Stream sediment geochemical exploration for gold in Central Eastern Desert,Egypt: Application of the concentration-number fractal model,factor analysis,and geochemical mineralization probability index

Geochemical exploration by stream sediment sampling using bulk leach extractable gold (BLEG) technique and applying concentration-number (C-N) fractal model, factor analysis (FA), and geochemical mineralization probability index (GMPI) resulted in the recognition of new Au occurrences around the Sukari gold mine in the central Eastern Desert of Egypt. The geochemical data of 128 stream sediment samples collected from the study area was used for delineating the geochemical anomalies and characterizing the dispersion trains of ore and associated elements (Au, Ag, As, Sb, Cu, Pb, Zn, Mo). Statistical analysis of the geochemical data applying the C-N fractal modeling enabled us to identify significant anomaly and background populations of the investigated elements and to construct reliable geochemical anomaly maps. Factor analysis using centered log-ratios (CLR), to address the problem of closed compositional data, revealed significant element associations for mineralization (Au, As, Mo, Zn, Ba), country rock compositions (Rb, Li, Be, Sn, Bi for granite, and Co, Cr, Ni for mafic rocks), and element mobility (e.g. Sb, Zr, and Ag). Weak and moderate Au anomalies that cannot be detected by factor score maps can be delineated clearly by using the C-N fractal method and GMPI distribution map. Our study revealed that Ag, As, and Sb are the main pathfinder elements for gold mineralization in arid to semiarid regions exemplified by the Sukari gold district. Silver can be used as a “direct” pathfinder, whereas As and Sb are “indirect” pathfinders for Au in such regions. The spatial distribution of Au and Ag anomalies indicate that gold mineralization in the Sukari district is structurally controlled. However, the spatial distribution of Cu, Pb, Zn, and Mo is controlled by mineralogical and lithological factors and is not related to any significant base metal deposits.     

青海拉脊山东段水系沉积物地球化学异常特征

青海拉脊山东段水系沉积物地球化学测量,发现金源、喇嘛庙、七里寺峡Au、As、Ag、Bi、Sb、Hg等元素的水系沉积物组合异常.Au、Ag、As相对高浓度带发育形态、分布范围、异常浓集中心吻合,与区内已知尼旦沟金矿床地球化学异常特征可以类比,发现有金、铜矿体和金矿化,显示铜金成矿的有望远景地段.     

河南省嵩县萑香洼金矿矿床地球化学特征

莅香洼金矿发育有与金矿关系密切的地球化学异常,Au及相关元素的平均含量从安山岩→蚀变安山岩→蚀变岩→矿化蚀变岩呈几何级数递增。沿F985构造蚀变带走向,Pb、Ag与Au的组合异常通常与金的矿体晕分布一致,而As、Sb组合则更多反映了矿体前缘晕的组合特点,沿倾向,Au及相关元素自浅而深具有分段富集特征,并在1023m标高和976m标高构成二个浓集中心。其理想的元素轴向分带序列为：前缘晕As、Sb—Ba,矿体晕Au、Ag、Pb、Zn、Cu、Mo,矿尾晕（Cu、Mo）-（Co、Ni、Bi）。文章在前人研究的基础上,系统总结了莅香洼金矿床的地球化学特征,总结了构造蚀变岩型金矿床的地球化学找矿标志,建立了萑香洼金矿床的地球化学找矿模型。     

河北省怀安县朱家洼矿区地球化学特征与找矿方向

河北怀安朱家洼矿区位于华北板块北缘中段太古宙、元古宙、中生代金银铅锌铁硫铁矿成矿带,为火山热液型金多金属矿。为查明该区成矿规律,明确找矿方向,在区内开展了水系沉积物测量、土壤地球化学测量等工作。通过对元素分布、元素相关性、元素异常等特征研究表明,Au、Mo为本区主成矿元素;各元素异常平面分布具有分带性,高温元素W、Sn、Bi异常位于骆驼山火山机构中心,中低温元素Pb、Zn、As、Ag等异常分布于火山机构边部及周边围岩中,成矿元素Au、Mo异常主要位于火山机构西侧围岩中。异常查证发现金钼矿化体2条,金钼矿化受火山机构和北西向构造带控制。依据成矿地质条件、地球化学异常及查证成果认为,朱家洼矿区Au、Mo成矿潜力大,火山机构西侧围岩区是该区重点找矿地段。     

玲珑金矿大开头矿区47号脉微量元素特征

选择胶东玲珑金矿典型矿体47号脉为研究对象,应用基岩地球化学方法,测试微量元素含量,研究微量元素与金的相关关系、计算微量元素的浓集系数并确定其轴向分带,探讨微量元素对深部金成矿的指示意义,期待能对玲珑金矿深部找矿提供一些参考.初步认识如下:矿区金矿体的最佳指示元素依次为Au、Ag、Bi、As、Cu、Co、Mo、Sb;金矿体的轴向分带序列从上到下依次为As、Pb、Ag、Cu、Hg、Sb、Mo、Ni、Th、V、U、Mn、Zn、Bi、Co、Au;矿体中Au、Bi、Ag、As富集系数大,Cu、Co富集系数中等,而Zn在矿体中相对亏损.研究结果表明,在深部47号矿体仍有较好的成矿前景.     

内蒙古巴彦宝力道金矿区物化探综合找矿方法及其应用

巴彦宝力道金矿区位于内蒙古苏尼特左旗,区内发育与金矿化有关的破碎蚀变带和糜棱岩化带。通过研究地质及物化探工作成果,建立本区地球物理、地球化学成矿模式,采用相关分析和"格氏法"等方法,确定了矿床元素轴向分带序列为:As Sb Hg Bi Li Sr Ba Ag Pb Au Cu Zn Sn V Co Cr Ni Ti Mo W,前缘晕元素为As、Sb、Hg、Bi,主成矿元素为Au、Cu、Zn,尾晕元素为Ti、Mo、W。据轴向分带特征,确定金矿体剥蚀程度的判别指标为w(As)×w(Sb)×w(Bi)/w(Ti)×w(Mo)×w(W)。建立了找矿标志,为下一步地质找矿提供了依据。     

青海北祁连冷龙岭地区水系沉积物元素地球化学特征及异常圈定

青海冷龙岭地区位于北祁连成矿段的东段,是形成与海相火山岩有关的块状硫化物矿床及岩浆热液型矿床的有利地区,具有良好的找矿潜力。在1∶5万水系沉积物测量成果的基础上,对青海冷龙岭地区Au、Cu、Pb、Zn等17种元素的地球化学特征进行了初步分析,发现本区Ag、Pb、Zn、W、Sn、Bi、Mo、Ba、Cd等元素丰度明显高于青海省及祁连地区水系沉积物的平均丰度值;元素分布特征显示下奥陶统阴沟群除Hg、La、Ce相对贫化外,各元素都呈现不同程度的浓集,加里东期侵入岩中Ag、Cu、Pb、Zn、W、Au、Sn、Bi等元素富集程度较高,海西期正长岩内Ba、La、Ce等元素富集程度较为显著;R型聚类分析和因子分析显示区内的主要成矿元素组合为Cu Pb Ag Mo Ba La Ce,Au具有独立成矿的潜力。结合元素地球化学参数及富集离散特征,认为本区Au、Ag、Cu、Pb、Zn、Mo、La、Ce等元素具有一定的找矿潜力。本次工作共圈定8个综合异常。根据研究区成矿地质背景、异常特征及查证成果,与该区域内浪力克铜矿床和青分岭金矿床的地质地球化学特征对比研究后,优选出干沙河和三道路圈—倒阳河2个成矿远景区。     

五台山—恒山绿岩带Au-Ag-Cu成矿作用地球化学特征

五台山—恒山绿岩带Ａｕ、Ａｇ、Ｃｕ矿床可分为二大类型：（１）再生型金银铜矿，产在包括岩浆岩在内的各类岩石断裂构造中，与岩浆期后热液有关；（２）变生型金银铜矿，产于各类变质岩中，具有层控特征（即绿岩型金矿）。在地球化学特征上，再生型矿床与变生型矿床相比，矿体及围岩中Ｍｏ、Ａｇ、Ｐｂ、Ｚｎ、Ｃｄ等成矿及伴生元素明显富集；Ｋ２Ｏ、Ｒｂ、Ｓｒ、Ｂａ、Ｔｈ、Ｕ也明显富集，是后期岩浆热液作用的结果；Ｈｇ、Ｆ的明显富集则与后期构造活动有关；Ｚｎ／Ｃｄ比值较低，说明受到后期岩浆侵入影响；Ｔｈ／Ｕ比值低，可能指示富钙的酸性岩环境。再生型Ａｕ矿化的元素组合为Ｃｄ、Ａｓ、Ｎｉ、Ａｇ、Ｓｂ、Ａｕ、Ｈｇ（Ｂｉ），再生型Ａｇ矿化的元素组合为Ａｓ、Ｓｂ、Ａｇ、Ｃｄ、Ｃｕ、Ｎｉ（Ｍｏ、Ｐｂ、Ｚｎ、Ｂｉ），变生型Ａｕ矿化的元素组合较简单，只为Ａｕ、Ｈｇ、Ａｓ或Ａｕ、Ｃｕ。上述地球化学特征不仅可以有效地区分矿化类型，而且可以作为地球化学找矿和评价的指标     

黑龙江金厂金矿地质地球化学特征及矿床成因

金厂金矿金矿化分为构造蚀变岩裂隙充填型、隐爆角砾岩型。金矿石分角砾岩型、蚀变岩型、硫化物－石英脉型３类。蚀变类型主要有硅化,绢云母化、钾化、黄铁矿化。成矿作用分为早、中、晚期。找金的最佳指示元素组合为Ａｕ－Ａｓ－Ｂｉ－Ｍｏ－Ｃｏ－Ｎｉ。不同类型矿体Ｈ－Ｏ同位素组成相对稳定,总体属岩浆水范围。综合矿区地质地球化学特征研究认为,金厂金矿属于与中生代岩浆活动有密切关系的浅成中高温岩浆期后热液矿床。     

蒙古国那仁陶勒盖金矿床原生晕特征及深部预测

为预测和评价那仁陶勒盖金矿的成矿潜力,运用多元统计方法,结合地球化学各参数信息,对那仁陶勒盖金矿原生晕进行系统研究.结果显示:那仁陶勒盖金矿赋矿花岗闪长岩中Au、Ag、Bi等元素浓集克拉克值明显偏高,与那仁陶勒盖金成矿作用关系密切;矿石中Au与Sb、Cu、Pb、Ag、Hg、Zn、As、Bi等关系最为密切;矿体原生晕轴向分带序列出现尾晕元素W、Sn等与前缘晕元素As叠加的现象,同时(As+Sb)/(Bi+Mo)、100Sb/(Bi·Mo)等分带性指数出现转折,指示深部存在盲矿体.依据上述矿体原生晕特征,建立矿体叠加晕预测模型,预测盲矿体赋存位置在海拔710m以下的岩体与地层接触带附近.     

安家营子金矿土壤地球化学的试验研究

内蒙古安家营子金矿基岩与土壤微量元素地球化学对比和土壤中金的相态分析研究,指出Ｂｉ、Ａｕ、Ｃｕ、Ｐｂ、Ｍｏ、Ｗ和Ｈｇ为该区金矿最佳的指示元素。Ｂｉ能形成明显的衬度高比含矿带宽的异常;Ａｕ也能形成衬度高而与含矿带相近的异常;Ｃｕ、Ｐｂ、Ｍｏ、Ｗ、Ｈｇ皆可显示较明显的异常,但宽度均小于含矿带的宽度。因此,土壤地球化学找矿方法在该区是一种重要的有效的找矿方法     

半荒漠戈壁地区土壤地球化学找矿研究——以阿拉善右旗塔布格地区为例

内蒙古阿拉善塔布格地区主要地貌形态为荒漠、戈壁和山地,本文基于1∶1万土壤地球化学测量工作成果,系统总结了塔布格地区地质特征,并对研究区内元素含量、异常组合和土壤地球化学异常等特征进行研究,结果表明:Au、Ag、Pb异常强度高、规模大,具有明显的浓集中心和浓度分带,多元素异常套合好,且与地质构造对应,异常查证发现含金石英脉,Au、Ag、Pb为主要成矿元素,As、Sb、Bi、Hg、Sn、Cu、Mo、Zn、W为成矿指示元素。综合地质成矿背景及化探异常特征,在区内圈定两处以金为主的多金属找矿靶区,认为后续工作主攻矿种应为金,主攻矿化类型为与韧-脆性构造变形有关的构造热液型金多金属矿化。     

Comparison of U-spatial statistics and C–A fractal models for delineating anomaly patterns of porphyry-type Cu geochemical signatures in the Varzaghan district,NW Iran

The delineation of populations of stream sediment geochemical data is a crucial task in regional exploration surveys. In this contribution, uni-element stream sediment geochemical data of Cu, Au, Mo, and Bi have been subjected to two reliable anomaly-background separation methods, namely, the concentration-area (C–A) fractal and the U-spatial statistics methods to separate geochemical anomalies related to porphyry-type Cu mineralization in northwest Iran. The quantitative comparison of the delineated geochemical populations using the modified success-rate curves revealed the superiority of the U-spatial statistics method over the fractal model. Moreover, geochemical maps of investigated elements revealed strongly positive correlations between strong anomalies and Oligocene–Miocene intrusions in the study area. Therefore, follow-up exploration programs should focus on these areas.     

坦桑尼亚卢帕金矿田元素地球化学特征及其找矿意义

卢帕（Lupa）金矿田位于坦桑尼亚西南部,是仅次于北部维多利亚湖金矿田的重要产金区。通过区域1∶25万原生晕地球化学测量结合水系沉积物测量资料分析发现,本区Au元素在片麻岩、基性超基性岩和中性岩内相对富集且分异性较高,在花岗岩和变质沉积岩内则相对贫化,且分异性较差;本区与金矿化伴生的元素为Bi、Ag、Hg、Mo、Pb和W。结合Au成矿地质特征分析,认为矿田内金矿类型更倾向于造山型,且存在多期次叠加成矿的特点。因此建议在后期的勘查中应首要解析矿区构造,特别是剪切带构造。     

闽东北地区金银矿床的水系沉积物地球化学特征

闽东北地区位于政和—大埔断裂带东侧。在晚侏罗世—早白垩世,该地区经历了十分强烈的火山活动,形成了分布广泛、厚度巨大的陆相火山沉积岩系,其下伏基底地层中的迪口组与福建省金矿或矿化关系极为密切,是福建省重要的含金矿源层,有较好的成矿条件。水系沉积物异常重现性试验及元素的表生迁移研究表明,不同采样批次、不同季节、不同年份在相同采样介质和采样点获得的主要成矿元素异常重现性较好。与全国水系沉积物元素平均含量相比,Au、Ag、Pb、Zn异常较明显。水系沉积物元素异常统计揭示,Au、Ag、As、Sb的成矿能力评价最高。这种元素异常组合表明,与火山岩有关的金矿是本区最有利的成矿矿种,并在闽东北地区经钻探验证,取得了良好的找矿效果。     

黑龙江龙沟河-鲜花山地区水系沉积物测量地球化学特征及找矿远景

通过龙沟河-鲜花山地区1：5万水系沉积物测量工作,获得了较丰富的区域地球化学测量成果.利用变异系数、浓幅分位值、相关性和异常特征研究对11种元素进行了数理分析,分析元素的地球化学特征,发现Au、Ag、Mo、As、Sb为主成矿元素.结合异常分布和元素成矿特征优选出了2处成矿远景区,经槽探验证,双目咀金锑成矿远景区发现2条金矿化体.     

Material composition and geochemical characteristics of ores of the Malinovskoe gold-ore deposit (Primorskii Krai,Russia)

The mineral composition and geochemical characteristics of the ores of the Malinovskoe gold-ore deposit are studied by the data from mining works (ditches, cleanings, and boreholes). It is found that the ore–magma system of the deposit was formed in several stages of mineralization characterized by two phases of magmatism differing in age. In terms of the set of features (the geological–structural position of the deposit, as well as the material composition and geochemical characteristics of the ores), the deposit is attributed to the gold–tourmaline type of mineralization associated spatially and genetically with the “raremetal” granitoid magmatism. This type has not previously been found in Primorskii Krai. The studies of the material composition and geochemical characteristics of the ores allow us to ascertain the correlations between the elements along with the reasons of their origination. By analogy with other gold-ore formations of the Russian Far East, the mineralogical and geochemical model of the deposit is developed (Be–Sn–Cr–Ba–Au–Cu–Mo–Pb–V–Ti–Co–W–Ag–Bi–Ni–Mn–Sr–Zn–Sb–As modeling element series of vertical zoning), which enables us to estimate the levels of the erosion section of the ore bodies and to evaluate their prospects. It is found that the most productive associations in the deposit are the gold–bismuth geochemical association (Au–Ag–Bi–Cu–As–Co) and, to a lesser degree, the gold–tungsten association (W–Au–Ag–Cu–Bi–As).     

南岭地区钨矿床共（伴）生金属特征及其地质意义初探

南岭是世界上最重要的钨矿产地,南岭钨矿床中与钨共（伴）生的有色、稀有及贵金属种类很多,数量可观,也是我国重要的矿产资源。论述了南岭及其邻近地区众多钨矿床中与钨共生或伴生的锡、钼、铋、铌钽、铜、铅锌、金银、稀土等元素的不同状况和特征,其中锡、钼、铋是南岭钨矿床中最普遍最重要的共（伴）生元素,铌钽只在演化程度较高的花岗岩相关的钨矿床中伴生产出,铜、金作为钨矿床伴生金属的意义较小,而钨矿床中伴生的银、铅锌具有相当重要的意义。从元素地球化学性质、南岭的区域地背景、花岗岩演化、多期多阶段成矿作用等方面出发,分析和解释了它们之间相互共（伴）生的原因及差异性,探讨了其地质意义。     

The behavior of ore elements in oxidized heterophase chloride and carbonate–chloride–sulfate fluids of porphyry Cu–Mo(Au) deposits (from experimental data)

The spatial coexistence and synchronous formation of magmatogene porphyry Cu–Mo mineralization and epithermal gold mineralization are due to the genetic relationship between their formation processes. This relationship might be due to the generation of metal-bearing fluids of different geochemical compositions by the porphyry ore-magmatic system, which then participate in the formation of magmatogene porphyry Cu–Mo(Au) and associated epithermal gold deposits. Synthesis of fluid inclusions in quartz was performed for experimental study of the behavior of Cu, Mo, W, Sn, Au, As, Sb, Te, Ag, and Bi in heterophase fluids similar in composition and aggregate state to natural ore-forming fluids of porphyry Cu–Mo(Au) deposits. We have established that at 700 °C, a pressure decrease from 117 to 106 MPa leads to a significant enrichment of the gas phase of heterophase chloride fluid with Au, As, Sb, and Bi. The heterophase state of carbonate–chloride–sulfate fluids is observed at 600 °C and 100–90 MPa. It characterizes the highly concentrated liquid carbonate–sulfide phase–liquid chloride phase–low-density gas phase equilibrium. A decrease in the pressure of heterophase carbonate–chloride–sulfate fluid leads to a noticeable enrichment of its chloride phase with Cu, Mo, Fe, W, Ag, Sn, Sb, and Zn relative to the carbonate–sulfate phase. The processes of redistribution of ore elements between the phases of heterophase fluids can be considered a model of generation of metal-bearing chloride fluids, which occurs in nature during the formation of porphyry Cu–Mo(Au) deposits, as well as a model of generation of gas fluids supplying Au, Te, As, and other ore elements to the place of formation of epithermal Au–Cu and Au–Ag mineralization.© 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.     

新疆富蕴县希勒库都克钼铜矿床地球化学特征

通过对希勒库都克钼铜矿床的矿床地质、矿区地层、岩浆岩微量元素含量特征进行研究,认为下石炭统南明水组上亚组地层富集成矿元素,为矿区的主要含矿层位,该地层中强蚀变砂岩、凝灰质粉砂岩的成矿元素含量较高,为矿区的主要赋矿围岩。岩浆岩中成矿元素及主要伴生元素的含量特征显示,海西中晚期侵入的花岗闪长岩、花岗闪长斑岩和闪长斑岩（玢岩）与成矿作用密切,可能直接或间接提供了成矿物质来源。矿床在水平和垂直方向上均具有良好的分带特征,水平上由矿床中心向外呈现Mo、Cu（Au）、→V、Ti、Co、Cr、Ni、Mn、As、Sb、Hg、W、Sn、Bi→Ag、Zn、B、F的分带特征,垂向上自上而下呈现F、B、As（Cr、Ni）→Au、Cu、W（Mo、V、Co、Bi）→Mn（Au、V、Bi、Mo）的分带特征,对指导找矿具有一定意义。