Neogene Lake Basins in Southwestern Bulgaria — biostratigraphy, palaeoecology and diatom floristic interrelations

Pages: 
pp. 57-61
Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
Abstract: 

Modeling of the evolution of freshwater diatoms and the mechanism of their distribution in the Neogene lake system in Southwestern Bulgaria is accomplished for the first time. The main purpose is the determination of the major stages in the evolution of the Mio-Pliocene diatom floras developed in the graben structures in this realm. Various data were used for the realization of this purpose: palaeontological, biostratigraphical, mineralogical, petrological and sedimentological. Outcrops and core drills from Stanitsi, Beli Breg, Sofia, Chukurovo, Palakaria, Kostenets, Razlog, Simitli, Sandanski, Strumeshnitsa, Gotse Delchev, Satovcha Basins and Valkosel-Tuhovitsa depression were characterized. In total, 660 diatom species, varieties and forms have been described from these lake systems. This surprisingly high diversity is even comparable with marine biodiversity for the Eastern Paratethyan Bay on the territory of Northeastern Bulgaria (546 species, varieties and forms) during the Miocene. The oldest known lacustrine diatoms from the sediments in Southwestern Bulgaria are Middle Miocene in age (Simitli Basin — Simitli Formation), the youngest — Early Pliocene. Three major stages in the evolution and distribution of centric diatom genera can be distinguished during Middle Miocene-Pliocene. Diatom analyses, complemented by structural and geodynamic investigations could demonstrate the impact of different palaeoenvironmental factors on the development of the diatom flora. We found that the process of nutrient levels, the salt content, temperature and the changes in the depth of the lake correlated significantly with patterns in the diatom assemblages, based on complex of lithostratigraphic and biostratigraphic investigation, as well as different statistical techniques. The inference model of Sofia Basin could be useful in describing the colonization of diatoms in the lacustrine basins on the territory of Southwestern Bulgaria.

Н. Огнянова-Руменова, М. Янева, Г. Николов Неогеновые озерные бассейны в Юго-Западной Болгарии биостратиграфия, палеоэкология и взаимоотношения диатомей. Впервые сделано восстановление эволюции пресноводных диатомей и механизма их распределения в неогеновой озерной системе Юго-Западной Болгарии. Основная цель работы — определение основных этапов в эволюции мио-плиоценовых диатомейных флористических ассоциаций, развивавшихся в грабеновых структурах региона. Для осуществелния этой цели использовались палеонтологические, биостратиграфические, минералогические, петрологические и седиментологические данные. Приведена характеристика материала из обнажений и буровых скважин около сел Станянцы, Бели бряг и Чукурово, района Софии, Палакарийской долины, Костенецкого района, районов около городов Разлог, Симитли и Сандански, Струмешницкой долины, г. Гоце Делчев, Сатовчанского бассейна и Вылкосел-Туховицской депрессии. Сделано описание 660 диатомейных видов, разновидностей и форм. Это удивительное разнообразие сопоставимо с морским биологическим разнообразием восточного Паратетисского залива на территории Северо-Восточной Болгарии во время миоцена (546 видов, разновидностей и форм). Самые ранние озерные диатомеи Юго-Западной Болгарии установлены в среднемиоценовых породах Симитлийского бассейна (Симитлийская свита), а возраст самых молодых — раннеплиоценовый. В эволюции и распределении установленных центрических видов среднимиоценовых — плиоценовых диатомей можно выделить три основных этапа. Анализ диатомей, дополненный структурными и геодинамическими исследованиями может выявить влияние разных факторов палеоэкологической обстановки на развитие диатомейной флоры. Авторами установлено, что питательность среды, уровень солености бассейнов, температура и изменения глубин озерного бассейна в значительной степени коррелируются с особенностями диатомейных ассоциаций, установленных на основании литостратиграфических и биостратиграфических исследований и в результате приложения разных статистических методов. Предложенная заключительная модель Софийского бассейна может оказаться полезной при описании колонизации диатомей в озерных бассейнах Юго-Западной Болгарии.

Keywords: 

diatom biostratigraphy, palaeolimnology, Middle Miocene-Early Pliocene, Southwestern Bulgaria

VOLUME 36 (3-4)/December 2007

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

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, Bulgaria, 1113 Sofia, Acad. G. Bonchev Str., Bl. 24

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

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

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Instituto Andaluz de Ciencias de la Tierra, CSIC, Granada, Spain
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University of Granada, Granada, Spain
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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University of Granada, Granada, Spain
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia

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

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia

Geological Institute, Bulgarian academy of Scienses, 1113 Sofia, 24 G. Bonchev Str.
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Geological Institute, Bulgarian academy of Scienses, 1113 Sofia, 24 G. Bonchev Str.

Sofia University “St. Kliment Ohridsky”, 1000 Sofia, 15 Tsar Osvoboditel Blvd.
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Geological Institute Bulgarian Academy of Sciences, 1113 Sofia, 24 G. Bonchev Str.
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Geological Institute Bulgarian Academy of Sciences, 1113 Sofia, 24 G. Bonchev Str.
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Ministry of Environment and Water, 1000 Sofia, 22 Maria Louisa Blvd.

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, 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

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Bulgarian Academy of Sciences, Geological Institute, Acad. G. Bonchev St. Bl. 24, 1113 Sofia, Bulgaria
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Middle East Technical University, Department of Geological Engineering, 06531 Ankara, Turkey
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General Directorate of Mineral Research and Exploration, Department of Geological Research, 06520 Ankara, Turkey
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General Directorate of Mineral Research and Exploration, Department of Geological Research, 06520 Ankara, Turkey

Geophysical Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia

Geological Institute, Bulgarian Academy of Sciences
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Geological Institute, Bulgarian Academy of Sciences
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Geological Institute, Bulgarian Academy of Sciences