斜列断裂在小江断裂带内应变分配中的作用

Evolution of the strike-slip fault suggests that the en echeloned faults within the fault zone could develop to be the main faults. During our previous research, we found a newborn en echeloned fault within the Xiaojiang Fault zone- - Yiliang-Huaning Fault (Ren, 2013). The clockwise rotation of the southeastern Tibetan Plateau is consistent with the arcuate boundary fault consist of the Yiliang-Huaning Fault and northern segment of the eastern strand of the Xiaojiang Fault. This fault will definitely affect the strain partitioning within the Xiaojiang Fault zone as well as the evolution of the southeastern boundary of the Tibetan Plateau. However, we know little about it which is urgent to be known. Therefore, in this research, we will focus on the Yiliang-Huaning Fault to obtain the offset distribution, paleoseismological data following traditional active tectonics research methodology. We will synthesize our results about the Yiliang-Huaning Fault and previous results on the other strands of the Xiaojiang fault zone. Consequently, we will analysis the effects of strong earthquakes on other fault strands using coulomb stress calculation; and the strain rate variation along the fault strike using the Matlab strain program modified by our group. Finally, we will quantitatively study the stress transfer and strain partitioning of the en echeloned Yiliang-Huaning fault within the Xiaojiang Fault zone. Furthermore, we will discuss the relationship between the strain partitioning of the boundary faults, fault geometry and the deformation model of the Tibetan Plateau.

走滑断裂带发展趋势表明断裂带内部斜列分支断裂有可能是断裂发展的初级阶段，可以逐渐发展成为主要断裂。本人前期研究工作中发现小江断裂带内一条新生的斜列分支断裂- - 宜良-华宁断裂(Ren, 2013)，其与小江断裂带东支北段相连后显示为弧形，与青藏高原东南部的顺时针旋转趋势一致。该断裂对小江断裂带内的应变分配，乃至青藏高原东南边界的演化势必会造成重要影响。而该断裂的诸多基本信息均尚属未知，亟待解决。因此本研究选择宜良-华宁断裂为研究对象，拟基于传统活动构造研究方法获取的位错分布与古地震数据，结合前人在其他两主分支断裂上的研究结果，利用库伦应力计算模拟各支上强震对其他分支的作用，利用本项目组改编的应变率程序计算沿断裂带的应变率变化，量化分析宜良-华宁断裂与两主分支断裂上应力传播与应变分配情况。进一步探讨青藏高原东缘断裂几何形态、应变分配与青藏高原变形模式。

本项目基于高精度地貌数据，通过走滑断裂带滑动速率、位错分布、古地震数据等定量分析方法对走滑断裂带应变分配、强震破裂模式等进行了深入研究。除了对项目申请时所选取的小江断裂带开展了研究工作，同时还对海原断裂带上进行了深入研究。以及走滑断裂滑动速率计算方法方面进行了探讨。并受邀在Journal of Structure Geology期刊40th Anniversary Special issue 纪念专刊“Back to the Future: 40 years of Structural Geology and beyond”，系统总结了活动构造研究发展进程与未来发展趋势。编写了应变分配模拟计算程序，该代码程序主要功能为，给定断裂几何展布、产状、分段特征；通过限定区域应力场方向、区域相对运动速率，可以计算滑动速率在相应分支断裂上的分布。目前完成录入小江断裂带断裂展布信息录入，获得了初步计算结果。.取得以下三方面主要研究成果.1）走滑断裂带应变分配,.2）走滑断裂带强震破裂应变累积与强震破裂模式研究,.3）走滑断裂带滑动速率新方法..通过本项目的实施，除了对小江断裂带内部斜列分支在应变分配中作用相关结果，我们还获得了走滑断裂一系列重要认识，包括同一走滑断裂带不同段落可以有不同的强震破裂模式、滑动速率计算新方法等新认识