Geology seminar series talk by Nadine Cooper (University of Otago)

Earth’s lithospheric mantle is heterogenous in age, composition and rheology. Refractory mantle lithospheres are those that have experienced high levels of melt extraction, resulting in depletion in major and trace elements. These are commonly recognised from Archean cratons, where the cool and buoyant residues underpin and support the longevity of these areas. However, there are increasing occurrences of refractory mantle being documented in post-Archean environments.

My thesis examines the evolution of some of these refractory mantle lithospheres, from New Zealand, South America and South Africa, with the goal of addressing whether these are relicts of Archean lithospheres or formed in modern tectonic settings.

Results indicate that refractory mantle xenolith suites can form in different modes, with some being Archean and overprinted in the Phanerozoic (South Africa), others being Proterozoic in age (South America) and others forming via subduction zones in the modern Earth (New Zealand).