川西炉霍地区炉霍构造带与鲜水河断裂带的转换关系及地质意义

Transformation Relationship Between LuhuoTectonic Belt and XianshuiheFracture Zoneand Its Geological Significance in LuhuoArea,Western Sichuan Province

川西炉霍地区属于马尔康-雅江复理石褶皱推覆带之主体(现一般称为雅江复理石盆地),而之后成都地质矿产所划分了较新的"炉霍构造带"这一特殊的构造单元。本文中炉霍构造带为定义的炉霍构造带侏倭-炉霍段,呈北西-南东向展布,于旦都乡东与鲜水河断裂带重合,旦都乡西侧与鲜水河断裂带分离后向北北西方向偏离。炉霍构造带形成于印支期,属于特提斯洋构造体系,而鲜水河断裂带属于新陆内构造体系,形成于燕山期,两者分属不同的构造体系,其转换时间大致是在燕山期。在炉霍-道孚地区鲜水河断裂带将炉霍构造带叠加改造而进行转换,且部分继承了早期炉霍构造带的构造形迹。本文通过炉霍地区的地震记录、力学机制等讨论两者的转换关系及其约束机制,为炉霍地区构造演化及地质灾害成因分析等领域提供新的地质依据。

TheLuhuo area in western Sichuan Province belongs to the main part of Maerkang-Yajiang Flysch Fold-nappe Belt(now commonly namedYajiang Flysch Basin).Chengdu Institute of Geology and Mineral Resources divided into a relatively new"Luhuo tectonic belt",a special tectonic unit.In this paper,The Luhuo tectonic belt is defined as the Zhuwo-Luhuo segment of the Luhuo tectonic belt,which extends in NW-SE direction,coincides with the Xianshuihe fault in the east of Dandu Township,and deviates in the NNW direction after the separation of the west side of Dandu Township from the Xianshuihe fracture zone.TheLuhuo tectonic belt was formed in the Indosinian period and belongs to the Tethyan oceanic tectonic system,while the Xianshuihe fracture zone belongs to the neocontinental tectonic system and formed in the Yanshanianperiod.The Luhuo tectonic belt and the Xianshuihefracture zone belong to different tectonic systems and their transition time is roughly in the Yanshanianperiod.In Luhuo-Daofu area,Xianshuihe fracture zone transformed the Luhuotectonic belt by superposition and transformation,and partly inherited the structural traces of the early Luhuo tectonic belt.Based on the seismic records and mechanical mechanism of Luhuo area,this paper discusses the transformation relationship and constraint mechanism of Luhuo area and provides a new geological basis for the analysis of tectonic evolution and the genesis analysis of geological disasters in Luhuo area.