湖北恩施硒富集区中二叠世孤峰组露头层序地层研究  

Sequence stratigraphy of Middle Permian Gufeng Formation from selenium-rich area in Enshi, Southwestern Hubei

作　　者：石先滨 翁茂芝 罗红 许露露 龚志愚 赵雪松 段先锋 

机构地区：[1]湖北省地质调查院,武汉430034

出　　处：《华南地质与矿产》2016年第1期1-9,共9页Geology and Mineral Resources of South China

基　　金：中国地质调查局国土资源大调查项目"湖北1:5万三岔幅;红土溪幅;官店口幅;万寨幅;椿木营幅;下坪幅区域地质调查"(12120113061800)资助

摘　　要：通过实测地层剖面的精细研究,结合微量元素地球化学分析,探讨了恩施地区富硒地层中二叠世孤峰组层序界面识别、层序划分与对比及其对硒元素空间分布的影响。研究区中二叠世孤峰组可总结为4种基本层序类型,分别为炭硅质页岩-炭硅质岩、炭硅质页岩-炭硅质岩夹灰岩透镜体、炭硅质岩-含炭泥晶灰岩和炭硅质岩-含炭细晶白云岩;识别出3个层序界面,其中孤峰组与茅口组接触界线处为Ⅲ型层序界面,孤峰组中部的岩性结构转换面为Ⅱ型层序界面,龙潭组与孤峰组接触界线处为Ⅰ型层序界面;划分了2个三级层序(SQ1、SQ2)。通过层序对比分析,随着海侵作用的持续发展,区域上层序内部结构及基本层序类型分异明显,沉积古地理格局表现为南浅北深的特征;通过层序地层与硒异常耦合关系分析,发现了孤峰组内部Ⅱ型层序界面附近具高硒异常特征,确立了新的找矿标志。By researching the stratigraphic section, combined with trace element analysis, sequence boundary,sequence division and comparison, in addition the influence of the spatial distribution of selenium of selenium-rich Middle Permian Gufeng Formation was studied. Middle Permian Gufeng Formation of the study areacan be concluded as four types of basic sequence, which were silica carbonaceous shale-silica carbonaceousrock, silica carbonaceous shale-silica carbonaceous rock inter-calated with limestone lenses, silica carbonaceous rock-micrite with carbon, and silica carbonaceous rock-fine crystalline dolomite with carbon. Threetypes of sequence boundary were identified, in which the boundary of Maokou Formation and Gufeng Formation was Ⅲ-type sequence boundary, and the transition surface of rock character in middle of Gufeng formation was Ⅱ-type sequence boundary, in addition, the boundary of Longtan Formation and Gufeng Formationwas Ⅰ-type sequence boundary, and two types of Three-grade Sequence Interface（SQ1,SQ2）was subdivided.Through comparison analysis, sequence-internal structures and types of basic sequence with transgressions ofthe area was obvious difference, and the sedimentation paleogeographic feature was formed in shallow waterin the southern side and deep water in northern side. Through analysis of the coupling relationship of sequence stratigraphy and selenium anomaly, high selenium anomalous character was discovered near Ⅱ-typesequence boundary in Gufeng Formation, that the new prospecting criteria was established.

关 键 词：硒元素 孤峰组 层序地层 鄂西恩施地区 

分 类 号：P534.46[天文地球—古生物学与地层学] P618.76[天文地球—地质学]