What is this layer?
Ratios of Ni/Ti for ultramafic rocks, derived from the GSWA geochemistry database. Ni/Ti ratios can be used to interpret the volcanic environment in which a system formed as stated by Le Vaillant et al. (2016): ‘Ni/Ti ratios correlate with the original olivine content of the rock, constraining the silicate nickel background and highlighting subtle sulfide-related nickel enrichments.’
Legend
|
Legend |
Range |
Classification |
Description |
Reference |
|---|---|---|---|---|
|
Ni/Ti SOURCE |
0–1 |
Manual |
Values between 0 and 1 represent less prospective rocks, likely to be komatiite basalts or spinifex-textured komatiites (from Le Vaillant et al., 2016). The applied ranges of ratio values are based on Figure 1c |
|
|
1–100 |
Manual |
Ni/Ti values between 1 and 100 represent more prospective rocks, likely to be cumulate-textured komatiites (from Le Vaillant et al., 2016). The applied ranges of ratio values are based on Figure 1c |
||
|
>100 |
Manual |
Ni/Ti values between 100 and 1500 likely represent sulfide-bearing cumulates (from Le Vaillant et al., 2016). The applied ranges of ratio values are based on Figure 1c |
a) Schematic illustration of a regional komatiite flow field, modified from Hill et al. (1995)
b) Comparison of Ni/Ti and Ni/Cr ratios between fresh bedrock and top of fresh rock saprolite in the Agnew area in Western Australia, data compiled by Barnes et al. (2014)
c) Plot shows the potential use of pXRF in evaluating the prospectivity of a komatiite unit using Ni/Ti and Ni/Cr ratios, modified from Le Vaillant et al. (2014)
References
Barnes, SJ, Fisher, LA, Anand, R and Uemoto, T 2014, Mapping bedrock lithologies through in situ regolith using retained element ratios: A case study from the Agnew-Lawlers area, Western Australia: Australian Journal of Earth Sciences, v. 61, p. 269–285.
Barnes, SJ, Hill, RET, Perring, CS and Dowling, SE 2004, Lithogeochemical exploration of komatiite-associated Ni-sulfide deposits: Strategies and limitations: Mineralogy and Petrology, v. 82, p. 259–293.
Hill, RET, Barnes, SJ, Gole, MJ and Dowling, SJ 1995, The volcanology of komatiites as deduced from field relationships in the Norseman-Wiluna greenstone belt, Western Australia: Lithos, v. 34, p. 159–188.
Le Vaillant, M, Barnes, SJ, Fisher, L, Fiorentini, ML and Caruso, S 2014, Use and calibration of portable X-Ray fluorescence analysers: Application to lithogeochemical exploration for komatiite-hosted nickel sulphide deposits: Geochemistry: Exploration, Environment, Analysis, v. 14, p. 199–209.
Le Vaillant, M, Fiorentini, ML and Barnes, SJ 2016, Review of lithogeochemical exploration tools for komatiite-hosted Ni-Cu-(PGE) deposits: Journal of Geochemical Exploration, v. 168, p. 1–19.