Magnetic characterization and paleoclimatic significances of late Pliocene-early Pleistocene sediments at site 882A,northwestern Pacific Ocean  

作　　者：JIANG ZhaoXia LIU QingSong 

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing100029,China [2]Graduate University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science China Earth Sciences》2012年第2期323-331,共9页中国科学（地球科学英文版）

基　　金：supported by National Natural Science Foundation of China (Grants Nos. 40974036, 41025013 and 40821091);the CAS/SAFEA International Partnership Program for Creative Research Teams

摘　　要：Aeolian dust, a primary terrigenous component of ocean sediments, has been widely used to reconstruct the paleoclimatic evolution because its transported distance, grain size and concentration are sensitive to climate changes. To further characterize the aeolian dust, the deposits at site Ocean Drilling Program (ODP) 882A in northwestern Pacific Ocean are divided into four grain-size fractions (<8, 8-16, 16-64, >64 μm) using the gravitative differentiation method. Detailed rock magnetism results show that magnetite and hematite are dominant magnetic minerals for the dust components. In addition, the aeolian dust (<8 μm) represented by the concentration of magnetic minerals increases sharply at 2.73 Ma, which corresponds to the onset of major glaciation in the Northern Hemisphere. In contrast, the ice-rafted detritus (IRD) (>64 μm) contributes little to the magnetic enhancement of the sediments at 2.73 Ma. These new results greatly improve our understanding of paleoenvironmental evolution during late Pliocene-early Pleistocene in this area.Aeolian dust, a primary terrigenous component of ocean sediments, has been widely used to reconstruct the paleoclimatic evolution because its transported distance, grain size and concentration are sensitive to climate changes. To further characterize the aeolian dust, the deposits at site Ocean Drilling Program （ODP） 882A in northwestern Pacific Ocean are divided into four grain-size fractions （8, 8-16, 16-64, 64 μm） using the gravitative differentiation method. Detailed rock magnetism results show that magnetite and hematite are dominant magnetic minerals for the dust components. In addition, the aeolian dust （8 μm） represented by the concentration of magnetic minerals increases sharply at 2.73 Ma, which corresponds to the onset of major glaciation in the Northern Hemisphere. In contrast, the ice-rafted detritus （IRD） （64 μm） contributes little to the magnetic enhancement of the sediments at 2.73 Ma. These new results greatly improve our understanding of paleoenvironmental evolution during late Pliocene-early Pleistocene in this area.

关 键 词：eolian dust sediment rock magnetism MAGNETITE HEMATITE ODP site 882A the major glaciation in the Northern Hemisphere 

分 类 号：P736.21[天文地球—海洋地质] X144[天文地球—海洋科学]