长江现代河流沉积物石英ESR信号强度空间分布特征及其物源示踪意义  

SPATIAL DIVERSITY OF QUARTZ ESR SIGNAL INTENSITY OF THE MODERN YANGTZE RIVER FLUVIAL SEDIMENTS AND ITS IMPLICATIONS FOR SEDIMENT PROVENANCE

作　　者：魏传义[1] 尹功明[1] 刘春茹[1] 李亚伟 姬昊 郭汝军 WEI Chuanyi;YIN Gongming;LIU Chunru;LI Yawei;JI Hao;GUO Rujun(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029;College of Tourism and Planning,Pingdingshan University,Pingdingshan 467400,Henan;School of Geography and Information Engineering,China University of Geosciences(Wuhan),Wuhan 430074,Hubei)

机构地区：[1]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 [2]平顶山学院,旅游与规划学院,河南平顶山467400 [3]中国地质大学(武汉)地理与信息工程学院,湖北武汉430074

出　　处：《第四纪研究》2022年第4期1168-1180,共13页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42002203、41772185和42172211);科技部科技基础资源调查专项项目(批准号:2021FY100102)共同资助。

摘　　要：近年来,石英ESR信号强度在风成沉积和河流沉积中都已被证明为一种行之有效的物源示踪指标。文章以长江流域干流不同河段及其主要支流为研究对象,共采集20个现代河流沉积物样品,对其粒度组成特征及其石英自然E′_1心,辐照5000 Gy的Al心、Ti心的ESR信号强度空间分布特征及其物源示踪意义进行了探讨,主要取得了以下初步认识:1)长江流域沉积物从上游地区到中下游地区经历了长时间、长距离的搬运,经过了充分的混合,且呈现“沿程细化”之趋势;本研究的长江流域干流河段及其主要支流(河漫滩及江心洲)的沉积物主要以125~500μm的粒径组分为主,约占全样组分的60%~90%(平均为80%)。2)从上游河段到中下游河段,长江主要支流和干流不同河段沉积物石英自然E′_1心,辐照后的Al心和Ti心ESR信号强度都表现出了较好的空间分异性,即上游河段处于低端元值域而下游河段处于高端元值域。3)长江上游地区以及汉江是长江中下游干流沉积物的主要贡献者,而中下游地区的鄱阳湖水系和洞庭湖水系对长江干流物质的贡献度非常低。The Yangtze River is the longest river derived from the Tibetan Plateau,and the third largest river in the world,which delivers a large volume of sediment into the Asian marginal seas. Recognition of the source to sink proceeding of fluvial sediment can provide an insight into understanding the relationship and interaction between tectonic,geomorphologic and climatic processes. The studied minerals used for sediment provenance tracing of the previous studies were mainly focus on heavy minerals;however,the quartz,one of the most common minerals on the surface of the earth and a primary rock-forming mineral across the rock cycle,is rarely studied.Recently,the quartz electron spin resonance ( ESR) signal intensity of multiple centers has been successfully applied into the provenance tracing of the modern fluvial sediment. Here we present a multiple group dataset of ESR signal intensity on different fractions of detrital quartz extracted from 20 samples collected from the different Yangtze River catchment and major tributaries,to investigate if the ESR signal intensity could be used as an indicator of large river sediment provenance. Moreover,we also analyzed the grain size composition of the modern Yangtze samples in order to better understand the quartz transportation of different fraction. The preliminary results are summarized as follows: ( 1) Grain size analysis results showed that the priority size fraction of the modern Yangtze fluvial sediment was 125 ~ 500 μm,occupied 80% of the bulk samples. Then is the finer fraction ( < 125 μm) and courser fraction(>500 μm) ,which occupied about 20% of the bulk samples. The particles in mainstream show a fining trend of sediment grain size from upper reaches to middle-lower reaches. ( 2) Nature E’center,Al center and Ti center( with5000 Gy gamma ray dose after heating 15 minutes at 300 ℃ ) signal intensity of quartz extracted from mainstream and major tributaries varied significantly among the Yangtze River basin. The nature E’center ( 0. 2 m W) ESR signal intens

关 键 词：长江 现代沉积物 石英 ESR信号 物源示踪 

分 类 号：P512.31[天文地球—地质学] P597.3