摘要
洛南—栾川断裂带是秦岭造山带中一条著名的断裂带，是华北板块与秦岭造山带的地质分界线，其走向近东西，断裂带发育有宽坪岩群和陶湾岩群等岩石，洛南—栾川断裂带的构造作用过程及其演化对这些岩石的变形起了重要作用。因此，分析断裂带岩石的变形特征及其形成条件对于探讨洛南—栾川断裂带的构造环境以及分析古板块汇聚边界变形有重要意义。本文以洛南—栾川断裂带栾川段为主要研究对象，通过室内外变形研究及多种测试分析，认为洛南—栾川断裂带基本走向为290°，倾角为58°～89°，糜棱面理、矿物生长线理和褶皱普遍发育，具有由南向北的俯冲兼有左行平移的运动学特征。断裂带内岩石变形强烈，变形矿物主要为石英、方解石、黑云母和白云母。变形机制：石英以膨凸式和亚颗粒旋转动态重结晶为主，方解石以机械双晶和亚颗粒旋转变形为主，云母变形以应变滑劈理为主。在宽坪岩群北侧和陶湾岩群南侧主要为塑性变形，在陶湾岩群北侧主要为脆性变形。分别对应于洛南—栾川断裂带第2期由南向北的俯冲走滑构造活动和第4期由北向南的脆性逆冲推覆构造活动。通过方解石机械双晶、多硅白云母压力计、黑白云母Ti温度计、斜长角闪温度计等方法分别对洛南—栾川断裂带（栾川段）的形成环境进行了分析，得到矿物变形温度为440℃～509℃， 压力为0.4～1.4 GPa， 差异应力为0.27～0.426 GPa， 即韧性剪切带的形成环境属中温、中压条件。因此，本文认为洛南—栾川断裂带（栾川段）变形环境为中温、中压，相当于地壳浅层的构造变形环境。
Luonan-Luanchuan fault belt is a famous fault zone of the Qinling orogenic belt, which is the geological boundaries of the North China plate and Qinling orogenic belt. The strike nearly EW to fault zone developed Kuanping Group and Taowan Group rocks. The process and evolution of the rock deformation play an important role. Therefore, the analysis of the deformation characteristics of rock fracture zone and formation conditions has important significance to investigate the Luonan-Luanchuan fault belt tectonic environment and analysis ancient convergent plate boundary deformation. This paper uses Luonan-Luanchuan fault belt Luanchuan structural section as the main object of study. Through the indoor and outdoor deformation of a variety of research and test analysis, it considers the basic trend of Luonan-Luanchuan fault belt is 290° with an angle of 58°～89°. And the mylonitic foliation, mineral lineation and folds developed widely, with left lateral movement and northward subduction. The main deformation mines are quartz, calcite, biotite and muscovite. The deformation mechanism is dominated by quartz bulging and subgrain rotation of dynamic recrystallization,calcite mechanical twinning and subgrain rotation deformation. The mica deformation is mainly in strain slip cleavage. The north of Kuanping Group rock and the south of Taowan Group are plastic deformation,and the north side of the Taowan Group is brittle deformation. It correspond to Luonan-Luanchuan fault belt with the second period of northward subduction strike slip tectonic activity and the fourth period of the brittle reverse thrust nappe tectonic activity from north to south. By using mechanical twinning of calcite, muscovite pressure meter,biotite and muscovite Ti thermometer,amphibolite thermometer,we get the mineral deformation temperature of 440℃～509℃,the pressure is 0.4～1.4 GPa and the differential stress is 0.27～0.426 GPa. Namely the formation environment of the ductile shear zone belongs to medium temperature and medium pressure c
出处
《地质科学》
CAS
CSCD
北大核心
2016年第4期1074-1089,共16页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金项目（编号：41572177,41272213,41072161）和教育部博士点基金项目资助.
关键词
秦岭造山带
洛南—栾川断裂带
变形特征
变形机制
变形环境
Qinling orogenic belt
Luonan-Luanchuan fault belt
Deformation characteristics
Deformation mechanism
Deformation environment
