【作者】 何国琦； 李茂松；

【Author】 He Guoqi Li Maosong (Department of Geology,Peking Univercity,Beijing)

【机构】 北京大学地质学系；

【摘要】 对中国兴蒙-北疆地区蛇绿岩的研究,使我们对蛇绿岩的地质特征、产出状态和形成原因有了一些认识．在某些地区蛇绿混杂岩带有成对分布或多条相伴出现的现象,这种现象在世界范围内也较普遍．文中讨论了不同产状的蛇绿岩带在构造分区中的意义．蛇绿混杂岩带在平面上呈环状或半环状分布,其成因往往与大规模推覆作用的改造有关,复杂的低角度的辗掩断层把包含有蛇绿岩的外来岩块散布到一个相当大的区域内．一些冷侵位的超镁铁岩体成群成带分布,但带内不包含蛇绿岩套的其它组分,这可能是在裂谷作用后期的挤压阶段,水化的超镁铁岩以构造流的形式沿断裂侵位到地壳上层所致．中国北方及邻区具有一级构造分区意义的蛇绿岩带有三条：查-阿-南蒙蛇绿混杂岩带、南天山蛇绿岩带、恩格尔乌苏蛇绿混杂岩带．更多还原

【Abstract】 Through a study of the ophiolitea in the Hinggan-Inner Mongolia-North Xinjiang region of China,the authors have gained further knowledge of the geological features,oc- currence and origin of ophiolites.Some paired ophiolitic mélange belts have been found in the area.This may be related to good development and preservation conditions of fore-arc and back-arc ophiolites.In addition,the disintegration and reassembling of continental margins could also form two or more ophiolite belts which were formed and emplaced al- most at the same time.This feature may have certain universal significanee.Ophiolite belts may occur in groups or rings or half rings in plan,They are usually related to large-scah overthrusting in origin.Complex low-angle overthrust faults brough exotic blocks contain- ing ophiolites to a wide region.Some tectonically emplaced ultramafic rock bodies occur in groups.They usually do not contain other components of ophiolites.It is possible that hyd- rated ultramafic rocks were emplaced as tectonic flows along faults to upper levels of the crust in late compression stage of rifting.There are three ophiolite belts that are of signif- icance in the first order tectonic division in northern China and its adjacent:the Charsk- Armantai-south Mongolia ophiolitic mélange belt,south Tianshan-Beishan ophiolitic mélange belt and Engger-Us ophiolitic melange belt.更多还原