重庆城口震旦系下统陡山沱组层序地层分析
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摘要
重庆城口震旦系下统陡山沱组共分两段,主要发育浅海陆棚沉积相,包括过渡相和滨外陆棚两个微相。对区内钻井剖面及露头剖面进行分析,识别出岩性岩相转换面、陡山沱组与观音崖组之间界面两种层序界面类型,将陡山沱组划分为4个Ⅱ型三级层序。其中层序1为陡山沱组第一段底部,层序2为陡山沱组第一段中部,层序3为陡山沱组第一段上部和第二段底部,层序4为自陡山沱组第二段下部至灯影组第一段底部中厚层状白云岩。基于浅海陆棚的背景,研究区陡山沱组第四次海平面广泛上升至最大海泛面滞后时段内,在深水、还原、偏碱性的浅海滨外陆棚环境下锰矿才开始聚集,且在高燕、修齐等锰矿区成为重要的开采矿床。
The lower Sinian Doushantuo Formation in Chengkou,Chongqing can be partitioned into two members,mainly developed neritic shelf sedimentary facies including transitional and offshore shelf two microfacies. After analysis of borehole section and outcrop section,two sequence boundary types of lithology,lithofacies transitional surface and interface between Doushantuo Formation and Guanyinya Formation,partitioned the Doushantuo Formation into 4 type II third-order sequences,in which,the sequence 1 is in the bottom part of first member,sequence 2 in the middle part of first member,sequence 3 in the upper part of first member,and bottom part of second member,sequence 4 from Doushantuo Formation second member lower part to the Dengying Formation first member bottom part medium thick stratified dolomite. Based on neritic shelf setting,study area Doushantuo Formation from the fourth sea level wide rise to maximum marine-flooding surface lag period,under deep water,reduction,alkalescent,neritic offshore shelf environment,and then the manganese ore accumulation just started,formed important mineable manganese ores in the Gaoyan,Xiuqi etc. areas.
The lower Sinian Doushantuo Formation in Chengkou,Chongqing can be partitioned into two members,mainly developed neritic shelf sedimentary facies including transitional and offshore shelf two microfacies. After analysis of borehole section and outcrop section,two sequence boundary types of lithology,lithofacies transitional surface and interface between Doushantuo Formation and Guanyinya Formation,partitioned the Doushantuo Formation into 4 type II third-order sequences,in which,the sequence 1 is in the bottom part of first member,sequence 2 in the middle part of first member,sequence 3 in the upper part of first member,and bottom part of second member,sequence 4 from Doushantuo Formation second member lower part to the Dengying Formation first member bottom part medium thick stratified dolomite. Based on neritic shelf setting,study area Doushantuo Formation from the fourth sea level wide rise to maximum marine-flooding surface lag period,under deep water,reduction,alkalescent,neritic offshore shelf environment,and then the manganese ore accumulation just started,formed important mineable manganese ores in the Gaoyan,Xiuqi etc. areas.
引文
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[2]Flint S S,Aitken J F&Hampson G. Application of sequence stratigraphy to coal-bearing coastal plain successions:implications for the UK coal measures[C]//Whateley M K G&Spears D A(eds). European coal geology. Geological Society,London,Special Publication,1995,82:1-16.
[3]邵龙义,陈家良,李瑞军,等.广西合山晚二叠世碳酸盐岩型煤系层序地层分析[J].沉积学报,2003,21(1):168-173.
[4]朱筱敏,康安,胡宗全,徐子远.柴达木盆地第四系层序地层特征与油气评价[J].石油勘探与开发,2002,29(1):56-60.
[5]姜在兴.沉积体系及层序地层学研究现状及发展趋势[J].石油与天然气地质,2010,31(5):525-541.
[6]向杰,陈建平,张莹.中国锰矿资源现状与潜力分析[J].地质学刊,2013,37(3):382-386.
[7]万平益,罗锋.重庆市城口锰矿地质特征与成因及成矿远景分析[J].中国锰业,2000,18(3):5-8.
[8]赵东旭.川北高燕锰矿的锰质岩类型和生物成矿作用[J].岩石学报,1994,10(2):171-183.
[9]张俊,朱明忠,李余生,等.重庆高燕含锰岩系地质地球化学特征及意义[J].金属矿山,2015(1):86-89.