长江中下游成矿带的幔根构造与深部找矿  

Mantle Rooted Structure and Deep Ore Prospecting in the Middle and Lower Reaches of the Yangtze River

作　　者：真允庆 束乾安 戴宝章[4] 汪莎[1,2] 陈国衡 花林宝[1,4,5] 丁梅花[1,2] 郝红蕾[1,2] 

机构地区：[1]江苏省有色金属华东地质勘查局,南京210093 [2]江苏省有色金属华东地质勘查局814队,江苏镇江212005 [3]中国冶金地质勘查工程总局三局,太原030002 [4]南京大学地球科学系,南京210007 [5]江苏华东有色矿业发展有限公司,南京210007

出　　处：《地质调查与研究》2009年第2期105-116,共12页Geological Survey and Research

基　　金：江苏省自然科学基金项目:长江中下游地区铁;铜;硫金矿床成矿规律与找矿预测研究(BK2008026)

摘　　要：长江中下游铁铜金多金属成矿带,正处于华北板块与扬子板块碰撞造山带的断裂构造部位。由于岩石圈大尺度不连续和地壳减薄无山根的成矿背景,促使燕山期热事件成为断裂-盆地-岩浆-成矿带的响应。区内I型花岗岩是地幔基性岩浆底侵与壳幔相互作用的结果,包体研究和透明地震反射区资料证明它们具有软流圈上涌与下地壳拆沉作用的印记,也是幔根构造的源地。正因为透岩浆流体作用,形成大量金属矿床,因而这些矿床的成矿时代具有突发性和规律性,同时成矿物质来源具有多源性和不均匀性;成矿流体具有同一性和矿床类型的多样性;成矿期次具有叠加改造性。从S、Pb、Sr、H、O、C、Si、Cu等同位素组成取得的信息,也可作为幔根构造壳幔同熔成矿的佐证。按照幔根构造成矿机理分析,预测本区仍有第二成矿空间(-500^-2 000 m),建议以"类埃达克岩(体)"为中心的地区,可作为新一轮找矿的首选区。运用综合方法(遥感、磁、电、重、地震及深穿透地球化学等),以探明深部与下古生界碳酸盐岩的接触带为主攻目标,建立四维成矿模型,确定找矿靶区,尽快进行钻探验证。The iron-copper-gold polymetallic metallogenetic belt of the middle and lower reaches of the Yangtze River is located in the fault structure of the collisional orogenic belt between North China Block and Yangtze Block. Because the lithosphere in a large-scale discontinuous and crustal thinning and no root of mountain mineralization background, the Yanshannian thermal event responsed for the fauh-basin-magma-metallogenetic belt. I-type granites of this region were the results of the mantle-derived basic magma underplating and the interaction between mantle and crust. It is confirmed by inclusion and seismic tomography （or reflection？ ） study that lithospheric mantle and lower crustal delamilation had took place and that is the source of mantle rooted structure. A pleny of metal deposits had been formed by magmatic fluids. These metal deposits are characterized by break out in mineralization time, multiple and heterogeneous in material sources, homogeneous in mineralization fluids and variety deposit types and multi-stages of mineralization and superimposition modification. The S, Pb, Sr, H, O, C, Si and Cu isotopic compositions show that mantle rooted structure had been existed and mineralization by crust-mantle syntexis. Base on the mantle rooted mineralization theory the author speculate that there existed secondary mineralization space （-500--2000 m） in the middle and lower reaches of the Yangtze River and suggest that the analogous adakite-like rocks and its peripheral areas are the first choice place in the new round prospecting. By employ comprehensive methods such as remote sensing, magnetic prospecting, electrical prospecting, gravity exploration, seismic exploration and geochemical method with earth deep-penetrating, we should focus the contact belt between lower Palezoic of carbonic rocks and underlying crust as the main target for prospecting in the next phase in these area. As a result, we could establish four-dimensional model of prospecting in order to determine the target prospecting regio

关 键 词：岩石圈大尺度不连续 地壳减薄 底侵 拆沉作用 幔根构造 铁 铜 金 多金属成矿带 长江中下游 

分 类 号：P612[天文地球—矿床学]