The problems of the post-Cenomanian tectonic evolution of the central parts of the Sredna Gora Zone. The wrench tectonics – how real is real?

Kounov, Alexandre; Gerdjikov, Ianko

doi:10.52321/geolbalc.49.2.39

Cited by 7 publications

(3 citation statements)

References 42 publications

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“…The Late Jurassic-Early Cretaceous ductile right-lateral shearing observed in the southern part of the Sakar Unit (Gerdjikov, 2005), as well as in the North Rhodope Unit (Naydenov et al, 2013), could be related to the formation of a major wrench zone separating the opposite-vergent thrust belts of the Rhodope to the south and the Strandzha, Sredna Gora and Balkan zones to the north (Fig. 6b, c; Naydenov et al, 2013) as it was suggested also for the Late Cretaceous-Paleogene evolution of the Maritsa fault zone (Kounov and Gerdjikov, 2020).…”

Section: Wrench and Retro-wedge Lower Unitsmentioning

confidence: 67%

On the Rhodopean protoliths and their Middle Jurassic to Early Cretaceous evolution. A review

Kounov,

Gerdjikov

2024

GeolBalc

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The Rhodope Massif represents a large high-grade metamorphic complex situated in the Balkan Peninsula, straddling the border between Bulgaria and Greece. Geological studies carried out during the last thirty years clearly established that the complex is composed of three major lithotectonic units characterized by differing protolith ages and Alpine thermotectonic evolution. The Rhodope Massif consists of Upper and Lower terranes representing continental fragments composed mainly of pre-Mesozoic magmatic rocks and covered by Early Mesozoic sedimentary sequences. These two entities are separated by an Intermediate Terrane comprising a Jurassic magmatic arc and its host rocks tectonically intercalated with Jurassic ophiolitic fragments together with the Early Mesozoic sediments. Detailed analyses of the previously published geochronological data revealed that the three main tectonic terranes were juxtaposed in the Late Jurassic–Early Cretaceous during the continental collision and northward subduction of the Lower and Intermediate terranes. These rocks experienced Middle Jurassic to Early Cretaceous high-pressure metamorphism, followed by high-temperature one accompanied by anatexis. At that time, the Upper Terrane was metamorphosed and deformed only partially. Being part of the European margin, this terrane represented an upper continental plate during the subduction, and therefore is not considered as a part of the Alpine Rhodope metamorphic complex. It is important to note that, although most of the present-day fabric and major tectonic zones in the Rhodope metamorphic complex are younger than Early Cretaceous, and therefore they postdate the geological evolution discussed in this study, they often reactivate the old boundaries between the main terranes and units.

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Section: Wrench and Retro-wedge Lower Unitsmentioning

confidence: 67%

On the Rhodopean protoliths and their Middle Jurassic to Early Cretaceous evolution. A review

Kounov,

Gerdjikov

2024

GeolBalc

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“…The north-vergent translations along the zone led to the deformation of the Upper Cretaceous sequences of the Chelopech Basin (Fig. 2; e.g., Kounov and Gerdjikov, 2020).…”

Section: Alpine Tectonic Zonesmentioning

confidence: 99%

Lower Paleozoic low-grade metamorphic units from the Central Balkan Zone, Bulgaria: tectonic relationships, framework and geodynamic significance

Gerdjikov¹,

Kounov²,

Lazarova³

et al. 2023

GeolBalc

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The Central Balkan Zone belongs to the north-vergent fold-and-thrust belt of the Alpine Balkan orogen. In this zone, pre-Permian low-grade rocks, metamorphosed during the Variscan orogeny, were later reworked at two main stages of the Alpine compressional tectonics. Several tectono-stratigraphic subdivisions of these metamorphic rocks were previously presented, based on a purely stratigraphic approach in the absence of detailed structural studies and, most importantly, of reliable paleontological and geochronological records. In this study, we propose a new framework of the low-grade metamorphic rocks from the Central Balkan Zone, applying a critical analysis of the existing data combined with new geochronological data and detailed lithological and structural observations. Based on the structural relationships and geochronological constraints, several new entities, such as the Korduna, Bilo and Zvezdets units, were established together with a reassessment of the previously recognized Diabase-Phyllitoid Complex (DPC). Both DPC and the Bilo Unit are now defined as Cambrian–Lower Ordovician (?) mélange complexes part of an accretionary wedge and/or forearc basin formed along the north Gondwanan margin. In the Bilo, Murgash and Etropole mountains, a tectonically uninterrupted Cambrian–Upper Ordovician section, characterized by a normal metamorphic gradient from low-grade to nonmetamorphosed terrigenous rocks, is recognized. The deposition of these sediments is related to the subduction of the Prototethys and the early evolution of the Rheic Ocean. An inverted metamorphic gradient recognized along the southern slopes of the Etropole and Zlatitsa-Teteven mountains through the Korduna and Zvezdets units is related to Variscan syn-metamorphic deformation in the Stargel-Bulovanya Tectonic Zone.

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“…Any original volcanic equivalents have been removed by erosion. A second Alpine compressional event affected the area after the Maastrichtian and caused substantial thrust faulting and folding of the Upper Cretaceous sequences [30,[42][43][44].…”

Section: Geological Settingmentioning

confidence: 99%

Sulfide Trace Element Signatures and S- and Pb-Isotope Geochemistry of Porphyry Copper and Epithermal Gold-Base Metal Mineralization in the Elatsite–Chelopech Ore Field (Bulgaria)

et al. 2023

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The Eletsite–Chelopech ore field in the northern part of the Panagyurishte district in Central Bulgaria comprises numerous spatially associated porphyry copper and epithermal gold deposits and prospects. In addition to the mineralization and alteration features, trace elements, lead and sulfur isotope signatures of sulfide minerals from porphyry copper, base metal and gold-base metal deposits/prospects have been studied. LA-ICP-MS analyses of pyrite, arsenopyrite and sulfosalt minerals validate them as major carriers for Au, Ag, Sb, Se and Co. Pyrite from the three types of mineralization has specific geochemical characteristics. Pyrite from the porphyry copper deposits/prospects has generally lower total trace element content compared to pyrite from the epithermal prospects, except for Se, Co and Ni. Pyrite from the base metal and gold-base metal veins is enriched in As, Au, Ag, Sb and Pb. In pyrite from the base metal deposits, Co and Ni have contents comparable to the pyrite from the porphyry copper deposits, while pyrite from the gold-base metal veins shows lower Co and Ni. Arsenopyrite from these deposits shows similar features. Similarly, sphalerite from the gold-base metal veins also has lower Co content compared to sphalerite from the base metal veins but higher In and Cu contents. In addition to the close spatial relationships between the Elatsite and Gorna Kamenitsa porphyry Cu deposits and Negarstitsa-West and Dolna Kamenitsa base metal prospects, as well as similarities in the mineralization and alteration styles, the lead isotopic (206Pb/204Pb = 18.61–18.68, 207Pb/204Pb = 15.64–15.65 for porphyry and 206Pb/204Pb = 18.55–18.67, 207Pb/204Pb = 15.64–15.68 for base metal) and sulfur isotopic (δ34S values of −3 to +1‰ for porphyry and δ34S values of −1.7 to +3.5‰ for base metal) signatures of sulfides support the idea of a genetic link between these two types of deposits. The porphyry and base-metal mineralization result from a common major ore-forming event during the Late Cretaceous, corresponding to deep/higher-temperature and shallower/distal/lower-temperature environments, respectively. In particular, more radiogenic lead (206Pb/204Pb = 18.41–18.47, 207Pb/204Pb = 15.67–15.76) and slightly different sulfur isotopic compositions (δ34S values of +3.5 to +10.6‰) of sulfides from the distal gold-base metal veins of Kordunsko Dere, Svishti Plaz and Shipkite might be a consequence of the interaction of the ore-forming fluids with an external older crustal and isotopically positive S source. Alternatively, a different fluid source/event for the formation of these gold-base metal veins may be suggested.

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The problems of the post-Cenomanian tectonic evolution of the central parts of the Sredna Gora Zone. The wrench tectonics – how real is real?

Cited by 7 publications

References 42 publications

On the Rhodopean protoliths and their Middle Jurassic to Early Cretaceous evolution. A review

On the Rhodopean protoliths and their Middle Jurassic to Early Cretaceous evolution. A review

Lower Paleozoic low-grade metamorphic units from the Central Balkan Zone, Bulgaria: tectonic relationships, framework and geodynamic significance

Sulfide Trace Element Signatures and S- and Pb-Isotope Geochemistry of Porphyry Copper and Epithermal Gold-Base Metal Mineralization in the Elatsite–Chelopech Ore Field (Bulgaria)

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