柴北缘鱼卡地区路乐河组砂岩岩石学及碎屑锆石稀土元素地球化学特征研究  

Petrological Characteristics of The Lulehe Formation Sandstone and Geochemical Characteristics of Detrital Zircon Rare Earth Elements in Yuqia Area,Northern Margin of Qaidam Basin

作　　者：黄广文[1,2] 潘家永 黄广楠[3] 吴德海 丛殿阁[5] 闵壮 孙达 HUANG Guang-wen;PAN Jia-yong;HUANG Guang-nan;WU De-hai;CONG Dian-ge;MIN Zhuang;SUN Da(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Qinghai Province Key Laboratory of Geological Process and Mineral Resources of Northern Qinghai-Tibet Plateau,Xining 810012,China;No.105 Exploration Team,Qinghai Bureau of Coal Geological Exploration,Xining 810007,China;School of Resources,Environment and Jewelry,Jiangxi College of Applied Technology,Ganzhou 341000,China;Geological Engineering Department,Qinghai University,Xining 810016,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]青海省青藏高原北部地质过程与矿产资源重点实验室,青海西宁810012 [3]青海煤炭地质105勘探队,青海西宁810007 [4]江西应用技术职业学院资源环境与珠宝学院,江西赣州341000 [5]青海大学地质工程系,青海西宁810016

出　　处：《稀土》2021年第3期21-33,共13页Chinese Rare Earths

基　　金：国家自然科学基金项目(41772066,41902075,42002091);核资源与环境国家重点实验室开放基金项目(2020NRE03);青海省青藏高原北部地质过程与矿产资源重点实验室资助项目(2019-KY-04);青海省科技计划自然科学基金项目(2019-ZJ-955Q)。

摘　　要：在详细观察描述砂岩宏观特征的基础上,利用偏光显微镜和LA-ICP-MS对鱼卡地区路乐河组含砾砂岩进行了碎屑骨架组分及碎屑锆石原位微区稀土元素分析,初步解析了岩相学、稀土元素特征及物源等信息。结果表明,路乐河组出露砂岩以含砾长石石英砂岩、含砾岩屑砂岩为主,且岩石成分成熟度和结构成熟度低,发育有一系列绿泥石化、碳酸盐化等后生蚀变。依据QFL与QmFLt图解,结合区域地质背景,认为区内砂岩物源为一套相对稳定的岩屑再旋回造山带区向过渡再旋回造山带、再向混合型再旋回造山带区的演变过程;不同构造阶段的碎屑锆石从老到新(吕梁期→印支海西期)稀土元素标准化配分曲线呈现相类似的左倾特征,具Eu的弱负异常和明显Ce的正异常特征,为典型岩浆锆石特征。此外,稀土元素总量呈现逐渐升高的趋势,稀土元素标准化配分曲线也呈现逐渐升高的趋势。综合推断其碎屑物源来自于研究区北东部达肯达坂山和南部绿梁山。Based on the detailed observation and description of the macroscopic characteristics of the sandstone, we use polarizing microscope to analyze the detrital skeleton components and use LA-ICP-MS to carry out in-situ microzone rare earth analysis of detrital zircons of the pebble-bearing sandstone exposed in the Lulehe Formation in Yuqia area, in order to explore the petrographic, rare earth element characteristics and material source. The results show that the outcropping sandstone in the Lulehe Formation is mainly gravel-bearing arkose quartz sandstone and gravel-bearing lithic sandstone, with the low maturity of rock composition and structure, and there are a series of post-alteration phenomena such as chloritization. Based on the QFL and QmFLt diagrams and combined with the regional geological background, we concluded that the sandstone source is a relatively stable debris recirculating orogenic belt, which is an evolution process from the transition recirculating orogenic belt to the mixed recirculating orogenic belt. The chondrite-normalized REE distribution patterns of rare earth elements of detrital zircon in different construction phase from old to new(Lvliang period to Indosinian-Hercynian) have similar left-leaning type characteristics, accompanied by a weak negative Eu anomaly and Ce significantly positive anomaly, showing a typical magmatic zircon feature. Besides, the amount of rare earth elements has a rising trend, and the chondrite-normalized REE distribution patterns also present a rising trend. It is preliminarily concluded that the material source may be from Dakendaban Mountain in the north east and Lvliang Mountain in the south of the studied area.

关 键 词：碎屑锆石 稀土元素 物源 路乐河组 鱼卡 

分 类 号：P588.21[天文地球—岩石学]