DETRITAL ZIRCON U-PB AND HF ISOTOPIC DATA FROM THE HELLENIC SOUTH AEGEAN BELTS: CONSTRAINTS ON THE SOUTH AEGEAN BASEMENT

U-Pb analyses of 316 zircons from 10 sedimentary and plutonic rocks collected from the forearc and volcanic arc in the south Aegean, Greece constrain the provenance of the widespread Phyllite-Quartzite unit (PQU) above the retreating Hellenic subduction zone in the South Aegean. Zircons from Miocene metamorphic rocks in the forearc on the islands of Peloponnese, Kythera, and Crete lack evidence for Cenozoic to Recent crystallization. Metamorphic rocks exposed within the volcanic arc on Milos and Santorini also lack zircons grown during the recent phase of Hellenic subduction. In contrast, volcanic and plutonic rocks from Sousaki (volcanic arc) and Lavrio (backarc) contain both inherited and post-Eocene zircons, which range in age from Recent to ca. 2000 Ma. Detrital samples that have been affected by the Miocene metamorphism show zircon crystallization ages that range from ca. 55 to 2551 Ma. A sandstone collected from the upper plate of the Kythera Detachment fault, which was not affected by Miocene metamorphism based on Jurassic-Cretaceous zircon fission-track data, yields detrital zircon ages that range from ca. 274 to 3487 Ma. Depleted mantle Lu-Hf ages of the zircons from this sample range from ca. 790 to 3720 Ma. The Archean zircons are absent in the metamorphosed detrital rocks from Crete, Kythera, Peloponnese, Milos and Santorini, possibly because the metamorphism recrystallized the ancient zircons with substantial radiation damage. Mean U-Pb ages (²⁰⁶Pb/²³⁸U or ²⁰⁷Pb/²⁰⁶Pb) of distinct populations of zircons from the entire 316 grains are about 317, 644, 1940, 2542, and 3325 Ma. These populations are consistent with parts of the detritus that now makes up the South Aegean basement having a source within orogenic belts of North African and Gondwana.