Palaeosols in Saharan and Sahelian dunes of Chad: archives of Holocene North African climate changes

Abstract

Limnic sediments and palaeosols are frequently present in dunes of the Sahara and Sahel deserts of Chad. This study focused on genesis and degree of development of the palaeosols and the timing of soil formation. The soils are Cambic Arenosols formed by precipitation-induced silicate weathering and leaching. The upper parts of the Cambic Arenosols are indurated due to accumulation of salt and amorphous silica during a drier climate following soil formation. The optical age data reveal the occurrence of one or two distinct short-lived humid climate intervals shortly after-5 ka and before-2.5 ka and the formation of local desert lakes shortly after -5 ka. The study further suggests that rapid climate changes occurred mainly in the mid-Holocene whereas the early-Holocene humid period lasted longer.

Keywords

North Africa Holocene humid climate periods palaeosols optical dating Sahara Sahel Chad

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