MAGNETOSTRATIGRAPHIC AND MICROPALEONTOLOGICAL INVESTIGATIONS ALONG THE JURASSIC/CRETACEOUS BOUNDARY STRATA, BRODNO NEAR ZILINA (WESTERN SLOVAKIA)

Year, pages: 1996, 135 - 151

Results of micropaleontological and magnetostratigraphic investigations concern the determination of the Jurassic/Cretaceous (Tithonian/Berriasian) boundary at the locality of Brodno near Zilina, Western Slovakia. These studies were preceded by petromagnetic and paleomagnetic investigations of pilot samples, collected from five localities in the Western Carpathians, in N. Moravia and W. Slovakia, namely Stramberk, quarry "Kotouc"; Stramberk, quarry "Skalka"; Brodno near Zilina, abondoned quarry; Strazovce, section along a road; Hlboc near Smolenice, outcrop in a forest. All of the above mentioned localities were found suitable for magnetostratigraphic investigations, but the locality Brodno was given preference due to its suitable geological and paleontological conditions. A detailed micropaleontological study was carried out along a renumbered strata sequence in reference to previously established numbering by Michalik et al. (1990). The base of the standard zone with Calpionella, the Jurassic/Cretaceous boundary, was placed between the newly numbered beds BC-15A and BC-15B. (Fig. 2 shows the new numbering and also indicates the correlation with the previous one). Sedimentation in a quiet basin was one of the basic pre-requisites for reliable derivation of high-resolution magnetostratigraphic data. The pattern of normal and reverse polarity magnetozones from M 17 to M 21 correlates well with data derived in the regions of Foza (north Italy), Bosso Valley (Umbria, central Italy) and with marine M (Mesozoic) anomalies. A very narrow reverse sub-zone was found in the younger part of the magnetozone M 19n well correlating with a similar sub-zone derived from marine magnetic M anomalies. The base of the standard Calpionella Zone, i.e. the Jurassic/Cretaceous boundary, was placed in the younger part of the older half of the magnetozone M 19n. The base of the standard Crassicolaria Zone lies approximately in the middle of the magnetozone M 20n in the Brodno section.

Housa, V., Krs, M., Krsova, M., Pruner, P. 1996. MAGNETOSTRATIGRAPHIC AND MICROPALEONTOLOGICAL INVESTIGATIONS ALONG THE JURASSIC/CRETACEOUS BOUNDARY STRATA, BRODNO NEAR ZILINA (WESTERN SLOVAKIA). In Geologica Carpathica, vol. 47, no.3, pp. 135-151. 1335-0552.

Housa, V., Krs, M., Krsova, M., Pruner, P. (1996). MAGNETOSTRATIGRAPHIC AND MICROPALEONTOLOGICAL INVESTIGATIONS ALONG THE JURASSIC/CRETACEOUS BOUNDARY STRATA, BRODNO NEAR ZILINA (WESTERN SLOVAKIA). Geologica Carpathica, 47(3), 135-151. 1335-0552.