Determining the age and petrogenesis of the Mesozoic magmatic rocks may provide crucial evidence regarding the tectonic setting and evolution of the North China Craton (NCC). In this paper, we present new zircon U–Pb ages and geochemical data for bimodal volcanic rocks from Zhuozi area in the eastern Yinshan belt, NCC, to discuss their petrogenesis and tectonic implications. The volcanic rock suite consists of basalts, rhyolites, and trachytes. According to the results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), the rhyolitic and trachytic rocks have zircon U–Pb ages of 136.9 ± 0.8 Ma and 134.0 ± 1.7 Ma, respectively, representing their eruption ages. The basalts are enriched in large-ion lithophile elements (LILE; Ba, Rb, Sr, and Th) and light rare-earth elements (LREE), and are relatively depleted in high field strength elements (HFSE; Nb, Ta, and Ti). In addition, the basalts are characterized by high fractionations of rare-earth elements (REE), with (La/Yb)_N = 24.87–42.85. These features suggest that they were derived from low-degree partial melting of enriched lithospheric mantle metasomatized by subduction-related components. The rhyolitic rocks have low mean Al₂O₃ (12.26 wt%) and TiO₂ (0.14 wt%) contents and Mg# (14.92) values, with relatively low total REE abundances. They have high alkali and Zr, Ce, Y, and Nb contents and high Ga/Al ratios, with notably positive Pb and negative Sr, Ba, and Eu anomalies observed in the primitive mantle-normalized trace element diagram. These features indicate that the rocks exhibit characteristics of A₁-type granite and likely derived from the partial melting of a crustal source. The trachytic rocks are show moderate trace elements and SiO₂, MgO, Fe₂O₃^T, and TiO₂ contents. They were possibly generated by fractional crystallization of the underplating basaltic magmas and assimilated minor crustal materials. The geochemical characteristics, in combination with the regional geology, suggest that the bimodal volcanic rocks formed in an intraplate extensional setting likely associated with the retreat of the subducted Paleo-Pacific plate.

确定中生代岩浆岩的年龄和成岩作用可能为有关华北克拉通（NCC）的构造环境和演化提供重要证据。在本文中，我们提供了新的锆石U–Pb年龄和来自NCC东部印山带卓兹地区的双峰火山岩的地球化学数据，以讨论其成因和构造意义。火山岩套件包括玄武岩，流纹岩和小摆线。根据激光烧蚀-电感耦合等离子体质谱法（LA-ICP-MS）的结果，流纹岩和疏松岩的锆石U-Pb年龄分别为136.9±0.8 Ma和134.0±1.7 Ma，分别代表它们的喷发年龄。玄武岩富含大离子的亲石元素（LILE； Ba，Rb，Sr和Th）和轻稀土元素（LREE），并且相对缺乏高场强元素（HFSE； Nb，Ta和Ti）。此外，玄武岩的特征是稀土元素（REE）的高分馏，其中（La / Yb）_N  = 24.87–42.85。这些特征表明它们源自俯冲相关成分交代的富集岩石圈地幔的低度部分熔融。流纹岩的平均Al ₂ O ₃（12.26 wt％）和TiO ₂（0.14 wt％）含量和Mg＃（14.92）值均较低，总REE丰度相对较低。它们具有较高的碱和Zr，Ce，Y和Nb含量，且具有较高的Ga / Al比，在原始地幔归一化痕量元素图中观察到的Pb异常明显，而Sr，Ba和Eu异常明显。这些特征表明岩石具有A _1特征型花岗岩，可能源自地壳部分融化。滑行岩中的微量元素和SiO ₂，MgO，Fe ₂ O ₃ ^T和TiO ₂含量适中。它们可能是由基底玄武岩浆和同化的次要地壳物质的分步结晶产生的。地球化学特征与区域地质特征相结合，表明在板内伸展环境中形成的双峰火山岩可能与俯冲古太平洋板块的退缩有关。