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Abstract: Detailed lithological and micropaleontological studies were performed on several cores from the Romanian Black Sea shelf, located in front of the Danube Delta, in front of the Razelm–Sinoe lagoonal complex, close to the Eforie beach, as well as on the Romanian inner shelf. All the studied cores are situated at a water depth varying between 12m and 67m. The purpose of the investigations was to reveal Upper Holocene lithological changes and the associated calcareous nannoplankton fluctuations in a very shallow marine setting such as the Romanian Black Sea inner shelf. The youngest Holocene unit or “Shallow Unit” is composed of alternating sequences of mud, silt, clay and coquina layers, containing marine mollusc faunas. The upper part of the Shallow Unit contains blooms of the nannoplankton species Emiliania huxleyi, while its lower part yields, besides common E. huxleyi, rare specimens of Braarudosphaera bigelowii. The Shallow Unit overlies a “shell hash layer”, mainly made by coquinas, containing mixing marine and brackish mollusc faunas. Towards the upper part of this level, monospecific assemblages with B. bigelowii were observed in a layer rich in carbonate acicular crystals. The Shallow Unit partly corresponds to the Unit 1 (finely laminated coccolith ooze) and Unit 2 (sapropelic sediments) of slope and basinal settings of the Black Sea. The layer rich in carbonate acicular crystals could be a shallower equivalent of the oldest layer of aragonite bands placed at the lower part of the Unit 2 in deep parts of the Black Sea. In the analyzed cores, the oldest lithological unit (Unit 3, the muddy clay sediments deposited in a brackish to freshwater environment) is characterized by the deposition of green-yellowish clay devoid of any Holocene calcareous nannoplankton species and containing brackish mollusc faunas. Based on nannofloral fluctuations, an increasing salinity from the base towards the upper part of the Shallow Unit may be supposed, together with the progressive establishment of a stable marine setting, similar to today. [Copyright &y& Elsevier]

This study describes the fluctuation pattern in Late Holocene microfaunal (i.e. foraminifera and ostracods) and nannofloral assemblages of two cores collected from the Romanian Black Sea shelf, at a water depth of 28 and 66 m, respectively. The lithology of the cores is mainly characterised by blackish muds, alternating with thin, centimetres-thick sand and coquina layers. The microfaunas are dominated by brackish foraminiferal and ostracod assemblages that are still common in the actual Black Sea communities, living nowadays at water salinity lower than 18 ‰. In the shallower water Site EF 08-01, the abundance ratio between Caspian and Mediterranean ostracods is 0.7, while in the deeper water Site BS 08-055, the abundance ratio between Caspian and Mediterranean ostracods is 0.01. These data argue for the dominance of Mediterranean ostracod fauna with lower abundance in shallower environments of the Black Sea and with a very high abundance in the deeper parts of the internal shelf, i.e., at a water depth of 66 m. Based on the calcareous nannoplankton fluctuation, four Nannofloral Intervals were identified, which indicate a gradual salinity increase of the surface waters during the deposition of the Late Holocene Shallow Unit. In the same interval, the benthic microfaunas (ostracods and foraminifers) argue for a more stable salinity environment in the two studied cores from the Black Sea inner shelf [ABSTRACT FROM AUTHOR]

The relation between the grain size composition TOC (total organic carbon) concentration was examined by linear and non-linear regression analysis of analytical data for more than 500 sediment samples from the NW Black Sea. A significant dependency of the TOC concentration on the percentages of clay and especially the <16 μm fraction (clay plus fine and very fine silt) was identified, the model best fitting the analytical data being exponential. Three groups of sediment samples were identified using the K-means clustering technique, the deep sea sediment samples being clearly singled out. [ABSTRACT FROM AUTHOR]

The investigations focused on two profiles from the Black Sea, placed in front of the Portiţa Mouth and in the south-eastern part of the Sahalin Island. Up to 40 m water depth, the samples from the Portiţa profile contain only reworked Mesozoic and Cenozoic calcareous nannoplankton taxa. In the same profile, the bloom of the calcareous nannoplankton species Emiliania huxleyi, together with abundant benthic foraminiferal taxa, were recorded in the first 11 cm of sediments, at below 40 m water depth. All the samples collected in the SE of Sahalin Island contain only Mesozoic and Cenozoic reworked calcareous nannoplankton taxa; no marine assemblages in situ were remarked. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Summary: In this work, an interferometric ALOS PalSAR dataset acquired between 2007 and 2010 is used to measure water level changes for the first time within a hydrographical unit of the Danube Delta in Romania at the Black Sea. When the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique was applied, it revealed a previously unknown and spectacular dynamic of the water levels in Danube Delta. The results are presented in the form of water level change maps for different periods of time. The DInSAR measurements for a number of locations are compared with extrapolated water level change values obtained from an existing mathematical model of the hydrological regime in the Danube Delta. The comparison shows a very good correlation between DInSAR measurements and the mathematical model, showing that this method using L-band ALOS PalSAR data and applied to a wetland area of Danube Delta can be used to increase the spatial density of water level measurements and contributes to a better understanding of hydrological processes. [ABSTRACT FROM AUTHOR]