Abstract
ABSTRACTThe mineral magnetic properties of Pleistocene aeolian dune sands from the island of Fuerteventura (Canary Islands, Spain) were studied in order to reconstruct the palaeoenvironmental evolution of Pleistocene climates during their formation. The palaeodunes on Fuerteventura mainly consist of carbonate sands admixed with dust and material of volcanic origin. Due to the low magnetic background caused by the diamagnetic character of carbonate sands, these archives offer a lot of potential for environmental magnetic studies to detect the imprint of dust, volcanic material and paedogenesis. Four sections of alternating palaeosurface–aeolianite sequences in palaeodune fields have been analysed by means of extensive rock magnetic measurements. These Quaternary archives consist of deposits originating from different sources. I. material blown from the shallow shelf, II. material of volcanic origin, and III. long‐range transported dust. The rock magnetic findings enable a more detailed interpretation of the palaeosurfaces within the sequences. We are able to differentiate semiquantitatively between the different source materials on one hand and to distinguish on the other hand those from soil‐forming processes. Soil formation is only weakly developed in the dust imprints in the palaeosol aeolianite sequences, linked to sparse vegetation cover during the Pleistocene on Fuerteventura.
Highlights
Carbonate aeolianites are common sediments and form different coastal landscapes all over the world (Brooke, 2001)
Larrasoaña et al (2015) described magnetic values for dust imprint from the northeastern Sahara in marine sediments in the Mediterranean. Those results are comparable with our investigation (e.g. anhysteretic remanent magnetisation (ARM) mean of 310 × 10−6 Am2 kg−1) confirming a dust imprint accompanied by weak soil‐forming processes
A detailed rock magnetic investigation of the Quaternary aeolianites on northern Fuerteventura yields precise information concerning the magnetic behaviour of this complex archive
Summary
Carbonate aeolianites are common sediments and form different coastal landscapes all over the world (Brooke, 2001). On Fuerteventura (Canary Islands, Spain), the imprint of Saharan dust and of material originating from different periods of volcanic activity complete the complex formation of mainly calcareous palaeodune fields (Roettig et al, 2017). Those materials shape the palaeosurfaces which were established during periods of little or no sand accumulation. Dust accumulation is assumed to be the dominant factor, whereas soil‐forming processes are expected to be of minor intensity (Roettig et al, 2019) These archives of alternating aeolianite–palaeosurface sequences offer the possibility to get a detailed understanding of the palaeoenvironmental conditions of the island. As pure carbonate sands bear a very low magnetic background signal, environmental magnetic methods are powerful at recognising any kind of extraneous input and secondary imprint as paedogenesis reflecting palaeohumidity fluctuations
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