Insights from elastic thermobarometry into exhumation of high-pressure metamorphic rocks from Syros, Greece

Abstract. Retrograde metamorphic rocks provide key insights into the pressure–temperature (P–T) evolution of exhumed material, and resultant P–T constraints have direct implications for mechanical thermal conditions subduction interfaces. However, constraining retrograde has historically been challenging resulted in debate about experienced by these rocks. In this work, we combine elastic thermobarometry with oxygen isotope thermometry to quantify Cycladic Blueschist Unit (CBU), an complex exposed on Syros, Greece. We employ quartz-in-garnet quartz-in-epidote barometry constrain pressures garnet epidote growth near peak during exhumation, respectively. Oxygen quartz calcite within boudin necks was used estimate temperatures exhumation refine pressure estimates. Three distinct groups are related different events fabrics: high-pressure at ∼1.4–1.7 GPa between 500–550 ∘C, ∼1.3–1.5 400–500 a second stage ∼1.0 400 ∘C. These results consistent stages deformation inferred from field microstructural observations, recording prograde blueschist–eclogite facies subsequent retrogression under blueschist–greenschist conditions. Our new indicate that CBU cooling decompression after reaching maximum high-pressure–low-temperature structural observations channel proximity refrigerating subducting plate, prior Miocene core-complex formation. This study also illustrates potential using combination constraints, better understand P–T-deformation mineral (HP/LT) terranes.