【作者】 徐明钻；

【导师】 朱立新； 马生明；

【作者基本信息】 中国地质科学院 ， 地球探测与信息技术， 2011， 博士

【摘要】 北山地区地处哈萨克斯坦板块、塔里木板块、华北板块交汇部位,在地质演化史中经历了复杂的造山运动和多期次的岩浆活动,为该区创造了有利的成矿地质条件。迄今为止已经发现中型铜矿床2处,小型铜矿床1处,铜矿(化)点58处,显示出良好的铜矿找矿前景。但是区内特大型、大型铜矿地质找矿工作尚未取得突破,表明现有铜矿地质找矿方法技术仍需改进和完善,而化探方法技术即在此列。本文选择以北山地区具有典型代表意义的白山堂斑岩型铜矿、辉铜山矽卡岩型铜矿为研究对象,以成矿地球化学环境理论为指导,兼顾铜矿化过程中发生富集的元素和发生贫化的元素,系统开展元素地球化学分布规律的研究,意在总结出能有效反映铜矿成矿地球化学环境的勘查地球化学指标,通过开展元素表生活动性规律研究,总结元素表生环境中活动特性与原生环境中活动特性之间的继承关系；并以上述研究结果为基础,开展北山地区铜多金属矿的成矿远景区预测和找矿靶区优选方法技术研究工作,为北山地区铜多金属矿地质找矿工作指明方向。白山堂铜矿储量最大的铜矿体赋存在华力西中期流纹斑岩体与蓟县系平头山群地层接触带上,其成矿作用与流纹斑岩体有关。在矿区内开展矿体及围岩中元素地球化学分布规律研究,从中总结出两类勘查地球化学指标共33项,包括20项富集指标和13项贫化指标。元素表生活动性规律研究结果表明：(1)与岩石丰度相比,不同母岩中元素富集贫化特征差异明显,且土壤中元素含量明显受母岩控制；(2)土壤粗粒级在物质组成、化学成分上与母岩更为接近；(3)土壤-4～+40目粒级中发生富集元素的表生富集作用最为强烈,而发生贫化的元素的表生富集作用则相对偏弱；(4)随着样点到矿体距离的增加,土壤-4～+40目粒级中Cu、Mo等元素含量明显降低,而Na2O元素含量则较明显升高；(5)以-4～+40目粒级为有效采样介质,很好地圈出了元素的正异常及负异常,指导该区找矿靶区优选工作。辉铜山矽卡岩型铜矿铜矿体赋存在奥陶系花牛山群大理岩与燕山早期钾长花岗岩体的接触带上,其成矿作用明显受钾长花岗岩控制。依据矿体及围岩中元素地球化学分布规律研究结果,总结出两类共24项勘查地球化学指标,包括17项富集指标和7项贫化指标。元素表生活动性规律研究显示：(1)与岩石丰度相比,不同母岩中元素富集贫化特征差异明显,且土壤中元素含量明显受母岩控制；(2)土壤粗粒级的物质组成及化学成分更接近于母岩；(3)不同类型土壤中元素的表生富集作用也不尽相同,在-40目粒级中,大部分元素的表生富集作用达到最强,并且元素的表生富集作用与粘土矿物含量呈正相关关系,与主要造岩矿物含量呈负相关关系；(4)随着样点到矿体距离的增加,土壤-4～+40目粒级中Cu、Mo等发生富集的元素含量明显降低,而Ba、Sr等发生贫化的元素含量则略有升高：(5)以-4～+40目粒级为有效采样介质开展试验工作,结合矿化过程中发生富集元素形成的正异常和发生贫化元素形成的负异常,综合进行靶区优选的方法,具有更加直接和准确的指示作用。在北山地区成矿远景区预测方法技术研究中,依据元素地球化学性质及不同元素与Cu之间对数含量一元线性回归分析结果,总结出了两类四组共13项预测指标,并根据数据百分位方法确定异常下限和异常上限,以此为基础,提出了综合预测指标；同时,对预测过程中涉及的基本预测单元、异常图件编制、预测指标异常的分类等作了明确的规定和详细的说明。以上述研究结果为基础,圈定北山地区A、B、C类综合预测指标异常共85处,其中A类36处,B类25处,C类24处；划分出北山地区铜多金属矿成矿远景区共15处,并依据各成矿远景区成矿地质条件分析结果,预测各成矿远景区的成矿前景。选择北山地区两类共五处综合预测指标异常开展找矿靶区优选示范工作,取得成果如下：(1)指出白山堂铜矿试验区三矿带和四矿带重叠部位北部的一处有利Cu成矿地段；(2)确定2010-1号试验区主成矿元素应该为As、Sb,并指出一处有利成矿地段；(3)指明2009-1号试验区成矿前景不明朗;(4)2009-2号试验区研究结果显示,该区Ⅲ号Cu异常具有较好的成矿前景；(5)指出2010-2号试验区中一处有Cu矿成矿前景较好的地段,并依据地质背景分析,认为该地段如果成矿,形成热液型矿床的可能性不大。更多还原

【Abstract】 Beishan region locates in the intersection part of Kazakhstan plate, Tarim plate and North China plate. Complex organic movement and multiple-period magmatic movements in long geological evolution history, created favorable metallogenic geological conditions in Beishan region. Two medium-scale copper deposits, one small-scale copper deposit, fiftyeight ore or mineralized occurrences have been found out in this region heretofore, which shows good prospects for copper deposits exploration. However, geological prospecting for super larger-scale or large-scale copper deposits has not been made breakthroughs, which give the facts that the geological prospecting methods and technology of copper ore, including geochemistry exploration methods and techniques, needs to be mended and improved.Two typical deposits, including Baishantang porphyry copper mine and Huitongshan copper mine, were chosen as study targets in this paper. Based the metallogenic geochemical environment theory, and taking account of enriched and depleted elements in copper mineralization process, elements geochemical distribution was systematically studied for summarizing geochemistry indexes which can effectively reflect copper ore-formation; supergene activity regular of elements was researched in order to illustrate the inheritances of elements’activity from primitive to supergene environment. Based on these results, the methods and techniques of forecasting metallogenic prospective areas about copper-polymetallic deposits and prospecting targets optimization were studied for demonstrating the direction of geological exploration.The largest reserves ore body of Baishantang mining district, whose metallogeny was controlled by Middle Hercynian rhyolite-porphyry, hosted in the contact belt between rhyolite-porphyry body and stratum of Jixian series Pitoushan group. Two groups in total of 33 exploration geochemistry indicators, consisting of 20 enriched indicators and 13 depleted indicators, were summed up by the study results of elements distribution in ore-body and hosted rocks. The study results of elements supergene activity demonstrate:1. the characteristic of elements enrichment and depletion among different parent rocks show obvious differences, and the contents of elements in soils was controlled by parent rock; 2. comparing with fine fraction, the material and chemical composition of coarse fraction of soil show more similar to parent rocks; 3. in-4～+40 fraction of soils, enriched elements show most intensive supergene enrichment, but more weaker supergene depletion of depleted elements; 4. as the distance of samples to ore-body increasing, the contents of Cu, Mo significantly decreased in-4～+40 fraction of soils, inversely, the content of Na2O increased; 5. positive and negative anomalies were delineated based on taking-4～+40 fraction in effective sampling medium, which directed the prospecting targets optimization.Huitongshan skarn copper ore-body, whose metallogeny was obviously influenced by Early Yanshan feldspar granite body, hosted in the contact belt between stratums of Ordovician Huaniushan group and feldspar granite body. Two groups in total of 24 exploration geochemistry indicators, consisting of 17 enriched indicators and 7 depleted indicators, were summed up by the study results of elements geochemical distribution in ore-body and hosted rocks. The study results of elements supergene activity reveal:1. the characteristic of elements enrichment and depletion among different parent rocks show obvious differences, and the contents of elements in soils was controlled by parent rock; 2. comparing with fine fraction, the material and chemical composition of coarse fraction of soil show more similar to parent rocks; 3. different soils show different supergene enrichments, in-40 fraction of soils, the supergene enrichment of almost elements achieve most intensively; positive correlation between elements enrichment and the contents of clay mineral and negative relationship between elements enrichments and the contents of rock-forming mineral were discovered; 4. as the distance of samples to ore-body increasing, the contents of Cu, Mo significantly decreased in-4～+40 fraction of soils, inversely, the content of Ba、Sr slightly increased; 5. based on taking-4～+40 fraction in effective sampling medium the experiment of prospecting target optimization was carried out, the results show that integrate the positive anomalies formed by enriched elements and negative anomalies formed by depleted elements in mineralization process to optimize prospecting target, can show more substantive and exact indication to discover ore-body.In the study of methods and techniques of metallogenic prospecting areas prediction,2 kinds and 4 groups in total of 13 forecasting indicators were found out on the basis of elements geochemical characteristic and the logarithmic contents linear regression analysis results between Cu and other elements; the upper limit and lower limit of anomalies were made sure by percentile method; comprehensive predictive indicator was put forward. Furthermore, basic prediction unit, anomaly maps production and classification of predictive indicators anomalies were definitely specified and detailed illuminated. Base on the aforesaid researching results,3 kinds in total of 85 comprehensive predictive indicator anomalies, including 36 A anomalies,25 B anomalies and 24 C anomalies, were delineated; 15 copper-polymetallic deposits prospecting areas were made out, and metallogenic prospect of each area was forecasted on the basis of the analysis of metallogenic geological condition of each area.Prospecting target optimization was carried out in 2 kinds in total of 5 comprehensive predictive indicator anomalies based the study of anomaly structure, the achievements were showed as following:1.in Baishantang copper deposit test region, a favorable section for Cu metallogeny, which located in the northern of the overlapping position of No.3 and No.4 ore belt, was pointed out; 2. in No.2010-1 test region, As and Sb were made sure as main metallogenic elements, a favorable metallogenic section was clearly showed; 3. results showed that No.2009-2 test region do not has distinct metallogenic prospects; 4. in No.2010-2 test region, a favorable section for Cu metallogeny was pointed out, hydrothermal type deposits unlikely formed in this section based on geological setting analysis.更多还原