Continuous online D/H measurements of hydrous minerals

The ratio of the heavy to light hydrogen isotopes (D/H) is used to understand the history of planetary atmospheres and the role of water in the formation of surface materials.  For example, D/H measurements of clay minerals on Mars can be used to understand the hydrological setting at the time of formation. This IRAD proposes to develop a system to measure the D/H isotope ratio of hydrous minerals. The ratio of the heavy to light hydrogen isotopes (D/H) is used to understand the history of planetary atmospheres and the role of water in the formation of surface materials.  For example, D/H measurements of clay minerals on Mars can be used to understand the hydrological setting at the time of formation. This IRAD proposes to develop a system to measure the D/H isotope ratio of hydrous minerals.

The goal of this project is to develop a system to measure the D/H ratio of hydrous phases of planetary analog samples and martian (SNC) meteorites.  To do this, we will couple a state-of-the art Commercial Water Isotope Analyzer (for D/H and ¹⁸O/¹⁶O of water, here after presented in del notation as δD and δ¹⁸O) with a custom front end to thermally evolve water from samples under a carrier gas stream.  The front end will be capable of stepped heating, in which water evolved at different temperatures is collected and then injected in bulk to the analyzer, and continuous heating, in which the δD of water is analyzed continuously as it is evolved from a sample. 

Stepped heating is a conventional method used to study the isotopic composition of volatiles in meteorites because the mass spectrometer must receive discrete pulse of gas, as isotope ratios are measured by integrating the areas under peaks of different masses of interest.  Optical isotope analyzers, only recently commercially available, can continuously measure high precision isotope ratios of trace amounts of water, which could enable continuous δD measurement of waters thermally evolved from samples.  This may be advantageous over batch methods, especially for samples that have multiple mineral phases releasing waters with different isotopic compositions over a narrow temperature range.