Palaeoenvironmental interpretation of Late Pleistocene-Holocene morphosedimentary record in the Valsalada saline wetlands (Central Ebro Basin, NE Spain)

This work presents a palaeoenvironmental interpretation of the Upper Pleistocene-Holocene sedimentary sequence recorded in the Valsalada saline wetland system (Monegros, Central Ebro Basin). This morphosedimentary system developed on karstified, gypsiferous bedrock and was mainly fed by local saline groundwater. Based on geomorphological, sedimentological, palynological and radiocarbon data, three depositional units have been differentiated: 1) a lacustrine unit, which accumulated under cold/cool and humid environmental conditions at 41-40 kyr cal BP, 2) a fluvial unit that was deposited under arid climatic conditions with cold episodic periods from 14 to 3.5 kyr cal BP, and 3) an alluvial slope unit associated with arid climate with human influence during the Late Roman Period (1.5 kyr cal BP). The morphosedimentary evolution of the Valsalada system is strongly influenced by the geomorphic setting (small catchment with karstic depressions and low gradient slopes on gypsum), the hydrological availability (runoff and groundwater discharges) related to climate variability during the Late Pleistocene-Holocene, and the human activities developed in the area during historical times. The response of the Valsalada system displays a low sensitivity to short-term climatic changes but responds to major long-term climatic conditions, improving the regional paleoenvironmental picture of the Late Quaternary in NE Spain.