Soil moisture fluctuations recorded in Saharan dust deposits on Lanzarote (Canary Islands) over the last 180 ka

Abstract

Aeolian sediments trapped in volcanically dammed valleys on Lanzarote, Canary Islands, were investigated in order to reveal environmental changes over the last 180 ka. Clay content and frequency dependent magnetic susceptibility were used as proxies for pedogenesis and palaeo-soil moisture. During the last 180 ka, these proxies showed a general pattern of enhanced soil moisture during glacials and stadials and more arid conditions during interglacials and interstadials. Comparisons of these results with proxies from regional palaeoclimate studies identified a positive correlation with proxies of trade wind strength off northwest Africa and inverse correlations with both sea surface temperatures in the northeast Atlantic and the extent of Mediterranean vegetation. Possible causes for the observed pattern include a glacial enhancement of precipitation from westerly cyclones, a change in relative humidity due to fluctuating air temperatures and an occasional influence of the African summer monsoon. Although it is not yet possible to clearly differentiate among these factors, it is clear that the first two factors must have been primarily dominant. These results represent the first quasicontinuous terrestrial data testifying to environmental changes in the northwest African coastal area for the last 180 ka and complement the abundant data derived from marine cores of the region. High latitude dynamics had a major influence in this area and were intermediated by North Atlantic sea surface temperatures. A possible negative correlation can also be observed with the orbital obliquity cycle with a 10 ka time lag, which is similar to the lag recorded from North Atlantic sea surface temperatures.

A contribution to the understanding of late Pleistocene dune sand-paleosol-sequences in Fuerteventura (Canary Islands)

“…Discrimination This suggests that soil formation, dune sand accumulation and intensive erosion processes took place during glacial times, in agreement with Suchodoletz et al (2010). However, age underestimates cannot be ruled out, as explained above.…”

“…The intensity degree of soil formation processes can be linked to the duration of the soil formation phase. From our previous studies on Lanzarote Island (Suchodoletz et al, 2010(Suchodoletz et al, , 2009 …”

New perspectives on coastal landscape reconstruction during the Late Quaternary: A test case from central Israel

“…Atlantic westerlies and monsoon circulation are responsible for advecting precipitation in the Mediterranean area in winter. These include the Atlantic shores of south-western Spain (i.e., Huelva and the Gulf of Cadiz; Zazo et al, 2005Zazo et al, , 2008) and the Canary Islands (i.e., Lanzarote; von Suchodoletz et al, 2010).…”

“…These wetter climatic conditions, coaeval with Sapropel S2, also enhanced pedogenesis across the Canary Islands, which were influenced by fluctuations in the Saharan dust supply, and are reflected in changes in environmental conditions in the northwest African region (Bozzano et al, 2002). For example, a clay-rich, brown-red palaeosol with high MS values was formed throughout Lanzarote, dated from 55 to 30 ka (von Suchodoletz et al, 2010).…”

“…A depositional gap of aeolian sediments during lower sea level phases has been described for other Mediterranean coastal areas, and even beyond it. These included Egypt (El-Asmar, 1994;El-Asmar and Wood, 2000), Tunisia (Mauz et al, 2009;Elmejdoub et al, 2011) southern Spain (Zazo et al, 2008) and the Canary Islands (von Suchodoletz, et al, 2010), occurring from 70 ka in the Mediterranean and from 30 ka in the Canary Islands to Mid-Holocene. The longer hiatuses in sedimentation documented in the northern coasts of Egypt (shelf-break curvature 0.15°) and northern Tunisia (0.1°) are presumed to be the result of the shallower coastal profile, compared to Israel's shelf bathymetry (0.5°) (Almagor et al, 2000;Sade et al, 2006;Amante and Eakins, 2009).…”