Die syngenetischen Fluß- und Schwerspatmineralisationen von Arlós und Villabona in Westasturien/Nordspanien

Abstract

The fluorspar deposits of Arlos and Villabona in Western Asturias/Northern Spain occur as strata-bound mineralizations mainly in early Permotriassic sediments, and in upper parts of this formation, which is unconformably overlying the Hercynian folded palaeozoic basement. The red bed-like lithofacies developes from marine carbonate sediments to deposits of continental character. Sedimentary and diagenetic features point out clearly the syngenesis of the strata-bound mineralizations. These contain besides fluorspar predominately calcite, quartz (cherts) and vestigial iron and coppersulphides. Discordant veins comprise a synsedimentary phase of mineralisation in Permian fractures (palaeochannels) and a phase of mobilization (hydatogenic rearrangement) caused by alpide germanotyp block tectonics. Syngenetic fracture deformation of certain stratigraphical horizons, which are partly mineralized, are referred to Postvariscian movements belonging to the ceasing orogenesis. Thus is further indicated, that the mineralizations are principally Permian in age; however, those in conglomerates at higher stratigraphical levels could be Lower Triassic in age. The lacking hints at plain hydrothermal activities and the close relation between mineralizations and intensified weathering, increased rearrangement and frequent changes of facies suggest an exogenic-synsedimentary origin. The distribution of fluorine in certain palaeozoic sediments and the geochemical behaviour of fluorine within sedimentary circulation support this theory.