Discrete Paleoproterozoic and Cretaceous mineralization events at the Liyuan gold deposit, central North China Craton

Accurate dating of Precambrian gold deposits is challenging due to the lack of suitable mineral chronometers. The North China Craton (NCC) is recognized as one of the world’s largest gold-producing regions; however, Precambrian-aged gold deposits within the NCC are relatively rare. This study aims to determine the formation age and evolutionary history of the Liyuan gold deposit (5 t Au), which is situated within high-grade metamorphic rocks of the Trans-North China Orogen. We employed U-Pb dating of hydrothermal apatite and rutile, as well as trace element analysis of texturally distinct pyrite. Two distinct stages of gold mineralization were identified. Stage I is characterized by the presence of disseminated pyrite that predominantly associated with lattice-bound gold. In contrast, stage II is marked by quartz-sulfide vein-style mineralization with visible gold and gold microinclusions within pyrite. Pyrite from Stage I (Py1) exhibits elevated As concentrations, whereas pyrite from stage II (Py2 and Py3) is distinguished by high levels of Te and Pb. Hydrothermal apatite intergrown with auriferous Py1 yielded U-Pb ages of 1895 ± 19 Ma and 1836 ± 28 Ma, which correspond to the deformation and metamorphism of the Trans-North China Orogen. The presence of positive Eu anomalies in the hydrothermal apatite suggests that it crystallized from a relatively oxidized fluid. The mechanism for the formation of hydrothermal rutile associated with the vein mineralization of stage II, is attributed to the alteration of biotite. Hydrothermal rutile was dated to 128.0 ± 6.4 Ma, which aligns with the Early Cretaceous granitic magmatism in the region. The Liyuan gold deposit was formed as a result of two distinct hydrothermal events occurring during the Paleoproterozoic and Early Cretaceous periods, respectively. This conclusion is supported by comprehensive field, textural, mineralogical, and geochronological analyses. The recently identified Paleoproterozoic orogenic gold mineralization event, which coincided with orogenic deformation and regional metamorphism during the collision between the Western and Eastern Blocks, presents new prospects for gold exploration in the well-endowed NCC. Furthermore, our study highlights the potential of apatite U-Pb dating as a reliable geochronological tool for investigating Precambrian gold deposits in other regions.