Testing quartz and feldspar luminescence dating to determine earthquake and tsunami recurrence in the area of the giant 1960 Chile earthquake

Coasts on active subduction zones are recurrently affected by great earthquakes and associated tsunamis. Deposits resulting from both tidal inundation after coseismic subsidence and from tsunamis can be radiocarbon dated to infer patterns of earthquake and tsunami recurrence. Yet, finding suitable plant material for radiocarbon dating is not always easy. Luminescence dating provides a more ubiquitously applicable approach, but in such settings remains challenging due to three main reasons: (i) The quartz and feldspar minerals formed on active subduction zones tend to show inadequate luminescence properties; (ii) tsunami deposits may be affected by incomplete resetting of luminescence signals; and (iii) the dosimetry in sequences of tsunami and tidal sand sheets intercalated in marsh soils is often complicated. To evaluate the impact of these factors on luminescence dating accuracy, we re-date previously historically-constrained and radiocarbon dated tsunami and post-earthquake tidal deposits marking some predecessors of the giant 1960 Chile earthquake.