Origin of the Kyrenia Terrane, Northern Cyprus: Results of Detrital Zircon U-Pb Provenance Investigations in Triassic to Eocene Rock Units

Abstract:

Situated between Africa and Eurasia in the eastern Mediterranean, the island of Cyprus has developed on the northern margin of the southern Neo-Tethys by the accretion of three terrains, the Mamonia complex, the Troodos ophiolite, and the Kyrenia terrane. The latter comprises imbricated tectonic slices of Mezosoic-Cenozoic carbonate rocks, various clastic rock units and bimodal volcanic suites, alongside a thick Oligo-Miocene turbidite pile – the Kythrea flysch. This study was initiated with the aim of deciphering the provenance of Middle Triassic calcschist alongside Maastrichtian and Eocene sandstones of the Kyrenia terrane by detrital zircon U-Pb geochronology, in order to clarify its regional context. Our U-Pb geochronology data show that Precambrian-aged zircons in all three studied units cluster at the Neoproterozoic age interval (950-600 Ma). This Precambrian age profile resembles that of Paleozoic sandstone units of the Tauride block, as well as that of Paleozoic and Mesozoic sandstones found across North Africa. It is interpreted as reflecting the reworking of sand piles from the Taurides or any other peri-Gondwanan source. Phanerozoic-aged zircons cluster in four age groups: a small Silurian (~430 Ma) population appears in the Triassic and Maastrichtian units, Carboniferous (~300 Ma) and Triassic (~240 Ma) populations are conspicuous in all three units, and an Upper Cretaceous (~85 Ma) population significant in the Maastrichtian and Eocene units. Silurian and Carboniferous zircons are generally considered to represent north Paleo-Tethyan sources, although rare Carboniferous granitoids are recorded in the northern parts of the Anatolide-Tauride block, which resided at the southern margin of the Paleo-Tethys until the early Mesozoic. Possible sources for Triassic zircons are mainly found in the Aegean region with minor occurrences in the central Taurides, while sources for Upper Cretaceous zircons can be traced from the Pontides in the north to SE Anatolia in the south. Overall, while a provenance in the Taurides may account for the detrital zircon pattern of the Kyrenia, the presence of Paleozoic zircons points to an unusual paleogeography whereby rock units of the Kyrenia, now amidst the Neo-Tethys, were fed from a Paleo-Tethyan source already in the Triassic.