Effects of large sea‐level variations in connected basins: theDacian–Black Sea system of theEasternParatethys

Abstract

Sea‐level changes provide an important control on the interplay between accommodation space and sediment supply, in particular, for shallow‐water basins where the available space is limited. Sediment exchange between connected basins separated by a subaqueous sill (bathymetric threshold) is still not well understood. When sea‐level falls below the bathymetric level of this separating sill, the shallow‐water basin evolution is controlled by its erosion and rapid fill. Once this marginal basin is filled, the sedimentary depocenter shifts to the open marine basin (outward shift). With new accommodation space created during the subsequent sea‐level rise, sediment depocenter shifts backwards to the marginal basin (inward shift). This new conceptual model is tested here in the context of Late Miocene to Quaternary evolution of the open connection between Dacian and Black Sea basins. By the means of seismic sequence stratigraphic analysis of the Miocene‐Pliocene evolution of this Eastern Paratethys domain, this case study demonstrates these shifts in sedimentary depocenter between basins. An outward shift occurs with a delay that corresponds to the time required to fill the remaining accommodation space in the Dacian Basin below the sill that separates it from the Black Sea. This study provides novel insight on the amplitude and sedimentary geometry of the Messinian Salinity Crisis (MSC) event in the Black Sea. A large (1.3–1.7 km) sea‐level drop is demonstrated by quantifying coeval sedimentation patterns that change to mass‐flows and turbiditic deposits in the deep‐sea part of this main sink. The post‐MSC sediment routing continued into the present‐day pattern of Black Sea rivers discharge.

Tectonic Models for the Evolution of Sedimentary Basins

“…The relative difference in rheological strength of the marginal and central parts of the basin is more pronounced in the eastern than in the western Black Sea. These predictions are in agreement with data mapping deformation in the Black Sea (e.g., Dondurur et al, 2013;Munteanu et al, 2012).…”

“…While fine clastic to pelagic Lower-Middle Miocene sediments are generally thin throughout the western Black Sea, higher subsidence rates are recorded during latest Miocene-Quaternary times Munteanu et al, 2012;Nikishin et al, 2003). The sea-level drop of the Messinian Salinity Crisis in the Mediterranean (e.g., Krijgsman et al, 1999) is recorded in the Black Sea by large-scale shelf erosion and massive progradation of clastics during the lower Pliocene transgressive and highstand, the estimated sea-level drop probably exceeding 1 km (e.g., Bartol and Govers, 2009;Bartol et al, 2012;Gillet et al, 2007;Hsü and Giovanoli, 1979;Munteanu et al, 2012). Rapid sea-level changes are also inferred for the Pliocene-Quaternary evolution of the western Black Sea (Lericolais et al, 2013;Winguth et al, 2000).…”

Timing of arrival of the Danube to the Black Sea: Provenance of sediments from DSDP site 380/380A

“…Furthermore, there is good agreement with the geology of the eastern Dacian Basin, which became a predominantly fluvial environment during the regional Romanian stage (4.15–1.8 Ma; van Baak, Mandic, Lazar, Stoica, & Krijgsman, ). Our results cast serious doubt on any scenario involving major erosion and transfer of large amounts of sediment from the Dacian and Pannonian basins to the Black Sea during the Messinian Salinity Crisis (Clauzon et al., ; Munteanu et al., ), which lasted from 5.971 Ma to 5.33 Ma (Roveri et al., ). Our study also highlights that a large volume of the sediments on the northwest Black Sea shelf was likely deposited prior to the arrival of the Danube into the basin.…”

“…The Northwest Black Sea contains the largest siliciclastic depositional system within the greater Black Sea basin, with a shelf comprising up to 4 km of Late Miocene to recent sediments (Munteanu, Matenco, Dinu, & Cloetingh, ). At present, the Danube is the largest sediment contributor to this system, supplying 88 MT of sediment per year, more than 50% of the total sediment input to the Black Sea basin (Jaoshvili, ).…”

TOPO-EUROPE: Understanding of the coupling between the deep Earth and continental topography

“…9). Observational studies across multiple basins and separating mountain chains combined with numerical modeling pointed to a significant impact of basin connectivity events on the architecture of all these Paratethys basins (e.g., Bartol et al, 2012;Leever et al, 2011;Munteanu et al, 2012; ter Borgh et al, 2013). The TOPO-ALPS project had the principal goal of establishing the erosion rates across the Alps over a range of timescales from decades to millions of years.…”