【摘要】 位于胶北带的蓬莱群是鲁东残留于太古宙—早元古代结晶基底之 上唯一的盖层。其沉积时代和变形、变质时代过去一直是未解决的问 题。本文报道并解释了从蓬莱群板岩中新获得的全岩Rb-Sr年龄、伊 利石-全岩对Rb-Sr年龄和伊利石K-Ar年龄。 在对样品的构造、变质研究和伊利石结晶度、X射线衍射及扫描电 镜分析的基础上,所得473±32Ma(奥陶纪)的全岩Rb-Sr年龄被解 释为蓬莱群遭受埋藏变质的中止时间。因此蓬莱群是老于奥陶纪的地 层。蓬莱群的第一期褶皱和同构造低绿片岩相变质(即蓬莱运动),发生于299±4Ma以前,即晚石炭世。处于华北板块南缘上胶北带的蓬莱运动,是华北和扬子板块沿胶南带碰撞的结果。这表明郯庐断裂以东华北与扬子板块的陆-陆碰撞发生在晚石炭世。这一碰撞事件在秦岭-大别山-胶南碰撞带以北的华北板块南缘带中都造成了近南北向挤压变形。更多还原

【Abstract】 The Penglai Group in the Jiaobei Belt is the only cover of the Archaean to Early Proterozoic crystalline basement in East Shandong. The ages of deposition of the Penglai Group and of its deformation and metamorphism have long been a subject of speculation. Whole-rock Rb-Sr ages, illitewhole-rock pair Rb-Sr ages and illite K-Ar ages obtained from the Penglai Group slates are reported and interpreted in this paper. According to structural and metamorphic studies, and illite crystalli-nity, XRD and SEM analyses, a whole-rock Rb-Sr age of 473±32Ma (Ordovician) is interpreted as the time of burial metamorphism experienced by the Penglai Group. Therefore, the age of the Penglai Group is older than Ordovician. The first-phase folding and syntectonic lower greenschist-facies metamorphism in the Penglai Group, i.e. the Penglai Movement, took place before 299±4Ma B.P. i.e. in the Late Carboniferous. The Penglai Movement that occurred in the Jiaobei Belt on the southern margin of the North China Plate is attributed to the collision between the North China and Yangtze Plates along the Jiaonan Belt. This demonstrates that the continent-continent collision between the North China and Yangtze Plates to the east of the Tan-Lu Fault Zone took place in the Late Carboniferous. The collision caused N-S compression and deformation in the southern margin belt of the North China Plate to the north of the Qinling-Dabieshan-Jiaonan collision Belt.更多还原