Implementation of a noble gas spectrometric platform

点击翻译按钮获取中文摘要

GEOTOP is the only research center in Canada having a scientific renowned expertise in noble gas geochemistry, here intended in a broader sense and not limited to geochronology (e.g., K-Ar dating). Noble gases (He, Ne, Ar, Kr and Xe) are inert and rare elements, whose isotopic and elemental composition cannot be altered by any chemical reaction. Consequently, their isotopic composition records the sources of gases and the geological processes which partitioned them in the terrestrial reservoirs. Their use as geochemical tracers is powerful, as illustrated by the scientific discoveries of profound and fundamental nature that were done in the last half-century, including the discovery of pre-Solar grains in meteorites, the extinct radionuclides, the origin of Earth's and Mars' atmospheres, mantle degassing, or the dating of glaciated surfaces by cosmogenic noble gas nuclides. The Noble Gas Laboratory at GEOTOP is deeply involved in numerous research programs aimed to discover the origin, evolution and residence time of geological fluids in the continental crust, from local groundwater to geothermal brines. The results of these studies have numerous applications to better understand the origin of energy and ore deposits, a vital economic sector for Canada. The laboratory has initiated an ambitious research program on the origin of major elements on Earth, mainly carbon and halogens (Cl and Br) and their cycling in the Earth System, using noble gases as reference tracers. This scientific endeavor is alimented by studies of hydrothermal fluids in Mexico, Iceland, Chile and France and in diamonds, as precipitation products of fluids in the mantle. Noble gas geochemistry requires a state-of-the-art analytical platform, which is composed of three elements, each one vital to the success of these time-consuming but highly rewarding analyses: 1) extraction systems of gases from geological materials (vacuum crushing for fluid inclusions, high-temperature furnaces for diamonds, vacuum extractors for fluids); 2) a purification line, which is vital to obtain a mixture of pure noble gases without spurious gas that can create interferences and thus dramatically compromise the analyses; and 3) a state-of-the-art high-sensitivity, high-resolution noble gas mass spectrometer (NGMS). The Noble Gas Laboratory at GEOTOP owns the high-end HELIX-MC NGMS, which guarantees high-precision analyses of noble gases, and numerous extraction systems acquired over the years with NSERC RTI and CFI grants. However, the purification line, acquired 14 years ago with my first NSERC RTI grant, is at the end of its life cycle creating a serious analytical bottleneck, dramatically endangering HQP training and progress in their research. This application is to update the noble gas analytical platform by acquiring a new, fully-automated purification line to guarantee the future studies of the numerous graduate students and collaborators at GEOTOP and from abroad.