滇中盆地石炭纪—中二叠世沉积-古地理特征与富Li黏土岩物源分析  

Carboniferous-Middle Permian sedimentary-paleogeographic environment and source of the lithium-rich claystones in the Central Yunnan basin,SW China

作　　者：张佳慧 闫臻[2] 薛传东[1] 俞良军[3] 魏爱英[1] 付长垒[2] 王维 王宇 周红琳 ZHANG Jiahui;YAN Zhen;XUE Chuandong;YU Liangjun;WEI Aiying;FU Changlei;WANG Wei;WANG Yu;ZHOU Honglin(Department of Earth Sciences,Kunming University of Science and Technology,Kunming,Yunnan 650093,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]昆明理工大学地球科学系,云南昆明650093 [2]中国地质科学院地质研究所,北京100037 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《地质学报》2025年第4期1120-1133,共14页Acta Geologica Sinica

基　　金：国家重点研发计划课题(编号2021YFC2901901,2022YFC2903401);国家自然科学基金项目(编号41922022,42163007,41373049)联合资助的成果。

摘　　要：滇中盆地石炭系—中二叠统产有铝土矿、煤、方解石矿、石灰岩等矿产,并伴生大量的富Li黏土岩,其成矿环境受沉积环境及其构造古地理时空演变的制约。系统的野外调查研究显示,滇中盆地石炭系是一套形成于滨岸潮坪-潟湖环境的陆源碎屑岩和碳酸盐岩组合,下—中二叠统则为潟湖-潮坪-开阔台地相沉积组合。其中,下石炭统大塘组主体表现为潮坪环境的碳酸盐岩夹泥页岩组合,潟湖相沉积仅出现在牛首山古陆周缘;上石炭统威宁组和马平组仅在牛首山古陆旁侧零星出露,为滨岸潮坪相沉积;下二叠统倒石头组是一套细粒陆源碎屑沉积组合,局部夹少量灰岩透镜体,产有铝土矿、煤矿及富Li黏土岩,形成于潮坪-潟湖环境;中二叠统栖霞组和茅口组为藻屑灰岩、白云质亮晶生屑灰岩及中—粗晶白云岩组合,为开阔台地相沉积。空间上,大塘组和倒石头组厚度变化较大,总体具有向南地层厚度变薄且煤层和铝土质岩层数减少的趋势,显示水体向南逐渐变浅;栖霞组和茅口组向北的出露面积和厚度增大,与古水流分析揭示的早、中二叠世滇中地区具有东南高、西北低的古地貌特征相一致。这说明,滇中盆地东南侧的牛首山古隆起是该盆地倒石头组的主要沉积物供给区。岩石地球化学资料显示,倒石头组为富Al和Li的黏土岩,并受物源区风化强度和沉积环境的控制,当Al_(2)O_(3)<55%、Al_(2)O_(3)/SiO_(2)<3时,Li与Al_(2)O_(3)含量呈正相关关系,其余均呈负相关关系。区域资料分析显示,牛首山古隆起以前寒武纪中—基性火山岩和相关沉积岩为主,在早石炭世—中二叠世受古特提斯洋持续打开的影响发生区域隆升,导致其火山-沉积地层发生风化剥蚀并伴随区域火山活动,从而成为其旁侧的滇中盆地铝土矿和富Li黏土岩的重要来源。The Carboniferous-Middle Permian sedimentary sequences of the Central Yunnan basin,SW China,are rich in bauxite,coal,calcite,limestone,and other types of ore deposits associated with numerous lithium-rich claystones.Understanding the genesis of these ore deposits necessitates a comprehensive analysis of the spatial-temporal evolution of the sedimentary environments and the basin's paleogeography.Systematic field investigations demonstrate that Carboniferous sedimentation in the Central Yunnan basin was dominated by terrigenous clastic and carbonate rocks deposited in a littoral tidal flat-lagoon environment.In contrast,the Lower-Middle Permian sedimentary rocks were mainly deposited in a lagoon-tidal flat-open platform environment.The Lower Carboniferous Datang Formation is characterized by carbonates with muddy shale interlayers,indicating deposition in a tidal flat environment.Lagoon deposition was restricted to areas adjacent to the Niushoushan paleo-uplift.The Middle Carboniferous Weining and Maping formations represent littoral-tidal flat deposits,sporadically exposed around this uplift.The Lower Permian Daoshitou Formation,composed of fine-grained terrigenous clastic rocks with minor limestone lenses,reflects deposition in a tidal flat-lagoon setting.This formation is particularly significant as it hosts the bauxite,coal ore deposits,and lithium-rich claystones.The Middle Permian Qixia and Maokou formations consist of algal clastic limestone,dolomitic leucoblastic bioclastic limestone,and medium-to coarse-grained dolomite,indicating an open-platform depositional environment.A distinct spatial pattern is observed in the thickness of the Datang and Daoshitou formations,with a pronounced thinning trend towards the south.This,coupled with a decrease in the number of coal and bauxite layers southward,suggests a gradual shallowing of seawater depth towards the south,bringing the deposits closer to their source area.Conversely,the Qixia and Maokou formations exhibit a widespread exposure in the north,with their th

关 键 词：石炭纪—中二叠世 沉积-古地理环境 物源分析 富Li黏土岩 牛首山古陆 滇中盆地 

分 类 号：P618.13[天文地球—矿床学]