Spatial-temporal Characteristics of Holocene Paleosols in the Chinese Loess Plateau and Paleoclimatic Significance  

作　　者：GUO Xuelian HE Lusheng ZHAO Guoyong WANG Weibin CAO Huairen WU Hao 

机构地区：[1]Key Laboratory of Western China’s Mineral Resources of Gansu Province,School of Earth Sciences,Lanzhou University,Lanzhou 730000,China [2]College of Urban and Environmental Science,Xinyang Normal University,Xinyang 464000,China

出　　处：《Chinese Geographical Science》2022年第6期1110-1118,共9页中国地理科学（英文版）

基　　金：Under the auspices of the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(No.2019QZKK0704);Natural Science Foundation of China(No.41772168,42103046);Natural Science Foundation of Gansu Province(No.20JR5RA272,20JR5RA226)。

摘　　要：The evolution of Holocene climate was investigated using grain size and magnetic susceptibility of the Holocene paleosols from Baicaoyuan(BCY),Xifeng(XF) and Linyou(LY) sections in the northwest,central and southern Chinese Loess Plateau(CLP).The results show that the Holocene in the B CY,XF and LY paleosol sections could be divided into three phases:during the early Holocene(11.8-10.5 kyr B.P.),increased magnetic susceptibility(χ) and frequency-dependent magnetic susceptibility(χ) and decreased median grain size(Md) indicate that the East Asian Summer Monsoon(EASM) has become more intense and the climate has changed from cold to warm.During the middle Holocene(10.5-5.0 kyr B.P.),the values of χ,χand 2-5 μm grain-size fraction(GT2/5) are higher and Md and 30-63 μm grain-size fraction(GT3 0/6 3) are the lowest,which reflect a warm and humid regional climate.At~8.0 kyr B.P.,there was a transient dry-cold climatic spike corresponding to a Heinrich Event,the cold event was likely due to the collapse of the Laurentide ice sheet.During the late Holocene(5.0-0 kyr B.P.),χ and χvalues are the lowest,while Md and GT30/63 are high,as proxies of a weakened EASM,when the dry-cold climate prevailed in the region.Decreased irradiance since 5.0 kyr B.P.may have caused climatic cooling and drying.Spatially,the increased main peak values and skewness from BCY,XF to LY sections show that the grain size became fine,the East Asian Winter Monsoon(EAWM) reduced,and climate was warmer and wetter from northwest to southeast.In addition,Md can be used as alternative proxy for EAWM,while χis positive with the intensity of EASM under semiarid climate conditions in CLP.

关 键 词：HOLOCENE magnetic susceptibility grain size PALEOCLIMATE Chinese Loess Plateau(CLP) 

分 类 号：P534.632[天文地球—第四纪地质学] P532[天文地球—古生物学与地层学]