Extensional faulting on Tinos Island, Aegean Sea, Greece: How many detachments?

Abstract

[1] Zircon and apatite fission track (ZFT and AFT) and (U-Th)/He, 40 Ar/ 39 Ar hornblende, and U-Pb zircon ages from the granites of Tinos Island in the Aegean Sea, Greece, suggest, together with published ZFT data, that there are three extensional detachments on Tinos. The Tinos granites crosscut the Tinos detachment. Cooling of the granites was controlled by the Livadi detachment, which occurs structurally above the Tinos detachment. Our U-Pb zircon age is 14.6 ± 0.2 Ma and two 40 Ar/ 39 Ar hornblende ages are 14.4 ± 0.4 and 13.7 ± 0.4 Ma. ZFT and AFT ages go from 14.4 ± 1.2 to 12.2 ± 1.0 Ma and 12.8 ± 2.4 to 11.9 ± 2.0 Ma. (U-Th)/He ages are from 10.4 ± 0.2 to 9.9 ± 0.2 Ma (zircon) and 11.9 ± 0.5 to 10.0 ± 0.3 Ma (apatite). All ages decrease northeastward in the direction of hanging wall transport on the Livadi detachment and age-distance relationships yield a slip rate of 2.6 (+3.3 / À1.0) km Ma À1 . This rate is smaller than a published slip rate of 6.5 km Ma À1 for the Vari detachment, which is another detachment structurally above the Tinos detachment. Because of the different rates and because published ZFT ages from the footwall of the Vari detachment are $10 Ma, we propose that the Vari detachment has to be distinguished from the older Livadi detachment. We discuss various models of how the extensional detachments may have evolved and prefer a scenario in which the Vari detachment cut down into the footwall of the Livadi detachment successively exhuming deeper structural units. The thermochronologic ages demonstrate the importance of quantitative data for constraining localization processes during extensional deformation. Citation: Brichau, S

Cenozoic geodynamic evolution of the Aegean

“…Reconstructions of the internal deformation is similar to Jolivet et al (2003) and Lacombe and Jolivet (2005). The details for the Aegean region shows the main paleogeographic domains and the position and nature of the magmatic arc (Pe-Piper and Piper 2002 sense of shear (Faure et al 1991;Gautier and Brun 1994a, b;Jolivet and Patriat 1999) indicating the synkinematic nature of the intrusion during the Early Miocene (from 19 to 14 Ma) (Bröcker and Franz 1994, 2000Brichau et al 2007). Comparable timing is observed in the nearby island of Mykonos where a migmatite dome and a 10-Ma-old granodiorite were exhumed below a shallownortheast-dipping detachment (Faure and Bonneau 1988;Faure et al 1991;Gautier and Brun 1994a, b;Avigad et al 1998).…”

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, the NCDS accommodated this exhumation since the Oligocene (figures 9 and 11) [Faure et al, 1991;Lee and Lister, 1992;Brichau et al, 2007Brichau et al, , 2008Jolivet et al, 2010a] while the NPEFS and the WCDS became active in the early Miocene [Urai et al, 1990;Gautier et al, 1993;Vanderhaeghe, 2004;Brichau et al, 2006;Seward et al, 2009;Iglseder et al, 2011;Grasemann et al, 2012]. Syntectonic sediments started to be deposited in the hanging wall of these extensional structures [Photiades, 2002;Sánchez-Gómez et al, 2002;Kuhlemann et al, 2004;Lecomte et al, 2010;Laurent et al, 2015].…”

“…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…”

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

“…We applied this method to the footwalls of several prominent top-N to top-E detachments located in the northern flank of the Cyclades horst, including the islands of Tinos (Brichau et al 2007), Syros (Ring et al 2003a), Mykonos , Naxos/Paros (Brichau et al 2006), and Ikaria/Samos (Kumerics et al 2005) (Fig. 1).…”