最近880ka以来黄土-古土壤序列粘土矿物和粘粒地球化学特征及东亚夏季风演化  

CLAY MINERALOGICAL AND GEOCHEMICAL RECORD FROM A LOESSPALEOSOL SEQUENCE IN CHINESE LOESS-PLATEAU DURING THE PAST880 KA AND THE IMPLICATION ON THE EAST ASIAN SUMMER MONSOON

作　　者：吕一凡 张春霞 付扬[2,4] 吴海斌 郝青振[2,3,4] 乔彦松 郭正堂[2,3] LÜYifan;ZHANG Chunxia;FU Yang;WU Haibin;HAO Qingzhen;QIAO Yansong;GUO Zhengtang(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,Shandong;Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;Innovation Academy for Earth Science,CAS,Beijing 100029;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049;Institute of Geomechanics,Chinese Academy of Geological Science,Beijing 100081;Key Laboratory of Neotectonic Movement and Geohazard,Ministry of Land and Resources,Beijing 100081)

机构地区：[1]山东科技大学地球科学与工程学院,山东青岛266590 [2]中国科学院地质与地球物理研究所,中国科学院新生代地质与环境重点实验室,北京100029 [3]中国科学院地球科学研究院,北京100029 [4]中国科学院大学地球与行星科学学院,北京100049 [5]中国地质科学院地质力学研究所,北京100081 [6]国土资源部新构造运动与地质灾害重点实验室,北京100081

出　　处：《第四纪研究》2022年第4期921-938,共18页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42072209和41888101);中国科学院(B类)战略性先导科技专项项目(批准号:XDB26000000)共同资助。

摘　　要：中国黄土-古土壤序列记录了东亚古气候的演化历史。为获取黄土高原南部地区夏季风强度演化特征,以甘肃灵台邵寨L_9以来的黄土-古土壤序列为研究对象,通过X射线衍射(XRD)和X荧光光谱(XRF)方法分别对880 ka以来黄土-古土壤序列粘粒组分的粘土矿物和元素地球化学特征进行了系统分析。研究表明,黄土高原南部地区880 ka以来风尘堆积序列以伊利石为主,其次为蛭石,含少量的1.42 nm混层矿物(HIM)、高岭石和蒙脱石(含I/S),不含绿泥石;粘粒组分中常量元素含量从高至低排列如下:SiO_(2)>Al_(2)O_(3)>TFe_(2)O_(3)>K_(2)O>MgO>CaO>Na^(2)O>TiO_(2)>P_(2)O_(5)>MnO。将粘土矿物组合、粘土颗粒显微结构与粘粒组分元素地球化学特征相结合,系统揭示出邵寨剖面中,蒙脱石(含I/S)和高岭石主要来源于原始风尘碎屑,伊利石包括原始风尘碎屑和后期风化成壤两种来源,蛭石和HIM为成壤风化产物。由于含Na、Fe、Mg元素的蛭石、HIM和蒙脱石(含I/S)含量的变化主要受控于成壤作用的强弱,因此基于上述元素获取的粘粒组分的CIW'(CIW'=100×Al_(2)O_(3)/(Al_(2)O_(3)+Na_(2)O))和TFe_(2)O_(3)/MgO指标很好地记录了古东亚夏季风环流强度的变化历史。研究发现,880 ka以来东亚夏季风环流强度呈间冰期/冰期的强/弱变化特征,在约850 ka、约620 ka、约550 ka、约420 ka和约127 ka等几个间冰期显著增强。The loess-paleosol sequences in Northern China provide an ideal near continuous record of Quaternary paleoclimate in East Asia.There is an almost continuous Quaternary loess-paleosol and red clay sequence in the Shaozhai section(SZ:34°59'17.5″N,107°46'26.5″E),which located in the southeast of the Lingtai District,Pingliang City,Gansu Province.The upper 60 m of the loess-paleosol sequence in the Shaozhai section consists all layers from L_(9) to S_(1).To reveal the evolution history of the East Asian Summer Monsoon(EASM)during the past 880 ka in the southern Chinese Loess Plateau,84 samples are selected from L_(9) to S_(1) loess-paleosol sequence in the Shaozhai section.In this paper,the clay mineral assemblages,and geochemical elements of clay-fractions and microcharacters of clay minerals were analyzed by using X-ray diffraction(XRD),and X-ray fluorescence spectroscopy(XRF)and Scanning Electron Microscope(SEM)methods,respectively.Our results show that clay-fraction minerals are mainly composed of illite(mean:59.9%in loess and 71.9%in paleosol),vermiculite(mean:24.7%in loess and 17.9%in paleosol)and a small amount of HIM(1.42 nm mixed-layer minerals)(mean:5.7%in loess and 5.0%in paleosol),smectite(including of I/S)(mean:5.1%in loess and 0.6%in paleosol)and kaolinite(mean:4.6%in loess and paleosol)in the loess-paleosol sequence.The chlorite is absent in all samples of L_(9)-S_(1) in the Shaozhai section,which is different to the clay mineral assemblages of other areas in the Chinese Loess Plateau.More illite is present in paleosol layers than those loess layers,and smectite(I/S)is absent in all paleosol layers above S_(5).The average content of major elements in clay-fraction of loess-paleosol sequence SiO_(2)(48.87 wt%),Al_(2)O_(3)(22.37 wt%),TFe_(2)O_(3)(10.81 wt%)is higher,followed by K_(2)O(4.02 wt%)and MgO(2.31 wt%),and the average content of CaO(0.68 wt%),Na_(2)O(0.32 wt%),Ti O_(2)(0.77 wt%),P_(2)O_(5)(0.18 wt%),Mn O(0.16 wt%)is very low.The chemical weathering indexes of clay-fraction in paleosol laye

关 键 词：黄土高原 粘土矿物 粘粒组分化学指标 古风化强度 东亚夏季风 

分 类 号：P534.63[天文地球—第四纪地质学] P595[天文地球—古生物学与地层学]