The Pre-Tertiary rocks of SW Cyprus

Abstract

The pre-Tertiary rocks of SW Cyprus consist of an autochthonous unit, composed of Campanian sediments, and an allochthonous assemblage containing igneous and sedimentary rocks of Triassic to Lower Cretaceous age, and some undated metamorphic rocks. The complex rests on a basement of Cenonanian to Campanian basic pillow lavas, which form the youngest unit of the Troodos Igneous Complex. The basal autochthonous sediments (Perapedhi Formation) consist of thin (less than 10 m) iron-rich shales (umbers), locally associated with cherts and manganese nodules. The overlying autochthonous sediments (Kannaviou Formation) comprise 500 m or more of abyssal mudstones and marls intercalated with tuffaceous sandstones containing also lithoclasts similar in lithology to the large allochthonous rock units that are now referred to as "Mamonia Allochthonous Complex" The volcanic elements in the Kannaviou Formation have been derived from an andesitic-dacitic source, extraneous to Troodos, and probably reflect the crustal instability that culminated in the emplacement of the Mamonia Allochthonous Complex. During this time the Troodos Massif was probably a submarine high, undergoing submarine weathering and local brecciation. The Mamonia Allochthonous Complex comprises Triassic alkali lavas associated with reef and pelagic limestones, metamorphic schists, serpentinites, peridotites, gabbros, Triassic turbiditic sandstones and packstones intercalated with shales, Jurassic cherts, shales and packstones, and Lower Cretaceous quartz sandstones intercalated in shales. The total sedimentary thickness is not more than a few hundred metres. The association is interpreted to be of deep-marine origin in general, but including also shallower, probably continental-margin related elements at its base and top. The allochthonous units were probably emplaced on southern Cyprus as olistolithic blocks or smallscale sheets, and as debris in Campanian-pre-Upper Maastrichtian times. Their regional distribution in Cyprus makes a proveance north of Troodos unlikely.