Zircon U-Pb geochronology of paragneisses and biotite granites from the SW Iberian Massif (Portugal): evidence for a paleogeographic link between the Ossa-Morena Ediacaran basins and the West African craton

Sensitive high-resolution ion microprobe U–Th–Pb age determinations on detrital and inherited zircon from the E ´ vora Massif (SW Iberian Massif, Portugal) provide direct evidence for the provenance of the Ossa–Morena Ediacaran basins (Se´rie Negra) and a palaeogeographical link with the West African craton. Three samples of the Se´rie Negra paragneisses contain large components of Cryogenian and Ediacaran ( zircon of Mesoproterozoic ( ( Arraiolos biotite granite, which was formed by partial melting of the Se´rie Negra and overlying Cambrian rocks. These results are consistent with substantial denudation of a continental region that supplied sediments to the Ediacaran Ossa–Morena basins during the final stages of the Cadomian–Avalonian orogeny (peri-Gondwanan margin with principal zircon-forming events at same age from Portugal, Spain, Germany and Algeria, our data suggest that the sediment supply to the Ediacaran–Early Palaeozoic siliciclastic sequences preserved in all these peri- Gondwanan regions was similar. The lack of Grenvillian-aged ( Ossa–Morena and Saxo-Thuringia Ediacaran sediments suggests that the sediment in these peri-Gondwanan basins was derived from the West African craton.c. 700–540 Ma) detrital zircon, but have a marked lack ofc. 1.8–0.9 Ga) age. Older inherited zircons are of Palaeoproterozoicc. 2.4–1.8 Ga) and Archaean (c. 3.5–2.5 Ga) age. The same age pattern is also found in thec. 575 Ma and c. 615 Ma). Combined with the detrital zircon ages reported for rocks of thec. 1.1–0.9 Ga) zircon in the