2012-09-18 – Seminar: John Brodholt
18 September 2012 – Seminar
When: 4pm on Tuesday, 18 September 2012
Where: DIAS, Geophysics Section, 5 Merrion Square, Dublin 2, (library)
Speaker: Prof. John Brodholt (UCL)
Title: D” – Between a Rock and a Core
Between the Earth’s mantle and core is a region known as D’’. We have known about D’’ since the 1950s and it exhibits many interesting and varied seismic properties. In 2004 a phase transition from the lower mantle phase perovskite to a new post-perovksite phase of (Mg,Fe)SiO3 was discovered to occur at around the pressure conditions of D’’. Much of what we see in D’’ now seems to be explained by this phase transition. In a 2005 Nature editorial I was quoted as saying “Is that it?”. Is D’’ really just yet another mantle phase transition? Since then there have been over 500 papers on post-perovskite, on its properties, and how it affects the dynamics and behaviour of the Earth as whole. So is that it? Is D’’ just a phase transition, and if so, how does it affect how the Earth works? This talk will present an overview of D”, our experimental and theoretical results on the properties of the post-perovskite phase, and some ideas on how our view on the Earth is changing as we understand more about D”.