Interactions between plutonism and detachments during metamorphic core complex formation, Serifos Island (Cyclades, Greece)

Abstract

In order to better understand the interactions between plutonic activity and strain localization during metamorphic core complex formation, the Miocene granodioritic pluton of Serifos (Cyclades, Greece) is studied. This pluton (11.6-9.5 Ma) intruded the Cycladic Blueschists during thinning of the Aegean domain along a system of low-angle normal faults belonging to the south dipping West Cycladic Detachment System (WCDS). Based on structural fieldwork, together with microstructural observations and anisotropy of magnetic susceptibility, we recognize a continuum of deformation from magmatic to brittle conditions within the magmatic body. This succession of deformation events is kinematically compatible with the development of the WCDS. The architecture of the pluton shows a marked asymmetry resulting from its interaction with the detachments. We propose a tectonic scenario for the emplacement of Serifos pluton and its subsequent cooling during the Aegean extension: (1) A first stage corresponds to the metamorphic core complex initiation and associated southwestward shearing along the Meghàlo Livadhi detachment. (2) In the second stage, the Serifos pluton has intruded the dome at shallow crustal level, piercing through the ductile/brittle Meghàlo Livadhi detachment. Southwest directed extensional deformation was contemporaneously transferred upward in the crust along the more localized Kàvos Kiklopas detachment. (3) The third stage was marked by synmagmatic extensional deformation and strain localization at the contact between the pluton and the host rocks resulting in nucleation of narrow shear zones, which (4) continued to develop after the pluton solidification.

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).…”

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

“…Migmatites associated with S-type granites have also been described in the cores of these metamorphic domes [Jansen and Schuiling, 1976;Lister et al, 1984;Okay and Satır, 2000b;Vanderhaeghe, 2004;Bozkurt et al, 2010;Kruckenberg et al, 2011;Laurent et al, 2015;Beaudoin et al, 2015]. These intrusions are exposed in the footwall of major detachments where they show strong foliation with extensional kinematic indicators as well as cataclastic zones at the contact with the detachments [Faure and Bonneau, 1988;Gessner et al, 2001a;Iglseder et al, 2009;Denèle et al, 2011;Rabillard et al, 2015]. They were emplaced first in the northeastern Menderes massif with the Egrigöz and Koyunoba plutons both dated at ~21 Ma (UPb crystallization ages on zircon) in the footwall of the Simav detachment [Ring and Collins, 2005].…”

“…At the same time, numerous syn-tectonic intrusive bodies were emplaced in the footwalls of detachment systems in the central Menderes massif and the Cyclades [Faure and Bonneau, 1988;Gessner et al, 2001a;Iglseder et al, 2009;Lecomte et al, 2010;Denèle et al, 2011;Laurent et al, 2015;Rabillard et al, 2015].…”

“…This high-K magmatism often developed during the exhumation of MCCs (figures 9 and 10). In this context, detachment systems control the exhumation and cooling of syn-tectonic intrusions that show a pervasive co-magmatic to ductilebrittle deformation controlled by the regional extensional stress regime [Faure and Bonneau, 1988;Dinter and Royden, 1993;Gessner et al, 2001a;Denèle et al, 2011;Laurent et al, 2015;Rabillard et al, 2015]. With ongoing extension, the respective proportions of crustal and mantle source…”

Synkinematic skarns and fluid drainage along detachments: The West Cycladic Detachment System on Serifos Island (Cyclades, Greece) and its related mineralization

“…These rocks are exhumed in footwalls of MCCs (Lister et al, 1984;Buick, 1991;Urai et al, 1990;Gautier and Brun, 1994;Jolivet et al, 1994;Kumerics et al, 2005;. At around 17 Ma, the southward migrating volcanic arc reached the Cyclades, yielding syn-tectonic igneous intrusion on the islands of Tinos, Delos, Mykonos, Ikaria, Serifos and Naxos (Alther et al, 1982;Faure et al, 1991;Tschegg andGrasemann, 2009, Bolhar et al, 2010;Rabillard et al, 2015;Laurent et al, 2015;.…”