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Paleomagnetism facilities in the Department of Geology

The motivation behind the Otago Paleomagnetic Research facility

Global earth and climate systems have recently dominated national and international forums. They are beginning to impact on the way we live, and we need to understand how they work. New Zealand's unique geological evolution offers important insight into these natural earth and climate systems, providing some of the most significant archives - both long and short-term.
The challenge facing geologists is to interpret these records in a time scale that means something to us - and to work out which intervals of the archive are most relevant to the specific problems we face.

Equipment in the facility

Cryogenic magnetometer in the Department of Geology Cryogenic magnetometer in the Department of Geology

The focus of the facility is a state of the art - cryogenic (or supercooled) magnetometer - one of the most sensitive magnetometers in the world. It is housed in a 30 cubic metre magnetically shielded room - the first of its type in the southern hemisphere - and was designed and constructed in house at the University of Otago.

Two tonnes of high silicone transformer steel have been hung in two independent shields on a non-magnetic frame and the resulting internal field is 150 nannotesla - less than 0.25% of Earth's surrounding magnetic field. In other words, the earth's magnetism does not interfere with the magnetism of rock and sediment samples being analysed.

The cryogenic magnetometer is what we call a "long core system" - it enables 1.5 metre long sediment cores to be measured, as well as the individual paleomagnetic samples making it ideal for marine, lake and land-based work.

Kappa Bridge in the Department of Geology Kappa Bridge in the Department of Geology

The cryogenic magnetometer also has "in-line" AF demagnetisation, magnetic susceptibility and anhysteretic remanent magnetism capabilities. The lab also houses a Molspin spinner magnetometer, an ASC Thermal demagnetiser, and ASC impulse magnetiser and a Bartington single sample susceptibility bridge. Both magnetometers are networked into a central computer server tat provides common access for different computer platforms and data analysis packages.

The laboratory also has a collection of field sampling equipment and shields.

The construction of the facility was funded by grants from the University of Otago Research Equipment Committee and the Institute of Geological and Nuclear Sciences (http://www.gns.cri.nz). The Foundation for Research, Science and Technology (FRST) and Antarctica New Zealand have provided grants to undertake various programmes of research involving palaeomagnetism at Otago.