U–Pb detrital zircon analysis of the lower allochthon of NW Iberia: age constraints, provenance and links with the Variscan mobile belt and Gondwanan cratons

Detrital U–Pb laser ablation inductively coupled plasma mass spectrometry zircon ages from six\udsiliciclastic samples from the lower allochthon of NW Iberia are analysed to constrain their maximum sedimentation\udage and provenance, and to evaluate the connections to the adjacent tectonostratigraphic domains.\udDeposited in the external sections of the Gondwana platform, their maximum depositional age is latest Neoproterozoic\ud(c. 560 Ma). Comparison of the age populations of the lower allochthon with those of the rest of\udthe allochthonous and autochthonous units of NW Iberia suggests that the terranes located in the footwall of\udthe Variscan suture should not be considered as exotic elements, but as contiguous pieces of the same continental\udmargin transported onto the adjacent Gondwana mainland in Variscan times. The data are in agreement\udwith the regional trend defined by the drop in Early Neoproterozoic and Mesoproterozoic zircon content\udupward in the tectonic pile, which had been previously proposed as a marker of proximity to the eastern part\udof the West African Craton. Based on the age spectra, the palaeoposition for the time of sedimentation is\udplaced in northern Africa, between the West African and Saharan cratons. Particular attention is paid to the\udoccurrence of an Early Neoproterozoic input, probably derived from the Pan-African Hoggar sutur