TS3.4 | PICO
Impacts of partial melting on the evolution of the continental crust: different views, one topic
Convener: Alexis Plunder | Co-conveners: Laurent Arbaret, Tanja Knoll, Edward Sawyer
| Thu, 11 Apr, 14:00–15:45
PICO spot 1

In the continental crust, partial melting is now recognized as the main geological process responsible for the production of granites, crustal differentiation of major rheological changes. Many studies (geochemical, petrological, experimental, geodynamical modelling) have shown that partial melting occurring at the grain-scale has consequences at the crustal scale. During its long history heterogeneous continental crust has been through many tectonics cycles with synchronous partial melting and regional deformation. This pairing is critical: melt weakens the rocks allowing faster deformation within mountain building or rifting processes. Dilatant structural sites developed during orogenic deformation accumulate anatectic melt, which begins to crystallize there, before a subsequent shear-enhanced compaction event segregates highly fractionated melt with incredibly evolved compositions to higher crustal levels. These are mainly emplaced as pegmatites, which may be of considerable economic interest. Many interesting questions arise. How does the growth and progressive development of structures affect how melt migrate through the crust, on the grain and macroscales? Does it pump melt though the crust? What is the quantitative effect of partial melting on the effective viscosity of a migmatite? How fast can melt differentiate?
Studying such processes requires a multidisciplinary approach. Therefore we invite contributions to this session from structural analyses, geochemistry, petrology, experimental/rheological studies, field based observations, numerical modeling or geochronology that investigate partial melting at different scales in a heterogeneous and deforming continental crust.