Ruthenium-based complexes containing a benzimidazolium tag covalently connected to N-heterocyclic carbene ligands: environmentally friendly catalysts for olefin metathesis transformations.

International audienceTwo ruthenium-based pre-catalysts containing an ionic tag covalently connected to a N-heterocyclic carbene (NHC) ligand are reported. These novel complexes, bearing a polar benzimidazolium group, are air-stable and can be easily prepared from commercially available reagents. The quaternary benzimidazolium tag allows the efficient separation of ruthenium waste from the metathesis product after reaction. Application in several olefin metathesis transformations leads to desired products of high purity, which exhibit ruthenium contamination levels as low as 1 ppm after simple filtration through a pad of silica gel

Miocene basin opening in relation to the north-eastward tectonic extrusion of the ALCAPA Mega-Unit

The opening and evolution of the Western Carpathians Miocene basins was closely related to the north-eastward tectonic extrusion of the ALCAPA Mega-Unit lithosphere caused by the final stage of collision of the Eastern Alpine–Western Carpathian orogenic system with the European Platform and Alpine convergence with the Adria plate. The roll back effect of the oceanic or thinned continental crust of the Magura–Krosno realms, subduction below the front of the Carpathians in the north-east, east and relative plate velocities led to gradual stretching of the overriding micro-plates (defined as the ALCAPA and Tisza Dacia Mega-Unit). Diverse movement trajectories of the ALCAPA crustal wedge individual segments (Eastern Alps, Western Carpathians, and Northern Pannonian domain) were accompanied by several counter-clockwise rotational phases. Beside the interpreted Early Miocene “en-block” counter-clockwise rotation, most of the rotations in the Central Western Carpathians were caused by “domino-effect tectonics” inside strike-slip zones and took part in the basin opening, which was in most cases followed by rapid subsidence

Neogene palaeogeography and basin evolution of the Western Carpathians, Northern Pannonian domain and adjoining areas

The data on the Neogene geodynamics, palaeogeography, and basin evolution of the Western Carpathians, Northern Pannonian domain and adjoining areas (ALCAPA Mega-unit) are summarized, re-evaluated, supplemented, and newly interpreted. The proposed concept is illustrated by a series of palinspastic and palaeotopographic maps. The Miocene development of the Outer Carpathians reflects the vanishing subduction of the residual oceanic and/or thinned continental crust. A compression perpendicular to the front of the orogenic system led to the closing of residual flysch troughs and to accretionary wedge growth, as well as to the development of a foredeep on the margin of the European Platform. Docking of the Outer Western Carpathians accretionary wedge, together with the Central Western Carpathians and Northern Pannonian domain, was accompanied by stretching of the overriding microplate. An orogen parallel and perpendicular extension was associated with the opening and subsidence of the Early and Middle Miocene hinterland (back-arc) basin system that compensated counter-clockwise rotations of the individual crustal fragments of ALCAPA. The Late Miocene development relates to the opening of the Pannonian Basin System. This process was coupled with common stretching of both ALCAPA and Tisza-Dacia Mega-units due to the pull exerted by subduction rollback in front of the Eastern Carpathians. The filling up of the hinterland basin system was associated with thermal subsidence and was followed by the Pliocene tectonic inversion and consequent erosion of the basin system margins, as well as part of the interior

The Central Paratethys palaeoceanography : a water circulation model based on microfossil proxies, climate, and changes of depositional environment

A comprehensive "model" of the semi-closed Central Paratethys Sea history was proposed for the entire time span of 25 Ma. Publications and datasets of the last decades were compiled and reviewed in the light of the Western Carpathian basins record, reflecting its changing palaeogeography, palaeoenvironment, and water circulation regimes. Moreover, a set of modified palinspastic palaeogeographic maps were reconstructed taking into account the enormous changes in depositional systems and sedimentary facies, reflecting the tectonic events from the Oligocene to Miocene. The study discusses possible gateways/straits assuming two way circulations, where the surface and deep water can be exchanged between the Mediterranean, Central Paratethys, and the Eastern Paratethys. It is suggested, that a good correlation between the regional Central Paratethys and the standard Mediterranean zonations based on planktic organisms can be achieved only in sequences deposited during anti-estuarine circulation regimes. Correlation of sequences deposited during the estuarine circulation of water masses becomes problematic, making hard to define above all the Early/Middle Miocene boundary. To solve problems of the regional biostratigraphy, and the definition of correlation levels between the Mediterranean, Central Paratethys, and Eastern Paratethys, the existing and new Sr-isotope dating was used as well. Dating of specific sediments of low oxic conditions or evaporitic events was also used as time horizons for the Central Paratethys