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Isotopic evidence for the origin of an acid sulphate alteration, Styrian basin, Austria
Author(s) -
Bojar AnaVoica,
Halas Stanislaw,
Bojar HansPeter,
Szaran Janina
Publication year - 2008
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.2007.00785.x
Subject(s) - alunite , geology , geochemistry , pyrite , hydrothermal circulation , volcano , biotite , mineral , sulfur , δ34s , anhydrite , volcanic ash , mineralogy , gypsum , paleontology , quartz , fluid inclusions , chemistry , organic chemistry
The Gossendorf volcanic body is the only one in the Styrian basin that shows extensive hydrothermal alteration. K‐Ar dating of primary volcanic biotite and alteration products (alunite) suggests that the emplacement of the volcanic body and hydrothermal alteration took place synchronously, 15 Ma ago. The stable isotope compositions of the alteration products such as opal, barite, pyrite and alunite combined with crystallographia investigations indicate temperatures between 150 and 200 °C for the formation of the alteration zones. The calculated stable isotopic compositions of the parent fluid, responsible for the alteration, show an exogene marine component, which interacted with the host rock. Sulphur isotopic compositions of sulphur, sulphides and sulphates indicate disequilibrium, and progressive oxidation. This fact, combined with the mineral zonation of the alteration zone, reflects not only change in the pH but also change in the f O 2 of the ascending fluids.