I am currently working on my master thesis, in my working area in south of Brazil occur paleoproterozoic granulites, (Santa Maria Chico Granulitic Complex). And one topic of the my study, is the geothermobarometry these rocks. But my paragenesis with more high grade is: OPX+CPX+Plagioclase+spinel (high Al-spinel) and OPX+CPX+Plagioclase. In both cases I don't have garnet or others high grade minerals, amphiboles are very common but are originated by the retrometamorphism.
These paragenesis, in theory, indicate a high-T and low-P granulitic facies for mafic rocks, but I simulate the samples in thermocalc in TC_comb package, and my high grade paragenises don't have results, in consequence I need put amphiboles, in this case, I have results but the P condicions like 10-18 Kbar with high standard deviation. I would like to know if I have other options or sugestions to calculate geothermobarometry with two pyroxenes+plagioclase+spinel.
Universidade do Vale do Rio dos Sinos (UNISINOS)