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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Concentration variance decay during magma mixing: a volcanic chronometer

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Perugini, Diego [1] ; De Campos, Cristina P. [2, 3] ; Petrelli, Maurizio [1] ; Dingwell, Donald B. [2]
Total Authors: 4
[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
Total Affiliations: 3
Document type: Journal article
Source: SCIENTIFIC REPORTS; v. 5, SEP 21 2015.
Web of Science Citations: 17

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)

FAPESP's process: 09/50493-8 - Crustal and lithospheric mantle models under the Paraná and Chaco-Paraná basins by merging satellite gravity gradiometry, terrestrial gravimetry and geomagnetic and electromagnetic soundings
Grantee:Icaro Vitorello
Support type: Research Projects - Thematic Grants
FAPESP's process: 15/11850-0 - 8th Hutton Symposium on Granites and related rocks
Grantee:Valdecir de Assis Janasi
Support type: Research Grants - Organization of Scientific Meeting