High Temperature Isotope Geochemistry LaboratoryAntonio Simonetti

RESEARCH

Theme 1: Nuclear Forensics – Developing Spatially Resolved Chemical and Isotopic Capabilities for Source Attribution: Traditionally, nuclear forensics analyses for pre- and post-detonation material, as well as natural radioactive materials, have focused on time-consuming approaches (i.e., weeks) for detailed chemical and isotopic analysis of specimens of interest. These include sample dissolution and subsequent column extractions to concentrate radionuclides, or neutron activation analyses that require irradiation in a reactor. These methods provide highly precise and accurate results, with very low detection limits. However, the inherent chemical and isotopic signatures at high spatial resolution are compromised. Although it is possible to conduct analysis of specific portions of samples, the traditional "bulk" methods do not support rapid analysis with spatial resolution. However, my research group has recently published several studies in nuclear forensics analysis that focus on spatially resolved signatures. State-of-the-art instrumentation such as the latest generation NuPlasmaII LA-MC-ICP-MS instrument available in MITERAC has been successfully applied to the nuclear forensics field. It is therefore possible to conduct rapid and spatially resolved (at the level of microns or less) analyses that are sufficiently accurate and precise for source attribution, especially when combined with other microanalytical methods. An invited chapter contribution to the recently held Mineralogical Association of Canada sponsored short course entitled, "Uranium – Cradle to Grave" in Winnipeg, Manitoba (May 2013), contains a summary of the trinitite-related nuclear forensics work conducted by my group between July 2011 and March 2013.

Theme 2: Chemical and Isotopic Investigation of Alkaline Complexes: The chemical and isotopic nature of the subcontinental mantle is examined through the isotopic and chemical investigations of alkaline igneous rocks, such as carbonatites, nephelinites, and kimberlites. Carbonatites are igneous rocks consisting of >50% magmatic carbonate minerals, and occur on all continents (including Antarctic) and range in age from Archean to present-day. On the basis of experimental data and compilation of their stable (carbon and oxygen), noble gas (Ne, Xe, Kr, He, Ar), and radiogenic (Nd, Sr, Pb) isotope data, carbonatite melts are clearly derived from Earth's upper mantle. Despite the small number of occurrences worldwide (n=527) compared to their basaltic counterparts, carbonatites continue to receive considerable deserved attention because of their unique enrichment (relative to crustal abundances) in incompatible trace elements, including the rare earth elements (REEs). These elements are of strategic importance in the continually burgeoning fields of superconductors, electronics and computing. Given their unique geochemical signatures derived from upper mantle sources, widespread tectonic and geographic distribution, and emplacement ages that span >3.0 billion years of Earth's history, these features render carbonatites as insightful probes into deciphering the chemical nature, temporal evolution, and metasomatism of Earth's upper mantle. Several of my PhD students are conducting detailed research work on carbonatite complexes world-wide, either at high spatial resolution for deciphering the chemical and isotopic make-up of individual minerals using LA-(MC)-ICP-MS instrumentation within MITERAC, or solution mode analysis for bulk samples.

Theme 3:Analytical Methods Development: My research group's ICP-MS-based research interests and publications are varied and these cover many disciplines within the Earth Sciences, and also include recent collaborations outside of Geology, such as with anthropologists and medical doctors. In recent years, I've also been involved with the development of innovative laser ablation-ICP-MS techniques, such as chapter contributions in the Mineralogical Association of Canada-sponsored short courses entitled, "Laser-Ablation-ICPMS in the Earth Sciences", held at the annual GAC-MAC Meeting in St. John's, Newfoundland in 2001, and the "Laser Ablation ICP-MS in the Earth Sciences: Current Practices and Outstanding Issues", held at the 2008 V.M. Goldschmidt Conference in Vancouver, Canada.