Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/16887
Title: In situ thermochemical sulfate reduction during ore formation at the Itxaspe Zn-(Pb) MVT occurrence (Basque Cantabrian Basin, Northern Spain)
Author: Piqué i Vericat, Àngels
Canals i Sabaté, Àngels
Disnar, J. R.
Grandia i Borràs, Fidel
Keywords: Geoquímica
Conques sedimentàries
Serralada Cantàbrica
Geochemistry
Sedimentary basins
Cantabrian Mountains (Spain)
Issue Date: 2009
Publisher: Universitat de Barcelona (UB). Institut de Ciències de la Terra Jaume Almera (ICTJA). Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDEA). Universitat Autonònoma de Barcelona (UAB). Consejo Superior de Investigaciones Científicas (CSIC)
Abstract: Organic matter is thought to play a role in the genesis of many Mississippi Valley-type (MVT) deposits, actino as a reducing agent during thermochemical sulfate reduction (TSR). Although TSR is an extremely slow reaction t low temperatures (lt;100ºC), under favorable conditions it may supply the necessary reduced sulfur during ore formation. To test this hypothesis, the Itxaspe Zn-(Pb) MVT occurrence in the Basque-Cantabrian basin (Northern Spain) was studied. Sphalerite, the main ore phase, is generally found disseminated in Urgonian (Lower Cretaceous) carbonates, and in close relationship with solid bitumen. The bitumen source rock was very likely deposited in a marine marginal setting. Differences in composition of the bitumen samples are attributed to a fractionation during hydrocarbon expulsion and/or migration. The fluids involved in ore deposition were low temperature (Th ~130ºC), Na-Ca-Cl-(K-Mg)-type brines (salinities ~12.5 equiv. mass % NaCl). The origin of brine solutes (including sulfate) is related to the dissolution of Mesozoic evaporite units, although the contribution of evaporated seawater brines cannot be ruled out. The temperatures of ore deposition, the close relationship between the bitumen and ore phases, the presence of aromatic sulfur-bearing compounds and the d34S of sulfides and sulfates are consistent with an in situ TSR during ore formation in the Itxaspe Zn-(Pb) occurrence. Therefore, at least for small mineralizations like Itxaspe, our conclusion is that the necessary reduced sulfur can be supplied by TSR during ore genesis at the site of metal deposition.
Note: Reproducció del document publicat a http://dx.doi.org/10.1344/105.000001448
It is part of: Geologica Acta, 2009, vol. 7, núm. 4, p. 431-449
Related resource: http://dx.doi.org/10.1344/105.000001448
URI: http://hdl.handle.net/2445/16887
ISSN: 1695-6133
Appears in Collections:Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

Files in This Item:
File Description SizeFormat 
565081.pdf3.68 MBAdobe PDFView/Open


This item is licensed under a Creative Commons License Creative Commons