Paleomagnetic studies of Hercynian dyke provinces in the Western Mediterranean: Quantification and tectonic implications of crustal block rotations

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The pathways of magma ascent through the crust are dominated by the orientation of pre-existing and/or syn-magmatically developed faults and fractures such that the careful analysis of the spatial distribution, geometry and orientation of dyke patterns allows the reconstruction of the tectonic strain field during and after dyke emplacement. In addition, sophisticated geochronolocial methods allow a very precise age estimation of the products of dyke magmatism. Therefore, dyke swarms can be used as both age and large-scale strain markers.In the central and western Mediterranean, dyke swarms, mainly of Early Permian age, are developed in the southern Hercynian belt of Europe, such as the Catalan Coastal Ranges (CCR), Sardinia, Corsica and Sila Grande in southern Italy. Despite their similar radiometric ages and petrological similarities, the dykes are variably oriented. The proposed tectonic evolution of the dyke patterns in in the above mentioned areas is probably related to the dismemberment of the southern Hercynian belt in the central Mediterranean. Thus, the dyke provinces here can be used for gaining new insights in the detailed tectonic history of the area.Previous paleomagnetic studies on three dyke provinces on Sardinia suggest the breakup of the island in at least three parts and rotations of those parts about vertical axes relative to each other. Ongoing paleomagnetic measurements on samples from the dyke province in the Catalan Coastal Ranges add to this picture. These measurements are embedded in an interdisciplinary study involving measurements of anisotropy of magnetic susceptibiliy (AMS) and Ar/Ar dating.The submitted project aims at incorporating paleomagnetic data from the Sila Grande dyke province in order to better understand the interactions of crustal thinning towards the end of the Hercynian orogeny and the onset of transtension in the southern Hercynian belt.