Cornelia
Köhler
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Research
of Cornelia Köhler
Hematite
based reconstruction of Saharan aridity and dust flux to the Mediterranean
Ocean during middle to late Miocene tectonic and climatic events
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Project partners:
Bremen: Tilo von
Dobeneck, David Heslop, Ulrich Bleil
Utrecht: Cor Langereis,
Fritz Hilgen, Wout Krijgsman
.
| While the
Miocene biostratigraphy of Central Mediterranean sediments has been studied
in rather detail, the continental influences, in particular, the Saharan
dust records of this period have not been fully investigated. It is therefore
promising to apply the above proposed rock magnetic and voltammetric techniques
for characterizing and quantifying hematite and goethite also to some selected
Miocene time slices, in combination with state-of-the-art environmental
magnetic methods. |
Satellite
image of the Sahara
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Trubi
marls at Punta di Maiata, Sicily
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For an early time
slice at around 13 - 14 Ma encompassing the closure of the Indian Ocean
gateway, suitable marine land sections crop out in Malta (Blue Clay Formation),
at the Tremiti Islands (Cretaccio Formation) and in south-eastern Sicily
(Tellaro Formation). All three sections show lithological cyclicity, partially
overlap and confine an interval of about 3 million years from 13.5 Ma (earliest
Serravallian) to 10.5 Ma (early Tortonian). The astronomical calibration
based on abundance fluctuations of Globigerinoides spp. and CaCO3
content provides an absolute age for several calcareous nannofossil and
planktonic foraminiferal bioevents throughout the interval. |
For a second time
slice at around 7 - 8 Ma enclosing the Tortonian saliniy crisis, the Metochia
section on Gavdos (off Crete), the northern Italian marine Monte dei Corvi
section and the Sicilian Monte Gibliscemi section seem appropriate. While
the organic-rich sapropel layers are probably too intensely overprinted
to yield information on iron oxide mineral content, the more oxic marl
layers will be preferentially investigated. Dated samples from all these
sections are available at our Dutch partners, but some additional field
work may be appropriate at a more advanced stage of this study. |
Publications of Cornelia Köhler
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2008
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Köhler,
C.M., Heslop, D., Dekkers, M.J., Krijgsman, W., van Hinsbergen, D.J.J.
and von Dobeneck, T. (2008). Tracking provenance change during the late
Miocene in the eastern Mediterranean using geochemical and environmental
magnetic proxies, Geochemistry, Geophysics, Geosystems, in press
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