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The Geological Structure of Cyprus

 

Cyprus is divided into four geological zones: (a) the Pentadaktylos (Kyrenia) Zone; (b) the Troodos Zone or Troodos Ophiolite; (c) the Mamonia Zone or Complex; and, (d) the Zone of the autochthonous sedimentary rocks (Fig. 1).

 

The Pentadaktylos (Kyrenia) Zone is the northern-most geological zone of Cyprus and is considered to be the southern-most portion of the Tauro-Diranide Alpine Orogenic Zone.  The base of the Zone is mostly composed of a series of allochthonous massive and recrystallised limestones, dolomites and marbles of Permian–Carboniferous to Lower Cretaceous age (between 350–135 Ma).  These are stratigraphically followed by younger autochthonous sedimentary rocks of Upper Cretaceous to Middle Miocene age (67–15 Ma), on which the older allochthonous formations have been thrust southward.

 

The Troodos Zone or the Troodos Ophiolite dominates the central part of the island, constitutes the geological core of Cyprus (Fig. 2) and has a characteristic elongated domal structure.  It was formed in the Upper Cretaceous (90 Ma ago) on the Tethys sea floor.  It is regarded as the most complete and studied ophiolite in the world.  It is a fragment of a fully developed oceanic crust, consisting of plutonic rocks (harzburgite, dunite, wehrlite, pyroxenite, gabbro and plagiogranite, Fig. 3), intrusive rocks (diabase), volcanic rocks (pillow lavas, Fig. 4), and chemical rocks.  The stratigraphic completeness of the ophiolite makes it unique.  It was created during the complex process of oceanic spreading and formation of the oceanic crust.  It emerged and was placed in its present position through complicated tectonic processes relating to the collision of the Eurasian plate to the north and the African plate to the south.  The diapiric rising of its core took place mainly with episodes of an abrupt uplift in the Pleistocene (2 Ma).

 

The Mamonia Zone or Complex appears in the Paphos district in the southwestern part of the island.  It constitutes a series of igneous, sedimentary and metamorphic rocks (Fig. 5), ranging in age from Middle Triassic to Upper Cretaceous (230–75 Ma).  These rocks, which are regarded as allochthonous in relation to the overlying autochthonous carbonate successions and the Troodos Ophiolite rocks, were placed over and adjacent to the Troodos Ophiolite during the Maestrichtian.

 

The Zone of the autochthonous sedimentary rocks, ranging in age from Upper Cretaceous through to Pleistocene (67 Ma to recent), covers the area between the Pentadaktylos and Troodos Zones (Mesaoria plain) as well as the southern part of the island.  Sedimentation begins with the deposition of the Kannaviou Formation (bentonitic clays, volcaniclastics), followed by the deposition of the Moni and Kathikas Formations (mélange).  Carbonate sedimentation begins from the Palaeocene (65 Ma) with the deposition of the Lefkara Formation, which includes pelagic marls and chalks (Fig. 6) with a characteristic white colour, with or without cherts.  The classic development of the Formation is represented by four members: Lower Marls; Chalks with layers of chert; massive Chalks (Fig. 7); and, Upper Marls.  The Lefkara Formation is followed by the Pakhna Formation (Miocene age, 22 Ma), which consists mainly of yellowish marls and chalks.  The colour of the rocks, the presence of calcarenitic layers and the occasional development of conglomerates are characteristics that differentiate the Pakhna Formation from the Lefkara Formation.  Sedimentation in the Pakhna Formation began and terminated in a shallow-water environment with the development of reef limestone (Terra Member at the base and Koronia Member at the top of the Formation, Fig. 8).  The deposition of the evaporites of the Kalavasos Formation followed in the Upper Miocene (Messinian, 6 Ma), as a result of the closure of the Mediterranean Sea from the Atlantic Ocean and the evaporation of its waters.  The Formation is composed of gypsum (Fig. 9) and gypsiferous marls that cover extensive areas.  With the reconnection of the Mediterranean Sea with the Atlantic Ocean (with the opening of the Gibraltar Strait), a new cycle of sedimentation began (Pliocene, 5 Ma).  The Nicosia Formation was deposited first and contains siltstones (grey and yellow) and layers of calcarenites and marls (Fig. 10).  This is followed by the Athalassa Formation (Pliocene–Pleistocene, 2 Ma) consisting of calcarenites, which are interlayered with sandy marls.  Finally, the Fanglomerate is a Pleistocene formation and includes clastic deposits (gravels, sand and silt).  The stratigraphic column of the Troodos Ophiolite and the autochthonous sedimentary cover is shown in Figure 11.



 

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