摘要
为分析贵州遵义二叠纪锰矿的沉积环境,对谢家坝锰矿床进行常量元素、微量和稀土元素地球化学研究。研究认为:谢家坝锰矿赋存于茅口组顶部含锰岩系中,分为下矿层豆状、角砾状菱锰矿、似层状菱锰矿,以及上矿层碎屑状、块状菱锰矿的二元结构矿石类型组合,可广泛代表遵义锰矿的矿石特征。谢家坝锰矿上下矿层之间主量元素和稀土元素含量差异较大,常量元素SiO_(2)、TiO_(2)、S、Fe_(2)O_(3)含量上矿层均大于下矿层,MnO、MgO与Al_(2)O_(3)之间均呈负相关关系;上矿层Fe/Mn值较高,属高Fe、低P型锰矿,而下矿层Fe/Mn值较低,属中低Fe、低P型锰矿。上矿层稀土元素PAAS标准化配分后呈现较明显的重稀土亏损、弱的轻稀土富集、右倾配分的特征,具有弱的Ce正异常,类似海底铁锰结核稀土元素特征;下矿层呈现弱的中稀土富集,轻、重稀土亏损,弱的帽式分配特征,具明显的Ce负异常,类似典型深部海水沉积稀土元素特征。微量元素Th/U、Ni/Co、V/Cr、V/(V+Ni)、AU等沉积环境古氧相分析指标和稀土元素PAAS标准化配分模式指示,谢家坝锰矿下矿层是在贫氧-厌氧条件下Mn^(2+)与CO_(3)^(2-)直接形成菱锰矿,上矿层在常氧-贫氧环境下Mn^(3+)、Mn^(4+)以氧化物或氢氧化物形式沉淀。
This work conducted major elements,trace elements and rare earth elements geochemistry on the Xiajiaba manganese deposit in order to analyze the sedimentary environments of the Permian manganese deposits in Zunyi of Guizhou Province.Results show that the Xiejiaba manganese ores are hosted in the manganese rock series at the top of Maokou Formation.The ores can be divided into two combinations of ore types,i.e.,the lower bean,baccalciform rhombozite and layered rhombozite,and the upper detrital and massive rhombozite,which can generally represent the ore characteristics of Zunyi manganese ores.The content of major elements and rare earth elements differs greatly between the upper and lower ore layers of the Xiejiaba manganese deposit.The content of major elements SiO_(2),TiO_(2),S and Fe_(2)O_(3) in the upper layer is greater than that of the lower layer,and a negative correlation exists between MnO,MgO content and Al_(2)O_(3) content.The upper ore layer contains higher Fe/Mn value,belonging to the high-Fe and low-P type manganese ores,while the lower ore layer possesses low Fe/Mn value,belonging to the medium-low Fe and low-P type manganese ores.The standardized partition of PAAS indicates that,the rare-earth elements in the upper ore layer show obvious HREE depletion,weak LREE enrichment and right-inclined partition,with weak positive Ce anomalies,which is similar to the rare earth elements characteristics of iron manganese nodules in the seabed.The lower layer shows weak enrichment of medium rare earth,depletion of LREE and HREE,weak cap-type distribution and obvious negative Ce anomalies,which is similar to typical rare earth elements in deep seawater deposits.Suggested by trace elements Th/U,Ni/Co,V/Cr,V/(V+Ni),AU and other paleooxygen facies analysis indexes for sedimentary environments and the standardized partition pattern of rare earth elements PAAS,the lower layer of the Xiejiaba manganese deposit was directly formed by Mn^(2+)and CO32-under oxygen-poor and anaerobic conditions.Mn3+and Mn4+were precipitated in the form of oxides or hydroxides in the upper layer under normal oxygen-poor environments.
作者
陈登
肖亮
肖林
刘志臣
CHEN Deng;XIAO Liang;XIAO Lin;LIU Zhichen(102 Geological Brigade of Guizhou Bureau of Geology and Mineral Resources,Zunyi,Guizhou 563000;Technology Innovation Center of Mineral Resources Exploration Engineering in Bedrock Zone,Ministry of Natural Resources,Guiyang,Guizhou 550009;College of Resources and Environmental Engineering,Guizhou University,Guiyang,Guizhou 550025)
出处
《地质与勘探》
CAS
CSCD
北大核心
2023年第4期691-703,共13页
Geology and Exploration
基金
贵州战略找矿科技重大协同创新项目“贵州磷、锰、铝优势资源成矿规律与快速高效智慧化勘查技术研究及示范”(编号:黔科合战略找矿[2022]ZD003)
中国地调局贵州遵义锰矿整装勘查区矿产地质调查与找矿预测项目(编号:DD20190159-16)
贵州省地矿局(编号:黔地矿科合[2020]2号、黔地矿科合[2021]3号、黔地矿科合[2022]3号)
贵州省锰矿资源预测评价科技创新人才团队(编号:黔科合平台人才[2018]5618)联合资助。
关键词
微量元素
沉积环境
谢家坝锰矿
古氧相
遵义
贵州
trace elements
sedimentary environment
Xiejiaba manganese deposit
paleo-oxygen facies
Zunyi
Guizhou Province
