Paleoflood records from sinkholes using an example from the Ebro River floodplain, northeastern Spain

53 Pags.- 10 Figs. The definitive version is available at: https://www.cambridge.org/core/journals/quaternary-researchThis work introduces for the first time the concept of using sinkholes in fluvial valleys as recorders of past floods. The notion is illustrated through the investigation of a complex sinkhole located in a broad floodplain underlain by salt-bearing Cenozoic evaporites. This active sinkhole comprises a large subsidence depression affecting the floodplain and the edge of a terrace, and a nested collapse sinkhole that used to host a sinkhole pond. A borehole drilled in the buried sinkhole pond revealed an ~7.8-m-thick fill that records around 2700 yr of clayey lacustrine deposition interrupted by three types of detrital facies. Two thick pebble gravel beds have been attributed to major high-competence floods: a paleoflood that occurred in Visigothic times (1537–1311 cal yr BP) and the 1961 Great Ebro River Flood, which is the largest event of the instrumental record. A trench dug in the portion of the terrace affected by subsidence exposed a mid-Holocene slack-water paleoflood deposit. The disadvantages and advantages of sinkholes as archives of past flood histories are discussed.This work has been funded by project CGL2013-40867-P (Ministerio de Economía y Competitividad, Spain). The work conducted by CC has been supported by project PCIN-2014-106.Peer reviewe