Simulation of low-calcium pyroxenes crystallization in basite systems

New parameters of equations of low-calcium pyroxenes - melt geothermometers have been obtained using new experimental data. The new Opx - melt geothermometer allows one to calculate Wo contents in solid more precisely than the old ones, This feature is important to calculate some dynamic parameters of intrusion formation by means of reverse modelling. The proposed Opx geothermometer has average error of orthopyroxene crystallization temperature of about 8 degrees C, it reproduces compositions with En, Fs, Wo better than 1-2 mol.% with 92% chance of occurring. The new Pig - melt geothermometer allows one to calculate pigeonite liquidus temperatures with average precision approximate to 5 degrees C, compositions - better than 1.5 mol.% with 88, 92, and 85% chance of occurring for En, Fs, Wo respectively. It has been stated that too low calculated pigeonite crystallization temperatures as compared with the experimental ones were clue to insufficient precision of the geothermometers Ol-, Pl-, and Aug- melt within the area of crystallization of ternary and quaternary cotectics where pigeonite appeares in the natural magmas. The developed geothermometers can be applied for computer simulation of crystallization of Earth's basite magmas.