雪峰造山带南段靖州盆地成因性质及形成背景  

Nature, origin and tectonic setting of Jinzhou basin in the south segment of Xuefeng orogen

作　　者：柏道远 钟响 贾朋远 熊雄 黄文义 

机构地区：[1]湖南省地质调查院,湖南长沙410016

出　　处：《中国地质》2013年第4期1079-1091,共13页Geology in China

基　　金：中国地质调查局"湖南1:25万武冈市和永州市幅区调修测"项目(1212011120793);"中国地质构造区划综合研究与区域地质志修编"项目(1212010811032);中上扬子及邻区重点盆地地质地球物理综合调查(1212011120967)联合资助

摘　　要：靖州盆地是位于雪峰构造带南段的一个NE向晚三叠世—中侏罗世小型陆相盆地,前人研究提出其为NNE向溆浦—靖州大断裂左行走滑形成的拉分伸展盆地。本文对靖州盆地构造特征、T3—J2沉积和原型盆地特征等进行了系统研究,在此基础上提出该盆地实为挤压类前陆盆地,主要依据有:①沉积物高成熟度以及残留盆地边界与盆地周缘先期地质界线总体协调一致,说明盆地沉积时为挤压挠曲作用下形成的低缓洼地;②沉积物高成熟度和远源特征,指示盆地形成于相对稳定构造环境;③盆地北端T3—J1沉积空间由岩层弯曲下凹提供;沉积物产状变化指示J2盆地受到NW向挤压并产生持续褶皱变形;沉积物特征指示沉积环境西浅东深,进一步暗示J2盆地发展受控于NW向挤压与东缘逆冲块体的重力载荷;④盆缘伸展断裂少见,因挤压形成的小型走滑断裂、逆断裂、共轭剪节理等则多见;⑤从溆浦—靖州断裂走向偏转情况来看,该断裂左行走滑时靖州盆地所处部位应为挤压区而非拉张区。据盆地沉积和构造特征及区域大地构造演化背景,盆地的形成主要与晚三叠世—早侏罗世区域SN向挤压、中侏罗世区域NWW向挤压和NNE向左行走滑有关。Jinzh ou basin is a small NE-trending Late Triassic-Middle Jurassic continental basin in the south segment of Xuefeng orogen.Previous researchers held that the basin is a pull-apart extensional basin related to dextral strike-slipping of NNE-trending Xupu-Jinzhou fault.The authors studied the tectonic characteristics,sedimentary features and proto-basin of Late Triassic-Middle Jurassic Jinzhou basin and,on such a basis,brought forward the opinion that the basin is a compressional quasi-foreland basin according to evidence as follows ： ① High maturity of the deposits and the harmony of the basin boundary with surrounding older geological boundary indicates that the basin is a compressional low depression.② High component maturity and far-resource features of the deposits suggest that the basin was formed in a stable tectonic setting.③ The sedimentary space of Upper Triassic-Lower Jurassic strata in the northern basin was formed from rocks bending.The attitude changes of rocks indicate that the basin was NW-compressed and folded in Middle Jurassic.Sedimentary features show that there existed shallow-and deep-water environment in the west and the east of the basin,respectively,which implies that the basin was controlled by gravity load of east peripheral thrust block.④ In adjacent areas of the basin,there occur a few extensional faults and a lot of small strike-slip faults,thrust faults and conjugated shear joints related to the compression.⑤ According to the strike deflexion of the fault,Jinzhou basin was situated in a compressional area instead of an extensional area when Xupu-Jinzhou fault experienced dextral strike-slipping action.Based on the sedimentary and tectonic characteristics of Jinzhou basin and the regional tectonic setting,the authors hold that the basin was related mainly to regional S-N-compression during Late Triassic-Early Jurassic period,and related to NWW-compression and NNE-trending dextral strike-slipping during Middle Jurassic period.

关 键 词：类前陆盆地 挤压 走滑 晚三叠世—中侏罗世 靖州盆地 

分 类 号：P618.13[天文地球—矿床学]