Carbonated magmatic sulfide systems: Still or sparkling?

Abstract

For decades, there has been debate surrounding the transport of dense metal-rich sulfide liquid in mafic magmas. This topic is crucial to understanding the genesis of valuable resources of nickel, copper, and platinum-group elements, which are essential for a sustainable, emission-free energy future. Recent studies of mineralized mafic magmas suggested that gas bubbles adhere to sulfide globules, reducing their density and favoring upward transport. While this hypothesis may explain sulfide mobility in near-surface magmatic environments, it is at odds with key mineralogic and textural observations and does not explain how long-distance sulfide transport operates. Here, we suggest an alternative hypothesis that builds on previous observations, focusing on the interaction between carbonate melt and sulfide liquid. We demonstrate experimentally that carbonate melt wraps sulfide globules forming a relatively mobile pair that may mediate metal-rich sulfide transport from mantle to crust.