Abstract: The middle Longmenshan thrust－nappe belt was developed by SE-directed compression,while the Songpan-Ganzi fold belt was subjected to NE－SW shortening. The Songpan-Ganzi foldbelt underwent four generations of deformation during middle-late stages of late Triassic : NW-trending structures were formed in D1 and deformed into acurate structures by left-lateral shearing in D2; D3 was Characterized by SE-directed thrusting, and granites intruded in D4. the middle Longmenshan thrust-nappe belt consists of Yingxiu-Beichuan, Wenchuan-Maowen, Guanxian-Anxian and Southeastern marginal nappes, and the Yingxiu－Beichuan nappe can be divided into Jiudingshan, Pengguan Complex and Tangwangzhai sub-nappes. Klippen belongs to Pengguan Complex sub-nappe. The thrust-nappe belt was propagated form NW to SE.

Key words: Longmenshan, Thrust-nappe zone, Deformational Characterlstics, Deformation Mechanism

摘要： 从龙门山推覆构造带和松潘-甘孜褶皱带的变形特征及发展过程,论证了龙门山中段推覆构造是由于其北西侧松潘-甘孜褶皱带中的北东～南西向收缩派生的南东向挤压而逐渐发育起来的。推覆作用是晚三叠世晚期以来自北西往南东逐渐扩展的,属前展式(背驮式)。

关键词: 龙门山, 推覆构造带, 变形特征, 变形机制