High-pressure-high-temperature phase diagram of anorthite

Feldspars are rock-forming minerals that are abundant in various geological environments. Recently we have discovered new high-pressure polymorphs of anorthite (An), albite, microcline at pressures above 10 GPa that feature Al and Si in increased five- and six-fold coordination. Our preliminary ex situ multi anvil experiments have shown that new polymorph An can persist at greater depths than previously thought along colder than average mantle geotherms. Herein we propose to re-visit the HT-HP phase diagram of An to define the stability field of the new polymorph and to investigate its decomposition reactions. The results will be provide mineral physics contain on behaviour of one of the major component of cold and ultra-cold subducting slabs and their seismic activity.