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秦岭石人山南缘出露一套元古代的片麻岩,在洛南—栾川断裂带的影响下经受了一系列变质变形作用。通过矿物共生组合、石英的动态重结晶型式、石英的分维数分析、石英的运动学涡度测量以及长石的有限应变测量等多种方法对石人山南缘岩石的变质变形进行了分析。结果显示由南向北随着远离断裂带,石人山南缘岩石的变质变形呈现规律性变化:表现为岩石中矿物粒径逐渐增大,形成温度逐渐增高,应变速率逐渐降低等特点。反映出随着远离洛南—栾川断裂带,变质相由绿片岩相逐渐过渡到低角闪岩相的特点,岩石退变质程度由强变弱;以剪切变形为主的岩石变形也逐渐减弱。这些现象说明了石人山岩块南缘的变质变形是受洛南—栾川断裂带的构造活动影响而形成的,反映了这一时期的宽坪岩块由南向华北板块下斜向汇聚俯冲、兼有左行走滑的构造活动对其北侧石人山岩块的影响巨大。因此,石人山岩块南缘的变质变形对研究板块俯冲过程中板缘变质变形有重要意义。
A set of metamorphic deformable deformation was exposed under the influence of the Luonan-Luanchuan fault zone in the southern margin of Shireng Mountain, Qinling Mountains. The metamorphism and deformation of the rocks in the southern margin of Shirenshan were analyzed by means of the combination of mineralogy, dynamic recrystallization of quartz, fractal dimension analysis of quartz, kinematic vorticity measurement of quartz and finite strain measurement of feldspar. The results show that the metamorphic deformation of the rocks along the southern margin of Shiren Mountains changes regularly from south to north as they are far away from the fault zone: the grain size of the rocks gradually increases, the formation temperature gradually increases, and the strain rate gradually decreases. Reflecting that the metamorphic facies gradually changed from greenschist facies to low amphibolite facies as the distance from the Luonan-Luanchuan fault zone changed, the degree of retrograde metamorphism was weakened from strong to strong, and the deformation of the rocks dominated by shear deformation gradually Weakened. These phenomena indicate that the metamorphic deformation of the southern margin of the Shirengang block is formed by the tectonic activity of the Luonan-Luanchuan fault zone, which reflects the convergence of the Kwanping block from south to north China in this period The subduction and tectonic activities with both left-lateral strike slip exert a tremendous influence on the Shiren rocks on the north side. Therefore, the metamorphic deformation of the southern margin of the Shirenshan block is of great significance for the study of plate metamorphism and deformation of the plate during subduction.