Postcumulus processes recorded in whole-rock geochemistry – [publication]

According to the ‘trapped liquid’ paradigm, whole-rock chemical compositions of cumulate rocks in layered intrusions can be represented as closed-system multicomponent mixtures of the cumulus phases and the liquids from which they crystallised. Alternative open-system models for cumulate solidification assert that intercumulus liquid is continuously mobile as a result of compaction of crystal mushes. In the closed-system models, all excluded elements, i.e. those incompatible in the cumulus phases, should be correlated with one another, whereas in open systems the more incompatible elements should be decoupled from the more compatible ones and correlations should be poor. These alternative hypotheses are tested using a database of >63 000 whole-rock analyses of mostly ultramafic cumulates from a single package of layers across the entire width of the Mirabela layered intrusion.

Barnes, S. J., and Williams, M. J., 2024, Postcumulus processes recorded in whole-rock geochemistry: a case study from the Mirabela layered intrusion, Brazil: Journal of Petrology, v. 65, doi: 10.1093/petrology/egae019