论文部分内容阅读
YQ0902孔位于瓯江三角洲南翼的海岸平原上,沉积相与AMS~(14)C测年分析表明,钻孔底部为MIS 3阶段的河湖相沉积,之上为形成于MIS 2的硬粘土层。约在10cal.kaB.P.海侵到达本区,沉积了一套厚约29m的海侵-海退沉积旋回。古气候重建表明,50～35cal.kaB.P.凉爽干燥,35～25cal.kaB.P.温和湿润,25～10cal.kaB.P.寒冷干燥,10～9cal.kaB.P.凉爽偏干,9.0～6.5cal.kaB.P.暖热潮湿,6.5～4.8cal.kaB.P.温凉偏干,4.8～1.8cal.kaB.P.温暖潮湿,1.8cal.kaB.P.之后趋同于现代气候。受中全新世东亚夏季风减弱影响,研究区降雨减弱始于6.5cal.kaB.P.,这与前人研究认为季风区降雨减弱年限随纬度增加有时滞的观点相一致。孢粉记录的两次百年尺度(6.9～7.3cal.kaB.P.和5.0～5.5cal.kaB.P.)降温事件,与全球性强降温事件(7.3cal.kaB.P.和5.5cal.kaB.P.)有较好的对应关系。
The YQ0902 pore is located on the coastal plain in the south wing of the Oujiang delta. Sedimentary facies and AMS ~ (14) C dating analysis indicate that the bottom of the borehole is a lacustrine facies sedimentation at the MIS 3 stage, above which is a hard clay formed on MIS 2 Floor. About 10cal.kaB.P. Transgression reached the area, deposited a set of about 29m thick transgression - regression sedimentary cycle. Paleoclimate reconstruction shows that it is cool and dry at 50 ~ 35cal.kaB.P., 35 ~ 25cal.kaB.P. mild and humid, 25 ~ 10cal.kaB.P. cold and dry, 10 ~ 9cal.kaB.P. cool and dry, 9.0 ~ 6.5cal.kaB.P. Warm and humid, 6.5 ~ 4.8cal.kaB.P. Warm and dry, 4.8 ~ 1.8cal.kaB.P. Warm and humid, 1.8cal.kaB.P. After convergence with the modern climate. Affected by the weakening of the Mid-Holocene East Asian summer monsoon, the rainfall weakened in the study area started at 6.5cal.kaB.P., which is consistent with the previous studies that the monsoon rainfall attenuation period is delayed with latitude. Sporopollen records two cooling events on the centennial scale (6.9-7.3 cal.kaB.P. and 5.0-5.5 cal.kaB.P.), with global cooling events (7.3 cal.kaB.P. and 5.5 cal. kaB.P.) has a good correspondence.