Abstract
Abstract Rb-Sr and Pb-Pb data are reported from separated minerals (amphibole, albite, calcite, epidote), altered wall rocks, and fluid inclusions trapped in quartz, from veins associated with retrogressive shear zones cutting the Néouvielle granodiorite massif in the central French Pyrenees. Alteration in the shear zones was caused by movement of hypersaline brines during deformation. Shear zones with similar kinematics occur in granodiorites and high grade gneisses throughout the northern Axial Zone of the Pyrenees, and have been attributed variously to both the Variscan and Alpine orogenies. Rb-Sr data on a syntectonic, polymineralic vein and its altered wall rock support an Alpine age for deformation and fluid flow, giving an isochron of 47 ± 8 Ma, or 48 ± 2 Ma if albite is excluded. Another vein gives a similar age for altered wall rock and albite, but chlorite and quartz-hosted fluid inclusions are out of equilibrium. Pb data plot as quasi-linear arrays on ratio plots, with no age significance. The usefulness of this latter technique is restricted by the slow rate of uranium decay in these young rocks, but in any case Pb isotopic ratios do not appear to have homogenized during vein formation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
