Professor John Maclennan
John has been an Official Fellow since 2005, and is one of our Directors of Studies in Natural Sciences (Physical). He is Professor of Igneous Petrology at the Department of Earth Sciences, and their Academic Champion for Careers.
Biography
Originally from Glasgow, John studied as an undergraduate at Emmanuel, on the Natural Sciences course. He specialised in Physics, Mathematics and Geology, helped by the fact that the Department of Earth Sciences is opposite Emmanuel's Front Court! His postdoctoral placements included an EU Marie Curie Individual Fellowship at the Institut de Physique du Globe de Paris and a NERC Postdoctoral Fellowship at the University of Edinburgh.
He has held visiting positions at the Institute for Study of the Earth’s Interior, Misasa, Japan; the Institut de Physique du Globe de Paris; the University of Iceland and as an Adjunct Scientist at Woods Hole Oceanographic Institution, Massachusetts. He has been a University Lecturer and Reader at Cambridge, and has been the Professor of Igneous Petrology since 2020. He has also received the President’s Award and Bigsby Medal of the Geological Society of London.
Teaching
John supervises our undergraduates in Earth Sciences. He presents the flagship introduction to Earth Sciences lectures in first year Natural Sciences as well as papers in Mantle Melting (Third Year) and Crustal Magmatic Processes (Fourth Year). He leads field trips to Skye, Spain and Iceland for undergraduate and postgraduate teaching. He supervises MSci and PhD students with a focus on Volcanic and Magmatic Processes. In 2014, he received the Pilkington Prize for excellence in teaching.
Research
John uses the chemistry of volcanic rocks to understand the physics of magma generation, transport, storage and eruption. He combines fieldwork with leading-edge microanalysis and computational techniques to provide a quantitative understanding of magmatic processes. His work has focused on the behaviour of Icelandic volcanoes, providing a platform for a global view of magmatism at spreading ridges, ocean islands and large igneous provinces. He is striving to use the erupted products of enormous historical eruptions to improve our ability to identify the likely precursory signals for future damaging volcanic events. John researches diffusion chronometry of magmatic processes to track pre-eruptive magma ascent and storage timescales, and looks at petrological records of magma storage and transport including melt inclusions, volatiles and thermobarometry. He also focuses on constraining budgets and understanding volcanism as an environmental agent through carbon and other volatiles in the Earth's mantle, and forcing and feedbacks between magmatism, mantle melting and climate change.
He has also been involved in submersible studies of undersea volcanoes in the Pacific, and investigations of modern and ancient volcanoes in a number of locations including Hawai’i, the Galápagos, Reunion, Scotland, Oman, Italy, Libya and the Moon.