Hydrothermal alteration of felsic volcanic rocks associated with massive sulphide deposition in the northern Iberian Pyrite Belt (SW Spain) |
| |
| Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, PR China;2. Geological Publishing House, Beijing 100083, PR China;3. Development and Research Center of China Geological Survey, Beijing 100037, PR China;4. Nonferrous Metals Geological Exploration Bureau of East China in Jiangsu Province, Nanjing 210007, China;1. Departamento de Geodinámica, Universidad de Granada, 18002 Granada, Spain;2. School of Geosciences, University of Edinburgh, The King''s Building, James Hutton Road, EH9 3FE Edinburgh, UK;3. School of Earth and Planetary Science, John de Laeter Center, Curtin University, Bentley 6845, Australia;4. Departamento de Mineralogía y Petrología, Universidad de Granada, 18002 Granada, Spain;5. Departamento de Geología, Universidad de Jaén, Jaén, Spain;6. Departamento de Física de la Materia Condensada, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Valladolid, C/ Paseo de Belén, 7, 47011 Valladolid, Spain;7. Departamento de Geodinamica, Estratigrafía y Paleontología, Universidad Complutense de Madrid, Madrid, Spain;1. Institut für Geowissenschaften, Goethe-Universität, Altenhöferallee 1, 60438 Frankfurt am Main, Germany;2. Mineralogia eta Petrologia Saila, Euskal Herriko Unibertsitatea UPV/EHU, PO Box 644, 48080 Bilbao, Spain;3. Geokronologia eta Geokimika Isotopikoaren Zerbitzua – SGIker-IBERCRON, Euskal Herriko Unibertsitatea UPV/EHU, PO Box 644, 48080 Bilbao, Spain;4. Geodinamika Saila, Euskal Herriko Unibertsitatea UPV/EHU, PO Box 644, 48080 Bilbao, Spain |
| |
| Abstract: | Massive sulphide deposits of the northern Iberian Pyrite Belt (IPB) are mainly hosted by felsic volcanic rocks of rhyolitic to dacitic composition. Beneath most of the massive ores of this area (e.g., Concepción, San Miguel, Aguas Teñidas Este or San Telmo deposits) there is usually a wide hydrothermal alteration halo associated with stockwork-type mineralization. Within these alteration envelopes there are two principal rock types: (1) chlorite-rich rocks, linked to the inner and more intensely altered zones and dominantly comprising chlorite+pyrite+quartz+sericite (+carbonate+rutile+zircon+chalcopyrite), and (2) sericite-rich rocks, more common in the peripheral zones and showing a dominant paragenesis of sericite+quartz+pyrite+chlorite (+carbonate+rutile+zircon+sphalerite). Mass-balance calculations comparing altered and least-altered felsic volcanic rocks suggest that sericitization was accompanied by moderate enrichment in Mg, Fe and H2O, with depletion in Si, Na and K, and a slight net mass loss of about 3%. Chloritization shows an overall pattern which is similar to that of the sericitic alteration, but with large gains in Fe, Mg and H2O (and minor enrichment in Si, S and Mn), and a significant loss of Na and K and a minor loss of Ca and Rb. However, chloritization has involved a much larger net mass change (mass gain of about 28%). Only a few elements such as Nb, Y, Zr, Ti, P and LREE appear to have remained inert during hydrothermal alteration, whilst Ti and Al have undergone very minor mobilization. The results point to the severity of the physico-chemical conditions that prevailed during the waxing stage of the ore-forming hydrothermal systems. Further, mineralogical and geochemical studies of the altered footwall rocks in the studied deposits indicate that hydrothermal ore-bearing fluids reacted with host rocks in a multi-stage process which produced a succession of mineralogical and chemical changes as the temperature increased. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
