Stephen Sparks: Large silicic magma bodies and very large magnitude explosive eruptions скачать в хорошем качестве

Stephen Sparks: Large silicic magma bodies and very large magnitude explosive eruptions

An enduring and fascinating problem is how to generate very large silicic magma bodies capable of feeding eruptions of hundreds or thousands of km3 of magma in the form of ignimbrite and tephra fall with associated caldera formation. A conceptual model is developed based on geological, geophysical and petrological evidence, and framed by physical models of fluxing magmas through the crust. Primitive basaltic magmas flux into the base of the crust where they stall, cool and crystallize, create mushy hot zones containing residual differentiated mafic to intermediate melts. These melts separate, ascend and accumulate at higher levels (broadly the middle crust) where the same process is repeated to generate mushy, hot-zone silicic melts through a combination of fractional crystallization, reactive flow and crustal assimilation. Petrological evidence for very rapid accumulation of shallow silicic magma bodies favours transport of silicic magma from the middle crust through dykes. Rapid magma transport enables fluxes that are orders of magnitude higher than time-averaged silicic melt generation in middle crustal mush. Sir Robert Stephen John Sparks, CBE, FRS is Emeritus Professor at the School of Earth Sciences at the University of Bristol. He is one of the world's leading volcanologists and has been widely recognised for his work in this field. Steve's research concerns quantitative studies of geological processes using a combination of field studies, laboratory experiments, analytical studies and theoretical modelling. His main focus has been on volcanic and igneous processes and he has also made contributions in fundamental fluid mechanics, sedimentology, and risk assessment methodologies for natural hazards. Steve Sparks has published over 300 papers, which have been cited more than 10,000 times, and is an ISI Highly Cited Researcher. He has a distinguished record of service to the geological community: He was President of the Geological Society of London from 1994 to 1996, President of IAVCEI from 1999 to 2003, and President-elect of the VGP section of the American Geophysical Union for 2009. More information at: https://www.bristol.ac.uk/people/pers... https://en.wikipedia.org/wiki/Robert_...