四川九寨沟地区古应力测量和分析.doc

四川九寨沟地区古应力测量和分析

【摘要】 古应力重建是研究区域构造演化的一个重要方法。三清山地区位于秦岭造山带的南缘，先后受到秦岭造山带、龙门山和大巴山等构造的控制。本文根据野外露头，重点研究三清山地区发育的三大主要断裂带（大河－杨坝－竹坝断裂、正源－水磨－上两－官坝断裂、牟家坝断裂）,对断层面的古应力标记、产状进行详尽的观测，并利用Angelier等提出的古应力分析方法及相关的配套软件对野外实测数据进行分析，作出古应力图，恢复出该地区的构造演化。结果显示，本区发育三组不同性质的断裂。在印支-燕山期，本区主要是受到秦岭巨型推覆构造控制，在南北向挤压应力的作用下，发育了一组顺层滑动的逆断裂；在喜马拉雅期，由于龙门山推覆构造的影响，区域上受到北西-南东向的挤压作用和北东-南西的拉伸作用而发育有一系列走滑断层；最晚期的正断裂体现出来的拉张作用推测与本区推覆构造形成后期的滑脱作用有关。

【关键词】 断裂带 野外测量  古应力分析  三清山

【Abstract】 Paleostress reconstruction is an important way to research regional tectonic evolution. Micangshan locates at southern part of Qinling orogenic belt, and its tectonic frame is mainly controlled by Qinling orogenic belt, Longmenshan and Dabashan. This paper focus on three faults zones (i.e. Dahe-Yangba-Zhuba fault, Zhengyuan-Shuimo-Shangliang-Guanba fault and Mojiaba fault) in this area. Detailed paleostress measurement was done first in field work. The measured data were then processed and plotted following the paleostress analysis method given by Angelier. The results show that there are three groups of faults in this area. In Indosinian-Yanshan period, this area is mainly controlled by Qinling giant nappe structure and a group of inverse faults along the strata plane were formed under the SN strike stress. In Himalayan period, under the influence of Longmenshan nappe structure, a group of strike-slip faults was formed in this area. The last group of faults, which is also the latest, was supposed to be related to the decollement process of the nappe structure in this area.

【Keywords】 Fault Zone  Field Measurement  Paleostress Analysis  Sanqingshan
 
目录
1 引言 1
1.1 研究的目的和意义 1
1.2 研究现状 1
1.3 研究思路 1
2 区域地质概况 1
2.1 地层 1
2.2 构造背景 1
2.4 地质发展史 2
3 古应力恢复的原理和方法 2
3.1 断层及其分类 2
3.2 断层盘上的标识 2
4 三清山地区古应力测量及分析 3
4.1 野外工作概况和实测数据 3
4.2 古应力分析 3
5 三清山地区古应力测量分析所揭示的区域构造意义 4
6 结论和建议 4
6.1 结论及认识 4
6.2 工作建议 4
致谢 4
主要参考文献 i