| 华北克拉通太古宙研究若干进展 |
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| 关键词:North China Craton Archean magmatism metamorphism zircon dating Nd-Hf isotopes |
| 基金项目:中国地质调查局项目“华北克拉通太古宙早期古老陆壳物质的寻找、鉴别和研究”(编号: 1212011120151);“华北克拉通太古宙早期陆核形成与演化”(编号: 12120114021301）;“中国地质构造区划与区域地质调查综合集成”(编号: 1212010811033)和“中国及邻区海陆大地构造总体框架和演化过程及其对资源-环境的控制”(编号: 12120115070301);科技部项目“华北克拉通前寒武纪重大地质事件与成矿”(编号: 2012CB416600)和“中国标准地层建立-中国地层表的完善”(编号: 2015FY310100);国家自然科学基金项目“鲁西花岗-绿岩带的形成和演化: 地质、地球化学和锆石SHRIMP U-Pb定年”(编号: 1172127)和“冀东太古宙基底的形成和演化: 地质、地球化学和锆石SHRIMP U-Pb定年”(编号: 41472169) |
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| Some Progress in the Study of Archean Basement of the North China Craton |
| The North China Craton has experienced a long geological history which can be traced back to ca. 3.8 Ga ago. This paper reports some new progress made in recent years in the study of North China Craton in such areas as Anshan-Benxi, eastern Hebei, western Shandong, eastern Shandong and Yinshan. In Anshan, the Shengousi Complex provides evidence of magmatic events occurring at ~3770 Ma, 3660–3600 Ma, ~3450 Ma, 3330–3310 Ma, and ~3120 Ma. These data are similar to data from the Baijiafen and Dongshan complexes in showing protracted, episodic Archaean crustal evolution. In eastern Hebei, detrital and metamorphic zircons from para-amphibolite and garnet-biotite gneiss of the Caozhuang Complex gave ages of 3.8–3.4 Ga and ~2.5 Ga, respectively. Combined with previous work, the new geochronological results suggest that a significant amount of Eoarchean crustal fragments may occur in eastern Hebei and that the sedimentary protoliths of the paragneisses were deposited between 3.4 and 2.5 Ga. In western Shandong, the Archean basement can be divided into three belts: a late Neoarchean crust-derived granite belt in the northeast that consists predominantly of 2525–2490 Ma monzogranite and syenogranite and banded gneisses (Belt A), a middle to early Neoarchean belt in the center which is mainly composed of 2.75–2.60 Ga TTGs and supracrustal rocks (Belt B), and a late Neoarchean belt of juvenile rocks in the southwest that is dominated by granodiorite, gabbro, quartz diorite and tonalite, with some monzogranite and syenogranite (Belt C). Western Shandong is the only area where both early and late Neoarchean supracrustal rocks were identified. In eastern Shandong, a major magmatic event was identified at 2.9 Ga, which resulted in a major period of juvenile crustal addition from the depleted mantle. Together with 2.7 Ga rocks, the 2.9 Ga rocks underwent strong metamorphism at 2.5 Ga, probably as a result of magmatic underplating. In the Yinshan Block, there are 2.7 Ga tonalites and 2.6 Ga granites and older xenocrystic zircons in 2.5 Ga granitoid rocks. Data obtained in recent years indicate that the Yinshan Block is similar in early Precambrian geology to the Eastern Block. The authors also summarized zircon U-Pb dating and Nd-Hf isotopic features of Archean basement of the North China Craton. Combined with previous work, the authors discussed general features of the Archean crust formation and evolution of the North China Craton. It is concluded that the most important production of continental crust occurred during the late Mesoarchean to early Neoarchean period, but the most intensive and widespread tectono-thermal event took place at the end of the Neoarchean. In this new tectonic model, the authors have defined and outlined three ancient terranes (>2.6 Ga), namely Eastern Ancient Terrane, Southern Ancient Terrane and Central Ancient Terrane. |
| WAN Yu-sheng,DONG Chun-yan,XIE Hang-qiang,LIU Shou-jie,MA Ming-zhu,XIE Shi-wen,REN Peng,SUN Hui-yi,LIU Dun-yi.2015.Some Progress in the Study of Archean Basement of the North China Craton[J].Acta Geoscientica Sinica,36(6):685-700. |
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