 |
| Titel |
Southern African continental climate since the late Pleistocene: Insights
from biomarker analyses of Kalahari salt pan sediments |
| VerfasserIn |
Lukas Belz, Irka Schüller, Achim Wehrmann, Heinz Wilkes |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128109
|
| Publikation (Nr.) |
 EGU/EGU2016-8059.pdf |
|
|
|
|
|
| Zusammenfassung |
| The climate system of sub-tropical southern Africa is mainly controlled by large
scale atmospheric and marine circulation processes and, therefore, very sensitive
to global climate change. This underlines the importance of paleoenvironmental
reconstructions in order to estimate regional implications of current global changes.
However, the majority of studies on southern African paleoclimate are based on
the investigation of marine sedimentary archives and past climate development
especially in continental areas is still poorly understood. This emphasizes the necessity
of continental proxy-data from this area. Proxy datasets from local geoarchives
especially of the southwestern Kalahari region are still scarce. A main problem is the
absence of conventional continental climatic archives, due to the lack of lacustrine
systems.
In this study we are exploring the utility of sediments from western Kalahari salt pans, i.e.
local depressions which are flooded temporarily during rainfall events. An age model based
on 14C dating of total organic carbon (TOC) shows evidence that sedimentation predominates
over erosional processes with respect to pan formation. Besides the analyses of basic
geochemical bulk parameters including TOC, δ13CTOC, total inorganic carbon, δ13CTIC,
δ18OTIC, total nitrogen and δ15N, our paleo-climatic approach focuses on reconstruction of
local vegetation assemblages to identify changes in the ecosystem. This is pursued
using plant biomarkers, particularly leaf wax n-alkanes and n-alcohols and their
stable carbon and hydrogen isotopic signatures. Results show prominent shifts in
n-alkane and n-alkanol distributions and compound specific carbon isotope values,
pointing to changes to a more grass dominated environment during Heinrich Stadial 1
(18.5-14.6 ka BP), while hydrogen isotope values suggest wetter phases during Holocene
and LGM. This high variability indicates the local vulnerability to global change. |
|
|
|
|
|
|