混合模糊证据权模型在河北承德煤炭资源预测中的应用

应用模糊逻辑法、加权证据权法相结合的混合模糊证据权模型和GeoDASGIS技术开展了承德煤炭资源预测研究。采用模糊逻辑法对与煤炭矿床有关的证据层进行了系统的处理和分析,并在此基础上采用加权证据权方法编制了成矿后验概率图,最终划分出5个主要的找矿远景区。研究结果不仅对进一步开展预测区优选评价具有重要的参考意义,而且为混合知识驱动与数据驱动的混合预测模型提供了一种可借鉴的有效方法。     

Fuzzy logic mineral potential mapping for copper exploration using multi-disciplinary geo-datasets,a case study in seridune deposit,Iran

This paper describes the application of the knowledge-based fuzzy logic method to integrate various exploratory geo-dataset in order to prepare a mineral prospectivity map (MPM) for copper exploration. Different geophysical layers which are derived from the magnetic and the electrical surveys, along with the ones extracted from the background geology (i.e., lithology, fault and alteration) and geochemical data are incorporated in such process. Seridune copper deposit located in the Kerman province of Iran is the case study to delineate its high potential zones of Cu-bearing mineralization for drilling additional boreholes. Four layers from the magnetic data involving upward continuation, analytic signal, reduced to pole and pseudo gravity are assigned in the multi-disciplinary geo-dataset to locate the intrusive complexes responsible for Cu mineralization. The apparent resistivity, chargeability and sulfide factor layers acquired from geo-electrical data are also included in the final preparation of MPM. Then the normalized weights of seven geophysical, three geological and one geochemical evidential layers as main criteria are determined based upon the knowledge of expert decision makers. Fuzzy operators (i.e., Sum and Gamma) are applied to integrate these exploratory features. To evaluate the performance and applicability of the approach, the productivity of the drilled boreholes (Cu concentration multiplied by ore thickness) are used to validate the produced MPMs. It is shown that an optimum correlation coefficient of 0.86 exists between the MPM values and Cu productivity criterion along drilled boreholes.     

基于遥感手段的高寒山区矿产资源远景区快速圈定与综合评价技术集成

[研究目的]新疆西昆仑地区是中国重要的成矿带,海拔高、气候恶劣、地形切割强烈,开展找矿工作极其困难,急需一套高效找矿技术体系实现找矿突破.[研究方法]本文利用TM、ETM+、OLI、ASTER、高分1号与2号、WorldView-2/3等卫星数据,采用雷达图像与光学图像的融合技术、改进的Crosta方法(iCrosta...     

Fuzzy cluster analysis in geochemical exploration

As a classification method, cluster analysis has been widely used in geology and geochemical exploration, but sometimes the results of clustering were difficult to interpret, or missclassification of geochemically similar members into entirely different clusters might occur. The reason for this is suggested and discussed. A new technique, fuzzy clustering is introduced. Comparision of the results of fuzzy clustering with conventional clustering using a set of hypothetical data is made. An example of a practical application indicating the apparent merits of fuzzy clustering is given. This technique might show great promise when applicated to geochemical exploration problems.     

Omnibus Weights of Evidence Method Implemented in GeoDAS GIS for Information Extraction and Integration

Weights of evidence (WofE) is an artificial intelligent method for integration of information from diverse sources for predictive purpose in supporting decision making. This method has been commonly used to predict point events by integrating point training layer and binary or ternary evidential layers (multiclass evidence less commonly used). Omnibus weights of evidence integrates fuzzy training layer and diverse evidential layers. This method provides new features in comparison with the ordinary WofE method. This new method has been implemented in a geographic information system-geophysical data analysis system and the method includes the following contents: (1) dual fuzzy weights of evidence (DFWofE), in which training layer and evidential layers can be treated as fuzzy sets. DFWofE can be used to predict not only point events but also area or line events. In this model a fuzzy training layer can be defined based on point, line, and areas using fuzzy membership function; and (2) degree-of-exploration model for WofE is implemented through building a degree of exploration map. This method can be used to assess possible spatial correlations between the degree of exploration and potential evidential layers. Importantly, it would also make it possible to estimate undiscovered resources, if the degree of exploration map is combined with other models that predict where such resources are most likely to occur. These methods and relevant systems were validated using a case study of mineral potential prediction in Gejiu (个旧) mineral district, Yunnan (云南), China.     

地理信息系统在评价冀东地区绿岩型金矿资源中的应用

本文应用地理信息系统（ＧＩＳ）对冀东地区的地质、地球化学数据和地球物理、遥感解释资料（包括１∶５０万地质图，１∶２０万水系沉积物和１∶１００万地球物理、遥感）的推断成果，进行了综合分析。应用专家知识和统计规律建立起该区以地球化学为主要特征的绿岩型金矿的预测模型，并利用逻辑运算和贝叶斯规则把各种资料（反映绿岩型金矿的特征）有机地结合起来。采用地理信息系统空间分析有效手段，编制出了研究区绿岩型金矿预测图。以概率的形式表示金矿的潜在远景区，明确地证明了区内已知的大中型和小型矿区和高概率区是相符的，同时指示出一些有意义的靶区，为进一步勘探提供了证据     

A hybrid AHP-VIKOR approach for prospectivity modeling of porphyry Cu deposits in the Varzaghan District,NW Iran

Identifying highly favorable areas related to a particular mineralization type is the main objective of mineral prospectivity modeling (MPM). The northwestern portion of Ahar-Arasbaran porphyry copper belt (AAPCB) is situated within the Urumieh-Dokhtar magmatic belt (UDMB). Because of owning many worthwhile Cu-Mo and Cu-Au porphyry deposits, this area is entitled to incorporate diverse spatial evidence layers for the MPM. In this paper, a hybrid AHP-VIKOR, as an improved knowledge-driven MPM procedure has been proposed for integration of various exploration evidence layers. For this, the AHP is used to calculate important weights of spatial criteria while the VIKOR is applied to outline ultimate prospectivity model. Six effective spatial evidence layers pertaining to the Varzaghan District are selected: (1) multi-elemental geochemical layer of Cu-Mo-Bi-Au; (2) remotely sensed data of argillic, phyllic, and iron oxide alteration layers; and (3) geological and structural layers of Oligo-Miocene intrusions and fault. In addition, a fuzzy prospectivity model (γ?=?0.9) is implemented to assess the AHP-VIKOR approach. Two credible validation methods comprising normalized density index and success rate curve are adapted for quantitative evaluation of predictive models and enhancing the probability of exploration success. The achieved results proved the higher accuracy of the AHP-VIKOR model compared with the fuzzy model in delimiting the favorable areas.     

Data fusion and porphyry copper prospectivity models,southeastern Arizona

Mineral exploration programs commonly use a combination of geological, geophysical and remotely sensed data to detect sets of optimal conditions for potential ore deposits. Prospectivity mapping techniques can integrate and analyse these digital geological data sets to produce maps that identify where optimal conditions converge. Three prospectivity mapping techniques – weights of evidence, fuzzy logic and a combination of these two methods – were applied to a 32,000 km² study area within the southeastern Arizona porphyry Cu district and then assessed based on their ability to identify new and existing areas of high mineral prospectivity. Validity testing revealed that the fuzzy logic method using membership values based on an exploration model identified known Cu deposits considerably better than those that relied solely on weights of evidence, and slightly better than those that used a combination of weights of evidence and fuzzy logic. This led to the selection of the prospectivity map created using the fuzzy logic method with membership values based on an exploration model. Three case study areas were identified that comprise many critical geological and geophysical characteristics favourable to hosting porphyry Cu mineralisation, but not associated with known mining or exploration activity. Detailed analysis of each case study has been performed to promote these areas as potential targets and to demonstrate the ability of prospectivity modelling techniques as useful tools in mineral exploration programs.     

Incorporating conceptual and interpretation uncertainty to mineral prospectivity modelling

Prospectivity analyses are used to reduce the exploration search space for locating areas prospective for mineral deposits.The scale of a study and the type of mineral system associated with the deposit control the evidence layers used as proxies that represent critical ore genesis processes.In particular,knowledge-driven approaches(fuzzy logic)use a conceptual mineral systems model from which data proxies represent the critical components.These typically vary based on the scale of study and the type of mineral system being predicted.Prospectivity analyses utilising interpreted data to represent proxies for a mineral system model inherit the subjectivity of the interpretations and the uncertainties of the evidence layers used in the model.In the case study presented,the prospectivity for remobilised nickel sulphide(NiS)in the west Kimberley,Western Australia,is assessed with two novel techniques that objectively grade interpretations and accommodate alternative mineralisation scenarios.Exploration targets are then identified and supplied with a robustness assessment that reflects the variability of prospectivity value for each location when all models are considered.The first technique grades the strength of structural interpretations on an individual line-segment basis.Gradings are obtained from an objective measure of feature evidence,which is the quantification of specific patterns in geophysical data that are considered to reveal underlying structure.Individual structures are weighted in the prospectivity model with grading values correlated to their feature evidence.This technique allows interpreted features to contribute prospectivity proportional to their strength in feature evidence and indicates the level of associated stochastic uncertainty.The second technique aims to embrace the systemic uncertainty of modelling complex mineral systems.In this approach,multiple prospectivity maps are each generated with different combinations of confidence values applied to evidence layers to represent the diversity of processes potentially leading to ore deposition.With a suite of prospectivity maps,the most robust exploration targets are the locations with the highest prospectivity values showing the smallest range amongst the model suite.This new technique offers an approach that reveals to the modeller a range of alternative mineralisation scenarios while employing a sensible mineral systems model,robust modelling of prospectivity and significantly reducing the exploration search space for Ni.     

黔西南金矿勘查地球化学30年:回顾与展望

勘查地球化学是快速寻找黔西南金矿的重要方法和技术手段.30年来,根据勘查地球化学圈定的金异常,为找寻肉眼难以识别的微细浸染型金矿提供了重要找矿线索和直接找矿靶区,并取得显著的找矿效果.黔西南金矿勘查地球化学的历史和研究表明,该区金的成矿地球化学条件优越,金地球化学块体内部结构及其套合的地球化学模式谱系预示尚有较大资源远景和找矿潜力.勘查地球化学需要结合地质、物探、遥感等方法,在新深度、新理论、新领域上进一步指导地质找金工作,才能不负时代所赋予的历史使命.     

模糊逻辑法在秦岭-松潘成矿区金矿潜力预测中的应用

在介绍模糊逻辑的基本理论、详细分析秦岭-松潘地区金成矿规律的基础上,应用ArcView GIS及其扩展模块Arc-SDM对研究区地质、地球化学、地球物理等数据进行处理,提取预测变量。已知的金矿（点）被用来构造研究区隶属度函数,确定各预测变量的隶属度大小。根据不同预测变量与金矿的相关性大小,选择不同的模糊算子进行综合,生成控矿因子。最后应用伽马算子,综合控矿因子,得到最终的秦岭-松潘金矿潜力图。根据金矿潜力图和模糊逻辑模型的检验结果,说明模糊逻辑可以对空间数据进行有效的综合,预测潜力图件中圈出的有利矿化区,可用于进一步勘查研究。     

基于MORPAS的证据权重法在沽源盆地铀成矿预测中的应用

文章在对沽源盆地内的地质、物化探等信息与铀成矿的关系进行深入分析的基础上,借助MORPAS平台,对区内各控矿要素定量化,利用GIS的空间分析功能提取了断裂Buffer、潜火山岩Buffer、航磁异常等在内的16个证据图层,并将研究区划分为1 km×1 km大小的9 562个单元,利用证据权重法对研究区铀矿进行预测,圈定了3级成矿远景,为该区进一步找矿指出了方向.     

Application of fractal content-gradient method for delineating geochemical anomalies associated with copper occurrences in the Yangla ore field,China

Fractal and multi-fractal content area method finds application in a wide variety of geological, geochemical and geophysical fields. In this study, the fractal content-gradient method was used on 1:10,000 scale to delineate geochemical anomalies associated with copper mineralization. Analysis of geochemical data from the Yangla super large Cu-Pb-Zn polymetallic ore district using the fractal content-gradient method, combined with other geological data from this area, indicates that ore-prospecting in the ore district should focus on Cu as the main metal and Pb-Zn and Au as the auxiliary metals. The types of deposits include (in chronological order) re-formed sedimentary exhalative (SEDEX), skarns, porphyries, and hydrothermal vein-type deposits. Three ore-prospecting targets are divided on a S–N basis: (1) the Qulong exploration area, in which the targets are porphyry-type Cu deposits; (2) the Zongya exploration area, where the targets are porphyry-type Cu and hydrothermal vein-type Cu-Pb polymetallic deposits; and (3) the Zarelongma exploration area, characterized mainly skarn-type “Yangla-style” massive sulfide Cu-Pb deposits. Our study demonstrates that the fractal content-gradient method is convenient, simple, rapid, and direct for delineating geochemical anomalies and for outlining potential exploration targets.     

基于GIS的证据权模型在秦岭～松潘金矿潜力预测中的应用

数据驱动的证据权法被用来进行金矿潜力制作。为了确定秦岭~松潘金矿的潜力区,需利用地质、地球化学、地球物理等数据。数据采集、图形处理、空间分析都是在GIS平台上进行的。预测结果表明,证据权法在综合不同空间数据上是有效的,最终的预测图件圈出了最有利的矿化区,可用于进一步勘查研究。     

Integration multisource data for mineral exploration by using fuzzy logic,case study: Taknar deposit,NE of Iran

The Taknar Zone is located at the northern margin of the eastern Iranian continental microplate, and it is host to the Taknar massive sulfide deposit. This study was conducted to find new exploration targets. We used multiple data sources (e.g., litho-geochemical and magnetic surveys) to produce more effective predictive maps. Principal component analysis and hierarchical cluster analysis methods were used to organize the new information into favorability maps and to determine multi-element correlations. We then employed fuzzy logic modeling to create favorability maps from geochemical and magnetic data. A concentration–area multifractal method was used to evaluate the final integrated favorability map for massive sulfide exploration. Our new map identifies previously unexploited sites in the eastern part of the study area, near the boundary of the Taknar formation, with intrusive and subvolcanic rocks, with potential for mineral exploration. The newly defined targets are attractive because old mined ore bodies are also identified in the favorability map.     

模糊证据权方法在镇沅(老王寨)地区金矿资源评价中的应用

采用模糊证据权方法和GeoDASGIS技术开展了镇沅(老王寨)及其邻区的金矿资源潜力评价.分别采用GeoDASGIS软件提供的局部奇异性分析技术、S-A异常分解技术、主成分分析技术、证据权、模糊证据权等技术对相关地球化学元素进行了系统的处理和分析.应用主成分分析方法确定了可能的2种不同成矿类型,并采用主成分得分确定了组合异常点,在此基础上分别采用普通证据权和模糊证据权方法编制了成矿后验概率图,圈定了有利成矿地段.对比普通证据权方法与模糊证据权方法所得结果表明,模糊证据权方法可减小图层离散化造成的有用信息损失,提高预测结果精度.     

桂中1井井中化探指标的异常特征和指示意义

井中化探作为一种新的油气监测和早期盆地勘查评价的地球化学技术越来越引起人们的关注,文章优选了酸解烃（SC1-SC4）、热释烃（RC1-RC4）、二维荧光（FL327、FL327、FL399）、后生碳酸盐（△C）和热释汞（Hg）等作为评价指标,通过对桂中1井各种化探指标的异常特征分析,表明区内存在油气生成潜力,并指出了其主要生油气层段和储油气层段。     

A comprehensive VIKOR method for integration of various exploratory data in mineral potential mapping

The central Iranian volcanic-sedimentary belt in Kerman province of Iran that is located within the Urumieh-Dokhtar magmatic arc zone is chosen to integrate diverse evidential layers for mineral potential mapping. The studied area has high potential of mineral occurrences especially porphyry copper, and the prepared potential maps aim to outline new prospect zones for further investigation. Two evidential layers including the downward continued map and the analytic signal of filtered magnetic data are generated to be used as geophysical plausible traces of porphyry copper occurrences. The low values of the resistivity layer acquired from airborne frequency domain electromagnetic data are also used as an electrical criterion in this study. Four remote sensing evidential layers including argillic, phyllic, propylitic, and hydroxyl alterations are extracted from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images in order to map the altered areas associated with porphyry copper deposits. The Enhanced Thematic Mapper Plus (ETM+) images are used as well to prepare iron oxide layer. Since potassic alteration is generally the mainstay of copper ore mineralization, the airborne potassium radiometry data is used to explore both phyllic and potassic alteration. Finally, the geochemical layers of Cu/B/Pb/Zn elements and the main geochemical component responsible for ore mineralization extracted from principal component analysis are included in the integration process to prepare final potential maps. The conventional and the extended version of VIKOR method (as a well-known algorithm in multi-criteria decision making problems) produced two mineral potential maps, and the results were compared with the ones acquired from prevalent methods of the index overlay and fuzzy logic operators of sum and gamma. The final mineral potential maps based upon desired geo-data set indicate adequately matching of high potential zones with previous working and active mines of copper deposits.     

模糊评价方法在油气化探中的应用

油气化探指标的处理与综合评价是油气化探工作中的重要组成部分,它直接关系到油气化 探找油气藏效果。模糊评价是利用模糊数学中的模糊关系原理,结合已知探区油气化探指标在油气藏 上方或油气藏储层的规律性变化,找出反映油气藏属性的信息,结合地质环境资料,建立模糊评价系 统,对该探区化探指标异常进行评判。