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3D gravity modelling of the Aguablanca Stock, tectonic control and emplacement of a Variscan gabbronorite bearing a Ni–Cu–PGE ore, SW Iberia

Published online by Cambridge University Press:  06 March 2008

I. ROMEO ,
R. TEJERO ,
R. CAPOTE  and
R. LUNAR
I. ROMEO*
Affiliation:
Department of Geology, University of California Davis, Davis, CA 95616-8605, USA
R. TEJERO
Affiliation:
Departamento de Geodinámica, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
R. CAPOTE
Affiliation:
Departamento de Geodinámica, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
R. LUNAR
Affiliation:
Departamento de Cristalografía y Mineralogía, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
*
*Author for correspondence: [email protected]
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Abstract

The Aguablanca stock is a Variscan mafic pluton located in the Ossa-Morena zone, southern Iberian Massif, hosting an unusual Ni–Cu–PGE mineralization associated with magmatic breccia pipes which intruded its northern part. The emplacement of the Aguablanca stock and the mineralized breccia pipes are related to the activity of the Cherneca ductile shear zone, a Variscan sinistral shear zone that favoured magma ascent through the upper crust. A detailed gravity study has been carried out in order to investigate the 3D geometry of the Aguablanca intrusion and to get insights about the emplacement mechanism and tectonic controls of the mineralization. The three-dimensional gravity modelling shows that the stock has an inverted drop geometry with a feeder zone in contact with the Cherneca ductile shear zone. The inferred orientation of the feeder zone suggests that the emplacement probably took place along an open tensional crack formed within the strain field of the adjacent Cherneca ductile shear zone. The modelling of the breccia pipes hosting the Ni–Cu–PGE ore shows that they are included inside the feeder zone, thus their emplacement is probably controlled by successive opening events of this tensional crack.

Keywords

three-dimensional modelsgravityplutonsemplacementnickel oresVariscan orogeny
Type
Original Article
Information
Geological Magazine , Volume 145 , Issue 3 , May 2008 , pp. 345 - 359
Copyright
Copyright © Cambridge University Press 2008

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References

Ábalos, B., Gil Ibarguchi, I. & Eguiluz, L. 1991. Cadomian subduction/collision and Variscan transpresion the Badajoz-Córdoba Shear Belt (SW Spain). Tectonophysics 199, 51–72.CrossRefGoogle Scholar
Ayala, C., Torne, M. & Pous, J. 2003. The lithosphere–asthenosphere boundary in the western Mediterranean from 3d joint gravity and geoid modelling: tectonic inplications. Earth and Planetary Science Letters 209, 275–90.CrossRefGoogle Scholar
Bachiller, N., Galindo, C., Darbyshire, D. P. F. & Casquet, C. 1997. Geocronología Rb–Sr de los leucogranitos del complejo plutónico de Burguillos del Cerro (Badajoz). Geogaceta 21, 29–30.Google Scholar
Blakely, R. J. 1995. Potential Theory in Gravity & Magnetic Applications. Cambridge University Press, 441 pp.CrossRefGoogle Scholar
Casquet, C., Galindo, C., Darbyshire, D. P. F., Noble, S. R. & Tornos, F. 1998. Fe–U–REE mineralization at Mina Monchi, Burguillos del Cerro, SW Spain. Age and isotope (U–Pb, Rb–Sr and Sm–Nd) constrints on the evolution of the ores. GAC-MAC-APGGQ Quebec ‘98 Conference Abstract 23, A-28.Google Scholar
Casquet, C., Galindo, C., Tornos, F., Velasco, F. & Canales, A. 2001. The Aguablanca Cu–Ni ore deposit (Extremadura, Spain), a case of synorogenic orthomagmatic mineralization: age and isotope composition of magmas (Sr, Nd) and ore (S). Ore Geology Reviews 18, 237–50.CrossRefGoogle Scholar
Dallmeyer, R. D., García Casquero, J. L. & Quesada, C. 1995. Ar/Ar mineral age constraints on the emplacement of the Burgillos del Cerro Igneous Complex (Ossa-Morena Zone, SW Iberia). Boletín Geológico y Minero 106, 203–14.Google Scholar
Ebbing, J. 2004. The crustal structure of the Eastern alps from a combination of 3D gravity modelling and isostatic investigations. Tectonophysics 380, 89–104.CrossRefGoogle Scholar
Ebbing, J., Janle, P., Koulouris, J. & Milkereit, B. 2001. 3D gravity modelling of the Chicxulub impact structure. Planetary and Space Science 49, 599–609.CrossRefGoogle Scholar
Eguiluz, L., Gil Ibarguchi, J. I., Ábalos, B. & Apraiz, A. 2000. Superposed Hercynian and Cadomian orogenic cycles in the Ossa Morena Zone and related areas of the Iberian Massif. Geological Society of America Bulletin 112, 1398–1413.2.0.CO;2>CrossRefGoogle Scholar
Evans-Lamswood, D. M., Butt, D. P., Jackson, R. S., Lee, D. V., Muggridge, M. G., Wheeler, R. I. & Wilton, D. H. C. 2000. Physical controls associated with the distribution of sulphides in the Vosey's Bay Ni–Cu–Co deposit, Labrador. Economic Geology 95, 749–69.Google Scholar
Expósito, I., Simancas, J. F., González Lodeiro, F., Bea, F., Montero, P. & Salman, K. 2003. Metamorphic and deformational imprint of Cambrian–Lower Ordovician rifting in the Ossa-Morena Zone (Iberian Massif, Spain). Journal of Structural Geology 25, 2077–87.CrossRefGoogle Scholar
Forrest, M. 2003. Spanish surprise. Materials World 11-9, 32–4.Google Scholar
Galadí-Enríquez, E., Galindo-Zaldívar, J., Simancas, F. & Expósito, I. 2003. Diapiric emplacement in the upper crust of a granitic body: the La Bazana granite (SW Spain). Tectonophysics 361, 83–96.CrossRefGoogle Scholar
Galindo, C., Muñoz, M. & Casquet, C. 1991. El enjambre filoniano básico intrusivo en el Complejo plutónico Táliga-Barcarrota (Ossa-Morena, Badajoz). Geogaceta 10, 87–90.Google Scholar
Glazner, A. F., Bartley, J. M. & Carl, B. S. 1999. Oblique opening and noncoaxial emplacement of the Jurassic Independence dike swarm, California. Journal of Structural Geology 21, 1275–83.CrossRefGoogle Scholar
Grabowska, T., Bojdys, G. & Dolnicki, J. 1998. Three-dimensional density model of the earth's crust and the upper mantle for the area of Poland. Journal of Geodynamics 25, 5–24.CrossRefGoogle Scholar
Hutton, D. H. W. & Reavy, R. J. 1992. Strike-slip tectonics and granite petrogenesis. Tectonics 11 (5), 960–7.CrossRefGoogle Scholar
Kober, B. 1987. Single-zircon evaporation combined with Pb+ emitter bedding for 207Pb/206Pb-age investigations using thermal ion mass spectrometry, and implications to zirconology. Contributions to Mineralogy and Petrology 96, 63–71.CrossRefGoogle Scholar
Liñán, E. & Quesada, C. 1990. Ossa-Morena zone: rift phase (Cambrian). In Pre-Mesozoic Geology of Iberia (eds Dallmeyer, R. D. & Martínez-García, E.), pp. 259–66. Berlin-Heidelberg: Springer-Verlag.Google Scholar
Lunar, R., Ortega, L., Sierra, J., García Palomero, F., Moreno, T. & Prichard, H. 1997. Ni–Cu (PGM) mineralization associated with mafic and ultramafic rocks: the recently discovered Aguablanca ore deposit, SW Spain. In Mineral Deposits (ed. Papunen, H.), pp. 463–6. Rotterdam: Balkema.Google Scholar
Montero, P., Salman, K., Bea, F., Azor, A., Exposito, I., González Lodeiro, F., Martínez Poyatos, D. & Simancas, J. F. 2000. New data on the geochronology of the Ossa-Morena Zone, Iberian Massif. Variscan-Appalachian dynamics: The building of the Upper Paleozoic basement. Basement Tectonics 15, 136–8.Google Scholar
Munhá, J., Barriga, F. J. A. S. & Kerrich, R. 1986. High 18O ore-forming fluids in volcanic hosted base metal massive sulphide deposits: geologic 18O/16O and D/H evidence for the Iberian Pyrite Belt; Crandon, Wisconsin, and Blue Hill, Maine. Economic Geology 81, 530–52.CrossRefGoogle Scholar
Ortega, L., Lunar, R., García-Palomero, F., Moreno, T., Martín Estevez, J. R., Prichard, H. M. & Fisher, P. C. 2004. The Aguablanca Ni–Cu–PGE Deposit, Southwestern Iberia: Magmatic Ore-forming Processes and Retrograde Evolution. The Canadian Mineralogist 42, 325–35.CrossRefGoogle Scholar
Ortega, L., Moreno, T., Lunar, R., Prichard, H., Sierra, J., Bomati, O., Fisher, P. & García Palomero, F. 1999. Minerales del grupo del platino y fases asociadas en el depósito de Ni–Cu–(EGP) de Aguablanca, SO Espańa. Geogaceta 25, 155–8.Google Scholar
Ortega, L., Prichard, H., Lunar, R., García Palomero, F., Moreno, T. & Fisher, P. 2000. The Aguablanca discovery. Mining Magazine 2, 78–80.Google Scholar
Parker, R. L. 1972. The rapid calculation of potential anomalies. Geophysical Journal of the Royal Astronomical Society 42, 315–34.CrossRefGoogle Scholar
Piña, R., Gervilla, F. OrtegaL. & Lunar, R. L. & Lunar, R. 2005 a. Geochemistry and mineralogy of platinum-group elements in the Aguablanca Ni–Cu deposit (SW Spain). In Platinum-Group Elements from Genesis to Beneficiation and Enviromental Impact (eds Törmänen, T. O. & Alapieti, T. T.), pp. 215–18. Geological Survey of Finland, GTK, XX International Platinum Symposium.Google Scholar
Piña, R., Gervilla, F., Ortega, L. & Lunar, R. 2005 b. Geoquímica de elementos calcófilos en el yacimiento de Ni–Cu–EGP de Aguablanca (Badajoz). Macla 3, 157–8.Google Scholar
Piña, R., Gervilla, F., Ortega, L. & Lunar, R. 2007. Mineralogy and geochemistry of platinum-group elements in the Aguablanca Ni–Cu deposit (SW Spain). Mineralogy and Petrology, doi:10.1007/s00710-007-0195-3, in press.CrossRefGoogle Scholar
Piña, R., Lunar, R., Ortega, L., Gervilla, F., Alapieti, T. & Martínez, C. 2004. Origen de los fragmentos máficos-ultramáficos de la brecha mineralizada del yacimiento de Ni–Cu–EGP de Aguablanca (Badajoz). Macla 2, 19–20.Google Scholar
Piña, R., Lunar, R., Ortega, L., Gervilla, F., Alapieti, T. & Martínez, C. 2006. Petrology and geochemistry of mafic–ultramafic fragments from the Aguablanca (SW Spain) Ni–Cu ore breccia: implications for the genesis of the deposit. Economic Geology 101, 865–81.CrossRefGoogle Scholar
Pinto, V., Casas, A., Rivero, L. & Torné, M. 2005. 3D gravity modelling of the Triassic salt diapirs of the Cubeta Alavesa (northern Spain). Tectonophysics 405, 65–75.CrossRefGoogle Scholar
Quesada, C. 1990. Precambrian successions in SW Iberia: their relationship to Cambrian orogenic events. In The Cadomian Orogeny (eds D'Lemos, R. S., Strachan, R. A. & Topley, C. G.), pp. 353–62. Geologial Society of London, Special Publication no. 51.Google Scholar
Quesada, C. 1991. Geological constraints on the Paleozoic tectonic evolution of tectonostratigraphic terranes in Iberian Massif. Tectonophysics 185, 225–45.CrossRefGoogle Scholar
Quesada, C. 1997. Evolución geodinámica de la Zona Ossa-Morena durante el ciclo Cadomiense. In Estudo sobre a geología da Zona de Ossa-Morena (Maciço Ibérico) (eds Araujo, A. & Pereira, M. F.), pp. 205–30. Livro de Homenagem ao Prof. Francisco Gonçalves, Univ. de Évora.Google Scholar
Quesada, C. & Dallmeyer, R. D. 1994. Tectonothermal evolution of the Badajoz-Cordoba shear zone (SW Iberia): characteristics and 40Ar/39Ar mineral age constraints. Tectonophysics 231, 195–213.CrossRefGoogle Scholar
Quesada, C., Fonseca, P. E., Munha, J., Oliveira, J. T. & Ribeiro, A. 1994. The Beja-Acebuches Ophiolite (Southern Iberia Variscan fold belt): geological characterization and geodynamic significance. Boletín Geológico y Minero 105, 3–49.Google Scholar
Reavy, R. J. & Hutton, D. H. W. 1992. Structural controls on granitoid genesis in transpressional shear zones. Eos, Transactions, American Geophysical Union 73 (14), supplement, 276.Google Scholar
Ribeiro, A., Quesada, C. & Dallmeyer, R. D. 1990. Geodynamic evolution of the Iberian Massif. In Premesozoic Geology of Iberia (eds Dallmeyer, R. D. & Martínezdr García, E.), pp. 339–409. Heidelberg: Springer Verlag.Google Scholar
Romeo, I., Capote, R. & Lunar, R. 2007. Crystallographic preferred orientations and microstructure of a Variscan marble mylonite in the Ossa-Morena Zone (SW Iberia). Journal of Structural Geology 29, 1353–68.CrossRefGoogle Scholar
Romeo, I., Capote, R., Lunar, R. & Cayzer, N. 2007. Polymineralic orientation analysis of magmatic rocks using Electron Back-Scatter Diffraction: Implications for igneous fabric origin and evolution. Tectonophysics 444, 45–62.CrossRefGoogle Scholar
Romeo, I., Capote, R., Tejero, R., Lunar, R. & Quesada, C. 2006 a. Magma emplacement in transpression: the Santa Olalla Igneous Complex (Ossa-Morena Zone, SW Iberia). Journal of Structural Geology 28, 1821–34.CrossRefGoogle Scholar
Romeo, I., Lunar, R., Capote, R., Quesada, C., Dunning, G. R., Piña, R. & Ortega, L. 2004. Edades de cristalización U–Pb en circones del Complejo Ígneo de Santa Olalla de Cala: implicaciones en la edad del yacimiento de Ni–Cu–EGP de Aguablanca (Badajoz). Macla 2, 29–30.Google Scholar
Romeo, I., Lunar, R., Capote, R., Quesada, C., Dunning, G. R., Piña, R. & Ortega, L. 2006 b. U/Pb age constraints on Variscan Magmatism and Ni–Cu–PGE metallogeny in the Ossa-Morena Zone (SW Iberia). Journal of the Geological Society, London 163, 837–46.CrossRefGoogle Scholar
Santos, J. F., Mata, J., Gonçalves, F. & Munhá, J. 1987. Contribuiçăo para o conhecimento geológico-petrológico da regiăo de Santa Súzana: O complexo Vulcanosedimentar da Toca da Moura. Comunicaçoes Serviços Geológicos de Portugal 73, 29–48.Google Scholar
Sánchez-García, M. T., Bellido, F. & Quesada, C. 2003. Gedynamic setting and geochemical signatures of Cambrian–Ordovician rift-related igneous rocks (Ossa-Morena Zone, SW Iberia). Tectonophysics 365, 233–55.CrossRefGoogle Scholar
Tornos, F., Casquet, C., Galindo, C., Canales, A. & Velasco, F. 1999. The genesis of the Variscan ultramafic-hosted magmatic Cu–Ni deposit of Aguablanca, SW Spain. In Mineral Deposits: Processes to Processing (eds Stanley, C. J. et al. ), pp. 795–8. Rotterdam: Balkema.Google Scholar
Tornos, F., Casquet, C., Galindo, C., Velasco, F. & Canales, A. 2001. A new style of Ni–Cu mineralization related to magmatic breccia pipes in a transpressional magmatic arc, Aguablanca, Spain. Mineralium Deposita 36, 700–6.CrossRefGoogle Scholar
Vauchez, A. 1975. Tectoniques tangéantielles superposées dans le segment hercynien Sud-Ibérique: les nappes et plis couchés de la région d'Alconchel-Fregenal de la Sierra (Badajoz). Boletín Geológico y Minero 86, 573–80.Google Scholar
Vigneresse, J. L. 1990. Use and misuse of geophysical data to determine the shape at depth of granitic intrusions. Geological Journal 25, 249–60.CrossRefGoogle Scholar
Yegorova, T. P., Stephenson, R. A., Kostyuchenko, S. L., Baranova, E. P., Starostenko, V. I. & Popolitov, K. E. 2004. Structure of the lithosphere below the southern margin of the East European craton (Ukraine and Russia) from gravity and seismic data. Tectonophysics 381, 81–100.CrossRefGoogle Scholar
Yenes, M., Alvarez, F. & Gutiérrez-Alonso, G. 1999. Granite emplacement in orogenic compressional conditions: the La Alberca-Béjar granitic area (Spanish Central System, Variscan Iberian Belt). Journal of Structural Geology 21, 1419–40.CrossRefGoogle Scholar