Partial melting of rocks and subduction zone

Excerpt from the syllabus:
Grade 12: Magmatism in subduction zones: a production of new continental materials (1-B-3)

Procedure:
The activity allows for an analogical modeling of the partial melting of a solid whose composition is controlled.
The objective is to demonstrate that this partial melting produces a liquid phase whose composition differs from the original rock (and therefore from the remaining solid phase) in the case where this solid has a heterogeneous composition.
Placement in the curriculum: the proposed approach comes after studying the magmatic rocks of subduction zones on one hand, and demonstrating that the peridotite of the mantle of the overriding plate is the source rock of magma in these zones on the other hand.