Formation of a Late Cretaceous continental margin arc and an Early Cenozoic back-arc basin in the Kyrenia Range, northern Cyprus related to S-Neotethyan subduction

Abstract

<p>Field, geochemical and geochronological research on Late Cretaceous and Early Cenozoic volcanic rocks in Kyrenia Range provide constraints on the tectono-magmatic evolution of the northerly, active continental margin of the Southern Neotethys. Field mapping in the western Kyrenia Range demonstrates that frontal (southerly) thrust sheets are dominated by felsic volcanogenic rocks. U-Pb zircon dating indicates that the felsic volcanics erupted at 72.9 ± 1.0 Ma (Late Campanian). These volcanics are interpreted as the products of sub-aqueous continental margin arc volcanism based on geochemical evidence. The exposed arc volcanics are somewhat younger than arc-derived volcaniclastic sediments in W Cyprus (80.1 ± 1.1 Ma), and are also younger than arc-related granitic rocks (88-82 Ma) cutting the Tauride active continental margin (Malatya-Keban platform) in SE Turkey. Structurally higher (more northerly) imbricate thrust sheets include Late Cretaceous (Maastrichtian) and Early Cenozoic basalts that are underlain by a Mesozoic continental carbonate platform (metamorphosed), and interbedded with pelagic and redeposited carbonates that formed in an active continental margin setting. The basalts have within-plate geochemical characteristics, although with a variable subduction influence in some areas (e.g., western Kyrenia Range) that could be either be contemporaneous or inherited from Late Cretaceous (c. 70-80 Ma) subduction. Modern and ancient comparisons (e.g., Tyrrhenian Sea) suggest that the basaltic rocks represent incipient, extensional marginal basin formation. Integration with comparable evidence of continental margin arc magmatism in SE Turkey and elsewhere provides a picture of arc magmatism and marginal basin formation along an active continental margin, prior to collision during the Miocene.</p>