山西长治盆地中更新世气候转型期环境变化特征  

Characteristics of environmental changes during the Mid-Pleistocene transition period in the Changzhi basin,Shanxi Province

作　　者：李金秋[1,2] 李向全 范保硕[3,4] 王振兴 李月丛 刘林敬[1,2] 侯新伟 张春潮[1,2] LI Jinqiu;LI Xiangquan;FAN Baoshuo;WANG Zhenxing;LI Yuecong;LIU Linjing;HOU Xinwei;ZHANG Chunchao(Institute of Hydrogeology and Environmental Geology,China Academy of Geological Sc iences,Shijiazhuang,Hebei 050061,China;Key Laboratory of Quaternary Chronology and Hydro Environmental Evolution,China Geological Survey,Shijiazhuang,Hebei 050061,China;College of Resource and Environmental Sciences,Hebei Normal University,Shijia xhuang,Hebei 050024,China;Key Laboratory of Environmental Change and Ecological Deuelopment of Hebei Prorince,Shijiazhuang,Hebei 050024,China)

机构地区：[1]中国地质科学院水文地质环境地质研究所,河北石家庄050061 [2]中国地质调查局第四纪年代学与水环境演变重点实验室,河北石家庄050061 [3]河北师范大学资源与环境科学学院,河北石家庄050024 [4]河北省环境演变与生态建设重点实验室,河北石家庄050024

出　　处：《地质学报》2021年第11期3532-3543,共12页Acta Geologica Sinica

基　　金：中国地质调查局项目(编号121201106000161309);中国地质科学院基本科研业务费项目(编号JYYWF20180401);河北省应用基础研究计划重点基础研究项目(编号18963301D)联合资助的成果。

摘　　要：中更新世气候转型(MPT)是第四纪环境变化的一个重要时期,该时期气候模式、气候周期等均发生了明显变化,然而不同区域对中更新世气候转型的响应特征存在明显差异。本研究选取了长治盆地XZK4钻孔中更新世转型前后(1.8~0.1 Ma)共207个样品,通过古地磁定年,运用粒度端元分析和孢粉分析,阐述了长治盆地中更新世转型期的环境变化与湖泊演化特征。结果显示,1.8 Ma以来,孢粉组合中乔木花粉含量多高于60%,但个别时段草本植物花粉占优,显示区域植被多数阶段为森林,但存在明显冷期,并且1.1 Ma和0.55 Ma是研究区环境转变的重要转折点。中更新世转型期前(~1.1 Ma):沉积物粒度总体较细,黏土含量多高于25%,EM1组分(湖相沉积)多高于60%,EM3(河流相组分)在个别时段出现,总体显示该阶段沉积物组成以湖相沉积为主,个别阶段受到河流影响大;中更新世转型时期(1.1~0.55 Ma):沉积物粒度较上一阶段更细,黏土含量(平均为30%)、EM1占比和孢粉浓度均达到研究段最高,沉积物颜色以棕灰色为主,EM3组分占比降至最低,其中1.1~0.95 Ma喜冷的云杉属花粉出现,显示该时期研究区气候总体偏冷湿,湖泊面积较1.1 Ma之前扩大;中更新世转型后(~0.55 Ma):沉积物粒度明显变粗,达到钻孔最高值,沉积物颜色变黄,EM2(风成组分)和EM3占主导,草本植物含量增加,尤其是喜干的蒿属花粉增加明显,表明气候较之前变干,沉积物类型以风力沉积为主,湖泊消亡。综合对比显示,构造运动是影响长治古湖消长的主要驱动力,气候变干加剧了湖泊消亡。The Mid-Pleistocene transition(MPT)is an important period of Quaternary environmental change,during which climatic patterns and cycles changed significantly.However,the response characteristics of different regions to the Mid-Pleistocene transition were significantly different.In this study,207 samples were selected from the XZK4 core in the Changzhi basin before and after the Mid-Pleistocene transition.By means of paleomagnetic dating,grain-size,End-Member and pollen analysis,the characteristics of environmental changes and lake evolution during the Mid-Pleistocene transition period in the Changzhi basin were reconstructed.The results showed that since 1.8 Ma(i)the content of tree pollen in the pollen assemblage was more than 60%;(ii)some periods were dominated by herbs pollen indicating that most stages of regional vegetation were forests,but there were obvious cold periods;and(iii)the interval 1.1 Ma and 0.55 Ma was an important turning point of environmental transformation in the study area.Before the Mid-Pleistocene transition(~1.1 Ma),the overall grain-size of the sediments was relatively fine,the clay content was more than 25%,the EM1 component(representing lacustrine components)was more than 60%,and the EM3 component(representing fluvial facies component)appeared in some periods.The overall results showed that the sediments in this stage were mainly lacustrine components,and some stages were greatly affected by rivers.However,during the Mid-Pleistocene transition(1.1~0.55 Ma),sediment grain-size were finer with average 30%clay content,sediment color was predominantly gray-brown,and pollen concentrations and EM1 component achieved the highest values,while EM3 component was at its lowest,during 1.1~0.95 Ma,Picea pollen shows that the study area was generally cold and wet,and the lake area expanded.After the Mid-Pleistocene transition(~0.55 Ma),sediment grain-size was significantly coarser,sediment color was predominantly yellow,EM2(indicating eolian component)and EM3 are dominant,herbs content increased,esp

关 键 词：中更新世气候转型 粒度分析 环境变化 长治盆地 

分 类 号：P534.631[天文地球—第四纪地质学] P532[天文地球—古生物学与地层学]