RECONSTRUCTION OF REGIONAL-SCALE FLOW PATHS OF PARTIALLY- MOLTEN CRUST AS RECORDED BY MIGMATITES AND ECLOGITES
In eclogite inclusions in the Montagne Noire migmatite dome, French Massif Central (FMC), mineral and rock composition (bulk, mineral major/trace elements; O isotopes in zircon and garnet; bulk Sm-Nd, Lu-Hf, Rb-Sr), textures (inclusions, symplectites), extent of zircon recrystallization, and deformation fabrics (flattening/constriction at eclogite conditions) allow reconstruction of the flow paths of eclogite and therefore the provenance and flow history of the host migmatite, which no longer records this information. For example, eclogite in the core of the dome is isotopically similar to eclogite and other HP mafic rocks exposed in other FMC domes, whereas eclogite at the dome-margin is distinct. This is consistent with interpretation of zircon textures (highly recrystallized in dome-core eclogite; minimal HP zircon growth in dome-margin) and other observations consistent with the interpretation that dome-core eclogite experienced protracted HT metamorphism and deformation during flow in the deep crust, whereas dome-margin eclogite was more locally-sourced. Variation of paths in different domains of a migmatite complex shows how partially-molten crust flows laterally and vertically on a regional scale and informs early (HP-HT) and later (LP-HT) geotherms during orogenic evolution.