What is the geochemical classification of basalt?

Traditionally, geochemical classification of basaltic rocks of unknown tectonic affinity has been performed by discrimination dia- grams. Although easy to use, this method is fairly inaccurate because it only uses bi- or trivariate data. read more

Each type of basalt has unique geochemical signatures that can then be used to correlate to ancient basalts to infer their tectonic setting. A lot has been published on the geochemical signature of basalts, but a good introductory petrology book would cover the majority of the important findings. read more

revisions to the geochemical classification of granites Fe-index: the boundary between ferroan and magnesian rocks The FeO/(FeO + MgO) ratio of rocks is an important indication of the fractionation history of a suite of rocks. read more

The first of the modern geochemical schemes for classification of granitic rocks was introduced in an abstract by Chappell & White in 1974. They recognized two distinct granitoid types in the Lachlan Fold Belt of eastern Australia. read more