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Abstract: In this paper, a tectonic–geochemical exploration model is constructed to support mineral exploration in the southeastern Yunnan mineral district, China. Fault systems are significant to mineralization in this district because faulting activities have confined magmatic activities into certain spatial scales and temporal stages, which provide both hydrothermal fluids and heat for mineralization within fracture zones. Analysis of fault density using the singularity theory to characterize development of fault systems suggests that spaces produced by faulting activities favored the migration of hydrothermal fluids and mineralization. In addition, the singularity theory is applied to examine singular distributed ore-forming elements. Principal component analysis was used to model the spatial distribution of enrichment of the association of ore-forming elements, which suggests that geochemical haloes are linked with characteristic hydrothermal mineralization in the study area. For modeling mineral prospectivity, student''s t-values were estimated by weights of evidence method to depict patterns of fault density and geochemical anomalies that are highly correlated with known mineral deposit occurrences in the study area. By overlaying these patterns, distributions of enrichments of associated ore-forming elements and spaces due to faulting that favored mineralization can be modeled and areas prospective for mineral exploration can be delineated. The consistency of the results with information from published documents demonstrates that the exploration model discussed in this paper is useful and effective for investigating geological issues related with faulting activities. [Copyright &y& Elsevier]

Abstract: A new hybrid exploratory data analysis method, fractal projection pursuit classification (FPPC) model, is developed on the basis of the projection pursuit (PP) and fractal models. In this model, objective classification results are obtained by applying the projection index on the basis of the number-size fractal model. The real-coded acceleration genetic algorithm (RAGA) is used to optimize the projection index to establish the optimum projection direction in the model. Stream sedimentary geochemical data, Gejiu Mining District, Yunnan Province, China, were chosen in a case study to demonstrate the processing data analysis using FPPC. The results show that the anomalies are associated with known mineral deposits in the eastern part of the Gejiu District, and correlated with faults and granite in the western part of the study area. It is demonstrated that FPPC can be a powerful tool for multi-factor classification analysis and provide an effective approach to identify anomalies for mineral exploration. [Copyright &y& Elsevier]

Abstract: In this paper, fractal and multifractal analyses are demonstrated as effective tools for mapping complexity in the spatial distribution of faults. Faults within the eastern part of Gejiu mining area, Yunnan province, west southern China were chosen to demonstrate mapping of the complexity of their spatial distributions using fractal and multifractal models. The results show that (1) the fractal dimensions of the spatial distributions of all faults, NW-trending faults, and NE-trending faults are 1.68, 1.49, and 1.42, respectively, indicating differences in spatial distributions of different sets of faults; (2) the fractal dimensions of the spatial distributions of faults in the four Sn fields in the Gejiu mining district, namely Malage, Gaosong, Laochang, and Kafang (arranged in the order of increasing proportions of surface-projected areas of Sn orebodies) are 1.38, 1.57, 1.65, and 1.41, respectively; and (3) complexity of the spatial distributions of faults, represented by fractal dimension, correlates well with surface-projected areas of Sn orebodies, and lengths of faults satisfy the multifractal statistical and singularity index α, which can be used to quantify the complexity of the spatial distributions of faults. [Copyright &y& Elsevier]

Abstract: Identifying granite intrusions in the southeastern mineral district of Yunnan (China) is an essential task in support of mineral exploration for sustaining Sn mineral resources in the area. That is because the Sn and Cu hydrothermal mineralizations in this district are associated with granite intrusions, as sources of both hydrothermal fluid and heat. In this paper, a new high-pass filter technique based on a singularity analysis was applied to gravity and aeromagnetic data to delineate local anomalies characterizing granite intrusions. A PCA was applied to stream sediment geochemical data of 39 trace elements and compounds to derive a new integrated geochemical variable representing an element association, indicating the presence of granite intrusions. This new integrated geochemical variable is positively correlated with K2O, Na2O, Al2O3, Zr, Th, U, and Sr and negatively correlated with MgO and Fe2O3. To further characterize the granite intrusions, PCA was applied to integrate the local gravity and aeromagnetic anomalies obtained through singularity analysis and the new integrated geochemical variable obtained through PCA. The results show that the presence of outcropping and buried granitic intrusions is indicated by the principal component with positive loadings on the integrated geochemical variable and gravity data singularity and negative loadings on aeromagnetic data singularity. The methodology proposed in this paper is useful and effective for geo-information extraction and for integration of multisource geo-information for predictive modeling in mineral exploration. [Copyright &y& Elsevier]

Abstract: The Heqing area, located in the Sanjiang ore belt, China, consists of the Beiya gold orefield related to the alkaline porphyry, the Emeishan volcanic mafic rocks and a series of sedimentary rocks. Thirty-nine elements of stream sediment samples taken in the 1:200,000 geochemical survey in the Heqing area can be classified into four groups using principal component analysis. Two fractal models, i.e., the concentration–area model and the number–size model, are applied in determination of the thresholds for the representative elements in the four groups. The thresholds obtained from the two models are similar. According to the thresholds, the element concentration distribution can be divided into 3 segments, each of them is mainly correlated to one type of rocks, including the alkaline porphyry related to gold-mineralized rocks, mafic rocks and sedimentary rocks. This paper reveals that the various geological events can be characterized by the different fractal models of element distribution. [Copyright &y& Elsevier]