Ion probe dating is used to determine the relative ages of amphibolite-facies meta-clastic sedimentary rocks and crosscutting granitoid rocks within an important 'basement' outcrop in northwestern Turkey. U-Pb ages of 89 detrital zircon grains separated from sillimanite-garnet micaschist from the Central Sakarya basement terrane range from 551 Ma (Ediacaran) to 2738 Ma (Neoarchean). Eighty fi ve percent of the ages are 90-110% concordant. Zircon populations cluster at ~550-750 Ma (28 grains), ~950-1050 Ma (27 grains) and ~2000 Ma (5 grains), with smaller groupings at ~800 Ma and ~1850 Ma. Th e fi rst, prominent, population (late Neoproterozoic) refl ects derivation from a source area related to a Cadomian-Avalonian magmatic arc, or the East African orogen. An alternative Baltica-related origin is unlikely because Baltica was magmatically inactive during much of this period. Th e early Neoproterozoic ages (0.9-1.0 Ga) deviate signifi cantly from the known age spectra of Cadomian terranes and are instead consistent with derivation from northeast Africa. Th e detrital zircon age spectrum of the Sakarya basement is similar to that of Cambrian-Ordovician sandstones along the northern periphery of the Arabian-Nubian Shield (Elat sandstones). A sample of crosscutting pink alkali feldspar-rich granitoid yielded an age of 324.3±1.5 Ma, whilst a grey, well-foliated biotite granitoid was dated at 327.2±1.9 Ma. A granitoid body with biotite and amphibole yielded an age of 319.5±1.1 Ma. Th e granitoid magmatism could thus have persisted for ~8 Ma during late Early Carboniferous time, possibly related to subduction or collision of a Central Sakarya terrane with the Eurasian margin. Th e Central Sakarya terrane is likely to have rift ed during the Early Palaeozoic; i.e. relatively early compared to other Eastern Mediterranean, inferred 'Minoan terranes' and then accreted to the Eurasian margin, probably during Late Palaeozoic time. Th e diff erences in detrital zircon populations suggest that the Central Sakarya terrane was not part of the source area of Lower Carboniferous clastic sediments of the now-adjacent İstanbul terrane, consistent with these two tectonic units being far apart during Late Palaeozoic-Early Mesozoic time.