Publications des scientifiques de l'IRD

Samaniego Pablo, Rivera M., Manrique N., Schiavi F., Nauret F., Liorzou C., Ancellin M. A. (2020). Linking magmatic processes and magma chemistry during the post-glacial to recent explosive eruptions of Ubinas volcano (southern Peru). Journal of Volcanology and Geothermal Research, 407, 107095 [25 p.]. ISSN 0377-0273.

Titre du document
Linking magmatic processes and magma chemistry during the post-glacial to recent explosive eruptions of Ubinas volcano (southern Peru)
Année de publication
2020
Type de document
Article référencé dans le Web of Science WOS:000598061400010
Auteurs
Samaniego Pablo, Rivera M., Manrique N., Schiavi F., Nauret F., Liorzou C., Ancellin M. A.
Source
Journal of Volcanology and Geothermal Research, 2020, 407, 107095 [25 p.] ISSN 0377-0273
Understanding the links between the magma differentiation processes, the magma plumbing system and the magma composition at arc volcanoes is of paramount importance for volcanic hazard assessment. In this work we focus on the post-glacial, Holocene, historical, and recent eruption products of Ubinas volcano (Peru), which display an overall decrease in silica content from the older, plinian (VEI 3-5), rhyolitic eruptions (69-71 wt% SiO2) to the historical and recent (2006-2009, 2013-2017), vulcanian (VEI 1-2) basaltic andesitic eruptions (55-57 wt% SiO2). Based on a comprehensive study of the major and trace elements and the Sr-NdPb isotopes, we conclude that this temporal pattern reflects the evolution of the Ubinas magmas in the middle-to-upper crust by a coupled Assimilation-Fractional Crystallization (AFC) process involving a cumulate composed of plagioclase, amphibole, clinopyroxene, orthopyroxene and Fe-Ti oxides, with minor amounts of olivine and biotite at the mafic and felsic end-members, respectively. Upper crustal assimilation is limited to 5-8 vol%, but the overall radiogenic Sr-Nd-Pb signature of the Ubinas magmas requires a larger crustal component, which must therefore occur at middle to lower crustal depths. The petrology of the Ubinas magmas also points to an overall increase in P-T conditions: the large Holocene dacitic and rhyolitic eruptions record temperatures ranging from 800 to 850 degrees C and pressures in the range of 200-400 MPa, whereas the historical and recent (2006-2009, 2013-2017) basaltic andesitic eruptions provide higher temperatures and pressures (1000 degrees C, >300-400 MPa). Overall, the thermo-barometry, phase equilibrium and geochemical constraints allow us to pro pose the existence of a middle-to-upper crust magma column composed of a highly crystalline magma mush containing batches of liquid magma, which seems to be continually recharged from deeper levels. On the basis of the petrological nature of the historical basaltic andesitic eruptions (1667 CE, 2006-2009, 2013-2017), we postulate that during the last centuries, Ubinas experienced a recharge-dominated process, with no evidence for a rejuvenation of the silica-rich reservoir that fed the large Holocene dacitic to rhyolitic eruptions. This study highlights the importance of detailed petrological studies of Holocene sequences at explosive arc volcanoes in order to constrain the magmatic processes and conditions that control large explosive eruptions.
Plan de classement
Géophysique interne [066]
Description Géographique
PEROU
Localisation
Fonds IRD [F B010080547]
Identifiant IRD
fdi:010080547
Contact