燕山板内造山带中生代构造演化特征  

Tectonic evolutionary characteristics of Yanshanian intraplate orogenic belt in Mesozoic era

作　　者：郭华[1] 刘红旭[1] 王润红[2] 

机构地区：[1]核工业北京地质研究院,北京100029 [2]中国地质大学,北京100083

出　　处：《铀矿地质》2003年第2期65-72,80,共9页Uranium Geology

摘　　要：燕山地区自晚三叠世以来进入了板内造山带形成演化阶段 ,并具有分期演化的幕式特征。在时间演化序列上 ,可分出造山前期 (T3)、造山主期 (J1～J3)和造山后期 (K1)等 3个阶段。构造变形方面 ,燕山板内造山带的基本构造格局为一大型逆冲推覆系统组成的构造楔形体 ,呈前展式扩展 ,造成的地壳缩短量可达 44 1 %。动力变质作用以高压动力变质为特征 ,发育高压动力变质岩(榴辉岩和高压麻粒岩 ) ,形成于构造应力集中的逆掩断层上盘 ,由中 上地壳长英质岩石转变而成。岩浆岩属钙碱性岩石系列、中酸性岩石组合 ,其中岩石类型、稀土元素配分型式及所反映的构造运动强度均具有一定的特征。在造山带形成过程中伴生 3期同造山磨拉石 :杏石口期磨拉石 (T3x)、后城期磨拉石 (J3h)和青石砬期磨拉石 (K1q) 。Since Late Triassic the Yanshanian region has enter a development stage of intraplate orogeny,which is characterized by multi stage and episotic evolution and may be divided into 3 phases,i.e.the pre orogenic phase (T 3),the main orogenic phase (J 1～J 3),and the post orogenic phase (K 1).With respect to the tectonic deformation,the fundamental tectonic framework represents a huge tectonic wedge composed of a system of overthrust nappes extending in piggyback propogation leading to a crust shortening of about 44 1%.The dynamometamorphism was characterized by high pressure dynamometamorphic rocks (eclogite,high pressure granulite) were formed from the conversion of felsic rocks of middle upper crust at the hanging wall of overthrusts where tectonic stress was concentrated.Magmatic rocks in the region are of calc alkaline series and an intermediate acidic association.Rock types and their REE distribution pattern,as well as the related tectonic intensity are characteristic and typical.The formation of the orogenic belt was associated by three stages of synorogenic molasses,i.e.the Xingshikou molasses (T 3x),the Houcheng molasse (J 3h) and the Qingshila molasses (K 1q) reflecting the episodic evolution and the heterogeneity of tectonic intensity during different orogenies.

关 键 词：中生代 燕山板内造山带 时间演化序列 逆冲推覆构造系统 高压动力变质岩 三叠世 

分 类 号：P542.2[天文地球—构造地质学] P534.5[天文地球—地质学]