干旱区生态环境知识资源中心

An aeolian dune field migrating to the east encroached on the toes of alluvial fans in the Teruel Basin (eastern Spain) during a short interval in the Late Pliocene (ca 2.9 to 2.6 Ma), when Northern Hemisphere glaciation and strong glacialinterglacial cycles began. Preservation of the dune field was controlled by syn-sedimentary activity of a normal fault. Ephemeral water discharge eroded aeolian sands and formed V-shaped channels in which aeolian sandstone blocks accumulated. The incorporation of loose aeolian sand in wadi waters modified the sediment/water ratio, changing the physical properties of the flows as they penetrated the aeolian dune field. The erosion and cover of aeolian dune foresets by sheetflood deposits suggest that dune-damming caused the intermittent ponding of water behind the dunes and its flashy release. The arid climate in the Late Pliocene western Mediterranean realm favoured the transport of windblown sediments from northern Africa and western Mediterranean land masses into the Mediterranean. The formation of the studied aeolian dune field (2.9 to 2.6 Ma) and possibly others (for example, the Atacama, Namib and Sahara deserts) correlates with a strong increase of the influence of obliquity, which can be attributed to the combination of a regional expression related to the reduced effect of precession due to a minimum in the long-period (2.3 Ma) eccentricity cycle and a remote expression of the onset of the Northern Hemisphere glaciation.