Cadomian and post-cadomian tectonics west of the Rhodope Massif – The Frolosh greenstone belt and the Ograzhdenian metamorphic supercomplex

The Frolosh Greenstone Belt (FGB) is traced at a distance of more than 200 km in the territories of Bulgaria, Macedonia and Serbia. It consists of various greenschist-facies rocks (actinolite schists, phyllites, calcareous schists, impure marbles, metasandstones, metadiabases, massive green rocks, etc.) of the Frolosh metamorphic complex with bodies of metabasites (including lherzolites), and inliers (retrogressed mica gneisses and migmatites) from the Ograzhdenian supercomplex. The complex is in­truded by bodies of gabbro (occasionally with ultramafic cumulates), diorites to granites (Struma diorite formation). U-Pb studies on zircons yielded Cadomian ages within the time span between c. 574 and 517 Ma. The Frolosh complex covers the ultrametamorphic (migmatized gneisses and amphibolites; tourma­line-biotite schists; quartzo-feldspathic gneisses; lensoid bodies of metaperidotites to norites) of the Ograzhdenian supercomplex. The Ograzhdenian rocks are intersected by diatectic metagranites over­printed by amphibolite-facies metamorphism. Dominant U-Pb ages vary between 470 and 430 Ma. The contact between the Frolosh complex and the Ograzhdenian supercomplex has been subject of long dis­cussion and controversial interpretations. Now we emphasize on the multistage developments of both complexes as demonstrated both by field evidence and isotopic dating. The Ograzhdenian supercomplex has been subject of Precambrian tectonometamorphism witnessed by Rb-Sr whole-rock isochron data and relict U-Pb zircon data. Ordovician to Silurian anatectites (metatectic migmatization, diatexis) are in­truded by Permo-Triassic granites. The contact between the Ograzhdenian supercomplex and the covering Frolosh complex is regarded as a thick complex zone of multistage tectonometamorphic development rather than a “razor-blade” surface of one-stage origin. As a boundary between suprastructure and infra­structure, it played an important role throughout the Phanerozoic, and acted as a screen with a steep ther­mal gradient during the Ordovician-Silurian anatexis and metamorphism in the Ograzhdenian supercom­plex. For to verify this hypothesis, new detailed structural and isotopic studies are needed

Temperature limits during irradiation in laser-assisted treatment of peri-implantitis – laboratory research

Introduction: Peri-implantitis is a relatively new and difficult disease that is becoming more common. Of the different therapeutic options to manage this condition, lasers show certain advantages over other therapeutic alternatives because of their antibacterial potential. Aim: The aim of the present study was to investigate the temperature rise of implant surfaces, soft tissues, and bone during irradiation with diode, CO2, and Er:YAG lasers. Materials and methods: Ten implants inserted in biological models were irradiated with three laser systems with different parameters: a diode laser (980 nm) with power levels of 0.75 W and 1.6 W; a CO2 laser (10600 nm) with power levels of 252 W and 241 W; and an Er:YAG laser (2940 nm) with power levels of 1.5 W, 6.8 W, and 7.5 W. The temperature rise was measured using a specially designed thermal probe (type K thermocouple) with accuracy of ±0.1°C over the range from 20°C to 80°C. The temperature was measured at 5 points – in the implant body, in the mucosa, in the middle part of the implant, in the implant apex, and in the bone around the implant apex. Measurements were obtained at 1 minute working interval. Results: Diode and CO2 lasers with both parameters used increased significantly the temperature of more than 46°C, whereas the temperature in the Er:YAG laser group was less than 30°C. There was a statistically significant difference between diode, CO2, and Er:YAG lasers in favor of the erbium laser. Conclusions: The Er:YAG laser demonstrates the best thermal properties during irradiation of the implant surface. The three working modes tested – 1.5 W, 6.8 W, and 7.5 W – provide safe intervention on both the soft and bone tissues of the implant interface and on the implant itself

SIVIRIS FORMATION (UPPER OLIGOCENE - LOWER MIOCENE), A NEW LITHOSTRATIGRAPHIC UNIT, KASSANDRAS PENINSULA (CHALKIDIKI, NORTHERN GREECE)

Upper Oligocene - Lower Miocene marine sediments are found and proven for the first time in Chalkidiki Peninsula. They are designated as Siviris For- mation and are dated by their calcareous nannofossil content

Discovery of the oldest European ruminant in the late Eocene of Bulgaria: Did tectonics influence the diachronic development of the Grande Coupure?

International audienceWe describe the oldest known European ruminant, Bachitherium thraciensis sp. nov., from late Eocene (latest Bartonian or early Priabonian) strata in Bulgaria. The new specimen, which possesses the most primitive dental morphology known in the Bachitheriidae family, predates its western European relatives by at least 4.5 Myr. The discovery suggests that ruminants dispersed into Europe in a series of east to west waves, preceding and following the Eocene–Oligocene boundary. Probably originating from Asia, the oldest ruminant (reported here) migrated into southeastern Europe. During a second wave, comprising the Grand Coupure dispersal event, ruminants moved into western Europe at the Eocene–Oligocene boundary. A third wave composed by Bachitheriidae and Tragulidae arrived in western Europe, 2 Myr later, in the earliest Oligocene. The origin of this east to west diachronism was probably facilitated by orogenesis that, episodically, allowed dispersal of ruminants from Asia, through southeastern Europe, and into western Europe, in what we herein term the “Bachitherium dispersal event”. However, none of the abundant perissodactyl fauna from southeastern Europe migrated to western Europe during this time, because, like their relatives in central Asia, they may not survive to terminal Eocene cooling and aridity

In Vitro Study of Temperature Changes in Pulp Chamber During Root Planing Procedure Using Er:YAG Laser

Aim: To assess temperature changes at specified time intervals during Er:YAG laser scaling and root planing of surfaces with dental calculus

Marine gateway vs. fluvial stream within the Balkans from 6 to 5 Ma

International audienceSince the discovery of calcareous nannofossils, dinoflagellate cysts and planktonic foraminifers in deposits from the Dacic Basin, intensive research has been performed in order to evidence which gateway this microplankton used to connect Paratethys and the Mediterranean prior and after the Messinian Salinity Crisis (MSC). Such a gateway is also to be regarded at the origin of successive influxes of Paratethyan organisms (molluscs, ostracods, dinoflagellates) into the Mediterranean Basin ("Lago Mare" events). Observing that the İ stanbul area, usually proposed for this purpose, was inefficient, we examine the succession of marine well-dated pre-MSC and post-MSC deltaic deposits through the Balkans, from northern Greece to southern Romania, that constitutes a reliable candidate for such a marine corridor, the origin of which was caused by the regional tectonic extension. The reconstructed palaeogeography for high sea level episodes that encompassed the MSC clarifies the context of the so-called North Aegean Lake. This marine gateway probably evolved as a powerful river during the peak of the MSC, contributing to the deposition of clastics in the hydrocarbon Prinos Field. A tectonically controlled subsidence to the north and south of the Skopje region caused the closure of such a gateway