Recent publications show that molar-ratio diagrams preserve absolute compositional variations of certain mafic igneous rock assemblages, while traditional Harker diagrams for all igneous rocks obfuscate relationships. For some Australian granitoid suites, molar-ratio diagrams illustrate chemical variations accurately and permit quantitative objective testing of petrogenetic models (e.g., restite model) with observed chemical compositional data.
- Received May 19, 1995.
- Accepted June 20, 1995.
- © Geological Society of London 1996