Late Variscan metamorphic and magmatic evolution in the eastern Pyrenees revealed by U-Pb age zircon dating

摘要

Variscan migmatites cropping out in the eastern Pyrenees were dated together with Late Variscan plutonic rocks. Upper Proterozoic-Lower Cambrian series were migmatized during a thermal episode that occurred in the interval 320-315 Ma coeval with the main Variscan deformation event (D_1). The calc-alkaline Sant Lloren?-La Jonquera pluton and the gabbro-diorite Ceret stock were emplaced during a later thermal episode synchronous with the D2 deformation event. A tonalite located at the base of La Jonquera suite intruded into the upper crustal levels between 314 and 311 Ma. The gabbro-diorite stock was emplaced in the middle levels of the series in two magmatic pulses at 312 and 307 Ma. The thermal evolution recorded in the eastern Pyrenees can be correlated with that of neighbouring areas of NE Iberia (Pyrenees-Catalan Coastal Ranges) and SE France (Montagne Noire). The correlation suggests a NW-SE-trending zonation where the northeasternmost areas (Montagne Noire and eastern Pyrenees) would occupy relatively more internal zones of the orogen than the southwesternmost ones.