caa a22 4500 606150161 CHVBK 20210128100537.0 cr unu---uuuuu 210128e20150301xx s 000 0 eng 10.1007/s00531-014-1087-5 doi (NATIONALLICENCE)springer-10.1007/s00531-014-1087-5 The Tertiary dike magmatism in the Southern Alps: geochronological data and geodynamic significance [Elektronische Daten] [Maria Bergomi, Stefano Zanchetta, Annalisa Tunesi] The relationships between tectonics and magmatic activity in the Alps are still debated. Despite an active subduction since the Late Cretaceous, no arc-related magmatism is recorded prior of the Middle Eocene. The emplacement of plutons along the Insubric Fault in a short time span (~34-28Ma) has been generally interpreted in terms of the slab break-off model. The Tertiary magmatism, however, is also characterized by the occurrence of widespread calcalkaline dikes not necessarily intruded along the Insubric Fault. The geochemical features of dikes vary along the Alps belt and are interpreted in terms of mantle source heterogeneity and degree of crustal contamination. U-Pb zircon dating of studied dikes indicates intrusion ages in the 42- to 34-Ma time interval. These data provide evidence for a pre-Oligocene magmatic activity that was not solely limited to the Adamello batholith. Moreover, it appears that dikes rejuvenate from SE to NW, in an opposite direction with respect to the Alpine subduction polarity. Thus, a more complex geodynamic scenario than the slab break-off model must be envisaged. The absence of arc magmatism prior to the Middle Eocene can be explained by the low-angle subduction of the Tethyan slab that confined the mantle partial melting zone away from the orogenic wedge. The onset of the Apennines subduction at 55-50Ma caused the Alpine slab to retreat. The partial melting zone progressively migrated beneath the orogenic wedge and finally reached the axial belt in the Late Eocene, when the Alpine collision was completed. Only at this stage, slab break-off occurred and promoted the intrusion of the Periadriatic plutons. Springer-Verlag Berlin Heidelberg, 2014 Tertiary Periadriatic magmatism nationallicence Southern Alps nationallicence Dikes nationallicence U-Pb zircon dating nationallicence Bergomi Maria Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 4, 20126, Milan, Italy aut Zanchetta Stefano Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 4, 20126, Milan, Italy aut Tunesi Annalisa Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 4, 20126, Milan, Italy aut International Journal of Earth Sciences Springer Berlin Heidelberg 104/2(2015-03-01), 449-473 1437-3254 104:2<449 2015 104 531 https://doi.org/10.1007/s00531-014-1087-5 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00531-014-1087-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bergomi Maria Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 4, 20126, Milan, Italy aut NATIONALLICENCE 700 1- Zanchetta Stefano Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 4, 20126, Milan, Italy aut NATIONALLICENCE 700 1- Tunesi Annalisa Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 4, 20126, Milan, Italy aut NATIONALLICENCE 773 0- International Journal of Earth Sciences Springer Berlin Heidelberg 104/2(2015-03-01), 449-473 1437-3254 104:2<449 2015 104 531