The Wuhe complex (WC), exposed at the southeastern margin of the North China Craton (NCC), is an important constituent of the Eastern Block of the NCC. In order to better understand the Precambrian crustal composition and evolution of this region, a comprehensive investigation on zircon geochronology and Hf isotopes, as well as whole-rock geochemistry and Sr-Nd-Pb isotopes was conducted on alkaline ultrapotassic granitic gneisses from the WC at Mashan. These gneisses are considered as meta-igneous rocks based on geochemical and mineralogical criteria (with special reference to zircon cathodoluminescence images). They are characterized by modally abundant alkali feldspar (more than 60%) and quartz (more than 30%) while plagioclase is rare. Mafic minerals are sodic amphiboles such as arfvedsonite and eckermannite, aegirine and rare biotite. Minor constituents are rutile, muscovite, apatite and barite. Major elements geochemistry shows high SiO₂ (69.85%–74.51%) and K₂O + Na₂O (9.67%–12.17%) contents, high K₂O/Na₂O (7.41–22.53) ratios, and relatively low MgO (0.37%–0.87%) and CaO (0.10%–0.23%) contents. Trace elements geochemistry shows significant depletions of Nb, Y, Ce, Ga, and REE (rare earth elements) relative to anorogenic granites. These features suggest that the magmatic protoliths of the studied gneisses belong to ultrapotassic silica-saturated alkaline series from an extensional background, perhaps in a subduction-related rifting environment. As concerning isotope geochemistry, their ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios are 16.6297–17.1877, 15.4454–15.5066, and 36.6036–38.0304, respectively, and ε_Nd(t) values vary from −1.7 to +9.1. Two samples yielded zircon ²⁰⁷Pb/²⁰⁶Pb ages of 2615 ± 4 Ma and 2617 ± 5 Ma, respectively, representing their precursor ages. The zircon igneous core domains exhibit oscillatory growth zoning with positive ε_Hf (t) values (+2.5 − +6.6). These data, coupled with chondrite-normalized and primitive-mantle-normalized element patterns, suggest that the precursors of the studied granitic gneisses were mainly derived from a subduction-modified ultrapotassic syenitic parental magma, and may be considered as a particular group of A-type granites, involved in an important crustal growth and reworking event at ~2.6 Ga. These rocks experienced a granulite-facies metamorphic stage accompanied by partial melting, as testified by clinopyroxene + rutile + K-feldspar + spinel + quartz + apatite inclusions in zircon metamorphic domains which were dated at ~2.5 Ga. The occurrence of this metamorphic stage is also supported by the lower ΣREE contents, negative Eu anomalies, and high Ti-in-zircon temperatures (>800 °C) of metamorphic zircon mantles dated at ~2.5 Ga. Eventually, the studied rocks suffered a later ~1.85 Ga metamorphic overprinting, possibly related to the Paleoproterozoic collisional orogeny recorded in the region.

出露在华北克拉通东南缘的五河杂岩体是华北克拉通东部地块的重要组成部分。为更好地了解该地区前寒武纪地壳的组成和演化，对 WC 的碱性超钾质花岗片麻岩进行了锆石年代学和 Hf 同位素以及全岩地球化学和 Sr-Nd-Pb 同位素的综合研究。马山。根据地球化学和矿物学标准（特别参考锆石阴极发光图像），这些片麻岩被认为是变质火成岩。它们的特点是具有丰富的碱性长石（超过 60%）和石英（超过 30%），而斜长石很少见。镁铁质矿物是钠闪石，如阿弗维森石和埃克曼石、绿闪石和稀有黑云母。次要成分是金红石、白云母、磷灰石和重晶石。主要元素地球化学显示高SiO₂ (69.85%–74.51%) 和 K ₂ O + Na ₂ O (9.67%–12.17%) 含量，高 K ₂ O/Na ₂ O (7.41–22.53) 比率，以及相对较低的 MgO (0.37%–0.87%) ) 和 CaO (0.10%–0.23%) 含量。微量元素地球化学显示，相对于非造山花岗岩，Nb、Y、Ce、Ga 和 REE（稀土元素）显着耗尽。这些特征表明，所研究的片麻岩的岩浆原岩属于来自伸展背景的超钾硅饱和碱性系列，可能处于与俯冲相关的裂谷环境中。至于同位素地球化学，它们的²⁰⁶ Pb/ ²⁰⁴ Pb、²⁰⁷ Pb/ ²⁰⁴ Pb 和²⁰⁸ Pb/²⁰⁴ Pb 比率分别为 16.6297–17.1877、15.4454–15.5066 和 36.6036–38.0304，并且 ε _Nd (t) 值从 -1.7 到 +9.1 不等。两个样品产生的锆石²⁰⁷ Pb/ ²⁰⁶ Pb 年龄分别为 2615 ± 4 Ma 和 2617 ± 5 Ma，代表了它们的前体年龄。锆石火成岩核心域表现出具有正 ε _{Hf 的}振荡生长区带(t) 值 (+2.5 − +6.6)。这些数据，加上球粒陨石归一化和原始地幔归一化的元素模式，表明所研究的花岗片麻岩的前体主要来自俯冲改性的超钾正长岩母岩浆，可以被认为是一个特殊的 A-型花岗岩，参与了~2.6 Ga 的重要地壳生长和改造事件。这些岩石经历了麻粒岩相变质阶段，伴随着部分熔融，如斜辉石 + 金红石 + 钾长石 + 尖晶石 + 石英 + 锆石中的磷灰石包裹体所证明的那样年代为~2.5 Ga 的变质域。这一变质阶段的发生也得到了年代为~的变质锆石地幔较低的ΣREE 含量、负Eu 异常和高Ti-in-zircon 温度（>800 °C）的支持。 2.5 加仑。