology, Ministry of Geology & Mineral Resources, Qingdao,China,266071)
By analyzing Hole QC2, with hole depth of 108.8m and water depth of 49m, at 122°16'E, 34°18'N, and located in the offshore area of the middle Yellow Sea, the authors of this paper concluded that Quaternary palynological strata and vegetational and climatic changes in this region can be divided into 7 stages since last 180Ma. There were only a small number of pollen grains in early early Pleistocene, represented by sediment between the hole depth of 108.8 to 101.0m, indicating a cold climate at that time. Pollen assemblage of late early Pleistocene, 101.0 to 80.0m deep, was dominated by tree pollen, mostly of Quercus, Pinus, Castanopsis/Castanea and Fagus, illustrating a type of broadleaved forest in subtropic climate with a temperature about 2.3°C higher than present. Climate during early middle Pleistocene, 80.0 to 61.0m deep, was quite unstable, consisting of four minor fluctuations. In late middle Pleistocene (61.0 to 54.3m), climate became arid-cold with herbs like Artemisia and Chenopodiaceae prevailing in a temperature about 10° to 15°C lower than today. In early late Pleistocene(54.3 to 36.0m), trees of Finns, Quercus, Castanopsis/Castanea and herbs of Artemisia were growing as mixed vegetation,much like the situation of Holocene. Pollen assemblage in late late Pleistocene(36.0 to 17.0m), comprised herb pollen during the last glaciation, indicating a severe unfavourable environment, although there was a temperate phase intercalated. In Holocene, 17.0 to 0.0m, Quercus forest flourished in the warm-humid climate, but in early Holocene the environment was not stable and in late Holocene the vegetation was considerably disturbed by human activity.