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- Title
Evidence for an Active, Transcrustal Magma System in the Last 60 ka and Eruptive Degassing Budget (H<sub>2</sub>O, CO<sub>2</sub>, S, F, Cl, Br): The Case of Dominica.
- Authors
d'Augustin, T.; Balcone-Boissard, H.; Boudon, G.; Martel, C.; Deloule, E.; Bürckel, P.
- Abstract
The Morne Trois Pitons-Micotrin volcanic complex on the island of Dominica (Lesser Antilles) emitted a series of plinian eruptions between 18 and 9 ka BP. We studied it to constrain magma storage conditions and volatile degassing balances, by comparison with the three previous ignimbrites (~60-24 ka BP). Volatile concentrations in glass inclusions and mineral-melt thermobarometry indicate storage at ≤200 MPa (~6-8 km) and 860-880°C. The magmas feeding these plinian eruptions were stored at a shallower depth than those that older ignimbrites from the same volcanic complex and stored at ~16 km. Close magma composition and similar halogen ratios, however, suggest a common source for the magmas feeding both the plinian eruptions and the ignimbrites. The large eruptive fluxes of F, Cl, and Br to the atmosphere (up to 1.4-2.8 × 10-1 Mt/km³, 1.5-4.0 Mt/km³, and 2-4 × 10-2 Mt/km³, respectively), estimated by the petrological method, support the potentially important role of volcanic halogens in modifying the chemistry of the atmosphere, though Cl is underestimated here because of buffering in a fluid phase. The behavior of S, potentially partitioned in the same fluid phase, prevents here the calculation of an eruptive outgassing budget.
- Subjects
MORNE Trois Pitons National Park (Dominica); VOLCANIC eruptions; VOLCANOES; IGNIMBRITE; HALOGENS
- Publication
Geochemistry, Geophysics, Geosystems: G3, 2020, Vol 21, Issue 9, p1
- ISSN
1525-2027
- Publication type
Article
- DOI
10.1029/2020GC009050