华北晚太古代－早元古代高级变质区的变质PTt轨迹及其地壳热动力学演化模式  

PTt Path and Crustal Thermodynamic Model of Late Archaean Early Proterozoic High grade Metamorphic Terrain in North China

作　　者：金巍[1] 李树勋[1] 

机构地区：[1]长春地质学院地球科学系

出　　处：《岩石学报》1996年第2期208-221,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金;地矿部资助

摘　　要：华北高级变质区是早前寒武纪下地壳的组成部分，经历复杂的地质演化。根据变质ＰＴｔ轨迹和变质矿物冷却年龄研究，确定高级变质区ＰＴｔ演化具有两种基本形式：（１）逆时针ＩＢＣ型轨迹和（２）顺时针ＩＴＤ型轨迹。前者属晚太古代末期变质事件，反映在相对稳定环境中地壳的缓慢冷却过程，下地壳冷却速率较小（＜０．３℃／Ｍａ）。后者代表早元古代变质事件，形成于地壳的构造隆升过程，下地壳冷却速率明显加快（２．４～３．７℃／Ｍａ）。高级变质区地壳热动力学状态由晚太古代末期重力均衡条件下的稳定状态转变为早元古代增厚地壳的构造隆升状态。High grade metamorphic terrane in North China is a component of early Precambrian lower crust,which has a complicated evolution history The study of PTt evolution and cooling ages of metamorphic minerals show that the terrane has two patterns of PTt paths, anticlockwise IBC path and clockwise ITD path The IBC path represents later metamorphic event of late Archaean and reflects a slowly cooling process of the crust, with lower cooking rate (<0.3℃/Ma) of the lower crust in relative stable environment The ITD path represents early Proterozoic metamorphic event occuring during structurally uplifting of the crust,the cooling rate of lower crust increased remarkably (2.4～3.7℃/Ma) The thermodynamic state of the crust in high grade metamorphic terrane changed from the stable state under the condition of gravitational equilibrium in the end of late Archaean to the structurally uplifting state of the thickening crust in early Proterozoic The changing resulted from thickening of early Proterozoic continent

关 键 词：华北地区 PTT轨迹 变质岩 热动力学 演化模式 

分 类 号：P588.3[天文地球—岩石学] P541[天文地球—地质学]