Aherwar K., Šujan M., Chyba A., Rózsová B. & Aster Team, 2024: Authigenic ¹⁰Be/⁹Be dating of the Horná Štubňa river terrace points to the inception of the terrace staircase formation in the Turiec Basin (Slovakia) from the Middle Pleistocene transition. Acta Geologica Slovaca, 16, 1, 33–44.

Authigenic ¹⁰Be/⁹Be dating of the Horná Štubňa river terrace points to the inception of the terrace staircase formation in the Turiec Basin (Slovakia) from the Middle Pleistocene transition

Kishan Aherwar¹, Michal Šujan^1,2, Andrej Chyba³, Barbara Rózsová¹ & Aster Team^4*

¹Department of Geology and Paleontology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15 Bratislava, Slovakia; aherwar1@uniba.sk
²Laboratory of Quaternary Research, State Research Institute Nature Research Centre, 2 Akademijos Str., LT-08412, Vilnius, Lithuania, michal.sujan@gamtc.lt
³Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38 Bratislava, Slovakia; Andrej.chyba@savba.sk
⁴CNRS-IRD-Collège de France-INRA, CEREGE, Aix-Marseille Univ., 13545 Aix-en-Provence, France; aumaitre@cerege.fr

* - Georges Aumaître, Karim Keddadouche, Fawzi Zaidi

Abstract

Despite the extensive presence of river terraces in the Central Western Carpathians, geochronological proxies for their formation are scarce, particularly concerning Middle and Lower Pleistocene accumulations. This study employs authigenic ¹⁰Be/⁹Be dating on a Horná Štubňa river terrace outcrop in the southern Turiec Basin, with an expected age of > 500 ka, as the settings prohibit the use of other, more established methods. The dating focused on floodplain muds, situated above angular gravels deposited by the debris flow process and below rounded sandy gravel deposited by a debris flood. Five ages were obtained, showing a scattered distribution ranging from 724–394 ka, after excluding one outlier sample. However, correcting the dating, which involved considering the age and uncertainty of the initial ¹⁰Be/⁹Be ratio calibration site Veľký Čepčín, resulted in an age range of 690–1020 ka, with a mean weighted age of 838.0 ± 83.3 ka. These findings suggest that the climatic changes associated with the Middle Pleistocene transition may have influenced base-level changes in the Turiec Basin, as the studied terrace represents the second-highest level of the preserved staircase. The documented low incision rate of ~ 0.03–0.04 mm·a^-1 deviates from an order of magnitude higher values determined from the Outer Western Carpathians but agrees with the values established for the Pannonian Basin, Transdanubian Range and Eastern Alps.

Key words: Western Carpathians, Quaternary, fluvial sediment, intramontane basin, cosmogenic nuclides

Manuscript received: 2024-04-30

Revised version accepted: 2024-06-17