中文摘要：

根据锆石SHRIMP和单颗粒逐层蒸发法的研究．初步确定了内蒙古阿拉善地区早前寒武纪变质岩系的形成时代。迭布斯格岩群下部依肯乌苏岩组的形成时代为2700Ma左右．并经历了新太古代晚期和古元古代末两期变质改造，同时在其中发现了目前该区最老的3．5Ga的残留碎屑锆石。巴彦乌拉山岩组形成于2500～2264Ma．属于古元古代。在阿拉善岩群中获得了1367Ma和1617Ma的离子探针分析结果．因此不能排除部分阿拉善岩群属于中元古代的可能性。初步的同位素年代学研究表明，该区的变质岩系由不同时代的多套变质岩系组成．具有各自的组成特点．应将它们划分开。

英文摘要：

The formation ages of the early Precambrian metamorphic series in the Alxa area, Inner Mongolia, have preliminarily been determined using the zircon SHRIMP U-Pb and single-zircon stepwise evaporation methods. The Yiken Us Formation-complex in the lower part of the Debusige Group-complex formed ～2700 Ma ago and underwent two phases of metamorphism in the late Neoarchean and at the end of the Paleoproterozoic. The oldest （3.5 Ga） detrital zircons in the area have been found in the formation-complex, suggesting that older crustal material probably exists in the area. The Bayan U1 Formation-complex formed in the period of 2500-2264 Ma and is considered to be of Paleoproterozoic age. SHRIMP ages of 1367 and 1617 Ma have been obtained for detrital zircons in the Alxa Group-complex, which means that the possibility that the Alxa Group-complex might belong to the Mesoproterozoic cannot be ruled out. Isotope chronological studies indicate that the Precambrian metamorphic series in the area consists of several metamorphic series of different ages and geneses, which have their own compositional characteristics, so they should be subdivided into the Neoarchean Debusige Group-complex, Paleoproterozoic Bayan U1 Formation-complex and Paleo- and Mesoproterozoic Alxa Group-complex.