Determining temperature of precipitation for carbonate minerals is of high scientific and practical value. If one is capable of determining at what temperature the carbonate shell of a marine organism precipitated, one can reconstruct the temperature of the ocean at the time the organism lived. This opens up the possibility of investigating the state of past climates on Earth. Similarly, if one can determine at what temperature a diagenetic mineral formed, one can predict the conditions under which this mineral was precipitated, and hence constrain the environment of diagenesis with greater accuracy. This is of high value for an industry application as it offers greater predictability of subsurface reservoirs.
Traditional methods of determining temperature of precipitation all have strength and weaknesses. Fluid inclusions allow the determination of the temperature of precipitation, the composition of the fluid, and pressure. However, fluid inclusions are not always present or large enough, the determination of temperature come with a large error range, and the inclusion might not be primary. Traditional stable isotope of oxygen can be applied to any carbonate mineral and are fast, but the signal is a composite of both temperature and the isotopic composition of the fluid: One must guess the isotopic composition of the fluid in order to determine temperature.
This project is a lab-based project aimed at developing and calibrating a novel isotopic technique: clumped isotopes. The clumping of heavy isotopes in the lattice of carbonate minerals has been shown to be dependant only on temperature as this effect is driven by thermodynamics only. Hence, clumped isotopes offer a perfect paleothermometer, but the measurement is very challenging. We took a two-pronged approach to clumped isotopes: Dr. Anne-Lise Jourdan is the principal investigator on the project based on a manual extraction line for clumped isotopes, while Dr. Simon Davisworks at producing an automated line for clumped isotopes. Dr. Cédric John oversees both projects and provides the application to diagenesis.