Preliminary Results: Magnetic Bulk Properties and Anisotropy of the Dolni Vestonice (Czech Republic) Loess-Paleosol Sequence

The present study stems from past and ongoing (ANR ACTES project) multi-disciplinary collaborative research project aimed at studying abrupt climate changes in terrestrial European eolian records for which the objectives are motivated by the following overarching questions: What can we learn from eolian records about the dynamics and the length scale of patterns of atmospheric circulation? Are there any mechanisms linking the sedimentation of dust over Greenland and in Europe during the Last Glacial Maximum? Previous investigationsof west European loess sequence revealed two main periods of increased loess deposition since the last interglacial (MIS 5) centered around 60 ± 5 kyr and 23 ± 8 kyr BP, and separated by a period with strongly reduced sedimentation rate between 55 and 38 kyr BP. During these periods of high loess accumulation, sedimentological grain size fluctuations co-vary along numerous west European loess sequences and mimic dust concentration oscillations observed in Greenland ice cores. Other observations chronological coeval with DO (interstadial) events and supporting greater moisture (precipitation) are increased mollusk population (counted individuals), development of tundra gley soils, occurrence of only C3 plants and more negative δ13C. Despite these observations a mechanism linking the sedimentation of the dust at the summit of Greenland and in Western Europe has yet to be proposed and provides the motivation to expand our investigation of loess sequence eastwards in Europe within the 45°N to 48°N latitudinal band. In July of 2009, the well documented Dolni Vestonice brickyard loess sequence (48°53’11.5’’N 16°39’15.8’’E) was resampled over 15 meters for a multi-proxy study, including bulk grain size, micromorphological, mollusk isotope, carbon isotope, luminescence age determinations and rock magnetic analyses. The top of the sequence is capped by a topsoil which appears to be genetically unrelated to the underlying loess. The famous Gravettian archeological layer is intersected at about 6 meters depth and sits on top of massive loess. Between 10 and 14.5 meters depth four paleosols are preserved and overly what is presumably MIS 6 loess. Here we present preliminary result of the magnetic fabric analysis across both loess and paleosol interval and bulk magnetic properties of the Dolni Vestonice loess sequence. Oriented specimens (n = 632) and continuous bulk (n = 306) material where sampled at a frequency for oriented samples of 1 to 4 specimens every 5 cm or 10 cm and continuously for bulk sampling at a 5 cm interval. Both magnetic fabrics and bulk magnetic properties of concentration, mineralogy and grain size show fluctuations co-varying with the sequence’s stratigraphy.