临汾盆地晚第四纪地层划分与新构造运动分析  

Division of Late Quaternary Strata and Analysis of Neotectonic Movement in Linfen Basin

作　　者：史双双[1,2] 赵强[1,2] 赵晋泉[1,2] 蒋汉朝[3] 李自红[1,2] 

机构地区：[1]山西省地震局,山西太原030021 [2]太原大陆裂谷动力学国家野外科学观测研究站,山西太原030025 [3]中国地震局地质研究所,地震动力学国家重点实验室,北京100029

出　　处：《地震工程学报》2016年第4期624-631,共8页China Earthquake Engineering Journal

基　　金：中国地震局监测、预测、科研三结合课题(160401);山西地震局科研项目(SBK-1633)

摘　　要：为划分临汾盆地第四纪地层,在临汾市东布设1个控制性钻孔,描述其所揭示的地层岩性特征。通过对钻孔剖面中269件孢粉样品的孢粉组合进行分带讨论,结合9个光释光样品和12个电子自旋共振样品的年龄测试结果,认为该控制性钻孔记录了379ka B.P.以来的沉积地层,其中埋深0~0.4m属于全新统,0.4~80.8 m属于上更新统（孢粉记录揭示出相对干燥寒冷的古气候特征,终末期气候转暖,降水增多）,埋深80.8m以下属于中更新统（代表了温暖潮湿的古气候特征）。晚更新世以来平均沉降速率为0.64mm/a,远高于临汾盆地第四纪平均断陷速率,表明晚更新世以来临汾盆地的新构造运动呈现增强趋势。As the Quaternary strata of Linfen Basin have not yet been systematically analyzed,in this study,we performed a controlled borehole in the middle of the Linfen depression to expose the Quaternary strata in Linfen Basin.We employed a controlled borehole in this project to detect active faults and assess seismic risk in Linfen City from 2009 to 2014.The final hole depth was245 mat the coordinates 111°34′56″E,36°3′55″N.Based on the formation of the strata exposed by the borehole,we determined that the strata are divided into 39 composite layers.The sediment in the lower parts of the section is darker and is characterized by a brownish red silty clay layer,which is representative of a strong oxidizing environment.The sediment of the upper part of the section is fine-grained and is dominated by lacustrine deposits.We processed 269 effective pollen samples to analyze the characteristics of the sporo-pollen assemblages in the drilling section.Based on the obvious changes in the pollen content of the spore trees,shrubs,and herbs and from the fern content in the section,we divided the sporo-pollen assemblages into six categories as follows：Ⅰ（245~152m）,Ⅱ（152~84m）,Ⅲ（84~51.5m）,Ⅳ（51.5~25.5 m）,Ⅴ（25.5~12.5m）,andⅥ（12.5~0.5m）.We collected nine core samples in the upper part of the section to analyze the absolute age of the sediment by optically stimulated luminescence dating.We also collected twelve core samples in the lower part of the section to analyze the absolute age of the sediment by electron spin resonance.Dating results show that the control borehole records the sedimentary formation from approximately 379 ka B.P.Sediments at a borehole buried depth of 0~0.4mbelong to the Holocene strata.Sediments at the borehole buried depth of 0.4~80.8mbelong to the upper Pleistocene.Based on the pollen records,we characterized the paleoclimate as being dry and cold during this period,which then warmed and had increased precipitation near the end-stage of this period.Borehole sediments bu

关 键 词：孢粉组合 晚第四纪 古环境 新构造 临汾盆地 

分 类 号：P542[天文地球—构造地质学]