陕西凤太拉分盆地构造变形样式与动力学及金-多金属成矿  

Tectonic deformation styles and dynamics of gold-polymetallic deposits in Fengtai apart-pull basin of Shaanxi Province in relation to gold mineralization

作　　者：方维萱[1,2] 黄转盈[1] 

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

出　　处：《中国地质》2012年第5期1211-1228,共18页Geology in China

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

摘　　要：陆-陆斜向碰撞过程中形成的拉分盆地及构造变形史、变形样式及动力学、流体大规模运移与构造岩相学记录等是值得重视的大陆动力学问题,也有助于对西秦岭卡林型-类卡林型金矿和多金属矿成矿规律的深入研究。西秦岭陕西凤县—太白县晚古生代拉分盆地是热水沉积-改造型多金属矿床和金矿集中区。本文采用构造-岩相学研究方法,对该拉分盆地的构造-热流体变形历史、变形样式及动力学、盆地流体驱动力等进行了研究,认为该拉分盆地构造变形史复杂,构造变形序列为:(1)石炭纪—中三叠世构造反转与热流体叠加改造期(DS1)。(2)印支期陆-陆全面斜向碰撞挤压体制下拉分盆地发生挤压收缩变形、断裂-褶皱作用、岩浆侵位形成热叠加改造和脆韧性剪切变形(DS2)。(3)燕山期陆内造山期构造断陷、岩浆侵位形成热叠加改造与脆性变形(DS3)。石炭纪—中三叠世反转构造样式为泥盆系发生分层剪切流变构造、热流体角砾岩化叠加构造岩相和南部温江寺—留凤关拉分断陷盆地。印支期—燕山期,该盆地内部构造变形样式有复式褶皱与压扭性断裂构造、脆韧性剪切带、逆冲推覆构造、反冲构造与冲起构造。在该盆地南北缘形成了对冲式逆冲推覆构造。盆地流体运移受构造变形驱动,在该盆地东部,印支期西坝复式中-酸性岩浆侵入提供了区域性热流体叠加改造的稳定热源场。研究认为"M-W"型复式背斜和断裂带控制了多金属矿床后期改造富集和矿体定位。反冲构造与冲起构造控制了金矿和多金属成矿分带。"W-M"型复式向斜和脆韧性断裂带控制了卡林型-类卡林型金矿的形成,其中,倒转向斜和脆韧性剪切带对于八卦庙类卡林型金矿多期多阶段富集成矿具有显著控制作用,温江寺卡林型金矿受复式向斜和脆性断裂带控制。The studied apart-pull basin was formed during the oblique-direction subduction and collision of the Huabei and Yangtze Plates.The tectonic deformation history,styles,dynamics,records of tectonic lithofacies and large-scale migration of fluids in the apart-pull basin constitute some of the most important problems in the continental dynamics,and the study of these problems are helpful to the detailed investigation of the mineralization regularity and the controlling factors of polymetallic deposits,Carlin-type gold deposits and similar ore deposits in the West Qinling orogeny.The Late Paleozoic apart-pull basin in Shaanxi is the high-density area which hosts not only Sedex-type polymetallic deposits but also Carlin-type gold deposits and similar deposits.Tectonic deformation history,styles and dynamics of the Fengxian-Taibai apart-pull basin and the driving factors of fluid migration in the basin were studied by the authors based on the tectonic lithofacies.Sequences of tectonic deformation for the apart-pull basin have been classified into three main deformation stages although it has more complicated tectonic deformation history.The first stage was tectonic inversion and superimposition of hydrothermal fluid in Carboniferous-Middle Triassic period（DS1）,the second stage was compressive and shrinking deformation of the basin,faulting and folding,hydrothermal superimposition by magmatic intrusion,and brittle-ductile shear deformation（DS2） during the Indo-China main orogeny resulting from the full-scale continent-continent collusion,and the third stage was tectonic taphrogeny and brittle compressed deformation of the basin during the Yanshanian intracontinent orogeny（DS3）. Styles of tectonic inversion and superimposition of hydrothermal fluids during the Carboniferous-Middle Triassic period（DS1） included layering shear rheology tectonics,zone of hydrothermal brecciation,and hydrothermal fluid superimposed lithofacies in the Devonian fill-up of the basin.At the same time,Wenjiangsi-Liufengguan apart-p

关 键 词：拉分盆地 卡林型-类卡林型金矿 盆地变形序列 盆地变形样式 构造变形动力学 

分 类 号：P618.51[天文地球—矿床学]