Detrital zircon U-Pb data from the Hellenic south Aegean belts: Constraints on the age and source of the South Aegean basement

Abstract

U-Pb analyses of 595 zircons from 10 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 on Milos and Santorini 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 fromca.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 fromca.202 to 3487 Ma. 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 or207Pb/206Pb) of distinct populations of 534 concordant zircons are about 316, 639, 994, 1954, 2598 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 or other parts of Gondwana.