【作者】 李进文；

【导师】 裴荣富； 张德全； 张荣华；

【作者基本信息】 中国地质科学院 ， 矿产普查与勘探， 2004， 博士

【摘要】 铜陵矿集区位于安徽省铜陵市，是长江中下游成矿带中段的大型铜金矿集区。研究表明，区内铜（金、硫、铁）矿床与中酸性侵入岩具有密切时空和成因联系。这些侵入岩受基底和盖层构造的控制，主要沿铜陵-沙滩脚构造-岩浆带分布，形成时代集中于148.20±2.13～134.35±3.03Ma，总体上是从花岗闪长岩→石英二长闪长岩→辉石二长闪长岩依次侵位的。侵入岩由高钾钙碱性系列和碱性系列组成，两者间不存在演化关系，前者主要为下地壳底部深变质岩发生部分熔融形成的岩浆在有少量幔源玄武质岩浆注入的情况下先于后者形成；后者是幔源碱性玄武质岩浆与有限的地壳物质发生同化混染进而通过结晶分异作用形成的。下地壳或岩石圈地幔拆沉继而环流热幔上涌是侵入岩形成的直接起因，中酸性侵入岩浆的强烈活动也标志着本区构造环境由挤压向伸展的调整，而大规模的铜（金、硫、铁）成矿作用即发生于伸展构造环境中。侵入岩的“体中体”构造发育；岩浆多次侵入活动具有共岩浆补余分异效应，且对大规模的金属成矿作用可能起到了重要作用；岩体冷速率一般与其相关成矿作用的强度成反相关。区内矿床可划分为热液脉型、矽卡岩型和层控矽卡岩型3个主要成因类型，不同类型的矿床受不同的构造控制。根据控矿特征，矿田构造可分为浅带“行、列、汇”构造样式、中带岩浆侵入接触构造体系和深带“隆中凹”构造，三者的深度分别为0～1km左右、1～3.0km左右和＞3.0km，在空间上构成了矿田构造的垂直分带。三个层次的控矿构造带分别控制了热液脉型矿床（体）、矽卡岩型矿床和层控矽卡岩型矿床。浅、中、深控矿构造带在不同的矿田常具有不同的组合形式，可以单独出现，也可以是两两组合，当三者完全产出时则构成了完整的矿田构造垂直分带。矿田构造垂直分带的发育程度是控制“多位一体”成矿和矿床成矿组合的主要原因。矿田构造的形成、演化经历了海西期“隆中凹”构造的形成和发育、印支期褶皱和层间滑脱构造的形成、燕山期层间滑脱构造的发育和岩浆侵入接触构造体系及“行、列、汇”构造样式的成生与演化等阶段。各类矿床矿石中石英、方解石和石榴石矿物流体包裹体的观测表明，流体包裹体可以分为富气相包裹体、富液相包裹体和含子晶多相包裹体三类，其均一温度变化范围较大，为128～＞570℃；盐度变化于1.07～60.72wt％NaClequiv，其中含石盐子晶包裹体的盐度为30.27～60.72wt％NaClequiv。矽卡岩型矿化初始阶段的成矿流体呈超临界态，并在成矿主阶段发生过流体沸腾或不混溶作用。减压降温是引起成矿流体发生沸腾的原因，也是导致流体中矿质淀积的主要因素。流体包裹体的均一温度和盐度变化特征表明，热液脉型矿化稍晚于矽卡岩型矿化。成矿流体以H₂O、CO₂、N₂、Na⁺、K⁺、Ca²⁺，Mg²⁺、SO₄^2-、Cl^-为主要成分，含有少量到极少量的CH₄、He、Ar、O₂、C₂H₆、H₂S等成分，少量样品含F^-；流体中CO₂、O₂、Ca²⁺、K⁺、SO₄^2-、Cl^-和F^-等成分的含量可能对成矿规模具有重要的控制作用。从早阶段到晚阶段，成矿流体经历了由还原性增强再降低的动态演化过程，而还原性增强有利于金属硫化物的沉淀。成矿流体主要来自岩浆水，而且流体从岩浆分出时已含有一定量的铜等成矿元素，并在岩浆-流体的相互作用过程中，其中的成矿元素逐渐富集。水-岩反应动力学实验研究揭示，流速相对较低的流体有利于Cu、Mo和Zn等成矿元素从岩石中溶出，水-岩反应速率与流体流速基本成反相关，与流体在体系内的停顿时间成正相关，但反应速率是呈非线性变化的。成矿流体中的Cu可能主要是在超临界态流体中迁移，而在低于临界态条件下从流体中析出；在低于临界态的350℃温度条件下，Zn元素仍保持从岩石中呈大量溶出，可能因此导致了Cu、Zn等成矿元素在空间上常构成分带特征。同位素测年表明，区内金属成矿经历了海西期和燕山期两个时代，成矿作用时限分别为313.2±32.7Ma～290±10Ma（晚石炭世）和140.3±1.7Ma～134.2±3.9Ma（晚侏罗世～早白垩世）。但燕山期为主成矿期，中酸性侵入岩是铜（金、硫、铁）矿床成矿物质的主要来源，海西期原始沉积矿胚层是层控矽卡岩型矿床的重要成矿场地准备，仅提供了很少的矿质。与侵入岩有关的热液成矿早阶段的流体为岩浆热液，主阶段和晚阶段有大气降水或地下水的参与，而一定深度岩浆房的流体和矿质补充对大规模的铜、金成矿作用是非常重要的。应用演化成矿概念，以区域地质构造演化为背景，分析总结了铜陵矿集区的成矿地质演化历史。研究了矿集区的内部结构及其与地球化学块体的关系，根据成矿时限与矿床储量相对丰度相关关系评估了燕山期铜矿成矿强度，并在此基础上分析了找矿方向。更多还原

【Abstract】 The Tongling mineral assemblage area, situated in Anhui province, is a large one in theMiddle-lower Yangtze River metallogenic belt. The recent researches showed that there are closetemporal, special and genetic relations between the copper（gold, sulfur and iron） deposits and theintermediate-acid intrusive rocks. The rocks intruded from 148.20±2.13 to 134.35±3.03Ma and ingranodiorite→quartz monzodiorite→pyroxene monzodiorite order, and controlled by the structuresof basement and covers mainly distribute along the Tongling-Shatanjiao tectonomagmatic belt.They consist of alkaline series and sub-alkaline series, but both the series have no evolutionalrelation. The original magma of the high-K talc-alkaline series was mainly partial melting materialof old metamorphic basement rocks, and mixed by a little basaltic magma of mantle. The primalmagma of the alkaline series was alkaline basalt which originated from the enriched mantle andunderwent assimilation, fractionation and crystallization. Delamination of lower crust orlithospheric mantle followed by thermal mantle moving up brought directly on formation of theintrusive rocks. The magma activities are the indication of tectonic setting changing fromcompression to extension, and the large-scale copper（gold, sulfur and iron） ore-forming processoccurred in the extensional tectonic setting. The intrusive rocks develop structures of "intrusivebodies in body". The multiple intrusive activities have co-magmatic complementary differentiationwhich may be beneficial to mineralization. The cooling rates of the intrusive bodies are commonlycounter-correlation to mineralization.The metallic deposits in Tongling could be classified into three main types: hydrothermalvein-type, skarn-type and stratabound skarn-type, and these deposits are controlled by differentstructures. According to the ore-controlling characteristics, the structures of orefield in the Tonglingmineral assemblage area were classified into "row-line-cluster" pattern, contact structure system ofmagma intrusion and "depression in swell". They occur respectively epizone（0-1km）,mesozone（1-3.0km） and hypozone（＞3.0km） in the space so as to form a vertical zoning of thestructures of orefield. The three zones of ore-controlling structures control respectivelyhydrothermal vein-type deposits, skarn-type deposits and stratabound skarn-type deposits. May besingle or both, or maybe all of them that form a integrate vertical zoning of the structures of orefield,the epizone, mesozone and hypozone may combine different formats. The vertical zoning of thestructures of orefield is the main cause controlling the metallogenic assemblage and multistorymineralization. The structures of orefield mainly went through three stages: formation anddevelopment of"depression in swell" in the Hercynian; formation of the folds and interlayer glidingstructures in the Indosinian; development of interlayer gliding structures, formation anddevelopment of contact structure system of magma intrusion and "row-line-cluster" pattern in theYanshanian.Three types of fluid inclusions, namely gas-rich, liquid-rich and daughter mineral-bearingpolyphase brine inclusions were distinguished in quartz, calcite and garnet. The temperature ofhomogenization of fluid inclusions ranged from 128℃to＞570℃. The salinities of three types ofinclusions varied remarkable from 1.07 to 60.72 wt％NaCI equivalent and the halite-bearinginclusions with high salinities from 30.27 to 66.75 wt％NaCl equivalent. Ore-forming fluid of the skam mineralization might behave in a supercritical state in the early stage, and occurredimmiscible separation or boiling of fluid in the major mineralization stage. The changingcharacteristics of the temperature of homogenization and salinities of the fluid inclusions showedthat the mineralization of hydrothermal vein-type appreciably lagged the skarn mineralization. Thecomponents of fluid inclusions are mainly H₂O, CO₂, N₂, Na⁺, K⁺, Ca²⁺, Mg²⁺, SO₄^2-, Cl^-, and alittle CH₄, He, Ar, O₂, C₂H₆ and H₂S. Only a few samples contain F^-. It was suggested that contentsof CO₂, O₂, Ca²⁺, K⁺, SO₄^2-, Cl^- and F^- in the ore-forming fluid might control the metallogenic size.Changing from reduction increasing to dropping, ore-forming fluid displayed a dynamicevolvement from early stage to late stage. Reduction increasing is beneficial to deposit of thesulfides. Ore-forming fluid mainly originated from magma water, and it contained someore-forming elements like copper and so on in the primitive magma-derived fluid. Ore-formingelements in the fluid were gradually increasing in the process of the interaction between magma andfluid.The experimental studies on kinetics of water-rock reaction showed that slowly flowing fluidbenefited ore-forming elements like Cu, Mo, Zn and so on dissolving from rocks, and thewater-rock reaction rate was commonly counter-correlation to flow rate of the fluid and correlationto holdup time of the fluid. The water-rock reaction rate varied in a non-linearity state. Copper inore-forming fluid might migrate in the supercritical state, and deposited under critical state. As agreat deal of zinc in rocks still released into the fluid at 350℃so that it always make up spatialzone for ore-forming elements like Cu, Zn and so on.Based on isotopic ages of the deposits, it’s considered that metallogeny in Tongling mineralassemblage area had undergone the Hercynian （from 313.2±32.7 Ma to 290±10Ma） and theYanshanian （from 140.3±1.7Ma to 134.2±3.9Ma）. The major metallogenic period belong to theYanshanian, and ore-forming material mainly derived the intermediate-acid intrusive rocks. It wasestimated that about 10 percent ore-forming material were provided for the stratabound skam-typedeposits by the Hercynian primal sedimentary source bed. The hydrothermal mineralization relatedto intrusive rocks was predominated by magma-derived fluid in the early stage and meteoric waterin the major and late ore-forming stage. It’s vary important that the ore-forming fluid derived fromdeep magma chamber complemented the large-scale copper-gold mineralization.Based on the evolvement of regional tectonics, applying the concept of evolutionarymetallogeny, the ore-forming evolutionary history of Tongling mineral assemblage area wassummarized. The relation between interior structure of Tongling mineral assemblage area andgeochemical blocks had been studied, and the metallogenic intensity of copper in the Yanshanianhad been evaluated based on the research on the relative abundance of the ore reserve and the timelimit of metallogenic processes. In the final, the prospecting direction for the copper deposits hadbeen pointed out.更多还原