Structural relationships between Neoarchean granite and its host rocks in the Zanhuang Massif: Implications for tectonic evolution of the North China Craton

The early Precambrian tectonic evolution of the North China Craton has been debated for years. Here, we focus on the structural relationships between the ca. 2.5 Ga Wangjiazhuang granite and its host rocks in the Zanhuang Massif by integrating multiscale observations and methods, including field studies, electron backscatter diffraction fabric analysis, and host‑rock geochronology, to evaluate the tectonic evolution of the Zanhuang Massif and its relationship to the North China Craton. At the pluton scale, foliations in both the marginal Wangjiazhuang granite and its host rocks are parallel to the boundary of the pluton. However, the internal foliation of the Wangjiazhuang granite strikes nearly east−west, approximately parallel to the regional foliation in the host rocks. At the outcrop scale, the host rocks near the granite are characterized by a shear sense of downward transport attributed to the emplacement of the granite, whereas those farther away exhibit a regional top-to-the-southeast shear sense. At the grain scale, the Wangjiazhuang granite exhibits both magmatic and subsolidus fabrics that are mutually parallel. Electron backscatter diffraction analysis shows that quartz in the Wangjiazhuang granite mainly underwent prism <a> slip deformation corresponding to 500−600 °C, and plagioclase also experienced deformation at >550 °C, consistent with the medium- to high-temperature subsolidus deformation. The subsolidus fabric at the margin of the granite is more developed than at the core, while the magmatic fabric shows the opposite pattern. These relationships indicate that the granite foliation is partially coupled with the main foliation in the host rocks. The Wangjiazhuang granite is identified as a syn-tectonic intrusion. The structures at the margin of the Wangjiazhuang granite and its nearby host rocks were mainly controlled by the emplacement of the granite, while the internal fabrics of the granite were influenced by regional tectonic convergence. Maximum depositional ages obtained from zircon U-Pb dating of the host rocks, including quartzite and quartz-mica schist, are 2.53−2.52 Ga. Structural relationships between the Wangjiazhuang granite and its host rocks constrain the depositional age of the host rocks to between 2.53 Ga and 2.50 Ga. Structural and geochronological analyses of the Wangjiazhuang granite and its host rocks indicate that the Zanhuang Massif experienced northwest−southeast convergence at ca. 2.50 Ga, following the arc−continent collision between the Fuping terrane and the Eastern Block. Critically, second-order extension was potentially driven by slab rollback or break-off, facilitating the emplacement of syn-tectonic A-type granite. This study demonstrates the operation of a dynamic plate tectonic regime involving subduction, collision, and slab failure in the late Neoarchean North China Craton.