Ductile nappe stacking and refolding in the Cycladic Blueschist Unit: insights from Sifnos Island (south Aegean Sea)

Abstract

post-orogenic extension. Our new kinematic results in combination with previous works in the Cyclades area reveal a regional scale change in tectonic transport direction from (W)NW-(E)SE at Late Cretaceous-middle Eocene to (E) NE-(W)SW at late Eocene-Oligocene times. The observed change in transport direction may be governed by the relative motion of Africa with respect to Europe during Alpine orogeny.

Exhumation of eclogite and blueschist (Cyclades, Greece): Pressure–temperature evolution determined by thermobarometry and garnet equilibrium modelling

“…For example, Philippon et al. () identified on Syros prograde top‐to‐the SW sense of shear affecting pseudomorphs of lawsonite, while kilometric SW verging folds have been interpreted as prograde drag folds on Sifnos (Roche et al., ; see also Aravadinou, Xypolias, Chatzaras, Iliopoulos, & Gerogiannis, , for the early top‐to‐the south component of the burial path).…”

Retroward extrusion of high‐pressure rocks: An example from the Hellenides (Pelion Blueschist Nappe, NW Aegean)

“…In this interpretation, the HP‐units of the Internal Hellenides are laterally equivalent to the external units (Figure a,bI) and have been exhumed in the footwall of syn‐ and/or post‐orogenic extensional detachments. However, several studies have shown that the exhumation of the internal HP‐units is related to NE‐directed thrusting (Figure bII) (Aravadinou, Xypolias, Chatzaras, Iliopoulos, & Gerogiannis, ; Chatzaras, Xypolias, Kokkalas, & Koukouvelas, ; Doutsos, Pe‐Piper, Boronkay, & Koukouvelas, ; Xypolias, Kokkalas, & Skourlis, ). To shed light on this controversy, we present new structural data from the Pelion Peninsula, a key area in the Internal Hellenides, where the entire sequence of a HP‐nappe as well as its bounding shear zones are clearly exposed over a confined area (Figure a).…”

The Tectonostratigraphy of Cycladic Blueschist Unit on Sikinos and Sifnos: Implication for the Mesozoic Tectonic Setting

“…4A, B), the Marble subunit is overlain by the MVS subunit. This contact is characterized by mylonitized eclogites and glaucophanites revealing that the juxtaposition of these subunits attributed to a ductile thrust that was active during the subduction stage (Aravadinou et al, 2016). In Psarobitima this subduction-related thrust brings ca.…”

“…The peak of Eocene HP-metamorphism has been estimated at 450°-550°C and 12-20 kbar while the P-T conditions of Oligo-Miocene greenschist-facies retrogression have been estimated at 350°-450°C and 6-9 kbar (e.g., Schmadicke and Will, 2003). In terms of deformation history, three phases of ductile deformation have been distinguished (D1-D3) (Lister and Raouzaios, 1996;Aravadinou et al, 2016). The D1 phase is sparse and characterized by an S1 foliation, which is presented as internal foliation in garnets or recognized where it wraps around the hinges of isoclinal, intrafolial folds.…”

“…1) is characterized by a complex deformation history, which is expressed by successive generations of ductile structures developed during the Eocene subduction and the subsequent Oligocene-Miocene exhumation of the unit. Subduction-related deformation is mainly manifested by ductile thrusting that led to the formation of individual nappe stacks within the CBU (e.g, Aravadinou et al, 2016). Ductile deformation during the exhumation is represented by thrust-sense shear zones (Xypolias et al, 2012), kilometre-scale folds (e.g., Xypolias and Alsop, 2014) and large-scale extensional detachments (Jolivet and Brun, 2010).…”