The southwestern extension of the Jiao-Liao-Ji belt in the North China Craton: Geochronological and geochemical evidence from the Wuhe Group in the Bengbu area
The southwestern extension of the Jiao-Liao-Ji belt in the North China Craton: Geochronological and geochemical evidence from the Wuhe Group in the Bengbu area
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DOI：
10.1016/j.lithos.2018.01.021
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发表时间：
2018-04
期刊：
影响因子：
3.5
通讯作者：
Chaohui Liu;Guochun Zhao;Fulai Liu;Jia Cai
中科院分区：
文献类型：
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作者：
Chaohui Liu;Guochun Zhao;Fulai Liu;Jia Cai
五河杂岩位于华北克拉通东南缘。该杂岩体由变质古元古代钾质花岗岩和表壳岩组成，其中表壳岩包括凤阳群和五河群。下五河群变镁铁质岩，火成锆石U-Pb年龄为2126±37Ma，εHf(t)值为-6.22～+8.38，异晶锆石年龄为2.39～2.36Ga、2.55～2.54Ga、2.77～2.69Ga。两组。第 1 族岛弧拉斑玄武岩显示出平坦至略微右倾的稀土元素模式以及中度负 Nb、Ta、Zr 和 Ti 异常。第 2 组成熟弧钙碱性玄武岩表现出强烈分异的球粒陨石归一化 REE 模式和明显的负 Nb、Ta 和 Ti 异常。这些变镁铁质岩石是由弧下贫化地幔楔部分熔融形成的，这些地幔楔经过活动大陆边缘板片衍生的熔体的改造。根据最年轻的碎屑锆石和后期侵入体的年龄，可以将该群的沉积年龄限制在2.16~2.10Ga时期。碎屑锆石U-Pb年龄主要年龄峰为2.69Ga和2.52Ga，次峰为2.88Ga、2.78Ga、2.35Ga和2.17Ga，大部分来自五河杂岩和胶东地体晚中太古代至早古元古代花岗岩。与石榴石角闪岩或麻粒岩共存的大理岩中的变质锆石以单晶或围绕岩浆锆石核的过度生长（或重结晶）边缘的形式出现，屈服年龄为1882±19Ma至1844±15Ma。可比较的约。 2.1Ga钾质花岗岩，具有A型花岗岩亲和性，约。具有弧状地球化学特征的2.1Ga变基性岩、2.1~1.9Ga变沉积单元以及1.9~1.8Ga俯冲和碰撞相关的麻粒岩相变质作用表明五河杂岩与焦辽吉带具有相同的古元古代晚期构造演化过程，前者是后者的西南延伸。
The Wuhe complex is located at the southeastern margin of the North China Craton. The complex consists of metamorphosed Paleoproterozoic potassic granitoids and supracrustal rocks, of which the latter include the Fengyang and Wuhe groups. Meta-mafic rocks from the lower Wuhe Group have igneous zircon U-Pb ages of 2126 ± 37 Ma withεHf(t) values of −6.22 to +8.38, and xenocrystic zircons of 2.39–2.36 Ga, 2.55–2.54 Ga and 2.77–2.69 Ga. Geochemically, the meta-mafic rocks can be classified into two groups. Group 1 island arc tholeiites display flat to slightly right declined REE patterns and moderately negative Nb, Ta, Zr, and Ti anomalies. Group 2 mature arc calcalkaline basalts display strongly fractionated chondrite-normalized REE patterns and evidently negative Nb, Ta and Ti anomalies. These meta-mafic rocks formed by partial melting of sub-arc depleted mantle wedge which had been modified by slab-derived melts at an active continental margin. Depositional age of the group can be constrained in the period of 2.16–2.10 Ga based on ages of the youngest detrital zircons and latter intrusions. U-Pb ages of detrital zircons yield major age peaks of 2.69 Ga and 2.52 Ga, with minor peaks at 2.88 Ga, 2.78 Ga, 2.35 Ga and 2.17 Ga, most of which are derived from the late Mesoarchean to early Paleoproterozoic granitoids in the Wuhe complex and the Jiaodong Terrane. Metamorphic zircons in the marbles coexisting with garnet amphibolites or granulites occur as either single grains or overgrowth (or recrystallization) rims surrounding magmatic zircon cores and yield ages of 1882 ± 19 Ma to 1844 ± 15 Ma. The comparable ca. 2.1 Ga potassic granites with A-type granite affinity, the ca. 2.1 Ga meta-mafic rocks with arc-like geochemical features, the 2.1–1.9 Ga meta-sedimentary units and the 1.9–1.8 Ga subduction- and collision-related granulite-facies metamorphism suggest that the Wuhe complex and the Jiao-Liao-Ji Belt share the same late Paleoproterozoic tectonic evolution process and the former is the southwestern extension of the latter.