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Thrust-related gold-bearing tourmaline-quartz veins: The Wrightbar mine, Val d'Or mining camp (Abitibi, Canada)
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
The Archean Abitibi Greenstone Belt (AGB), contains most of vein-type gold deposits of eastern Canada. In Québec, these gold deposits occur mostly in the Val d’Or Mining Camp (VOMC), which is located in the southern part of the AGB. Southward, the VOMC is limited by the E-W trending Larder Lake-Cadillac fault zone (LCF), which has been interpreted as a major structural control regarding the distribution of gold mineralization in the area. Gold deposits of the VOMC are genetically associated with steeply to moderately dipping reverse SZ (Robert 1990, Robert & Brown 1986, Belkabir et al. 1993, and others). Regional structural studies conducted to the recognition of several orders of SZ related to the regional D2 deformation (Robert 1990). The LCF is considered as a first order structure that is related to second and third order SZ. According to Robert & Brown (1986) and Robert (1990), third order SZ are host to most vein-type gold deposits of the area, such as the Sigma mine hosted by volcanic rocks of the Val d’Or Formation and other gold deposits hosted by the syn-volcanic BGB. Gold deposits of the BGB, such as the Ferderber, Perron, Beaufor, and Pascalis mines, have been extensively studied in the past (Belkabir et al. 1993, and others). However, the Wrightbar mine has not been studied until recently (Ferkous & Tremblay 1997, Ferkous et al. 1997), and shows a structural setting that is significantly contrasting with others deposits of the VOMC. In this paper, we describe the tectonic structures of the Wrightbar deposit that host gold-bearing veins, the geodynamic condition and timing of native gold deposition, and present a new genetic interpretation.
Mapping geological configuration using geophysics data: an investigative approach in targeting iron ore, gold mineralization and other commodities, a case study of Toko-Nlokeng area (Nyong Greenstone Belt, SW Cameroon)
Published in Applied Earth Science, 2023
Yannick Saturnin Evina Aboula, Joseph Mvondo Ondoa, Paul-Désiré Ndjigui
To see beyond the ground surface into the depth dimension has always been an aim of exploration and the mapping of geophysical anomalies caused by the entirety of the buried geology (rather than just the ore bodies) proves to be one of the most realistic methods of achieving this over large areas at modest cost. Multispectral satellite images have educated a large audience on the advantages of digitally processed and enhanced color imagery at the correct scale and projection over, for example, monochrome aerial photography in conventional hard copy. An example of lithologic mapping in the Abitibi Greenstone Belt, Canada, using airborne hyperspectral imagery (a magnetic anomaly image of Archaean granite-greenstone terrane in Western Australia’s Yilgarn Block (Rivard et al. 2009) and airborne used for the litho-structural analysis of the eburnean greenstone belts in Burkina Faso, west Africa (Metelka et al. 2011; El-Shazly et al. 2019). The method seems to be entering a new era of more extended application and many potential users are becoming aware of the capabilities of state-of-the-art gamma-ray spectrometer mapping, not only within exploration but for many other applications such as in soil mapping where the chemistry of the ground surface may be indicative.
VHMS mineralisation at Erayinia in the Eastern Goldfields Superterrane: Geology and geochemistry of the metamorphosed King Zn deposit
Published in Australian Journal of Earth Sciences, 2019
S. P. Hollis, D. Podmore, M. James, J. F. Menuge, A. L. Doran, C. J. Yeats, S. Wyche
The abundance of calculated normative corundum was used by Grunsky (2013) for rocks from the Abitibi greenstone belt, Canada. When Al is in excess over (Ca + Na + K), the presence of normative corundum may be interpreted as extensive alkali leaching, a characteristic feature of footwall alteration associated with VHMS deposits. At King, normative corundum abundance is highest in the chloritic feeder zone, but importantly is not present (i.e. >0) in any hanging-wall strata regardless of composition. This reflects the lack of alkali leaching in the hanging-wall and may be a useful tool to identify hydrothermal upflow zones associated with VHMS deposits, and also discriminate hanging-wall from footwall sequences. Normative quartz abundance generally parallels the Silicification Index trend but drops in weakly altered hanging-wall strata.
Cathaysian slivers in the Philippine island arc: geochronologic and geochemical evidence from sedimentary formations of the west Central Philippines
Published in Australian Journal of Earth Sciences, 2018
C. B. Dimalanta, D. V. Faustino-Eslava, J. T. Padrones, K. L. Queaño, R. A. B. Concepcion, S. Suzuki, G. P. Yumul
To minimise the uncertainties in using major oxides, elemental and binary ratio diagrams that involve immobile elements such as La, Th, Zr, Y, Hf and Co are widely used to constrain the provenance and tectonic setting of sedimentary rocks. Hayashi et al. (1997) plotted the TiO2 and Zr contents of igneous rocks from the Abitibi greenstone belt. Results show that TiO2/Zr decreases as the SiO2 content increases. The TiO2/Zr ratios are >∼200 for mafic igneous rocks, 55–195 for intermediate igneous rocks and <55 for felsic igneous rocks. From this relationship, the TiO2vs Zr diagram was constructed and used as a provenance diagram (Hayashi et al., 1997). The majority of the samples from Palawan, northwest Mindoro and northwest Panay occupy the felsic igneous rock field with a few samples plotting in the intermediate igneous rock provenance field (Figure 6b).