Pub Date : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.223
A. Vasilev, P. Petsinski, Raina Hristova, Rosica Pehlivanova
This work presents results from the first purposeful in situ temperature measurements in seafloor sediments above a scalable gas hydrate deposit in the deep-water Danube paleodelta. Temperatures and temperature gradients with accuracy 5 mK and sensitivity 1 mK are measured with 3 MTL loggers with clamps (Antares GmbH) welded to a gravity corer with length of 6 m, outer diameter of 130 mm and weight ~300 kg. During the cruise MN249 on board of the Romanian R/V Mare Nigrum 10-20/10/2023, the gravity corer was deployed on 23 stations with successful temperature measurements and >3 m sediments lifting on 11 stations. Temperature gradients above the gas hydrate deposit (BSR area) are in ~20–50 mK/m when the background is ~30 mK/m. Additional data needed to determine the effects from the 2 main factors formatting temperature gradients – gas hydrate masses and sedimentation rates.
{"title":"Heat flow over a gas hydrate deposit in the Danube paleodelta: cruise MN249, 10-20/09/2023","authors":"A. Vasilev, P. Petsinski, Raina Hristova, Rosica Pehlivanova","doi":"10.52215/rev.bgs.2023.84.3.223","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.223","url":null,"abstract":"This work presents results from the first purposeful in situ temperature measurements in seafloor sediments above a scalable gas hydrate deposit in the deep-water Danube paleodelta. Temperatures and temperature gradients with accuracy 5 mK and sensitivity 1 mK are measured with 3 MTL loggers with clamps (Antares GmbH) welded to a gravity corer with length of 6 m, outer diameter of 130 mm and weight ~300 kg. During the cruise MN249 on board of the Romanian R/V Mare Nigrum 10-20/10/2023, the gravity corer was deployed on 23 stations with successful temperature measurements and >3 m sediments lifting on 11 stations. Temperature gradients above the gas hydrate deposit (BSR area) are in ~20–50 mK/m when the background is ~30 mK/m. Additional data needed to determine the effects from the 2 main factors formatting temperature gradients – gas hydrate masses and sedimentation rates.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139192126","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.129
Z. Milakovska, A. Hikov, V. Stoyanova, I. Peytcheva, Tomasz Abramowski
The concentrations of Fe, Mn, Co, Cd, Zn, Cu, Mo, and As were registered in broad intervals and are elevated compared to the mean values for the ocean water. Vertical distributions of the element concentrations in the pore waters along four sediment cores show distinct differences, mainly for the elements Fe, Mn, Cu, and Zn. Bioturbation activities developed in the depth interval 7–15 cm could be a probable reason for the variation trends. The distributions for the elements As, Cd, Co and Zn are conservative type and the patterns for the Mo and Ni – scavenged type. The obtained pore water profiles are similar to the distribution trends for areas in the Eastern Equatorial Pacific and show different patterns from the pore waters from the Western Pacific.
{"title":"Trace element characteristics of pore water from the deep-sea sediments of the Interoceanmetal exploration area in the Clarion-Clipperton Fracture Zone, NE Pacific","authors":"Z. Milakovska, A. Hikov, V. Stoyanova, I. Peytcheva, Tomasz Abramowski","doi":"10.52215/rev.bgs.2023.84.3.129","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.129","url":null,"abstract":"The concentrations of Fe, Mn, Co, Cd, Zn, Cu, Mo, and As were registered in broad intervals and are elevated compared to the mean values for the ocean water. Vertical distributions of the element concentrations in the pore waters along four sediment cores show distinct differences, mainly for the elements Fe, Mn, Cu, and Zn. Bioturbation activities developed in the depth interval 7–15 cm could be a probable reason for the variation trends. The distributions for the elements As, Cd, Co and Zn are conservative type and the patterns for the Mo and Ni – scavenged type. The obtained pore water profiles are similar to the distribution trends for areas in the Eastern Equatorial Pacific and show different patterns from the pore waters from the Western Pacific.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139193261","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.125
Z. Milakovska, Maya Stefanova, G. Vladislavov, Millena Vetseva
A sequence of carbonaceous mudstones interlayering three lignite seams is characterized by geochemical proxies. The core samples studied came from a borehole drilled in Trojanovo-3 Mine of Maritsa Iztok Basin. The n-alkane molecular composition is dominated by the > C29 long-chain homologues, with a strong “odd” over “even” homologue predominance. In addition to, the prevailing smooth signature of n-alkane distribution attests for one major organic matter source – land-derived higher plants. The sesqui- and di-terpenoid assemblage specifies the prevalence of Cupressaceae, Taxodiaceae, and Podocarpaceae species in the coal-forming mire. The lupane-type triterpenoids registered are a sign for Betulaceae family presence. Biomarkers for herb, macrophyte and algal/bacterial contribution are also recognizable.
{"title":"Geochemical study of the organic matter from the southern part of the Maritsa Iztok Basin","authors":"Z. Milakovska, Maya Stefanova, G. Vladislavov, Millena Vetseva","doi":"10.52215/rev.bgs.2023.84.3.125","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.125","url":null,"abstract":"A sequence of carbonaceous mudstones interlayering three lignite seams is characterized by geochemical proxies. The core samples studied came from a borehole drilled in Trojanovo-3 Mine of Maritsa Iztok Basin. The n-alkane molecular composition is dominated by the > C29 long-chain homologues, with a strong “odd” over “even” homologue predominance. In addition to, the prevailing smooth signature of n-alkane distribution attests for one major organic matter source – land-derived higher plants. The sesqui- and di-terpenoid assemblage specifies the prevalence of Cupressaceae, Taxodiaceae, and Podocarpaceae species in the coal-forming mire. The lupane-type triterpenoids registered are a sign for Betulaceae family presence. Biomarkers for herb, macrophyte and algal/bacterial contribution are also recognizable.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139195237","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.227
Stefan Velev
Porphyry ore deposits are the source of much of the copper, molybdenum, gold and silver. Porphyry hydrothermal systems typically form in magmatic arcs above subduction zones. In this article, some key factors that may be involved in the formation of the Pishtene porphyry deposit in Western Srednogorie are outlined. The first process is the generation of magma in sub-arc mantle and enrichment of metals, water and other fluids. Next stage is а cyclic crystal fractionation in deep crustal magma chamber. There are a lot of other factors, such as a sulphide saturation, metal partitioning, precipitation of ore minerals, magmatic-hydrothermal evolution, erosional and weathering processes, but they are not discussed in this study.
{"title":"Tectono-magmatic factors for porphyry Cu-(Mo-Au) deposits formation: A case study from Pishtene ore deposit, Western Srednogorie, Bulgaria","authors":"Stefan Velev","doi":"10.52215/rev.bgs.2023.84.3.227","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.227","url":null,"abstract":"Porphyry ore deposits are the source of much of the copper, molybdenum, gold and silver. Porphyry hydrothermal systems typically form in magmatic arcs above subduction zones. In this article, some key factors that may be involved in the formation of the Pishtene porphyry deposit in Western Srednogorie are outlined. The first process is the generation of magma in sub-arc mantle and enrichment of metals, water and other fluids. Next stage is а cyclic crystal fractionation in deep crustal magma chamber. There are a lot of other factors, such as a sulphide saturation, metal partitioning, precipitation of ore minerals, magmatic-hydrothermal evolution, erosional and weathering processes, but they are not discussed in this study.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139195328","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.169
V. Bozukov, D. Ivanov, Ognyan Todorov
New data from the middle Miocene Satovcha paleoflora (SW Bulgaria) are presented. The three taxa studied here, which belong to the Division Pinophyta are defined on the basis of fossil disseminules. Cephalotaxus aff. fortunei was determined by an aril impression. Picea aff. shrenkiana and Pinus aff. mugo are identified by winged seed impressions.
{"title":"New carpological data from the middle Miocene Satovcha paleoflora (SW Bulgaria)","authors":"V. Bozukov, D. Ivanov, Ognyan Todorov","doi":"10.52215/rev.bgs.2023.84.3.169","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.169","url":null,"abstract":"New data from the middle Miocene Satovcha paleoflora (SW Bulgaria) are presented. The three taxa studied here, which belong to the Division Pinophyta are defined on the basis of fossil disseminules. Cephalotaxus aff. fortunei was determined by an aril impression. Picea aff. shrenkiana and Pinus aff. mugo are identified by winged seed impressions.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139196023","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.263
Antoniya Arabadzhieva, Aglaida Toteva
Urbanisation poses significant challenges to a water resource management, especially in areas where water demand is increasing. This study focuses on the impact of the urban environment on surface and groundwater recharge in Sofia, Bulgaria, using a geographic information system (GIS) approach. The study integrates geospatial data and land use analysis to assess surface and groundwater recharge in an urban environment. The results reveal the complex interplay between urban development and water recharge, providing insight into areas experiencing stress and potential opportunities for sustainable water management. The GIS-based analysis improves understanding of the city‘s hydrological and hydrogeological system and provides information about informed decision-making on water resource sustainability in the face of increasing urbanization.
{"title":"Assessing the impact of urban environments on surface and groundwater recharge in Sofia, Bulgaria: A GIS-based analysis","authors":"Antoniya Arabadzhieva, Aglaida Toteva","doi":"10.52215/rev.bgs.2023.84.3.263","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.263","url":null,"abstract":"Urbanisation poses significant challenges to a water resource management, especially in areas where water demand is increasing. This study focuses on the impact of the urban environment on surface and groundwater recharge in Sofia, Bulgaria, using a geographic information system (GIS) approach. The study integrates geospatial data and land use analysis to assess surface and groundwater recharge in an urban environment. The results reveal the complex interplay between urban development and water recharge, providing insight into areas experiencing stress and potential opportunities for sustainable water management. The GIS-based analysis improves understanding of the city‘s hydrological and hydrogeological system and provides information about informed decision-making on water resource sustainability in the face of increasing urbanization.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139188225","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.271
Stefan Frangov, G. Frangov
The investigated landslide occurred in December 2021 on a steep river-valley slope in the southwestern part of the Pirin National Park. It has a typical circular shape with approximate dimensions: width of 20 m, length of 15 m and depth up to 4 m. The sliding involves mainly the soil-rock mass of the road embankment. The landslide affects a forest road and threatens the hydraulic canal “Syrchaliytsa” of the “Sandanska Bistritsa” cascade. The study is based on an on-site inspection and geotechnical mapping, its analysis and interpretation, aided by available archival and published data, and the authors’ personal experience of similar sites in the area and other parts of the country. The main objectives are to establish the engineering-geological conditions of the terrain, assess the main factors defining the landslide stability and develop a conceptual solution for its strengthening.
{"title":"Emergency stabilization of a landslide in Pirin National Park","authors":"Stefan Frangov, G. Frangov","doi":"10.52215/rev.bgs.2023.84.3.271","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.271","url":null,"abstract":"The investigated landslide occurred in December 2021 on a steep river-valley slope in the southwestern part of the Pirin National Park. It has a typical circular shape with approximate dimensions: width of 20 m, length of 15 m and depth up to 4 m. The sliding involves mainly the soil-rock mass of the road embankment. The landslide affects a forest road and threatens the hydraulic canal “Syrchaliytsa” of the “Sandanska Bistritsa” cascade. The study is based on an on-site inspection and geotechnical mapping, its analysis and interpretation, aided by available archival and published data, and the authors’ personal experience of similar sites in the area and other parts of the country. The main objectives are to establish the engineering-geological conditions of the terrain, assess the main factors defining the landslide stability and develop a conceptual solution for its strengthening.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139188296","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.303
Hristina Petrova, Katarzyna Wątor, Piotr Rusiniak, B. Vakanjac, Vesna Ristić Vakanjac, E. Kmiecik
Regarding the aspect of mineral, thermo-mineral, and thermal waters, on the territory of the Republic of North Macedonia, there are 65 registered locations, of which 8 are categorized as spas. This includes the Kežovica spa, also known as the Štipska spa. In the vicinity of Kežovica Spa is the thermo-mineral L’Dži spring with mineralization around 1.3 g/L and the water temperature at the time of sampling was 50.1°C. Spring L’Dži is generated by a fault structure and is linked to a granite massif of Mesozoic age. These are alkaline waters (pH=8.3) and the hydrochemical type is chloride-sodium. Regarding the trace elements, the water of the L’Dži spring contains a large amount of boron and silica. Water also contains an increased content of arsenic (200 µg/L) and tungsten (169 µg/L). Elevated concentrations of As and W are characteristic of alkaline thermal waters in reducing conditions. Often elevated concentrations of Mo are accompanied by elevated concentrations of As and W, which is also the case.
{"title":"A contribution to the understanding of hydrochemical properties of thermo-mineral water on the L’dži locality (eastern part of North Macedonia)","authors":"Hristina Petrova, Katarzyna Wątor, Piotr Rusiniak, B. Vakanjac, Vesna Ristić Vakanjac, E. Kmiecik","doi":"10.52215/rev.bgs.2023.84.3.303","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.303","url":null,"abstract":"Regarding the aspect of mineral, thermo-mineral, and thermal waters, on the territory of the Republic of North Macedonia, there are 65 registered locations, of which 8 are categorized as spas. This includes the Kežovica spa, also known as the Štipska spa. In the vicinity of Kežovica Spa is the thermo-mineral L’Dži spring with mineralization around 1.3 g/L and the water temperature at the time of sampling was 50.1°C. Spring L’Dži is generated by a fault structure and is linked to a granite massif of Mesozoic age. These are alkaline waters (pH=8.3) and the hydrochemical type is chloride-sodium. Regarding the trace elements, the water of the L’Dži spring contains a large amount of boron and silica. Water also contains an increased content of arsenic (200 µg/L) and tungsten (169 µg/L). Elevated concentrations of As and W are characteristic of alkaline thermal waters in reducing conditions. Often elevated concentrations of Mo are accompanied by elevated concentrations of As and W, which is also the case.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139189641","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.113
Evgenia Kozhoukharova
Geotribometamorphism means a process of destructive-constructive changes of the rocks in the seismotectonic zones in the Earth’s crust. Due to the friction between rock blocks and layers, kinetic energy is generated, which deforms and destroys the rocks until mylonitization and melting in an environment of high temperature and pressure. Subsequently, the disintegrated material recrystallized into new high-pressure rocks such as eclogites, garnet lherzolites, phengite and kyanite schists and calciphyres. These rocks mark paleoseismic zones and events that occurred during the Precambrian and Phanerozoic.
{"title":"Geotribometamorphism in seismic zones of the Earth’s crust","authors":"Evgenia Kozhoukharova","doi":"10.52215/rev.bgs.2023.84.3.113","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.113","url":null,"abstract":"Geotribometamorphism means a process of destructive-constructive changes of the rocks in the seismotectonic zones in the Earth’s crust. Due to the friction between rock blocks and layers, kinetic energy is generated, which deforms and destroys the rocks until mylonitization and melting in an environment of high temperature and pressure. Subsequently, the disintegrated material recrystallized into new high-pressure rocks such as eclogites, garnet lherzolites, phengite and kyanite schists and calciphyres. These rocks mark paleoseismic zones and events that occurred during the Precambrian and Phanerozoic.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190292","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 : 2023-12-01DOI: 10.52215/rev.bgs.2023.84.3.173
Georgi Granchovski, A. Hikov
Three sedimentary sections (Dalgi Rid, Milkova Cheshma and Toplika), containing Mn-bearing nodules, of the Mirkovo Formation in the Central Srednogorie tectonic unit have been investigated for their calcareous nannofossil content. The assemblages are very poorly preserved, depleted and relatively low in taxonomic diversity. The most abundant taxa are Watznaueria barnesiae, Eiffellithus eximius, Helicolithus anceps, Micula staurophora and Lucianorhabdus cayeuxii. Additionally, Lithastrinus grillii was detected in the section Toplika. Based on the nannofossil data, the sediments at Dalgi Rid and Milkova Cheshma have been referred to the middle–late Coniacian, whereas those at Toplika have been dated as late Coniacian–early(?) Santonian. These data indicate that the formation of the Mn-bearing nodules in the studied successions is time-transgressive.
{"title":"Calcareous nannofossils from the middle Coniacian–Santonian in the Mirkovo Formation, Central Srednogorie tectonic unit (central South Bulgaria)","authors":"Georgi Granchovski, A. Hikov","doi":"10.52215/rev.bgs.2023.84.3.173","DOIUrl":"https://doi.org/10.52215/rev.bgs.2023.84.3.173","url":null,"abstract":"Three sedimentary sections (Dalgi Rid, Milkova Cheshma and Toplika), containing Mn-bearing nodules, of the Mirkovo Formation in the Central Srednogorie tectonic unit have been investigated for their calcareous nannofossil content. The assemblages are very poorly preserved, depleted and relatively low in taxonomic diversity. The most abundant taxa are Watznaueria barnesiae, Eiffellithus eximius, Helicolithus anceps, Micula staurophora and Lucianorhabdus cayeuxii. Additionally, Lithastrinus grillii was detected in the section Toplika. Based on the nannofossil data, the sediments at Dalgi Rid and Milkova Cheshma have been referred to the middle–late Coniacian, whereas those at Toplika have been dated as late Coniacian–early(?) Santonian. These data indicate that the formation of the Mn-bearing nodules in the studied successions is time-transgressive.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139192954","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}
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