燕山地区中生代构造应力场特征

MESOZOIC TECTONIC STRESS FIELD IN THE YANSHAN MOUNTAIN REGION,WEST OF BEIJING

燕山地区现今的构造、地貌景观，是在漫长的地质历史时期，经历了长期、复杂的建造、改造过程而形成的。从沉积建造及构造形变特点来看，自元古宙至古生界，本区构造运动平缓，建造和改造的特点主要反映基底断裂的控制作用。中、新生代构造运动是燕山地区主要造山作用期，基本特征是强烈挤压形成线状褶皱及推覆构造系统。中生代时期，本区构造形变显示水平应力作用的主导性，新生代时期，则以均衡代偿导致的隆升作用为主。本文侧重中生代构造应力场及变形挠度场的重塑，借以恢复本区中、新生代构造形变形成的力学过程及运动程式。

he present landscape of the Yanshan mountainous region was sculptured from rocks that had been formed and deformed during the past long geologic period of time.The region,as characterized by the sedimentary formations and structures had undergone rather weak tectonic movement from middle-late Proterozic to Paleozoic,represented by the dominating role of the basement faults. The major orogeny occurred here in the Mesozoic and Cenozoic,during which the rocks were strongly compressed to form linear folds and nappes.In this paper,emphasis is placed on the reconstruction of the Mesozoic stress field and deflection field of the region so as to restore the mechanics process and the movement leading to the deformation in Mesozoic and Cenozoic times.