Enhancing the reliability of the magnetostratigraphic age assignment of azimuthally nonoriented drill cores by the integrated application of palaeomagnetic analysis, field tests, anisotropy of magnetic susceptibility, and the evolution of the endemic fauna as documented on the upper Miocene limnic deposits of the Turiec Basin (Western Carpathians)

This study aimed at the magnetostratigraphic age assignment of a 100-m-long drill core penetrating the Miocene lake sediments of the intramontane Turiec Basin of the Inner Western Carpathians and obtaining paleomagnetic constraints for the orientation of the basin during its development. Concerning the azimuthally nonoriented drill core, we documented first the consistency of the paleomagnetic signals, residing mostly in greigite, within "pilot" core segments, thus satisfying the minimum requirement for primary/ early diagenetic magnetization. Next, all core segments were oriented with respect to each other by the means of silt intercalations in the mudstone and/or anisotropy of magnetic susceptibility foliation planes. The result was a remarkable clustering of the paleomagnetic vectors. Finally, we proved the suitability of the drill core for magnetostratigraphic purpose with positive inclination only, conglomerate, and regional tilt tests. The latter included the azimuthally fully restored paleomagnetic locality mean direction for the core (fitting the bedding azimuth of the drill core to the one measured close to the drill site) and several geographically distributed localities in the Turiec Basin. Because the drill core was magnetized during a fairly long normal polarity interval, the age of deposition was estimated as 7.7-8.1 Ma, corresponding to chron C4n.2n, taking into consideration also the position of the drill core to a dated volcanic horizon and the gradual intralacustrine evolution of the endemic ostracode fauna. Concerning the orientation of the basin during deposition of the studied sediments, we concluded that they were deposited after the large-scale counterclockwise Miocene rotation of the Western Carpathians.