TY - JOUR
TI - Thermodynamic research of jadeite jade at high temperatures and high pressures based on phase balance intelligent calculation
AU - Ying Guo
AU - Weixi Tang
AU - Yonghong Xiang
AU - Ming Qi
AU - Jingxiao Bi
JN - Thermal Science
PY - 2019
VL - 23
IS - 5
SP - 2659
EP - 2665
PT - Article
AB - Based on the thermodynamic calculation of chemical composition and the intelligent calculation of phase equilibria, the temperature-pressure of the diagenetic environment of Burma jadeite-jade was studied, and its metamorphism was ver¬ified. Firstly, the Wkj value and activity of the four end-member of jadeite (Jd), augite (Acm), diopsite (Di), and hedenbergite (Hed) were calculated. Jadeite rock system was simplified as NCFMASH, and the equilibrium temperature-pressure conditions of both the combination of quartz and jadeite, sodium-feldspar with little kyanite, and the combination of jadeite diopside, hedenbergite, kyanite, sodium-tremolite, tremolite and oblique zoisite were revealed as 751°C with 17.0 kb, and 631°C with 18.8 kb. Based on the two kinds of mineral combination with a small amount of sodium mica [Pa], the balance of the system temperature should be in the range from 700-770°C, and balanced pressure-range should be in the range from 17.34-18.83 kb, which reflects the pure NCFMASH system hard rock type jadeite-jade rock formation of the real balance temperature-pressure range. It is concluded that the metamorphism of jadeite rock has a stable growth equilibrium temperature-pressure range, which is the reaction interval of the closed system NCTNASH. It is explained that the reason that synthetic jadeite-jade reaches the gem level is that it has not been simulated as a mineral assemblage in the later stage and it will be subjected to multi-phase dynamic metamorphism after the rock forms, so it is unreasonable that jadeite synthesize is not just from one mineral crystals.