The W-Mo deposit of Perda Majori (SE Sardinia, Italy): a fluid inclusion study of ore and gangue minerals

The W-Mo deposit of Perda Majori (SE Sardinia) consists of a NW-SE trending quartz vein that crops out for about 500 m in the Salto di Quirra region. Hercynian low-grade metamorphic rocks, which host the orebody, largely dominate the geology of the area and are themselves intruded and contact metamorphosed by late Hercynian leucogranites and leucogranite porphyries. Field evidence supports a genetic link between the orebody and the emplacement of the leucogranites. The ore paragenesis consists chiefly of wolframite, molybdenite, scheelite, pyrite and calcopyrite, while the gangue is formed of quartz, K-feldspar, albite, topaz, micas, fluorite and calcite. The highest Th (320-420-degrees-C) were found in coarse-grained quartz (Qz I) which also records signs of boiling. Inclusions found in wolframite, giving Th 310-330-degrees-C and the highest recorded salinities (6-7 wt.% NaCl eq.), suggest that ore deposition closely followed the boiling