Thermochronometric constraints on the tectonic evolution of the Serifos detachment, Aegean Sea, Greece

Abstract

We constrain the timing and kinematics of the Serifos detachment in the southwestern Cyclades, Greece, using low-temperature thermochronometry. Fission-track dating shows that the Serifos detachment was active between *13 and 6 Ma and that the Serifos granodiorite in its footwall intruded at or before *12-11 Ma into the extensional shear zone and initially cooled very rapidly at rates [180°C per million year. The mylonite zone at the top of the granodiorite and mylonitic structures in its country rocks record a consistent top-SSW shear sense in the ductile crust. In the brittle regime top-NNE shear-sense indicators occur as well. Conjugate top-SSW and top-NNE high-angle normal faults are the youngest deformational features and cut across the detachment. Age-distance relationships for the fission-track data display a relatively flat pattern. We discuss a model advocating initial top-SSW movement on the Serifos detachment before and during emplacement of the granodiorite. Updoming of the detachment during exhumation and cooling caused subsequent bivergent extension in the brittle crust.

The geological signature of a slab tear below the Aegean

“…The Western Cyclades, Kea, Kythnos and Serifos, as well as the Lavrion region, show an opposite sense of shear, top-to-the southwest, below the WCDS (Grasemann and Petrakakis, 2007;Brichau et al, 2010;Iglseder et al, 2011;Grasemann et al, 2012;Rabillard et al, 2014). A top-to-the south detachment has also been described on Ios and Sifnos (Lister et al, 1984;Vandenberg and Lister, 1996;Ring et al, 2011).…”

“…(Altherr et al, 1982;Henjes-Kunst et al, 1988;Wijbrans and McDougall, 1988;Schliestedt et al, 1994;Keay et al, 2001;Hejl et al, 2002;Parra et al, 2002;Ring et al, 2003;Bröcker et al, 2004;Jolivet et al, 2004a;Kumerics et al, 2005;Brichau et al, 2006;Bröcker and Franz, 2006;Duchêne et al, 2006;Martin et al, 2006;Brichau et al, 2007;Skarpelis et al, 2008;Baltatzis et al, 2009;Iglseder et al, 2009;Liati et al, 2009;Seward et al, 2009;Bolhar et al, 2010;Brichau et al, 2010;Denèle et al, 2011;Ring et al, 2011;Schneider et al, 2011;Grasemann et al, 2012;Bargnesi et al, 2013;Berger et al, 2013;Bröcker et al, 2013;Soukis and Stockli, 2013;Beaudoin et al, 2014;Huet et al, 2014;Laurent et al, 2015) A C C E P T E D M A N U S C R I P T…”

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…5-8.5 kbar, 500-700°C) and associated migmatites also developed in the central Cyclades, such as in the Naxos, Paros, Mykonos and Ikaria islands [Jansen and Schuiling, 1976;Lister et al, 1984;Urai et al, 1990;Keay et al, 2001;Vanderhaeghe, 2004;Duchêne et al, 2006;Kruckenberg et al, 2011;Beaudoin et al, 2015;Laurent et al, 2015]. Exhumation of these rocks as MCCs was accommodated during the Oligocene-Miocene by several ductile-brittle detachment systems (figures 4 and 6) comprising the top-to-the NE North Cycladic Detachment System (NCDS) [Faure et al, 1991;Lee and Lister, 1992;Gautier and Brun, 1994;Mehl et al, 2005Mehl et al, , 2007Brichau et al, 2007Brichau et al, , 2008Jolivet et al, 2010a], the top-to-the N Naxos/Paros Extensional Fault System (NPEFS) [Urai et al, 1990;Gautier et al, 1993;Brichau et al, 2006;Seward et al, 2009;Bargnesi et al, 2013] and the top-to-the SW West Cycladic Detachment System (WCDS) [Grasemann and Petrakakis, 2007;Brichau et al, 2010;Iglseder et al, 2011;Grasemann et al, 2012]. The minimum offset of these extensional structures is estimated at 60-100 km for the NCDS [Jolivet et al, 2004a;Brichau et al, 2008] and ~50 km for the NPEFS (figure 3) [Brichau et al, 2006].…”

“…In the Cyclades, for example, three large-scale structures with wellconstrained kinematics and timing have been considered: the NCDS cropping out in the Tinos, Mykonos and Ikaria islands [Lee and Lister, 1992;Gautier and Brun, 1994;Mehl et al, 2005;Brichau et al, 2007;Jolivet et al, 2010a;Lecomte et al, 2010], the NPEFS cropping out in the Naxos and Paros islands [Lister et al, 1984;Urai et al, 1990;Gautier et al, 1993;Seward et al, 2009;Bargnesi et al, 2013] and the WCDS cropping out in the Serifos island (figures 3 and 6) [Grasemann and Petrakakis, 2007;Brichau et al, 2010;Iglseder et al, 2011; A C C E P T E D M A N U S C R I P T…”

“…Ma ago below the WCDS (figures 9 and 11) [Brichau et al, 2006[Brichau et al, , 2008[Brichau et al, , 2010Jolivet et al, 2010a]. Surface exposure of the metamorphic rocks then occurred in the late Miocene (figure 11) [Sánchez-Gómez et al, 2002].…”