The Aguablanca Ni-Cu-PGE deposit, southwestern Iberia; magmatic ore-forming processes and retrograde evolution
The Aguablanca Ni-Cu-PGE deposit, southwestern Iberia; magmatic ore-forming processes and retrograde evolution (in Platinum-group elements; petrology, geochemistry, mineralogy, James E. Mungall (editor), William E. Meurer (editor) and Robert F. Martin (editor))
The Canadian Mineralogist (April 2004) 42, Part 2: 325-350
- alteration
- Andalusia Spain
- arsenides
- bismuthides
- copper ores
- Europe
- Huelva Spain
- hydrothermal alteration
- Iberian Peninsula
- magmatism
- metal ores
- metals
- metamorphism
- metasomatism
- michenerite
- mineral assemblages
- mineral deposits, genesis
- nickel ores
- oxides
- platinum group
- platinum minerals
- platinum ores
- pyrrhotite
- retrograde metamorphism
- Southern Europe
- Spain
- sperrylite
- sulfides
- tellurides
- Variscides
- merenskyite
- melonite
- moncheite
- Aguablanca Deposit
The Aguablanca Ni-Cu-PGE deposit, SW Spain, has a magmatic origin and has been reworked by later skarn-related hydrothermal activity. Base-metal sulphides are associated with igneous cumulates with sub-vertical layering of gabbro, norite and dolerite, with fragments of pyroxenite and peridotite. These rocks show a pervasive early overprint of actinolite + or - chlorite + or - epidote + or - albite + or - serpentine, followed by growth of talc + or - chlorite + or - carbonates. The base-metal sulphides are concentrated in two subvertical bodies and consist of pyrrhotite, pentlandite and chalcopyrite, overprinted by fluid-deposited pyrite. The mineralization includes: 1) disseminated ore (1 < Ni/Cu < 1.5), with sulphides interstitial to the igneous silicates, 2) semi-massive to massive ore (2 < Ni/Cu < 5) with net-textured to poikilitic sulphides, 3) breccia ore with fragments of unmineralized ultramafic rocks in a massive sulphide matrix, 4) nodules of sulphides, 5) pyrrhotite veinlets and 6) chalcopyrite veinlets.The PGE content and (Pt + Pd)/Ru + Ir + Os) ratio are highest in the Cu-rich disseminated ore and associated veinlets of chalcopyrite. The PGM minerals associated with the base-metal sulphides include michenerite, merenskyite, moncheite, melonite and sperrylite, which mostly occur enclosed in sulphides or close to contacts between them. The PGE tellurides show extensive substitutiion of Bi for Te, indicating formation temperatures < 500 degrees C. The composition of the PGM and their association with magmatic base-metal sulphides suggest that they exsolved from the sulphides during subsolidus recrystallization, though some remobilization may have occurred in areas of pervasive fluid circulation.