燕山式板内造山带基本特征与动力学探讨

CHARACTERISTICS OF YANSHAN TYPE INTRAPLATE OROGENIC BELTS AND A DISCUSSION ON ITS DYNAMICS

板内造山带的基本特征是前期已经固结的岩石圈重新活化。前期地壳基底的复活对后期构造的控制和造山期新生的构造对前期地壳的改造是板内造山作用的两大特征。燕山地区元古宙东西向基底断裂带在中生代的复活控制了区域盖层的构造，表现为沿古断裂的斜滑作用形成的正花状和负花状构造对中生代盖层沉积盆地及其构造的控制，形成盆缘逆冲断层；在基底和盖层中形成羽列式断层及大型ＳＣ 式排列的褶皱和断裂组合。其中的逆冲推覆构造也与发育于板缘的不同，主要为基底卷入型。幔源热活动导致强烈的岩浆活动和地壳被加热、软化，从而诱发变形是造山期新生的特点。燕山的纬向构造被ＮＮＥ向太行山构造带所叠加，以及许多以变质核杂岩和岩浆底辟为代表的垂向构造穿插其中，组成了燕山式板内造山带的主要构造格局。地球内部物质的垂向调整，幔源物质和热流的上升是板内造山带的主因。

The main characteristic of intraplate orogenic belts is its re mobilization of the stable lithosphere consolidated in the earlier stage There are two fundamental features of intraplate orogenic belts, i.e.,the controlling of revival basement to the structures of the cover strata and the reforming of newly formed structures of orogenic stage to the structures formed in the earlier stage The reviving of E-W trending faults in the Yanshan area during the Mesozoic Epoch has controlled the structures of the cover strata The positive and negative flower structures brought about by the transtension and transpression along older faults control the sedimentation and structures of the Mesozoic basins The P typed arrangement of faults and macro S C structures of faults and folds in the cover and basement are also the results of the movement along ancient fault zones The thrusts and nappes in the Yanshan area are different from those in the interplate orogenic belt They are mainly of basement involved type It is considered to be the new feature of the Yanshan intraplate orogenic belt that a Mesozoic active thermal event of mantle origin led to an intensive magma activity and caused the rising of temperature of the crust which was high enough to invoke the softening and deformation of the crust Therefore, the main configuration of the tectonics of the Yanshan orogenic belt is composed of the superimposition of the E-W trending structure belt and NNE trending Taihangshan belt with intercalations of many vertical structures, such as the metamorphic core complexes and igneous diapiric structures The vertical adjustment of the Earth material and the rising of the mantle origin material and thermal activity are the main causes of the intraplate orogeny The gravity and tangential force caused by the Earth's rotation are the main forces resulting the formation of structures of the cover in the orogenic belt and should not be neglected