【作者】 李佐臣；

【导师】 裴先治；

【作者基本信息】 长安大学 ， 构造地质学， 2006， 硕士

【摘要】 龙门山构造带位于扬子地块西北缘，处于上扬子地块（四川盆地）—碧口微地块—松潘—东西秦岭交界区域，是中国大陆构造中的主要构造结之一，也是青藏高原东部边缘地带，是诸多地块和不同类型造山带汇聚交接地区，具有复杂的构造图象和拼合历史。 本文在宏观掌握扬子地块西北缘后龙门地区及邻区最新研究成果和研究进展基础上，重点收集区域有关地层学、岩石学、岩石地球化学、构造地质学以及同位素年代学等方面的研究成果。野外地质工作采取“点—线—面”相结合的调研方法，选择关键地区进行重点精细构造研究，关键部位结合已经收集到的1：5万地质图进行小范围大比例尺面积性填图研究、构造解析和精细解剖。 在系统总结前人研究成果的基础上，通过野外观察、测量、分析及室内的整理，得出以下几点结论及新认识。 1、通过前人对变质核杂岩构造特征的总结，确认了扬子地块西北缘轿子顶变质核杂岩的存在。在此基础上对组成轿子顶变质核杂岩的各部分进行了比较详尽的描述，并认为轿子顶变质核杂岩具有三层结构模式，即①变质核；②滑脱层（固态流变中间层）；③盖层。在变质核、滑脱层和盖层之间及内部发育有不同级别的层间拆离滑脱带。 2、各种构造现象表明研究区主要受到了三期变形，第一期为以顺层透入性面理（S₁）、顺层掩卧褶皱、顺层剪切褶皱、拉伸线理等为代表的伸展体制下形成的构造变形，第二期以非透入性的轴面劈理（S₂）、不对称褶皱、皱纹线理等为代表的由北西向南东逆冲推覆构造引起的变形。局部发育的以青川断裂左行走滑引起的褶劈理（S₃）代表更晚期的构造变形。 3、根据变质核杂岩内部两期构造叠加关系、区内发育的逆冲断层与滑脱断层的交切关系以及岩体与断裂的切割关系等，认为具有伸展构造背景的滑脱断层的形成时代早于逆冲推覆构造，且滑脱断层时代早于220Ma。结合前人的研究成果，认为轿子顶变质核杂岩构造形成的下限为二叠世，上限为晚三叠世早期。 4、轿子顶变质核杂岩的南北两侧被两条低角度拆离断层所限，两条断层分别向两个方向倾斜，线理的运动指向也指向相对的方向，说明轿子顶变质核杂岩为对称型变质核杂岩。更多还原

【Abstract】 Longmen Mountains tectonic belt is located at the northwest margins of Yangtze block. It is at the joint of Early Yangtze block (Sichuan Basin)-Bikou microblock-Songpan-Eastern and Western Qinling. It is one of the major tectonic knots in China’s continental tectonics, and also at the eastern margins of the Qinghai-Tibet Plateau. It is the convergent conjoin area of many plates and different type orogenic belts and has a complex structural image and assembly history.This dissertation collects mainly regional research achievements of stratigraphy, petrography, lithogeochemical , structural geology and isotopic chronological et al. on the basis of mastering the new research findings and progress of the Longmen Mountains area at the northwest margins of Yangtze block . Field geological work takes "point-line-side" combining research method to carry through focus refined tectonic studies choosing the key areas. the key parts carry through small areas and large scale mapping studies, analytical tectonics and fine dissection combining with 1:5 million scale geological maps.This study reachs the main points of our research include following several conclusions and the new understanding through the field observation, the survey, the analysis and the room reorganization summing up the predecessor outcome.1. Through the predecessor sum-up of the structural characteristics of metamorphic core complex, confirmed Jiaoziding metamorphic core complex existence at the northwest margins of Yangtze block. On this basis the article describs detailedly each parts composing Jiaoziding metamorphic core complex and thinks that Jiaoziding metamorphic core complex has three-layer structure patterns, namely (1)the metamorphic core; (2) the surge layer (the middle solid rheologic ductile layer) ; (3)the cover.layer between and among the different levels of development within a layer down from causing belt. And the three layers divided by basement denudational更多还原