Mesozoic granitic rocks are widely developed in the Great Xing’an Range, and determining their emplacement age and genesis is crucial for reconstructing the tectonic-magmatic evolution of Northeast China. This paper reports the petrographic, geochronological, geochemical and zircon Hf isotopic characteristics of granites in the Huolin Gol area of the southern Great Xing’an Range to determine the formation age, source nature and geodynamic background of the rocks in this area. Zircon U–Pb dating results show that the granites in the study area were formed in the Early Cretaceous (134–130 Ma), rather than the Late Jurassic as previously thought. The granites have SiO₂ contents ranging from 75.02 to 78.53 wt.%, Na₂O = 3.55–3.89 wt.%, K₂O = 3.98–5.11 wt.%, Na₂O/K₂O = 0.72–0.97, A/CNK = 1.04–1.14. Their rare earth element (REE) distribution patterns are all right-inclined, with LREE/HREE = 3.89–12.41, (La/Yb)_N = 2.39–18.86, Eu/Eu* = 0.02–0.17. Trace element spider diagrams show significant enrichment in Rb, Th, U, K, Pb and LREEs, and depletion in Ba, Nb, Ta, Sr, P, Ti and HREEs. The zircon εHf(t) values range from +6.4 to +15.0, and the two-stage Hf model ages (T_DM2) range from 773 to 226 Ma. These characteristics indicate that the granitic rocks belong to the weakly peraluminous high-K calc-alkaline I-type granite, derived from partial melting of newly generated juvenile continental crust materials. Combined with the coeval magmatic associations, spatial distribution patterns, and regional tectonic evolution, we propose that the Early Cretaceous granitic rocks in the study area formed in an active continental margin setting, with their geodynamic mechanism linked to the subduction of the Paleo-Pacific Plate beneath the East Asian continent.

The Jiapigou mining district, a world-famous gold-producing district with a capacity that greatly exceeds 180 t Au, has a mining history longer than 200 years. The large amount of Jurassic Au mineralization in this district significantly differs from that in other districts of the North China Craton (130–115 Ma). However, the deep-seated dynamic processes and mechanisms that triggered the unique Jurassic mineralization in the Jiapigou district are poorly understood. Here, we present new data on the geology, petrography, and zircon U–Pb and Lu–Hf isotopes of the typical Huangnihe pluton in the Jiapigou district to address the above issues. The results revealed the following: (1) The Huangnihe pluton comprises mainly fine-grained granite and porphyritic granite, which were emplaced at 187 ± 2 Ma (n = 13) and 166 ± 2 Ma (n = 15), respectively. (2) The Hf isotope data indicate that the two episodes of granites exhibit distinct origins: the former (εHf(t) = −1.4 to +5.3; T_DM2 = 1784–1181 Ma) originated from juvenile lower crust, whereas the latter (εHf(t) = −14.9 to −9.7; T_DM2 = 2987–2518 Ma) was derived from Archean crust. (3) On the basis of published geochemical data, the estimated crustal thicknesses of the Jiapigou district ca. 187 Ma, ca. 175 Ma, and ca. 166 Ma ranged from 45 to 52 km, 43 km, and 58 to 63 km, respectively. Combined with regional observations, the results of this study further reveal the following: (1) The Jurassic magmatism in the Jiapigou district can be subdivided into three episodes: 187–186 Ma, ca. 175 Ma, and 166–165 Ma. (2) The crust in the Jiapigou district gradually thickened during the Jurassic and underwent partial melting during multiple episodes of Paleo-Pacific Plate subduction, thereby generating arc-like calc-alkaline (ca. 187 Ma), adakite-like (ca. 175 Ma), and adakite magmas (ca. 166 Ma) that were emplaced to form corresponding granitoids. Moreover, syn-ore magma mixing between the ca. 175 Ma adakite-like felsic magma and mantle-derived mafic magmas was considered a crucial process in magma evolution. This process in turn promoted the enrichment of ore-forming elements within the magma system, which significantly contributed to the formation of the large Au mineralization in the Jiapigou district.