小秦岭楼村地区寒武系鲕粒变形有限应变测量分析及意义
Measurement and Analysis of Cambrian Oolite Finite Strain in Xiao Qinling Loucun Area and the Meaning
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摘要: 秦岭造山带中洛南-栾川断裂是划分华北板块南缘和北秦岭的重要界线.断裂带北侧楼村地区广泛出露寒武系张夏组鲕粒灰岩,鲕粒变形普遍发育.通过对变形鲕粒进行显微组构研究,在了解该地区岩石宏观变形机制及构造演化期次基础上,分别计算楼村3处测点样品的三轴比率及Flinn参数K,绘制该区岩石应变测量的Flinn图解.结果认为,鲕粒变形以单轴压扁为主(0＜K＜1),是南北向挤压应力所致,鲕粒发生单轴压扁变形是洛南小秦岭逆冲推覆构造作用的微观响应.岩石变形主要受秦岭主造山期(印支期)小秦岭逆冲推覆构造系自北向南的推覆挤压作用影响.另外,通过野外观察与邻近地区进行对比,表明洛南小秦岭逆冲推覆构造系自北向南变形增强.Abstract: Luonan-luanchuan fault is an important boundary of dividing the southern margin of NC block and North Qinling. Oolitelime of Cambrian Zhangxia group emerged widely in Loucun area north beyond the fault and oolite deformation is widely developed. By studying deformed oolite in the microcosmic way, on the base of underst anding the macroscopic deformed mechanism and structure evolution sequence, the ratioamong the three axis (X:Y:Z) and Flinn parameters (K) can be calculated and the character of oolite deformation can be known. It is indicated that oolite deformation is charact erized by monad compression (0
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