Comment on 'Mexican peridotite xenoliths and tectonic terranes: Correlations among vent locations, texture, temperature, pressure, and oxygen fugacity' by J. F. Luhr & J.J. Aranda-Gomez (1997)

Abstract

This comment addresses the interpretation of oxygen fugacity data for spinel peridotile xenoliths from five Mexican volcanic fields presented by Luhr & Aranda-Gomez (Journal of Petrology, 38, 1075-1112, 1997). The postulated east-west increase of the ΔFMQ ('relative oxygen fugacity', where FMQ is fayalite-magnetite-quartz) values is inherent to the method and therefore of questionable geological significance. Increases in ΔFMQ do not necessarily mirror oxidation processes in the mantle controlled by subduction-related fluids.