How to choose a proper representation of compositional data for mineral exploration?

• Published in: Journal of geochemical exploration 2024-04, Vol.259, p.107425, Article 107425
• Main Authors: Sadeghi, Behnam, Molayemat, Hossein, Pawlowsky-Glahn, Vera
• Format: Article
• Language: English
• Subjects: Compositional data analysis; Logratio; Orogenic gold; Principal balances; Sweden; Till
• ISSN: 0375-6742; 1879-1689
• DOI: 10.1016/j.gexplo.2024.107425

Regional mineral exploration is based on geochemical data of which the nature is compositional and frequently involves a large number of components. Consequently, it mostly needs multivariate dimension reduction methods such as principal component analysis (PCA) and its various robust versions. The application of such methods, defined for real random variables, require the data to be represented in coordinates supported in the real space. However, a common problem in exploration geochemistry is to select the appropriate representation. Using centered (clr) and isometric (ilr) logratio coordinates to discriminate anomalous zones for orogeny gold exploration throughout Sweden revealed that there is, as expected, no difference between the two representation methods. The main difference affects the interpretation of the coordinates used. This is observed for regional scale exploration, while it is also needed to study different ways of representing geochemical data in local scale. [Display omitted] •Geochemical data possess a compositional nature, necessitating meaningful representation•Among compositional tools, clr and olr coordinates are used for representation•Extensive till geochemical data from across Sweden were employed for comparison•Both models exhibited strikingly similar results in terms of anomaly separation•The ilr-based model enhanced accuracy in delineating anomalous zones