Paleomagnetism is the study of the Earth’s ancient magnetic field, which can be recovered from remanent magnetizations preserved in rocks. Such work is essential for understanding the history of the magnetic field, but also for reconstructing the past motions of the tectonic plates (because magnetic records can be used to determine ancient latitudes).
However, ancient magnetic records can become contaminated by younger magnetic signals, and so several paleomagnetic procedures have been designed to magnetically “clean” paleomagnetic rock samples. Standard paleomagnetic cleaning approaches heat the rock samples or subject them to alternating magnetic fields, but some rocks do not respond well to these treatments, and so they tend to be avoided and unstudied. Some of these unstudied rocks are likely to carry highly precious magnetic records that could solve outstanding Earth science problems, but their secrets remain hidden away.
In this project, we will investigate why the conventional paleomagnetic cleaning approaches fail on some rocks but also explore another under-utilized paleomagnetic cleaning approach that involves the selective destruction of magnetic grains through dissolution via acid.
The ultimate aim of this work will be to recover paleomagnetic signals from Ediacaran rocks in northern Norway, which are essential to resolving an important global tectonic problem from this time (when the continents appear to have been moving unrealistically fast), but which have so far proven challenging to resolve with the conventional approaches. But the results of this work will also have broader implications for paleomagnetism and our ability to unravel the history of the ancient magnetic field.
Work in this project will involve fieldwork to northern Norway (to collect paleomagnetic samples), the execution of chemical and paleomagnetic experiments, and microscopy.
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