Abstract
Abstract. Periglacial features, such as various kinds of patterned ground, cryoturbations, frost wedges, solifluction structures, and blockfields, are among the most common relics of cold climate periods, which repetitively occurred throughout the Quaternary. As such, they are widespread archives of past environmental conditions. Climate controls on the development of most periglacial features, however, remain poorly known, and thus empirical palaeo-climate reconstructions based on them have limited validity. This study presents and evaluates a simple new inverse modelling scheme called PERICLIMv1.0 (PERIglacial CLIMate) that derives palaeo-air temperature characteristics related to the palaeo-active-layer thickness, which can be recognized using many relict periglacial features found in past permafrost regions. The evaluation against modern temperature records showed that the model reproduces air temperature characteristics with average errors ≤1.3 ∘C. The past mean annual air temperature modelled experimentally for two sites in the Czech Republic hosting relict cryoturbation structures was between -7.0±1.9 and -3.2±1.5 ∘C, which is well in line with earlier reconstructions utilizing various palaeo-archives. These initial results are promising and suggest that the model could become a useful tool for reconstructing Quaternary palaeo-environments across vast areas of mid-latitudes and low latitudes where relict periglacial assemblages frequently occur, but their full potential remains to be exploited.
Highlights
Many mid- and low-latitude regions of the world host a number of distinctive landforms and subsurface structures collectively termed relict periglacial features, such as various kinds of patterned ground, cryoturbations, frost wedges, solifluction structures, and blockfields, which developed during cold periods of the Quaternary due to intense freeze– thaw activity taking place under seasonal frost or permafrost conditions
This situation can be largely attributed to prevailing interest in mapping the distribution patterns of periglacial features and their associations with mean annual air temperature (MAAT), which has been characteristic for traditional palaeo-periglacial geomorphology, while other details on their surface and subsurface dimensions have been widely overlooked
This study presents and evaluates a simple modelling scheme called PERICLIMv1.0 (PERIglacial CLIMate) that is designed to infer palaeo-air temperature characteristics associated with relict periglacial features indicative of the palaeo-active-layer thickness, and the study discusses its uncertainties and applicability with respect to other palaeoproxy records and/or model products
Summary
Many mid- and low-latitude regions of the world host a number of distinctive landforms and subsurface structures collectively termed relict periglacial features, such as various kinds of patterned ground, cryoturbations, frost wedges, solifluction structures, and blockfields, which developed during cold periods of the Quaternary due to intense freeze– thaw activity taking place under seasonal frost or permafrost conditions. Periglacial features form through various thermally induced and gravity-induced processes that mostly operate within a layer of seasonal freezing and thawing, the base of which is commonly sharply defined and confines the subsurface dimensions of the features (Williams, 1961) This zone is usually discernible in vertical cross sections because intense ice segregation and mass displacements associated with the formation of periglacial features alter the freeze–thaw layer so that its composition and properties differ from those of the underlying ground. This study presents and evaluates a simple modelling scheme called PERICLIMv1.0 (PERIglacial CLIMate) that is designed to infer palaeo-air temperature characteristics associated with relict periglacial features indicative of the palaeo-active-layer thickness, and the study discusses its uncertainties and applicability with respect to other palaeoproxy records and/or model products It targets palaeo-active-layer phenomena because their palaeoenvironmental significance and preservation potential are substantially higher than for seasonal frost features. It intends to stimulate the application of modelling tools and foster the development of new quantitative methods in palaeo-environmental reconstructions utilizing relict periglacial features in order to improve their reputation as palaeo-proxy indicators
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