Diamonds in ophiolites: recycling deep mantle into supra-subduction zones

In the early days of plate tectonic theory Australian geochemist Ted Ringwood introduced his ‘megalith’ model1 proposing that diamonds form when organic carbon in sediments overlying oceanic crust is subducted 400-650 km deep into the mantle transition zone. He sought to explain diamonds that are later incorporated into kimberlite intrusions in cratonic areas. Surprising new discoveries of diamonds and high-pressure minerals within oceanic rocks (ophiolites), where their mineralogy is profoundly anomalous, are unexplained and represent the greatest challenge to interpretation of such rocks since suggestions that they form in plates overriding subduction zones.

Funding: UQ Earmarked Scholarship Scheme

Advisory Team: Professor Jonathan Aitchison, Dr Renjie Zhou