Source and evolution of ore-forming hydrothermal fluids in the northern Iberian Pyrite Belt massive sulphide deposits (SW Spain): evidence from fluid inclusions and stable isotopes

Sánchez-España, J., Velasco, F., Boyce, A.J. and Fallick, A.E. (2003) Source and evolution of ore-forming hydrothermal fluids in the northern Iberian Pyrite Belt massive sulphide deposits (SW Spain): evidence from fluid inclusions and stable isotopes. Mineralium Deposita, 38(5), pp. 519-537. (doi: 10.1007/s00126-002-0326-z)

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Publisher's URL: http://dx.doi.org/10.1007/s00126-002-0326-z

Abstract

A fluid inclusion and stable isotopic study has been undertaken on some massive sulphide deposits (Aguas Teñidas Este, Concepción, San Miguel, San Telmo and Cueva de la Mora) located in the northern Iberian Pyrite Belt. The isotopic analyses were mainly performed on quartz, chlorite, carbonate and whole rock samples from the stockworks and altered footwall zones of the deposits, and also on some fluid inclusion waters. Homogenization temperatures of fluid inclusions in quartz mostly range from 120 to 280 °C. Salinity of most fluid inclusions ranges from 2 to 14 wt% NaCl equiv. A few cases with T <sub>h</sub>=80–110 °C and salinity of 16–24 wt% NaCl equiv., have been also recognized. In addition, fluid inclusions from the Soloviejo Mn–Fe-jaspers (160–190 °C and ˜6 wt% NaCl equiv.) and some Late to Post-Hercynian quartz veins (130–270 °C and ˜4 wt% NaCl equiv.) were also studied. Isotopic results indicate that fluids in equilibrium with measured quartz (d <sup>18</sup>O <sub>fluid</sub> ˜–2 to 4‰), chlorites (d <sup>18</sup>O <sub>fluid</sub> ˜8–14‰, dD <sub>fluid</sub> ˜–45 to –27‰), whole rocks (d <sup>18</sup>O <sub>fluid</sub> ˜4–7‰, dD <sub>fluid</sub> ˜–15 to –10‰), and carbonates (d <sup>18</sup>O <sub>ankerite</sub> ˜14.5–16‰, d <sup>13</sup>C <sub>fluid</sub> =–11 to –5‰) evolved isotopically during the lifetime of the hydrothermal systems, following a waxing/waning cycle at different temperatures and water/rock ratios. The results (fluid inclusions, d <sup>18</sup>O, dD and d <sup>13</sup>C values) point to a highly evolved seawater, along with a variable (but significant) contribution of other fluid reservoirs such as magmatic and/or deep metamorphic waters, as the most probable sources for the ore-forming fluids. These fluids interacted with the underlying volcanic and sedimentary rocks during convective circulation through the upper crust.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Fallick, Professor Anthony and Boyce, Professor Adrian
Authors: Sánchez-España, J., Velasco, F., Boyce, A.J., and Fallick, A.E.
Subjects:Q Science > QE Geology
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Mineralium Deposita
Publisher:Springer
ISSN:0026-4598
ISSN (Online):1432-1866

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