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Cyclicity patterns of Quaternary vega sequences on the eastern Canary Islands

By our DFG funded project “On sedimentation pattern of the eastern Canary Islands”, we are concentrating on two sediment archives, the dune sequences on Fuerteventura and the Vega sequences on Lanzarote. So called “Vegas” are dammed valleys which act as sediment trap since the damming. The vega sediments consist of redeposited (soil-)sediments from the slopes, volcanic material and dust deposits originating from the northern African continent. In those vegas well differentiated sediment layers can be recognised with alternating pale calcified layers (pcl) and reddish clay dominated layers (rcl). This alternation shows a recurring pattern within the profile. So far we interprete such a sequence of one pcl and one rcl as follows:

A massive deposition of silt dominated dust is followed by a period of de- and recalcification. At the same time, soil formation takes place on slope positions within the catchment due to more humid conditions. With the onset of aridisation, clay dominated material (> 80% clay) from the slopes is transported to the valley floor with a simultaneous increase in dust accumulation. The aridisation culminates in a next massive aggradation of silt dominated dust.

The transition from a pcl to a rcl above is characterised by a quartz and Zr minimum. Within the rcl layer the quartz and Zr contents increase continuously (due to increasing dust input) and reach its peak during the next massive dust event. Whereby massive dust events seem to be linked to terminations of African Humid Periods.

Details

Author
Christopher-B. Roettig1, Jakob Labahn1, Thomas Kolb2, Christina Günter3, Anja Schleicher4, Carsten Marburg1, Paul Kanig1, Dominik Faust1
Institutionen
1TU Dresden, Germany; 2Justus-Liebig-University Gießen; 3University Potsdam; 4GFZ Potsdam
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/9css-x854
Geolocation
Canary Islands