贵州铜仁地区南华系铁丝坳组—南沱组沉积环境及古气候演变  

Sedimentary environment and paleoclimate research of Tiesi′ao Formation-Nantuo Formation in Tongren,Guizhou

作　　者：唐婷婷 牟军 王安华 强希润 TANG Tingting;MOU Jun;WANG Anhua;QIANG Xirun(Guizhou Institute of Geological Survey,Guiyang 550081,China)

机构地区：[1]贵州省地质调查院

出　　处：《贵州科学》2019年第6期67-73,共7页Guizhou Science

基　　金：贵州省地矿局青年地质科学研究项目《荔波—独山地区晚二叠世成煤古地理环境研究》(黔地矿科合[2015]24号);1∶5万漾头司、万山特区、瓦屋、新晃幅区域地质调查项目(项目编码:12120114068201)联合资助

摘　　要：在野外路线和剖面观察实测的基础上,对铜仁地区南华系沉积环境进行了讨论,并通过南华系碎屑岩的化学成分研究对铁丝坳组—南沱组古气候进行了分析。其中铁丝坳组沉积环境为冰水浅海环境沉积,由向上变细的退积型副层序组成低水位体系域;大塘坡组共分为两段,第一段为局限边缘盆地沉积,主体由向上变深的退积型副层序组成海侵体系,第二段为浅水陆棚沉积,其中泥质逐渐减少,砂质含量逐渐增多,为高水位体系域;南沱组为海洋冰碛砾岩沉积,为不显层理的变余冰碛砾岩、冰碛砂砾岩、含砾不等粒砂岩组成。对碎屑岩的化学成分结果分析表明:铁丝坳组和南沱组具有低的CIA指数和Ti/Al比值,说明该时期主要为寒冷、干燥的气候环境,化学风化程度低,物源供给相对降低,具有较低的沉积速率,为冰期特点。南沱组的CIA指数和Ti/Al比值相对较高,表明该时期主要以温暖湿润气候为主,化学风化程度较高,物源供应和沉积速率相对较高,为间冰期特点。In this paper we discussed the sedimentary environment of Nanhua System in Tongren area based on field survey and section observation,and analyzed the paleoclimate of Tiesi′ao Formation-Nantuo Formation by the change of geochemical variations.The depositional environment of Tiesi′ao Formation is shallow sea environment constituted by retrograding sequence,which is the LST.The fist period of Datangpo Formation is the edge of restricted basin constituted by retrograding sequence,which is the TST.The shale reduced and sand increased gradually upwards in second period of Datangpo Formation,which is HST.Relatively low values of chemical index of alteration(CIA)and Ti/Al of Tiesi′ao Formation and Nantuo Formation suggested cold,dry climate with low source supply and glaciation period.In contrast,Datangpo formation had high values of CIA and Ti/Al,indicating warm,humid climate with high source supply and interglaciation period.

关 键 词：铜仁 南华系 铁丝坳组—南沱组 沉积环境 古气候 

分 类 号：P539[天文地球—古生物学与地层学]