摘要
晚新生代黄土高原红粘土的粒度分布具有明显的三峰分布 ,分别在 2～ 2 0、2 0～ 10 0和 0 .0 4～ 1μm出现峰值 ,每个峰值对应于不同的形成过程 ,与晚第四纪黄土一致。方式 C粒子 (0 .0 4～ 1μm)可能代表本底气溶胶粒子的沉积物 ,方式 A粒子 (2 0～ 10 0μm)代表冬季风尘暴搬运的大气粉尘 ,方式 B粒子 (2～ 2 0μm)代表冬季风正常搬运的大气粉尘。红粘土的粒度分布表明 ,东亚冬季风环流而非北半球西风环流控制着红粘土物质的堆积过程。红粘土中 >19μm的粗粒子组分指示了东亚冬季风演化历史 :6 .5 Ma BP冬季风开始发育 ,5 .2～ 4.5 Ma BP冬季风减弱并达到最低值 ,4.5～ 3.6 Ma BP冬季风由弱变强 ,3.6～ 2 .6 Ma BP冬季风快速增强并达到最大值。
Three particle size modes existed in the red clay, each characterized by a log normal distribution, with size ranging from 20 to 100, 2 to 20, and 0 04 to 1 μm in diameter. Like loess sediments, Mode A particles, between 20 and 100 μm in diameter, is considered to be mainly associated with heavy dust transport events. Mode B, between 2 and 20 μm, may represent the ubiquitous dust deposited under all conditions. Mode C, i.e. <1 μm particles, may reflect the deposition of background dust. The size distribution of red clay showed that the accumulation of red clay was controlled by East Asian monsoon circulation rather than westerly circulation. The size (>19 μm fraction) of red clay has indicated that the winter monsoon circulation was established around 6 5 MaBP, but it became weak during 5 2～4 5 MaBP, then strengthened during 4 5～3 6 MaBP. During 3 6～2 6 MaBP, it strengthened quickly and reached its maximum.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2001年第3期99-106,共8页
Marine Geology & Quaternary Geology
基金
国家杰出青年科学基金项目 (4982 5 10 5 )
中国科学院创新重大资助项目 (KZCX2 -3 0 5 )
