Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.153
D. Sinnyovsky, D. Vangelov
Lower Jurassic fossil-bearing red limestone with abundant belemnite rostra is exposed in the form of olistoliths included in the Middle Jurassic Kotel Olistostrome Formation in the surroundings of the town of Kotel in the East Balkan. Following the widely recognized Tethyan “ammonitico rosso” facies, we propose to formalize this distinctive red fossiliferous level as a lithostratigraphic marker under the name “belemnitico rosso”. This will contribute to the creation of attractive geosites of scientific and educational value with great interpretive potential for public understanding of science, as well as “ex situ” geodiversity elements used as building stones in construction. The creation of original geotourism products under the brand name of the future “East Balkan” Geopark seeks to make geology accessible to all. It is quite possible that someday, the new term will gain widespread popularity and will bring awareness to the geopark where it was first defined.
{"title":"The “Belemnitico rosso” facies in the East Balkan – a proposal \u0000of lithostratigraphic formalization","authors":"D. Sinnyovsky, D. Vangelov","doi":"10.52215/rev.bgs.2022.83.3.153","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.153","url":null,"abstract":"Lower Jurassic fossil-bearing red limestone with abundant belemnite rostra is exposed in the form of olistoliths included in the Middle Jurassic Kotel Olistostrome Formation in the surroundings of the town of Kotel in the East Balkan. Following the widely recognized Tethyan “ammonitico rosso” facies, we propose to formalize this distinctive red fossiliferous level as a lithostratigraphic marker under the name “belemnitico rosso”. This will contribute to the creation of attractive geosites of scientific and educational value with great interpretive potential for public understanding of science, as well as “ex situ” geodiversity elements used as building stones in construction. The creation of original geotourism products under the brand name of the future “East Balkan” Geopark seeks to make geology accessible to all. It is quite possible that someday, the new term will gain widespread popularity and will bring awareness to the geopark where it was first defined.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43436381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.191
Ralica Sabeva
The quartz-polymetallic veins from Caleta Argentina, Livingston Island, Antarctica consist of pyrite, chalcopyrite, galena, and sphalerite. Chalcopyrite is the most common ore mineral and with concentrations of Ag (average 240.51 ppm). Sphalerite contains Ag (average 50.82) and Au (average 0.31 ppm), and pyrite – Au from not detectable to 1.03 ppm (average 0.59 ppm) and Ag from not detectable to 54.33 ppm (average 32.52 ppm). Caleta Argentina, as one of the ore occurrences in Hurd Peninsula, has to be correlated with the other research area such as the Bulgarian Antarctic Base, the Bulgarian Beach, and Sally Rocks.
{"title":"Ore mineralogy and mineral chemistry of quartz-polymetallic veins in Caleta Argentina, Livingston Island, Antarctica","authors":"Ralica Sabeva","doi":"10.52215/rev.bgs.2022.83.3.191","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.191","url":null,"abstract":"The quartz-polymetallic veins from Caleta Argentina, Livingston Island, Antarctica consist of pyrite, chalcopyrite, galena, and sphalerite. Chalcopyrite is the most common ore mineral and with concentrations of Ag (average 240.51 ppm). Sphalerite contains Ag (average 50.82) and Au (average 0.31 ppm), and pyrite – Au from not detectable to 1.03 ppm (average 0.59 ppm) and Ag from not detectable to 54.33 ppm (average 32.52 ppm). Caleta Argentina, as one of the ore occurrences in Hurd Peninsula, has to be correlated with the other research area such as the Bulgarian Antarctic Base, the Bulgarian Beach, and Sally Rocks.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43383053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.141
I. Boncheva, P. Andreeva, V. Sachanski
Paleozoic (Silurian and Devonian) cherts from Western Bulgaria occur in three tectonic units: Svoge, Lyubash-Golo Bardo and Morava. The SiO2 content in these rocks varies from 76.06% to 96.02%. The silica source and depositional settings of the cherts have been interpreted based on the received geochemical major element data. The calculated Si/(Si+Fe+Al+Ca) ratio and Al–Fe–Mn diagram plotting at non-hydrothermal field suggest that most of silica in the cherts is biogenic or both biogenic and terrigenous in origin. On the other hand, all studied siliceous samples plot into the field of the continental margin sediment environments on the Fe2O3/TiO2 vs. Al2O3/(Al2O3+Fe2O3) diagram. The calculated MnO/TiO2 ratio also indicates deposition in continental shelf or slope environments.
{"title":"Geochemistry and depositional settings of Paleozoic cherts from Western Bulgaria: preliminary results","authors":"I. Boncheva, P. Andreeva, V. Sachanski","doi":"10.52215/rev.bgs.2022.83.3.141","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.141","url":null,"abstract":"Paleozoic (Silurian and Devonian) cherts from Western Bulgaria occur in three tectonic units: Svoge, Lyubash-Golo Bardo and Morava. The SiO2 content in these rocks varies from 76.06% to 96.02%. The silica source and depositional settings of the cherts have been interpreted based on the received geochemical major element data. The calculated Si/(Si+Fe+Al+Ca) ratio and Al–Fe–Mn diagram plotting at non-hydrothermal field suggest that most of silica in the cherts is biogenic or both biogenic and terrigenous in origin. On the other hand, all studied siliceous samples plot into the field of the continental margin sediment environments on the Fe2O3/TiO2 vs. Al2O3/(Al2O3+Fe2O3) diagram. The calculated MnO/TiO2 ratio also indicates deposition in continental shelf or slope environments.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48249448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.255
Marina Mitrašinović, Vesna Ristić Vakanjac, Veljko Marinović, S. Milanović, Ljiljana Vasić, D. Polomcic
The paper compares the flow regimes of the Resava River at the gauging stations of the Manasija Monastery (upper course) and the town of Svilajnac (lower course). The hydrological analysis encompasses a multiyear period of monitoring (1982–2020). The water budget and baseflow index are assessed for the catchment areas monitored by the Svilajnac station (683 km2) and the Manasija Monastery station (358k m2), considering the overall monitoring period and characteristic years. The results indicate that the specific runoff in the upper catchment is about 50% higher than that of the entire catchment. The reason is that the upper catchment is 55% karst, whereas the remainder is non-karst. The situation is similar in dry years. However, in wet years the specific runoff of the entire catchment is higher than that of the upper catchment.
{"title":"Karst aquifer impact on the formation of surface runoff: case study of the Resava River catchment, Serbia","authors":"Marina Mitrašinović, Vesna Ristić Vakanjac, Veljko Marinović, S. Milanović, Ljiljana Vasić, D. Polomcic","doi":"10.52215/rev.bgs.2022.83.3.255","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.255","url":null,"abstract":"The paper compares the flow regimes of the Resava River at the gauging stations of the Manasija Monastery (upper course) and the town of Svilajnac (lower course). The hydrological analysis encompasses a multiyear period of monitoring (1982–2020). The water budget and baseflow index are assessed for the catchment areas monitored by the Svilajnac station (683 km2) and the Manasija Monastery station (358k m2), considering the overall monitoring period and characteristic years. The results indicate that the specific runoff in the upper catchment is about 50% higher than that of the entire catchment. The reason is that the upper catchment is 55% karst, whereas the remainder is non-karst. The situation is similar in dry years. However, in wet years the specific runoff of the entire catchment is higher than that of the upper catchment.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49581268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.73
M. Dyulgerov
New age determinations by in-situ zircon and titanite LA-ICP-MS analysis for Variscan magmatic activity from Kraishte and Balkan Mts. are reported. The results confirm the presumed Variscan age of the magmatic rocks. For the Sedemte Prestola potassic granitoids, titanite dating reveal an age of 308.7±9.1 Ma. The zircon dating of potassic syenites, cropping out west of Shipka town gave less consistent results – 355±89 Ma. For potassic-alkaline syenite porphyries from the Lutskan pluton, Variscan 206Pb/238U ages cluster in 328–308 Ma interval. Zircons dating of potassic quartzdiorite porphyry from the Lutskan pluton display important inheritance with single 206Pb/238U age of 316 Ma, whereas results of titanite dating range between 350 and 315 Ma, defining poor isochrone of 301±91 Ma and MSWD of 5.6. Zircons from gabbro-diorite porphyries, cutting the Lutskan granitoids plotted on Terra-Wasserburg diagram yield Variscan age of 312±21 Ma and Concordia age of 296±4.6 Ma.
{"title":"Dating of Variscan magmatism in Kraishte and Balkan Mts","authors":"M. Dyulgerov","doi":"10.52215/rev.bgs.2022.83.3.73","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.73","url":null,"abstract":"New age determinations by in-situ zircon and titanite LA-ICP-MS analysis for Variscan magmatic activity from Kraishte and Balkan Mts. are reported. The results confirm the presumed Variscan age of the magmatic rocks. For the Sedemte Prestola potassic granitoids, titanite dating reveal an age of 308.7±9.1 Ma. The zircon dating of potassic syenites, cropping out west of Shipka town gave less consistent results – 355±89 Ma. For potassic-alkaline syenite porphyries from the Lutskan pluton, Variscan 206Pb/238U ages cluster in 328–308 Ma interval. Zircons dating of potassic quartzdiorite porphyry from the Lutskan pluton display important inheritance with single 206Pb/238U age of 316 Ma, whereas results of titanite dating range between 350 and 315 Ma, defining poor isochrone of 301±91 Ma and MSWD of 5.6. Zircons from gabbro-diorite porphyries, cutting the Lutskan granitoids plotted on Terra-Wasserburg diagram yield Variscan age of 312±21 Ma and Concordia age of 296±4.6 Ma.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49594539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.303
V. Nikolova, Dimitar Sachkov, R. Rizova
Morphometric features of the topographic surface are one of the main prerequisites (conditioning factors) for the occurrence of erosion and debris flows. The following morphometric parameters of the river Byuyukdere watershed were calculated in the current study: basin area, basin relief, basin length, relief ratio, Melton’s index, slope and stream power index. The analysis shows higher susceptibility to erosion and debris flows of the 1st and 2nd order basins (Strahler’s method). The elevated values of the stream power index indicate an intensive erosion in the lower part of the river Byuyukdere watershed, which is related to the volcanogenic-sedimentary rocks and the faulted nature of the river valley. The morphometric analysis was performed in ArcGIS Pro on the base of a 12.5 m resolution digital elevation model.
{"title":"Morphometric indicators for erosion and debris flows propagation: a case study of the river Byuyukdere watershed, northwest of Kardzhali town (Bulgaria)","authors":"V. Nikolova, Dimitar Sachkov, R. Rizova","doi":"10.52215/rev.bgs.2022.83.3.303","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.303","url":null,"abstract":"Morphometric features of the topographic surface are one of the main prerequisites (conditioning factors) for the occurrence of erosion and debris flows. The following morphometric parameters of the river Byuyukdere watershed were calculated in the current study: basin area, basin relief, basin length, relief ratio, Melton’s index, slope and stream power index. The analysis shows higher susceptibility to erosion and debris flows of the 1st and 2nd order basins (Strahler’s method). The elevated values of the stream power index indicate an intensive erosion in the lower part of the river Byuyukdere watershed, which is related to the volcanogenic-sedimentary rocks and the faulted nature of the river valley. The morphometric analysis was performed in ArcGIS Pro on the base of a 12.5 m resolution digital elevation model.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42792136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.313
Yordanka Donkova, M. Yaneva, L. Leshtakov, V. Petrova
The archaeological sites Gradishte 2 and Gradishte 3 are located along the Haemus Motorway. The area was inhabited for a long period of time – from the late Neolithic–Chalcolithic period, Early Iron Age up to late antiquity. All excavated structures such as pits, dwellings, and EIA necropolis were situated in a similar type of sediments – clayey loess. Differences between the loess in these sites are the clay content, freshness, and roundness of quartz and feldspars. They are explained by different watershed areas, variations in the source area, and weathering intensity.
{"title":"Palaeoenvironment during the Prehistoric and Ancient times in the area \u0000of the village of Gradishte, Shumen District","authors":"Yordanka Donkova, M. Yaneva, L. Leshtakov, V. Petrova","doi":"10.52215/rev.bgs.2022.83.3.313","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.313","url":null,"abstract":"The archaeological sites Gradishte 2 and Gradishte 3 are located along the Haemus Motorway. The area was inhabited for a long period of time – from the late Neolithic–Chalcolithic period, Early Iron Age up to late antiquity. All excavated structures such as pits, dwellings, and EIA necropolis were situated in a similar type of sediments – clayey loess. Differences between the loess in these sites are the clay content, freshness, and roundness of quartz and feldspars. They are explained by different watershed areas, variations in the source area, and weathering intensity.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44914661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.97
A. Hikov, Elitsa Stefanova, V. Sachanski, Z. Milakovska, Milen Stavrev, K. Kouzmanov, S. Chavdarova, S. Georgiev
The studied Silurian nodules have hard light cores and dark shells. The cores consist of quartz with disseminated zonal carbonate mineral and pyrite. Zones in the carbonate have a variable composition from Mn-containing siderite, ankerite and dolomite to mixed Fe-Mn carbonate and Fe-containing rhodochrosite. The nodule shells are composed of quartz, chlorite, sericite, goethite, Mn-Fe oxyhydroxides and siderite. Fe-Mn oxyhydroxides in the nodule shells are formed due to an alteration of the carbonate minerals and inherited their composition. The formation of the nodules with Fe- and Mn-carbonates is related to diagenetic processes under reducing conditions of low Eh and high pH values. Later, carbonate minerals were altered into Fe-Mn oxyhydroxides. These alteration changes can be related to the influence of later magmatic activity in the area. An example of this activity is the presence of an igneous bodies established on both sides of the section.
{"title":"Manganese carbonate minerals and their alteration products in Silurian metalliferous nodules from the region of Asaritsa peak, West Balkan Mountain","authors":"A. Hikov, Elitsa Stefanova, V. Sachanski, Z. Milakovska, Milen Stavrev, K. Kouzmanov, S. Chavdarova, S. Georgiev","doi":"10.52215/rev.bgs.2022.83.3.97","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.97","url":null,"abstract":"The studied Silurian nodules have hard light cores and dark shells. The cores consist of quartz with disseminated zonal carbonate mineral and pyrite. Zones in the carbonate have a variable composition from Mn-containing siderite, ankerite and dolomite to mixed Fe-Mn carbonate and Fe-containing rhodochrosite. The nodule shells are composed of quartz, chlorite, sericite, goethite, Mn-Fe oxyhydroxides and siderite. Fe-Mn oxyhydroxides in the nodule shells are formed due to an alteration of the carbonate minerals and inherited their composition. The formation of the nodules with Fe- and Mn-carbonates is related to diagenetic processes under reducing conditions of low Eh and high pH values. Later, carbonate minerals were altered into Fe-Mn oxyhydroxides. These alteration changes can be related to the influence of later magmatic activity in the area. An example of this activity is the presence of an igneous bodies established on both sides of the section.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45247906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.51
Y. Tzvetanova, I. Piroeva
Thaumasite was found in zoned calcic skarns hosted by the monzonitic rocks of the Zvezdel pluton, Eastern Rhodopes. Associated minerals are wollastonite, clinopyroxene, grossular-andradite garnets, Ti-rich garnets, plagioclase, calcite, quartz, epidote, prehnite, and chlorite. Titanite, apatite and magnetite are present as accessories. The mineral has been characterized using optical microscopy, PXRD, SEM/EDS, EPMA, and FTIR. Thaumasite forms sheaf-like and fan-shaped aggregates, which consist of acicular crystals elongated along the c axis. The IR spectrum of thaumasite is in accordance with the chemical composition and contains absorption bands in the range 3500–3291 cm–1 (O–H stretching vibrations); 1683, 1650 cm–1 (bending vibrations of H2O); 1389 cm–1 (stretching vibrations of CO32–); 1100, 1069 cm–1 (asymmetric stretching vibrations of SO42–); 882 cm–1 (symmetric bending vibration of CO32–); 768, 742, 680 cm–1 (Si–O stretching vibrations of Si(OH)6 octahedra); 670 cm–1 (bending vibrations of SO42–).
{"title":"Thaumasite in calcic skarns from the Zvezdel-Pcheloyad Pb-Zn deposit, Eastern Rhodopes, Bulgaria","authors":"Y. Tzvetanova, I. Piroeva","doi":"10.52215/rev.bgs.2022.83.3.51","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.51","url":null,"abstract":"Thaumasite was found in zoned calcic skarns hosted by the monzonitic rocks of the Zvezdel pluton, Eastern Rhodopes. Associated minerals are wollastonite, clinopyroxene, grossular-andradite garnets, Ti-rich garnets, plagioclase, calcite, quartz, epidote, prehnite, and chlorite. Titanite, apatite and magnetite are present as accessories. The mineral has been characterized using optical microscopy, PXRD, SEM/EDS, EPMA, and FTIR. Thaumasite forms sheaf-like and fan-shaped aggregates, which consist of acicular crystals elongated along the c axis. The IR spectrum of thaumasite is in accordance with the chemical composition and contains absorption bands in the range 3500–3291 cm–1 (O–H stretching vibrations); 1683, 1650 cm–1 (bending vibrations of H2O); 1389 cm–1 (stretching vibrations of CO32–); 1100, 1069 cm–1 (asymmetric stretching vibrations of SO42–); 882 cm–1 (symmetric bending vibration of CO32–); 768, 742, 680 cm–1 (Si–O stretching vibrations of Si(OH)6 octahedra); 670 cm–1 (bending vibrations of SO42–).","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45342714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.52215/rev.bgs.2022.83.3.165
M. Yaneva, Nadja Ognjanova-Rumenova, E. Koleva-Rekalova, P. Nikolov, Yordanka Donkova
New outcrops of the Konkian part of the Euxinograd Formation, located between Briz beach and Trakata beach, have been studied. The section comprises an alternation of gray calcareous clays, laminated calcareous clays and limestones, whose age is determined by mollusks and diatoms and ranges from the Konkian to the Sarmatian. The studied sediments were deposited in a shallow-marine environment with frequent fluctuations of the sea level. The fossil diatom flora is characterized by a monotonous species composition. The presence of crushed diatom valves and a relatively abundant sand fraction suggest intermittent high water dynamics. Generally, the climate was warm, with at least three dry periods, during which the alkalinity and CaCO3 content increased significantly and the living conditions of the mollusks and diatoms deteriorated.
{"title":"Bioevents at the Konkian/Sarmatian boundary (Northeastern Bulgaria) – a response to paleoclimatic changes","authors":"M. Yaneva, Nadja Ognjanova-Rumenova, E. Koleva-Rekalova, P. Nikolov, Yordanka Donkova","doi":"10.52215/rev.bgs.2022.83.3.165","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.3.165","url":null,"abstract":"New outcrops of the Konkian part of the Euxinograd Formation, located between Briz beach and Trakata beach, have been studied. The section comprises an alternation of gray calcareous clays, laminated calcareous clays and limestones, whose age is determined by mollusks and diatoms and ranges from the Konkian to the Sarmatian. The studied sediments were deposited in a shallow-marine environment with frequent fluctuations of the sea level. The fossil diatom flora is characterized by a monotonous species composition. The presence of crushed diatom valves and a relatively abundant sand fraction suggest intermittent high water dynamics. Generally, the climate was warm, with at least three dry periods, during which the alkalinity and CaCO3 content increased significantly and the living conditions of the mollusks and diatoms deteriorated.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43840141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：