Facies architecture of an Archean komatiite-hosted Ni-sulphide ore deposit, Victor, Kambalda, Western Australia: implications for komatiite lava emplacement

Nickel sulphide mineralisation is located in structural embayments or troughs at the base of thick basal komatiite lava flows at the Victor ore body, Kambalda, Western Australia. Primary contact relations, and textural and vesicle distribution of the host komatiite lavas, particularly the development of coherent or quench fragmented margins is consistent with emplacement of komatiites under laminar flow conditions. However, the absence of sedimentary units beneath komatiites with coherent flow tops in the ore environment seems contradictory and suggests both turbulent and passive laminar emplacement, respectively. The presence of erosive basal contacts in the ore environment suggests the komatiite lava was initially turbulent and probably open channel fed. It is during this initial stage that both erosion and deposition of the NiS deposits occurred. As the flow evolved, widened and thickened, laminar flow conditions prevailed. The komatiites are inferred to have flowed in a laminar state, through the development of interior magma tubes beneath surface crusts, and to have grown endogenously.