Abstract The North China Craton (NCC) is characterized by major ca. 2.5 Ga tectonothermal events, which is markedly different from most other typical cratons worldwide. Whereas, ca 2.7 Ga rocks are sporadically exposed in the whole craton, and only have been identified in several localities. In this contribution, we report new discovery of ca. 2.7 Ga rocks from the western Huixian in the NCC. Zircon U–Pb dating reveals their protoliths were emplaced between 2714 and 2704 Ma. The rocks are tonalitic gneisses in composition, and present similar geochemical characteristics to the Archean TTG suites and Phanerozoic high-SiO2 adakites worldwide. Zircons from the three tonalitic gneisses yield variable positive eHf(t) values of 2.3–6.7, 4.2–8.7, and 3.3–6.3, with Hf model average ages of ca. 2848 Ma, ca. 2838 Ma, and ca. 2840 Ma, respectively. The measured zircon δ18O values range from 5.5‰ to 6.2‰, 5.1 to 6.1‰, and 5.2 to 6.2‰, with weighted mean values of 5.7‰, 5.7‰, and 5.8‰, respectively, all of them overlap with the mantle range within two sigma uncertainty limits. The Hf-O isotope compositions in zircons from the tonalitic gneisses indicate that their protoliths originated in a juvenile crust-forming event at ca. 2.7 Ga. Available data suggest ca. 2.7 Ga is a major period of crustal growth in the NCC. Geochemical signatures of the ca. 2.7 Ga tonalitic gneiss reflect that their protoliths formed by partial melting of hydrated mafic rocks with variable proportions of the amphibole and garnet residues to be left behind in the residuum but absence of plagioclase and rutile in their source. The rocks are classified as HP-TTG, their protolith formed under amphibolite-facies conditions. It is noted that the ca. 2.7 Ga tonalitic gneisses in Huixian display low MgO (

中文翻译：

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华北克拉通新太古代（约2.7 Ga）地壳生长的新证据

摘要 华北克拉通 (NCC) 的主要特征是约。2.5 Ga 构造热事件，与世界上大多数其他典型克拉通明显不同。而大约 2.7 Ga 的岩石在整个克拉通中零星出露，并且仅在几个地方被发现。在这个贡献中，我们报告了 ca 的新发现。2.7 华北会县西部的 Ga 岩。锆石 U-Pb 测年显示它们的原岩位于 2714 至 2704 Ma 之间。岩石的成分为调质片麻岩，地球化学特征与世界范围内的太古代 TTG 岩层和显生宙高 SiO2 埃达克岩相似。来自三个色调片麻岩的锆石产生 2.3–6.7、4.2–8.7 和 3.3–6.3 的可变正 eHf(t) 值，Hf 模型平均年龄约为 约 2848 年 2838 马，约。分别为 2840 毫安。实测锆石δ18O值范围为5.5‰～6.2‰、5.1～6.1‰和5.2‰～6.2‰，加权平均值分别为5.7‰、5.7‰和5.8‰，均与地幔范围重叠两个西格玛不确定性极限。来自方质片麻岩的锆石中的 Hf-O 同位素组成表明，它们的原岩起源于大约 10 年的新生地壳形成事件。2.7 Ga。可用数据表明大约。2.7 Ga 是华北克拉通地壳生长的主要时期。大约的地球化学特征。2.7 Ga 调质片麻岩反映了它们的原岩是由水合基性岩部分熔融形成的，在残渣中留下不同比例的角闪石和石榴石残留物，但在其来源中没有斜长石和金红石。这些岩石被归类为 HP-TTG，它们的原岩是在角闪岩相条件下形成的。值得注意的是，ca。2.7 辉县 Ga 调质片麻岩显示出低 MgO (