科研之友
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摘要
A detailed rock magnetic analysis of the last glacial/interglacial loess-palaeosol sequences was carried out in the framework of a comprehensive stratigraphic study of loess in Saxony (Eastern Germany). Magnetic susceptibility and laboratory-induced remanences have been determined to compare individual sections and to identify the specific rock magnetic characteristics of the Saxonian Loess Province. According to the model of pedogenic magnetic enhancement, an increasing neoformation of ferrimagnetic minerals in the course of pedogenesis was observed only in the uppermost Late Weichselian lithological units consisting of pure aeolian loess and indicating dryer climatic conditions. In contrast, the rock magnetic characteristics of the lower Middle and Early Weichselian units exhibit a significant destruction of primary magnetic minerals caused by such secondary processes as climatically controlled waterlogging and reworking. This change in magnetic composition with stratigraphic depth was additionally proved by factor analysis in which the main observation, an increasing chi(fd) with decreasing chi, argues for a general magnetic depletion in conjunction with decreasing magnetic grain sizes caused by weathering of larger primary particles. The magnetic fingerprint of the Saxonian loess is characterised by prevailing magnetic depletion processes, which effectively rules out the application of the wind vigour model. Moreover, the magnetic characteristics differ significantly from that of other loess regions and support a new and independent model, which explains the magnetic behaviour of strongly reworked and waterlogged (gleyed) loess-palaeosol sequences in the relatively humid Central European periglacial areas.
- 出版日期2013-5-16
