The School of Geography, Earth and Environmental Sciences organises a regular series of research seminars throughout the academic year to which everyone is welcome to attend. Speakers - both external and internal to the University - will talk on topics related to all aspects of Earth Sciences.
Today's speaker is Dr Philippe Boulvais from the University of Rennes.
The South Armorican Shear Zone (SASZ) in the Armorican Massif (France) is a lithospheric-scale shear zone that was active during Variscan times. U/Pb analyses on zircon and monazite and 40Ar/39Ar analyses on muscovite from mylonites and syntectonic granites define a minimum duration of 20 Ma for the deformation and magmato-hydrothermal history along the SASZ (320 - 300 Ma).
Giant quartz veins associated with the deformed zones record important crustal-scale fluid circulations, with the contribution of both metamorphic and meteoric fluids. The heat source necessary for crustal-scale downward fluid infiltration and upward motion was likely provided by the exhumation of lower crustal units in the South Armorican domain. Various ore deposits, notably uranium ores, were formed in this context. Therefore, this integrated study that combines geometry, oxygen isotope, Ar/Ar and U/Pb geochronology helps to draw a metallogenic crustal landscape for the region.