Dunkl, I. and Koller, F. (2001): Penninic of the Rechnitz window group - 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.met-map.uni-goettingen.de
Penninic of the Rechnitz window group (REW)
compiled: I. Dunkl and F. Koller (2001)
completed:
Age of Protolith, Geochemistry
Lithology, Mineralogy, Metamorphic Grade
Thermobarometry
Geochronology
Structural Evolution
Summary
Bibliography
Links
Metasedimentary and metaophiolitic sequences of Mesozoic protolith age, experienced Tertiary greenschist facies metamorphism (Pahr, 1980; Ratschbacher et al., 1989, 1991b; Tari et al., 1992).
Geographic Position
Exposed in three small windows at the eastern margin of the Eastern Alps. Maximum extent is approx 50 km x 50 km, but the majority of the Unit is covered by Neogene sediments (Flügel, 1988).
Maps
Surface exposures: 1:50000 Pahr, (1984); Koller, (1985); Ferencz et al., (1988), 1:200,000 Schönlaub et al. (2000). Subsurface extent: 1:200,000 Flügel (1988).
Boreholes
Some boreholes penetrating the Unit:
Szombathely Sz-II (greenschist): Lelkes-Felvári (1994);
Maltern 1 (serpentinite, greenschist): Schönlaub (2000);
S7, R4, R5, SB 03, CF W2, CF K1, Güssing 1 (Penninic formations), Flügel (1988).
Boundaries
The bordering structural elements are predominantly low angle normal faults (Pahr, 1980; Ratschbacher et al., 1989, 1991b; Tari et al., 1992; Dunkl et al., 1998).
Structural Position
The footwall is unknown (it is supposed to be the European crystalline basement), the hanging wall formations are Middle and Upper Austrolapine metamorphites (Austroalpine(?) - Tatric Unit and the Paleozoic of Graz).
Subunits
According to the structural position of metamorphic lithologies (from up to down):
- greenschist,metagabbros, serpentinites,
- meta-conglomerate (only locally),
- calcareous and graphitic phyllite, Locally rather pure marbles), and
- quartzphyllite sequences were distinguished by Pahr (1977) and Császár and Haas (1983).
Correlation
These are the easternmost exposures of the Penninic mega-unit of the Alps. Similar "Bündenschiefer" and greenschist sequences are exposed in the Tauern Window (Glockner nappe) and farther on in the Central Alps - where the metamorphic grade can reach the amphibolite facies (Koller, 1985).
Age of Protolith, Geochemistry
The only exact age determination exist for the age of the sedimentation: Schönlaub (1973) found middle Cretaceous sponge spicula in calcschists. The supposed range of sedimentation is from Early Jurassic to Late Cretaceous (maybe until earliest Paleogene).
The geochemical signatures indicate high Ti ophiolitic character (Koller, 1985) derived from a depleted mantle source and formed at a well developed middle oceanic rigde system with rather low spreading rates. Local occurrence of chromite-bearing ophicarbonates argue an early exposure of the mantle sequence within the oceanic environment (Höck and Koller, 1989). Geochemistry as well as isotope data define a clear relation to the ophiolites of the Penninic window in the west (Meisel et al., 1997; Melcher et al., in press).
Lithology, Mineralogy, Metamorphic Grade
Phyllites, calcareous phyllite, quartzites, conglomerate and a greenschist dominated ophiolite complex with ultramafitite, gabbro and plagiogranite members including also local ophicarbonate sequences.
The metamorphic evolution can be divided into an oceanic metamorphism event and the alpicdic event with a blueschist facies overprint followed by a greenschist facies thermal reequilibration (Hoinkes et al., 1999) The oceanic event is restricted to the ophiolite sequence and is documented by barroisite, Ti-rich pargasite and Mg-hornblende in the metabasic rocks and Cr-andradite in the ophicarbonates and by a locally high oxidation rate (Koller, 1985).
The Alpidic metamorphic evolution define a low-T and high-P event in blueschist facies with common remnants in the ophiolite sequence and rare in the metasedimentary succession. The high pressure event is followed by the thermal peak in greenschist facies, which is common for all rock types with an increase from the north to the south of the windows (Koller, 1985; Hoinkes et al., 1999).
Thermobarometry
Three metamorphic events have been recorded in the Rechnitz series:
1) oceanic hydrothermal activity (T > 750 °C) formed barroisite, pargasite, and Mg-hornblende.
2) Subduction-related HP/LT metamorphism (T = 330-370 °C, p = 6-8 kbar) with mineral paragenesis consisting of Mg-rich pumpellyite, ferroglaucophane, alkalipyroxene (~Ac63Jd21), lawsonite (formrelics) and stilpnomelane.
3) Late Alpine greenschist facies metamorphism (T = 350-430 °C, p < 3 kbar) with actinolite, alkalipyroxene (~Ac85Jd<5), riebeckite or Mg-riebeckite (Lelkes-Felvári, 1982; Kubovics, 1983; Koller, 1985).
|
Mean |
Range (n) |
Source |
|
|
K/Ar amphibole |
65±6 |
(1) |
W. Frank (in Koller, 1985) |
|
K/Ar white mica |
ca. 21 |
19, 23 (2) |
W. Frank pers. comm. (1992) |
|
FT zircon |
17.3±2.2 |
13.5-21.9 (17) |
Dunkl and Demény (1997) |
|
FT apatite |
ca. 8.5 |
7.3, 9.7 (2) |
-"- |
Distribution of zircon fission track ages in the Rechnitz and Bernstein Windows. Contour values are in million years, sample locations are indicated by triangles (from Dunkl and Demény, 1997).
The Unit is strongly folded, consists of several internal nappes (Ratschbacher et al., 1990; Dudko and Younes, 1990; Wiedemann and Younes, 1990; Neubauer et al., 1992). The Penninic formations were exhumed during Middle Miocene crustal extension (Tari and Bally, 1990 and Dunkl and Demény, 1997). The details of thermal modeling is presented by Dunkl et al. (1998).
The exposed rock sequences of the Rechnitz window group define rather clearly a formation of a Jurassic oceanic crust with a subsequent oceanic sedimentation mainly rich in marly pelites. This sequence was subducted during the closure of the South Penninic ocean and incorporated into the Alpine nappe pile during the Tertiary evolution of the Alps.
Árkai, P. and Balogh, K. (1989): The age of metamorphism of the East Alpine type basement, Little Plain, W-Hungary: K-Ar dating of K-white micas from very low- and low-grade metamorphic rocks. Acta Geologica Hungarica, 32, 131-147.
Bandat, H. (1928): Geology of the western part of the Kôszeg-Rechnitz Mountains. Földtani Szemle, 1, 1-24.
Bandat, H. (1932): Die geologische Verhaltnisse des Kôszeg-Rechnitzer Schifergebirge. Földtani Szemle, 1, 140-186.
Bigi, G. et al. eds. (1990): Structural model of Italy 1:500.000, Sheet N.1.
Császár, G. and Haas, J. (eds.) (1983): Lithostratigraphic formations of Hungary. Hung. Geol. Institute, Budapest, 1 p.
Demény, A. (1988): Determination of ancient erosion by zircon morphology and investigations on zoned tourmaline in the Kôszeg Rechnitz Window (Western Hungary). Acta Mineralogica-Petrographica, 29, 13-26, Szeged.
Demény, A. and Dunkl, I. (1991): Preliminary zircon fission track results in the Kôszeg Penninic unit. Acta Mineralogica-Petrographica, 32, 43-47, Szeged.
Demény, A. and Kreulen, R. (1993): Carbon isotope ratios of graphites in the Bündnerschiefer series of the Tauern Window and the Kőszeg-Rechnitz Windows (Austria and western Hungary): origin of organic matter and sedimentary facies correlation. Geologica Carpathica, 44, 3-9.
Dudko, A. and Younes M. T. (1990): Alpine plastic deformation in the Köszeg Mountains (Hungary). Földtani Közlöny, 120, 69-82.
Dunkl, I. and Demény, A. (1997): Exhumation of the Rechnitz Window at the border of Eastern Alps and Pannonian basin during Neogene extension. Tectonophysics, 272, 197-211.
Dunkl, I. (1992): Final episodes of the cooling history of eastern termination of the Alps. in: Neubauer, F. (ed): Geological evolution of the internal Eastern Alps and Carpathians and of the Pannonian Basin (ALCAPA) - Field Guide, Graz, 137-139.
Dunkl, I., Neubauer, F., Dallmeyer, D., and Müller, W. (1993): Cooling history and structure of a complex extensional region: the eastern margin of the Alps. Terra Abstract, 5, 234.
Dunkl, I., Grasemann, B. and Frisch, W. (1998): Thermal effects of exhumation of a metamorphic core complex on hanging wall syn-rift sediments - an example from the Rechnitz Window, Eastern Alps. Tectonophysics, 297, 31-50.
Ferencz, K., Hermann, P. and Pahr, A. (1988): Geologische Karte der Republik Österreich 1:50000. Erläuterungen zu Blatt 138 Rechnitz. 40 p. Geologische Bundesanstalt, Wien.
Finger, F. and Neumayr, P. (1990): Identifizierung einer Paragneisauflagerung am Granitgneis des östlichen Tauernfensters (Ostalpen) als autochthones Sediment mit Hilfe vergleichender Zirkonuntersuchungen. Schweizerische Mineralogische und Petrographische Mitteilungen, 70, 397-402.
Flügel, H. W., 1988. Steirisches Becken- Südburgenländische Schwelle; Geologische Karte des prätertiären Untergrundes 1:200,000. Geologische Bundesanstalt, Wien.
Földváry, A., Noszky, J., Szebényi L. and Szentes, F. (1948): Geological observations in Köszeg Mountains. Jelentés a Jövedéki Mélykutatás 1947/1948. Évi Munkálatairól (Budapest), 5-31.
Frank, W., Kralik, M., Scharbert, S. and Thöni, M. (1987): Geochronological data from the Eastern Alps. in: Flügel, H. and Faupl, P. (eds): Geodynamics of the Eastern Alps, 270-281.
Höck, V. and Koller, F. (1989): Magmatic evolution of the Mesozoic ophiolites in Austria. Chemical Geology, 77, 209-227.
Hoinkes, G., Koller, F., Rantisch, G., Dachs, E., Höck, V., Neubauer, F. and Schuster, R. (1999): Alpine metamorphism of the Eastern Alps. Schweizerische Mineralogische und Petrographische Mitteilungen. 79, 155-181.
Horváth, F. (1993): Towards a mechanical model for the formation of the Pannonian basin. Tectonophysics, 226, 333-357.
Juhász, Á. (1965): Sedimentpetrographische Untersuchungen am Konglomerat von Cák. Földtani Közlöny, 95, 313-319.
Koller, F. (1985): Petrologie und Geochemie der Ophiolite des Penninikums am Alpenostrand. Jahrbuch der Geologischen Bundesanstalt, Wien, 128, 83-150.
Koller, F. and Pahr, A. (1980): The Penninic ophiolites on the eastern end of the Alps. Ofioliti, 5, 65-72.
Kubovics, I. (1983): Petrological characteristics and genetic features of the crossitite from Western Hungary. Földtani Közlöny, 113, 207-224.
Kubovics, I. (1985): Mesozoic magmatism of the Transdanubian Mid-Mountains. Acta Geologica Hungarica, 28, 141-164.
Lelkes-Felvári, Gy. (1994): Penninic and Upper Austroalpine Units (Paleozoic of Graz ?) in the borehole Szombathely-II (Western Hungary). in: Lobitzer, H., Császár, G. and Daurer, A. (eds): Jubiläumsschrift 20 jahre Geologische Zusammenarbeit Österreich-Ungarn. 379-382.
Lelkes-Felvári, Gy. (1982): A contribution to the knowledge of the Alpine metamorphism in the Kôszeg-Vashegy area (Western Hungary). Neues Jahrbuch Geol. Paläont. Mh., 5, 297-305.
Mauritsch, H. J., Márton, E. and Pahr, A. (1991): Paleomagnetic investigations in highly metamorphosed rocks: Eastern Alps (Austria and Hungary). Geophys. Trans., 36, 49-65.
Meisel, Th., Melcher, F., Tomascak, P., Dingeldey, Ch. and Koller, F. (1997): Re-Os isotopes in orogenic peridotite massifs in the Eastern Alps, Austria. Chemical Geology, 143, 217-229.
Melcher, F., Meisel, T., Puhl, J. and Koller, F. (in press): Petrogenesis and geotectonic setting of ultramafic rocks in the Eastern Alps: constraints from geochemistry. Lithos.
Mostler, H. and Pahr, A. (1981): Triasfossilien im "Cáker Konglomerat" von Goberling. Verh. der Geologischen Bundesanstalt, Wien, 83-91.
Neubauer, F., Dallmeyer, R. D., Dunkl, I., Ebner, F., Fritz, H., Handler, R., Hubmann, B., Koller, F., Müller, W., Peindl, P., Wallbrecher, E., Kiesl, W., Takasu, A. and Weinke, H. H. (1992): Excursion to the Eastern Central Alps: descriptions of stops. in: Neubauer, F. (ed.. Geological evolution of the internal Eastern Alps and Carpathians and of the Pannonian Basin (ALCAPA) - Field Guide, Graz, 201-245.
Oravecz, J. (1979): Geologische Untersuchung des Cáker Konglomerates. Földtani Közlöny, 109, 14-23.
Pahr, A. (1977): Ein neuer Beitrag zur Geologie des nordöstlichen Sporns der Zentralalpen. Verh. Geol. Bundesanst. Wien, pp. 23-33.
Pahr, A. (1980): Die Fenster von Rechnitz, Bernstein und Möltern. in Der geologische Aufbau Österreich (ed: Oberhauser, R.), Springer V., 320-326.
Pahr, A. (1984): Gelogische Karte der Republik Österreich, 1:50000, Erläuterungen zu Blatt 137 Oberwart. Geologische Bundesanstalt, Wien, 47 p.
Ratschbacher, L., Frisch, W., Neubauer, F., Schmid, S. M. and Neugebauer, J. (1989): Extension in compressional orogenic belts: The Eastern Alps. Geology, 17: 404-407.
Ratschbacher, L., Behrmann, J. H. and Pahr, A. (1990): Penninic windows at the eastern end of the Alps and their relation to the intra-Carpathian basins. Tectonophysics, 172, 91-105.
Ratschbacher, L., Merle, O., Davy, P. and Cobbold, P. (1991a): Lateral extrusion in the Eastern Alps, Part 1: boundary conditions and experinemts scaled for gravity. Tectonics, 10, 245-256.
Ratschbacher, L., Frisch, W. and Linzer, H.-G. (1991b): Lateral extrusion in the Eastern Alps, Part 2: structural analysis. Tectonics, 10, 257-271.
Schönlaub, H. P. (1973): Schwamm-Spiculae aus dem Rechnitzer Schifergebirge und ihr stratigraphiser Wert. Jahrbuch der Geologischen Bundesanstalt, Wien, 116, 35-48.
Schönlaub, H. P. (2000): Burgenlad - Erläuterungen zur Geologischen Karte des Burgenlandes 1:200 000. Geologische Bundesanstalt Wien, 130 p.
Tari, G. and Bally, A. W. (1990): Metamorphic core complexes at the boundary of the Eastern Alps and the Pannonian basin. Geological Society of America, Abstract with Programs, 97-98.
Tari, G., Horváth, F. and Rumpler, J. (1992): Styles of extension in the Pannonian Basin. Tectonophysics, 208, 203-219.
Tollmann, A. (1980): Geology and tectonics of the Eastern Alps (Middle Sector). Abh. der Geologischen Bundesanstalt, Wien, 34, 197-255.
Wiedemann, R. and Younes, M. T. (1990): Studien zur Gefügeentwicklung (Quarzkorngefügeanalyse) im Penninikum von Recnitz/Köszeg (Österreich/Ungarn). Jahrbuch der Geologischen Bundesanstalt, Wien, 133, 385-394.
Descriptions of the neighbouring Units:
Austroalpine Basement Unit (AAB)
Paleozoic of Graz (PZG)
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