Environmental evolution and mid–late Holocene climate events in the Valencia lagoon (Mediterranean coast of Spain)

Abstract

Integration of geomorphological, stratigraphic, malacological, sedimentological and micropalaeontological techniques and14C dating allows us to characterise the processes and evolution of the coastal barrier–lagoon system of Valencia (Spain), from the middle Holocene to the historical epoch, as well as the responses to global climate events. Four stages are recognised. Phase 1: around 8240 ± 80 cal. yr BP, a brackish lagoon of moderate energy and in restricted environment was formed, with an energy peak that could correspond to the maximum Holocene marine transgression. Dating (8240 ± 80 cal. yr BP) carried out in peat corresponds to a cold cycle and low water levels in inland lakes of the western Mediterranean. Phase 2: from 6450 cal. yr BP to 3710 ± 130 cal. yr BP, a lagoon remained, in restricted environment and connected with the sea, but with a notable energy decrease and recurrent saturation processes similar to those described in other Mediterranean continental lakes. This phase is contemporaneous with a period of increase in the aridity trend and global cold cycles. Phase 3: from 3710 ± 130 cal. yr BP, a brackish lagoon without marine connection was formed. Towards 820 ± 90 cal. yr BP, a shift to a totally isolated lagoon environment took place (changing from brackish lagoon to freshwater). This process is coeval with a palaeohydrological phase of high flooding frequency in the river flood plains of Spain and Southern France. Phase 4: freshwater lagoon environment becomes a widespread flood plain. During a phase of high frequency and magnitude of floods (‘Little Ice Age’), the flood plain is formed on the top level of the sequence. Phases and processes recorded in sedimentation could be placed in relation with global mid-to-late Holocene events.