阿尔金北缘岩石变形机制——来自X光组构分析的证据
Rock deformation mechanism of northern Altun margin-Evidence from X-ray fabric analysis
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摘要: 对阿尔金北缘地区变形蚀变花岗岩、花岗质糜棱岩、变形酸性火山岩和变形英安质凝灰岩中石英和绢云母2种矿物进行X光岩石组构分析, 认为本区岩石变形比较明显, 宏观面理近于东西向展布, 绢云母变形较强, 平行于面理定向排列; 而石英以底面或近底面滑移为主, 部分样品兼有柱面Ⅰ型滑移和柱面Ⅱ型滑移, 反映本区岩石变形机制为中浅层次的脆-韧性变形(10~15km、250~350℃、0.25~0.40GPa)。通过岩石组构特征与宏观面理产状, 推断本区韧性变形以右行运动为主, 与板块碰撞在阿尔金北缘大平沟地区产生的韧性变形带特征一致。Abstract: This paper reports the geological tectonic settings and regional stratigraphic rocks of northern Altun marginal area. Based on the quartz and sericite X-ray perofabrics analysis of altered deformed granite, granitic mylotite, deformed acidic volcanic rock and deformed dacitic tuff from this area, the authors have drawn the following conclusions:①The rock deformation of this area is relatively apparent; ②Sericite is parallel to the schistosity and shows a great orientation in the alignment which reflects the strong deforma-tion along the EW-trending tectonic deformed belt; ③Quartz is mainly deformed along its basal or basal-near glide system and is combined with prismaticⅠandⅡglide system; ④The deformation mechanism of northern Altun area happened at a medium-shallow depth of 10~15km with a low-middle temperature of 250~350℃and a low pressure of 0.25~0.40GPa; ⑤According to the features of X-ray perofabrics analysis and schistosity, the authors hold that this ductile deformation moved in a right-lateral way. All this is consistent with the features of ductile-brittle deformation zone formed by plate collision belt and oceanic crust closure in Dapinggou area of northern Altun.