Magmatic erosion of high-temperature-melting cumulates in the Bushveld Complex by chemical dissolution

The Bushveld Complex in South Africa shows spectacular examples of regional and local magmatic erosion the floor cumulates by new melt batches that replenished evolving magma chamber. Field observations indicate that, at some stratigraphic levels, least, 15–20 m pre-existing cumulates, often nearly monomineralic composition (e.g., anorthosite or orthopyroxenite) were completely removed on a scale. What was major agent this – (partial) melting dissolution remains poorly understood. Thermal appears to be poor candidate because normal basaltic melts (∼1220–1260°C) cannot heat up their temperature (∼1400–1500°C). We explored, therefore, possibility these high-temperature-melting slightly superheated (15°C above liquidus) basaltic-andesitic recharged chamber spread out laterally along its as basal flows. This done using freely available thermodynamic tool for phase equilibria modeling open systems Magma Chamber Simulator. Our can digest 4.5–8.0 wt% bulk without inducing crystallization melts, despite them being much colder than liquidus temperatures cumulates. is equivalent 15–24 given layer about 350 thick. conclude has been mostly controlled chemical replenishing melts.