Tectono‑magmatic control on the intensity of decratonic gold mineralization in the southeastern margin of the North China Craton: A perspective from geochemical comparison

Abstract

ABSTRACT The North China Craton (NCC), notably the southeastern margin of the NCC, hosts the most typical example of decratonic gold deposits. However, the factors controlling the intensity of decratonic gold mineralization and the relation between the geodynamic model of decratonization and gold mineralization still deserve to be well elucidated. The Bengbu and the Jiaobei uplifts are located at the southeastern margin of the NCC and the two uplifts have similar tectonic positions and metamorphic basements, yet the intensity of gold mineralization is quite distinct. Mesozoic mineralization and magmatism in both uplifts are controlled by the same deep geodynamic process. Accordingly, in this review, we make an effort to find solutions to these problems by integrating the whole-rock geochemical and Sr-Nd-Pb isotopic data as well as zircon U-Pb-Hf-O isotopic data from late Mesozoic magmatic rocks from the Bengbu uplift and the Jiaobei uplift. The late Mesozoic magmatism of the two uplifts can be divided into three stages, i.e. Late Jurassic (stage I), middle Early Cretaceous (stage II), and late Early Cretaceous (stage III). Comparative studies of the gold-related rocks in these two areas indicate that the intensity of the decratonic gold mineralization is controlled by magmatic source composition (i.e. the affinity of the upper crust of the South China Block), intrinsic magmatic variables of gold-related rocks (i.e. redox state and volatiles content), as well as lithospheric architecture (i.e. lithospheric thickness). Additionally, the integrated data of magmatic rocks in the three stages suggest that plate subduction acts as the recycling engine factory responsible for the decratonic mineral systems. In the early stage (Triassic), continental subduction of the South China Block induced pre-enrichment of ore-forming nutriments in magma sources, whereas in the late stage (Early Cretaceous), oceanic subduction of the paleo-Pacific plate led to the craton destruction, thereby triggering related magmatism and gold mineralization in the eastern NCC.