华北克拉通南缘鲁山太古宙基底的形成和演化

Archean crustal formation and evolution of the Lushan area in the southern margin of the North China Craton

鲁山地区保存和出露很好的太古宙基底岩石。文章报道了2件魏庄片麻岩的原岩年龄分别为（2867±5）Ma和（2768±5）Ma，变质作用时代分别为（2775±6）Ma和（2775±56）Ma。结合已发表数据，魏庄片麻岩原岩形成时代可大致分为2867~2928Ma和2765~2768Ma两个阶段；榆树庄片麻岩原岩形成于2829~2897Ma、2752~2778Ma和2723Ma；斜长角闪岩原岩形成于2838~2845Ma、2747~2794Ma和2730Ma。尽管三者岩性上存在差异，但原岩形成的期次和时代相当，指示它们在成因上可能存在联系。鲁山多地陆续发现2.8~2.9Ga的岩石，表明该地区存在一定规模的中太古代基底。通过与胶东、霍邱等地对比，笔者认为华北克拉通南缘可能存在中太古代的古老陆块，其重要的初生地壳生长事件发生在2.9~3.0Ga。

Archean basement rocks are well preserved in the Lushan area. In this study, zircon SHRIMP U-Pb dating results suggestthat two samples, collected from the Weizhuang gneiss in Lushan, record magmatic age of 2867±5 Ma and 2768±5 Ma, respectively.They underwent metamorphism at 2775±6 Ma and 2775±56 Ma, respectively. Together with data available, the protoliths of theWeizhuang Gneiss formed at two stages, i.e., 2867-2928 Ma and 2765-2768 Ma, while protoliths of the Yushuzhuang Gneiss andamphibolite formed at three stages (2829-2897 Ma, 2752-2778 Ma and 2723 Ma versus 2838-2845 Ma, 2747-2794 Ma and 2730Ma). Although the three types of rocks are different in lithology, they record similar magmatism phases, indicating the existence ofgenetic connections among them. Recently, 2.8- 2.9 Ga rocks were identified in many areas, indicating the existence ofMesoarchean basement on a certain scale in Lushan. Compared with the Precambrian evolution of Jiaodong and Huoqiu, it isconcluded that a Mesoarchean block, which underwent a significant crustal growth event at 2.9-3.0 Ga, may be present along the southern margin of the North China Craton.