Rock Deformation – SOP
This is the latest version of the Rock Deformation Lab standard procedures. This document is a work in progress and is updated frequently.
Experimental Geochemistry – SOP
This is the latest version of the Experimental Geochemistry Lab standard procedures. This document is a work in progress and is updated frequently.
LIME: Log-ratio Inversion of Mixed End-members
LIME is a suite of MATLAB scripts to calculate phase abundances in natural rocks and experimental samples. In the study of igneous and metamorphic rocks, mineral abundances are used to classify rock types, characterize volcanic processes, and define chemical reactions. Common approaches for calculating phase abundances, such as multiple linear regression, suffer from mathematical artifacts that can lead to inaccurate assumptions. Compositions are reported as percentages with sums mathematically constrained to 100%. This fixed sum constraint may lead to erroneous coefficients when determining chemical reactions (e.g., a mineral being on the wrong side of the chemical reaction). Additionally, mineral abundances are often reported without any estimate of uncertainty. This is problematic when those values are used in subsequent calculations to define trends without statistical significance. LIME algorithm improves upon previous methods by constraining phase proportions to positive values and providing realistic estimates for uncertainty on each phase abundance. LIME can be found on GitHub, and the associated manuscript is published in Geochemistry, Geophysics, Geosystems.