Hydrothermal fluid evolution of the Sn-W mineralization in the Parilla ore deposit (Careres, Spain)

Abstract

The Parrilla orebody, located on the southern border of the Cáceres province, is a stockwork of quartz veins with scheelite and cassiterite. The Sn-W ore fills fractures in the Greywacke Schist Complex, intruded in this area by Hercynian granites. Most of the veins strike N30°E and dip 45°SE. The mineral association includes scheelite and cassiterite, which are the most important economic minerals, and arsenopyrite, wolframite, sphalerite, chalcopyrite, pyrite, bismuth sulphosalts, pyrrhotite, quartz, muscovite and tourmaline.

The study of the fluid inclusions was undertaken using quartz and scheelite belonging to the different veins. The physicochemical characteristics of the inclusions indicate three stages of fluid circulation. The first stage is characterized by aqueous and complex CO2-aqueous inclusions (<7 wt% NaCl equiv.) trapped at temperatures between 350 and 225 °C. The second stage is represented by low-salinity aqueous inclusions (<7wt% NaCl equiv.) trapped at homogenization temperatures between 225 and 150 °C. The third stage is characterized by mixed salt-aqueous inclusions (<31 wt% NaCl equiv.) trapped at homogenization temperatures between 150 and 70°C.