HR: 0830h
AN: GP41B-0046    [PDF]
TI: Quaternary Mineral Magnetic and Free Iron Records of Climatic Change from Chinese Loess/Paleosol Sequence
AU: * Deng, C
EM: cldeng@mail.igcas.ac.cn
AF: Paleomagnetism Laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China
AU: Verosub, K L
EM: verosub@geology.ucdavis.edu
AF: Department of Geology, University of California, Davis, 95616 United States
AU: Singer, M J
EM: mjsinger@ucdavis.edu
AF: Department of Land, Air and Water Resources, University of California, Davis, 95616 United States
AU: Vidic, N J
EM: njvidic@ucdavis.edu
AF: Department of Geology, University of California, Davis, 95616 United States
AU: Vidic, N J
EM: njvidic@ucdavis.edu
AF: Department of Land, Air and Water Resources, University of California, Davis, 95616 United States
AU: Vidic, N J
EM: njvidic@ucdavis.edu
AF: Agronomy Department, University of Ljubljana, Ljubljana, 1111 Slovenia
AU: Zhu, R
EM: rxzhu@mail.igcas.ac.cn
AF: Paleomagnetism Laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China
AB: A high-resolution investigation of mineral magnetism, iron geochemistry and soil physics was carried out on a loess/paleosol sequence from Jiaodao, the central Loess Plateau of China. Our multi-parameter records reveal a gradual decrease in paleo-weathering intensity, and hence a gradual aridification of the Asian continental interior over the past 2.6 Ma, with some fluctuations. The mineral magnetic variations of the lithogenic components could be used to find the links among uplift of the Tibetan Plateau and its adjacent regions, weathering processes in source region, and dust deposition in the Loess Plateau. The changes in free iron (FeD) content and rubification were closely related to long-term paleo-weathering intensity variations in the Jiaodao loess/paleosol sequence during the entire Quaternary, thus attesting to the fact that they are good proxies of summer monsoon evolution. The gradual decrease of FeD content and rubification from the upper part of the Tertiary red clay to the last glacial loess apparently reflects a trend toward greater aridity of the climate system in eastern Asia during the Pleistocene. In addition, the FeD and rubification variations can be described as an asymmetrical saw-tooth pattern. From the upper part of the red clay to the upper sandy loess layer L9, this saw-toothed pattern is consistent with the Earth­_s eccentricity record of the 400-ka period. The features may suggest that the climate system in the Asian continental interior, especially the regional climate controlling atmospheric dust deposition in the Chinese Loess Plateau, is very sensitive to the direct forcing of the 400-ka Earth­_s eccentricity period.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1512 Environmental magnetism
DE: 1519 Magnetic mineralogy and petrology
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting