【作者】 高亚林；

【导师】 汤中立；

【作者基本信息】 兰州大学 ， 地质工程， 2009， 博士

【摘要】 随着我国经济的高速发展,对资源的需求越来越大。目前我国铜、镍、铂族金属资源保障形势日趋严峻,如何提高该类矿产资源的研究程度,创新铜镍硫化物矿床的成矿理论,完善成矿演化模式认识,指导已知矿床深边部找矿工作,也就显得越来越重要。赋存于超镁铁质岩的金川矿床,是目前世界第三大在采硫化铜镍矿床;金川矿区也成为我国最大的Ni、Cu、PGE金属资源供应基地,其Ni产量占全国88%,PGE占90%,Cu占13%以上。经过近五十年的开采,金川部分富矿体已逐渐被开采殆尽,资源危机已开始显露端倪,如何在金川矿区深边部找到新的接替资源问题已成为当务之急。本文以金川超基性岩浆侵位期次、岩浆演化模式为研究主线索,以金川铜镍硫化物矿床的成矿时代、成矿作用机制、就位机制、岩浆演化—成矿模型、Ⅰ-⑥富铜隐伏矿体地质特征及成因研究为重点内容,以预测矿区深边部找矿靶区服务矿山生产为目的。这无论对指导金川矿区深部和边部找矿,扩大资源储量,延长矿山服务年限,还是对完善成矿理论认识应用于其他类似矿区找矿,都具有重要的现实意义。论文的主要研究内容及成果如下:(1)在收集和综合分析大量地质资料的基础上,利用Surpac软件,建立了矿床三维可视化模型,明晰、直观地表现了矿床含矿超基性岩体、主矿体、矿区主要构造之间的三维空间关系。通过对超基性岩体空间关系、形态特征的分析,认为:金川超基性岩体分为东、西两段和东、中、西三个成矿富集块段。东段岩体以出现大量的含斜长石岩相为主要特征,西段岩体以不出现或只局部出现斜长二辉橄榄岩异离体与东段岩体相区别。从东、西成矿富集块段往中富集块段,岩体和赋存矿岩相的基性程度增高,形成矿体的成矿元素富集程度增高。(2)在对Ⅰ-⑥隐伏矿体同位素测年数据的基础上,系统收集前期同位素测年资料,综合分析,试用发展的、联系的态度来解释,初步认为:金川矿床主矿体的形成时间为8～10亿年;Ⅰ-⑥等富铜隐伏矿体一般侵位于8亿年左右:镍特富矿体侵位时间为8亿年前。这对矿床所在区域成矿环境演化以及指导深边部找矿具有重要指导意义。(3)从矿体特征、矿石特征和矿石特殊地球化学特性等方面,与Ⅱ-①主矿体进行对比,总结了Ⅰ-⑥隐伏矿体的矿化规律,并指出其既有岩浆熔离作用的特点,又有后期改造作用的特征,其形成经历了三个阶段:富含Cu、PGE岩浆深部熔离-脉动贯入、构造活化富集和后期热液叠加。探讨了来源于地幔深部的高镁玄武岩浆,在深部岩浆房和阶段岩浆房熔离分异时,富(镍)矿岩浆和矿浆之间存在富(铜)矿岩浆。此外,Pb、S同位素表明,该矿体岩浆主要来源于地幔,但曾被少量地壳物质混入。(4)岩(矿)体的定位受含矿岩浆、矿液活动中心的控制,而最关键的控制因素还是与岩浆、矿液活动中心相连接的岩浆通道的出口。通过对比分析各矿区主矿体的主要地质特征和研究Cu、Ni、Pt、Pd、Au、Ag等元素的富集规律,指出:Ⅱ矿区Ⅱ-①矿体6～8行深部可能为含矿岩浆、矿液活动的富集中心:Ⅰ矿区与Ⅱ矿区结合地段、Ⅱ矿区1号矿体与2号矿体结合地段、Ⅲ矿区南侧等三片为重点找矿预测区。(5)在评价物、化探、遥感技术和新技术方法等勘查技术方法的基础上,根据金川铜镍矿山的实际情况,建立了分别适用于金川铜镍矿山深部和边部寻找矿产资源的综合勘查技术方法组合。更多还原

【Abstract】 With the rapid development of Chinese economy,the demand for resources would increase intensively.At present,the situation for metal resources guarantee of nickel, copper and PGE in China is increasingly serious.How to improve the research degree of these mineral resources,innovate the metallogenic theory of Cu-Ni sulfide deposits, perfect the ore-forming evolution model,and guide the prospecting in the depth and border of known deposits,become more and more important.The Jinchuan deposit,hosted by olivine-rich ultramafic rocks,is the world’s third largest magmatic Cu-Ni sulfide deposit being currently exploited.Jinchuan is also the largest supply base of Ni-Cu-PGE in China,whose Ni output is 88%of that in the whole China,PGE is 90%,and Cu is more than 13%.It has been prospected and exploited for more than fifty years since it was discovered in 1952.Part of high-grade orebodies has almost been depleted.The resource crisis begins to appear.Therefore how to discover alternative resources in the depth and border of Jinchuan Deposit becomes very urgent.The main clues of the study are the emplacing stage of Jinchuan ultrabasic magma and the evolutional model of magma.Its main research contents are the metallogenic epoch,the ore-forming mechanism,the emplacement mechanism,the magma evolutional-metallogenic model of Jinchuan Cu-Ni sulfide Deposit,the geological characteristics and genesis ofⅠ-⑥Concealed Cu-rich orebody.Its purpose are to predict the prospecting target area in the depth and border of Jinchuan Deposit and serve the Jinchuan mine.It has very practical significance for guiding the prospecting in the Jinchuan Deposit, increasing its mineral resources,prolonging its Mine Service Life and serving other similar deposits for prospecting by using this perfect metallogenic theory.The main research contents and results are as follows:(1) Based on much geological data and the Surpac software,the three-dimensional visual model of Jinchuan Deposit had been built.It would distinctly and visually demonstrate the three-dimensional relationship among the Jinchuan ore-bearing ultrabasic rockbodies,the Jinchuan main orebodies and the Jinchuan main structure.Through analysis of spatial relationship and morphological characteristics of Jinchuan ultrabasic rockbody,it is realized that the Jinchuan ultrabasic rockbody is divided into two parts (East Part and West Part) and three concentrative segments(East,Middle and West).The main lithofacies feature of East Part rockbody contains large plagioclase,while there locally exists little(or doesn’t exist) plagioclase-bearing lherzolite in the West Part rockbody.The basicity of rockbody and ore-beating lithofacies becomes gradually higher, and the enrichment degree of main ore-forming elements increases accordingly,from the East concentrative segment and the West concentrative segment to the Middle one.(2) On the basis of isotope dating data ofⅠ-⑥Concealed Cu-rich orebody,the previous isotope dating data were systematically collected,synthetically analyzed,then explained with the attitude of development and inter-relation.The preliminary conclusions could be drawn out,which are that the forming age of Jinchuan main orebodies was 800-1000Ma,theⅠ-⑥Concealed orebody formed at 800-1000 Ma,and the emplacement age of massive Ni-rich orebodies was earlier than 800 Ma.The view is of great significant to the study on the evolution of regional metallogenic environment and guidance the prospecting in the depth and border of Jinchuan Deposit.(3) By comparing the characteristics of orebody,ore and special geochemistry between theⅠ-⑥Concealed orebody and neighboringⅡ-①main orebody,theⅠ-⑥’s mineralization characteristic was summed up.It is concluded that theⅠ-⑥Concealed orebody has the feature of both magmatic liquation and late reformation.Meanwhile,it is implied that there existed a Cu-rich magma between ore-bearing Ni-rich magma and ore pulp during differentiation by liquation of High MgO Basalts magma derived from mantle in the deep staging chambers.The magma ofⅠ-⑥Concealed orebody experienced three stages:first,the deep liquation and pulsatory injection of the Cu- and PGE-rich magma; second,the concentration of tectonic activation;third,the later magma hydrothermal superposition.In addition,Pb and S isotope data indicate the magma ofⅠ-⑥concealed orebody predominantly originates from mantle,but is contamined by a small crustal component.(4) The location of rockbody and orebody is controlled by the activity center of ore-bearing magma and ore pulp,among which the most critical controlling factor is the magma conduits connecting with the activity center of ore-bearing magma and ore pulp. Through contrastive analysis on the geological characteristics of main orebodies of each Mining Area and study on the enrichment law of such elements as Cu,Ni,Pt,Pd,Au and Ag etc.,it is pointed out that there might be a activity center in Exploration Line 6-8 of JinchuanⅡ-①main orebody;the junction between Mining Area-Ⅰand Mining Area-Ⅱ, the junction betweenⅡ-①main orebody andⅡ-②main orebody,and the south of Mining Area-Ⅲare the critical prospecting targets.(5) Based on evaluation of geophysical exploration,geochemical exploration, remote sensing technology and other geo-exploration technology etc.,the rational and synthetical combination of prospecting techniques for exploring in the depth and border of Jinchuan Deposit are respectively established according to the actual conditions of Jinchuan Deposit.更多还原