A simplified geological map of Samos Island is shown in Figure 2, the nappe pile is summarised in Table 1, the Neogene basins in Table 2, the entire sequence is schematically depicted in Figure 3 and shown on two cross sections in Figure 4. The nappe stack consists of six major tectonic units, which are described in descending order:
Figure 2. Simplified geological and tectonic map of Samos Island
Map shows major rock units, thrusts and faults (with barbs and ticks on the hanging-wall sides) and representative structural attitudes of rocks. The different nappes are described in Table 1. Lower series of graben fill comprise Basal Conglomerate, Pythagorion and Hora Formations; Upper series of graben fill include Mytilini and Kokkarion Formations (see also Figs 3 and 4 and Table 2). The D1 Ampelos and Selçuk thrusts are the basal thrusts of the Ampelos and Selçuk nappes, respectively. The D2 Pythagoras thrust put the Cycladic blueschist unit on top of the Kerketas nappe (the Pythagoras thrust is named after 'Pythagoras Cave' c. 50 m above the thrust plane west of Marathokampos). The Kallithea detachment is a late-D3 low-angle normal fault. Widespread Middle and mainly Late Miocene volcanic and volcanoclastic rocks occur at the eastern and northeastern margin of the Karlovasi and Pyrgos graben. Subordinate volcanics also occur at the western side of the Mytilini basin. Numerous reverse (D4) and normal (D5) faults overprinted all earlier ductile contacts. We interpret the curved D5 high-angle normal faults to have a listric geometry.
(1) The Kallithea nappe is part of the Cycladic ophiolite nappe of the Upper unit. It consists of peridotite, basalt, Triassic-Jurassic limestone, radiolarite and sandstone (Theodoropoulos 1979). The Katavasis complex consisting of amphibolite-facies schist, marble and amphibolite forms a tectonic block in the Kallithea nappe (Ring et al. 1999a).
(2) The Selçuk nappe is the uppermost nappe of the Cycladic blueschist unit and only exposed in a few patches. It is far more extensively exposed on the westernmost Turkish mainland some 10-20 km to the east of Samos (Gessner et al. this volume). The Selçuk nappe is essentially an ophiolitic mélange and contains metagabbro, in part in primary contact with serpentinized peridotite, and mica schist.
(3) The Ampelos nappe is made up of the shelf sequence of the Cycladic blueschist unit and contains marble (with metabauxite lenses), metapelite (including conspicuous chloritoid-kyanite schist), quartzite, glaucophane-epidote schist and greenschist. Detailed work by Ring and coworkers showed that the Ampelos nappe is correlative with the Dilek nappe of adjacent western Turkey (Ring et al. 1999a, b, 2007; Gessner et al. 2001; see also Gessner et al. this volume).
(4) The Agios Nikolaos nappe at the base of the Cycladic blueschist unit is, like the Selçuk nappe, only exposed in a few outcrops at the northern coast between the church of Agios Nikolaos and Konstandinos. It forms part of the Carboniferous and pre(?)-Carboniferous basement of the Cycladic blueschist unit and consists of metagranitic gneiss, garnet-mica schist and dolomitic marble.
(5) The Kerketas nappe of the Basal unit is made up of an at least 1000 m thick succession of monotonous dolomitic marble, the base of which is not exposed (Fig. 1). The Basal unit is generally correlated with the Tripolitza unit of the External Hellenides (Godfriaux 1968).
(6) Molasse-type sediments were deposited in the Miocene and Pliocene in N-, NE- and WNW-oriented Karlovasi, Pyrgos and Mytilini graben, which are filled with fluviatile and lacustrine sediments (Table 2, Fig. 3) (note that the sediments of the Mytilini basin and its fossil content is described in more detail in Chapter 2). Above the Basal Conglomerate Formation follows the Pythagorion and Hora Formations. Both formations also laterally interfinger with each other. The sediments of the Hora Formation are thought to have formed in a deeper basin than the limestone of the Pythagorion Formation (Weidmann et al. 1984). A major angular unconformity occurs on top of the Hora Formation. Lacustrine sedimentation is succeeded by fluviatile conglomerate of the basal Mytilini Formation (Old Mill Beds sensu Weidmann et al. 1984). Weidmann (1984) showed that in some places the unconformity occurs on top of the Old Mill Beds, whereas in other places it occurs below the Old Mill Beds. This difference might indicate that the unconformity did not occur at the same time in all parts of the basin or it might indicate that the Old Mill beds are time-transgressive.
Figure 3. Idealized comparative tectonostratigraphic columns of the nappe pile on Samos Island
Ar-Ar age data of Weidmann et al. (1984) provide age constraints for sedimentary rocks in Miocene basins.