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对南秦岭佛坪地区麻粒岩相岩石中锆石的特征进行了详细的研究和U-Pb同位素年龄测定。中酸性麻粒岩中3个变质成因锆石的~(256)Pb/~(238)U表面年龄统计权重平均值(谐和年龄)为221.4±3.6Ma,是这些变质锆石较为准确的生成年龄;该样品4个锆石颗粒组成的不一致线上、下交点年龄分别为822±272Ma和218±14Ma;石榴夕线黑云片麻岩中4个锆石颗粒构成的不一致线的上下交点年龄分别为2283±162Ma和271±15Ma。两个样品的数据点均比较靠近下交点而远离上交点,其上交点年龄不具明确地质意义。综合各方面因素,认为麻粒岩相峰变质作用时代为印支期—海西晚期(220～270Ma左右),这是迄今为止秦岭地区所报道过的最年轻的麻粒岩地质体。
The characteristics of zircons from granulite facies rocks in Foping area, southern Qinling were studied in detail and the U-Pb isotopic ages were measured. The statistical weighted mean (harmonic age) of ~ (256) Pb / ~ (238) U surface ages of the three metamorphic zircons in the intermediate-acid granulites is 221.4 ± 3.6Ma, which is the most accurate proxy for these metamorphic zircons Age. The in-line and down-crossing ages of the four zircon grains in this sample are 822 ± 272Ma and 218 ± 14Ma, respectively. The upper and lower intersections of the inhomogeneous lines formed by four zircon grains in the gneiss line Respectively 2283 ± 162Ma and 271 ± 15Ma. The data points of the two samples are all located closer to the lower intersection and far away from the upper intersection, the age of the upper intersection does not have clear geological meaning. Based on various factors, it is believed that the granulite-facies metamorphism is the Indosinian-Late Hercynian period (about 220-270 Ma), which is the youngest granulite geologic body ever reported in Qinling area.