A note on the IUGS reclassification of the high-Mg and picritic volcanic rocks

Abstract

The purpose of this short note is to offer some comments and observations on the new IUGS classification of high-Mg rocks (Le Bas, 2000), particularly its use of the terms 'komatiite' and 'picrite' with no reference to texture or the original usage of these terms. At the outset of this discussion we would like to place on record that we are in agreement with the need to redefine the nomenclature of high-Mg rocks. There are, however, important issues relating to both the use of the term 'komatiite' for all extrusive volcanic rocks with >18 wt % MgO and the definition and use of the term 'picrite', neither of which are discussed by Le Bas (2000).