Climatic cycles inferred from the aminostratigraphy and aminochronology of Quaternary dunes and palaeosols from the eastern islands of the Canary Archipelago

• Published in: Journal of quaternary science Vol. 21; no. 3; pp. 287 - 306
• Main Authors: Ortiz, J E, Torres, T, Yanes, Y, Castillo, C, De La Nuez, J, Ibanez, M, Alonso, M R
• Format: Journal Article
• Language: English
• Published: 01-03-2006
• Subjects: Theba; Africa, Sahara Desert; ASE, Atlantic, Canary Is., Lanzarote; USA, Montana; ASE, Atlantic, Canary Is., Fuerteventura
• ISSN: 0267-8179
• DOI: 10.1002/jqs.956

Aminochronological and aminostratigraphical methods have been used to study the Quaternary aeolian deposits from the islands located east of the Canary Archipelago (Fuerteventura and Lanzarote islands and La Graciosa, Montana Clara and Alegranza islets). The extent of racemisation/epimerisation of four amino acids (isoleucine, aspartic acid, phenylalanine and glutamic acid) was measured in land snail shells of the genus Theba. The age calculation algorithms of these amino acids have been determined to permit the numerical dating of these deposits. Eight Aminozones, each defining dune/palaeosol-formation episodes, have been distinguished and dated at 48.6±6.4, 42.5±6.0, 37.8±4.6, 29.4±4.8, 22.4±4.5, 14.9±3.6, 11.0±4.0 and 5.4±1.1kaBP, the first five of them defining cycles of 5-7ka. The alternation of palaeosols and aeolian deposits, which are related to abrupt transitions from humid to arid conditions, are the reflection of globally induced changes in North Africa palaeoenvironmental conditions linked to the effect of African palaeomonsoons on the trade winds and the Saharan Air Layer. Probably these aeolian cycles, with a recurrence period of 5-7ka, are the expression of multiples of the 2.4ka solar-cycle.