Palaeomagnetism and palaeogeography of the Western Carpathiansfrom the Permian to the Neogene

MIROSLAV KRS, MARTA KRSOVA & PETR PRUNERGeological Institute, Academy of Sciences of the Czech Republic, Rozvojova 135, 165 00

Prague 6, Czech Republic

Abstract: Geodynamic models for the Western Carpathians require evaluation ofpalaeomagnetic data from the Outer Carpathian flysch belt, from limestones of the KlippenBelt and from volcanic and sedimentary rocks of the Inner Carpathians. Palaeomagneticdata for the Permian to the Neogene are evaluated. The data indicate marked, mostlyanticlockwise tectonic rotations of larger rock complexes and nappes. The distribution ofpalaeomagnetic poles is characteristic of a collision zone, and crosses the apparent polarwandering path for the African plate. Tectonic rotations are observed in both the InnerCarpathians and the Klippen Belt as well as in the Outer Carpathian flysch belt. Most driftoccurred during the Permian to Triassic interval, with northward movement from initialsouthern equatorial latitudes. Drift decelerated from the Jurassic to the Neogene.

Fig. 1. Simplified geological map of the Western Carpathians, showing the localities mentioned in the text.

The Carpathian Mountains represent a complexAlpine fold and thrust belt which is over 1500 kmlong and has a pronounced arcuate shape.Figure 1 shows that part of the WesternCarpathians within the territories of Slovakiaand Moravia. The system can be subdivided intothree main tectonostratigraphic zones, namelythe Outer Zone or Outer Carpathian flysch belt,

the Klippen Belt and the Inner Zone or InnerCarpathians. This paper summarizes palaeo-magnetic data obtained in the Western Car-pathians from units of Permian to Neogene ageby various authors. These data come from flyschdeposits of the Outer Carpathians, limestones ofthe Klippen Belt, and volcanic and sedimentaryrocks of the Inner Carpathians, and mainly come

From Morris, A. & Tarling, D. H. (eds), 1996, Palaeomagnetism and Tectonics of theMediterranean Region, Geological Society Special Publication No. 105, pp. 175-184.

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176 M. KRS ET AL.

Fig. 2. Stereographic projection of pole positions for the Alpine-Carpathian-Pannonian zone from thePermian to the Neogene.

from Slovakia, east Moravia and northHungary.

The first palaeomagnetic paper on this regionsuggested the presence of tectonic rotations ofvarying magnitudes and in different senses(Kotasek & Krs 1965). Subsequent synthesesexplained the observed declinations in terms ofrotational deformation of nappes or blocksduring Alpine folding (Krs et al. 1982). Astatistical evaluation of Phanerozoic palaeomag-netic data for the Eurasian and African con-tinents outlined striking rotations about verticalaxes for the whole Alpine belt. It was noted thatCretaceous rocks to the west of the WesternCarpathians had experienced rotations in apredominant clockwise sense (Krs 1982). Sub-sequent syntheses of palaeomagnetic data fromthe region (Marton 1987; Marton et al. 1987;Marton & Mauritsch 1990) resulted in documen-tation of tectonic rotations in different parts ofthe Alpine-Carpathian-Pannonian zone.

The present paper summarises data presentedin several publications (Mauritsch & Becke1987; Irving et al. 1976; Marton et al. 1988;Patrascu et al. 1990), and in others which are noteasily obtainable outside the Czech Republic(e.g. Krs et al. 1982; Krs 1982; and internalreports of the Geological Institute of the

Academy of Sciences and the Geofyzika BrnoCompany). In this review, only mean polepositions with values of a95 < 15° and к > 5 areconsidered to be statistically well defined. Onthis basis, reliable poles have been defined fornappes in the Northern Apennines, the West-ern, Southern, Eastern and Northeastern Alps,Istria, the Transdanubian Mountains, theOuter, Western and Eastern Carpathians, andthe Inner Carpathians (including the LittleCarpathian Mountains). These data verify theGondwanan affinity of the Carpathian areaduring the Mesozoic. Palaeogeographic affinityto the African plate can also be proven for theNorthern Apennines, Southern Alps, Istria andthe Transdanubian Mountains, on the basis ofsense of rotation (prevailingly anticlockwise)and on absolute values of paleolatitudes. Someother areas exhibit similar affinity, such as theEastern Alps and the Inner Carpathians,although the statistical reliability is lower. TheNorthern Apennines, Southern Alps and

show similar declinations from the Permian untilthe Cretaceous. An anomalous clockwise ro-tation occurs in the Northeastern Alps (shownby data from Jurassic and Cretaceous units) andthe Outer Eastern Carpathians (shown by datafrom Jurassic units, and tentatively by data from

PERMIAN-NEOGENE, WESTERN CARPATHIANS 177

Cretaceous rocks). Tectonic rotations give rise toscatter of palaeomagnetic pole positions. Figure2 shows the pole positions for the Alpine-Carpathian-Pannonian zone from the Permianto the Neogene, as inferred by different authors.

The results obtained from nappe systems inthe Western Carpathians are interpreted withinthis framework of deformation of the widerAlpine-Carpathian-Pannonian system, wheretectonic rotations are known to be a character-istic feature. These rotations can be simulated bya model for the entire Alpine-Carpathian-Pannonian zone and for the Western Car-pathians.

Palaeomagnetic properties of rocks fromthe Western Carpathians

All samples analysed at our laboratory weresubjected to detailed magnetic cleaning, gener-ally by thermal demagnetization using a MA-VACS system (which guarantees a highmagnetic vacuum during heating). Pilot sampleswere studied pctromagnetically to define mag-netic carriers. Account was taken of the effect oflocal tectonics on the deviation of palaeomag-netic directions, and samples were not collectedfrom highly tectonized nappes. Remanenceswere studied by multi-component analysis (Kir-schvink 1980; Kent et al. 1983; McFadden &Schmidt 1986).

Palaeomagnetic studies in the Outer Car-pathian flysch belt have focused on peliticsediments, red and grey claystones and fine-grained sandstones. These rocks display import-ant secondary components of magnetization. Inmost of these rocks, the magnetic carrier isfine-grained magnetite, with haematite beingfrequent in grey sediments. In most cases, thesampled units of the Outer Western Carpathiansexhibit anticlockwise rotations. Rocks of theteschenite association and their contact marginsrecord thermo-remanent magnetizations whichalso indicate anticlockwise rotation (References2 to 9 in Table 1).

The subhorizontal nappe of the White Car-pathians has exposures of relatively undeformedsandstones, siltstones and mudstones. Magnet-ization components from these rocks displayboth normal and reverse polarities, which aredefined with a high degree of confidence. Figure3 shows typical results of thermal demagnetiz-ation, in which hematite is the magnetic carrier.Figure 4 gives mean palaeomagnetic directionsderived by progressive thermal demagnetizationand multi-component analysis. The data aregiven in Table 1 (Reference 5, White Car-pathians, western Slovakia), after inverting

reversed polarities through the origin, and againindicate an anticlockwise tectonic rotation.

The reliability of the interpretation of tectonicrotations can be enhanced by systematic mag-netostratigraphic investigations. The magneto-stratigraphy of the Tithonian-Berriasianboundary strata has been investigated at Brodno(near Zilina, W. Slovakia), in the Klippen Belt(see Housa et al. this volume). Palaeomagneticdirections from this unit indicate large anti-clockwise tectonic rotation (Reference 10 inTable 1).

Samples from several rock complexes in theWestern Carpathians indicate syn-tectonic rem-agnetization during Alpine folding, produced bylong-lived metamorphism. The remanence of theSilica nappe (northern Hungary) has also beenattributed to this mechanism (Marton et al. 1991).Folding causes both chemical remanent magnet-ization and thermo-viscous magnetization. Atypical example is the Meliata series, whichconsists of Triassic and Jurassic radiolarian rocks,Ladinian and Carnian corneo-limestones, radio-larian rocks, grey slates and red limestones ofDogger age, and limestones (olistolites?) ofTriassic age. Magnetic carriers with relatively lowunblocking temperatures are observed, except inthe red radiolarites and corneo-limestones, inwhich hematite is the magnetic carrier. Primarypalaeomagnetic components are not preserved.For example, Fig. 5 gives the results of the meandirections of separated components of rem-anence in the temperature interval of 150-400°Cfor six sites. Similar results were obtained for theother 11 sites. Mean virtual poles for the Meliataseries show an increase in dispersion after tiltcorrection (in situ: a95 = 8.5°, к = 18.6; tiltcorrected: a95 = 13.6°, k = 7.9; N = 17). Thus, theseparated remanence components in this tem-perature interval are post-folding in age and areof secondary origin. The pole position computedfrom the in situ mean directions (paleolatitude= 46.5CW; palaeolongitude = 299.0°; a95 = 10.8°;к = 23.8) is close to the pole positions derived forCretaceous rocks in the Western Carpathians(see Table 1). All directions in the Meliata seriesare of normal polarity, suggesting that remag-netization occurred in the Cretaceous longnormal polarity epoch, which persisted from theAptian to the Santonian. The magnetization isprobably of syntectonic origin and again indicatesan anticlockwise tectonic rotation, in this case inthe period after remagnetization.

Kruczyk et al. (1992) prove pre-tectonicmagnetization components in Jurassic car-bonates from the

nappe, using magne-tomineralogical and other analyses. In contrastto the majority of data from the Western

PERMIAN-NEOGENE, WESTERN CARPATHIANS 179

Fig. 4. Stereographic projection of the mean palaeomagnetic directions for sites in the Late Senoniansandstones and claystones of the Javorina Formation, White Carpathians, western Slovakia, (a) Meandirections with the optimum Fisherian grouping during progressive thermal demagnetization; (b) meandirections derived by multi-component analysis.

Carpathians, both anticlockwise and clockwise the southernmost part of the Inner Carpathianstectonic rotations occur in different parts of this on the territory of North Hungary, anticlockwisenappe. tectonic rotation occurred in the period follow-

In the Aggtelek-Rudabanya Mountains, in ing the Triassic, probably in the Neogene

180 M. KRS ET AL.

Fig. 5. Mean directions of remanence components separated by multi-component analysis for 6 sites in theMeliata series, southern Slovakia, (a) tilt corrected results; (b) in situ results.

(Marton et al. 1988). The remanence com-ponents used in this interpretation were derivedin higher temperature intervals, show bothnormal and reverse polarities and pass a fold test(References 17-20 in Table 1).

Summary of paleolatitudes and rotations

Figure 6 presents values of palaeomagneticdeclination, inclination and palaeolatitudeplotted against age. Permian to the Early-Mid-Eocene rocks from the Western Carpathiansexperienced predominantly anticlockwise ro-tations. Lower inclination values were generallyfound, indicating that the rocks were depositedat lower paleolatitudes. Because most studiedrocks of the Western Carpathians are from theflysch formation, and so were deposited oninclined sedimentation surfaces, the magneticinclination of these rocks is weighted with anerror. The tilt of the sedimentation surfaces,however, attained only a few degrees (M. Rakusand M. Potfaj, pers. comm.). Large changes inpalaeolatitude occurred during the Permian andTriassic. Similar changes in palaeolatitude alsooccurred for the European plate in the Permianand Triassic, and were caused by the drift of theLaurasian plate (cf. Dercourt et al. 1993).

Anticlockwise rotations prevail throughoutthe Western Carpathians in Slovakia, EastMoravia and North Hungary, except in theJurassic rocks of the Krizna nappe. Up to 110°rotation occurred in the Permian rocks and the

flysch formation shows about 60° anticlockwiserotation.

Separation of components of tectonicrotation

Figure 2 shows that palaeomagnetic pole pos-itions for rocks of the same or similar age fromthe Alpine-Carpathian-Pannonian zone displayspecific distributions, indicating rotation of thewhole zone as suggested by Marton (1987),Marton & Mauritsch (1990) and Mauritsch &Becke (1987). Similar results were obtained inthe Western Carpathians (Kotasek & Krs 1965;Krs et al. 1982; Marton et al. 1991).

The scatter of poles can be explained using amodel in which movements are partitioned intotwo components: the first relating to rotation ofthe major plate to which the unit is attached(rotation about a distant rotation pole); thesecond relating to rotation during Alpine col-lision of the smaller-scale tectonic block contain-ing the unit (rotation about a proximal pole ofrotation). We computed parameters of smallcircles centred on the Western Carpathians(50°N,

These represent the loci of poles ofequal distance from the study area. Poles lyingon a certain circle may differ in declination butnot in inclination. Localised rotations withouttranslation will result in a dispersion of polesalong a small circle, whereas large-scale move-ments will also produce movement of poles fromone small circle to another. Six pole trajectories

PERMIAN-NEOGENE, WESTERN CARPATHIANS 181

Fig. 7. Model distribution of pole positionscalculated for rocks with different values ofinclination = -15°, 0°, 15°, 30°, 45° and 60°, roughlycorresponding to the time span from the Permian tothe Neogene. Solid (dashed) lines and solid (open)symbols indicate projection onto the upper (lower)hemisphere.

were calculated (Fig. 7), with inclinations corre-sponding to -15°, 0°, 15°, 30°, 45° and 60°. Thisrange of inclinations corresponds to that ob-served from the Permian to the youngest rocksstudied.

Figure 8 shows pole positions for Permianrocks of the Inner Carpathians relative to polepositions from Permian rocks in other parts ofthe Alpine-Carpathian-Pannonian zone. Thisindicates a translation of Permian rocks fromequatorial and subequatorial zones, and also arotation of nappes resulting from Alpine col-lision. Figure 9 shows pole positions derivedfrom Jurassic carbonates from the Krizna nappe(References 11 to 16, Table 1) and a poleposition derived from the Tithonian-Berriasianboundary at Brodno, near Zilina (Reference 10,Table 1). Although of widely different position,poles from both areas approach the theoreticaltrajectory for inclination = 45°, indicating theinfluence of vertical axis rotation. Kruczyk et al.(1992) suggested this difference results fromoroclinal bending of the Inner Western Car-pathians. Though seemingly anomalous, thepole position derived in the Tithonian-Berria-sian carbonates adheres to the path for Jurassic

182 M. KRS ET AL.

Fig. 8. Distribution of pole positions obtained fromPermian rocks in the Tnner Western Carpathians(IWC), the region of Villany (VIL), the SouthernAlps (SAL), NW Slavonia (NWS), the NorthernApennines (NAP) and the Eastern Alps (EAL).Solid (dashed) lines and solid (open) symbols indicateprojection onto the upper (lower) hemisphere.

Fig. 9. Distribution of pole positions obtained fromJurassic carbonates from the Krizna nappe system(Reference 11-16, Table 1) and inTithonian-Berriasian limestones at the locality of Brodno, nearZilina (Reference 10, Table 1). Solid (dashed) lineindicates theoretical distribution of pole positions forrocks with inclination = 45°.

rocks, and indicates a distinct anticlockwisetectonic rotation with respect to the Kriznanappe. Similar rotation has been deduced fromanother magnetostratigraphic profile across

Fig. 10. Distribution of pole positions obtained fromEarly Triassic carbonates from the Aggtelek-Rudabanya Mountains. Solid (dashed) line indicatestheoretical distribution of pole positions for rockswith inclination = 30°.

Tithonian-Berriasian carbonates at Stramberk,North Moravia (Outer Western Carpathians).

This analysis suggests tectonic rotation on thescale of entire nappe systems. To judge thepossibility of tectonic rotations within a smallerarea, virtual pole positions were calculated fortwo areas, and their distributions compared withthe modelled small circles. The data of Marton etal. (1988) were used to compute virtual polepositions for Early Triassic carbonates of theAggtelek Mountains. These poles lie close to thesmall circle corresponding to inclination = 30°,and are distributed along the circle as a result ofsmall-scale tectonic rotations (Fig. 10). Simi-larly, virtual pole positions for Late Senonianrocks of the White Carpathians (Reference 5,Table 1) show a distribution which also suggestssignificant small-scale tectonic rotations (Fig.11), even within the single sampled nappe whichcontains subhorizontal beds.

Conclusions

The palaeomagnetic data from the WesternCarpathians indicate a marked tectonic rotationof larger rock units, predominantly in ananticlockwise sense. These rotations arc ob-served in the rocks of the Inner Carpathians, theKlippen Belt, and the Outer Carpathian flyschbelt. Tectonic rotations lead to the formation ofa specific pole distribution which runs across theapparent polar wander path (in this case for theAfrican plate). A similar distribution also occurs

PERMIAN-NEOGENE, WESTERN CARPATHIANS 183

Fig. 11. Distribution of pole positions observed inLate Senonian sediments from the WhiteCarpathians, western Slovakia, within subhorizontalbeds in the same nappe. The mean pole position forthis nappe is given under Reference 5 in Table 1.Solid (dashed) line indicates theoretical distributionof pole positions for rocks with inclination = 45°.

in the West European and Central EuropeanHercynian belt (Edel 1987; Krs et al. 1995). Inthe Western Carpathians, tectonic rotationsoccur on a range of scales, from those affectingthe whole region to those affecting singlenappes/parts of nappes.

The most pronounced palaeolatitudinal driftoccurred in the Permian and Triassic, and thedrift began decelerating from the Jurassic untilthe Neogenc (Fig. 6). Similar variations havebeen established for other regions of theTethyan realm, e.g. the Iberian Mescta andadjacent mobile belts, Corsica and Sardinia,Italy including Sicily and the adjacent parts ofthe Alps, Greece and Southern Bulgaria, theTransdanubian Mountains in Hungary, andTurkey including the eastern Aegean territoryand Cyprus (Van der Voo 1993).

Rotations of individual fault blocks inducelarge scatters of palaeomagnetic pole positionseven though they may affect only small units. Incontrast, changes in pole positions due to drift oflarger units are generally smaller, though thetranslations involved are appreciable. For in-stance, for the Permian rocks of the WesternCarpathians these translations reach values of upto 6000 km since the Permian to the present time.These differencesin the magnitude of pole move-ments reflect two different types of rotation, i.e.those around rotation poles close to and farremoved from the study area, respectively.

The authors wish to thank A. Morris for reviewing thepaper, for help in preparation and editing the finalversion of the paper, and for improvement of theEnglish. They are also grateful to E. Marton and D.Peacock for reviews and helpful suggestions.

References

DERCOURT, J., RICOU, L. E. & VRIELYNCK, B. (eds)

1993. Atlas, Tethys, Palaeoenvironmental maps,explanatory notes. CCGM, CGMW, Paris.

EDEL, J. B. 1987. Paleopositions of the westernEurope Hercynides during the Late Carbonifer-ous deduced from paleomagnetic data: conse-quences for "stable" Europe. Tectonophysics,139,31-41.

HOUSA, V., K R S . M . , KRSOVA, M. & P R U N E R , P . 1996.

Magnetostratigraphy of Jurassic-CretaceousLimestones in the Western Carpathians. Thisvolume.

IRVING , E., TANCZYK , E. & HASTI E , J. 1976. Catalogue

of paleomagnetic directions and poles. Energy,Mines and Resources, Ottawa. GeomagneticSeries Number 6, 10, 1-70.

KENT, J. Т., BRIDEN, J. С & MARDIA, K. V. 1983.

Linear and planar structure in ordered multiva-riate data as applied to progressive demagnetiz-ation of palaeomagnetic remanence. GeophysicalJournal of the Royal Astronomical Society, 75,593-621.

KIRSCTIVTNK, J. L. 1980. The least-squares line andplane and the analysis of palaeomagnetic data.Geophysical Journal of the Royal AstronomicalSociety, 62,699-718.

KORAB, Т., KRS, M., KRSOVA, M. & PAGAC, P. 1981.

Palaeomagnetic investigations of Albian(?)-Paleocene to Lower Oligocene sedimentsfrom the Dukla unit, East Slovakian Flysch,Czechoslovakia. Zapadne Karpaty, seria geolo-gia, Geological Institute of Dionyz Stur, Brati-slava, 7. 127-149.

KOTASEK, J. & KRS, M. 1965. Palaeomagnetic study oftectonic rotation in the Carpathian Mountains ofCzechoslovakia. Palaeogeography, Palaeoclima-tology, Palaeoecology, 1,39-19.

KRS, M. 1966. Palaeomagnetic pole position for theLower Triassic of East Slovakia (Czechoslo-vakia). Vestnik, Geological Survey, Prague, XLI,4, 287-290.

1982. Implication of statistical evaluation ofPhanerozoic palaeomagnetic data (Eurasia,Africa). Rozpravy CSAV, fada matematickych apflrodnich ved, Academia, Prague, 92, 3, 1-86.

& SMI'D, B. 1979. Palaeomagnetism of Cre-taceous rocks of the teschenite association, OuterWest Carpathians of Czechoslovakia. AppliedGeophysics, Prague, Journal of Geological Sci-ences, 16,7-25., KRSOVA, M., CHVOJKA, R. & POTFAJ, M. 1991.

Paleomagnetic investigations of the flysch belt inthe Orava region, Magura unit, CzechoslovakWestern Carpathians. Geologicke prace, Geo-logical Institute of Dionyz Stur, Bratislava, 92,135-151.

184 M. KRS ET AL.

, & PRUNER, P. 1995. Palaeomagnetismand palaeography of Variscan formations of theBohemian Massif: a comparison with otherregions in Europe. Studia geophysica et geodae-tica, Academia, Prague, 39, 309-319., , , CHVOJKA, R. & POTFAJ, M.

1993. Palaeomagnetic investigations in the BieleKarpaty Mountains unit, Flysch Belt of theWestern Carpathians. Geologica Carpathica,Bratislava, 45, 35^t3., & ROTH, Z. 1977. A palaeomagnetic studyof Cenomanian-Lower Turonian sediments in theMoravskoslezske Beskydy Mountains. Vestnik,Geological Survey, Prague, 52,323-332., MUSKA, P. & PAG Ac, P. 1982. Review ofpalaeomagnetic investigations in the West Car-pathians of Czechoslovakia. Geologicke prace,Spravy, Geological Institute of Dionyz Stur,Bratislava, 78, 39-58., PRUNER, P. & ROTH, Z. 1978. Palaeotectonics

and palaeomagnetism of Cretaceous rocks of theOuter West Carpathians of Czechoslovakia. Geo-fyzikalni sbornik CSAV Prague, XXVI, 512,269-291.

KRUCZYK, J., KADZIALKO-HOFMOKL, M., LEFELD, J.,

PAGAC, P. & TUNYI, I. 1992. Paleomagnetism of

Jurassic sediments as evidence of oroclinal bend-ing of the Inner West Carpathians. Tectono-physics, 206,315-324.

MARTON, E. 1987. Paleomagnetism and tectonics inthe Mediterranean region. Journal of Geody-namics, 7, 33-57., MARTON, P. & LESS, G. 1988. Palaeomagnetic

evidence of tectonic rotations in the southern

margin of the Inner West Carpathians. Physics ofthe Earth and Planetary Interiors, 52, 256-266.& MAURITSCH, H. J. 1990. Structural applications

and discussion of a paleomagnetic post-Paleozoicdata-base for the Central Mediterranean. Physicsof the Earth and Planetary Interiors, 62, 48-59., & TARLING, D. H. 1987. Pre-Alpinepaleomagnetic results of the Alpine-Mediter-ranean belt. In: FLUGEL, SASSI & GRECULA (eds)

Pre-Variscan and Variscan events in the Alpine-Mediterranean mountain belts. Mineralia SlovacaMonograph, Bratislava, 351-360.

MARTON, P., ROZLOZNIK, L. & SASVARI, T. 1991.

Implications of a palaeomagnetic study of theSilica nappe, Slovakia. Geophysical Journal Inter-national, 107, 67-75.

MAURITSCH, H. J. & BECKE, M. 1987. Paleomagnetic

investigations in the Eastern Alps and theSouthern border zone. In: FLUGEL, H. W. &FAUPL, P. (eds) Geodynamics of the Eastern Alps.Vienna, 282-308.

MCFADDEN, P. L. & SCHMIDT, P. W. 1986. The

accumulation of palaeomagnetic results frommulti-component analysis. Geophysical Journalof the Royal Astronomical Society, 86, 965-979.

PATRASCU, S., BLEAHU, M. & PANAIOTU, С 1990.

Tectonic implications of paleomagnetic researchinto Upper Cretaceous magmatic rocks in theApuseni Mountains, Romania. Tectonophysics,180,309-322.

VAN DER VOO, R. 1993. Paleomagnetism of theAtlantic, Tethys and Iapetus Oceans. CambridgeUniversity Press.