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Sources, transport and deposition of terrestrial organic material in southwestern Africa
journal contribution
posted on 2016-10-12, 12:54 authored by Nicole Herrmann, Arnoud Boom, Andrew S. Carr, Brian M. Chase, Robyn Granger, Annette Hahn, Matthias Zabel, Enno SchefussSouthwestern Africa's coastal marine mudbelt, a prominent Holocene sediment package, provides a valuable archive for reconstructing terrestrial palaeoclimates on the adjacent continent. While the origin of terrestrial inorganic material has been intensively studied, the sources of terrigenous organic material deposited in the mudbelt are yet unclear. In this study, plant wax derived n-alkanes and their compound-specific δ13C in soils, flood deposits and suspension loads from regional fluvial systems and marine sediments are analysed to characterize the origin of terrestrial organic material in the southwest African mudbelt. Soils from different biomes in the catchments of the Orange River and small west coast rivers show on average distinct n-alkane distributions and compound-specific δ13C values reflecting biome-specific vegetation types, most notably the winter rainfall associated Fynbos Biome of the southwestern Cape. In the fluvial sediment samples from the Orange River, changes in the n-alkane distributions and compound-specific δ13C compositions reveal an overprint by local vegetation along the river's course. The smaller west coast rivers show distinct signals, reflecting their small catchment areas and particular vegetation communities. Marine surface sediments spanning a transect from the northern mudbelt (29°S) to St. Helena Bay (33°S) reveal subtle, but spatially coherent, changes in n-alkane distributions and compound-specific δ13C, indicating the influence of Orange River sediments in the northern mudbelt, the increasing importance of terrigenous input from the adjacent western coastal biomes in the central mudbelt, and contributions from the Fynbos Biome to the southern mudbelt. These findings indicate the different sources of terrestrial organic material deposited in the mudbelt, and highlight the potential the mudbelt has to preserve evidence of environmental change from the adjacent continent
History
Citation
Quaternary Science Reviews, 2016, 149, pp. 215-229Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Geography/Physical GeographyVersion
- AM (Accepted Manuscript)
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Quaternary Science ReviewsPublisher
Elsevierissn
1873-457X;0277-3791Acceptance date
2016-07-23Copyright date
2016Available date
2018-08-03Publisher DOI
Publisher version
http://www.sciencedirect.com/science/article/pii/S0277379116302633Notes
The file associated with this record is under a 24 month embargo from publication in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.Language
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