孟加拉湾东经90°海岭中上新世以来沉积记录及亚洲季风

Sedimentary Records and Asian Monsoon in Ninetyeast Ridge of Bay of Bengal since Pliocene Time

利用古生物地层学、碳酸盐地层学、X射线粉晶衍射和粒度分析等方法对东北印度洋孟加拉湾东经 90°海岭上的远洋沉积物进行了综合研究 .在此基础上 ,以陆源物质的粒度为切入点对该区的沉积作用、沉积物来源及其可能的搬运机制进行了探讨 ,对过去有关研究区陆源物质的源区和搬运方式作了补充 .陆源物质的粒度可作为东南季风或赤道东风的替代性指标 ,其变化不仅反映源区的火山活动情况 ,而且指示了风力的强弱 .陆源物质的多少则主要取决于青藏高原和印度次大陆的剥蚀情况和地表径流的强弱 .二者之间通过高原隆升及其引发的环境效应联系起来 .

The pelagic sediments of Ninetyeast ridge have been synthetically analyzed through paleobiostratigraphy, carbonate stratigraphy, X-ray crystal powder diffraction and grain size analysis. The grain size of terrigenous sediments has been regarded as a cut-in in the discussion of sedimentation, sources and possible carrying mechanisms of the sediments. The source and carrying pattern of the terrigenous sediments have been supplemented further. The grain size of the terrigenous sediments can serve as an indicator of southeast monsoon or equatorial east wind. Its change not only reflects the volcanic activity of the source region of the terrigenous sediments but also indicates the wind strength. However, the quantity of the terrigenous sediments mainly depends on the erosion of the Tibetan plateau and Indian subcontinent and the runoff. The two aspects have been associated by the uplift of the plateau and its environmental effects.