Lava identification by paleomagnetism: a case study and some problems surrounding the 1631 eruption of Mount Vesuvius, Italy

Jaime Urrutia-Fucugauchi,Gennaro Conte-Fasano,Pasquale Tiano,Avto Goguitchaichvili,Alberto Incoronato

doi:10.1186/bf03352611

Jaime Urrutia-Fucugauchi, Gennaro Conte-Fasano + Show 3 more

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https://doi.org/10.1186/bf03352611

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Abstract

Abstract Detailed rock magnetic, paleomagnetic and absolute paleointensity studies of lava flows from the disputed 1631 Mount Vesuvius eruption are reported. The magnetic carrier consists of pseudo-single domain state Ti-poor titanomagnetites. Characteristic magnetization directions determined from detailed stepwise alternating field and thermal demagnetizations provide four new well-defined flow unit mean directions, with α95 ranging from 0.7° to 2.6°. Paleodirections for 11 lava flows from 24-four flows studied previously appear to be related to the 1631 eruption, as indicated by their correlation to the early 17th century segment of the Italian paleosecular variation reference curve. This provides new evidence supporting the conclusion that the 1631 episode was an explosive-effusive eruption. The paleointensity results obtained from this study are the first to be published for Mount Vesuvius, with virtual dipole moments of 9.24±1.8 × 1022 and 13.5±0.4 × 1022 Am2 higher than the present-day geomagnetic field strength.

Highlights

The Somma-Vesuvius complex is localized in the Campania plain, a region of southern Italy bordered by Mesozoic carbonate platforms
The Somma-Vesuvius complex is formed by two superposed volcanic structures: Vesuvius volcano, with a conical shape truncated at the summit, and the older Somma volcano, which represents the caldera of the volcanic complex
We re-examined previously published paleomagnetic data and assessed these data in combination with new, high-quality rock magnetic, paleomagnetic, and absolute paleointensity results that we obtained from lava flows that are presumed to be associated with the 1631 eruption

Summary

Introduction

The Somma-Vesuvius complex is localized in the Campania plain, a region of southern Italy bordered by Mesozoic carbonate platforms. We re-examined previously published paleomagnetic data and assessed these data in combination with new, high-quality rock magnetic, paleomagnetic, and absolute paleointensity results that we obtained from lava flows that are presumed to be associated with the 1631 eruption. Thirty-four samples were pre-selected for the Thellier paleointensity experiment on the basis of stable, onecomponent magnetization accompanied with relatively high median destructive field (MDF) values, elevated blocking temperature, and reasonably reversible k-T curves.

Results

Conclusion