Assoc Prof. Andy Tomkins - Honours Projects

Determining the age of undated impact structures in Australia

Supervisors: Andy Tomkins
Field of study: Planetary Science
Preferred Program: Honours

There are five meteorite impact craters in Australia that are undated but could plausibly have been generated in the mid-Ordovician period. The mid-Ordovician was a time characterised by unusually high meteorite impact rates, a unique period in at least the last 550 million years and probably much more. This project will visit one or more of these five Australian impact craters to collect samples for geochronology. The samples will be characterised prior to mineral separation work and then geochronology will be conducted on mineral separates. This work will help determine whether Australia bears several scars from the Ordovician impact spike (one is known already).

Platinum group minerals in 3.8 billion year old chromitite from Greenland

Supervisors:  Andy Tomkins, Rachel Kirby
Field of study:  Early Earth Petrology/Geochemistry/Geochronology
Preferred Program: Honours

We have some samples from Greenland of the world’s oldest known chromitites. These form by fractionation of chromite from an ultramafic magma chamber in the lower crust. We have done synchrotron work already to locate numerous small platinum group minerals (PGMs) amongst the chromite grains. This project will follow-up on that initial work to characterise the mineralogy of the PGMs, and then attempt to conduct laser ablation geochronology on selected grains. The aim is to explore whether PGMs in rocks like this can be used to date mantle processes, or perhaps even processes associated with accretion of the Earth.

For further information, contact Andy Tomkins