陕西凤太晚古生代拉分盆地动力学与金——多金属成矿  

Dynamics of Late Paleozoic Pull-apart Basin and Its Relationship with Mineralization of Gold-polymetallic Deposits in Fengxian-Taibai Counties,Shaanxi Province,China

作　　者：方维萱[1,2,3] 黄转盈 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]中色地科矿产勘查股份有限公司,北京100012 [3]北京矿产地质研究院,北京100012

出　　处：《沉积学报》2012年第3期405-421,共17页Acta Sedimentologica Sinica

基　　金：国家自然科学重点基金资助项目(批准号:41030423);科技部转制科研院所专项资金项目联合资助(批准号:2011EG115022)资助

摘　　要：采用沉积盆地构造—古地理位置恢复重建和构造—岩相学等新方法研究认为,凤太晚古生代沉积盆地属于受板块斜向俯冲碰撞动力学控制下的拉分盆地。在中泥盆世初期,凤太沉积盆地被周缘垂向基底隆起分隔,其成盆构造动力学主要受四组同生断层,晚古生代沉降中心和沉积中心不断发生迁移。中泥盆世中期在盆地北部形成了北西向沉降中心和沉积中心,晚泥盆世末期沉积盆地萎缩,沉降中心和沉积中心收缩于沉积盆地中心。石炭纪沉降中心和沉积中心从盆地中心迁移到盆地四周边缘的同生断裂带附近,在沉积盆地北侧边缘商丹带南侧,形成了石炭纪—早三叠世与俯冲消减带有关的楔状沉积充填体。在凤太拉分盆地中形成的近东西向、北北东向、近南北向和北西向网状同生断裂带系统共同控制了凤太泥盆纪拉分盆地形成与演化过程。其中,商丹带(西段)、礼县—凤县—凤镇—山阳同生断裂带(中段)和酒奠梁—镇安—板岩镇同生断裂带(西段)三个主控同生断裂带不但在泥盆纪期间对于凤太泥盆纪拉分盆地形成具有显著控制作用,而且石炭纪—早三叠世拉分盆地演化过程也具有十分重要的控制作用,石炭纪—早三叠世同生断裂带发生构造反转并控制了沉降中心和沉积中心。采用沉积盆地动力学和构造—岩相学等新方法研究认为,在凤太晚古生代拉分盆地具有分级特征,西部凤县二级盆地为金—多金属成矿集中区,东部太白二级盆地为金矿成矿集中区。在八方山—银母寺三级拉分盆地中,八方山和银母寺等多金属矿床与八卦庙超大型金矿床具有矿田尺度上成矿分带,主要由于三级盆地、同生断裂、热水沉积岩相和构造热流体叠加岩相控制了矿田和矿床尺度上金与多金属成矿分带。凤太拉分盆地北部和东部金矿矿源层和初步富集成矿形成主要与泥盆纪钠长�Fengxian-Taibai sedimentary basin could be the Paleozoic pull-apart basin which might be controlled by oblique-directed subduction and collision of the Qinling and Yangtze Plates based on new research methods,i.e.,re-construction and restoration of geotectonic-paleogeographic position and tectonic lithofacies.During the initial stage of the Middle Devonian period,Fengxian-Taibai sedimentary basin was enclosed and separated by marginal vertical base-uplifting,and dynamics of basin was controlled by four groups of synsedimentary faults,resulted in continual migrations of subsidence and sedimentary centers in the Late Paleozoic basin.During the middle stage of the Middle Devonian period,subsidence and sedimentary centers trending north-west-directed might be located in north part of Fengxian-Taibai basin while subsidence and sedimentary centers trending north-west-directed shrink in the center part of Fengxian-Taibai pull-apart basin during the Late Devonian period.However,the Carboniferous subsidence and sedimentary centers were migrated from the center to the zones of marginal syn-faults of Fengxian-Taibai pull-apart basin,and the Carboniferous to the Early Triassic wedge-shaped sediment-filling bodies related to zone of the plate subduction and collision was located at the southern part the Shangdan suture in the northern margin of Fengxian-Taibai pull-apart basin.Finally,formation and evolution of Fengxian-Taibai pull-apart basin might have been controlled by the NW-,NNE-,NS-and NW-trending synsedimentary faults in the Fengxian-Taibai Devonian pull-apart basin.The west part of Shangdan,the middle part of Lixian-Fengxian-Fengzhen-Shanyang,and the west part of Jiujianliang-Zhenan-Banyanzhen synsedimentary faults were of most important controls not only in the formation of the Fengxian-Taibai Devonian pull-apart basin but also in the evolution of the Carboniferous period to the Early Triassic pull-apart basin.Tectonic inversion of synsedimentary faults controlled subsidence and sedimentary centers during the evolut

关 键 词：拉分盆地 盆地动力学 构造—岩相学 热水沉积岩相 构造—热流体叠加岩相 

分 类 号：P512.2[天文地球—地质学]