Associated Project

NaukaNaftogaz, Kyiv, Ukraine

Pliocene-Quaternary evolution of the NW Black Sea: tectonics, sea-level changes and their impact on regional basin architecture

Investigators: dr. Sergiy Stovba (NaukaNaftogaz); dr. Randell Stephenson (Amsterdam)

Brief description (details available by contacting dr. Sergiy Stovba)

Aims and objectives: Semi-enclosed basins situated at the end of major river discharges provide an unusually good record of the interaction between tectonics and sea level variations, in particular for the recent history of sediment dynamics. Delta depocentre migration and along-shelf sediment transport turn sediment point sources into continuous continental shelves and provide sediments to replenish coastlines. To understand how such processes affect margin architecture, it is necessary to make observations and develop stratigraphic models that combine deltaic sedimentation, shelf and slope dynamics with tectonism and sea-level variation.

The NW part of the semi-enclosed Black Sea basin provides a key case study for the study of active sink sedimentary processes and their interference with the dynamics of basins and orogens drained in the source area. The large scale sea-level drop and onset of a widespread anoxic event near the limit Eocene/Oligocene and the major sea-level changes recorded during the Pontian (Messinian crisis), late Pleistocene and Holocene demonstrate that this area is prone to sudden (or even catastrophic as in the Holocene) environmental changes. In particular the 1.2km sea-level drop recorded in the Pontian (Dinu et al., 2007) has apparently radically changed the style of sedimentation along the entire NW Black Sea basin from a widespread shelf-type of sedimentation to channelised deep sea fans. The point sources of these fans (e.g., Danube, Nipru/Dniepro) are erosional channels inherited from the Messinian low-stand that still represent today the main feeding source for the deep sea sediments.

An equally important feature currently shaping the geometry and distribution of sediments into the Black Sea basin is the large scale basin inversion which started in the late Eocene (e.g., Doglioni et al., 1996). In particular, the large scale thrust load of the Crimean margin (Finetti et al., 1988), actively changing the northern Black Sea margin, is rather poorly known (and debated) in terms of timing and effects on proximal and/or distal sedimentation, its interaction with the potential ongoing subsidence of the deeper part of the Black Sea and with the regional events caused by basin connectivity. Another major interest is the impact of the inherited, highly non-homogeneous pre-Eocene structure of the East-European margin (Saintot et al., 2006) into the recent evolution of the NW Black Sea margin.

In this context, the following objectives are relevant for the present project:

• correlation of major sea-level lowstand intervals across the NW margin of the Black Sea basin during the Pontian – Quaternary. These lowstands are clearly visible in places where strata were tilted due to tectonics or land sliding such as on the Romanian offshore, but are less obvious in places where disconformities are present such as on the Odessa shelf. What is particularly important is stratigraphic correlation, in order to derive coherent timing relationships across the entire shelf;
• deriving the long and short-wavelength interference of Pliocene-Quaternary Crimean tectonics on the post-Pontian change in sedimentary architecture of the NW Black Sea;
• to link quantitatively the sedimentation overspill events generated by the filling up the western Paratethys basins to the shift in sedimentation and subsidence observed on the onshore. Of special relevance is the study of the postulated Pliocene-Quaternary acceleration of subsidence, which can alternatively represent the effects of a shift in sedimentation rather than a tectonic phase.; and
• quantifying the geometry, amplitude and environmental impact of Pliocene-Quaternary landslides along the NW Black Sea basin.

Added value: The innovative aspects of the Associated Partnership are offered by:

• an integrated approach to the interplay between basin inversion and major environmental changes in active sedimentary basins;
• quantifying the Pliocene-Quaternary tectonics on the NW Black Sea and its impact on basin architecture;
• quantifying the effects of the Messinian sea-level drop in Paratethys basins and the consequent major sedimentary effects of the last 5 Myr; and
• exploring the potential impact of large scale land sliding on coastal management.

Methodologies/experiments: The methodology comprises two components:

• joint seismic sequence stratigraphic interpretation linking seismic lines across national boundaries to derive an integrated structural and sedimentological model for the post-Messinian evolution of the Black Sea and
• numerical modelling performed at the Vrije Universiteit Amsterdam to assess the effects of tectonics on recent basin geometry.

Deliverables and/or milestones:

• an integrated model of syn-tectonic sedimentary evolution along the entire NW Black Sea margin since the Pliocene and
• a model of interconnectivity between the various Paratethys basins and its impact on abrupt environmental changes

References:

• Dinu, C., Wong, H.K., Tambrea, D. and Matenco, L., 2005. Stratigraphic and structural characteristics of the Romanian Black Sea shelf. Tectonophysics, 410: 417-435.
• Doglioni, C., Busatta, C., Bolis, G., Marianini, L. and Zanella, M., 1996. Structural evolution of the eastern Balkans (Bulgaria). Marine and Petroleum Geology, 13: 225-251.
• Finetti, I., Bricchi, G., Del Ben, A., Papin, M., Xuan, Z., 1988. Geophysical study of the Black Sea area. Bull. Geofis. Teor. Appl. 30 (117–118), 197–234.
• Saintot, A., Stephenson, R.A., Stovba, S., Brunet, M.F., Yegorova, T. and Starostenko, V., 2006. The evolution of the southern margin of Eastern Europe (Eastern European and Scythian platforms) from the latest Precambrian-Early Paleozoic to the Early Cretaceous. In: D.G. Gee and R.A. Stephenson (Editors), European Lithosphere Dynamics. Geological Society Memoir No. 32, London, pp. 481-505.