辽西建平地区区域构造演化与地球动力学探讨

REGIONAL TECTONIC EVOLUTION AND GEODYNAMICS IN JIANPING AREA,WESTERN LIAONING PROVINCE

根据辽西建平地区沉积建造、变质作用、岩浆活动和构造变形等方面的特征,将区内的构造演化大体划分为4个阶段:克拉通基底形成阶段(新太古代—古元古代末)、克拉通盖层发育阶段(中元古代开始直至古生代末期)、板内造山阶段(晚古生代末—中生代)和新构造运动发展阶段(古近纪以来).吕梁运动、印支运动和喜马拉雅运动是4个演化阶段的转折点,燕山运动则奠定了该区现今的构造轮廓.板内造山阶段分为始板内造山阶段(晚二叠世末—中侏罗世)和主板内造山阶段(晚侏罗世—晚白垩世).地球动力学特征显示始板内造山期的造山机制为受兴蒙造山带超碰撞期远程影响的陆内俯冲作用,而主板内造山期的造山机制则属于受太平洋板块俯冲远程影响的大陆边缘型造山作用.

Based on the sediment formation,metamorphism,magmatic activity and structural deformation,the tectonic evolution in Jianping area of the Western Liaoning Province is divided into four stages,i.e.1） the formation stage of craton basement（Neoarchean to the end of Paleoproterozoic）;2） the development stage of craton cover（from the beginning of Mesoproterozoic to the end of Paleozoic）;3） the orogenic stage of intra-plate（end of Late Paleozoic to Mesozoic） and 4） the development of neotectonism（since Paleogene）.The Lvliang Movement,Indosinian movement and Himalayan movement are the turning point of these evolution stages,while the Yanshanian movement eventually forms the present tectonic outline.The orogenic stage of intraplate can be subdivided into initial stage（end of Late Permian to Middle Jurassic） and the main stage（Late Jurassic to Late Cretaceous）.The geodynamic characteristics indicate that the orogenic mechanism of the initial orogenic stage of intraplate is the intracontinental subduction resulted from the collision of Xing-Meng orogenic belt.The orogenic mechanism of the main stage is the continental marginal orogeny,which is obviously caused by the subduction of Pacific plate.