Geomorphological record and equilibrium line altitude of glaciers during the last glacial maximum in the Rodna Mountains (eastern Carpathians)

Abstract

In the eastern Carpathians the legacy of glaciation is preserved in several isolated mountain massifs. This paper presents new mapping results of glaciated valley land systems in the Rodna Mountains, the highest part of the eastern Carpathians (2303 m above seal level). In most of the glacial valleys, the maximal Pleistocene extent is marked by freshly shaped moraines, which are referred in this study as the Pietroasa glacial stage and regarded as the last glacial maximum (LGM) advance. Only in three valleys do older Şesura glacial stage moraines (pre-LGM, likely Marine Oxygen Isotope Stage 6) occur. On the basis of the geomorphological record, we reconstruct the extent, surface geometry, and equilibrium line altitude (ELA) of Pietroasa-stage glaciers. The local ELA pattern of north-exposed glaciers in the Rodna Mountains shows a rising trend towards the southeast, which suggests dominant snow-bearing winds and orographically induced precipitation from the west. This finding fits well with the dominant palaeo-wind direction inferred from other Carpathian proxies and confirms the dominance of zonal circulation pattern during the global LGM in central eastern Europe.

Past glaciation of temperate‐continental mountains: A model for a debris‐charged plateau icefield/cirque glacier landsystem in the Southern Carpathians, Romania

“…Likewise, the debris-rich cirque glacier component of the landsystem is not dissimilar to that of the majority of former cirque and valley glaciers in all the Romanian Carpathians (Urdea et al, 2022a(Urdea et al, , 2022b(Urdea et al, , 2022c(Urdea et al, , 2022dUrdea et al, 2022) and the Western Carpathians (e.g., Tatra Mountains) (Zasadni, Kłapyta, Kałuża, & Makos, 2022;Zasadni et al, 2022aZasadni et al, , 2022bZasadni et al, , 2022cZasadni, Kłapyta, Tołoczko-Pasek, & Makos, 2022;. Indeed, previous research in the Romanian Carpathians highlighted a glacial geomorphology throughout the last deglaciation that was characterised by debris-charged palaeoglaciers (e.g., Balaban, 2018;Gheorghiu, 2012;Gheorghiu et al, 2015;Kłapyta et al, 2021Kłapyta et al, , 2022Lászl o et al, 2013;Reuther et al, 2007;Ruszkiczay-Rüdiger et al, 2016, 2021, but the exact timing and causes of glacial recession have not been assessed in detail . Consequently, there is a need to apply a landsystem approach to geomorphological mapping and couple it with radiometric dating programmes and numerical ice models to enable robust comparisons of spatio-temporal changes in glaciation style across a wider region.…”

“…The most recent studies consider an alpine (glacial, periglacial and paraglacial) geomorphological model as a framework for palaeoglaciation and palaeoclimate reconstruction. This has either focused on applying absolute/relative dating methods and/or numerical ice modelling (Balaban, 2018;Gheorghiu, 2012;Gheorghiu et al, 2015;Ignéczi & Nagy, 2016;Kłapyta et al, 2021Kłapyta et al, , 2022Kuhlemann, Dobre, et al, 2013;Lászl o et al, 2013;Reuther et al, 2007;Ruszkiczay-Rüdiger et al, 2016, 2021Tîrl a et al, 2020;Urdea & Reuther, 2009), or conducting quantitative inventories of landform characteristics (Gunnell et al, 2022;Mîndrescu & Evans, 2014Mîndrescu et al, 2010;Necs ¸oiu et al, 2016;Onaca et al, 2013;Popescu, 2018;Popescu et al, 2021;Popescu, Onaca, Urdea & Vespremeanu-Stroe, 2017;Șerban et al, 2019;Vasile et al, 2022;Vespremeanu-Stroe et al, 2012). Despite this work, the relationships between palaeoclimate, geomorphology, and glaciation style and dynamics, particularly in a mountain landsystem context, remain poorly understood.…”

Equilibrium line altitudes of alpine glaciers suggest summers in Alaska were not more than −2 – −5 °C colder than the pre-Industrial during the Last Glacial Maximum

“…Alpine glaciers are robust indicators of climate as their extent is primarily controlled by summer temperatures and annual precipitation (Ohmura et al, 1992;Ohmura and Boettcher, 2018;Kurowski, 1891;Benn and Lehmkuhl, 2000;Sutherland, 1984;Walcott, 2022;Rupper and Roe, 2008;Roe et al, 2017). Numerous studies have compared ELAs of reconstructed LGM glaciers worldwide to ELAs of extant glaciers (e.g., Kłapyta et al, 2021), ELAs of reconstructed LIA glaciers (Federici et al, 2008), or hypothetical ELAs in the atmosphere (Ono et al, 2005) and used atmospheric lapse rates to estimate LGM temperature depressions. Additionally, several numerical models of alpine paleoglaciers have been developed that quantify paleo-temperature andprecipitation conditions.…”