摘要
滇西澜沧变质带经历了两期变质变形事件，其时代分别为５１９Ｍａ和２８０～１９０Ｍａ。早期变质变形事件（Ｍ１Ｄ１）可由销长石和石榴石变斑晶的包裹体痕迹确定，形成近Ｅ－Ｗ向的变形构造格局。晚期变质变形作用（Ｍ２Ｄ２）以形成蓝片岩相矿物组合，如以蓝门石（青铝门石）＋多硅白云母＋绿泥石＋石英等为特征，并形成近Ｎ－Ｓ向的变形构造格局．钠质问石以青铝闪石和蓝闪石为主，白云母多为３Ｔ＋２Ｍ；型多硅白云母，其ｂｏ均值在９．０４０Ａ以上；蓝片岩相变质作用的Ｐ、Ｔ条件估计分别为０．６～０．７ＧＰａ和３００℃。晚期变质变形事件经历了二个主要阶段（Ｍ２ａＤ２ａ和Ｍ２ｂＤ２ｂ），分别伴随透入性面理（Ｓ２）和褶劈理（Ｓ３）的形成，蓝门石的４０Ａｒ－３９Ａｒ定年分别为２７９Ｍａ和２１４Ｍａ；Ｍ２ｃＤ２ｃ期局部受到热的扰动，以及出现大量的膝折带或宽缓褶皱。上述变质变形演化历史代表了澜沧变质带的隆升及剥蚀过程。
Lancang metamorphic belt undergone two different metamorphic and deformational events, whose ages are of 519Ma and 280～190Ma, respectively. Early event of metamorphism and deformation(M1D1) is distinguished by studing porphyroblast inclusion trails of garnets and albites,which caused formation of structural framework approximately with E W trend. The later one (M2D2)is characteristic of appearance of high-pressure metamorphic mineral assemblage such as glaucophane, crossite, phengite and stilphnomen, meanwhile generating distinguished structural framework with N-S trend. P,T conditions for metamorphism of blueschist phase are estimated to be 6-7 GPa and 300℃ respectively.The main event of metamorphism and deformation also underwent two different major evolutionary stages (M2D2 and M2bD2b) accomkpaning with forming penetrasive foliations S2 in regional scale and crenulated foliations S3. The ages of these two stages (M2D2 and M2b D2b) are 279 Ma and 214 Ma respectively, the belt during M2cD2c period was locally disturbed by heat and occurred with amounts of kink bands and open folds. The history of deformation and metamorphism as mentioned above represents the processes of uplift and exhumation of Lancang metamorphic belt.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1994年第1期27-40,共14页
Acta Petrologica Sinica
基金
国家目然科学基金
关键词
变质带
变质作用
云南
蓝片岩
Lancang metamorphic belt
Metamorphism
deformation
Porphyroblast
Inclusion trails
