Structure and Alpine evolution of Bulgaria

Dabovski, Christo; Boyanov, Ivan; Khrischev, Khrischo; Николов, Тодор; Sapunov, Ivo; Yanev, Yotzo; Zagorchev, Ivan

doi:10.52321/geolbalc.32.2-4.9

Cited by 51 publications

(24 citation statements)

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“…from the end of Permian or the beginning of Middle Triassic (Gochev, 1991) when the passive continental boundary of the Paleomoesian carbonate platform developed. Triassic sediments therein have been affected by the Early Cimmerian folding and thrusting (Dabovski et al, 2002). According to Gochev (1991) the Early Cimmerian orogen has started to form during Early Triassic but developed mainly during Middle Triassic.…”

Section: Discussionmentioning

confidence: 99%

Petrology, geochemistry and age dating of Skrut granitoids – new evidence for Early Triassic magmatism in Belasitsa Mountain (SW Bulgaria)

Zidarov¹,

Tarassova²,

Peytcheva³

et al. 2007

GeolBalc

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The Skrut granitoids crop out in the western part of Belasitsa Mountain in SW Bulgaria. They are intruded in biotite gneisses and mica schists, building up together a complex nappe structure in the frame of the Serbo-Macedonian Massif (SMM). Main rock forming minerals in the Skrut granitoids are plagioclase, potassium feldspar, quartz, and biotite and accessories are apatite, allanite, epidote, zircon, titanite and garnet. These granitoids have undergone processes of dynamic metamorphism and non-uniform hydrothermal alteration. In respect to K2O content they belong to the high potassium calc-alkaline magmatic series while according to the ASI coefficient they are related to the weakly per-aluminium granitoids. The magma is enriched in water and REE. Probably, its crystallization has proceeded at pressure of 11 to 11.5 kbar (presence of magmatic epidote) and temperature of 800 to 600°C. The positive ε-Hf values of zircon crystals (from +0.4 to +3.5) propose mixed crust-mantle magma source whereas calc-alkaline characteristics and discrimination diagrams propose a volcanic-arc/continental margin or postcollisional environment of the magma generation. The age of the granitoids is determined by conventional U-Pb method on zircons as 248.85±0.70 Ma. The regression line obtained by the Rb–Sr isotope analyses on whole rock samples yield an age of 167.3±8.1 Ma, which is interpreted as a mixing line, probably influenced also by overprinted events. The new data suggest formation of the Skrut granitoids during the Early Triassic as a result of Late Variscan event in extensional conditions and block dismembering (rifting?). The post-metamorphic intrusion of the granitoids defines the high grade metamorphism in Belasitsa Mountain as pre-Triassic in age.

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Section: Discussionmentioning

confidence: 99%

Petrology, geochemistry and age dating of Skrut granitoids – new evidence for Early Triassic magmatism in Belasitsa Mountain (SW Bulgaria)

Zidarov¹,

Tarassova²,

Peytcheva³

et al. 2007

GeolBalc

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“…It has been greatly influenced by the concept of Bončev (1965a, b) about the role of the transversal cryptolineaments (Etropole and Tvurditsa "lines"), and the megablocs (West-Bulgarian, Central-Bulgarian and East-Bulgarian) bounded by them. A more detailed study of the stratigraphy and palaeogeography of SW Bulgaria and the adjacent territories has shown (s. Boyanov et al, 1989;Zagorchev, 2001;Dabovski et al, 2002) that major faults used as boundaries for the transversal zoning are in fact much younger then the sedimentation zones, and that the positioning of the latter is related to the com-plex evolution of the margin between the Tethys Ocean and the Eurasian continent. However, the transversal zoning of the Kraishtides may be considered as a valid one in respect of the overall structure of the Strouma (Kraishtide) fault belt (lineament) in Cenozoic times as far as the bounding fault zones (Danube and Nish strike-slip faults; Kyustendil fault; Brezhani fault zone /Kroupnik fault/; Middle-Mesta fault zone /South Belasitsa fault/) are indeed major Palaeogene to Recent faults with considerable importance for the fault tectonics and the seismicity of the Balkan Peninsula.…”

Section: Boundaries Of the Kraishtidesmentioning

confidence: 99%

“…For the aims of this study, we need to emphasize only on some geological phenomena crucial for understanding the geological structure and its formation and evolution, for to be able to distinguish between sedimentation zones, tectonic units and geodynamic zones/units in space and time. The approach to Alpine geodynamics will be that already used by Boyanov et al (1989) and Dabovski et al (2002).…”

Section: Main Lines Of the Geological Structure Of Sw Bulgariamentioning

confidence: 99%

“…However, the latest Eocene -Early Oligocene ingression that formed the Padesh-Piyanets shallow gulf is clearly oblique to the "Kraishtides", penetrating from the Southwest (Tikvesh and Ovchepolje) to Northest. Observations over a wider region show that both the Palaeogene (Eocene -Oligocene) sedimentation and volcanism (Harkovska et al, 1989;Dabovski et al, 1991) were located within a large arc South of the Srednogorie zone, and related to the extensional collapse of the Srednogorie Late Cretaceous orogen, and mostly to the collapse of the "plateau" situated to the South (Morava-Rhodope zone - Dabovski et al, 2002).…”

Section: Alpine Sedimentationmentioning

confidence: 99%

“…The present author published two short reviews on the history, nature and content of this notion in papers centered on the Alpine structure of SW Bulgaria (Çàãîð÷åâ, 1984;Zagorchev, 1992). However, during the work on the geodynamic and tectonic bases (Zagorchev, 2001;Dabovski et al, 2002) of the collective work on a modern "Geology of Bulgaria" the colleagues insisted on several occasions to have in hands a more thorough and well-argumented discussion on the matter. The same questions have been raised by colleagues from Macedonia, Romania and Serbia during the last two congresses of the Carpathian-Balkan Geological Association held in Vienna and Bratislava.…”

Section: Introductionmentioning

confidence: 99%

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Kraishtides (Kraištiden) 70 years later: Myth or Reality?

Zagorchev¹

2006

GeolBalc

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The notion of Kraishtides underwent considerable transformations during 70 years since its introduction in the tectonic nomenclature of the Balkan Peninsula. Initially it was introduced for the allegedly youngest (Early Miocene) fold and thrust (orogenic) zone (Krajštiden) situated obliquely to Balkanides and South Carpathians. This notion evolved into a fault belt composed of normal faults that were transformed into reverse faults (Krajštiden-Lineament), and in a lineament-geosynclinal zone (Kraishtid lineament-geosyncline) of repeated opening (in latest Jurassic, Palaeogene and Neogene times) of basins of rift character, and following (“Austrian”, “Pyrenean” and “Savian”) compression and closures. All these meanings of the term may be regarded as redundant now. They are inconsistent with the modern knowledge about the geological structure and evolution of the region, and do not fit the modern tectonic ideas. Only the term “Kraishtid (Strouma) Lineament” could be preserved as a synonym to “Strouma (Kraishtid) fault belt”. However, the word “Kraishtid (Krajštiden)” refers to an orogenic belt (zone), and cannot be preserved as a toponym of fault belt. “Kraishtides” are neither a structural zone with a definite characteristics. The structure of SW Bulgaria is a peculiar mosaic of fold zones and blocks. In the Late Jurassic – Early Cretaceous palaeogeodynamic setting, a part of this area was the westernmost part of the Nish-Troyan flysch trough whereas South of it, the largest area belonged to an uplifted “plateau”. In mid-Cretaceous times (Aptian – Albian), the “Austrian” orogenesis led to the closure of the relics of the flysch trough, and the formation of the complex Morava-Rhodope (Macedonian-Rhodope) zone (in its westernmost part composed of the Morava, Strouma, and Ograzhden units). In Late Cretaceous times, the whole Morava-Rhodope zone represented an area of thickened continental crust (elevated frontal arc, “plateau”) whereas North of it, the Srednogorie volcanic arc and see was opened. In Palaeogene times, the whole Morava-Rhodope zone was again a volcanic island arc with a WNW-ESE trend. Only in Palaeogene and Neogene times, the Strouma (Kraishtid) lineament played the role of a fault belt with considerable dextral strike-slip movements, and repeating rifting in transtensional conditions.

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