The interplay between tectonics, sediment dynamics and gateways evolution in the Danube system from the Pannonian Basin to the western Black Sea

Abstract

Understanding the natural evolution of a river-delta-sea system is important to develop a strong scientific basis for efficient integrated management plans. The distribution of sediment fluxes is linked with the natural connection between sediment source areas situated in uplifting mountain chains and deposition in plains, deltas and, ultimately, in the capturing oceans and seas. The Danube River-western Black Sea is one of the most active European systems in terms of sediment re-distribution that poses significant societal challenges. We aim to derive the tectonic and sedimentological background of human-induced changes in this system and discuss their interplay. This is obtained by analysing the tectonic and associated vertical movements, the evolution of relevant basins and the key events affecting sediment routing and deposition. The analysis of the main source and sink areas is focused in particular on the Miocene evolution of the Carpatho-Balkanides, Dinarides and their sedimentary basins including the western Black Sea. The vertical movements of mountains chains created the main moments of basin connectivity observed in the Danube system. Their timing and effects are observed in sediments deposited in the vicinity of gateways, such as the transition between the Pannonian/Transylvanian and Dacian basins and between the Dacian Basin and western Black Sea. The results demonstrate the importance of understanding threshold conditions driving rapid basins connectivity changes superposed over the longer time scale of tectonic-induced vertical movements associated with background erosion and sedimentation. The spatial and temporal scale of such processes is contrastingly different and challenging. The long-term patterns interact with recent or anthropogenic induced modifications in the natural system and may result in rapid changes at threshold conditions that can be quantified and predicted. Their understanding is critical because of frequent occurrence during orogenic evolution, as commonly observed in the Mediterranean area and discussed elsewhere.

Building and exhumation of the Western Carpathians: New constraints from sequentially restored, balanced cross sections integrated with low‐temperature thermochronometry

“…This regional extensional regime could have been triggered by a combination of deep lithospheric processes, also controlling the Miocene extension and development of the Pannonian Basin [ Fodor et al ., ; Horváth and Cloetingh , ]. Back‐arc formation occurred in the absence of absolute plate motions, since shortening has been entirely accommodated by interior extension [ Horváth et al ., ; Matenco et al ., ]. These processes are driven by the occurrence of inherited subducted slabs [ Bennett et al ., ; Martin and Wenzel , ; Wortel and Spakman , ], mantle upwelling inducing passive extension [ Huismans and Beaumont , ], and the associated dynamic topography mechanisms [ Burov and Cloetingh , ; Horváth et al ., ; Balázs et al ., ].…”

Extensional Polarity Change in Continental Rifts: Inferences From 3‐D Numerical Modeling and Observations

“…The Pannonian Basin of Central Europe (Figure ) is a continental back‐arc basin (Horváth et al, , and references therein), where the ~220–270 km of early to late Miocene extension (Balázs et al, ) was driven by the subduction and associated roll‐back that took place in the Carpathians and/or Dinarides (Matenco et al, ). The Miocene extension followed pre‐Neogene opening and then subsequent closure of two oceanic realms, a northern branch of the Neotethys and the Alpine Tethys (Figure a, Csontos & Vörös, ; Schmid et al, ).…”

U‐PB Detrital Zircon Geochronology of the Lower Danube and Its Tributaries: Implications for the Geology of the Carpathians

“…An Eocene arc is well developed in the Rhodope Mountains to the south, but the current hydrographic network or even known ancient ones (Matenco et al, 2013) do not link that source area to the Danube or its lower tributaries. Possibly, earlier links between various basins of the Paratethys (Matenco et al, 2016) may have brought zircons from such a far source area into the lower Danube's current basin. There is no obvious resolution to the question as to whether a previously continuous Paratethys could have transported laterally a significant amount of material from west of the Romanian Carpathians; there are no sedimentological data from the Dacian basin to support or refute that.…”

“…By comparing the known incomplete geologic record of the basement in the Carpathians with the limited but spatially significant collection of zircon ages from the most important rivers draining the Carpathian Mountains and the lower Danube itself, we aim to detect what is missing from the regional geologic knowledge and where to target future localized studies of the basement. Here we focus on the Danube and its tributaries that drain the easternmost segment of the Carpathian Mountains in Romania (Matenco et al, 2016;Radoane et al, 2003). The ability to measure large numbers of zircons by in situ mass spectrometry, mostly by laser ablation ICP-MS (Gehrels et al, 2008), has turned DZ chronology into one of the most widely used quantitative provenance tools.…”