Lithospheric architecture and evolution of the Qinling Orogen of Central China and associated controls on metallogeny

Abstract

Orogenic events are not only of importance for the geological evolution of regions and continents but are also significant controls on the formation timing, genesis, and nature of the mineral deposits hosted by the resulting orogen. This study highlights the use of multi-proxy elemental and isotopic mapping of granitoids to advance our understanding of lithospheric architecture and the formation of large-scale mineral systems associated with orogenic events. Here, we combine and review regional multi-proxy element–isotope systematics and the spatial and temporal relationships between granitic magmatism and mineral deposit formation within the Qinling Orogen of Central China. The collation of these data allows the modeling of the evolution of Triassic lithospheric architecture of the orogen and its controls on metallogenesis in this region. The Qinling Orogen is divided into eastern, middle, and western segments by two north-south trending lithospheric discontinuities located at 103°E–104°E and 107°E–108°E. Spatial variations in the Nb–Ta–Zr–Hf elemental and Sr–Nd–Hf isotopic compositions of Triassic granitoids throughout this region provide insight into the heterogeneity of mantle and crust material within this region, as well as the interaction between crust and mantle derived melts within the Qinling Orogen. The orogenic Au and porphyry Cu and/or Mo mineralization within this region is also concentrated along lithospheric discontinuities. These include granitoid-hosted porphyry Cu deposits that cluster and are localized within older crustal material with the most enriched Sr–Nd–Hf isotopic compositions and low Nb/Ta ratios, suggesting the crucial role of fertile metasomatic lithospheric mantle in the formation of these porphyry Cu systems. In comparison, porphyry Mo/Mo–Cu deposits are generally located in areas with younger basement material that has been reworked multiple times, suggesting that intense crust–mantle interaction promotes the reworking of ancient crustal material, which mobilized Mo within the older crustal material to be incorporated into porphyry Mo systems. The links between tectonism, orogenic processes, and metallogeny within the Qinling Orogen outlined in this review not only provide insights for future exploration within this region but also in other orogenic systems globally, highlighting the importance of incorporating orogenic and tectonic processes in mineral systems and exploration targeting.