Mafic ultramafic intrusive rock sample locations were selected from the GSWA geochemistry database (WACHEM) and classified using whole rock geochemistry and a discriminant plot for cumulate rocks (Barnes, 2023)

Example of how the cumulate classification layer derived from whole-rock geochemical data in the Geochemistry–mafic ultramafic intrusion layer can be used in the exploration of intrusion-hosted magmatic Ni-Cu-Co deposits (Barnes, 2023):

a) Schematic illustration, showing two stages in the development of an intrusion-hosted Ni–Cu–Co sulfide system from Barnes (2023). In this model, most (but not all) ore-hosting intrusions contain ultramafic cumulates.

b) Discriminant plot for ultramafic (UM) and mafic cumulates and non-cumulate mafic rocks (Barnes, 2023), using  Al2O3 wt% versus Mg number (M#, molar percent MgO/[MgO + FeO]) data from the Geochemistry–mafic–ultramafic intrusion layer

Diagram templates and additional references are available in CSIRO Magmatic Sulfide Systems: https://research.csiro.au/magnico/workshops-and-resources/

Geochemistry—mafic–ultramafic intrusion

Barnes, SJ 2023, Lithogeochemistry in exploration for intrusion-hosted magmatic Ni–Cu–Co deposits: Geochemistry: Exploration, Environment, Analysis, v. 23, no. 1, article no. geochem2022-025, doi:10.1144/geochem2022-025.