Pelagic Recards From The Equatorial Ninetyeast Ridge And Significant Environmental Events During Past 3.5 Million Years

Ninetyeast Ridge lies at the NE Indian Ocean.It is 1000m higher thanthe sea floor. when the Bengal deep sea fan hosted most of erosion productsfrom Tibetan Plateau,it is minor reformed by turbidity and bottom currentsactivity, It is mainly documented by pelagic and himipelagicsedimentation. it contains some initial information of the sedimentaryprocess.As such, it can be served as an ideal situation to some long-termresearch on paleoceanography.Here we present the planktic foraminifera faunal ,the stable isotopeand weight content of CaCO3 records of ODP758 from Ninetyeast Ridge tothe rapid uplift of Tibetan Plateau,We discuss the changes of theimportant tectonics and environment events,such as mid-PlestoceneTransition,mid-Brunhes Dissolution Event.Based on the theory analysis and comparison, We indicate that thepaleoclimatic changes maybe correlated with the mid-PlestoceneTransition at 1.4-0.7 Ma by the changes of planktic foraminifera faunal,salinity ,temperature and themoclin from ODP site758. The changes of massaccumulation rate(MAR) of CaCO3 and non- CaCO3 MAR indicate that the loadedterrigenous sediments increased at 1.6 Ma.It is accord with the documentsof rapid uplift of Himalayas.The last two changes coincided with theuplift of Tibetan Plateau,so called "Tibet Movenent"and"Kunlun-Huanghe Movement".The Changes of the CaCO3 content,coarsefraction(>150μm) content and planktonic foraminifera faunal variationsshow that the dissolution of CaCO3 was great during 0.5-0.4 Ma.The eventhas been found in Alantic Ocean,Pacific Ocean,the other sites of IndianOcean and Nansha of South China Sea. This indicates the event widelyoccurred through the whole ocean system.