Geodynamic significance of the Santorini Detachment System (Cyclades, Greece)

Abstract

AbstractWe present field and geochronologic evidence for a Miocene top‐to‐SSE detachment system on Santorini, which exhumed the Cycladic Blueschist Unit (CBU) below a package of low‐grade Upper Triassic marbles that contain well‐preserved Megalodon fossils forming a syncline with metaflysch in the core. White mica bundles from the mylonitic foliation in the CBU yield 40Ar/39Ar dates of 25–19 Ma and zircon (U–Th)/He dates are 11–8 Ma. A weakly foliated granitic intrusion that cross‐cuts the CBU is 8.5 Ma based on zircon U–Pb geochronology. Detrital white mica from the metaflysch yields Jurassic to early Palaeogene single grain 40Ar/39Ar dates, with a dominant Palaeocene signature. Zircon (U–Th)/He dating similarly reveals dispersed ages between 36 and 15 Ma suggesting Miocene metamorphic temperatures were insufficient (<200°C) to completely reset all of the zircon cooling ages. The low‐grade rocks of the hangingwall above the newly discovered Miocene low‐angle Santorini Detachment System most likely belong to the Pelagonian zone with a Triassic carbonate platform discordantly transgressed by an Eocene flysch deposit.