Ore deposits formed in the Critical Zone: Laterite Ni, Co, REE, Nb and supergene Cu

Critical Zone processes can mobilize metals from bedrock, or pre-existing ore bodies, to form regolith-hosted (laterites) and supergene deposits of copper, nickel, cobalt, rare earth elements and niobium. Other critical elements such as the platinum group elements and scandium are also an exploration target. Many deposits form under particular climatic and geomorphic conditions in the Cenozoic from coupled physical-chemical-biological processes, however, older examples can be preserved in the rock record. This chapter focusses on economic ore deposits that are formed in the Critical Zone, and specifically, two distinct types of deposits that originate from contrasting parent rocks in diverse tectonic, climatic, biological, and hydrological environments: laterite (Ni, Co, REE, Nb) and supergene (Cu) deposits. We present an overview on a suite of currently economic laterite deposits worldwide, and then we focus on supergene Cu deposits in the Andean Cordillera of South America as a key locality to understand supergene Cu upgrading. These systems exemplify two endmembers that illustrate the range of processes that can lead to metal enrichment in the Earth's surface, and offer the opportunity to assess the nature of element cycles and the effects of changing climate on interactions in the Critical Zone.