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Basaltic volcanoes

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Volcanoes represent the best expression of magmatic processes at the surface of the Earth. Our research projects make use of detailed textural and geochemical studies of natural rocks as well as laboratory experiments to understand deep differentiation processes beneath volcanoes and their timescales. 
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One of the major scientific question we want to solve is the effect of the crust and particularly the crustal thickness of the properties and compositions of magmas finally erupting at the surface of the Earth on continents and in the oceans.
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We currently work on several regions with active or recently active volcanoes (Snake River Plain, USA; South Volcanic Zones of the Andes, Chile; Virgunga volcanoes, DR Congo; Azores, Portugal) and some regions with record of old volcanic eruptions (Shatsky Rise, Emeishan Province, China).

The South Volcanic Zone of Chile

 

We study a series of volcanoes (Calbuco, Osorno, Villa Rica) in the South Volcanic Zone of Chile. These projects are performed in collaboration with scientists from the University of Liege (Prof. J. Vander Auwera, T. Bechon, P. Fugmann). In these projects we evaluate the role of crystal accumulation on magma compositions and they are controlled by deep mush processes. We also try understanding why some volcanoes seem to be dry whereas others contain abundant hydrous phases. This has an effect not only on phase stability but also on phase compositions. In the next steps of the projects, we will combine natural rocks with laboratory experiments to constrain the timescales of crystal growth and residence times prior to eruption.

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Main investigator: Olivier Namur

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Oceanic basaltic volcanoes

 

We use several examples of oceanic basaltic volcanoes to understand how crystal thickness affects the composition of erupted magmas. We mostly focus on rocks from the thick Shatsky Rise oceanic plateau and on rocks from several islands of the Azores (Terceira, Pico, Sao Miguel). We perform detailed textural and chemical analyses of crystals and glomerocrysts to see how their various zones of crystal growth and resorptions can be linked to different magma storage conditions in the crust. We also combine geospeedometry with accurate measurements of volatiles in melt inclusions to constrain the timescales of magma ascent through the crust. 

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Main investigators: Thomas van Gerve, Kat Shepherd

 

Continental rift volcanoes

 

We perform research on two highly active volcanoes from the Virunga Province, DR Congo: Nyiragongo and Nyamuragira. These volcanoes exert a major threat on the city of Goma. We want to understand why both volcanoes although being only located 15 apart from each other erupt vastly different magma compositions. We also investigate highly primitive samples erupted at both volcanoes to constrain the mantle sources and mantle melting conditions necessary to produce the highly silica-undersaturated lavas observed in Nyiragiongo and the more basaltic compositions observed at Nyamuragira. These studies of natural rocks are combined with laboratory experiments aimed at refining trace element partition coefficients between melt and uncommon magmatic phases.

 

Main investigators: Sander Molendijk, Ephrem Kamathe

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Large igneous provinces

 

Large igneous provinces (LIPs) represent one of the largest expressions of volcanism on Earth, occurring on continents and in the oceans. The actual mechanisms of formation of LIPs are debated mainly because their mantle sources and the thermal structure of the mantle beneath them are not sufficiently constrained. We test the hypothesis that the extreme magma productivity in LIPs is related to a higher than previously thought fraction of recycled material in the mantle which would lower its solidus temperature.  We especially investigate the Emeishan volcanic province in China. We develop new tools to better constrain mantle melting conditions, and especially magma temperature and mantle sources. We also perform experiments to understand the differentiation trends of high-Ti lavas and low-Ti lavas.

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Main investigators Yishen Zhang

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Publications

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  • Namur O., Montalbano S., Bolle O., Vander Auwera J. (2020). Petrology of the April 2015 eruption ofCalbuco volcano, southern Chile. Journal of Petrology.

  • Van Gerve T., Neave D., Almeev R., Holtz F., Namur O. (2020). Zoned crystal records of transcrustal magma transport, storage and differentiation: insights from the Shatsky Rise oceanic plateau. Journal of Petrology

  • Honour V.C., Holness M.B., Charlier B., Piazolo S.C., Namur O., Prosa T.J., Martin I., Helz R., Maclennan J., Jean M.M. (2019). Compositional boundary layers trigger liquid unmixing in a basaltic crystal mush. Nature Communications

  • Vander Auwera J., Namur O., Dutrieux A., Wilkinson C.M., Ganerod M., Coumont V., Bolle O. (2019). Mantle melting and magmatic processes under La Picada stratovolcano (CSVZ, Chile). Journal of Petrology

  • Zhang Y.S., Hou T., Veksler I.V., Lesher C.E., Namur O. (2018). Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province. Lithos 300, 20-32

  • Stechern A., Just T., Holtz F., Banaszak M., Namur O. (2017). Decoding magma plumbing and geochemical evolution beneath Lastarria volcanic complex (northern Chile) - Evidence for multiple magma storage regions. Journal of Volcanology and Geothermal Research 338, 25-45

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