【摘要】 为了探索和揭示2.5MaBP前后东亚季风演变历史及植被演替对气候演化的响应,对南海南部大洋钻探ODP1143站(9°22′N、113°17′E)深海柱状样的上部135~95m(3.0~2.0MaBP)共146个孢粉样品进行了分析研究,时间分辨率为7ka/样,孢粉谱显示沉积率变化显著,以2.6MaBP为界可明显分为两个阶段,与前一阶段3.0~2.6MaBP相比,2.6~2.0MaBP时段各类型花粉及孢子沉积率均有显著提高。该结果表明2.6MaBP南海海平面有显著下降,可与北半球冰盖形成、东亚季风增强相对应。2.6MaBP以后,各类型孢粉沉积率高低变化揭示南海海平面有多次上升和下降,代表了多次冰期—间冰期旋回。该结果与深海氧同位素分期相对应。频谱分析表明3.0~2.0MaBP存在0.1Ma(偏心率)和46.9ka(斜率)的周期。更多还原

【Abstract】 Totally 146 pollen samples, with an average time resolution of 7 000 ka at the depth of 135～95 m in deep-sea records from ODP Site 1143 (9°22′N,113°17′E)in the southern South China Sea, were analyzed to study the history of East Asian paleo-monsoon evolution and the response of vegetational evolution in the SCS ambient areas to climatic variations around 2.5 MaBP. The average time resolution is 7 000 years. The results showed that the pollen influx had a distinct change. The average value of pollen influx during 2.6～2.0 MaBP is different from that of 3.0～2.6 MaBP and increased notably. The fact shows that the sea level of the SCS fell distinctly at 2.6 MaBP, which is in correspondence with the formation of the Northern Hemisphere glaciation and the enhancement of the East Asian Monsoon. The correspondence of pollen influx changes with oxygen isotope stages represents many cycles of glaciation-interglaciation, indicating the corresponding rises and falls of the sea level of the South China Sea occurred after (2.6 MaBP.) Results of spectrum analysis showed that 0.1 Ma(eccentricity) and 46.9 ka(obliquity) cycles existed during 3.0～2.0 MaBP.更多还原