胶北蓬莱群的变形与变质及其区域大地构造意义

本文通过构造与变质研究及伊利石结晶度和同位素年龄测定。分析胶北蓬莱群的变形,变质及其区域大地构造意义。作为胶北唯一盖层的蓬莱群,在晚石炭世(299±4Ma)北北东—南南西区域挤压下首次遭受了强烈的蓬莱事件变形及低绿片岩相变质。其后的后蓬莱事件在胶北地区仅造成了局部的北北东—南南西向变形构造。作为华北板块南缘的胶北带,其上的蓬莱事件是华北与扬子板块沿胶南带碰撞的结果。这表明郯庐断裂带以东这两扳块碰撞发生在晚石炭世。在秦岭—大别山碰撞带以北的华北扳块南缘,由于碰撞也出现了类似胶北带的挤压变形。

GEOTECTONIC IMPLICATIONS OF THE DEFORMATION AND METAMORPHISM OF THE PENGLAI GROUP OF THE JIAOBEI REGION, CHINA

An investigation of the structural deformation, metamorphism, illite crystallinity, and illite K-Ar and Rb—Sr dating of the Penglai Group of the Jiaobei region provides new information which constrains its tectonic history and style. The Penglai Group, the dominant outcrop of the Jiaobei region, experienced intense deformation and low greenschist facies metamorphism during the Carboniferous (299±4Ma) under regional NNE-SSW compression. This Penglai event in the Jiaobei Belt, which is located in the southern mar- gin of the North China Plate, occurred therefore as the result of collision between the North China and Yangtze plates along the Jiaonan belt. The analyses also suggest that the collision between the two plates to the east of the Tan-Lu Fault Zone took place in the Late Carboniferous. The post-Penglai event only caused local NNE-SSW trending structures in the Jiaobei region and is interpreted as the result of either the Indosinian Orogeny or the Jurassic Yanshanian Orogeny.