
The Circum-Rhodope Belt is a major tectonic unit that surrounds both the Rhodope and the Serbo-Macedonian zones of the Alpine orogen in the northern Aegean region. The arc-related, supra-subduction zone Evros ophiolite represents the most important crustal element in the eastern part of the Circum-Rhodope Belt. A new U-Pb LA-ICP-MS zircon magmatic crystallization age of 174.6 ± 1.8 Ma obtained for the Agriani gabbro, together with the reviewed crystallization ages of other magmatic bodies reveal that the magmatic history of the Evros ophiolite spans 176 Ma to 169 Ma time interval. Reviewed ages of the medium to lowtemperature cooling history from 550 °C (40Ar/39Ar amphibole) down to 120 °C (fission-track apatite) show that it immediately followed the magmatic crystallization starting around 174 Ma and continued up to 140 Ma for the Evros ophiolite.
Floods and landslides are among the most significant natural hazards in Bulgaria, posing substantial risks to human life, infrastructure, and the environment. This study aims to assess the risks associated with these hazards, focusing on their frequency, intensity, and impact on human settlements, infrastructure, and the environment.
The main goal of the research is a comparative analysis between two of the most recognized methodologies for risk assessment. We implemented the framework in two adjacent coastal municipalities in southeastern Bulgaria. This study is focused on summer storms and landslides. The framework acknowledges that summer storms comprise several natural hazards, including high winds, storm surges, and significant precipitation levels. The impact of natural phenomena, such as landslides induced by substantial rainfall or severe storm surges, is also taken into account. The current approaches rely on established methodologies from international organizations and institutions, such as the Inter-American Development Bank (IDB), United Nations International Strategy for Disaster Reduction (UNISDR), and Joint Research Center – European Commission (EC-JRC). These approaches stress the significance of risk assessment and locally specific management plans. The findings point out that it requires integrated, multidisciplinary approaches to address the growing challenges posed by natural hazards in an increasingly uncertain environment. These methods not only improve our comprehension of risk factors but also make it easier for different stakeholders to work together.
In latest Tithonian times, in the Crassicollaria colomi Subzone, dominant Crassicollaria species suffered a decline. Next, the ultimate calpionellid crisis occurred in the Calpionella alpina Subzone, where practically nothing, but the taxon C. alpina, survived. The same succession of calpionellid associations and the same crisis has been demonstrated in all continents in a large body of literature, as we illustrate it herein. The event, and the base of the Alpina Subzone that it marks, is the outstanding level for definition of the Tithonian/Berriasian (J/K) boundary.
This level is also close to the original top of the “Portlandian”, d’Orbigny’s topmost Jurassic stage. And, in Tethys, close above the ammonite level (Jacobi Subzone) that was previously used to define the boundary. In the Jacobi Subzone, the appearance of the ammonite genus Delphinella acts as a proxy for the base of the calpionellid Alpina Subzone. In the Caribbean and Mexico, the Alpina Subzone is also proved. In the Andes, the Alpina subzone’s base lies close to the base of the ammonite Substeueroceras koeneni Zone, and it is marked by the last appearance of Calpionella elliptalpina, as it is at sites in Tethys. No other boundary level that has been suggested in the J/K interval has such a strong primary marker, and no other has so many proxies to support it.
The interaction of Ge-containing solutions with solid fossil fuel samples confirm its organic mode of occurrence. Based on the maximum sorption capacities, the samples follow the order: vitrain and xylain > peat (Romania) > bituminous coal > peat (Belarus) > lignite > semifusain. The results show the dependence between the sorption capacity of the studied samples and the pH medium, as well as the time of soaking. It was found that Ge is strongly associated with organic matter.
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