DETRITAL ZIRCON U-PB AND HF ISOTOPIC DATA FROM THE HELLENIC FOREARC AND VOLCANIC ARC AREAS (ATTIKI, PELOPONNESE, KYTHERA, CRETE, MILOS, SANTORINI)

U-Pb analyses of 795 zircons from 17 metasedimentary 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 all give pre-Cenozoic U-Pb crystallization ages. Metamorphic rocks exposed within the volcanic arc and nearby the backarc on Milos, Santorini, and Attiki (Lavrio, Sounio, Penteli, Moni Asteriou, Varnavas) also lack zircons grown during the recent phase of Hellenic subduction. Samples of clastic sedimentary rocks that were affected by the Miocene metamorphism show zircon crystallization ages that range from ca. 80 to 2937 Ma. 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. 202 to 3487 Ma. Epsilon Hf values of the zircons range mostly from –20 to 12 and give depleted mantle Lu-Hf model ages from ca. 730 to 3720 Ma. The full range of epsilon values is evident in the Neoproterozoic zircons. Zircons with Archean crystallization ages are absent in the metamorphosed detrital rocks from Crete, Kythera, Peloponnese, Milos and Santorini. This is most likely because metamorphism caused the breakdown and/or recrystallization of any ancient zircons with substantial radiation damage. Mean U-Pb ages (²⁰⁶Pb/²³⁸U or ²⁰⁷Pb/²⁰⁶Pb) of distinct populations of 673 concordant zircons are about 316, 639, 994, 1954, 2598 and 3325 Ma representing provenance from multiple tectono-thermal events such as the Triassic and Variscan igneous provinces, the PanAfrican and Grenvillian orogens, and Icartian-Eburnian province. These detrital zircon crystallization ages 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 or other parts of Gondwana. The wide range of Hf-isotopic values for 700-600 Ma zircons suggests sources in the Arabian-Nubian shield and Mozambique Belt.