Subducting seafloor anomalies promote porphyry copper emplacement

The oceanic seafloor is scarred by fracture zones, seamounts, and large igneous provinces (LIPs) which record tectonic deformation and plume impingement through deep time. The subduction of these seafloor anomalies has been speculated to localise slab tearing, enrich the mantle wedge in volatile elements, or trigger flat slab subduction. However, the association between these subducting seafloor anomalies and the emplacement of mineral deposits in the overriding plate is poorly understood. Using a tectonic plate reconstruction of the last 170 million years paired with a machine learning model trained on the location and age of known porphyry copper deposits, we find that the subduction of seafloor anomalies is highly predictive of mineral emplacement, particularly along the American Cordillera. The subduction of fracture zones and seamounts are consistently within the top 10 highest ranked features after the crustal thickness of the overriding plate and the plate convergence velocity. We propose that fracture zones, seamounts, and LIPs have higher degrees of hydrothermal alternation and serpentinization compared to regular seafloor which oxygenates the sub-arc mantle upon their subduction, leading to more fertile conditions for porphyry copper emplacement in the overriding plate. These findings have significant implications for the discovery of new porphyry copper deposits to power the renewable energy transition.