华北地台北缘中段中新元古代地块的pTt轨迹及构造演化研究

内蒙古温都尔庙至白乃庙一带分布了一系列的中新元古代地块，其变质程度均已达到角闪岩相，是研究华北地台北缘中段中新元古代构造演化的主要对象．通过对白乃庙群、乌拉乌苏斜长角闪岩地层和德言其庙岩系等不同时代典型地块的岩石组合特征和ｐＴｔ轨迹的对比研究发现，这些地块主要是拉张条件下板底垫托作用过程中形成的，与表壳岩系的绿片岩相岩石组合特征相一致，分别代表了同一拉张构造环境中不同构造层次的产物，反映了华北地台北缘在中新元古代经历了漫长的拉张过程，也是华北地台北缘遍布了支离破碎的中新元古代地块的根本原因．

pTt PATHS OF MESO-NEOPROTEROZOIC BLOCKS IN THE NORTHERN MARGIN OF NORTH CHINA PLATE AND THEIR TECTONIC INTERPRETATION

A series of Meso-Neoproterozoic blocks are distributed along Ondor Sum to Boin Sum area, Inner Mongolia. The metamorphism of these blocks has attained to amphibolite facies. They play important roles in the study of Meso-Neoproterozoic tectonic evolution of middle segment of northern margin of North China Plate. The comparison of characteristics of pTt paths and rock assemblages for typical blocks of Boin Sum Group, Amp and Deyanqimiao Formations in different times shows that they are formed under extensional conditions by underplating in Meso-Neoproterozoic. Their characteristics correspond to rock assemblages of greenschist facies of supracrustal rock. They represent respectively different tectonic levels, upper and middle crust, in the same extensional tectonic environment. It is a response of a long term extension of the northern margin of North China Plate. This is why the Meso-Neoproterozoic blocks were broken into fragments in northern margin of the North China Plate.