Balintoni, I., Puşte, A., Balica, C. and Stan, R. (2002): Păiuşeni Unit - version 1. In: Dunkl, I., Balintoni, I., Frisch, W., 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.uni-tuebingen.de/geo/met-map/index.html.
Păiuşeni Unit (PAA)
Compiled: I. Balintoni, A. Puşte, C. Balica and R. Stan (2002)
Age of Protolith, Geochemistry
Lithology, Mineralogy, Metamorphic Grade
Thermobarometry
Geochronology
Structural Evolution
Summary
Bibliography
Links
A rift type, Late Carboniferous (?) - Permian volcano-sedimentary sequence, pierced by Early Permian bimodal extensional intrusions, dynamo-thermal metamorphosed during Early Cretaceous period in the chlorite zone of the greenschist facies
Geographic Position
The Unit is exposed
in an approximate 100 km long and maximum 20 km large region, between the south-western termination of the Apuseni Mountains and the Avram Iancu village on the Arieşu Mic river.Maps
Geological Map of Romania 1:1.000.000 (Săndulescu et al., 1978)Boundaries
As a rule, the Paiuseni Unit transgressively covers the Biharia Unit or it is tectonically covered by this one. Northward it overthrusts the Codru Nappe System and sedimentary formations of the Garda Nappe, the lowermost unit of the Biharia Nappe System. The development of the Paiuseni Unit is conditioned by the extent of the Biharia Unit.
Structural Position
Within the Alpine structure of the Apuseni Mountains, the Păiuşeni Unit is situated in
the mid part of the Biharia Nappe System. The Biharia Nappe System underlain the Transylvanides and overlain the Codru Nappe System and the Bihor autochthon.Subunits
The Păiuşeni Unit has been divided in several lithotectonic assemblages, named according to each nappe name. Thus, down to up crop out the following subunits: Păiuşeni - Poiana; Păiuşeni - Piatra Grăitoare; Păiuşeni - Biharia; Highiş-Muncel. The individual subunits are characterized by differences in lithologies and the occurrence of meta-ign
eous rocks (Savu, 1961, Savu et al, 1967, Ionescu, 1962, Dimitrescu in Ianovici et al, 1976, Pana and Ricman, 1988, Balintoni and Puste, 2002).Correlation
The Apuseni Mountains crystalline is a part of the Preapulian block (Săndulescu, 1994), or Apulian microplate according to Mosar and Stampfli (1999). Balintoni, (1994) used the term Preapulian "craton". In virtue of this model possible correlation of the Păiuşeni Unit can be supposed in the West Carpathian metamorphosed Permian. But it can be a raw corre
lation, because the Biharia Nappe System has not a direct correspondent in the West Carpathians, and also the Gelenica Unit in West Carpathians is not correlable with the Biharia Unit in Apuseni Mountains, as proposed by Dimitrescu (in Ianovici et al, 1976).Age of Protolith, Geochemistry
For the sedimentation age exist some new paleontological data (Olaru and Dimitrescu, 1994) for the uppermost subunit of the Highiş Massif, indicating the Upper Carboniferous epoch. A confident Permian age has been obtained by Pană (1998), using the U/Pb zircon system from the bimodal intrusions, known in the Highiş Massif. The geochemical data (Tatu, 1988) suggest a bimodal alkaline magmatism of upper mantle affiliation for the above mentioned intrusio
ns. The magma were generated in a rift-related tectonic setting.Lithology, Mineralogy, Metamorphic Grade
The lithology is dominated by meta-sandstones, meta-conglomerates, and phyllites (lower subunits), interfingered with
meta-porphyres, meta-diorites and meta-granites (upper subunits). Locally appear carbonate lenses. In the Highiş Massif the great intrusions remained unmetamorphosed and unfoliated. In many places can be seen the transition from a magmatic unaltered nucleus to a foliated and altered margin with a phyllitic aspect. The metamorphic evolution involved the volcano-sedimentary suite as intrusions and their hornfels aureole. The metamorphic minerals are represented by albite, epidote, actinolite, chlorite, sphene and iron oxides in the metabasites, and by muscovite and chlorite in metapelites. The Alpine dynamo-thermal evolution defines a low-grade metamorphic event in the chlorite zone of the greenschist facies. The penetrative deformation was not uniform and many minerals remainined as sedimentary or magmatic relics.Pană (1998) used the calcite-dolomite solvus thermometer for evaluating the metamorphic temperatures. His data: 382°C and 313°C for samples from Agrişu Mare Valley and Highiş Valley respectively show incomplete resettings of the Permian contact metamorphism temperatures during the Cretaceous dynamo-thermal event. Savu et al. (1967) obtained homogenization temperatures for inclusions in quartz clasts rang
ing from 320°C to 285°C. Pană (1988) obtained on fluid inclusions from quartz grains in carbonate lenses 275°C to 135°C and 180°C to 90°C. All these data suggest a low-grade metamorphism during the Cretaceous event as the metamorphic minerals show.Table 1. Geochronological results obtained on, Păiuşeni Unit.
| Location |
Lithology |
Method |
Age (Ma) |
Source |
|
|
Highiş Valley, Căsoaia |
Sericite schist |
K/Ar (WR) |
113 |
Soroiu et al., 1969 |
|
|
Highiş Valley, Căsoaia |
Chl-Ms-Ab schist |
K/Ar (WR) |
115 |
Soroiu et al., 1969 |
|
|
Şiria fortress |
Metaconglomerate |
K/Ar (WR) |
123 |
Soroiu et al., 1969 |
|
|
Plateau age |
Total gas age |
||||
|
Corvin Quary |
Phylonite |
K/Ar (WR) |
114.1 |
114.1 |
Dallmeyer et al., 1999 |
|
Covăşuţ Hill |
Phylonite |
K/Ar (WR) |
99.7 |
106.1 |
Dallmeyer et al., 1999 |
|
Şiria fortress |
Metaconglomerate |
K/Ar (Ms) |
299.4 |
288.6 |
Dallmeyer et al., 1999 |
|
Crişcior Village |
Phylonitic granite |
K/Ar (WR) |
107.7 |
110.5 |
Dallmeyer et al., 1999 |
|
Băneşti Valley |
Metaconglomerate |
K/Ar (Ms) |
111.7 |
Dallmeyer et al., 1999 |
|
|
Arieşeni Village |
Green Phylonite |
K/Ar (WR) |
216.5 |
192.2 |
Dallmeyer et al., 1999 |
|
Drocea Mts. |
Metadolerite |
K/Ar (Fem.M.) |
115 ± 4 |
Pavelescu et al., 1975 |
|
|
Drocea Mts. |
Metadolerite |
K/Ar (Fem.M.) |
111 ± 4 |
Pavelescu et al., 1975 |
|
|
Drocea Mts. |
Metadolerite |
K/Ar (Fem.M.) |
75 ± 3 |
Pavelescu et al., 1975 |
|
|
Drocea Mts. |
Metadolerite |
K/Ar (Fem.M.) |
108 ± 4 |
Pavelescu et al., 1975 |
|
|
Cladova |
Alkali-diorite |
U/Pb zircons |
266.7 ± 3.8 |
Pană et al., 1998 |
|
|
Jernova |
Porphyry microgranite |
U/Pb zircons |
264.2 ± 2.3 |
Pană et al., 1998 |
|
|
Şiria fortress |
Metaconglomerate |
Sm/Nd (WR) |
1.68 Ga (t = 267) |
Pană et al., 1998 |
|
|
Căsoaia Valley |
Granite |
Sm/Nd (WR) |
1.96 Ga |
Pană et al., 1998 |
|
|
Cladova Valley |
Diorite |
Sm/Nd (WR) (267 Ma) |
1.35 Ga |
Pană et al., 1998 |
|
|
Jernova Valley |
Granite |
Sm/Nd (WR) (265 Ma) |
2.12 Ga |
Pană et al., 1998 |
WR: whole rock, Ms: Muscovite, Fem.M.: Femic minerals
The unit is split in several subunits, located in the mid
dle part of the Biharia Nappe System (Bleahu and Dimitrescu, 1963; Dimitrescu in Ianovici et al., 1976; Bleahu et al., 1981; Săndulescu, 1984; Dimitrescu, 1988; Balintoni, 1994, 1997, 1998, 2001; Balintoni and Puşte, 2002). The Biharia Nappe System is constituted from down to up by following pre-Gosau tectonic units: Gârda Nappe; Raviceşti Scale; Poiana Nappe; Piatra Grăitoare Scale; Biharia Nappe; Highiş-Muncel Nape; Baia de Arieş Nappe. Fragments of the Păiuşeni Unit have been described from the Poiana nappe, Piatra Grăitoare Scale, Biharia Nappe, Highiş-Muncel Nape. The Biharia Nappe System proceeded from the penninc margin of the Preapulian craton (Balintoni, 1994, 2001) during the Early Cretaceous. The Biharia Nappe System emplaced antithetically and the necessary heat to the metamorphic reactions has been supplied by the hot body of the Baia de Arieş Unit (for temperatures of Baia de Arieş Unit during the Early Cretaceous time, see Dallmeyer et al., 1999). Deformational studies on the Păiuşeni Unit rocks were realized by Dimitrescu et al. (1965), Pană and Ricman, (1988), Mihaela Dimitrescu (1997, 2000), Pană (1998). The conglomerate pebbles are NW-SE elongated, but controversies arisen regarding the overthrust displacement sense: from SE to NW, or from SW to NE? In our opinion, pebble elongations are parallel to the main tectonic transport direction.The Păiuşeni Unit Unit represents an Late Carboniferous (?) - Permian lithotectonic assemblage. It formed in a rift-related tectonic setting. The rifting affected the Biharia Unit, the present basement of the Păiuşeni Unit. The Late Paleozoic rifting can be connected to the post-Variscan instability of the new built Pangea. This event represents the beginning of the Alpine extensional pe
riod, during which individualized the Preapulian craton, too. The Apusenides proceeded from the Preapulian craton margins. The Biharia Nappe System has been sheared from its penninic margin during the Early Cretaceous times, when the Păiuşeni Unit rocks have been dynamo-thermally metamorphosed. The metamorphic heat and the deformational energy was supplied by the hot body of the overlying Baia de Arieş Unit.Balintoni, I. (1998): The Apuseni Mountains. CERGOP Monography of Southern Carpathians, 7 (37), 93-109, Warsaw Univ. Tech.
Balintoni, I. (1994): Structure of the Apuseni Mountains. ALCAPA II Field Guide-Book, Rom. Journ. Tect. Reg. Geol., 75, Suppl. 2, 51-58, Bucuresti.
Balintoni, I. (1997): Geotectonica terenurilor metamorfice din Romania. Ed. Carpatica, Cluj Napoca, 176pp.
Balintoni, I. (2001): Short outlook on the structure of the Apuseni Mountains. In: I. Bucur, S. Filipescu, E. Sasaran (Eds): Field Trip Guide, 4th Regional Meeting of IFAA, 9-17, Cluj Univ. Press.
Balintoni, I. and Puste, A. (2002): New lithostratigraphic and structural aspects in the southern part of the Bihor massif, Apuseni Mountains. Stud. Univ. Babes-Bolyai, Geologia, XLVII, 2, 13-18, Cluj Napoca.
Bleahu, M. and Dimitrescu, R. (1963): ): Geological Map of Romania sc. 1:100.000, Arieseni sheet, Inst. Geol. Bucuresti.
Bleahu, M., Lupu, M., Patrulius, D., Bordea, S., Stefan, A. and Panin, S. (1981): The structure of the Apuseni Mountains. In: Carpatho-Balkan Geological Association, XII Congress (Bucharest, Romania). Guide to excurtion B3, Inst. Geol. Geofiz. Bucuresti, 103pp.
Bleahu, M., Savu, M. and Borcos, M. (1967): Geological Map of Romania sc. 1:200.000, Brad sheet, Inst. Geol. Bucuresti.
Bleahu, M., Savu, M. and Borcos, M. (1967): Geological Map of Romania sc. 1:200.000, Brad sheet, Inst. Geol. Bucuresti.
Bordea, S., Dimitrescu, R., Mantea, Gh., Stefan, A., Bordea, J., Bleahu, M. and Costea, C. (1988): Geological Map of Romania sc. 1:50.000, Biharia sheet, Inst. Geol. Geofiz. Bucuresti.
Dallmeyer, R. D., Pana, D., Neubauer, F.and Erdmer, P. (1999): Tectonothermal evolution of the Apuseni Mountains, Romania: Resolution of Variscan versus Alpine events with 40Ar/39Ar ages. Journal of Geology, 107, 329-352.
Dimitrescu, R. (1988): Apuseni Mountains. In: V. Zoubek (ed.). Precambrian in younger fold belts. John Wiley&Sons, New York, 853-862.
Dimitrescu, R., Bleahu, M. and Lupu, M. (1977): Geological Map of Romania sc. 1:50.000, Avram Iancu sheet, Inst. Geol. Geofiz. Bucuresti.
Dimitrescu, R., Bleahu, M. and Lupu, M. (1977): Geological Map of Romania sc. 1:50.000, Avram Iancu sheet, Inst. Geol. Geofiz. Bucuresti.
Dimitrescu, R., Bordea, S. and Puricel, R. (1965): Nota asupra Paleozoicului din Regiunea Arieseni (Bihor). D. S. Inst. Geol., LI (1963-1964), 1, 351-364.
Dimitrescu, M. (1997): Considerations on the strain variation in the Arieseni Nappe of the South Bihor Nappe. Rev. Róum. Géologie, 41, 77-85, Bucuresti.
Dimitrescu, M. (2000): L’analyse du strain et ses implications pour l’etablissment des traces de la deformation dans les métaconglomérats des Monts Apuseni du Nord. Anu. Inst. Geol. Rom., part II, 9-27, Bucuresti.
Giusca, D., Savu, H. and Borcos, M. (1967): Asupra stratigrafiei sisturilor cristaline din Muntii Apuseni. St. Cerc. Geol. Geofiz. Geogr., 12, 1, 41-56, Ed. Acad. Rom., Bucuresti.
Ianovici, V., Borcos, M., Bleahu, M., Patrulius, D., Dimitrescu, R. and Savu, H. (1976): Geologia Muntilor Apuseni. Ed. Acad. Rom., Bucuresti, 661pp.
Ionescu, L. (1962): Cercetari geologice si petrografice in cristalinul Muntilor Bihor (Biharia). Anu. Com. Geol, XXXII, 167-198.
Mosar, I. and Stampfly, G. M. (1999): Pancardi: at the crossroad of Atlantic and Tethys ocean systems. Rom. J. Tect. Reg. Geol., 75, 2, 136-140, Bucuresti.
Olaru, L. and Dimitrescu, R. (1994): Contributions preliminaries à la connaisance de l’áge de la Série de Paiuseni du Massif Cristallin de Highis. Rom. J. Stratigraphy, 76, 1-5, Bucuresti.
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, 356p.
Pana, D. and Ricman, C. (1988): The lower complex of the Paiuseni series: a blastomylonitic belt. Rev. Roum. Géol. Géophys. Géogr., Ser. Géol., 32, 21-35.
Papiu et al (1965): Geological Map of Romania sc. 1:200.000, Arad sheet, Inst. Geol. Bucuresti.
Pavelescu, L., Pop, G., Ailenei, G., Ene, I., Soroiu, M. and Popescu, G. (1975): K-Ar age determinations from the Apuseni and Banat Mountains. Rev. Rom. Geophys, 19, 67-79.
Sandulescu, M. (1984): Geotectonica Romaniei. Et. Tehn., Bucuresti, 336pp.
Sandulescu, M. (1994): Overview on Romanian Geology. ALCAPA II Field Guide-Book, Rom. Journ. Tect. Reg. Geol., 75, Suppl. 2, 3-15, Bucuresti.
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.
Savu, H. (1961): Cercetari petrografice in cristalinul Masivului Drocea. D. S. Inst. Geol., XLIV (1956-1957), 11-34.
Savu, H., Borcos, M., Hanomolo, I., Hanomolo, A., Trifulescu, M. and Ioanidu, C. (1967): Date noi asupra stratigrafiei si petrologiei sisturilor cristaline din partea centrala a Muntilor Drocei. D. S. Inst. Geol., LIII (1965-1966), 1, 187-214.
Tatu, M. (1998): le Massif Highis (Roumanie), un exemple de l’evolution du magmatism alcalin anorogenique. PhD Thesis, Université de Paris-Sud, Centre d’Orsay, 206pp.
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