Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar (Eifel, Germany)

Abstract

The study presents the results of a heavy mineral analysis from a 38m long record of lacustrine Eifel maar sediments from a core section of the Dehner dry maar. The record encompasses the period from 29,000 to about 12,500 b2k. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size Index (GSI and CSI). The results indicate that during the early stages of MIS2 (39 to 30m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by low GSI and CSI ratios resulting from a reduced mobility of material due to a vegetation cover. The period between 23,000 and 12,900 b2k is characterized by a higher supply of heavy minerals from regional and more distant sources. Changes in the provenance areas are indicated in inverse relationships between zircon, rutile, tourmaline (ZRT) and carbonate particles. Shifts in the wind direction are documented in pronounced peaks of carbonate particles indicating easterly winds that have crossed the limestone basins in the Eifeler North South Zone. ZRT-group minerals on the other hand suggest a westerly source area from Palaeozoic clastic sedimentary rocks. The heavy mineral assemblage of the LGM section at 23,000 to 15,000 b2k displays a close correspondence with the stratigraphic relationships that have been obtained for the Landscape Evolution Zone 4 of the ELSA-Vegetation Stack of Sirocko et al. (2016). From the Heinrich 2 event onwards the analyses indicate an increasing degree of mixing of heavy minerals from various provinces. This suggests the existence of a presumably incomplete, thin cover of deflated loess-like sediments that has been repeatedly reworked on the elevated surfaces of the Eifel.