论燕山地区燕山运动

本文在研究了燕山地区中生代区域火山─沉积建造、火山喷发活动及岩浆侵入规律以及构造特征的基础上，认为中生代燕山运动启始于晚三迭世（１９０Ｍａ），终止于早白垩世末（１１０Ｍａ）。其演化历史可以分为三个阶段：即三个构造幕：第一幕发生在晚三迭世末至早中侏罗世，时限约为１９０～１６０Ｍａ；第二幕出现在中侏罗世早期至晚侏罗世末（１６０～１２０Ｍａ）；第三幕从早由垩世开始，早白垩纪末期结束（１２０～１１０）Ｍａ。各幕的发展即有一定规律也有不同的特点。

The Mesozoie Yanshanian Movement in the Yanshan Mountain Range,Norht China

Geological details of the Yanshan Movement are best exposed in the Yanshan Mountain Range. This is well known for it's continuous Mesozoic stratigraphy, intensive plutonism and complicated tectonic history. The type area has interested geologists and scholars in both China and abroad for many years.After studying the regional volcano-sedimentary formations, volcanism and the structural feature of the Yanshan Mountain Range area, the author has coneluded that the Mesozoic Yanshanian Movement took place during the late Triassic Period (-190Ma) and culminated towards the end of the Cretaceous Period (-110Ma). The evoluion of the area can be divided into three main phases of development: Phase 1: Extensional phase occurs from late Triassic to the beginning of the middle Jurassic Period (190-160Ma). Phase 2: Major compressional phase ranges from Middle Jurassic to Late Jurassic (160-120Ma ).Phase 3: Weak compressional phase completes the tectonic movememt in the EarlyCretaceous period (120-110Ma) The main charaeteristics of the Yanshanian Movement are as follows: An initial phase of extension at a regional scale is followed by a regional compressional event. A sedimentary basin with faulted margins was developed during the extensional event. Lacustrine and fluviatile sediments were deposited and interlayered with baste to intermediate volcanic rocks within the lake sediments which was followed by a period of interlayering of aeid extrusives and red bed fluvial sediments. Thrust faulting associacted with secomdary folding occurred along the margins of the basin aftersedimentation was halted by compressional deformation.The Yanshanian Movement can also be characterized by the display of three phases of basin deveopment during the extensional tectonic regime and three stages of thrusting which is associated with the main folding and compressional tectonic event. The overall orientation of the basin and subsequent fold belt is shown to be NEE-NE-NNE.