The edifice of Stromboli volcano gravitationally collapsed several times during its volcanic history (> 100 ka-present). The largest Holocene event occurred during the final stage of the Neostromboli activity (similar to 13-5 ka), and was accompanied by the emplacement of phreatomagmatic and lahar deposits, known as the Secche di Lazzaro succession. A stratigraphic and paleomagnetic study of the Secche di Lazzaro deposits allows the interpretation of the emplacement and the eruptive processes. We identify three main units within the succession that correspond to changing eruption conditions. The lower unit (UA) consists of accretionary lapilli-rich, thinly bedded, parallel- to cross-stratified ash deposits, interpreted to indicate the early stages of the eruption and emplacement of dilute pyroclastic density currents. Upward, the second unit (UB) of the deposit is more massive and the beds thicker, indicating an increase in the sedimentation rate from pyroclastic density currents. The upper unit (UC) caps the succession with thick, immediately post-eruptive lahars, which reworked ash deposited on the volcano's slope. Flow directions obtained by Anisotropy of Magnetic Susceptibility (AMS) analysis of the basal bed of UA at the type locality suggest a provenance of pyroclastic currents from the sea. This is interpreted to be related to the initial base-surges associated with water-magma interaction that occurred immediately after the lateral collapse, which wrapped around the shoulder of the sector collapse scar. Upward in the stratigraphy (upper beds of UA and UB) paleoflow directions change and show a provenance from the summit vent, probably related to the multiple collapses of a vertical, pulsatory eruptive column
We present detailed stratigraphic‐sedimentological and paleomagnetic analyses of Holocene phreatomagmatic deposits at Stromboli volcano (Aeolian Islands, Italy). The investigated deposits belong to the Secche di Lazzaro succession (SDL) and to the Advanced Operations Center of the Department of Civil Defense (COA) succession, both lying on the Neostromboli lavas (ca. 13–5 ka). The two stratigraphic successions have similar stratigraphic position and show a phreatomagmatic origin, likely related to catastrophic magma‐water interaction processes during sector collapse events. However the thermal remanent magnetization data of the lava lithics indicate that deposits of the SDL succession were emplaced at very low temperatures (less than 140°C), whereas the basal part of the COA deposit was emplaced at temperatures between 300–340°C. Paleomagnetic results indicate that the two investigated deposits may be related to two distinct eruptive events occurred during the Holocene. Recent phreatomagmatic activity at Stromboli apparently has occurred more frequently than previously believed. Consequently, we must reconsider the recurrence interval of this dangerous eruptive scenario for Stromboli.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.