Temperature and Pressure Conditions Research of Metamorphism of the Pudeng Formation,Julin Group in the Xujie area of Mouding Country,Yunnan Province
The temperature and pressure conditions are the key factors affecting metamorphism,and also the important basis for discussing the formation environment of metamorphic rocks.In this paper,the plagiohornblende schist from the Pudeng Formation of Julin Group in Mouding,Xujie area of Yunnan Province is selected as the research object,and its petrography,mineral chemical composition analysis and metamorphic temperature and pressure calculation are carried out systematically.The results show that the metamorphic rocks of the Puden Formation in this area have undergone one stage of metamorphism and one stage of hydrothermal fluid alteration.The mineral assemblage of the peak metamorphic stage(Ml)was hornblende+plagioclase+quartz+sphene,which was hot-pressure conditions 589～632℃,0.68～0.80 GPa;while the mineral assemblage in the hydrothermal fluid alteration stage(M2)after the peak is plagioclase(composed of potassium feldspar)+chlorite+sericite,and the formation temperature is 242～311℃.The comprehensive study shows that the western margin of the Yangtze Plate generally experienced a regional metamorphism characterized by middle temperature and low to middle pressure during the Neoproterozoic period,its formation environment is probably related to the continental rift caused by mantle plume activities in the same period.
Pudeng Formation of Julin Groupplagiohornblende schistmetamorphismtemperature and pressure conditionsXujie area
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