云南牟定戌街地区苴林群普登组变质作用温压条件研究
Temperature and Pressure Conditions Research of Metamorphism of the Pudeng Formation,Julin Group in the Xujie area of Mouding Country,Yunnan Province
郭俏萍 1陈友良 2范伟 1付于真 1顾孟娟 1张宝玲 1詹国鑫1
作者信息
- 1. 成都理工大学地球与行星科学学院,成都 610059
- 2. 成都理工大学地球与行星科学学院,成都 610059;地学核技术四川省重点实验室,成都 610059
- 折叠
摘要
温压条件是影响变质作用的关键因素,也是探讨变质岩形成环境的重要依据.笔者选取云南牟定戌街地区苴林群普登组中的斜长角闪片岩为研究对象,对其开展了较为系统的岩相学、矿物化学成分分析、变质温压条件计算,结果表明:该地区普登组的变质岩经历了1个变质作用阶段和1个热液流体蚀变阶段.其中峰期变质阶段(M1)的矿物组合为角闪石+第一期斜长石+石英+榍石,其温压条件为589～632℃、0.68～0.80 GPa;峰期后热液流体蚀变阶段(M2)的矿物组合为第二期斜长石(成分为钾长石)+绿泥石+绢云母,形成温度为242～311℃.综合研究表明,扬子板块西缘在新元古代时期普遍经历了一次以中温、低-中压为特征的区域变质作用,其形成环境很可能与同期地幔柱活动导致的大陆裂谷有关.
Abstract
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.
关键词
苴林群普登组/斜长角闪片岩/变质作用/温压条件/戌街地区Key words
Pudeng Formation of Julin Group/plagiohornblende schist/metamorphism/temperature and pressure conditions/Xujie area引用本文复制引用
出版年
2024
NETL
NSTL
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