(Un)Resolved contradictions in the Late Pleistocene glacial chronology of the Southern Carpathians - new samples and recalculated cosmogenic radionuclide age estimates

Abstract

Application of cosmogenic nuclides in the study of Quaternary glaciations has increased rapidly during the last decade owing to the previous absence of direct dating methods of glacial landforms and sediments. Although several hundred publications have already been released on exposure age dating of glacial landforms worldwide, very few studies targeted the Carpathians so far (Kuhlemann et al, 2013a; Makos et al., 2014; Reuther et al, 2004, 2007; Rinterknecht et al. 2012).

There are many unresolved or contradictory issues regarding the glacial chronology of the Romanian Carpathians. Recently, some attempts have been made to develop an improved temporal framework for the glaciations of the region using cosmogenic ¹⁰Be dating (Reuther et al. 2004, 2007, Kuhlemann et al. 2013a). However, these studies made the picture even more confusing because the local last glacial maximum, for instance, apparently occurred in asynchronous timing compared to each other and also to other dated glacial events in Europe (Hughes et al, 2013).

This situation is even more interesting if we take into account that the local glacial maximum tends to agree with the global LGM derived from the Eastern Balkans (Kuhlemann et al. 2013b), while the penultimate glaciation seems to significantly overtake the LGM advance over the Western Balkans (Hughes et al. 2011).

The primary candidate reasons to resolve these discrepancies are methodological, e.g. insufficient number of samples (one sample/landform) ignoring geological scatter of the data and the application of different half-lives, production rates and scaling schemes during the calculation of exposure ages. Systematic methodological uncertainties in computing exposure ages from measured nuclide concentrations have a significant impact on the conclusions concerning correlations of exposure-dated glacier chronologies with millennial scale climate changes (Balco, 2011). The changes in glacial timing generated by only using the most recent constants for the exposure age calculations has not been considered in the most recent review on the timing of the LGM (Hughes et al., 2013).

Main objective of our study is to utilize the potential offered by the cosmogenic in situ produced ¹⁰Be dating to disentangle the contradictions in the available Southern Carpathian Late Pleistocene glacial chronology (Kuhlemann et al, 2013a; Reuther et al, 2004, 2007). We recalculate ¹⁰Be data published by Reuther et al. (2007) in accordance with the new half-life and production rate of ¹⁰Be. Besides, a new sample set has been collected to establish a precise chronological framework supported by in-situ exposure dating of several additional moraine generations.