The behaviour of low-viscous magma
This project, 'The formation, preservation and lithification of low viscosity magma pyroclasts' (PYROCLASTS), focused on magma of low viscosity. Until recently, little work had been done in this area. Such magmas typically have low viscosity. They are made of a material called kimberlite. Kimberlite pyroclastic deposits differ from other pyroclastics in three ways. They have little or no vescularity, or small, fluid-filled pouches. They tend to be spherical, and they commonly contain free crystals. PYROCLASTS investigated the behaviour of these low-viscosity magmas during explosive eruptions. Researchers also looked at how they fragment, or break up, and what processes occur during flight. Finally, they studied what influences their final structure. Research was carried out through both field and experimental studies. Researchers explored the ability of kimberlite melts to produce glassy ash. They also looked at the formation of small, solidified droplets called Pele's tears. These droplets are made of basalt. Although now completed, ongoing research related to the project is examining how volcanic liquids break up and form droplets, and the influence of viscosity and ejection velocity on this process. Some interesting information has emerged from this work. For example, researchers now know that basalt pyroclasts have smooth, shiny surfaces unbroken by vesicles. They also show a progression from irregular shapes to tears and then to spheres. Throughout this process, their size decreases. This research is important for understanding the composition of planet Earth. Knowledge of how low-viscous pyroclasts behave may help scientists predict the outcome of some volcanic explosions.
Keywords
Low-viscous magma, magma, volcanic eruption, pyroclastic deposits, lithification, low viscosity, magma pyroclasts, kimberlite, ejection velocity