The extending Hellenide orogen in the Aegean Sea of Greece (Figure 3) exposes a number of spectacular brittle low-angle normal faults (detachments) (Lister et al. 1984; Lee & Lister 1992). On some Aegean islands, the brittle detachments are associated with underlying extensional ductile shear zones and examples of these ductile-to-brittle extensional fault systems have been reported from the Cycladic islands of Naxos (Buick 1991) and Ios (Vandenberg & Lister 1996). Another well-exposed but little known example is the Messaria extensional fault system on Ikaria Island, which has been described in some detail by Christine Kumerics (Kumerics et al. 2005). Extension was accompanied by the intrusion of three granites: the large I-type Raches granite occupying the western half of the island, the smaller S-type Karkinagrion granite, which occurs within the I-type Raches granite, and the smaller S-type Xylosirtis granite at the south coast (Figure 4). The footwall of the Messaria extensional shear zone is the Ikaria nappe, which seems to be a rather exotic nappe in the central Aegean which apparently is only exposed on Ikaria and has no counterpart on the adjacent Aegean island. The Ikaria nappe may correlate to nappes on the nearby Turkish mainland.
Figure 3. Generalized map
Generalized map of the Aegean and adjacent mainlands showing tectonometamorphic units and Hellenic subduction zone. Inset shows the location of the main map.
Figure 4. Simplified geological map of Ikaria Island
Simplified geological map of Ikaria Island. Shown are tectonic units, the Messaria and Fanari extensional detachments, the localities of structural, strain, geochronological and P-T samples, the positions of two cross sections A-A’ and B-B’ shown in Fig. 3, cross section C-C’-C’’-C’’’ shown in Fig. 12, and profiles D-D’ and E-E’ for the slip-rate calculations in Fig. 17.