In this article, we present the results of our study on archaeological slags found near the village of Krushevets, Southeast Bulgaria. Chemical analyses of the slags show a high Fe2O3 (40.11–54.57%) and SiO2 (29.32–42.28%) content, increased CaO content (3.01–6.51%), as well as very low quantity of SO3 (from 0.20% to 0.52%) and P2O5 (between 0.23% and 0.30%). The unbound residual copper in the samples is in an amount of 0.41% to 1.07%. The main phases composition of the slags are as follows: fayalite-type silicate phases with impurities, kirschsteinite and laihunite; pyroxenes of the augite-type and amorphous hosted glass; iron-oxide phases (magnetite and maghemite); and copper-containing phases (drops of unbound copper, relicts of ore minerals such as bornite, chalcopyrite), as well as newly formed phases, such as chalcocite, and copper-containing spherical aggregates. The studied samples are a by-product of copper extraction metallurgical activity. The raw material used was of copper-sulfide type with impurities of manganese-, calcium-, magnesium- and aluminium-containing minerals.
The study focuses on the quality of shallow groundwater in Bulgaria based on the content of major ions. To be safe for drinking purposes, their concentrations must not exceed the respective thresholds. The groundwater quality is assessed in terms of health hazard by a groundwater quality index (GWQI or WQI), and the respective map is presented. The results show that for the territory of Bulgaria, this index varies from 13 to 92. The highest values of this index (related to health hazard) are typical for the lower hypsometric zone of the country. The shallow groundwater in the zone of active water exchange is distributed as follows: waters of excellent quality, waters of good quality, waters of poor quality, and waters of very poor quality, covering 3%, 39%, 22%, and 31% of the whole area of the country, respectively. In this study, no estimates have been made for 5% of the territory of Bulgaria, which is characterized by the presence of very hard groundwater.
The Sredna Gora Zone holds a unique place in the tectonic subdivisions of the Balkanide orogen and its evolution is still a subject of debate. In the last twenty years, the idea of strike-slip-related evolution of the zone has been invoked. However, for the moment, the number of thorough studies where such a scenario is envisaged is limited, and substantial evidence based on detailed fieldwork is still missing. In this article, we discuss some of the major problems of the suggested wrench tectonic concept in the evolution of the central part of the Sredna Gora Zone. These are the character of some major shear zones in the area, to which strike-slip movements are attributed, and the transtension-transpression evolution scenario for the Chelopech and Panagyurishte basins. Despite refuting completely their wrench tectonic-related evolution, we confirm the presence of strike-slip and oblique slip structures cutting the sediments, whereas the time of their activity and role in the deformation of the basin fill are yet to be revealed. Finally, we present a model based on natural examples and analogue modeling, in which the long-lived dextral Maritsa shear zone represents a zone of localized strain partitioning, separating the opposite vergent thrust belts of the Rhodope to the south and the Sredna Gora and Balkan fold-thrust belt to the north, during oblique or possibly orthogonal convergence.
This study is based on primary lithological data from 96 boreholes and lithostratigraphic interpretation of 17 seismic profiles from the onshore part of the Dolna Kamchiya Basin, which belongs to the onshore sector of the Moesian Platform and comprises the south-easternmost part of the Southern platform zone. Nine formal Paleogene lithostratigraphic units were recognized (the Byala, Komarevo, Dvoynitsa, Beloslav, Dikilitash, Aladan, Avren formations, the Dolni Chiflik Member of the Avren Formation, and the Ruslar Formation). For visualization of their spatial relationships and revealing the deep structure of the basin, a 3D lithological model was created. In addition, new data on the lithology, thicknesses and ages of the units were provided.
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