滇中盆地南缘富锂黏土岩地球化学特征及沉积环境初探  

Geochemical Characteristics and Sedimentary Environment of Li-rich Clay Rocks at the Southern Margin of the Central Yunnan Basin

作　　者：贾永斌 于文修[1] 温汉捷[2,3] 罗重光 杨光树 杨洋[2] 崔燚 JIA YongBin;YU WenXiu;WEN HanJie;LUO ChongGuang;YANG GuangShu;YANG Yang;CUI Yi(Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093 [2]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵阳550081 [3]中国科学院大学地球与行星科学学院,北京100049 [4]东华理工大学核资源与环境国家重点实验室,南昌330013

出　　处：《沉积学报》2023年第1期170-182,共13页Acta Sedimentologica Sinica

基　　金：国家重点研发计划(2017YFC0602500)。

摘　　要：沉积岩中的微量元素对沉积环境变化有较高的敏感度,是研究古沉积环境的有效手段。滇中盆地倒石头组是一套富锂的黏土岩地层,其古环境的研究对恢复该时期盆地沉积格局和锂元素富集具有重要意义。基于滇中盆地倒石头组两个典型钻孔样品详细的地球化学研究,探讨了倒石头组富锂黏土岩形成时的沉积环境及其对锂元素富集的影响。研究结果表明:所有样品Sr、Ga元素含量及Sr/Ba值指示研究区古水体介质为淡水陆相沉积环境;其δU值介于0.51~1.63,U/Th值介于0.11~1.49,V/(V+Ni)值介于0.48~0.86,V/Cr值介于0.45~1.24,同时在U_((EF))-Mo_((EF))协变模式图中,样品数据均未落在缺氧和硫化区域,表明研究区富锂黏土岩的沉积环境为氧化—弱还原环境;且样品Sr/Cu比值介于0.69~4.87,CIA值介于86.3~99.66,XRD全岩黏土矿物分析显示高岭石为主要的黏土矿物,表明富锂黏土岩在形成过程中处于温暖潮湿的沉积环境并伴随较为强烈的化学风化作用。Trace elements in sedimentary rocks are highly sensitive to changes of sedimentary environment,and are an effective indicator of the paleosedimentary environment.The inverted rock formation in the Central Yunnan Basin is a set of claystone strata rich in lithium.The study of its paleoenvironment is of great significance for reconstructing the basin sedimentary pattern and lithium enrichment in this period.In this study a detailed geochemical investigation was carried out on two typical borehole samples from the formation,aiming to explore the sedimentary environment and influences on the lithium enrichment and provide a reference for future studies of lithium resources in the region.The Sr,Ga and Sr/Ba values indicate that the paleo-water medium in the study area was a freshwater continental sedi-mentary environment.TheδU values in all samples were in the range 0.51-1.63;U/Th values were 0.11-1.49;V/(V+Ni)values were 0.48-0.86;and V/Cr values were 0.45-1.24.Sample data in the U_((EF))-Mo_((EF))covariant model lay out-side the anoxic and sulfurized areas,indicating an oxygen-weak reducing sedimentary environment for the lithiumrich claystone.The Sr/Cu ratios of all samples were 0.69-4.87,with CIA values 86.3-99.66.Whole-rock XRD analy-sis showed kaolinite as the main clay mineral,indicating that the lithium-enriched claystone formed in a warm,hu-mid sedimentary environment accompanied by strong chemical weathering.

关 键 词：氧化还原条件 古盐度 古气候 黏土岩 滇中盆地 

分 类 号：P588.2[天文地球—岩石学]