贵州瓮安地区北斗山矿区寒武系牛蹄塘组的特征  

Features of Cambrian Niutitang Formation in the Beidoushan ore district,Weng'an County,Guizhou Province

作　　者：庞艳春[1] 林丽[1] 朱利东[1] 周玉华[2] 任才云 

机构地区：[1]成都理工大学沉积地质研究院,四川成都610059 [2]贵州瓮福磷矿,贵州福泉550508

出　　处：《地质通报》2011年第8期1245-1250,共6页Geological Bulletin of China

基　　金：国家自然科学基金项目<古热水成矿区生物群面貌及其特殊性>(批准号:40472013);教育部高等学校博士学科点专项科研基金项目<寒武系牛蹄塘组热水沉积中的微生物群研究>(编号:20095122110013);贵州瓮福大信北斗山磷矿项目;中国石油化工股份有限公司项目(编号:G0800-06-ZS-319)

摘　　要：瓮安大信北斗山矿区牛蹄塘组出露普遍,厚度较薄,明显分为2段。下段称上磷矿段,以磷质岩或磷块岩为主,沉积结构以内碎屑结构为主,内碎屑成分主要为磷质砂屑,可见黄铁矿和海绿石;岩层具有透镜状层理、水平层理、块状层理、磷质结核体等沉积构造。上段称黑色页岩段,以黑色页岩为主,沉积结构以泥质结构为主;普遍发育水平层理和较大个体的磷结核体。黑色页岩段底部普遍含镍钼钒多金属层;下部含黄铁矿纹层或结核,中部出现碳酸盐结核。对牛蹄塘组的地层特征和岩石学特征分析表明,本区牛蹄塘组为水体较深的缺氧沉积,显示为海平面上升期的海侵层,上磷矿段沉积时为动力较强的滨海至浅海陆棚相环境,黑色页岩段沉积时为水动力较弱的陆棚边缘盆地相环境,多金属层位于最大海泛面处。Niutitang Formation has a wide distribution in the Beidoushan ore deposit,Weng＇an County,Guizhou Province.It is small in thickness and can be divided into two members.The Lower Member of the Niutitang Formation is described as upper phosphorite member which has phosphorite or phosphate rocks.It has clastic texture in which the particles have some phosphorite scraps,pyrites or glauconites.Its sedimentary structures include lenticular bedding,horizontal bedding,massive bedding and phosphate concretion.The Upper Member of the Niutitang Formation is described as black shale member.It has clay structure.Its sedimentary structures include horizontal bedding and bigger phosphate concretion.The bottom of the black shale member has a polymetallic layer with such elements as nickel,molybdenum and vanadium.The lower part of the black shale member has pyrite lamina or concretion.The middle part has carbonate concretion.The characteristics of Niutitang Formation show a relatively deep water and anoxic sedimentary environment,which represents a transgression layer.The early sedimentary environment of Niutitang Formation was a coastal-shallow continental shelf with strong hydrodynamic force,the late sedimentary environment was a deeper water continental shelf with weak hydrodynamic force,and the polymetallic layer was formed at the biggest flooding surface.

关 键 词：贵州瓮安地区 牛蹄塘组 特征 沉积相 

分 类 号：P534.41[天文地球—古生物学与地层学]