Investigation of a new palaeothermometer: High precision isotope ratio measurement of multi-substituted isotopic molecules in carbonates

We intend to develop a newly viable and potentially very powerful technique for measuring the temperature at which many different calcium carbonate deposits, such as stalagmites, tufas, mollusc shells and corals, have been formed at various times over the past few hundred thousand years. Potentially this will provide a vast amount of information about the nature of climate change on a global scale and over long time periods. Importantly, many of these types of geological deposits can be very precisely dated by measuring the small amounts of uranium and thorium they contain, and because very small samples (about a milligram) can be used for temperature measurements, it should be possible to obtain temperature records with very high time resolution (probably decadal or less). To achieve the goal we shall use a custom built mass spectrometer, an instrument that is capable of measuring very small differences in the masses of calcium carbonate molecules within the rocks. This is a technically challenging project that will require a lot of experimentation and calibration before it can be used routinely and it is these technical aspects that are the focus of this project. When perfected, this technique will probably have many other geological, mineralogical and hydrothermal applications in addition to investigating past climates.