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Kaveh Pazand Ardeshir Hezarkhani Mohammad Ataei Yousef Ghanbari 《Chemie der Erde / Geochemistry》2011,71(4):397-402
This research is based on the application of stream sediments to mineral exploration. Identifying the geochemical anomalies from background is a fundamental task in exploration geochemistry. This paper applied the element concentration–area (C–A) model, to separating the geochemical anomalies from background based on a fractal approach and for the compilation of geochemical mapping from stream sediment samples (n = 620) of the Ahar region (Iran), where some Cu mineralization occurs. Comparisons of the known copper occurrences against the anomalous area created using thresholds from C–A method illustrate these hits. All of known Cu mineralizations and moreover defines two extra Cu anomaly districts. Additional sampling (n = 186) around new Cu anomaly confirms this anomaly within the district. 相似文献
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通过对甘肃省陇南文康地区的地质背景分析,采用区域1:5万水系沉积物测量的17种常量元素含量数据,分别运用传统统计学方法、S-A（能谱密度-累计面积）多重分形滤波法,确定成矿元素（以Au为例）异常下限值,圈定化探异常。结果表明,与传统方法相比,S-A多重分形法所圈定的异常面积小、数量多,传统统计法圈定的面积较大;两种方法圈定的异常展布方向基本一致,与研究区内已知的矿点吻合度高。本次研究认为S-A多重分形法所圈定的异常基本位于传统方法所圈定异常的内带之中,重点突出,与矿床空间位置对应关系较好,便于野外开展工作。同时在传统异常周边提取了部分低背景区的弱异常,这些弱异常可作为下一步找矿工作的新靶区。 相似文献
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《Chemie der Erde / Geochemistry》2019,79(2):323-336
Delineation of mineralization-related geochemical anomalies of stream sediment data is an essential stage in regional geochemical exploration. In this study, principal component analysis (PCA) was applied to 12 selected elements to acquire a multi-element geochemical signature associated with Cu-Au mineralization in Feizabad district, NE Iran. The spatial distribution of enhanced multi-element geochemical signature of the second component (PC2) was modeled by different geostatistical procedures including variogram calculation, ordinary kriging (OK) and inverse distance weighting (IDW) interpolation techniques. Concentration-area (C-A) fractal and U-spatial statistics models were then applied to the continuous-value interpolated models for delineation of geochemical anomalies. Quantitative comparison of results based on the known mineral occurrences in the study area was carried out using normalized density index and success-rate curves. All generated models represent a high positive relation with known Cu (±Au) deposits in the study area, although, comparison of the results revealed that the OK-based U-spatial statistics model was superior to the rest of models. Besides, the low, moderate and high-intensity anomalies are spatially associated with geological-structural features in the study area. 相似文献
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西秦岭成矿带北亚带是重要的多金属成矿单元。为缩小找矿靶区,在常家山地区开展了1:2.5万水系沉积物测量工作,对采集到的1 141件样品中的Au、Ag、As、Sb、Bi、Cu、Pb、Zn、W、Mo 10种元素进行核密度估算等数理统计分析,结果显示它们的浓度高于全国水系和区域水系沉积物的平均值,表明研究区成矿潜力大。通过因子分析得到F1(Bi、Cu、Zn)、F2(Au、As、Sb)、F3(Ag、Pb)、F4(W、Mo)4个主因子。使用浓度-面积(C-A)分形模型得到各元素和因子的异常阈值,并利用克里金插值法得到相应的地球化学空间分布图;结合区域控矿因素和异常分布特征圈定出Hz1、Hz2、Hz3 3处综合异常,前缘晕、近矿晕和尾晕显示出自西北向东南分布的趋势。水系沉积物地球化学异常分析结果表明,区内构造控矿特征明显,北西方向的礼县—闾井断裂是常家山地区有利的找矿部位。 相似文献
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多重地球化学背景下地球化学弱异常增强识别与信息提取 总被引：1，自引：0，他引：1
为对钦州湾-杭州湾成矿带(南段)庞西垌地区地球化学数据进行异常识别研究与信息提取,利用含量-面积法(C-A)得出庞西垌地区成矿主元素的异常下限,得到各元素异常分布图,并与已知矿(床)点进行叠加分析,发现已知矿(床)点与C-A法分析得到的异常区基本吻合,可根据该异常区预测未知矿床,从而为该研究区矿产资源潜力评价提供依据。为进一步从研究区复杂的地球化学背景中分离出与成矿有关的地球化学异常,采用分形滤波技术(S-A)提取致矿异常。研究表明,S-A法可在C-A法揭示的区域异常的基础上更深层次地提取出与矿化有关的局部异常用以反映研究区的多重地球化学背景,S-A法可有效地使弱异常增强进而提取出致矿异常,为庞西垌地区探寻隐伏矿体提供依据。 相似文献
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《Chemie der Erde / Geochemistry》2021,81(4):125811
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. 相似文献
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A spatial analysis method for geochemical anomaly separation 总被引：2，自引：0，他引：2
Qiuming Cheng F.P. Agterberg G.F. Bonham-Carter 《Journal of Geochemical Exploration》1996,56(3):183-195
One purpose of using statistical methods in exploration geochemistry is to assist exploration geologists in separating anomalies from background. This always involves two types of negatively associated errors of misclassification: type I errors occur when samples with background levels are rejected as background; and type II errors occur when samples with anomalous values are accepted as background. A new spatial statistical approach is proposed to minimize errors of total misclassification using a moving average technique with variable window radius. This method has been applied for geochemical anomaly enhancement and recognition as demonstrated by a case study of Au and Au-associated data for 698 stream sediment samples in the Iskut River area, northwestern British Columbia. Similar results were obtained using the fractal concentration-area method on the same data. By employing spatial information in the analysis, the process of selecting anomalies becomes less subjective than in more traditional approaches. 相似文献
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在Sklearn的Python语言代码基础上,开发了基于孤独森林和一类支持向量机的多元地球化学异常识别方法程序。选择吉林省和龙地区为实验区,从1∶5万水系沉积物资料中提取地球化学异常。把实验区已知矿点的空间分布位置作为"地真"数据,绘制两种机器学习算法的ROC曲线并计算AUC值,用来对比两种方法的多元地球化学异常识别效果。研究结果表明:两种机器学习算法都能够有效识别多元地球化学异常,所提取的多元地球化学异常与已知矿点具有显著的空间关联性;孤独森林算法在数据处理耗时和多元地球化学异常识别效果方面略优于一类支持向量机。 相似文献
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多维分形模型不仅采用常规的低阶矩统计, 而且采用高阶矩统计对多维分形分布进行度量, 从而能较细致地刻划正常值以及异常值.地球化学元素的正常值往往服从统计学中的大数定量, 即满足正态分布或对数正态分布, 然而异常值会服从分形分布(Preato).介绍了多维分形领域中的最新发展以及在地球化学研究中特别是研究超常元素空间分布和富集规律中的应用.结果表明, 通常的统计方法只对应于多维分形围绕均值周围的局部特征.为了有效地研究异常值的分布和富集规律, 建议采用高阶矩统计方法和多维分形方法, 并给出了两种分析地球化学元素, 并突出异常值贡献的方法.这些方法不仅可应用于研究微量元素的空间分布和富集规律, 而且可以区分地球化学背景与矿化有关的异常值.还介绍了该方法在对加拿大B.C.省西北部Mitchell-Sulphurets地区金铜矿化蚀变带研究中的应用. 相似文献
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《Chemie der Erde / Geochemistry》2021,81(4):125774
Recognition of geochemical anomalies is a pivotal assignment in exploration projects. This study aims to delineate different AuCu geochemical anomalies using number-size (N-S) and concentration-area (C-A) multifractal models in the Siah Jangal area, SE Iran. In this research, lithogeochemical datasets were applied for the exploration of Au and Cu. A comparison between geochemical anomaly maps based on the N-S and C-A fractal models shows the N-S fractal modeling is a powerful tool for separation of weak elemental geochemical anomalies in all of sampling zones. Based on a comparison between the results of these two methods and field studies, the geochemical anomaly zones, defined by the N-S fractal model, are more accurate than those recognized by the C-A fractal model. The obtained results of the N-S and C-A fractal models have been interpreted with the extensive set of information including structural interpretation, geological and alteration data. Au and Cu mineralization in the Siah Jangal area are hosted mainly by Oligocene-Miocene sub-volcanic rocks, especially strongly altered porphyric quartz diorite, hornblende diorite and diorite. Moreover, the positive dependence between various alteration zones and high concentrations of Au and Cu proves that strongly anomalous areas are correlated with these alteration zones. High grade Au (> 1000 ppb) and Cu (>150 ppm) are associated with the altered sub-volcanic rocks in the northern, eastern, and SW parts of the study area. Therewith, the strong anomaly populations are mostly occurred within the fault and fracture systems in the study area. This is a promising signal because quartz-sulfide veins and veinlets are associated with such structures. 相似文献
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非线性矿床模型与非常规矿产资源评价 总被引：14，自引：6，他引：8
探讨了建立非线性矿床模型对难识别的非常规矿产资源评价的可能性.首先评述了非线性理论在成矿动力学和矿产勘查中的应用, 以及非常规矿床与非常规矿产资源评价的研究现状.然后引进了以岩浆结晶分异成矿作用为例的多维分形非线性成矿系统模型.在此基础上揭示了非线性成矿系统必然导致元素富集和聚集的奇异分布及矿床分布的广义自相似性规律.广义自相似性刻画了成矿的外在多样性和内在相似性.介绍了2种最新研究的“奇异分析”和“广义自相似性”异常分解方法.采用文中所建议的非线性矿床模型方法对加拿大北部Gowganda地区的热液型Co, Ni, Ag, As, Pb 5种元素矿产进行了预测和评价.结果表明, 以“广义自相似性”和“奇异分析”为基础的非线性矿床模型及GIS信息综合技术对非常规难识别矿产资源评价是有效的. 相似文献
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多重分形模型在区域地球化学异常分析中的应用探讨 总被引：8，自引：2，他引：6
地球化学异常分析是地球化学勘查中的重要环节, 对有效发现异常至关重要。但是, 在以往研究中, 研究者们多重视对成矿元素及其伴生元素正异常的研究, 忽视对由元素贫化而形成的负异常的研究。元素的负异常在地球化学勘查中具有与正异常同等重要的作用, 以往没有重视负异常的原因之一是缺乏有效发现此类异常的方法, 尤其是确定负异常上限的方法。本文以北山地区1: 20万峡东幅水系沉积物测量Ba数据为基础, 探讨了应用多重分形模型确定贫化元素负异常上限的可行性。结果发现, 利用含量-面积法、含量-求和法确定的Ba的异常上限, 有效圈定了辉铜山矿床产出地段Ba的负异常, 取得了预期成果。 相似文献
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Identifying geochemical anomalies from background is a fundamental task in exploration geochemistry. The Gangdese mineral district in western China has complex geochemical surface expression due to complex geological background and was chosen as a study area for recognition of the spatial distribution of geochemical elements and separating anomalies from background using stream sediment geochemical data. The results illustrate that weak anomalies are hidden within the strong variance of background and are not well identified by means of inverse distance weighted; neither are they clearly identified by the C–A method if this method is applied to the whole study area. On the other hand, singularity values provide new information that complements use of original concentration values and can quantify the properties of enrichment and depletion caused by mineralization. In general, producing maps of singularities can help to identify relatively weak metal concentration anomalies in complex geological regions. Application of singularity mapping technique in Gangdese district shows local anomalies of Cu are not only directly associated with known deposits in the central part of the study area, but also with E–W and N–E oriented faults in the north of the study area. Both types of anomalies should be further investigated for undiscovered Cu mineral deposits. 相似文献
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Single-element Anomaly Mapping from Stream Sediment Geochemical Landscapes Aided by Digital Terrain Analysis 
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下载免费PDF全文 The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration. The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data. To map anomalies in a discrete field model of such data, two corrections are required: background correction and downstream dilution correction. Topography and geomorphology are important factors in variations of element con... 相似文献
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为了快速获取印度尼西亚苏门答腊岛元素分布的详细情况,根据苏门答腊岛的地形及景观特征,以水系沉积物和土壤为采样介质,实施了覆盖全岛的1：100万低密度地球化学填图。详细介绍了1：100万低密度地球化学填图的野外工作方法、测试的元素及分析技术,根据测试结果制作了苏门答腊岛69种元素地球化学图,计算和分析了苏门答腊岛地球化学背景的特征参数。总结了苏门答腊岛不同成因类型组合元素的分布特征及规律,圈定了16处地球化学综合异常。结合主因子综合异常特征以及区内典型矿床(点)空间分布、规模,对苏门答腊岛主成矿元素综合异常进行了甲、乙、丙分类,包括6个甲级综合异常、4个乙级综合异常和6个丙级综合异常,并优选3处具有较好找矿潜力的甲级综合异常进行异常解释和讨论,认为HS7综合异常具有寻找SEDEX型铅锌矿的潜力,HS8和HS11综合异常具有寻找浅成低温热液型金银矿和矽卡岩型铜铅锌矿床的潜力,为苏门答腊岛深入开展矿产勘查提供参考和依据。 相似文献
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The separation of anomalies from geochemical background is an important part of data analysis because lack of such identifications might have profound influence on or even distort the final analysis results. In this article, 1 672 geochemical analytical data of 11 elements, including Cu, Mo, Ag, Sn, and others, from a region within Tibet, South China, are used as one example. Together with the traditional anomaly recognition method of using the iterative mean ±2σ, local multifractality theory has been utilized to delineate the ranges of geochemical anomalies of the elements. To different degrees, on the basis of original data mapping, C-A fractal analysis and singularity exponents, Sn differs from the other 10 elements. Moreover, geochemical mapping results based on values of the multifractal asymmetry index for all elements delineate the highly anomalous area. Similar to other 10 elements, the anomalous areas of Sn delineated by the asymmetry index distribute along the main structure orientations. According to the asymmetry indexes, the 11 elements could be classified into 3 groups: (1) Ag and Au, (2) As-Sb-Cu-Pb-Zn-Mo, and (3) Sn-Bi-W.This paragenetic association of elements can be used to interpret possible origins of mineralization, which is in agreement with petrological analysis and field survey results. 相似文献
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奇异性理论在个旧锡铜矿产资源预测中的应用: 成矿弱信息提取和复合信息分解 总被引：21，自引：4，他引：17
本研究的目的是应用非线性理论和高新信息处理技术获取矿产资源预测综合信息, 开展以有色金属和贵金属矿产资源潜力评价和预测靶区圈定, 提交个旧及周边地区矿产资源潜力分布图.围绕该研究任务, 重点开展了如何应用奇异性理论和方法, 对比个旧东西矿区的异同.由于区域构造和岩体分布等空间变化性, 导致东西区成矿背景存在较大差异, 受出露地表或近地表矿体分布和矿山开采的影响, 东西区的成矿异常强度和大小都存在较大差异, 东区总体呈高背景而西区为低背景, 因而, 对东西区的成矿信息对比研究和异常圈定相对困难.采用局部奇异性分析方法从地球化学分形密度的角度圈定了局部异常, 在东西区均较好地反映了致矿地球化学异常的分布, 同时采用广义自相似分析方法分解了综合地球化学异常和背景.结果表明, 东西区地球化学背景差异悬殊, 而局部异常具有显著的自相似性.据此在东西区同时圈定的局部异常具有内在的相似性和表现形式上的多样性, 以此为依据所圈定的靶区均具有找矿意义. 相似文献
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纳日宗地区位于南祁连岩浆弧和宗务隆山—夏河—甘加裂谷的接触部位,该区及其周边已发现金属矿床(点)10余处,具有良好的金、铅、铜矿找矿前景。以该区1∶5万水系沉积物测量的16种元素含量数据为基础,统计分析了水系沉积物地球化学参数、元素相关性、成矿有利度系数等指标,总结了元素组合、富集贫化规律及其与地质背景、地质构造与成矿作用的关系。区内主要富集元素为Sn、Pb、Bi、As、Sb,成矿有利度系数高的元素有As、Pb、W、Au、Bi、Sb。结果显示,水系沉积物元素异常沿NW—NWW向断裂构造分布,初步认为构造发育地段具有较好的Au、Pb、W找矿潜力。依据单元素异常特征和成矿地质条件,圈定综合异常74处,划分出3个找矿远景区,指出了各找矿远景区的找矿方向。 相似文献