Developing a tephrostratigraphic framework for the Azores and Canary Islands to correlate and date archaeological and palaeoenvironmental records in NW Africa

Archaeological sites in NW Africa spanning the last ~300 kyrs are rich in human fossils and artefacts and have emerged at the forefront of evolutionary studies. However, these records lack a precise chronology, preventing robust assessments of the drivers of cultural and behavioural transitions. Investigations reveal that numerous volcanic ash (tephra) layers are interbedded within the Palaeolithic cave sequences and these likely originated from large volcanic eruptions in the Azores and Canary Islands. These tephra layers are also preserved in offshore marine records that have palaeoclimate data, and these can be used as time-stratigraphic markers to correlate the sedimentary proxy records in this region.

The explosive eruption histories of the Azores and Canary Islands have been studied, but prior to our investigations, there were limited glass chemistry data for the large explosive eruptions over the last 300 kyrs. Here we present and discuss the major and trace element glass compositions of the deposits from the Azores and Canary Islands. These data provide insights into melt storage and eruption at these ocean island volcanoes. Furthermore, we use these glass chemistry data to correlate the proximal eruption deposits with distal tephra identified in marine records and cave sites. This integrated tephrostratigraphy allows us to refine the timing and dispersal of major felsic eruptions and to precisely link volcanism, climate, and Palaeolithic cultural records, thus permitting their interrelationships to be interrogated.