A new 3D geological model and interpretation of structural evolution of the world-class Rio Tinto VMS deposit,Iberian Pyrite Belt (Spain) |
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| Affiliation: | 1. Department of Geology, Oviedo University, C/Arias de Velasco s/n, E-33005 Oviedo, Spain;2. Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, United Kingdom;3. Department of Mines Research and Exploitation, Oviedo University, E-33004 Oviedo, Spain;4. Emed-Tartessus, La Dehesa S/N, Minas de Rio Tinto, E-21.660 Huelva, Spain;1. Instituto de Ciências da Terra (ICT), DCT (ECUM) Polo da Universidade do Minho, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal;2. Centro de Investigación para la Ingeniería en Minería Sostenible, Escuela Técnica Superior de Ingeniería, Universidad de Huelva, Ctra. Palos de la Frontera, s/n, 21819 Palos de la Frontera, Huelva, Spain;1. MLR Key Laboratory of Metallogeny and Mineral Resource Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2. Centre for Exploration Targeting and Australian Research Council Centre of Excellence for Core to Crust Fluid Systems (CCFS), School of Earth and Environment, The University of Western Australia, Crawley, WA 6009, Australia;3. Centre of Studies in Resources Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India;1. General Directorate of Mineral Research and Exploration of Turkey, Department of Mineral Research and Exploration, Ankara 06520, Turkey;2. School of Earth and Environmental Sciences, Seoul National University, Seoul, Republic of Korea;3. Centre for Exploration Targeting, University of Western Australia, Australia;4. Fırat University, Department of Geology Engineering, 23119 Elazığ, Turkey;5. Department of Energy & Resources Engineering, Inha University, Incheon, Republic of Korea;6. Department of Geology, University of Maryland, College Park, MD 20742, USA;7. International School for Geoscience Resources, Korea Institute of Geoscience and Mineral Resources, Daejeon, Republic of Korea;1. Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, D.F., Mexico;2. Centro de Geociencias, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, 76230 Juriquilla, Querétaro, Mexico;3. Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), Martí i Franquès s/n, 08028 Barcelona, Catalonia, Spain;4. Departament d''Enginyeria Minera i Recursos Naturals, Universitat Politècnica de Catalunya, Av. de les Bases de Manresa 61-73, 08242 Manresa, Catalonia, Spain;5. Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, D.F., Mexico;7. Instituto Tecnológico Superior de Tacámbaro. Av. Tecnológico 201, Zona El Gigante, 61650 Tacámbaro, Michoacán, Mexico |
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| Abstract: | A new 3D geological model and interpretation of structural evolution of the Rio Tinto world-class VMS deposit are presented in this work. The Rio Tinto volcanogenic massive sulfide (VMS) deposit is located in the Spanish segment of the Iberian Pyrite Belt and is hosted by felsic porphyritic volcanic rocks and tuffs. Computer generated 3D modeling of the different orebodies and host rocks has been carried out using data from around 3000 drill-core logs, allowing us to build 93 cross-sections and 6 plants (both 50 m spacing). This has enabled us to recognize the geometry and relationships between the mineralization and the earliest Carboniferous transtensional tectonics through the development of an extensional pull-apart basin with two sub-basins separated by the NW-SE trending Eduardo Fault. The sub-basins, Cerro Colorado and San Dionisio, were limited by two E-W strike-slip faults, the Northern and Southern faults, and bounded in the east and west by the NW-SE-trending Nerva and Western faults, respectively. The generated pull-apart basin was first filled by a basaltic magmatism of mantle origin and later, following the deposition of the intermediate complex sedimentary unit, by rhyodacitic volcanic rocks of crustal origin. The evolution of the subsiding basins caused the development of an E-W oriented rollover anticline that affected these filling rocks.As a result of a counterclockwise rotation of the stress axes, the primitive pull-apart basin evolved into a basin affected by E-W transtensional sinistral shearing. Its northern and southern limits were favorable areas for increased hydrothermal fluid flow, which gave way to the huge concentration of VMS mineralization located near the limits. The Northern and, to a lesser degree, the Southern extensional faults thus become channel areas for feeding and discharging of the VMS and stockwork ores. The main mineralizing period was related to this stage. Subsequently, during the Variscan transpressional phase, the E-W extensional faults were reactivated as inverse faults, affecting the volcanic sequence of mafic to felsic composition and the intermediate complex sedimentary unit. Fault propagation folds developed above these faults, affecting the massive sulfides, the transition series and the Culm flysch sediments, with buttressing playing a significant role in the geometry of tectonically inverted structures. The VMS mineralization and cupriferous stockworks were folded and dismembered from the original conduits in the volcanic series, and a dextral reactivation of the NW-SE trending faults also developed.Finally, it should be emphasized that this new 3D geological model is an approach to provide a better insight into the 3D structure of the world-class VMS Rio Tinto deposit and could be a key-point for further studies providing a new tool to increase knowledge of the VMS mineralizations and exploration guidelines elsewhere in the IPB. |
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