Hunter π in the Sci – ‘Palaeomagnetism lies at the “core” of plate tectonics and marine geoscience.’

Join us for a discussion with special guest speaker:  Bob Musgrove. Bob is a geoscientist who’ll talk about  how ‘Palaeomagnetism lies at the “core” of plate tectonics and marine geoscience.’

All are welcome to attend the meeting. No need to register, just come along.

Agenda:

4:55pm – STEM current situation

5:00pm – Introduction

5:10pm – From spinning electrons to twisting bacteria to twirling continents: how palaeomagnetism lies at the “core” of plate tectonics and marine geoscience.

5:50pm – Questions and discussion. 6:25pm – Wrap up session

6:30pm – Close.

About Bob Musgrave:

Bob Musgrave’s peripatetic career in geophysics took him from palaeomagnetic studies of plate motion in the Solomon Islands, Vanuatu and New Zealand, to studies of solid methane ice (“gas hydrate”), and the bacteria that “eat’ it, in cores of deep marine sediments with the International Ocean Drilling Program, to a decade or more of teaching geophysics and geology at La Trobe University, and finally to 16 years of puzzling over the geology of eastern Australia with the Geological Survey of NSW. Now in post- redundancy semi-retirement, he continues to operate a palaeomagnetic laboratory at the University of Newcastle, when he is not being called back to do urgent contract work for the people who thought him redundant, but now seem to miss his talents

Bob graduated with his PhD in geology and geophysics from the University of Sydney in 1987. His PhD, and postdoctoral research at Victoria University of Wellington, the Australian National University, and the University of Tasmania, applied palaeomagnetism to the tectonics of the southwest Pacific.

Abstract

Ferromagnetism is a coincidental, but very useful, consequence of electron “half-integer spin” and quantum mechanics. Ferromagnetic minerals in rocks can preserve a permanent magnetisation (a “remanence”). Magnetite, a ferromagnetic iron oxide, is nearly ubiquitous in rocks, and its deposition – either through cooling of a magma to form an igneous rock, or settling as a pre-existing grain in sediments – allows those rocks to preserve a magnetic record of the direction of the Earth’s field relative to the rock at the time the rock was formed, which (if we’re lucky) does not change if the rock subsequently moves. It’s this property which is the basis of the branch of geophysics called palaeomagnetism. Early research in palaeomagnetism was key to the acceptance of the once-controversial hypotheses of continental drift and sea-floor spreading, the key concepts behind the theory of plate tectonics. The “compass” provided by palaeomagnetism continues to be useful in contemporary studies of tectonics, providing our best measure of the rotation of chains of volcanic islands and the bending of mountain belts. But long before humanity had discovered a use for either compasses or geophysics, bacteria had cracked the secret to using Earth’s magnetic field to steer by. Indeed, bacteria play a role in preserving – and destroying – the palaeomagnetic record that we have only recently come to understand.