Holocene hydric process in the Lower Guadalentín (Murcia, SE Spain)

Abstract

The lower Guadalentín basin is situated in the South-East of Spain. It is an active graben bounded by the Lorca-Alhama and Librilla faults. Its longitudinal profile is uneven. Rock salients, such as developed at Librilla, have trapped the deposits conveyed by the Algeciras and Librilla torrents (ramblas), which are tributaries of the Guadalentín river. The Holocene sediments contain archaeological artefacts, charcoals, pollen and remains of human settlements that enable us to reconstruct the paleoenvironmental and paleogeographical variations in this area which is characterised by a Mediterranean semi-arid climate. Geomorphic processes remodelled the sediments in two polygenic debris fans during several development stages between 6.500 BP and 2.500 years BP. An alluvial terrace incised in these fan surfaces was developed during the "Little Ice Age" after the eventual aperture of the basin (c.a. 2.500 years BP). The coupling of climatic, neotectonic and anthropic (human), events have been decisive in the Holocen evolution of the studied zone.