Permafrost or seasonal frost? A review of paleoclimate proxies of the last glacial cycle in the East Central European lowlands

摘要

Our critical revision of the sedimentological characteristics and genetic interpretation of relict periglacial soil deformation features (cryoturbations and sand wedges) suggests that the continuous permafrost zone did not necessarily reached the lowland areas of the Pannonian Basin, as suggested by previous studies. The discontinuous permafrost zone most probably penetrated the north-western part of the study area for a certain period, but most of the lowlands might have been affected only by sporadic/isolated permafrost and/or deep seasonal frost. The re-evaluated climate conditions implied by the periglacial soil structures and other proxies for a periglacial environment of the area do not constrain such a narrow zone of extremely low mean annual air temperature (MAAT) and mean annual precipitation (MAP). The compilation of the climate thresholds suggested by the observed and revised interpretation cryoturbation features and thermal contraction cracks with other paleoclimate proxies converge on 0 +/- 2 degrees C MAAT and 300-490 mm MAP on the lowland areas of the Pannonian Basin during the coldest phase of the last glacial. These values indicate a temperature drop of congruent to 10 +/- 2 C degrees and a precipitation decrease of 30-50% relative to modern conditions. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.