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Browsing Geology by Author "Carranza, Emmanuel John Muico."

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    Developments in GIS-based mineral prospectivity mapping : An overview.
    (Bureau de Recherches Géologiques et Minières (French Geological Survey), 2017-10) Carranza, Emmanuel John Muico.
    This keynote presentation provides an overview of the developments in GIS-based mineral prospectivity mapping during the past 30–40 years or so.
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    The efficiency of logistic function and prediction-area plot in prospectivity analysis of mineral deposits.
    (Bureau de Recherches Géologiques et Minières (French Geological Survey)., 2017-10) Yousefi, Mahyar.; Carranza, Emmanuel John Muico.
    In this work, we present logistic-based mineral prospectivity mapping (MPM) methods concerning with assigning weights of exploration indicators, without contribution of training sites as in supervised MPM and without using user-judged weights as in unsupervised MPM, to modulate the problems of stochastic and systemic errors. In addition, we discuss the ability of prediction-area plot as a tool to assess and compare evidential layers and prospectivity models.
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    Interaction between karst terrain and bauxites : evidence from Quaternary orebody distribution in Guangxi, SW China.
    (Scientific Reports., 2017-04-28) Yang, Lin.; Wang, Qingfei.; Zhang, Qizuan.; Carranza, Emmanuel John Muico.; Lui, Huan.; Liu, Xuefei.; Deng, Jun.
    Abstract available in PDF file.
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    Isotope geochemistry of Mississippi Valley Type strataboundF-Ba-(Pb-Zn) ores of Hammam Zriba (Province of Zaghouan, NETunisia).
    (Chemie der Erde., 2016-09-11) Jemmali, Nejib.; Carranza, Emmanuel John Muico.; Zemmel, Balkiss.
    Abstract available in PDF file.
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    Local-to micro-scale structural controls on shear-zone-hosted gold mineralisation, Ngubevu area, Natal Thrust Front, Tugela Terrane, South Africa.
    (2021) Chagi, Onele.; Carranza, Emmanuel John Muico.; Hoyer, Lauren.
    The research described in this dissertation focused on shear-zone-hosted precious and base metal mineralisation in the Ngubevu area, in the Natal Thrust Front of the Tugela Terrane in the Natal Metamorphic Province of South Africa. This province forms part of a 400-km-wide metamorphic belt referred to as the Namaqua-Natal Metamorphic Province, which stretches from the Northern Cape on the west coast to KwaZulu-Natal on the east coast of the country. Unlike the western Namaqualand Metamorphic Province, which is well-explored and well-exploited for several mineral deposits, the Natal Metamorphic Province is relatively poorly explored. One reason for this is that the nature of structural controls on mineralisation in the Natal Metamorphic Province is poorly understood. In the research described in this dissertation, known occurrences of shear-zonehosted precious and base metal deposits in the Golden Eagle and Champion Mines in the Ngubevu area, which have been described in the literature, were studied in the micro-scale, and the findings obtained were integrated with existing knowledge of regional- to local-scale deformation in the Tugela Terrane, in order to deduce the structural controls of such mineralisation in the area. The micro-scale data, studied by spatial analytical methods (i.e., point pattern analysis, Fry analysis, fractal analysis and shape analysis) show that the mineralisation in the area operated in at least two spatial scales, within each thin section sample, of at most 0.005 μm and at least 0.002 μm and that, within each thin section sample, the occurrence of shear-zone-hosted precious and base metal deposits is non-random as they exhibit clustered and/or regular spatial distributions. Microfractures in the area generally show major northerly trends in their alignments. Likewise, microscale mineral distributions show NNE–SSW and NNW–SSE trends in their orientations. These findings suggest that N–NE-directed compression controlled the occurrence and distribution of shear-zone-hosted precious and base metal mineralisation in the Ngubevu area. This N–NEdirected compression and thrusting during deformation (D1) controlled the circulation and concentration of mineralising hydrothermal fluids in the Natal Thrust Front. These hydrothermal fluids formed quartz veins along nearly E–W-trending foliations resulting in mineralisation in the clustered and regular spatial patterns observed in the micro-scale.
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    Prospectivity analysis of orogenic gold deposits in Saqez-Sardasht Goldfield, Zagros Orogen, Iran.
    (Ore Geology Reviews., 2017-03-02) Almasi, Alireza.; Yousefi, Mahyar.; Carranza, Emmanuel John Muico.
    Diverse deposit-types or mineral systems form by diverse geological processes, so translation of knowledge about the controls of mineralization acquired from the 4D geological modeling into 2D spatial predictor maps is a major challenge for prospectivity analysis. In this regard, mathematical functions have been used to model the conceptual or perceived spatial relationships between geological variables and targeted type or system of mineralization. In this paper, due to the different models of spatial relationships between predictors and mineral deposits, we investigated the performance of different fuzzification functions to quantify the relationships. We demonstrated that various types of relationships between exploration features and a mineralization-type sought could be quantified using different fuzzification functions for prospectivity analysis. We illustrated the process of the prospectivity analysis by using a data set of orogenic gold deposits in Saqez-Sardasht Goldfield, Iran. Prospectivity modeling of orogenic gold mineralization in the study area showed that the NE-SW trending targets have priority for further prospecting of the deposits.