库姆塔格沙漠岩屑的岩石学分析及其物源指示  

Petrological analysis of the lithic fragment in the Kumtagh Desert and its provenance indication significance

作　　者：金秉福 吴波[2,3] 张云吉 于健 韩旭娇 哈斯额尔敦 苏志珠 孔德庸[6] 李秀彬 JIN Bingfu;WU Bo;ZHANG Yunji;YU Jian;HAN Xujiao;HASI Eerdun;SU Zhizhu;KONG Deyong;LI Xiubin(School of Resources and Environmental Engineering,Ludong University,Yantai,Shandong,264025;Institute of Ecological Conservation and Restoration,Chinese Academy of Forestry,Beijing,100091;Key Laboratory of Desert Ecosystem and Global Change,National Forestry and Grassland Administration,Beijing,100091;School of Natural Resources Faculty of Geographical Science,Beijing Normal University,Beijing,100875;Historical Cultre Schuool,Shanxi University,Taiyuan,030006;Shaoguan University,Shaoguan,Guangdong,512005;Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing,100101)

机构地区：[1]鲁东大学资源与环境工程学院,山东烟台264025 [2]中国林业科学研究院生态保护与修复研究所,北京100091 [3]荒漠生态系统与全球变化国家林业和草原局重点实验室,北京100091 [4]北京师范大学地理科学学部自然资源学院,北京100875 [5]山西大学历史文化学院,太原030006 [6]韶关学院,广东韶关512005 [7]中国科学院地理科学与资源研究所,北京100101

出　　处：《地质论评》2024年第5期1998-2014,共17页Geological Review

基　　金：国家自然科学基金资助项目(编号:41471151);国家科技基础性工作专项项目(编号:2012FY111700)的成果。

摘　　要：沙漠中的岩屑是沙源母岩风化的暂时性中间产物,是判别母岩性质和来源的最可靠最直接的标志。采用沙薄片岩性显微鉴定,对库姆塔格沙漠北部的堑谷阶地、边缘台地、羽毛状沙丘以及沙漠南部洪积台地、干河床、边缘沙丘和丘间地等地貌单元的岩块和粗碎屑进行了多样品系统性岩石学分析。结果表明:库姆塔格沙漠岩屑岩石类型复杂,涵盖3大岩类、14种3级岩类、121种5级岩类,以中酸性喷出岩类和区域变质岩类为主,常见的岩石为流纹岩、霏细岩、安山岩、粗面岩、石英岩和石英化岩。碎屑岩矿组成与粒度关系密切,砾石>90%、粗砂50%~90%是岩屑,粒度1.0 mm左右的沙粒岩石类型最多,沙粒细则碎屑单矿物含量高,这种状况使得沙漠不同区域、不同地貌部位沙粒岩性分布存在差异。岩屑具有不同的颜色,暗色颗粒主要由中酸性喷出岩组成,而浅色颗粒主要由石英质岩类和长英质矿物组成,其中部分同类岩屑既有暗色也有浅色。沙漠中岩屑的岩石特征与阿尔金山山区出露的岩性基本一致,沙漠中不仅含有阿尔金山十分发育的动力变质岩类,而且还含有红柳沟—拉配泉段特有的蛇绿岩套混杂岩系的各种岩类,显示出库姆塔格沙漠的碎屑与阿尔金山母岩的渊源关系,但母岩风化的差异性以及山脉隆起不同历史阶段碎屑物输出的差异,使得岩屑中各类岩石的含量与山区母岩含量不尽相同,细晶质及隐晶质且抗风化的岩石成为沙漠岩屑的主要组分。库姆塔格沙漠中粗晶质岩类和碎屑单矿物南多北少与抗风化岩屑北多南少的分布格局是冲洪积物由南向北运移的结果,显示了沙漠沙与冲洪积物岩屑特征的相近性和继承性,揭示了库姆塔格沙漠具有近源就地起沙的物源属性。Objectives:A significant quantity of lithic fragments is observed in the sediment of the Kumtagh Desert,which predominantly comprising coarse-grained materials such as gravel and coarse sand,as a temporary intermediate product of weathering in sedimentary parent rock,the lithic fragments,serve as the most reliable and direct indicator for determining the nature and provenance of the Desert sediments.Methods:We quantitatively analyzed the rock and mineral composition of various landforms in different parts of the Kumtagh Desert,including graben valley terrace,marginal platform,feathery dune in the northern region,as well as diluvial platform,dry riverbed,marginal dune and interdune in the southern region.For the first time in the Kumtagh Desert research history,we employed lithology microscopy identification methods using a large number of multiple samples to obtain results.Results:The findings reveal that there is a diverse range of fine gravel and coarse sand debris types present in the Kumtagh Desert.These include three major classes(igneous rock,metamorphic rock and sedimentary rock),14 third-grade classes and 121 fifth-grade rocks.The predominant lithologies consist mainly of middle—acid effusive rocks and regional metamorphic rocks such as rhyolite,felsite,andesite,trachyte,quartzite and quartzitic rock.Whether it is a rock or a mineral is closely related to the size of the sand particles,about>90%of the gravel and 50%to 90%of the coarse sand are rock debris.The maximum lithology species is found at the grain size of 1.0mm,and the finer the sand grain,the higher the content of detrite minerals.This situation results in regional differences in lithology distribution in different regions and geomorphologic locations of the Desert due to the different grain size of the sand.Various major lithic fragments may exhibit different colour,with the dark particles are mainly composed of medium—acid extrusional rocks,while the light particles are mainly composed of quartzy rocks and felsic minerals,some of which hav

关 键 词：岩屑 物源 中酸性喷出岩 石英质岩 阿尔金山 库姆塔格沙漠 

分 类 号：P931.3[天文地球—自然地理学] P585