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Native sulfur spherules from volcanic water lake and fumaroles (La Soufrière Volcano, Guadeloupe)

Elba Torregrosa-Garma1, Fidel Costa1 , Ivan Vlastelic2, Carole Berthod2

  • Affiliations: 1Institut de Physique du Globe de Paris, Universite Paris Cite, CNRS, France; 2Observatoire Volcanologique et Sismologique de Guadeloupe, Institut de Physique du Globe de Paris, France.

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 86

  • Programme No: 6.8.12

  • Theme 6 > Session 8

Abstract

The level of unrest and state of activity of volcanoes is typically assessed by time series changes of monitoring geophysical and geochemical data. In the case of La Soufrière de Guadeloupe, this includes tracking the composition and temperature of the numerous fumaroles and water from the Tarissan crater lake as the hydrothermal activity is very important at this volcano. Here we report the results of studying the solid particles found in the Tarissan lake and fumaroles as a complementary way to identify changes in the temperature and fluid compositions. We found sulfur spherules of a variety of sizes (typically < 1 mm) that are aggregated and welded in a range of morphologies. Their occurrence indicate temperatures > 113°C in order to have liquid sulfur which agrees with some of the temperatures of the fumaroles but it is higher than that of the water lake (< 110°C). We hypothesize that the spherules collected in fumaroles result from the melting of sulfur crystals previously deposited at lower temperature. This explanation is supported by the recent increase of fumaroles temperature from 95-110°C to 180-210°C. Conversely the origin of Tarissan lake spherules is uncertain. Sulfur spherules have also been reported in other volcanic lakes worldwide (Poas, Costa Rica; Hakone, Japan; among others) and time series changes in presence or absence, their textures, and sizes may be also useful for assessing changes of the hydrothermal and magmatic systems below La Soufrière and thus eventually contribute to identify upcoming eruptions/explosions at this volcano.