内蒙古阿拉善左旗巴音诺尔公NNE向韧性剪切带研究

发布时间：2018-04-26 07:49

  本文选题：阿拉善 + 韧性剪切带　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：巴音诺尔公地区NNE向韧性剪切带位于内蒙古阿拉善左旗巴音诺尔公南部,长约17km,宽约5km。在剪切带的北部及中部糜棱面理倾向南东,倾角55°~85°,南部糜棱面理倾向南西,倾角70°~87°。糜棱岩带自西向东划分为糜棱岩化带—糜棱岩带—初糜棱岩带(弱—强—弱)。带内发育的糜棱面理、拉伸线理、S C构造、旋转残斑、书斜构造、“云母鱼”等宏观及微观构造,平面上呈现左行剪切特征,剖面上呈现上盘(东盘)下降的运动方式。利用矿物温度计、EBSD石英C轴组构综合分析该韧性剪切带的温度在250~530℃区间内,存在两个温度区间即500°~530°(早期剪切阶段)与250°~300°(晚期剪切阶段),围压为200~400MPa。推断剪切带形成于8~16Km的深度范围内。差应力值为:44.31~97.94MPa,应变速率为10-14 s-1(300℃)和10-11 s-1(500℃)。糜棱岩带的涡度值W_k=0.94,显示剪切带晚期阶段主要为简单剪切。使用S C面理法计算出的剪应变值为0.7。按变形带宽度平均值2000m计算,同时不考虑该韧性剪切带的体积变化,糜棱岩带的剪切位移量为1400m。韧性剪切带的剪切运动分为两个阶段,结合U Pb锆石LA ICP MS法年龄测试资料,形成结果为:中高温变形阶段为三叠纪的早期,低温变形阶段为三叠纪早期到白垩纪早期。
[Abstract]:The NNE ductile shear zone is located in the southern part of Bayinnuogong, Alashan left Banner, Inner Mongolia, with a length of about 17 km and a width of about 5 km. In the northern and middle part of the shear zone, the surface of the mylonian tends to the south east, with a dip angle of 55 掳/ 85 掳, and the southern surface of the ridge tends to the south west with a dip angle of 70 掳/ 87 掳. The mylonite belt is divided from west to east into mylonium-mylonite zone and primary mylonite zone (weak-strong and weak-mylonite zone). The microcosmic and macroscopic structures, such as metagonal texture, extensional lineal tectonics, rotational speckles, diagonal structures, "mica fish" and so on, are developed in the belt. They show left-row shear characteristics on the plane and downward motion on the upper (eastern) face on the section. The temperature of the ductile shear zone in the temperature range of 250 鈩，

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