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太华变质杂岩出露于华北克拉通中部造山带最南缘,整体呈近东西向展布。华山地区的太华变质杂岩区岩性复杂多样,保存了至少三个阶段的变质矿物组合。本文对其中的黑云斜长片麻岩和黑云二长片麻岩中的锆石,进行了详细的LA-ICP-MS U-Pb定年;对斜长角闪片麻岩中的变质角闪石,进行了常规40Ar/39Ar定年。定年结果表明:(1)黑云斜长片麻岩中的碎屑锆石记录了两期(~2.3Ga和~2.5Ga)明显的岩浆事件,变质锆石记录了一期(1.87~1.85Ga)变质事件;(2)黑云二长片麻岩中的岩浆锆石U-Pb年龄为2.33Ga和2.31Ga,变质锆石记录的变质年龄为1.96Ga;(3)两个斜长角闪片麻岩样品中,变质角闪石的40Ar/39Ar坪年龄和等时线年龄说明,该地区经历了一期~1.8Ga的变质热事件。这些数据说明,太华变质杂岩也记录了华北克拉通东部陆块与西部陆块之间的碰撞造山过程,不过比中部造山带其它变质杂岩区记录的时间更早,变质作用持续的时间也更长。这暗示了该地区在1.96~1.80Ga期间,经历了一次比较漫长而复杂的构造-变质演化过程。
The Taihua metamorphic complex is exposed in the southernmost part of the orogenic belt in the central part of the North China Craton, with an overall east-west distribution. The Tahua metamorphic complex in Huashan area is complex and diverse in lithology, preserving at least three stages of metamorphic mineral assemblages. In this paper, the LA-ICP-MS U-Pb dating of zircons in the biotite plagiogneiss and biotite gneisses is carried out in detail. For the metamorphic angle Amphibole, a conventional 40Ar / 39Ar dating was performed. The dating results show that: (1) detrital zircons in the biotite plagioclase gneiss have recorded two distinct magmatic events (~2.3Ga and ~2.5Ga), metamorphic zircons have recorded a period of 1.87 ~ 1.85Ga ) Metamorphic events; (2) the magmatic zircon U-Pb ages in the biotite gneiss are 2.33Ga and 2.31Ga, metamorphic zircons record a metamorphic age of 1.96Ga; (3) In the gneiss samples, the 40Ar / 39Ar plateau and isochron age of the metamorphic hornblende indicate that the region experienced a ~ 1.8Ga metamorphic event. These data indicate that the Taihua metamorphic complex also records the collision orogeny between the eastern and western terranes of the North China Craton, but records earlier than other metamorphic complex areas in the central orogenic belt and lasted for the duration of metamorphism Also longer. This suggests that the region experienced a long and complex tectono-metamorphic evolution from 1.96 to 1.80 Ga.