A rock magnetic record of Asian cooling and aridification processes during 1.95–0.40 Ma in the southeastern Chinese Loess Plateau  

作　　者：WU Yi ZHU ZhaoYu QIU ShiFan RAO ZhiGuo 

机构地区：[1]Key Laboratory of Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences [2]Key Laboratory of Marginal Sea Geology,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences [3]Key Laboratory of Western China's Environment Systems (Ministry of Education),Lanzhou University

出　　处：《Chinese Science Bulletin》2013年第30期3636-3644,共9页

基　　金：supported by the National Basic Research Program of China(2010CB833405);the National Natural Science Foundation of China(41102115 and 40930106)

摘　　要：The southeastern Chinese Loess Plateau is the terminal deposition area of dusts transported by the East Asian winter monsoon and the frontal area penetrated by the East Asian summer monsoon,and thus a climate sensitive region.This paper reports a rock magnetic study of a Quaternary loess-paleosol section in such a region.We tried to reconstruct the paleoclimate evolution history in the region during 1.95–0.40 Ma with magnetic parameters.The results show a general up-section decreasing trend of the ratio of HIRM/(SIRM–IRM100 mT),indicating a long-term decreasing trend of hematite coercivities in the deposits,which can be mainly related to the cooling and aridification trend of the environment in interglacial depositional area and glacial dust source region.The ratio,lf/ARM,widely used to reflect the variations of magnetic mineral grain size,manifests a long-term increasing trend of the magnetic mineral grain size and tends to indicate an overall weakening trend of the East Asian summer monsoon that controlled the pedogenic intensity.Although the regional multi-segmented paleoclimatic records revealed by several magnetic parameters in our study,the long-term Asian cooling and aridification trend inferred here is of global correlation significance.The southeastern Chinese Loess Plateau is the terminal deposition area of dusts transported by the East Asian winter monsoon and the frontal area penetrated by the East Asian summer monsoon, and thus a climate sensitive region. This paper reports a rock magnetic study of a Quaternary loess-paleosol section in such a region. We tried to reconstruct the paleoclimate evolution history in the region during 1.95-0.40 Ma with magnetic parameters. The results show a general up-section decreasing trend of the ratio of HIRM/（SIRM-IRM100 mT）, indicating a long-term decreasing trend of hematite coercivities in the deposits, which can be mainly related to the cooling and aridification trend of the environment in interglacial depositional area and glacial dust source region. The ratio, ХIf/ХARM, widely used to reflect the variations of magnetic mineral grain size, manifests a long-term increasing trend of the magnetic mineral grain size and tends to indicate an overall weakening trend of the East Asian summer monsoon that controlled the pedogenic intensity. Although the regional multi-segmented paleoclimatic records revealed by several magnetic parameters in our study, the long-term Asian cooling and aridification trend inferred here is of global correlation significance.

关 键 词：中国黄土高原 干旱化趋势 中国东南部 岩石磁学 长期冷却 磁性记录 亚洲 古气候演变 

分 类 号：P532[天文地球—古生物学与地层学]