河流过程对小型集水区沉积物地球化学与重矿物组成的影响——以巴兰河为例  

Effects of Fluvial Processes on Sediment Geochemistry and Heavy Mineral Composition in a Small Catchment:A case study of the Balan River

作　　者：赵慧莹 谢远云[1,2] 迟云平[1,2] 康春国[3] 吴鹏 孙磊 魏振宇 ZHAO HuiYing;XIE YuanYun;CHI YunPing;KANG ChunGuo;WU Peng;SUN Lei;WEI ZhenYu(College of Geographic Science,Harbin Normal University,Harbin 150025,China;Heilongjiang Province Key Laboratory of Geographical Environment Monitoring and Spatial Information Service in Cold Regions,Harbin Normal University,Harbin 150025,China;Geography Department,Harbin University,Harbin 150086,China)

机构地区：[1]哈尔滨师范大学地理科学学院,哈尔滨150025 [2]哈尔滨师范大学寒区地理环境监测与空间信息服务黑龙江省重点实验室,哈尔滨150025 [3]哈尔滨学院地理系,哈尔滨150086

出　　处：《沉积学报》2025年第1期63-75,共13页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42171006,41871013)。

摘　　要：【目的】河流沉积物记录了丰富的源区信息,对于探究流域源区风化、搬运—沉积循环及母岩成分具有重要意义。与整合了不同风化机制并包含复杂岩石类型的大型流域不同,小型河流具有相似的气候和岩性背景,对研究沉积物物质组成有重要研究价值。【方法】为了探究河流过程对沉积物物质组成的影响,将从巴兰河上游到下游的边滩上获取的8个样品进行分粒级处理(<63μm、63~125μm、125~250μm),将小于63μm的样品进行地球化学测试(常量、微量、稀土和Sr-Nd同位素),63~125μm和125~250μm的样品进行重矿物测试。【结果】巴兰河沉积物经历了较低的化学风化作用、成熟度较低,处于初次循环沉积,物源主要来源于长英质母岩。物源指标(La/Sc、Co/Th、Cr/Th、Th/Sc)和Sr-Nd同位素组成总体变化较小,能够代表巴兰河总体流域特征。【结论】巴兰河样品呈现出一致的化学风化程度、成熟度、再循环特征、母岩特征,这说明河流过程并没有对巴兰河沉积物的地球化学组成造成明显影响。重矿物经过河流的搬运后稀释混合,不同河段及不同粒级组分的重矿物明显呈现不同的含量组成,表明短距离的搬运很难使重矿物均匀分配到不同粒级组分。因此,在进行河流源—汇系统研究时,少数的样品很难代表整个流域的重矿物组成,即便是在小型河流中。另外,强调了Sr-Nd同位素与不活动元素比值结合可以有效进行河流物源示踪。[Objective]River sediments record abundant information about their source,which is significant for ex-ploring weathering,the transport-sedimentation cycle and parent rock composition in the source region of the basin.Unlike large watersheds that may integrate a range of weathering mechanisms and contain complex rock types,small rivers have similar climatic and lithological backgrounds,which provides valuable information when studying sedi-ment composition.[Methods]In order to explore the influence of fluvial processes on sediment composition,eight samples were obtained from the upper and lower of the Balan River for granular processing(<63μm,63-125μm,125-250μm).The<63μm samples were subjected to geochemical testing(major,trace,rare earth and Sr-Nd isotopes).The 63-125μm and 125-250μm samples were tested for heavy minerals.[Results]It was found that the sediments in the Balan River have undergone low chemical weathering,are of low maturity,and are in the primary cycle of deposition.The provenance is mainly from felsic parent rock.The provenance indices(La/Sc,Co/Th,Cr/Th,Th/Sc)and Sr-Nd isotopic compositions showed little change overall,which represents the overall characteristics of the Balan River basin.[Conclusions]The Balan River samples showed consistent chemical weathering,maturity lev-els,recycling characteristics and host rock properties,indicating that the fluvial process had not significantly affect-ed their geochemical composition.The heavy minerals were diluted and mixed after river transport;those from differ-ent river reaches and with different grain size fractions showed obviously different compositional content.This indi-cates that short-distance transport is unlikely to evenly distribute heavy minerals within different grain size fractions.Therefore,when studying river source-sink systems,a small number of samples does not necessarily represent the heavy mineral composition of the entire basin,even in small rivers.This study also emphasizes that the combination of Sr-Nd isotope and inactive e

关 键 词：巴兰河 河流过程 地球化学组成 重矿物 SR-ND同位素 

分 类 号：P595[天文地球—地球化学]