Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8908591 | Tectonophysics | 2018 | 83 Pages |
Abstract
In this study, we report new microfabrics, pressure-temperature estimates and 40Ar/39Ar ages from high-pressure (HP) rocks of southeastern Naxos in Cyclades, Aegean Sea. Most metapelitic rocks contain two generations of white mica, high-Si phengites crystallized during HP metamorphism and low-Si white mica formed during subsequent retrogressive overprint. 40Ar/39Ar white mica dating of five white mica samples yielded ages of ca. 51-40â¯Ma, with a mean at 45â¯Ma for the peak pressure conditions and ca. 35-29â¯Ma for the retrogressive greenschist-facies overprint, as well as ca. 16â¯Ma for the strongly sheared rocks. Even though the overprint at the greenschist-facies conditions is at ca. 350â¯Â°C and 5â¯kbar, the phengite ages show that the white mica still records the age of the HP metamorphism. This implies that further factors such as deformed microstructure processes and fluid flow along with temperature-controlled diffusion contributed to Ar loss. The age and conditions of this first stage of greenschist-facies overprint at 35-29â¯Ma are similar over a large area of the southern Aegean Sea. This event represents an exhumation event, when the continental Adriatic microplate entered the subduction zone. The greenschist-facies marked a thermal pulse during exhumation. Stacking of passive margin cover successions of the subducted continental crust in a caterpillar-like mode would have triggered this, as previously suggested by modelling work.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Earth-Surface Processes
Authors
Shuyun Cao, Franz Neubauer, Manfred Bernroider, Johann Genser,