张八岭推覆体特征及其成因机制

GEOMETRY AND MECHANICS OF ZHANGBALING NAPPE IN EAST OF TANLU FAULT ZONE,EASTERN CHINA

张八岭推覆体位于扬子板块的前陆地带，属皖南推覆构造的一个单元，沿ＮＮＥ向延伸。根据地质、钻探及地球物理等资料，可确定张八岭推覆体为一向东南推覆的复合叠置构造，其推覆距离大于１６ｋｍ，是中生代华北与扬子两板块陆陆碰撞造山作用的产物。

The Zhangbaling nappe lies in the northern margin of the South China block, east of the Tanlu fault zone. It belongs to the western part of fold and thrust tectonics of the Lower Yangzi area with a trend of NNE. The Dabie belt is to its northwest and Chuxian Susong tight fold and thrust belt is to its southeast. It covers an area of about 1100 km 2. According to the levels of thrusts and types of folds,the Zhangbaling nappe can be divided into the Feidong nappe and the Shiji nappe. Based on data of field observation, drills and geophysics,the authors demonstrated that the Zhangbaling thrust nappe is a complex thrust structure with a movement more than 16 km southeastward. The isotope age of its granites and metamorphic belts is commonly 165～240Ma. This suggests that it was shaped during the early Mesozoic time when the North and South China blocks collided. After it was formed, the Tanlu fault, which is left lateral slip, destroyed its integrity. Therefore,the Tanlu fault zone is not its northwest boundary. It is suggested that the western boundary of the Zhangbaling nappe is located in the south of Dabie block.