Balintoni, I., Puşte, A., Stan, R. and Balica, C. (2002): Vulturese - Belioara Unit - version 1. In: Dunkl, I., Balintoni, I., Frisch, W., Hoxha, L., Janák, M., Koroknai, B., Milovanovic, D., Pamić, J., Székely, B. and Vrabec, M. (Eds.): Metamorphic Map and Database of Carpatho-Balkan-Dinaride Area. http://www.met-map.uni-goettingen.de
Vulturese - Belioara Unit (VBA)
Compiled: I. Balintoni, A. Puşte, R. Stan and C. Balica
Age of Protolith, Geochemistry
Lithology, Mineralogy, Metamorphic Grade
Structural Evolution
Summary
Bibliography
Links
Definition
A quartzite and carbonate sequence of Triassic age. Dynamo-thermally metamorphosed in the chlorite zone during the Early Cretaceous period.
Geographic Position
Vulturese - Belioara Unit is exposed in the eastern part of the Biharia Nappe, the main component of the Biharia Nappe System, between Ocolisel and Salciua brooks. It crops out in three prolonged bodies displaced by transversal faults, around 20 km long in all. Its width does not exceed 2 km.
Maps
Geological Map of Romania 1:1.000.000 (Săndulescu et al., 1978)
Geological Map of Romania 1:200.000, Turda sheet (Lupu et al., 1967)
Geological Map of Romania 1:50:000, the sheets Poşaga (Balintoni et al., 1987) and Valea Ierii (Hârtopanu et al., 1982),
Additional map: Mârza, (1965, 1969), Dimitrescu in Ianovici et al., (1976).
Boreholes
A drilling placed in the Runc Valley, crossed the carbonate pile, quartzitic metaconglomerates and entered the Biharia Unit rocks.
Boundaries
The Vulturese - Belioara Unit appears as a fragmented strip along the contact between Baia de Arieş Unit and Biharia Unit. Toward east it is covered by Upper Cretaceous sediments.
Structural Position
The footwall is represented by its normal basement, the Biharia Unit. The hanging wall is formed by the tectonically superimposed Baia de Arieş Unit. In the eastern Apuseni Mountains the Biharia Nappe is the second unit of the Biharia Nappe System (from down to up).
Subunits
The Vulturese - Belioara Unit was not divided in subunits.
Correlation
Evidently, lithostratigraphically it is correlable with the peri-Tethyian platform Triassic. This correlation has been recognized by Dimitrescu (in Ianovici et al., 1976) and Trümpy (personal information, 1994) with the metamorphosed Triassic of the Western Carpathians and the Austroalpine one, respectively.
Age of Protolith, Geochemistry
The age is supposed, no paleontologically proved. Because this sequence transgressive overlies the Biharia Unit rocks and it can not be stratigraphically correlated with the Păiuşeni Unit, the Triassic age is highly probable. The Lower Triassic has a comparable, mainly carbonatic lithostratigraphy in many places along the peri-Tethysian platforms. Pană (1998) performed some 13C and 18O analyses on carbonate rocks of the Vulturese - Belioara Unit. The data range between 26 to 29 for 18O, suggesting weakly metamorphosed marine limestones.
Lithology, Mineralogy, Metamorphic Grade
The sequence begins with quartz metaconglomerates and sericite-quartzites followed by black, graphite-dolomites and white marbles Mârza (1965, 1969). This succession can be recognized on several cross-sections. Sometimes, the succession repeats vice-versa on the same cross-section, what suggests a tight folding. As recrystallised minerals have been cited sericite, graphite, calcite, dolomite, ankerite and goethite.
The Vulturese - Belioara Unit undergone a low grade metamorphism, in the same P-T conditions as the Păiuşeni Unit in Early Cretaceous time. The heat source was the hot body of the Baia de Arieş Unit and the deformational energy. The Baia de Arieş Unit rocks overlying the Vulturese - Belioara Unit are strongly retrogressed and mylonitized.
Structural Evolution
The unit appears as being strongly folded in a quite ductile manner (Mârza, 1965) during the Baia de Arieş Nappe emplacement. The folding scale is kilometric and one can not say clearly if there is an anticline or a syncline, because the limbs are often parallel and the hinge is not visible in outcrop scale.
The Vulturese - Belioara Unit represents a patch of Triassic platform rocks deposited on the Biharia Unit metamorphics. It was metamorphosed during Early Cretaceous times similar to Păiuşeni Unit rocks, due to emplacement of the Baia de Arieş Unit hot body over it.
Balintoni, I. (1997): Geotectonica terenurilor metamorfice din Romania. Ed. Carpatica, Cluj Napoca, 176pp.
Balintoni, I., Lupu, M., Iancu, V. and Lazar C. (1987): Geological Map of Romania sc. 1:50.000, Posaga sheet, Inst. Geol. Geofiz. Bucuresti.
Hartopanu, I., Hartopanu, P., Balintoni, I., Borcos, M., Rusu, A. and Lupu, M. (1982): Geological Map of Romania sc. 1:50.000, Valea Ierii sheet, Inst. Geol. Geofiz. Bucuresti.
Ianovici, V., Borcos, M., Bleahu, M., Patrulius, D., Dimitrescu, R. and Savu, H. (1976): Geologia Muntilor Apuseni. Ed. Acad. Rom., Bucuresti, 661pp.
Lupu, M., Borcos, M., Dimian, M., Lupu, D. and Dimitrescu, R. (1967): Geological Map of Romania sc. 1:200.000, Turda sheet, Inst. Geol. Bucuresti.
Marza, I. (1965): Unitatea petrografica si paleostratigrafica a masivelor de carbonati metamorfici: Vulturese-Scarisoara-Llurda (Bazinul Ariesului). Anal. Univ. Bucuresti, Seria St. Nat., Geol.-Geogr., XIV, 9-16.
Marza, I. (1969): Evolutia unitatilor cristaline din sud-estul Muntelui Mare. Ed. Acad. Rom., Bucuresti, 166p.
Pana, D. (1998): Petrogenesis and tectonics of the basement rocks of the Apuseni Mountains: significance for the Alpine tectonics of the Carpatho-Pannonian region. PhD Thesis, University of Alberta, Canada, 356pp.
Sandulescu, M., Kräutner, M., Borcos, M., Nastaseanu, S., Patrulius, D., Stefanescu, M., Ghenea, C., Lupu, M., Savu, H., Bercia, I. and Marinescu, F. (1978): Geological Map of Romania, sc. 1:1.000.000, Inst. Geol. Geofiz. Bucuresti.
Descriptions of the neighbouring Units:
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