黔中开阳地区南华系澄江组古环境演化及意义  

Paleo-environmental evolution of the Chengjiang Formation, Nanhuan System, in Kaiyang area, Central Guizhou, and its significance

作　　者：吴文明[1,2,3] 徐世林 杨瑞东[1] 王泽鹏[2,3] 刘建中[3,4] 刘松 王大福 吴小红[2] 万大学[2] 潘启权 张丞[2] WU Wenming;XU Shilin;YANG Ruidong;WANG Zepeng;LIU Jianzhong;LIU Song;WANG Dafu;WU Xiaohong;WAN Daxue;PAN Qiquan;ZHANG Cheng(College of Resource and Environmental Engineering,Guizhou University,Guiyang,550025;Geological Team,Bureau of Geology and Mineral Exploration and Development Guizhou Province,Guiyang,550018;Engineering Technology Innovation Center of Mineral Resources Explorations in Bedrock Zones,Ministry of Natural Resources,Guiyang,550081;Bureau of Geology and Mineral Exploration and Derelopment Guizhou Province,Guiyang,550001)

机构地区：[1]贵州大学资源与环境工程学院,贵阳550025 [2]贵州省地质矿产勘查开发局105地质大队,贵阳550018 [3]自然资源部基岩区矿产资源勘查工程技术创新中心,贵阳550081 [4]贵州省地质矿产勘查开发局,贵阳550001

出　　处：《地质论评》2020年第2期276-288,共13页Geological Review

基　　金：国家自然科学基金资助项目(编号:U1812402.41890841,41862002);贵州省科技厅项目(编号:黔科合平台人才[2018]5613);中国地质调查局项目(编号:1212010000150017-77,1212010000160901-34);贵州省地质矿产勘查开发局地质科研项目(编号:黔地矿办发[2016]10、11号)的成果。

摘　　要：为查明贵州开阳极乐南华系澄江组的沉积环境演化过程、物质来源。对开阳磷矿极乐矿段南华系澄江组剖面进行详细的野外考察,并开展沉积学、矿物学、主量、微量和稀土元素地球化学特征研究。结果表明:澄江组岩样SiO2含量为65.56%~78.45%,结合岩矿鉴定结果认为岩性主要为石英岩屑砂岩;其Al2O3/SiO2值和TiO2含量自下而上呈逐渐减小趋势;其Sr/Cu值平均为13.15,显示为干旱炎热气候;其沉积环境参数主要指标Th/U>2,V/Cr<2,δCe>1,δEu<1,均显示澄江组水体为氧化环境。∑REE为152.28~266.23μg/g,呈轻稀土富集,重稀土亏损,其配分模式与青白口系清水江组一致。综合认为:澄江组整套岩层水平层理发育,表明沉积区水体相对安静,总体为湖相沉积。其早至中-晚期水体深度由深变浅,至末期为浅滩环境。沉积物质可能来源于青白口系清水江组。沉积期间的古气候环境为干旱炎热,水体盐度自早到晚期持续上升,总体为氧化环境。澄江时期沉积的厚大泥沙建造,为后期陡山沱期形成无障壁浅滩缓坡相环境提供了物质基础。Objectives: Objectives: This study aimed to ascertain the sedimentary environmental evolution process and material source of the Chengjiang Formation,Nanhuan System(≈ Cryogenian System),in Jile,Kaiyang County,Central Guizhou Province.Methods: A detailed field investigation was conducted on the profile of the Chengjiang Formation profile of Nanhuan System,in Jile,Kaiyang.The sedimentology,mineralogy and geochemical characteristics of major,trace and rare earth elements was used.Results: The SiO2 contents of the samples from the Chengjiang Formation ranged from 65.56% to 78.45%,with an mean of 71.11%.The lithology of this formation is mostly quartz lithic sandstone based on the results of rock-mineral identification.Its ratio of Al2O3 to SiO2 and TiO2 contents showed a gradually decreasing trend from the bottom to the top for the whole profile.The average of Sr/Cu ratio was 13.15,showing a dry and hot climate.The major parameters for sedimentary environment(e.g.,Th/U > 2,V/Cr < 2,δCe > 1,δEu < 1,U/Th > 1)indicating that the environment in which the Chengjiang Formation was formed was an oxidizing environment.The concentrations of ∑REE in rock samples ranged from 152.28 to 266.23 μg/g,indicating that the enrichment of light rare earth elements and the loss of heavy rare earth elements.Further,its distribution patterns are consistent with those of the Qingshuijiang Formation(Qingbaikou System).Conclusions: The horizontal stratification of the Chengjiang Formation indicates the water body in the sedimentary area is relatively quiet,and the complete set of rock formations of the Chenjiang Formation is generally lacustrine.From early stage to late stage,the water depth changes from deep to shallow,and then to the late stage,the sedimentary environment of the Chenjing Formation becomes a shoal environment.The sedimentary materials may come from the Qingshuijiang Formation,Qingbaikou System.The climate during the deposition was dry and hot.The salinity of the water continued to rise from early to late stage,and the

关 键 词：黔中 澄江组 沉积环境 物质来源 

分 类 号：P532[天文地球—古生物学与地层学] P619.2[天文地球—地质学]