M&Ms project - Mantle Melting : Mesurements, Models, Mecanisms

Partial fusion plays an important role in the evolution of the Earth’s composition. It is the cause of most of the chemical differentiation of the mantle and conditions the genesis of the magmas that cause the crust and oceanic plateaus. Unfortunately, many aspects of fusion have so far eluded us, limiting our understanding of the structure of the mantle and its dynamics. The fundamental relationships between geochemical and petrological observations of magmas emitted at the Earth’s surface and the dynamics of the underlying mantle are the substance of this project.

We propose a multidisciplinary approach to mantle fusion that will combine petrology, chemical and multi-isotopic analysis of rock samples, in situ analysis of minor elements in olivines, and analog and digital experiments and modelling. We will study a wide spectrum of basic and ultrabasic rocks, from basalt and lava differentiated from modern ocean volcanoes (Hawaii, Reunion Island, Iceland, Polynesia), through alkaline ultrabasic rocks (meimechites and kimberlites), to the oldest komatiites (3.5 Ga). Our broad approach is nevertheless ambitious and innovative and will allow us to address some fundamental aspects of the evolution of the coat. Among these, we will mention : (a) Determining the proportions of fertile and recycled material in the source of hot spot basalts, which we will use to constrain the long-term fate of the recycled oceanic crust and its survival in the convective mantle and source of plumes. (b) We will establish the fusion temperature on the 3.5 Ga of the best understood Earth’s history in order to improve our understanding of the thermal evolution of the mantle and core and reduce our uncertainties about that of the Earth as a whole.

Our group consists of three partners and includes geochemists, petrologists, geophysicists and physicists modelers. All the analytical and experimental equipment necessary to carry out our project is available in the host institutes. Participants were selected for the complementarity of their expertise and experience in order to address the problem in an optimal way. All are very productive and internationally recognized scientists. They worked either independently or in small groups on topics related to those considered here and published extensively. We are confident that this association will produce important results.

Although our research has potential applications on the subject of metal mines and the environmental impact of major volcanic eruptions, the nature of our project is essentially that of fundamental research. We therefore believe that it is correctly positioned in a "white program" ANR.

– Source, ANR-10-BLAN-0603