Abstract

The Collserola Range includes a representative stratigraphic succession of the Palaeozoic of the central part of the Catalan Coastal Ranges, ranging from Cambro-Ordovician to Carboniferous times. In this paper we present an up-to-date review of the stratigraphy and structure of the Palaeozoic of the Collserola Range, and provide geochemical and Sm–Nd isotope data to constrain the pre-Mesozoic crustal evolution of this sector of the Variscan Belt. Geochemical compositions indicate that the Palaeozoic siliciclastic rocks of the Collserola Range were fed by a relatively mature heterogeneous source of sediment, comprising quartz-rich sediments to intermediate igneous rocks. The siliciclastic rocks of the Collserola Range show great geochemical affinity with the turbidites of passive margins. The Sm–Nd signature of the siliciclastic rocks is compatible with those of the Palaeozoic and late Proterozoic fine-grained siliciclastic rocks of the neighbouring terrains of SW Europe. There is a small decrease of the εNdT with decreasing age of sedimentation from the Cambro-Ordovician to the Carboniferous, suggesting an increase of the amount of more ‘juvenile’ material. The presence of small volumes of alkaline basaltic rocks provides evidence for the input of juvenile material in the early Palaeozoic basin and suggests that an extensional tectonic regime prevailed during the Cambro-Ordovician sedimentation. From a geodynamic point of view, the overall analysis of the data implies that the Palaeozoic rocks of the Catalan Coastal Ranges were part of the Northern Gondwana passive margin before the closure of the Rheic Ocean and the subsequent Variscan Orogeny.

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