Crustal Thickness Controls the Formation of Porphyry Copper Deposits: Global Correlations and Evidence from the Yidun Arc

Crustal thickness exerts a key control on the formation of porphyry Cu deposits by modulating magmatic differentiation and Cu enrichment processes. While geochemical proxies like Sr/Y ratios are established tracers of crustal thickness, their relationship with magmatic Cu content remains ambiguous. This study integrates a global geochemical compilation with a detailed case study of the Yidun Arc, eastern Tibet, to resolve this relationship. We establish a robust inverse correlation between crustal thickness and magmatic Cu content on a global scale. In the Yidun Arc, we document a pronounced north-south gradient in Cretaceous crustal thickness. This gradient directly controlled the spatial distribution of fertile, high-Sr/Y magmas, explaining the exclusive localization of Triassic and Cretaceous porphyry deposits in the thickened southern segment. Our results confirm that crustal thickness acts as a critical geodynamic filter for porphyry Cu deposit formation, providing a powerful framework for mineral exploration.