关键词: 磁化率, 粒度, 晚冰期, 气候与环境变化, 江淮平原

Abstract:

The Jianghuai Plain, which is located in the margin area of Chinese important climate separatrix—Qinling-Huaihe River, is sensitive to global climate and environment change. It is also located in the monsoon triangle area of China, which is under the influence of the East Asian monsoon. So the area is very important for recording the Paleoclimatic and Paleoenvironmental changes. A sediment core from Jianghuai Plain was chosen for this study. The climate history of the Jianghui Plain during the past 19 230 cal a B.P. was resumed, which based on the analyses of chronology, magnetic susceptibility and Grain Size of YZQ Core Sediments from this area. Since 19 230 cal a B.P., this region climate had a tread of humidity, although the area of Jianghuai Plain had experienced alternatons of relative cold-dry and warm-moisture period. The climate change pattern of the studied area may have global background. On the other hand, it also incarnates evident regional characteristics. During the research period, the paleoclimatic changes history was reconstructed as follows:1) 19 230-14 150 cal a B.P. (633-497 cm): The climate index of grain size and magnetic susceptibility shows the hydrodynamic conditions were too weak to carry materials. The climate environment characteristic was less precipitation in this period. Some short-term climate events occurred under the arid background condition. 2) 14 150-12 950 cal a B.P. (497-455 cm): This period is the interstadial characterized by warm and wet before the end of the Last glacial. Between the warm and wet climate, the cold and arid period must be the Older Drays climate event. 3) 12 950-11 290 cal a B.P. (455-397 cm): The climate was the most obvious dry during our study period. The regional precipitation decreased significantly. And the carrying capacity significantly weakened, resulting in substantial declining hydrodynamic force. 4) 11 290-7 450 cal a B.P. (397-262 cm): The climate index indicates that this period should be hot and humid since the Holocene. There were twice cold and dry fluctuations in 10 300 cal a B.P. and 8 250 cal a B.P. 5) 7 450-4 950 cal a B.P. (262-175 cm): In this stage, the regional precipitation reduced gradually and the climate became warm and dry. 6) 4 950-1 510 cal a B.P. (175-52 cm): This period climate environment was warm and humid. Precipitation was relatively more and hydrodynamic force was strong. During 3 500-2500 cal a B.P., the precipitation and hydrodynamic force had a certain degree of weakening. The climate had a tendency to become cold and dry.

Key words: magnetic susceptibility, grain size, the late glacial period, paleoclimatic and paleoenvironmental evolution, Jianghuai Plain