The Zone of the autochthonous sedimentary rocks, ranging in age from the Upper Cretaceous to the Pleistocene (70 Ma to recent), covers the area between the Keryneia Terrane and Troodos Terrane (Mesaoria) as well as the southern part of the island. It consists of bentonitic clays, volcaniclastics, melange, marls, chalks, cherts, limestones, calcarenites, evaporites and clastic sediments.
The geological history of Cyprus from the Upper Cretaceous (70 Ma) is characterised by marine sedimentation in a sea which becomes gradually more shallow. Sedimentation begins with the deposition of the Kannaviou Formation (bentonitic clays, volcaniclastics), followed by the deposition of the Moni and Kathikas Formations. Overlying the Mamonia Complex rocks, there is an allochthonous sedimentary formation, known as Kathikas Formation, which is directly related to the emplacement of the Mamonia Complex (melange). Carbonate sedimentation begins in the Palaeocene (65 Ma) with the deposition of the Lefkara Formation, which includes pelagic marls and chalks with 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 and Upper Marls.
The Lefkara Formation is followed by the Pachna Formation (Miocene, 23-7 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 Pachna from the Lefkara Formation. Sedimentation in the Pachna Formation began and terminated in shallow-water environments with the development of reefal limestones (Terra Member at the base and Koronia Member at the top of the Formation).
The deposition of the evaporites of the Kalavasos Formation followed in the Upper Miocene (Messinian, 7 Ma) as a result of the isolation of the Mediterranean Sea from the Atlantic Ocean and the evaporation of Mediterranean sea water. The Formation is composed of gypsum and gypsiferous marls that cover extensive areas. Gypsum occurs in four types: sugary (crystalline), laminated (‘marble’), selenite (transparent with large twin crystals) and alabastre (massive semitrasparent).
With the re-connection of the Mediterranean Sea with the Atlantic Ocean, 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, marls and calcarenites interlayered with sandy marls. Finally, the Fanglomerate is a Pleistocene formation and includes clastic deposits (gravels, sand and silt).
The clastic sediments are the most important aquifers of the island. These are mostly developed in broad valleys and river deltas. Such aquifers are those of western and eastern Mesaoria, Akrotiri and Pafos. Aquifers are also developed in porous rocks such as calcarenites, in limestones and gypsum that are characterised by karst, and in fractured rocks such as chalks, limestones, etc.
The sedimentary rocks are the main sources of the industrial minerals of the island. The main industrial minerals include gypsum (used in the cement production), brick clays, umber, ochre and terra verte (natural pigments), marls and chalks (cement production), bentonitic clays (various industrial uses), building stone, celestite and magnesite.