Post-IR IRSL dating the oldest (?) river terrace sediments in the Polish Outer Carpathians: Insights into the landscape evolution

Abstract

Post-infrared infrared stimulated luminescence (post-IR IRSL or pIRIR) was applied to determine the age of the highest-elevated alluvial sediments in the Polish Outer Carpathians. These sediments are preserved on the western slope of the Dunajec River valley, and are located 150–155 m above the present-day river channel. So far, they have been interpreted as accumulated during the Praetiglian (2.58–2.40 Ma). The pIRIR ages, however, indicate that the sediments were deposited ~2 Ma later. Such results incorporate an important record of river system evolution which has been developing very dynamically since the time of the sediment accommodation. The determined ages introduce average rate of river incision which can be calculated as 0.48–0.50 mm a−1 since the last ~309 ka. This implies that the river section has been fairly tectonically uplifting and brings attention to the rates of uplift in the rest part of the Polish Outer Carpathians. Also, adopting results from the former dating campaign, it is clear that relics of Pleistocene alluvial sediments are predominantly of cold-climate origin, and a scenario for this style of sediment preservation is proposed.