1 3 Int J Earth Sci (Geol Rundsch) (2016) 105:727–745 DOI 10.1007/s00531-015-1221-z ORIGINAL PAPER Detrital zircon geochronology of the Cretaceous succession from the Iberian Atlantic Margin: palaeogeographic implications Pedro A. Dinis 1 · Jorge Dinis 1 · Colombo Tassinari 2 · Andy Carter 3 · Pedro Callapez 4 · Manuel Morais 4 Received: 22 November 2014 / Accepted: 20 June 2015 / Published online: 21 July 2015 © Springer-Verlag Berlin Heidelberg 2015 in NW Iberia and the conjugate margin (Newfoundland). The Barremian unconformity marks a sudden rise in the proportion of c. 375–275 Ma zircon ages accompanied by a decrease in the abundance of the c. 420–385 Ma and c. 1.2–0.9 Ga ages. This shift in the zircon signature, which is contemporaneous with the separation of the Galicia Bank from Flemish Cap, reflects increased denudation of Variscan crystalline rocks and a reduction in source mate- rial from NW Iberia and adjoining areas. The late Aptian unconformity, which represents the largest hiatus in the sedimentary record, is reflected by a shift in late Palaeozoic peak ages from c. 330–310 Ma (widespread in Iberia) to c. 310–290 Ma (more frequent in N Iberia). It is considered that this shift in the age spectra resulted from a westward migration of catchment areas following major uplift in northern Iberia and some transport southward from the Bay of Biscay under the influence of a well-established Atlantic circulation. Keywords Provenance · Detrital zircon geochronology · Lusitanian basin · Pangea break-up · Unconformity Introduction Break-up of Pangaea and the opening of the North Atlan- tic Ocean initiated the formation of a series of basins along what is now the eastern and western margin of the Atlan- tic Ocean. The Iberian Lusitanian basin emerged from this process, while on its North American conjugate margin, in Newfoundland, several Grand Banks basins formed, including the Jeanne d’Arc, Carson, Horseshoe and Whale basins (Fig. 1). The sedimentary fill of these basins records a history of regional basement erosion that has a compo- sition and age structure dictated by a succession of events Abstract Detrital zircon U–Pb data performed on eight Cretaceous sandstone samples (819 age isotopic results) from the Lusitanian basin (west Portugal) constrain the his- tory of uplift and palaeodrainage of western Iberia follow- ing break-up of Pangaea and opening of the North Atlantic Ocean. We examined the links between shifts in provenance and known basinwide unconformities dated to the late Ber- riasian, Barremian, late Aptian and Cenomanian–Turonian. The detrital zircon record of sedimentary rocks with wider supplying areas is relatively homogenous, being character- ized by a clear predominance of late Palaeozoic ages (c. 375–275 Ma) together with variable proportions of ages in the range c. 800–460 Ma. These two groups of ages are diagnostic of sources within the Variscan Iberian Massif. A few samples also reveal significant amounts of middle Pal- aeozoic (c. 420–385 Ma) and late Mesoproterozoic to early Neoproterozoic (c. 1.2–0.9 Ga) zircon, which are almost absent in the basement to the east of the Lusitanian basin, but are common in terranes with a Laurussia affinity found Electronic supplementary material The online version of this article (doi:10.1007/s00531-015-1221-z) contains supplementary material, which is available to authorized users. * Pedro A. Dinis pdinis@dct.uc.pt 1 IMAR - Marine and Environmental Research Centre, Department of Earth Sciences, University of Coimbra, Coimbra, Portugal 2 Instituto de Geociências, Universidade de São Paulo/CPGeo, São Paulo, Brazil 3 Department of Earth and Planetary Sciences Birkbeck, University of London, London, UK 4 Centre for Geophysics, University of Coimbra, Coimbra, Portugal