阿尔金山喀腊大湾地区变形岩石EBSD组构分析

EBSD Fabrics Analysis of Deformed Rocks from Kaladawan Area,Altun Mountains,NW China

岩石组构是指组成岩石的矿物在岩石中分布的各向异性，EBSD （Electron Back Scattered Diffraction）岩组分析就是运用电子背散射衍射技术测定岩石结构要素---岩石中矿物分布的规律性。本文作者运用EBSD技术方法，对阿尔金山喀腊大湾地区变形岩石的组构分析显示，花岗质糜棱岩和蚀变变形花岗岩中，石英变形机制是以中温I级柱面（10-10）＜0001＞和中高温II 级柱面（10-10）＜0001＞滑移为主，少量为中低温底面（0001）＜11-20＞滑移；而在变形火山岩中，石英变形机制是以中低温底面（0001）＜11-20＞滑移系为主。在区域南北向剖面分布上，接近阿尔金北缘断裂和白尖山断裂的中北部变形温度较高，向南变形温度有逐渐降低的趋势。从岩石组构特点结合宏观构造分析，可以认为本区北段属于中-中深层次（15～25km，t＝350～550℃，P＝0．40～0．60GPa）的韧性变形，而中南段为中浅层次（10～15km，t＝250～350℃，P＝0．25～0．40GPa）的韧脆性变形。结合不同变形特点花岗岩的年代学资料，确定构造变形的时代为早古生代。上述特征与区域上发育板块碰撞带，且北部发育高压榴辉岩和蓝片岩的构造部位以及该构造变形带的演化历史相吻合。

Petro-fabrics means an anisotropy of rock-forming minerals distribution.EBSD petro-fabrics analysis is a method to measure the distribution pattern of rock texture factors-minerals by means of Electron Back Scattered Diffraction system to plane net of a special mineral crystal.Based on the EBSD petro-fabrics analysis of deformed rocks from Kaladawan area,Altun Mountains,NW China,the authors draw the conclusion as follows.①There happens a strong deformation in the rocks from the area.②Quartz in granitic mylotite and altered deformed granite is mainly deformed along its prismatic I and II glide system and partly along its basal or basal-near glide system,while Quartz in deformed volcanic rocks is mainly deformed along its basal or basal-near glide system.③The deformations of the rocks from the northern part of the area happen under a medium and medium-deep depth of 15~25km,a middle and med-high temperature of 350~450℃ and a middle pressure of 0.40~0.60GPa,while the deformations of the rocks from the southern part of the area happen under a low-medium depth of 10~15km,a low-middle of 250~350℃ and a low-middle pressure of 0.25-0.40GPa.④Combine with the age of different deformed granite,the authors conside that the ductile deformation in the area was happened in early Paleozoic era. All features above are identical to specious position that they are located the convergent plate collision belt and the distribution of high-pressure eclogite and glaucophane schist and to their evolution history.