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

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 mu m) 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 mu m) 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 mu m) 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.