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| Titel |
Stratigraphy and paleoenvironments of the early to middle Holocene Chipalamawamba Beds (Malawi Basin, Africa) |
| VerfasserIn |
B. Bocxlaer, W. Salenbien, N. Praet, J. Verniers |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 11 ; Nr. 9, no. 11 (2012-11-14), S.4497-4512 |
| Datensatznummer |
250007392
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| Publikation (Nr.) |
 copernicus.org/bg-9-4497-2012.pdf |
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| Zusammenfassung |
| We describe the Chipalamawamba Beds, early to middle Holocene deposits at
the southern margin of long-lived Lake Malawi. The beds are exposed because
of downcutting of the upper Shire River. The Chipalamawamba sediments are
medium to coarse, yellow to brown sands deposited in lenses varying in
horizontal extent from a few meters to several hundreds of meters. Four
units are recognized; the first three mainly contain lacustrine sediments
deposited during lake high stands about 10.6–9.7 cal ka BP (Unit 1),
7.6–6.5 cal ka BP (Unit 2) and 5.9–5.3 cal ka BP (Unit 3). Sediments of Unit 4 overlay Units 1
to 3, are coarser and display regular foresets and oblique-bedding,
suggesting deposition in riverine environments after installation of the
Shire River (~ 5.5–5.0 ka BP). Freshwater mollusk assemblages and
bioturbation regularly occur in the lacustrine sediments, but are largely
absent from Unit 4. Diverse and often contradicting hypotheses on the lake
levels of Lake Malawi have been proposed for the early and middle Holocene.
The Chipalamawamba Beds allow straightforward recognition of water levels
and provide strong evidence for oscillating lake levels during this period,
rather than continuous high or low levels. Sedimentation rates have been
high and individual shell beds have typically been deposited during a few
decades. Because the Chipalamawamba Beds contain a sequence of mollusk
assemblages with intervals between subsequent shell beds ranging from a
century to a few millennia, they enable paleontological analysis of the
fauna with an unusually high temporal resolution. That some mollusk lineages
inhabiting Lake Malawi are in the early stages of diversification and
radiation increases the paleobiological relevance of these beds. |
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