Metamorphosed and Metamorphogenic Ores of the Neves Corvo Volcanogenic Massive Sulfide Deposit, Iberian Pyrite Belt, Portugal

Neves Corvo the highest-grade deposit ever found on the Iberian Pyrite Belt, the richest volcanic massive sulfide (VMS) metallogenic province in the World, has been intensely studied during the last decade. In spite of research, the origin of Neves Corvo remains problematic. Based on extensive research on the characteristics of Neves Corvo fluid inclusions, I present a new interpretation for the genesis of the copper and tin ores overlying the massive sulfides, and for the stockwork copper ore. Quartz and cassiterite from these orebodies contain abundant dense aqueous carbonic fluids, the pressures of formation of which are incompatible with formation in a VMS environment. Petrographic and tectonostratigraphic evidence support a metamorphic origin. I propose that the rubané ores are metamorphogenic, and formed during orogenic recrystallization that affected the rocks about 30 m.y. after their formation; copper deposits in fissures are a stockwork ore intensely modified during the same metamorphic event.

[1]  J. T. Oliveira,et al.  Stratigraphy of the tectonically imbricated lithological succession of the Neves Corvo mine area, Iberian Pyrite Belt, Portugal , 2004 .

[2]  M. Cathelineau,et al.  Remobilisation of base metals and gold by Variscan metamorphic fluids in the south Iberian pyrite belt: evidence from the Tharsis VMS deposit , 2003 .

[3]  R. Bakker.  Package FLUIDS 1. Computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties , 2003 .

[4]  C. Soriano,et al.  Variscan tectonics in the Iberian Pyrite Belt, South Portuguese Zone , 2002 .

[5]  A. V. D. Kerkhof,et al.  Fluid inclusion petrography , 2001 .

[6]  A. Moura.  Quartz Geobarometry: insight using favourable fluid inclusions entrapped in the homogeneous P-T field , 2001 .

[7]  B. Marshall,et al.  Fluid inclusions in metamorphosed and synmetamorphic (including metamorphogenic) base and precious metal deposits: indicators of ore-forming conditions and/or ore-modifying histories , 2000 .

[8]  Nicholas H.S. Oliver,et al.  Metamorphic fluids and their relationship to the formation of Metamorphosed and Metamorphogenic Ore Deposits , 2000 .

[9]  B. Marshall,et al.  Remobilization, syn-tectonic processes and massive sulphide deposits , 1993 .

[10]  W. Pohl.  Defining metamorphogenic mineral deposits —an introduction , 1992 .

[11]  J. Munhá.  Metamorphic Evolution of the South Portuguese/Pulo Do Lobo Zone , 1990 .

[12]  Richard H. Sibson,et al.  Earthquake rupturing as a mineralizing agent in hydrothermal systems , 1987 .

[13]  B. Marshall,et al.  Textural evidence for remobilization in metamorphic environments , 1987 .

[14]  Timothy N. Lincoln.  The redistribution of copper during low-grade metamorphism of the Karmutsen Volcanics, Vancouver Island, British Columbia , 1981 .

[15]  A. Mookherjee.  'Metamorphic' and 'metamorphosed' sulfide deposits , 1970 .

[16]  F. M. Vokes.  A review of the metamorphism of sulphide deposits , 1969 .