Public Lecture by Chris Hawkesworth (expired event)

The Onset of Plate Tectonics on Earth.

The Earth is the only known planet on which there is plate tectonics, and on which there is life as we know it. It was not always that way, the Earth initially had a magma ocean, it cooled through a stagnant lid phase, and at some stage plate tectonics became the dominant tectonic regime. There are many models of the conditions required to initiate plate tectonics, but the evidence of when it started has to come from the geological record. Western Australia contains some of the best preserved rocks from the period over 3 billion years ago when dramatic changes in tectonic regime took place.

This lecture discusses the nature of the geological record, it explores links between different tectonic styles and the chemistry of the igneous rocks, and changes in the rigidity of the continental crust that might be associated with the development of plates. It explores changes that reflect the onset of plate tectonics that can be recognised from the rocks and minerals that have survived to the present day, and considers possible links between the development of plate tectonics and life on Earth.

Chris Hawkesworth is a geologist who applies isotopic systems to unravelling how and when the continental crust was generated and the links between geochemistry and tectonics. He is interested in constraining rates of natural processes from the geological record, and placing regional studies in a global context. In recent years he has used the mineral zircon as an archive of the evolution of the continental crust, and investigated how its composition has changed from the Hadean to the present. Chris is a graduate of Trinity College Dublin, and obtained his D.Phil at Oxford working with Ron Oxburgh in the Tauern Window of the Eastern Alps. He set up an isotope research group at the Open University before moving to Bristol in 2000. He served as Deputy Principal at the University of St Andrews from 2009 to 2014, and he is an elected Fellow of a number of societies including the Royal Society and the Royal Society of Edinburgh. He holds Emeritus positions at the Universities of Bristol and St Andrews.