| Summary: | Along active margins, large magnitude earthquakes induce submarine slope instabilities, generating turbidite deposits and debris flows. These catastrophic events are recorded in the stratigraphy from the slope basins to the subduction trench. These sedimentary records provide a unique opportunity to time-extend local seismic catalogs, and their analysis is a strong tool to study the age, source and frequency of large past earthquakes. However, one of the main challenges is accurately dating the deposits, especially in settings where few datable foraminifers are available (below the Carbonate Compensation Depths, in low primary productivity environments, within sequences with poorly preserved hemipelagic sediments between erosive turbidites, etc…). In such cases, volcanic ash emitted during the largest eruptions represent robust stratigraphic markers distributed over thousands of square kilometers, which can provide valuable temporal constraints.Marine sediment cores collected during the Amadeus and Atacames oceanographic cruises (R/V L’Atalante; Collot et al., 2005; Michaud et al., 2015) reveal numerous turbidite deposits, which could be a consequence of earthquakes that occurred along the Ecuadorian margin during the Holocene. The knowledge of such events is essential to better assess the present and future seismic hazards, as well as their potentially destructive impact on marine and coastal environments. Silty to sandy turbidite layers are encountered at the mouth of the Esmeraldas and Patia Canyons, in northern Ecuador, whereas fine-grained turbidites are present at the Ecuadorian trench and in slope basins between Punta Galera and the Gulf of Guayaquil. Turbidite sequences are interbedded with volcanic ash and hemipelagic layers. In this study, we provide new 14C ages performed on planktonic foraminifera present in hemipelagic layers to constrain the age of turbidite sequences. We also characterized the lithofacies and geochemistry of distal volcanic ash fallouts, and we propose a first land-sea correlation ...
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