科研之友
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摘要
Deep-seated gravitational slope deformations (DSGSDs) with characteristic sackung landforms (e.g., double crests, trenches, uphill-facing scarps, and toe bulging) are considered by some researchers to be diagnostic features indicating past mountain glaciations. However, an extensive literature review on sackung features throughout the world reveals that in some regions, paraglacial processes are not the causes of such phenomena. Sackungen occur across a diverse spectrum of mountain types, with different morphoclimatic histories, including regions that have never experienced glaciation. To reinforce that sackungen may originate independently of glaciation, we also include two case studies from the Western Carpathians (Czech Republic and Slovakia) which are supported by detailed geomorphic mapping, trenching and absolute dating (Be-10, C-14 and OSL). On the Ondrejnik ridge (Outer Western Carpathians, Czech Republic), sackungen occur in the mid-Holocene in the medium-high mountains which are beyond the Pleistocene glacial limits. On the Salatin Mt. (Tatra Mts., Slovakia), the sackungen, which occur in formerly glaciated terrain, date between similar to 7.5 and 4.2 ka BP, representing a >4 ka time lag after the disappearance of glaciers. This suggests that the direct link between the ice retreat and the onset of sackung formation is not obvious, even in the case of the once glaciated mountain range. Although paraglacial stress release is undoubtedly one of the crucial causes of sackung genesis, in many mountain regions, it is not the only important mechanism. Therefore, despite occurring in numerous (de)glaciated mountains, sackung features cannot be considered as proof of past mountain glaciations, e.g., during analysis of extraterrestrial settings.
- 出版日期2015-11-1
