Trachy-phonolite lava pebbles used in the ancient settlement of Oplontis (Torre Annunziata, Naples): petrochemical data supporting the origin from an old effusive activity of the Somma-Vesuvius volcano

A new study reveals that trachy-phonolite lava pebbles found in the ancient settlements of Oplontis (Torre Annunziata, Naples) and Longola originate from an old effusive activity of the Somma-Vesuvius volcano, predating 8 ka BP. These pebbles, used in building foundations during the Roman period, show petrochemical compatibility with pre-8 ka BP magmas and pyroclastic products, as well as affinity with lava trachyte ejecta from Plinian eruptions preceding the A.D. 79 eruption. Despite their abundance, these pebbles do not match any known lithostratigraphic units, suggesting they were reworked from original lava flows or autoclastic breccias. The research compared samples from Oplontis and Longola to trace their provenance, providing insights into the volcano's complex evolutionary history.

Renzulli, A., Santi, P., Balassone, G., Di Maio, G., De Bonis, A., Di Donato, V., & Morra, V. (2019). Trachy-phonolite lava pebbles used in the ancient settlement of Oplontis (Torre Annunziata, Naples): petrochemical data supporting the origin from an old effusive activity of the Somma-Vesuvius volcano. Annals of Geophysics, 62(1), VO04. https://doi.org/10.4401/ag-7672