Concentration variance decay during magma mixing: a volcanic chronometer

Autor(es)

Perugini, Diego ^[1] ; De Campos, Cristina P. ^{[2, 3]} ; Petrelli, Maurizio ^[1] ; Dingwell, Donald B. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Perugia, Dept Phys & Geol, I-06100 Perugia - Italy

^[2] Univ Munich, Dept Earth & Environm Sci, D-80333 Munich - Germany

^[3] Univ Sao Paulo, Dept Mineral & Geotecton, BR-05508080 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: SCIENTIFIC REPORTS; v. 5, SEP 21 2015.
• Citações Web of Science: 16
• Assunto(s): Vulcanismo Vulcões Magma

Resumo

The mixing of magmas is a common phenomenon in explosive eruptions. Concentration variance is a useful metric of this process and its decay (CVD) with time is an inevitable consequence during the progress of magma mixing. In order to calibrate this petrological/volcanological clock we have performed a time-series of high temperature experiments of magma mixing. The results of these experiments demonstrate that compositional variance decays exponentially with time. With this calibration the CVD rate (CVD-R) becomes a new geochronometer for the time lapse from initiation of mixing to eruption. The resultant novel technique is fully independent of the typically unknown advective history of mixing - a notorious uncertainty which plagues the application of many diffusional analyses of magmatic history. Using the calibrated CVD-R technique we have obtained mingling-to-eruption times for three explosive volcanic eruptions from Campi Flegrei (Italy) in the range of tens of minutes. These in turn imply ascent velocities of 5-8 meters per second. We anticipate the routine application of the CVD-R geochronometer to the eruptive products of active volcanoes in future in order to constrain typical ``mixing to eruption{''} time lapses such that monitoring activities can be targeted at relevant timescales and signals during volcanic unrest. (AU)

• Processo FAPESP: 09/50493-8 - Modelos da crosta e litosfera sob as bacias do Paraná e Chaco-Paraná integrando gradiometria gravimétrica por satélite, gravimetria terrestre e sondagens magnéticas e eletromagnéticas
• Beneficiário: Icaro Vitorello
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 15/11850-0 - 8th Hutton Symposium on Granites and Related Rocks
• Beneficiário: Valdecir de Assis Janasi
• Modalidade de apoio: Auxílio Organização - Reunião Científica