豫西小秦岭地区晚古元古代地壳深熔作用及 构造意义:岩石学和锆石U-Pb年代学证据
Late Paleoproterozoic Crustal Anatexis and Its Tectonic Significance: Evidence from Petrology and Zircon U-Pb Ages of Migmatite from Xiaoqinling Area, West Henan

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
The Taihua Group, exposed in the southernmost termina1 Trans-North China Orogen(TNC0), is important for de- ciphering the mysterious evolution processes of the southern margin of the North China Craton during Proterozoic, and deter- mination of the co11ision time of the eastern and western b1ocks of the North China Craton. Petro1ogica1 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 obviouslylimited by the composition of protolith, structure of rocks and oth- er properties. LA-ICP-MS U-Pb dating of the anatexis zircons shows that the protolith crysta11ized in the Paleoproterozoic and thc anatcxis occurrcd at about1.8 Ga. Thc migmatitcs and contcmporancous mafic dikc swarms and A-typc granitc in thc study area were generated in a post-orogenic, extensiona1 environment fo11owing continent-continent co11ision at1.85 Ga between the eastern and western b1ocks of the North China Craton