The metamorphic extent and age of the Susong metamorphic complex rocks ( SSMC) have been attended by manyrngeologists all along, and more controversies still exist. For this reason, three samples of garnet-mica schists from SSMC have been selected and analyzed in detail. On the basis of the analysis of petrology, the SSCM had underwent three metamorphic event, and the peak mineral assemblage includes garnet + biotite + muscovite + plagioclase feldspar + quartz + epidote + rutile + calcite + apatite. No any imprint from ultrahigh pressure or glaucophane-schiste facie metamorphism occurs. The peak P-T conditions for SSCM are T = 460 ~540℃ and P = 0. 85 ~ 1. l0GPa according to the thermodynamic appraise, which is in the range of epidote-amphibole facie. The zircon U-Pb ages from three samples in the SSCM have been divided into 4 groups, the ages from the core in zircons show three ranges of age: 2. 38 ~2. 56Ga, 1. 97 ~2. 19Ga and 0. 78 ~0. 9Ga, which reflect age of detrital zircon and imply that the SSCM have complex origin of materials. The ages from margin in zircons is in the range of 248 - 255 Ma with the 0. 01 ~0. 05 of Th/U, and the sector zoning and cloudy zoning at the margin areas of zircons have been displayed through the analysis of cathodoluminescene ( CL) images, so the zircons at margin should be metamorphic overgrowth zircons. The mean average age of 251 ± 4Ma from these metamorphic overgrowth zircons represent the peak metamorphic age for the SSCM in the light of the analysis Raman spectroscopy and petrology. Combined with the investigation from early petrology, ages and tectonic setting, the north boundary of the SSCM should be located along Iiuling-Mashigou-Shanlong.%宿松变质杂岩的变质程度和变质年龄一致为人们所关注,且争论较多.为此,本次研究选择了宿松变质杂岩中3个石榴云母片岩进行了细致的分析.岩相学分析显示,该杂岩至少经历了3期变质事件,峰期变质矿物组合为石榴石+白云母+黑云母+斜长石+石英+帘石+金红石+方解石+磷灰石,没有任何超高压或蓝片岩相变质特征的印迹.温压评价表明,宿松变质杂岩峰期变质条件为T=460～540℃和P =0.85～1.10GPa,属于绿帘角闪岩相变质范畴.对这3个岩石标本的锆石U-Pb测年研究则表明,宿松变质杂岩具有4组年龄,其中来自锆石核部的年龄有3组,年龄分别为2.38 ～2.56Ga、1.97 ～2.19Ga和0.78～0.9Ga,均为碎屑锆石年龄,反映了该杂岩的物源的构成复杂性.来自锆石边部的年龄范围为248～255Ma,其Th/U比值为0.01～0.05,均＜0.1,CL图显示边部锆石为片状和云雾状,为典型的变质增生锆石.根据矿物包裹体的拉曼光谱和岩相学分析,这些变质增生锆石为峰期变质阶段形成的,其加权平均年龄251±4Ma应为宿松变质杂岩的峰期变质时间.结合前人岩石学、年代学和构造背景的分析,宿松变质杂岩的北界应位于柳林-麻石沟-山龙一线.
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