Teťák, F., Korábová, K. & Laurinc, D., 2025: Alternative interpretation of the Bystrica Unit in Klanečnica KLK-1 borehole (Magura Nappe) [Alternatívna interpretácia bystrickej jednotky vo vrte KLK-1 Klanečnica (magurský príkrov)]. Mineralia Slovaca, 57, 1, 81 – 96.
DOI: https://doi.org/10.56623/ms.2025.57.1.5
Abstract: In 1986, the KLK-1 (Klanečnica) borehole was drilled northwest of Moravské Lieskové as part of a regional oil and gas exploration programme. The well reached a total depth of 662 m and was intended to verify the occurrence and potential accumulation of hydrocarbons within the Drietoma anticline, a geophysically indicated structural high in the St. Hrozenkov–Drietoma area. The drilled succession was originally assigned to the Svodnice Fm. of the Biele Karpaty Unit down to 75 m, and to the Zlín Fm. of the Rača Unit below this depth. However, a re-examination of the preserved core material suggests that the presence of glauconitic sandstones and an inferred middle to late? Eocene age do not support the previous correlation with the Rača Unit. The lower interval of the borehole, below approximately 90 m, is here reinterpreted as belonging to the Bystrica Mb. of the Bystrica Unit. The borehole cores reinterpretation is supported by the abundant occurrence of larger foraminifera, lithologically variable quartz-glauconitic sandstones, and thick beds of dark grey silty claystones to marlstones, all characteristics also of the Bystrica Mb. Furthermore, the western extent of the Bystrica Unit does not appear to terminate at the Nezdenice Faults, as previously supposed, but continues westwards beneath the Biele Karpaty Unit, albeit to a limited subsurface extent.
Key words: Bystrica Mb., Vsetín Mb., Magura Nappe, Flysch Belt, borehole, structural high, hydrocarbon exploration