鲁东胶北地区的变形与变质演化史

DEFORMATION AND METAMORPHIC EVOLUTION IN THE JIAOBEI REGION,EASTERN SHANDONG

本文依据在烟台－蓬莱－栖霞地区的详细构造与变质研究，分析胶北地区太古代以来的变形与变质演化历史及其意义．继太古代胶东群形成之后的胶东事件，在胶东群中造成了第一期的南北向构造和同构造麻粒岩相高级区域变质．于粉子山群沉积之后、大致１７亿年前发生的粉子山事件使胶北地区基底最后固结．这期造山事件在基底中产生了广泛的平缓变形面理、褶皱及同构造角闪岩相区域变质．晚石炭世的蓬莱事件，以北北东一南南西向挤压造成了蓬莱群及基底中普遍的北西西－南东东向褶皱及低绿片岩相区域变质．蓬莱事件是华北与扬子板块沿胶南带碰撞的结果．胶北地区的后蓬莱事件造成了局部的北北京向膝折和褶皱，并未伴生区域变质．这一变形事件可能是晚三叠世印支运动或侏罗纪燕山运动的结果．

On the basis of detailed studies on structures and metamorphism in YantaiPonglai-Qixia area, deformation and metamorphic evolution of the Jiaobei region since Archaean and their implications are analysed in this paper. The Jiaodong event, which took place after formation of the Archaean Jiaodong Group, caused the first phase of N-S structures and syntectonic granulite facies metamorphism. After deposition of the Fenzishan Group, the Fenzishan event finally solidified the basement in the Jiaobei region 1700 Ma ago. This orogenic event produced large-scale flat deformation foliation, folds and syntectonic amphibolite factes metamorphism in the basement. Under NNE-SSW compression, the late Carboniferous Ponglai event produced wide-spread NWW-SEE folds and low greenschist facies regional metamorphism in the Ponglai Group and basement. The Ponglai event occurred as a consequence of collision between the North China and Yangtze Plates along the Jiaonan Belt. In the Jiaobei region, the post-Ponglai event caused local NNE-SSW kink bands and folds without association of regional metamorphism. This deformation event occurred in response to either late Triassic Indosinian orogeny or Jurassic Yanshanian orogeny.