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通过对南海西部越南岸外MD05-2901孔的有孔虫氧同位素测定,建立了450ka以来高分辨率的年代地层.结合沉积物的密度、孔隙率和陆源碎屑含量,计算了陆源碎屑的堆积速率,结果显示在间冰期时堆积速率的平均值为4.9~6.0g/(cm2·ka),高于冰期的1.9~5.0g/(cm2·ka),与发表过的南海南、北部冰期高于间冰期的特点明显不同.对陆源沉积物的粒度分布进行主成分因子分析,获得了两个主控因子F1和F2,它们控制了陆源沉积近80%的粒度变化特征.对F1敏感的1.26~2.66μm%1)和10.8~14.3μm%呈现高频的波动,和北半球低纬夏季太阳辐射量吻合很好,显示23ka的岁差周期和13ka的半岁差周期.对F2敏感的4.24~7.42μm%和30.1~43.7μm%,则显示强烈的100ka的偏心率周期.本区的陆源沉积物来源于南海西南和北部2个地区,在动力上则分别由夏季风和冬季风驱动的不同方向的洋流搬运.研究认为,晚第四纪以来东亚夏季风受控于低纬区的夏季日射量的变化,而冬季风主要受高纬冰盖变化驱动,呈冰期/间冰期旋回尺度的波动,这反映了东亚季风演化的双重驱动机制.
Based on the determination of the foraminiferal oxygen isotope of MD05-2901 hole in the west coast of the South China Sea, a new generation of high-resolution chronostratigraphy has been established. Combining the sediment density, porosity and terrigenous clastic content, The results show that the average accumulation rate during the interglacial period is 4.9-6.0g / (cm2 · ka), which is higher than that of 1.9-5.0g / (cm2 · ka) in ice age, Which is obviously different from the interglacial period.The principal component factors of the grain size distribution of terrestrial sediments were analyzed and two main control factors F1 and F2 were obtained which control the grain size change characteristics of nearly 80% 1.26 ~ 2.66μm% 1) and 10.8 ~ 14.3μm% showed high frequency fluctuations, and the northern hemisphere low latitude summer solar radiation is very good, showing the 23ka precession period and 13ka preremacy cycle. Sensitive to F2 4.24 ~ 7.42 μm, and 30.1 ~ 43.7μm%, the intense period of 100 ka eccentricity is observed.The terrestrial sediments in this area come from two regions of southwest and north of the South China Sea, and they are driven by summer monsoon and winter monsoon respectively in different directions Of the ocean current carrying .Studies believe that since the late Quaternary East Asia summer Low latitude areas controlled by changes in the amount of sunlight summer day, while the winter monsoon is mainly affected by changes in high-latitude ice sheets driven, fluctuating glacial / inter-glacial cycles scale, reflecting the dual drive mechanism of the East Asian monsoon evolution.