Geodynamic evolution of the NE Gondwana margin in the area of the Pyrenees: Chronology of granitoid placements and their geochemical and structural signatures.

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The goal of the project is a model for the evolution of the (proto-) Pyrenees based on the genesis of granitoids in the context of the Variscan mountain formation in the Axial Zone of the Pyrenees. This should be integrated into the regional development of the Gondwana shelf area during the Variscan orogeny. In the context of the current discussions and reinterpretation of regional conditions during the Variscan orogeny new questions have arisen especially in the area of the Pyrenees. Thus, an application of the current models, such as magma formation exclusively in connection with subduction zones or by gravitational collapse of the orogeny is questionable (see discussion in Franke, 2014) and must be reworked and reinterpreted. More and more evidence for increased magmatic impulses is found, which supports the theory of an increased heat flux in the entire area of Gondwana's northern rim. These effects can also be found in other areas of the Variscan zone. In order to detect a possible pulsating mantle source and the associated increased heat flux in selected areas of the Variscan basement, the following main objectives are to be pursued in this project:(1) Magmatic pulses shall be identified by the evaluation of U-Th-Pb age spectra from zircons, including xenochrysts.Additionally, the age structures of the host rocks from which the original magma for the Variscan plutons was formed will be identified. (2) The identification of crustal levels of magma formation and identification of possible protoliths using a combination of REE signatures and Lu-Hf isotopes.(3) Modelling of the crustal development by creating model ages (Lu-Hf).(4) Temporal classification of the outgoing main Variscan deformation phase D2 in the Pyrenees by analysis of microstructures.(5) After interpretation of all data sets: Proof and model development of an influence of the TUZO mantle plume during the period of the Variscan orogeny in the area of the Pyrenees, respectively the Gondwana Northern margin.