Experimentally Induced Volumetric Re‐equilibration of Plagioclase‐Hosted Melt Inclusions

The application of melt inclusions (MI) to infer magmatic processes assumes the MI have remained as constant mass, volume systems since time trapping. Understanding effects both compositional and volumetric re-equilibration is key for interpretation data. Although behavior in quartz olivine has been studied some detail, process less understood other host phases such plagioclase, a common phase igneous rocks. A can re-equilibrate when it experiences pressure temperature (PT) conditions that differ from formation PT conditions. During laboratory heating, irreversible expansion may occur. As result, internal within decreases, resulting chemical structural changes host. We present results heating experiments on plagioclase-hosted designed induce re-equilibration. consisted incrementally temperatures above homogenization temperatures. At ∼40°C above, at which daughter minerals melted, lowered MI, led exsolution CO2 into vapor bubbles. With each additional few degrees episodes exsolution, bubble nucleation bubbles occurred. Re-equilibration plagioclase occurred through combination ductile brittle deformation surrounding whereas previous studies shown dominantly associated with movement along dislocations. This consistent differing rheological properties these phases.