Partial melting and reaction along deformation features in plagioclase

Geological processes involving deformation and/or reactions are highly influenced by the rock grain size, especially if diffusion-controlled take place such as metamorphic and diffusion creep. Although many processes, inducing grain-size reduction, documented understood at relatively high stresses low temperatures (e.g., cataclasis) well lower stress higher temperature conditions bulging subgrain rotation), twinning, a plastic mechanism active in various minerals temperatures, has been neglected nucleation site for melting reaction thus cause reduction so far. We conducted experiments on natural plagioclase-bearing aggregates 2.5 to 3 GPa confining pressure of 700°C 950°C using two different apparatus, multianvil apparatus (DDIA) Griggs press, piston-cylinder apparatus. Regardless type, we observe breakdown plagioclase into an eclogite-facies paragenesis, which is associated with partial domain eclogite facies. Partial mostly takes along interphase boundaries. However, several melt patches or decomposition products coincide occurrence twins grain-scale microcracking indicating intracrystalline addition In present study, demonstrate how interplay between brittle twinning can reaction, potential effective size plagioclase-rich rocks impacts their reactivity behaviour.