The Occurrence of Forsterite and Highly Oxidizing Conditions in Basaltic Lavas from Stromboli Volcano, Italy

Cortés, Joaquín A.; Wilson, Marjorie; Condliffe, Eric; Francalanci, L.

doi:10.1093/petrology/egl012

Cited by 51 publications

(38 citation statements)

References 51 publications

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“…Experiments also indicated that olivine modification occurs at T > 1000°C, and is substantially absent in the low temperature range (700–750°C), possibly a kinetic effect due to short run times unable to complete the reaction. Similar textures have been reported also in the literature293233, focused on different products, including Strombolian scoriae, lavas, and angular blocks representing inner portions of the crater zone, and have been interpreted either as processes occurring within the magmatic column (fast change in f O 2 ), or as related to the exposure at high temperature in oxidizing conditions.…”

Section: Recycling Of Juvenile Ashsupporting

confidence: 79%

Identifying recycled ash in basaltic eruptions

D’Oriano

Bertagnini

Cioni³

et al. 2014

Sci Rep

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Deposits of mid-intensity basaltic explosive eruptions are characterized by the coexistence of different types of juvenile clasts, which show a large variability of external properties and texture, reflecting alternatively the effects of primary processes related to magma storage or ascent, or of syn-eruptive modifications occurred during or immediately after their ejection. If fragments fall back within the crater area before being re-ejected during the ensuing activity, they are subject to thermally- and chemically-induced alterations. These ‘recycled' clasts can be considered as cognate lithic for the eruption/explosion they derive. Their exact identification has consequences for a correct interpretation of eruption dynamics, with important implications for hazard assessment. On ash erupted during selected basaltic eruptions (at Stromboli, Etna, Vesuvius, Gaua-Vanuatu), we have identified a set of characteristics that can be associated with the occurrence of intra-crater recycling processes, based also on the comparison with results of reheating experiments performed on primary juvenile material, at variable temperature and under different redox conditions.

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Section: Recycling Of Juvenile Ashsupporting

confidence: 79%

Identifying recycled ash in basaltic eruptions

D’Oriano

Bertagnini

Cioni³

et al. 2014

Sci Rep

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“…In their study of andesitic scorias and andesite -basaltic andesite lavas at Kasayama volcano, Hagi, Yamaguchi Prefecture, Japan, Nagao et al (1996) found extremely Mg -rich olivine (>Fo 98 ) associated with cryptocrystalline precipitates in andesitic scoria, and concluded that Mg -rich olivine and the precipitates were formed by high temperature oxida-tion. Similar correlations between abundance of precipitates and Fo -content of olivine have been found in basaltic lavas from Stromboli volcano, Italy (Cortés et al, 2006) and in basaltic lava flows from a monogenetic volcano in the Big Pine Volcanic Field, California, USA (Blondes et al, 2012).…”

Section: Introductionsupporting

confidence: 70%

Oxidation states of Fe and precipitates within olivine from orthopyroxene-olivine-clinopyroxene andesite lava from Kasayama volcano, Hagi, Yamaguchi, Japan

Ejima

Akasaka

Nagao

et al. 2013

Journal of Mineralogical and Petrological Sciences

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Oxidation states of Fe and precipitates within olivine in orthopyroxene -olivine -clinopyroxene andesite (OpxOl -Cpx andesite) lava from Kasayama volcano, Hagi, Yamaguchi Prefecture, were investigated to reveal the oxidation process of the lava at high temperatures, using electron microprobe analysis, Raman spectroscopy and transmission electron microscopy.Although the Opx -Ol -Cpx andesite lava is generally black in color, in places it has a red -brown surface and reddish -black subsurface. Olivines from the black lava have normal zoning with Fo 68.5−74.9 cores and Fo 64.9−72.9 rims. Olivine in the black lavas with red -brown tint and red -brown lava contains precipitates of Tirich hematite, hematite, magnesioferrite and enstatite, and tends to be Mg -rich (cores: 3+ -ratio, small amounts of Fe 3+ (0.05 atoms per formula unit at maximum) were invariably detected in olivine from the black lava with red -brown tint. Even in olivine in the black lava, Fe 3+ was detected in the rims, although Fe is ferrous in the cores. These facts on the chemical compositions and oxidation state of Fe within olivine phenocrysts and the occurrence of vermicular rod -form titanohematite and magnesioferrite precipitates in olivine provide the evidence for high temperature oxidation, at temperatures above 800 °C.

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“…Higher oxygen fugacity prior the eruption is consistent with the increase of Fe at constant Mg concentrations at the edges of Pl microphenocrysts and phenocrysts and lower Ti/Al ratios in Cpx from Menyailov vent lavas compared to the Naboko vent. Hammer (2006) and Del Moro et al (2013) have suggested that a decrease in Ti/Al in Cpx may signal an fO 2 increase.High-Fo olivines, found in the lavas of the initial stage of the eruption byIzbekov et al (2014), might also be formed as a response to the sharp increase of the oxygen activity from QFM to NNO and even higher during the fissure opening, in manner analogous to that proposed for the origin of lapilli tuff ejecta at Stromboli volcano, reported byCortes et al (2006) and DelMoro et al (2013).…”

supporting

confidence: 55%