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东秦岭商丹地区武关岩群鮸鱼咀斜长角闪岩单元中的斜长角闪片岩缺乏较为精确的年代学资料,制约着对武关岩群形成时代及其构造属性的认识。利用LA-ICP-MS锆石U-Pb同位素测年技术对武关岩群中斜长角闪片岩进行锆石U-Pb年龄测定,所得年龄数据显示出大致5组年龄,分别为~2.45Ga,~1.7~2.0Ga,~0.95Ga~0.85Ga,~0.71~0.74Ga,除年龄值最新的一组锆石外,其余锆石均属于斜长角闪片岩的原岩岩浆在上升过程中捕获自地壳物质的继承锆石,记录了南秦岭地区基底增长的过程。据此认为斜长角闪片岩的原岩(玄武岩)的形成时代应为~730Ma,与新元古代中晚期Rodinia超大陆的裂解有关。
The absence of more accurate geochronological data in the plagioclase amphiboles in the Guantuchang amphibolite unit in the Wuguan Group in the Shangqin area of East Qinling lags far behind the understanding of the formation age and the tectonic attributes of the group. U-Pb dating of plagioclase amphiboles in the Wuguanyan Group was determined by LA-ICP-MS zircon U-Pb zircon dating. The age data obtained showed roughly 5 groups of ages, ~2.45Ga ~ 1.7 ~ 2.0Ga, ~ 0.95Ga ~ 0.85Ga and ~ 0.71 ~ 0.74Ga, respectively. Except for a group of zircons with the most recent age value, all the other zircons belong to plagioclase feldspathic rocks. Zircon inherited from the material recorded the process of substrate growth in the southern Qinling area. Therefore, the formation age of protolith (basalt) of the plagioclase feldspars should be ~ 730Ma, which is related to the cracking of the Rodinia supercontinent in the middle and late Neoproterozoic.