Dating Saharan dust deposits on Lanzarote (Canary Islands) by luminescence dating techniques and their implication for palaeoclimate reconstruction of NW Africa.

Lava flow dammed valleys (Vegas) on Lanzarote (Canary Islands) represent unique sediment traps, filled with autochthonous volcanic material and allochthonous Saharan dust. These sediments and the intercalated palaeosoil sediments document past environmental change of the last glacial-interglacial cycles, both on Lanzarote and in NW Africa. A reliable chronology must be established to use these sediment archives for palaeoclimate reconstructions. Owing to the lack of organic material and the limiLava flow dammed valleys (Vegas) on Lanzarote (Canary Islands) represent unique sediment traps, filled with autochthonous volcanic material and allochthonous Saharan dust. These sediments and the intercalated palaeosoil sediments document past environmental change of the last glacial-interglacial cycles, both on Lanzarote and in NW Africa. A reliable chronology must be established to use these sediment archives for palaeoclimate reconstructions. Owing to the lack of organic material and the limiting time range of the 14Cdating method, luminescence dating is the most promising method for these sediments. However, the fluvio-eolian character of these sediments is a major problem for luminescence dating, because these sediments are prone to insufficient resetting of the parent luminescence signal (bleaching) prior to sedimentation. To check for the best age estimates, we compare the bleaching behavior of (1) different grain sizes (coarse- versus fine-grain quartz OSL) and (2) different minerals (fine-grain feldspar IRSL versus fine-grain quartz OSL). The results show that owing to its bleaching characteristics, quartz is the preferable mineral for luminescence dating. On the basis of the fine- and coarse-grain quartz OSL age estimates, a chronostratigraphy up to 100 ka could be established. Beyond this age limit for OSL quartz, the chronostratigraphy could be extended up to 180 ka by correlating the vega sediments with dated marine sediment archives.show moreshow less

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Metadaten
Institutes:Geowissenschaften
Author: Hans von Suchodoletz, Markus Fuchs, Ludwig Zöller
Creating Corporation:Lehrstuhl für Geomorphologie, Universität Bayreuth
Year of Completion:2008
SWD-Keyword:Kanarische Inseln <Ost>; Lumineszenzdatierung; Quartärgeomorphologie; Sahara; Staub
Tag:ungenügende Bleichung
Holocene; Middle and Late Pleistocene; Saharan dust; insufficient bleaching; luminescence dating
Dewey Decimal Classification:550 Geowissenschaften
URN:urn:nbn:de:bvb:703-opus-3960
Source:Geochemistry, Geophysics, and Geosystems (2008), Vol 9, Number 2,14 February 2008, Q02Q07
Document Type:Working Paper
Language:English
Date of Publication (online):17.03.2008