Mineralization and prospecting method of the komatiite-related nickel deposits in the Yilgarn craton, Australia

The Kalgoorlie terrane of the Yilgarn craton in West Australia is a unique area in the world where Ni sulfides deposits in Archean komatiites are extremely abundant. Komatiite-hosted Ni sulfide deposits in the Kalgoorlie terrane have been classified into two types: ①deposits consisting of high-grade massive and matrix or net-textured ores on the bottom of komatiite lava flows composed of volcanic peridotites, represented by the Kambalda deposit; ②disseminated nickel sulfides within central zones of thick dunitic bodies, represented by the Mt. Keith deposit. The fertile komatiitic sequences are generally late Archean (2.70Ga) in age, have dominantly Al-undepleted (Al2O3/TiO2=15~25) chemical affinities, and often occur with sulfur-bearing country rocks in dynamic high-magma-flux environments, such as compound sheet flows with internal pathways facies (Kambalda-type) or dunitic compound sheet flow facies (Mt Keith-type). The nickel sulfide deposits were formed in dynamic lava channels or magma conduits by sulfur-undersaturated mafic-ultramafic magmas through magmatic processes (crystallization, differentiation and concentration) and assimilation of crustal sulfur. Based on the discussion on the genesis of the ore deposit, the authors put forward the prospecting criteria and exploration methods for this type of ore deposits.