Chemical fingerprints of large felsic eruptions in the last 300 kyrs from Tenerife, Canary Islands

Tenerife (Canary Islands) has experienced numerous explosive felsic eruptions over the last 300 kyrs. The stratigraphy and timing of these events within the most recent cycle of phonolitic volcanism, the Diego Hernandez Formation (ca. 600 – 170 ka), is constrained proximally, with petrological studies (whole-rock and isotopes) revealing the generation and storage of melts below the caldera complex. It is likely that several of these events dispersed distally across the North West African margin. However, despite the number of large-magnitude eruptions over the last 300 kyrs, there are limited glass chemical data for these eruption deposits. The lack of glass chemical datasets means distal fallout from these events cannot be robustly correlated to a particular eruption, limiting their use as chronological markers in terrestrial or marine records.

Here we present the major and trace element compositions of volcanic glass shards from major eruption units in the last 300 kyrs, including the deposits of large (VEI ≥ 6) caldera-forming eruptions, such as El Abrigo at ca. 170 ka. The major element compositions are heterogenous, which is consistent with eruptions tapping multiple melt bodies at various stages of magmatic evolution, and there is little variation between successive eruptions. Nonetheless, the trace elements are relatively unique and thus provide distinctive chemical fingerprints for each eruption. These trace element compositions have facilitated the correlation of some of these eruptions to offshore marine records, providing further occurrences that can be used to refine dispersal and magnitude estimates. Furthermore, since at least some of these eruption deposits are well dated, the associated tephra layers can be used as chronological markers in sedimentary sequences in which the tephra are preserved.