扬子陆核古元古代变质事件——来自孔兹岩系变质锆石U-Pb同位素年龄的证据

摘要

崆岭杂岩除太古宙结晶基底外,还出露一套以含石墨和富铝矿物为特征的孔兹岩系.相对于结晶基底,目前对于该套表壳岩系的同位素年代学研究有限.对该套孔兹岩系中代表性岩石类型榴线英岩开展了变质锆石U-Pb同位素年龄测定.研究结果表明,榴线英岩变质年龄为1964±12Ma.结合前人在相近地层岩石组合中报道的锆石U-Pb年龄数据,推测崆岭杂岩孔兹岩系原岩可能沉积于2.1~2.0Ga.扬子陆核的古元古代变质-岩浆作用可能与全球广泛存在的同时期(2.1~1.8Ga)碰撞造山事件有关,暗示其很可能是Columbia超大陆的重要组成部分.%Apart from the Archean metamorphic crystal basement, a series of khondalite-bearing graphites and Al-rich minerals are exposed in the Kongling Complex. However, relative to the study of metamorphic crystal basement, geochronological studies of the supracrustal rocks are still very insufficient. In this study, the LA-ICP-MS zircon U-Pb study was carried out for the typical samples of garnet-sillimanite quartzite in the khondalite series. The result shows that the garnet-sillimanite-quartzite was metamorphosed at 1964±12Ma. Combined with the documented zircon U-Pb geochronologic data, the authors hold that the khondalite-series in the Kongling Complex was deposited at 2.1~2.0Ga. The Paleoproterozoic metamorphism and magmatism recognized in the interior of the Yangtze craton are consistent with the worldwide coeval collision-related orogenic event during 2.1~1.8Ga, indicating that this event may have been an important component in the Columbia supercontinent.