New data on the ophiolitic VMS deposits of Moeche (Cabo Ortegal Complex, NW Spain)

Castroviejo Bolibar, Ricardo; Tassinari, Colombo G. y Proenza, Joaquín (2006). New data on the ophiolitic VMS deposits of Moeche (Cabo Ortegal Complex, NW Spain). En: "12th Quadrennial IAGOD Symposium 2006", 21-24 Agosto 2006, Moscú.

Descripción

Título: New data on the ophiolitic VMS deposits of Moeche (Cabo Ortegal Complex, NW Spain)
Autor/es:
  • Castroviejo Bolibar, Ricardo
  • Tassinari, Colombo G.
  • Proenza, Joaquín
Tipo de Documento: Ponencia en Congreso o Jornada (Otro)
Título del Evento: 12th Quadrennial IAGOD Symposium 2006
Fechas del Evento: 21-24 Agosto 2006
Lugar del Evento: Moscú
Título del Libro: 12th Quadrennial IAGOD Symposium 2006. Understanding the genesis of ore deposits to meet the demands of the 21st century
Fecha: 2006
Materias:
Escuela: E.T.S.I. Minas (UPM) [antigua denominación]
Departamento: Ingeniería Geológica [hasta 2014]
Licencias Creative Commons: Reconocimiento - Sin obra derivada - No comercial

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Resumen

As a result of the variscan collision, several allochtonous complexes were emplaced on the Iberian margin in Devonian times, among them the Cabo Ortegal Complex comprising the Moeche ophiolitic sequence. Copper has been won from several mines (Piquitos I & II, Barqueira, Maruxa) from disseminated ores and thin massive sulphide layers in the Moeche Unit, a strongly deformed meta-volcanic sequence comprising mainly quartz-chlorite schists and mylonites, which defines the top of the ophiolite. The ores were metamorphosed and strongly deformed under brittle conditions (for pyrite), but their textures are often apparently post-deformational, due to very common solution-transfer processes; they are composed mostly of pyrite and chalcopyrite, with minor sphalerite, pyrrhotite, etc., and with traces of native gold and PGE. The geology, mineralogy, and geochemistry of the orebodies relate closely to VMS of the Cu-Zn (Cyprus) type. Fluid inclusion studies allowed an estimation of metamorphic conditions at pressures of 2/2’5 kb and T 325/350ºC. New determinations using the chlorite geothermometer yield temperatures around 320 ºC, corresponding to pressures near 2 kb according to the isochores deduced from the fluid inclusion study, although in the Barqueira mine higher temperatures, up to 350 ºC, are found, corresponding to presssures up to 2’5 kb. Pb isotopic compositions of pyrite point to a double source of Pb, i.e. a main mantle and a subordinate crustal source. The values for 87SR/86Sr in pyrite support this interpretation, but some results suggest later mobilization in an open system, corresponding to solution-transfer. Age determinations of pyrite deduced from the Pb isotope uranogenic graph, ≈ 480 Ma, do not fit with the metamorphic ages published for the Moeche Unit, and might point to the age of Pb extraction from the mantle.

Más información

ID de Registro: 10976
Identificador DC: http://oa.upm.es/10976/
Identificador OAI: oai:oa.upm.es:10976
URL Oficial: http://www.minsoc.ru/confs.php?id=22&cid=14
Depositado por: Biblioteca ETSI Minas y Energía
Depositado el: 04 Jun 2012 14:06
Ultima Modificación: 20 Abr 2016 19:10
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