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@PHDTHESIS{Ptter:820633,
author = {Pötter, Stephan},
othercontributors = {Lehmkuhl, Frank and Markovic, Slobodan B.},
title = {{T}he sedimentary history of loess : sources, deposition,
and reworking of aeolian sediments as indicators for
palaeoenvironmental changes in the {D}anube {B}asin},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2021-05739},
pages = {1 Online-Ressource : Illustrationen},
year = {2021},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2021},
abstract = {Loess is a windblown dust deposit, which covers
approximately $10\%$ of the Earth’s surface. Especially
the Eurasian mid-latitudes are mantled by a belt of loess
deposits spanning from southern England towards the steppes
of Central Asia. Despite its terminal atmospheric
deposition, the formation of loess is a complex chain
including several geomorphological and sedimentological
processes. Aeolian processes cannot solely produce dust
particles in sufficient amounts. During the Pleistocene,
grinding of Alpine glaciers and continental ice sheets –
as well as physical weathering phenomena such as frost
shattering in periglacially influenced high-latitudes and
-altitudes were among the essential formation processes of
silt production. Rivers are another important factor, since
they erode and transport unconsolidated sediments and
increase dust formation due to abrasion during riverine
transport. After the deposition of fluvial and alluvial
de-posits, fine particles, mostly in the silt fraction, can
be deflated and transported by wind. Topographic barriers or
biotic components, such as vegetation or biocrusts, trap the
particles. The aeolian dust undergoes post-depositional
alterations, so-called loessification processes, which help
to preserve the deposit. Despite these processes, loess is
prone to erosion, especially to reworking by water. In
Europe, the distribution of loess and other aeolian
sediments is strongly related to (palaeo-)geographic
conditions and the (palaeo-)climate influencing the process
chain of loess formation. The catchment of the Danube River,
especially in its middle and lower course, is one of the
most important loess regions in Europe since loess covers
vast areas of the basin and the records reach back to the
Early Pleistocene. Due to thicknesses, which in some
instances exceed 50 m, the loess deposits of the Danube
Basin are a crucial archive for palaeoclimatic and
palaeoenvironmental changes in Central and Southeast Europe.
The interplay of the Atlantic, Mediterranean, and
continental climate regimes influences this region. The
present dissertation casts light on the sedimentary history
of loess deposits of the Danube Basin to highlight its
applicability as an archive of palaeoenvironmental changes.
The sedimentary history includes the process chain of loess
formation and possible post-depositional alteration such as
reworking by water. Especially dust deflation, transport,
and deposition via sedimentary pathways, the vegetation
patterns trapping aeolian mineral dust and related ecosystem
qualities, and the post-depositional reworking of aeolian
sediments due to landscape instability are investigated to
understand palaeoclimatic and palaeoenvironmental changes.
This dissertation examines the physical and chemical
properties of seven loess-palaeosol sequences and one
archaeological excavation from various geomorphological
settings to unravel regional environmental patterns for the
Middle and Lower Danube Basin. To reconstruct the deflation
and aeolian transport of dust, sedimentary pathways for
Pleniglacial loess deposits from the Lower Danube Basin are
reconstructed based on geochemical compositions of five
loess-palaeosol sequences, distributed along a cross-section
from the plateau of the Dobrogea in the south towards the
northern Wallachian Plain. The comparison with loess
depos-its of reference regions revealed that the alluvial
deposits of the Danube and its tributaries draining the
Carpathians and Balkan Mountains are the primary source for
the loess deposits of the southern Lower Danube Basin
indicating westerly palaeowind directions. Northwards, a
consider-able amount of dust derived from the rivers
draining the flysch zones of the Eastern Carpathians, such
as Siret, Prut, or Dniester, pointing to stronger
north-westerly winds. Based on stable carbon and nitrogen
isotope analyses of two loess-palaeosol sequences from the
Middle Danube Basin, Irig and Semlac, the vegetation of the
basin during the Middle to Late Pleistocene was dominated by
C3 plants, most likely grasses, which acted as an efficient
dust trap. The isotopic composition of the two sequences
also reveals a palaeoclimatic gradient in the basin, as the
South of the basin seems to have been experiencing drier
conditions compared to the north. The geochemical evidence
highlights the importance of aridity as a palaeoecological
factor that influenced vegetation patterns and ecosystem
qualities during interglacial and interstadial periods. The
Upper Palaeolithic findspot of Temereşti Dealu Vinii was
investigated to reconstruct site-formation processes of a
reworked archaeological open-air site. Temereşti shows no
evident stratification, and lithic artefacts from the
Aurignacian and (Epi-)Gravettian cultural units permeate the
sequence with (typological) age inversions and no horizontal
concentrations. The primarily aeolian sediments were
(sub-)continuously translocated by fluvial processes. Based
on geomorphological evidence and the lack of wear on the
found artefacts, the range of transport is constrained to
the width of the river terrace on which the site is located.
Reworking took place during known phases of landscape
instability during the Holocene in the area. This
dissertation illuminates the steps of the sedimentary
history of loess as palaeoenvironmental indicators for the
Pleistocene in the Danube Basin. It highlights the
importance of multi-proxy approaches by the application of
three different courses on loess deposits from different
milieus. These approaches are combined to unravel regional
palaeoenvironmental patterns of Southeast Europe in the
context of the dispersal of anatomically modern humans into
the subcontinent during the Pleniglacial.},
cin = {551610 / 530000},
ddc = {550},
cid = {$I:(DE-82)551610_20140620$ / $I:(DE-82)530000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2021-05739},
url = {https://publications.rwth-aachen.de/record/820633},
}
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