【摘要】 太华群出露于华北中部造山带南段,是研究华北克拉通南缘演化的关键地区,对其研究不仅有助于深入了解华北克拉通古、中元古代构造演化特征,对于华北克拉通东西陆块碰撞时间的厘定也具有重要意义.通过对豫西小秦岭地区太华群深熔作用形成的3类混合岩开展岩相学研究,发现深熔作用对岩石的改造是不均匀的,明显受到了原岩的物质成分、岩石的结构构等性质的制约.通过对岩浆锆石及深熔锆石进行LA-ICP-MS定年,确定小秦岭地区太华群混合岩原岩年龄为早古元古代,深熔作用发生时间约为1.8Ga.研究区混合岩形成于华北克拉通东、西陆块碰撞后的伸展阶段,与区域同时期形成的大量基性岩墙群及A型花岗岩共同记录了华北克拉通在1.8Ga前后发生的大规模伸展拉张事件.更多还原

【Abstract】 The Taihua Group,exposed in the southernmost terminal Trans-North China Orogen(TNCO),is important for deciphering the mysterious evolution processes of the southern margin of the North China Craton during Proterozoic,and determination of the collision time of the eastern and western blocks of the North China Craton.Petrological study on three kinds of migmatites formed by anatexis from the Taihua Group in Xiaoqinling area,West Henan,indicates that the transformation of migmatites caused by anatexis is uneven,which is obviously limited by the composition of protolith,structure of rocks and other properties.LA-ICP-MS U-Pb dating of the anatexis zircons shows that the protolith crystallized in the Paleoproterozoic and the anatexis occurred at about 1.8Ga.The migmatites and contemporaneous mafic dike swarms and A-type granite in the study area were generated in a post-orogenic,extensional environment following continent-continent collision at 1.85 Ga between the eastern and western blocks of the North China Craton.更多还原