Science News: Scientists have discovered why powerful volcanic eruptions shoot diamonds into the sky, revealing the processes behind these rare events and aiding in the identification of diamond-rich deposits.
Economic diamonds are primarily formed in Archean cratons as their thick lithospheric keels provide appropriate temperature and pressure gradients for diamond formation and stability. Upwelling beneath Archean keels (~ 200 km depth), kimberlitic magmas erupt at geologically high velocities (~ 20 m s-1 ) entrapping mantle xenoliths, including diamonds, and depositing them in surface features called kimberlite pipes. Kimberlite pipes are therefore greatly sought after, being the primary global source of economic diamonds. Through the use of tomographic models, studies have spatially correlated the global kimberlite distribution with fixed deep mantle large low-shear velocity provinces for the last 320 Ma. However, research greatly suggests these basal thermochemical structures to be mobile features, contradicting the use of tomographic models over time. Tomographic models use seismic observations to map present mantle structure, whereas flow models predict the evolution of mantle tempera