U-Pb detrital zircon geochronology of the lower Danube and its tributaries; implications for the geology of the Carpathians

We performed a detrital zircon (DZ) U-Pb geochronologic survey of the lower parts of the Danube River approaching its Danube Delta- Black Sea sink, and a few large tributaries (Tisza, Jiu, Olt and Siret) originating in the nearby Carpathian Mountains. Samples are modern sediments. DZ age spectra reflect the geology and specifically the crustal age formation of the source area, which in this case is primarily the Romanian Carpathians and their foreland with contributions from the Balkan Mountains to the south of Danube and the East European Craton. The zircon cargo of these rivers suggests a source area that formed during the latest Proterozoic and mostly into the Cambrian and Ordovician as island arcs and backarc basins in a Peri-Gondwanan subduction setting (~600 -440 Ma). The Inner Carpathian units are dominated by a U-Pb DZ peak in the Ordovician (460-470 Ma) and little inheritance from the nearby continental masses, whereas the Outer Carpathian units and the foreland has two main peaks, one Ediacaran (570-610 Ma) and one in the earliest Permian (290-300 Ma), corresponding to granitic rocks known regionally. A prominent igneous Variscan peak (320-350 Ma) in the Danube’s and tributaries DZ zircon record is difficult to explain and points out to either an extra Carpathian source or major unknown gaps in our understanding of Carpathian geology. Younger peaks corresponding to arc magmatism during the Alpine period make up as much as about 10% of the DZ archive, consistent with the magnitude and surface exposure of Mesozoic and Cenozoic arcs

New lithostratigraphic and structural aspects in the southern part of the Bihor Massif (Apuseni Mountains)

The Muncel Series (Ionescu, 1962), from the Bihor massif can be included in the Permian Pă ius̡eni Lithogroup, because it consists predominantly from weak metamorphosed granites and porphyres. In this idea, the Highis̡ Nappe correlates with the Muncel Nappe and does not with the Poiana Nappe. Consequently, the down to up succession of the Biharia Nappe System becomes: the Gârda Nappe; The Ravices̡ti scale; the Poiana Nappe; the Piatra Grăitoare scale; the Biharia nappe; the Highis̡-Muncel Nappe; the Baia de Aries̡ Nappe

New lithostratigraphic and structural aspects in the southern part of the Bihor Massif (Apuseni Mountains)

The Muncel Series (Ionescu, 1962), from the Bihor massif can be included in the Permian Pă ius̡eni Lithogroup, because it consists predominantly from weak metamorphosed granites and porphyres. In this idea, the Highis̡ Nappe correlates with the Muncel Nappe and does not with the Poiana Nappe. Consequently, the down to up succession of the Biharia Nappe System becomes: the Gârda Nappe; The Ravices̡ti scale; the Poiana Nappe; the Piatra Grăitoare scale; the Biharia nappe; the Highis̡-Muncel Nappe; the Baia de Aries̡ Nappe

Structural Researches in the Eastern Carpathians (in Romanian)

Structural Researches in the Eastern Carpathians. The Alpine mesoscopic lineations in the East Carpathians metamorphics, are NW-SE orientated. A few lineations, nearly E-W orientated, could be proved as pre-Alpine in age. Within the Ditrău Massif, is conserved a pre-Alpine attitude of foliations, as frozen magmatic flow, along the metamorphic pre-Triassic fabric. The lineation directions were conditioned by the Cretaceous-Tertiary contractional elimination of the External Carpathian Flysch Basin

Structural Researches in the Eastern Carpathians (in Romanian)

Structural Researches in the Eastern Carpathians. The Alpine mesoscopic lineations in the East Carpathians metamorphics, are NW-SE orientated. A few lineations, nearly E-W orientated, could be proved as pre-Alpine in age. Within the Ditrău Massif, is conserved a pre-Alpine attitude of foliations, as frozen magmatic flow, along the metamorphic pre-Triassic fabric. The lineation directions were conditioned by the Cretaceous-Tertiary contractional elimination of the External Carpathian Flysch Basin

The Arieseni Nappe, or the Moma and Poiana Nappes?

The Arieseni Nappe was the single tectonic unit of the Biharia Nappe System involving unmetamorphosed, red Permian and metamorphosed, green Permian deposits. Deformational, microscopic and x-Ray diffraction studies, suggest a tectonic relationship between the two sequences. Consequently, the red Permian deposits have been attributed to the Moma Nappe, and the green Permian rocks to the Poiana Nappe. Thus, the Arieseni Nappe disappeared. The thrust between the red Permian and the green Permian deposits realized later during the emplacement of Apusenides, due to an east-verging movement

The Arieseni Nappe, or the Moma and Poiana Nappes?

The Arieseni Nappe was the single tectonic unit of the Biharia Nappe System involving unmetamorphosed, red Permian and metamorphosed, green Permian deposits. Deformational, microscopic and x-Ray diffraction studies, suggest a tectonic relationship between the two sequences. Consequently, the red Permian deposits have been attributed to the Moma Nappe, and the green Permian rocks to the Poiana Nappe. Thus, the Arieseni Nappe disappeared. The thrust between the red Permian and the green Permian deposits realized later during the emplacement of Apusenides, due to an east-verging movement