Inoceramid bivalves and calcareous nannofossils from the Coniacian of the Western Srednogorie Unit (Western Bulgaria)

Pages: 
pp. 87-96
Faculty of Geology and Geography, Department of Geology, Palaeontology and Fossil Fuels, Sofia University “St Kliment Ohridski, 15 Tsar Osvoboditel Blvd, 1504 Sofia, Bulgaria
Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
Abstract: 

The inoceramid fauna and the calcareous nannoflora of the Coniacian in two sections (Rebro and Kondel Hill) in the Western Srednogorie Unit (Western Bulgaria) have been investigated. Both of the studied sedimentary successions yielded well-preserved inoceramid bivalves. Although the calcareous nannofossil assemblages exhibit poor to very poor preservation, they are reasonably taxonomically diverse and allowed biostratigraphic interpretations to be made. In section Rebro, where the sediments of the Izvor Formation are exposed, the inoceramid fauna indicates the presence of the lower Coniacian Cremnoceramus crassus inconstans and Cremnoceramus crassus crassus/Cremnoceramus deformis deformis inoceramid zones. Based on the consistent occurrence of Broinsonia parca subsp. expansa and the absence of Micula staurophora, the sediments have been assigned to nannofossil subzone UC9c. In section Kondel Hill, the rocks of the Izvor and Melove formations crop out. Only the lowermost ~5 m of the Melove Formation yielded inoceramids, which indicate the presence of the lower Coniacian Cremnoceramus crassus crassus/Cremnoceramus deformis deformis inoceramid Zone. The nannofossil assemblages indicate the presence of nannofossil zones UC9 (in the Izvor and Melove formations) and UC10 (in the Melove Formation), which extend from the upper Turonian (pars.) to the upper Coniacian (pars.). Base Micula staurophora/base UC10 could not be correlated with inoceramid data, however, because it was detected above the inoceramid-bearing strata.

Keywords: 

inoceramid bivalves, calcareous nannofossils, biostratigraphy, Coniacian, Western Srednogorie Unit, Western Bulgaria

VOLUME 46 (2)/November 2017 125th Anniversary of Acad. Strashimir Dimitrov; 70th Anniversary of the Geological Institute, Bulgarian Academy of Sciences

University of Mining and Geology, Department of Geology and Geoinformatics, Studentski Grad, Prof. Boyan Kamenov Str., 1700 Sofia, Bulgaria; Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Ellatzite-Med PLC, 2086 Mirkovo, Sofia District, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia
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Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute “Strashimir Dimitrov”, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Department of Geology, Palaeontology and Fossil Fuels, Sofia University, 15 Tzar Osvoboditel Blvd, 1000 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Polish Geological Institute – National Research Institute, Rakowiecka 4, 00-975 Warszawa, Poland
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Comenius University, Faculty of Natural Sciences, Department of Geology and Palaeontology, Mlynská dolina G–229, Ilkovičova 6, SK-84215 Bratislava, Slovak Republic
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Polish Geological Institute – National Research Institute, Rakowiecka 4, 00-975 Warszawa, Poland
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Institute of Geology, Academy of Sciences of the Czech Republic, v.v.l., Rozvojová, 269,165 000 Praha 6, Czech Republic

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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University of Sofia “St Kliment Ohridski”, Faculty of History, Department of Archaeology, 15 Tsar Osvoboditel Blvd, 1000 Sofia, Bulgaria
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University of Sofia “St Kliment Ohridski”, Faculty of History, Department of Archaeology, 15 Tsar Osvoboditel Blvd, 1000 Sofia, Bulgaria
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National Institute of Archaeology and Museum, Bulgarian Academy of Sciences, Department of Prehistory, 2 Saborna Str., 1000 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 24, 1113 Sofia, Bulgaria
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National Institute of Meteorology and Hydrology, 66 Tsarigradsko Shose Blvd, 1784 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Faculty of Geology and Geography, Department of Geology, Palaeontology and Fossil Fuels, Sofia University “St Kliment Ohridski, 15 Tsar Osvoboditel Blvd, 1504 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

University of Mining and Geology, Prof. B. Kamenov Str., Sofia, 1700. Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria
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University of Mining and Geology, Prof. B. Kamenov Str., Sofia, 1700. Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 24, Sofia 1113, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Austrian Institute of Technology, Center for Energy, Konrad-Lorenz-Str. 24, 3430 Tulln, Austria
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Austrian Institute of Technology, Center for Energy, Konrad-Lorenz-Str. 24, 3430 Tulln, Austria
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Austrian Institute of Technology, Center for Energy, Konrad-Lorenz-Str. 24, 3430 Tulln, Austria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev, Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev, Bl. 24, 1113 Sofia, Bulgaria; Institute of Geochemistry and Petrology, ETH, 8092 Zurich, Switzerland
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Institute of Geochemistry and Petrology, ETH, 8092 Zurich, Switzerland
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev, Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev, Bl. 24, 1113 Sofia, Bulgaria