Vertical axis rotations accommodated along the Mid Cycladic lineament on Paros Island in the extensional heart of the Aegean orocline Greece

OpenAlex İngilizce

The Aegean-west Anatolian orocline formed due to Neogene opposite rotations of its western and eastern limbs during opening of the Aegean back-arc basin.Stretching lineations in exhumed metamorphic complexes in this basin mimic the regional vertical-axis rotation patterns and suggest that the oppositely rotating domains are sharply bounded along a Mid-Cycladic lineament, the tectonic nature of which is enigmatic.Some have proposed this lineament to be an extensional fault accommodating orogen-parallel extension, while others have considered it to be a transform fault.The island of Paros hosts the only exposure of the E-to NE-trending lineations characterizing the NW Cyclades and the N-trending lineations of the SE Cyclades.Here, we show new paleomagnetic results from isotropic, ca.16 Ma granitoids that intruded both domains and demonstrate that the trend difference resulted from post-16 Ma ~90° clockwise and 10° counterclockwise rotation of the NW and SE blocks, respectively.We interpret the semiductile to brittle, low-angle, SE-dipping Elitas shear zone that accommodated this rotation difference to reflect the Mid-Cycladic lineament.We conclude a two-stage exhumation history for Paros that is consistent with regional Aegean reconstructions.Between ca.23 and 16 Ma, the metamorphic rocks of Paros were exhumed from amphibolite-facies to greenschist-facies conditions along a top-to-the-N detachment.The Elitas shear zone then started to exhume the northwestern, clockwiserotating domain from below the southeastern, counterclockwise rotating domain since 16 Ma.From this, we infer that the Mid-Cycladic lineament is an extensional shear zone, consistent with geometric predictions that Aegean oroclinal bending was accommodated by orogennormal and orogen-parallel extension.