Eocene development of the northerly active continental margin of the Southern Neotethys in the Kyrenia Range, north Cyprus

• Published in: Geological Magazine
• Main Authors: Robertson, Alastair H. F., McCay, Gillian A., Taşlı, Kemal, Yıldız, Ayşegül
• Other Authors: Mühendislik Fakültesi
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press
• Subjects: Sedimentary Melange; Olistostrome; Easternmost Mediterranean; Eocene; Active Continental Margin; Planktonic foraminifera
• Online Access: https://hdl.handle.net/20.500.12451/5894; https://doi.org/10.1017/S0016756813000563

WOS: 000337751000008 We focus on an active continental margin related to northwards subduction during the Eocene in which sedimentary melange (`olistostromes') forms a key component. Maastrichtian -Early Eocene deep-marine carbonates and volcanic rocks pass gradationally upwards into a thick succession (<800 m) of gravity deposits, exposed in several thrust sheets. The lowest levels are mainly siliciclastic turbidites and debris-flow deposits. Interbedded marls contain Middle Eocene planktonic/benthic foraminifera and calcareous nannofossils. Sandstones include abundant ophiolite-derived grains. The higher levels are chaotic debris-flow deposits that include exotic blocks of Late Palaeozoic -Mesozoic neritic limestone and dismembered ophiolite-related rocks. A thinner sequence (<200 m) in one area contains abundant redeposited Paleogene pelagic limestone and basalt. Chemical analysis of basaltic clasts shows that some are subduction influenced. Basaltic clasts from unconformably overlying alluvial conglomerates (Late Eocene -Oligocene) indicate derivation from a supra-subduction zone ophiolite, including boninites. Taking account of regional comparisons, the sedimentary melange is interpreted to have formed within a flexurally controlled foredeep, floored by continental crust. Gravity flows including large limestone blocks, multiple debris flows and turbidites were emplaced, followed by southwards thrust imbrication. The emplacement was possibly triggered by the final closure of an oceanic basin to the north (Alanya Ocean). Further convergence between the African and Eurasian plates was accommodated by northwards subduction beneath the Kyrenia active continental margin. Subduction zone rollback may have triggered collapse of the active continental margin. Non-marine to shallow-marine alluvial fans prograded southwards during Late Eocene -Oligocene time, marking the base of a renewed depositional cycle that lasted until latest Miocene time. NERC We thank Dr Mehmet Necdet for encouragement with this work. Dr Nick Odling kindly assisted with the XRF analysis. We are also very grateful to Dr Hayati Koc for assistance with preparing diagrams. We thank Aynur Gurbuz (Mersin University of Advanced Technology, Education and Aplication Centre) for taking the SEM photographs of planktonic foraminifera. Dr Nurdan. Inan (Mersin University, Mersin) kindly determined the benthic foraminifera. Concerning the fieldwork, the first author acknowledges the support of the University of Edinburgh while the second author was supported financially by a NERC training award. The third and fourth authors thank their home institutions for financial support related to the laboratory-based biostratigraphical studies. The manuscript benefitted from reviews by Professor A. Lord and an anonymous referee. In addition, Dr T. C. Kinnaird provided some helpful comments on the manuscript.