金矿床地球化学找矿信息分析：以团结沟金矿为例

金矿床地球化学矿信息对金矿勘查具有重要意义。矿床原生晕特征反映了矿化的元素组合特征。团结沟金矿床主成矿期元素组合为Ａｕ，Ａｓ，Ｓｂ，是矿床的直接指示元素。矿床次生晕及分散流流特征对找矿提供重要的地球化学信息。     

金矿床地球化学找矿信息分析─—以团结沟金矿为例

金矿床地球化学找矿信息对金矿勘查具有重要意义。矿床原生晕特征反映了矿化的元素组合特征。团结沟金矿床主成矿期元素组合为Ａｕ、Ａｓ、Ｓｂ，是矿床的直接指示元素。矿床次生晕及分散流特征也对找矿提供重要的地球化学信息。     

山东牟平——乳山金矿带石英脉深部含(金)矿性的地球化学预测标志

牟平—乳山金矿带石英脉型金矿具有明显的地球化学垂直分带性,据此总结出了该金矿床的地球化学异常模式及最佳指示元素组合,确定了石英脉深部含矿性的地球化学预测系列及预测指标。     

钦-杭结合带南段庞西垌地区Ag-Au致矿地球化学异常信息识别与提取

基于分形与多重分形理论的非线性化探数据处理方法及以空间加权主成分分析模型为代表的地学多源信息融合技术,为致矿地球化学异常信息的识别和提取提供了有力的工具。本文以钦-杭结合带南段庞西垌地区1∶5万水系沉积物地球化学数据为例,研究如何综合运用多重分形局部奇异性与空间加权主成分分析这两种地学信息处理方法来识别和提取致矿地球化学异常信息。首先,采用滑动窗口的方法绘制了研究区与银金矿化关系密切的五种地球化学元素Au、Ag、Cu、Pb和Zn的局部奇异性指数图以增强局部弱缓异常信息。然后,在控矿条件分析的基础上,运用北东向断裂构造这一重要控矿要素对Ag-Au成矿作用的影响范围,即距离北东向断裂的距离,作为应变量来构建用于空间加权主成分分析的空间权重系数的计算模型,以此来突显化探样品在控矿地质条件约束下的空间相关性。进而,采用空间加权主成分分析方法来得到Au、Ag、Cu、Pb和Zn多元素奇异性指数值的组合异常(第一主成分因子得分)。结果表明:综合运用多重分形局部奇异性与空间加权主成分分析方法可以有效的识别和提取Ag-Au致矿地球化学异常信息,圈定具有示矿意义的多元素组合异常区。     

申家窑金矿床地气测量异常特征

河南申家窑金矿床属典型的蚀变破碎带型金矿,矿区大部分被第四系沉积物所覆盖。文章通过偏光显微镜与扫描电子显微镜观察、电子探针微区分析、矿石成分化学分析等方法,认为申家窑金矿床的主要金矿物为自然金和银金矿,主要载体矿物为石英、黄铁矿和方铅矿。作者在总结矿床矿物学特征的基础上,实验研究了地气测量在该隐伏矿床上方黄土覆盖层的勘查效果。地气测量使用泡塑为捕集介质,利用surfer软件绘制元素空间分布图。元素空间分布图表明Au具有明显的地球化学异常,同时Cu、Pb、Zn等成矿伴生元素也存在异常。综合矿床矿物学的研究结果和元素空间分布特征,认为地气测量异常为矿致异常,地气异常结果能够指示深部隐伏矿体的产状。地气测量方法作为深穿透地球化学找矿方法之一,在研究区能够反映深部矿化,可以应用于黄土覆盖区寻找隐伏矿床。     

新疆石英滩金矿床原生晕特征与隐伏矿预测

通过对新疆东天山石英滩金矿床L4矿体各开采中段及钻孔的岩石系统采样分析和计算统计,确定了该金矿床的地球化学原生晕指示元素的组合特征、轴向分带、横向分带和纵向分带.结合国内外对该类型金矿原生晕地球化学特征和分带性研究成果,建立了本区该类型金矿床轴向分带的理想模型,预测深部隐伏矿体的可能位置,为本区寻找和勘察隐伏金矿提供了较为可靠的地球化学依据.     

核主成分分析在地球化学元素组合异常圈定中的应用

地球化学元素作为成矿预测一种重要的数据源,其异常分析往往是进行下一步找矿工作的基础,也是确定找矿靶区一种重要技术手段。作者以青海省大柴旦镇柴达木山南坡一带为研究区,通过开展1:10 000土壤地球化学测量,共分析了Au、Cu、Pb、Zn、As、Sb六种元素,采用核主成分分析地球化学元素组合异常,并与主成分分析进行比较分析,从应用结果可以看出核主成分的降维效果更好。从异常等值线图可以看出,采用核主成分的异常区域分布更加集中,所圈定的元素组合异常与已知矿床点在空间上具有良好的对应关系,说明利用核主成分圈定元素组合异常能够较好地确认地球化学元素组合异常。     

贵州省沿河县耕地土壤元素地球化学特征及其特色耕地利用建议

本文基于沿河土家族自治县耕地质量地球化学调查评价项目野外调查数据资料,分析了耕地土壤元素在不同成土母岩及不同土壤类型的地球化学特征。在摸清耕地土壤地球化学特征的基础上,利用SPSS统计分析软件,对全县表层土壤样品22个元素(指标)进行因子分析,得到有代表性的7个因子成分,分析不同元素组合的区域分布基于何种因素,并对各主因子进行了地质解释:F1主因子代表的变量与地质背景密切相关;F2主因子代表的变量与土壤中的As、Mo、Se与有机质易形成络合物有关;F3主因子代表的变量与区域上常形成与矿产有关的地球化学异常有关;F4主因子代表的变量可能与人工施肥及植被有关;F5主因子代表的变量与铜矿床有关;F6主因子代表的变量与分布的地层岩性有关;F7主因子代表的变量与萤石矿有关。根据全县富硒、富锗特色耕地分布特征及农产品优势,建议优先开发塘坝镇、新景镇等4个区域,为沿河县调整农业种植结构、发展现代山地特色优质农产品提供地球化学依据。     

云南罗平-开远成矿带金矿地质特征与找矿预测

通过对罗平-开远成矿带主要金矿床的地质-地球化学特征及其成矿规律的研究,提出罗平-开远成矿带金成矿具有"5带2区3层楼"特征,为区域金矿床地质-地球化学预测研究提供了理论依据。探讨了区内微细粒浸染型金矿床的主要类型,建立了地质-地球物理-地球化学综合信息的金矿找矿标志,并进行了找矿预测,预测结果反映区内具有较大的金矿资源找矿潜力。     

川北-甘南地区类卡林型金矿床的地质-地球化学特征

川北的联合村金矿和甘南的阳山金矿均为类卡林型金矿床.金矿形成于松潘-甘孜褶皱带与秦岭(华北)被动陆缘沉积构造活动带的对接部位.矿石类型不仅有各类沉积岩型,并有同等比例的蚀变脉岩型.金矿物粒径小于0.1μm.单体金占总含金量的91.6%,为易选金矿石.金矿床具有Au,Ag,As,Sb,Hg,Cu,Pb,Zn,Tl,Se,Te,Mo,Ba低温元素组合及丰度.除金矿床的容矿岩石与卡林金矿有所区别外,区内金矿床的地质-地球化学特征与美国卡林型金矿床相似.     

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.     

Introducing a new approach of geochemical anomaly intensity index (GAII) for increasing the probability of exploration of shear zone gold mineralization

Increasing the prediction rate in the identification of mineralization zones using the stream sediment geochemical data is an essential issue in the regional exploration stage. The various univariate (such as fractal and probability plot (PP) methods) and multivariate methods (such as principal component analysis (PCA)) have been performed for interpreting the geochemical data and detecting the mineralization areas. In this study, a new geochemical criterion named geochemical anomaly intensity index (GAII) was proposed for geochemical anomaly mapping. This approach was developed based on the PCA method and the catchment basin coefficient (CBC). The GAII as a weighted geochemical index is calculated using the mineralization principal component (MPC) scores and CBC. GAII can be mapped and utilized for geochemical anomaly mapping and detecting the mineralization areas. Besides, GAII can identify paragenesis elements better than the current methods. In this research, GAII was successfully used to generate geochemical anomaly maps on shear zone gold mineralization in the southwest of Saqqez, NW Iran. The geochemical data have been divided into three groups based on catchment basins and the host rock type. Then the MPCs and paragenesis elements of Au mineralization have been obtained individually using PCA. Three mineralization paragenesis groups consisting of (Au, Sn), (Au, W), and (Au, As, Sb and Ba) have been recognized for different catchment basins of the southwest of Saqqez district using PCA. GAII was calculated and mapped based on the CBC_{(Au, Sn)}, CBC_{(Au, W)}, CBC_{(Au, As, Sb, Ba)}, and their MPC scores. GAII accurately detected the Au mineralization zones and improved the geochemical anomaly map in this area compared to the PP method, concentration-area fractal model, and U-spatial statistics method. The results demonstrated that GAII was successfully used for (a) identifying the mineralization paragenesis elements, (b) intensifying the geochemical anomaly, and (c) increasing the prediction rate of mineralization zones. The shear zone gold mineralization areas in the southwest of Saqqez district were effectively detected using this new data analysis approach. GAII has provided better results than the current PP method, concentration-area fractal model, and U-spatial statistics method.     

拉脊山东段地区Au、Cu地球化学组合异常识别与提取

为削弱拉脊山东段地区化探数据(典型的成分数据)存在的闭合效应,进一步分析该区地球化学元素空间组合分布规律,使用等距对数比变换(ilr)"打开"水系沉积物地球化学数据;采用稳健主成分分析(RPCA)构建组合模型,用于识别组合地球化学异常;通过S-A分形滤波技术强化弱异常并分离异常与背景,圈定地球化学致矿异常,进一步指导矿产勘查.研究结果表明:得到两组与矿化相关的元素组合,第一组为Au-As,与研究区的构造蚀变岩型金(砷)矿(金源东沟等)相关;第二组为Cu-Ni,与区域内铜镍硫化物矿床(拉水峡等)相关.S-A滤波技术可以进一步分解组合异常,强化弱小异常,同时能够缩小强背景下的异常面积,结合研究区地质概况和分解后的异常图可以进一步指导该地区构造蚀变岩型Au(As)矿和铜镍硫化物矿床的找矿勘查工作.     

Sequential Factor Analysis as a new approach to multivariate analysis of heterogeneous geochemical datasets: An application to a bulk chemical characterization of fluvial deposits (Rhine–Meuse delta, The Netherlands)

Sequential Factor Analysis (seqFA) is presented here as an enhanced alternative to multivariate factorial techniques including robust and classical Factor Analysis (FA) or Principal Component Analysis (PCA). A geochemical data set of 145 sediment samples from very heterogeneous, mainly riverine, deposits of the Rhine-Meuse delta (The Netherlands) analyzed for 27 bulk parameters was used as a test case. The innovative approach explicitly addresses the priority issues when performing PCA or FA: heterogeneity and overall integrity of the data, the number of factors to be extracted, and which optimum minimal set of key variables to be included in the model. The stepwise decision process is based on quantitative and objectively derived statistical criteria, yet also permitting arguments based on geochemical expertize. The results show that seqFA, preferably in combination with robust methods, yields a highly consistent factor model, and is favorable over classical methods when dealing with heterogeneous data sets. It optimizes rotation of the factors, and allows the extraction of less distinct factors supported by only a few variables, thus uncovering additional geochemical processes and properties that would easily be missed with other approaches. The identification of key variables simplifies the geochemical interpretation of the factors, and greatly facilitates the construction of a geochemical conceptual model. For the case of the fluvial deposits, the conceptual model effectively describes their bulk chemical variation in terms of a limited number of governing processes.     

Application of K-means and PCA approaches to estimation of gold grade in Khooni district (central Iran)

Grade estimation is an important phase of mining projects, and one that is considered a challenge due in part to the structural complexities in mineral ore deposits. To overcome this challenge, various techniques have been used in the past. This paper introduces an approach for estimating Au ore grades within a mining deposit using k-means and principal component analysis (PCA). The Khooni district was selected as the case study. This region is interesting geologically, in part because it is considered an important gold source. The study area is situated approximately 60 km northeast of the Anarak city and 270 km from Esfahan. Through PCA, we sought to understand the relationship between the elements of gold, arsenic, and antimony. Then, by clustering, the behavior of these elements was investigated. One of the most famous and efficient clustering methods is k-means, based on minimizing the total Euclidean distance from each class center. Using the combined results and characteristics of the cluster centers, the gold grade was determined with a correlation coefficient of 91%. An estimation equation for gold grade was derived based on four parameters: arsenic and antimony content, and length and width of the sampling points. The results demonstrate that this approach is faster and more accurate than existing methodologies for ore grade estimation.     

安徽庐枞盆地泥河玢岩型铁矿床地质-原生晕地球化学找矿模型

开展长江中下游地区玢岩型铁矿床轴向原生晕地球化学分析及建模,可弥补地球物理勘探结果的多解性及探测精度的局限性,对定位和评价深部盲矿体具有至关重要的作用。文章在以往研究的基础上,开展庐枞盆地泥河玢岩型铁矿床钻孔原生晕的研究工作,采用多元统计分析方法,查明了主要成矿指示元素在不同地质体中的富集和亏损,确定了磁铁矿、硫铁矿和硬石膏矿体的矿中、近矿及远矿指示元素组合,结合矿床成因模型,建立了泥河玢岩型铁矿床地质-原生晕地球化学找矿模型,通过罗河和小包庄玢岩型铁矿床的佐证,认为该模型可以应用于长江中下游成矿带玢岩型铁矿床的勘探工作中。     

西秦岭寨上金矿地球化学特征及其找矿意义

通过对寨上金矿区30余个钻孔10种元素化探数据利用GEOEXPL软件进行处理统计,在SURFER及MAPGIS软件平台作图,并对寨上金矿床地质、地球化学异常及其元素轴向分带规律的综合研究,建立了该矿床的地质-地球化学找矿标志及其找矿模型,以期为矿床外围及深部找矿评价提供地球化学依据。     

桂东大瑶山成矿带古木口金矿床地质特征及找矿方向

古木口金矿是在桂东大瑶山成矿带上发现的首例中型规模以上高品位金矿,其矿床类型属于中低温岩浆热液型。该金矿矿体呈似层状、脉状、透镜状产出,受断裂、成矿结构面及构造蚀变带控制,矿床在垂向和横向上具有石英脉型、破碎蚀变岩型及斑岩型分带特征。为及时总结矿区勘查新成果,推动该区找矿新突破,研究矿体与寒武系含碳细碎屑岩系、层间引张型走滑转换断裂、花岗闪长斑岩组合要素的空间关系,以及近矿围岩蚀变矿物组合标志、土壤化探异常等成矿综合信息;运用土壤地球化学测量及异常带槽探、钻探揭露等综合找矿方法,在总结分析了矿区地质-地球化学特征及矿化时空分布规律的基础上,提出了该区带的找矿方向。结果显示,该矿区深部及外围具有较好的找矿前景,特别是北西向断裂、引张型走滑转换断裂、伸展型脆-韧性剪切异常带利于寻找破碎带蚀变岩型富金矿,其构造相对封闭环境的深部是寻找斑岩型金矿的有利地段。     

吉林白山地区金矿综合信息找矿模型

以吉林省白山地区金矿产为预测矿种, 以金矿床为目标物, 在前人对该地区地质研究成果的基础上, 系统分析了地层、岩浆岩和构造等地质条件与金矿产的关系, 查明了各种地质条件对金矿产的控制作用。同时利用地质、化探和物探等相关数据, 对该地区进行了金成矿综合信息矿产预测, 建立了以中元古代地层为主要成矿地层, 北东向和北西向断裂为主要控矿构造, 航磁解译环形构造和重力高背景场为主要成矿标志, 以及化探元素呈现三种组合异常等因素的吉林白山地区综合信息找矿模型。