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本文报道了华北克拉通西部武川西乌兰不浪地区太古宙变质基底的锆石SHRIMP年龄和Hf同位素组成。一个片麻状奥长花岗岩样品的锆石具核边结构,核部岩浆锆石和边部变质锆石的207Pb/206Pb加权平均年龄分别为2692±17Ma和2528±16Ma。对9个样品进行了锆石Hf同位素分析。新太古代早期(2692～2697Ma)片麻状奥长花岗岩(2个样品)的岩浆锆石的εHf(t)、tDM1(Hf)和tDM2(Hf)分别为4.78～8.83、2646～2780Ma和2632～2845Ma;新太古代二辉麻粒岩(2个样品)中的捕获锆石的εHf(t)、tDM1(Hf)和tDM2(Hf)分别为-2.30～8.62、2543～2954Ma和2529～3189Ma;新太古代变质深成岩(4个样品)的岩浆锆石的εHf(t)、tDM1(Hf)和tDM2(Hf)分别为-2.60～8.09、2529～2880Ma和2538～3089Ma;古元古代蓝晶石榴长英质片麻岩(1个样品)的碎屑锆石的εHf(t)、tDM1(Hf)和tDM2(Hf)分别为1.52～6.59、2432～2774Ma和2498～2925Ma。结合前人研究结果,可得出如下结论和认识:1)该区存在新太古代早期片麻状奥长花岗岩,太古宙岩石在新太古代晚期普遍遭受高级变质作用影响;2)新太古代早期为该区地壳形成主要时期,新太古代晚期则主要表现为陆壳物质再循环;3)作为阴山地块的典型代表,固阳-武川地区与华北克拉通东部太古宙基底十分类似,可能表明华北克拉通在新太古代晚期已成为统一的整体。
This paper reports the zircon SHRIMP ages and Hf isotopic composition of the Archean metamorphic basement in the West Wulanbulang, Wuchuan, western part of North China Cratonic. The zircon of a gneissic granodiorite sample has a nucleus-rimmed structure. The 207Pb / 206Pb weighted average age of magmatic zircons and marginal metamorphic zircons in cores is 2692 ± 17Ma and 2528 ± 16Ma, respectively. Nine samples were subjected to zircon Hf isotope analysis. The εHf (t), tDM1 (Hf) and tDM2 (Hf) of magmatic zircons in the late Neoproterozoic (2692-2697 Ma) gneissic granite (2 samples) are 4.78-8.83, 2646-2778Ma and 2632, respectively ~ 2845Ma. The εHf (t), tDM1 (Hf) and tDM2 (Hf) of the captured zircons in the Neo-Archean dippophase (2 samples) are -2.30 ~ 8.62, 2543 ~ 2954Ma and 2529 ~ 3189Ma ; ΕHf (t), tDM1 (Hf) and tDM2 (Hf) of magmatic zircons in Neo-Archean metamorphic diagenesis (4 samples) are -2.60 to 8.09, 2529 to 2880Ma and 2538 to 3089Ma, respectively. Paleoproterozoic ΕHf (t), tDM1 (Hf) and tDM2 (Hf) of detrital zircons of pomegranate feldspathic gneiss (1 sample) were 1.52-6.59, 2432-2774Ma and 2498-2925Ma, respectively. Based on the results of previous studies, the following conclusions can be drawn: (1) The late Neo-Archean gneissic ophiolitic granites were present in this area, and the Archean rocks were generally affected by the high-grade metamorphism during the Late Neo-Archean. (2) In the early stage of the Neoarchean, the continental crust material was mainly recycled. (3) As a typical representative of the Yinshan block, the Guyang-Wuchuan area is very similar to the Archean basement in the eastern part of the North China Craton, and may be It shows that the North China Craton has become a unified whole in the late Neo-Archean.