元谋断裂带(晚)新生代构造应力场浅析

Tectonic Stress Field on the Yuanmou Fault Zone during the(Late) Cenozoic

活动断裂带是形迹组合、构造地貌特征及力学性质相呼应的构造体系。以元谋断裂带(晚)新生代地层内发育的构造透镜体、剪节理、张性裂隙等形迹组合及其发育序列为研究对象,通过吴氏网下半球赤平投影、节理玫瑰花图及张性裂隙性质分析等研究方法,推测元谋断裂带自(晚)新生代以来主要受早期的北北东-南南西向和晚期(元谋运动之后,约80万年)的北北西-北西西向水平主压应力场作用,改变了构造活动性质并确立了现在的构造形迹、地貌。

The feature of active fault zone is generally characterized by echoing each other among structure assemblages, landform and mechanical properties. In this study we measured the tectonic lenticularbodies, shear joints and tensional fracture developed in the fault zone in the field, and then we projected the measurements into WulffNet with lower hemisphere, and made rose diagram of joint and tensional fracture. The studied results show that horizontal principal stress is in the NNE-SSE direction during early period and horizontal principal stress is in the NNW-NWW direction during late period （after Yuanmou Motion, about 0.8Ma ago）. Such stress field has the great effect on not only the activity of Yuanmou fault, but also the current characteristics of tectonics and landform.