Zircon U-Pb and geochemical signatures in high-pressure, low-temperature metamorphic rocks as recorders of subduction zone processes, Sikinos and Ios islands, Greece

Zircon U-Pb dating is a powerful and widely used geochronologic technique to constrain the timing rates of magmatic high lower-grade metamorphic processes, as well sediment provenance. trace element (TE) compositions also record processes during zircon growth. In this study, laser ablation split-stream (LA-SS)-ICP-MS TE depth-profiling novel two-dimensional mapping techniques are in combination with oxygen isotope analyses (secondary ion mass spectrometry, SIMS) reconstruct conditions recorded by recrystallization growth rims, which provide valuable insight into petro-tectonic evolution high-pressure/low-temperature (HP/LT) rocks formed subduction zones. These applied grains from HP/LT Cycladic Blueschist Unit (CBU) Basement (CB) on Sikinos Ios islands, Greece, experienced metamorphism deformation associated subsequent back-arc exhumation. records multiple episodes non-magmatic rim at ~50 Ma ~ 26 Ma. Eocene rims observed both units, suggesting likely juxtaposition prior or HP metamorphism. The similarity between concentrations ?18O values their corresponding cores an indicator for re-crystallization precipitation mechanism contrast, Oligocene appear be restricted < 0.5 km thick zone along CB-CBU contact, characterized garnet break-down, show HREE enrichment higher ?18O compared cores, consistent model metasomatic infiltration fluids derived dehydrating sedimentary progressive underplating extension. This appears static nature does not support major late Cenozoic reactivation contact extensional shear