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)

Version 1

compiled: I. Dunkl and F. Koller (2001)


Age of Protolith, Geochemistry
Lithology, Mineralogy, Metamorphic Grade
Structural Evolution


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).

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).

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).

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).

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).

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).

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).



Range (n)


K/Ar amphibole



W. Frank (in Koller, 1985)

K/Ar white mica

ca. 21

19, 23 (2)

W. Frank pers. comm. (1992)

FT zircon


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).

Structural Evolution

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.


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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.

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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.

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Schönlaub, H. P. (1973): Schwamm-Spiculae aus dem Rechnitzer Schifergebirge und ihr stratigraphiser Wert. Jahrbuch der Geologischen Bundesanstalt, Wien, 116, 35-48.

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Tari, G., Horváth, F. and Rumpler, J. (1992): Styles of extension in the Pannonian Basin. Tectonophysics, 208, 203-219.

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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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