RESEARCH

Volcanoes represent the surface expression of larger magmatic systems that supply magmas from depth, sometimes originating deep within the Earth's crust or mantle. Understanding how these systems evolve is essential for a range of applications, including volcanic risk mitigation, the assessment of critical mineral resources, and our broader understanding of global Earth geodynamics.

The recent recognition of crystal mushes as the dominant melt storage medium within magmatic systems challenges our understanding of differentiation processes in various geological settings. A crystal mush can be defined as "any system of crystals and melt (and gases) in which the crystals form a continuous framework through which melt is distributed" (Cashman et al., 2017), and whose "rheology is largely controlled by crystalline framework" (Sparks et al., 2019).

To better constrain the influence of this medium on differentiation processes, I study natural samples, especially the mineral record of magmatic processes, and reproduce key magma differentiation processes by experimental petrology. An overview of past and ongoing research projects is provided below.

EXPERIMENTAL PETROLOGY

Experimental petrology contists in applying the conditions of pressure and temperature at play during magma evolution for a variety of magmatic / metamorphic environments. By using vertical furnaces (1 atm), Internally Heated Pressure Vessels (< 0.5 GPa), and piston cylinders (< 3 GPa), I look into the behavior of mineral and melts focusing on disequilibrium processes.

Disequilibrium partial melting

Status: ongoing (2023 - )

Apparatus: Piston cylinder @ 2 kbar
Natural system analogue: Oceanic magmatic systems, tholeiitic magmas
Principal collaborators: Etienne Médard (LMV), Laurent Arbaret (ISTO), Rémi Champallier (ISTO), Lola Baudry (ISTO)
Host institution: Laboratoire Magmas et Volcans (Clermont-Ferrand, France)
Funding: ClerVolc Postdoctoral Fellowship (UCA)

Equilibrium vs dynamic crystallization

Status: ongoing (2023 - )
Apparatus: Piston cylinder (LMV) & IHPV (ISTO) @ 2 kbar
Natural system analogue: Tholeiitic magmas
Principal collaborators: Etienne Médard (LMV)
Host institution: Laboratoire Magmas et Volcans (Clermont-Ferrand, France)
Funding: ClerVolc Postdoctoral Fellowship (UCA)

Equilibrium and fractional crystallization

Status: past research project (2016 - 2020)

Apparatus: IHPV @ 2 kbar
Natural system analogue: Atlantis Bank (SWIR), oceanic magmatic systems
Principal collaborator: Chao Zhang (NU Xi'an), Jürgen Koepke (IfE)
Host institution: Institut für Erdsystemwissenschaften (IfE Hanover, Germany)
Funding: MESR doctoral grant (UL), DAAD (Deutscher Akademischer Austauschdienst)
Publication:

Boulanger, M., Zhang C., France, L., Toussaint, A., Koepke J. (under revision - Contributions to Mineralogy and Petrology). Equilibrium and fractional crystallization of a tholeiitic magma at 0.2 GPa and implications for magmatic accretion at slow-spreading ridges.

NATURAL SAMPLES

Igneous rocks contain evidence of processes through which they form. Interpreting this evidence can be harduous due to the complexity of this record (melt & minerals), but also due to our current understanding of the magmatic processes themselves. I combine detailed petrographic description and high-resolution (in situ) geochemitry to help resolve magma differentiation processes and their potential consequences.

Magmatic accretion at fast-spreading ridges

Status: ongoing (2024 - )
Study area: Site GT1 and GT2, Oman Drilling Project (Semail ophiolite, Oman)
Principal collaborators: Lisa Cadoux (MSc, CRPG), Lydéric France (CRPG), Satish Singh (IPGP)
Funding: IODP France 2017 (M. Boulanger & L. France - CRPG), ANR Mush Ocean 2023 (M. Boulanger - LMV), ERC Advanced Grants 2023 MohoLab (PI S. Singh - IPGP)

Calc-alkaline crystal mush evolution

Status: past research project (2023 - 2025)
Study area: Adamello batholith (Italian Alps)
Principal collaborators: Alexandre Carrara (PI, former LMV), Catherine Annen (PI, CAS)
Funding: INSU - Mobility Plus & Czech Academy of Science

Magmatic accretion at slow-spreading ridges

Atlantis Massif & Kane Megamullion (Mid-Atlantic Ridge)

Status: past research project (2021 - 2022)
Principal collaborators: Marguerite Godard (GM), Benoit Ildefonse (GM)
Study area: Hole U1309D - IODP Exp. 304/305, Hole 923A - ODP Leg 153
Publication:

Boulanger, M., Godard, M., Ildefonse, B., Bakouche*, M. A comparative study of mineral-melt interactions at Kane Megamullion and Atlantis Massif: Identifying universal processes building the slow-spreading lithosphere. Geochemistry, Geophysics, Geosystems, https://doi.org/10.1029/2023GC011409

Atlantis Bank (Southwest Indian Ridge)

Status: past research project (2016 - 2020)
Principal collaborators: Lydéric France (CRPG), Carlotta Ferrando (UniGe)
Study area: Hole U1473A - IODP Exp. 360, Hole 735B - ODP Leg 118 & 176
Publications:

Boulanger, M., France, L. Cumulate formation and melt extraction from mush-dominated magma reservoirs: the “melt flush” process exemplified at mid-ocean ridges. Journal of Petrology, Perspectives in Petrology https://doi.org/10.1093/petrology/egad005

Dhar, A., Ghosh, B., Bandyopadhyay, D., Morishita, T., Tamura, A., France, L., Nguyen, D.K., Boulanger, M., Koley, M., Roy, S., Chattopadhaya, S. (2022). The lower oceanic crust at ultraslow-spreading Southwest Indian Ridge: The inside story. Gondwana research. https://doi.org/10.1016/j.gr.2022.08.008

Pieterek, B., Ciazela, J., Boulanger, M., Lazarov, M., Wegorzewski, A., Panczyk, M., Strauss, H., Dick, H.J.B., Muszynski, A., Koepke, J., Kuhn, T., Czupyt, Z., France, L. (2022). Sulfide enrichment along igneous layer boundaries in the lower oceanic crust: IODP Hole U1473A, Atlantis Bank, Southwest Indian Ridge. Geochimica et Cosmochimica Acta. https://doi.org/10.1016/j.gca.2022.01.004

Boulanger, M., France, L., Ferrando, C., Ildefonse, B., Ghosh, B., Sanfilippo, A., Liu, C.-Z., Morishita, T., Koepke, J., Bruguier, O. (2021). Magma-mush interactions in the lower oceanic crust: Insights from Atlantis Bank layered series (Southwest Indian Ridge). JGR Solid Earth (Special issue: Ophiolites and Oceanic Lithosphere), https://doi.org/10.1029/2021JB022331

Ferrando, C., France, L., Basch, V., Sanfilippo, A., Tribuzio, R., Boulanger, M. (2021). Grain size variations record segregation of residual melts in slow-spreading oceanic crust (Atlantis Bank; 57°E Southwest Indian Ridge). JGR Solid Earth. https://doi.org/10.1029/2020JB020997

Boulanger, M., France, L., Deans, J., Ferrando, C., Lissenberg, C.J., von der Handt, A. (2020). Magma reservoir formation and evolution at a slow-spreading center (Atlantis Bank, Southwest Indian Ridge). Frontiers in Earth Science (Research Topic: Magma-Rock and Magma-Mush Interactions as Fundamental Processes of Magmatic Differentiation). https://doi.org/10.3389/feart.2020.554598

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