Eocene to middle Miocene contourite deposits in Cyprus: A record of Indian Gateway evolution Hernández Molina, Francisco Javier Rodríguez Tovar, Francisco J. Deep-marine sedimentation Bottom currents Contourites Cenozoic Cyprus Indian Gateway Acknowledgements This work was funded through the Joint Industry Project (JIP) supported by BP (United Kingdom), ENI (Italy), TOTAL (France), ExxonMobil (United States), Wintershall Dea (Germany) and TGS (United Kingdom) within the framework of “The Drifters” Research Group at Royal Holloway University of London (RHUL), and it is related to the projects CTM 2012-39599-C03, CGL2016-80445-R and CTM2016- 75129-C3-1-R. Financial support of the Deutsche Forschungsgemeinschaft (DFG) is gratefully acknowledged (HU 804/11-1). We thank the Cyprus Geological Survey for scientific collaboration and support, in particular Costas Constantinou and Efthymios Tsiolakis. We thank A. Creaser, L. Hyslop (RHUL), D.A.W. Stow (Heriot-Watt University) and A. Viana (PETROBRAS) for valuable help and discussions during field campaigns. We are also grateful to S. Suklap and B. Docherty for their analysis on microfacies during their MSc. in 2016. Thanks to Dr. G. Blackbourn (Blackbourn Geoconsulting) for his petrographic analysis; F. Sierro (Univ. Salamanca, Spain), RPS Energy Ltd and PalaeoVision Ltd for their biostratigraphic analysis of the samples and A. Maestro (IGME, Spain) for the basemap in Fig. 1. A. de la Vara’s contribution is based on work done during her PhD at Utrecht University, supervised by Paul Meijer. We thank the editor, Gabriel Tagliaro and one anonymous reviewer for their positive comments which helped us to improve considerably our manuscript. Bottom current deposits (contourites) form in association with modern-day or ancient oceanic gateways. A paucity of examples in the ancient record and the lack of consensus on diagnostic criteria for differentiating them from other deepwater deposits limit our understanding of how they may record past global oceanic circulation, tectonic events and gateway evolution. This work describes an exceptional example of Eocene to middle Miocene deep-marine deposits located both onshore and offshore deepwater environments around the island of Cyprus. Multidisciplinary approaches were used to discriminate contourite facies associations, propose a sedimentary model, and interpret the relations with regional tectonics and the evolution of the nearby Indian Gateway. Contourite deposits appear in late Eocene to middle Miocene intervals interstratified with pelagic/hemipelagic sediments, turbidites and mass-transport deposits (MTDs). These deepwater deposits developed along a slope basin located on the upper plate of an active margin, evolving from a wide basin formed during a period of tectonic quiescent into a series of shallowing-upward, segmented sub-basins affected by compressional stress. The present study proposes a sedimentary model in which two contourite depositional systems developed: first in the Eocene (dominated by finer-grained contourites), and then during the latest Oligocene to middle Miocene (dominated by coarser-grained contourites). Both systems were buried by extensive marl deposits and record the respective influence of deep (circulating NW) and intermediate (circulating SE) water masses. The long-term evolution of the contourites reflects tectonic events that enhanced subduction processes south of Cyprus as well as exchange between the Neotethys Ocean and the Indian and Atlantic Oceans —until the final closure of the Indian Gateway by the end of the middle Miocene, when a new circulation pattern was established with the formation of the Mediterranean Sea. The contourites described here represent bi-gradational sequences that normally form in association with contouritic drifts, sometimes having the asymmetric top-cut sequence characteristics of plastered drifts and contourite terraces. The coarser (sandy) contourites, formed from the latest Oligocene to middle Miocene, consist of three packages associated with compressive and flexural phases. They pertain to I) Chattian (late Oligocene); II) Aquitanian/Burdigalian (early Miocene) and III) Langhian (middle Miocene). Evidence of enhanced bottom current episodes occurs toward the top of these packages before they are buried by later dominant marl deposits. The sandy contourites thus formed during the compressive phases, whereas the predominately finer-grained units formed during later flexural phases. The intermittent turbidites and MTDs (developed during compressional phases in combination with pelagic/hemipelagic sediments) represent the sediment supply for the contourite deposits after their winnowing and / or reworking. Our research found that the diagnostic criteria for discriminating ancient bottom current deposits from other deepwater deposits are related primarily to variations in sedimentary processes, current behaviour and its velocity, sedimentation rates and paleoenvironmental conditions. This highlights the importance of primary sedimentary structures, microfacies and ichnological features in making determinations at the sedimentary facies scale. Due to their common occurrence, sedimentary thickness (30-40 m), potential porosity and permeability, sandy contourites can form deepwater reservoirs for energy geosciences. In summary, this work demonstrates the role of plate tectonics and oceanic gateways in driving the paleo-oceanic circulation that, in turn, controls sedimentary processes and shapes the morphology of oceanic basins and continental margins. It also allows for comparison with other present-day and ancient continental margin deposits. Future high-resolution approaches and analyses of other geological settings could help resolve the sedimentary architectures of similar deepwater systems in terms of episodic tectonic processes —involving compressive-flexural stress variations. They control the Earth’s surface environment (sea-level, climate and oceanic circulation) over time by influencing sediment supply, packages of strata and types of contourite deposits. 2022-11-30T11:26:42Z 2022-11-30T11:26:42Z 2022-11-09 info:eu-repo/semantics/article F.J. Hernández-Molina et al. Eocene to middle Miocene contourite deposits in Cyprus: A record of Indian Gateway evolution. Global and Planetary Change 219 (2022) 103983 [https://doi.org/10.1016/j.gloplacha.2022.103983] https://hdl.handle.net/10481/78207 10.1016/j.gloplacha.2022.103983 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier