Radioisotopic data and geodynamic interpretations in the eastern part of the Balkan Peninsula

Pages: 
pp. 21-26
Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev str. Bl. 24
Abstract: 

Results of radiogeochronological studies on the igeous and metamorphic rock complexes can be effectively interpreted only when taking into account the possibilities and limitations of each method applied.
   Igneous rocks are comparatively easily dated when have not suffered superimposed thermal or tectonothermal (metamorphic) events after their cooling. Concordant ages are usually obtained using the Rb-Sr, U-Pb and K-Ar methods. The Ar-Ar method may be crucial for understanding the cooling history. U-Pb dating of zircon cores may supply information about the source rocks, and initial Rb-Sr ratios and Sm- Nd data are important for petrogenetic interpretations.
   When the igneous body has been subjected to post-intrusion tectonothermal events, its origin and evolution may be elucidated only with the aid of a complex of methods. The age of the intrusion may be obtained using isochrone methods: Rb-Sr whole-rock isochrone (the mineral isochrone reflect the time of superimposed metamorphism) and U-Pb zircon ages using the concordia-discordia diagram. In the second case, the upper concordia/discordia intercept is related to the intrusion age whereas the lower intercept gives the age of the superimposed metamorphism. In the most general case, K-Ar dates would be "mixed data" situated between the age of cooling and the time of superimposed metamorphism, and in case of full radiogenic Ar loss during the superimposed event, would date the latter. In such a case, the Ar-Ar method will supply information about the cooling history of this last tectonothermal event.
   A single metamorphic event (or cycle) imposed over a sedimentary or volcano-sedimentary sequence would result in concordant ages obtained by different isotopic methods. Considerable difficulties arise when trying to date polymetamorphic complexes with a long and controversial history. Unfortunately, such is the case with most of the polymetamorphic rocks exposed in the central parts of the Balkan Peninsula.
   The present overview aims to compare the information obtained during the last years when extensive new data have been published. The reference list contains (due to the very limited space) only a selected fraction of the various sources used. The author apologizes for the forceful omission of many valuable sources that will be fully cited in a following extended publication.

VOLUME 32 (2-4)/December 2002 110th Anniversary of Acad. Prof. Strashimir Dimitrov; XVII Congress of the Carpathian-Balkan Geological Association

Geologica Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 24, 1113 Sofia, Bulgaria

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

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev str. Bl. 24

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

Geological Institute, Bulgarian Academy of Sciences,Sofia 1113, Bulgaria, Acad. G. Bonchev str, bl. 24
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Geological Institute, Bulgarian Academy of Sciences,Sofia 1113, Bulgaria, Acad. G. Bonchev str, bl. 24
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Earth Science Section of the Uviversity of Geneva, 13, rue des Maraîchers, 1211 Geneva 4, Switzerland
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Earth Science Section of the Uviversity of Geneva, 13, rue des Maraîchers, 1211 Geneva 4, Switzerland

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, 1113 Sofia, Bulgaria

Geological Institute BAS, Acad. G. Bonchev Str., Bl. 24 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
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Sofia University "Sv. Kliment Ohridski", 1504 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Sofia University "Sv. Kliment Ohridski", Tsar Osvobodilel Blvd, 15, 1000 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia

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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University of Mining and Geology "Sv. Ivan Rilski", 1700, Sofia

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

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Institute of Geochemistry, Siberian branch of the Russian Academy of Sciences, P.O.B. 4019, 664033 Irkutsk
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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 Sciences, Sofia, 1113
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Geological Institute, Bulgarian Academy of Sciences, Sofia, 1113
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Geological Institute, Bulgarian Academy of Sciences, Sofia, 1113
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Geological Institute, Bulgarian Academy of Sciences, Sofia, 1113
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Geological Institute, Bulgarian Academy of Sciences, Sofia, 1113
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Geological Institute, Bulgarian Academy of Sciences, Sofia, 1113

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia

Geological Institute, Bulgarian Academy of Sciences, Sofia, 1113

Geological Institute, Bulgarian Academy of Sciences

Geological Institute, BAS, Acad. G. Bonchev Street Bl. 24, 1113 Sofia, Bulgaria

Geological Institute of BAS, 24 Acad. G. Bonchev Sir., BG - 1113 Sofia
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Geological Institute of BAS, 24 Acad. G. Bonchev Sir., BG - 1113 Sofia
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Geological Institute of BAS, 24 Acad. G. Bonchev Sir., BG - 1113 Sofia

Geological Institute at the Bulgarian Academy of Sciences, Acad. G. Bonchev Str., 1113 Sofia, Bulgaria
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Geological Institute at the Bulgarian Academy of Sciences, Acad. G. Bonchev Str., 1113 Sofia, Bulgaria
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Geological Institute at the Bulgarian Academy of Sciences, Acad. G. Bonchev Str., 1113 Sofia, Bulgaria

University of Mining and Geology, Studentski grad, Sofia, 1100, Bulgaria
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Geological Institute of Romania, Caransebes Str. No 1, Bucharest, RO-78344, Romania
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University of Belgrade, Dusina 7, Belgrad, 11000, Yugoslavia
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Geological Institute of Romania, Caransebes Str. No 1, Bucharest, RO-78344, Romania

Geological Institute at Bulgarian Academy of Sciences, Sofia 1113

Sofia University "Sv. Kl. Ohridski", Department of Geology and Palaeontology, 1504 Sofia