BLACKGATE

BlackGate aims to address fundamental questions concerning the dynamic evolution of the Mediterranean-Black Sea (MBS) gateway and its paleoenvironmental consequences. The importance of Mediterranean connectivity has been recognised, and several accepted IODP projects (IMMAGE, DEMISE) are currently directed at a better understanding of the Miocene gateway systems that led to the rise and demise of the Mediterranean Messinian Salinity Crisis, the youngest and largest salt giant in Earth history, and its consequences for global climate change. The missing link for a comprehensive understanding is the poor constraints on the hydrological fluxes through the Mediterranean-Black Sea gateway, derived from a huge catchment that at times drained much of Europe and Asia. This gateway also drives the Pliocene-Quaternary circulation patterns in the Black Sea and governs its status as the world’s largest example of marine anoxia. The exchange history of the MBS gateway is poorly constrained because continuous Pliocene-Quaternary deposits are not exposed on land adjacent to the Black Sea or North Aegean. Gateway exchange is controlled by climatic (glacio-eustatic driven sea level fluctuations) and tectonic processes in the catchment (linking the Black and Caspian seas) as well as tectonic propagation of the North Anatolian Fault zone in the gateway area itself. Changes in MBS connectivity trigger dramatic paleoenvironmental and biotic turnovers. Drilling a Messinian to Recent transect in the Aegean, Marmara and Black seas will recover high-amplitude records of continent-scale hydrological changes during glacial-interglacial cycles, marine and fresh water fluxes, biological turnover events, patterns and processes of anoxia, chemical perturbations and carbon cycling, growth and propagation of the NAF, existence of land-bridges for Africa/Asia-Europe mammal migration and presence/absence of water exchange during the Messinian salt giant. We propose to use a MSP to drill three sites, one on the Turkish margin of the Black Sea (Arkhangelsky Ridge 400mbsf), one on the southern margin of the Sea of Marmara (North Imrali Basin 750mbsf) and one in the Aegean (North Aegean Trough 650mbsf). All sites target Quaternary oxic-anoxic marl-sapropel cycles. Pliocene lacustrine sediments and mixed marine-brackish Miocene sediments will be recovered from the Black Sea and Aegean. MSP drilling is required because JOIDES Resolution cannot pass under the Bosporus bridges. The wider scientific objectives are in line with the aims and scope of the IODP overall Science Plan, Illuminating Earth’s Past,
Present, and Future, and relate specifically to the themes Earth’s climate, deep life and geohazards.