This Instrumentation and Facilities Program grant supports establishment of an automated noble gas extraction and purification system to be coupled to an existing noble gas mass spectrometer at the Berkeley Geochronology Center (BGC). This system will be optimized for noble gas analyses relevant to quantitative surface process studies, primarily measurements of cosmic-ray-produced helium and neon as well as supporting noble gas diffusion studies. The extraction system will include automation hardware and software, a high vacuum chamber for automated laser extractions, calibrated standard pipettes, a gas purification system, a cryogenic system to separate noble gases from one another, and diode laser optics. The system will take full advantage of the relative speed and simplicity of cosmogenic noble gas measurements as compared to other cosmogenic-nuclides. This will allow us to address problems in Earth surface dynamics requiring large numbers of cosmogenic-nuclide measurements, including the study of stochastic processes and the need to sample across gradients in a large array of parameters which may control the rates of surface processes.
The existing and planned collaborations between the PIs and other researchers engaged in quantitative surface process research ensure that the proposed facility will be useful and accessible to a large cross-section of the Earth science community. Increased availability of cosmogenic noble gas measurements will lead to progress in Earth surface process studies, including quantitative geomorphology, landscape evolution, and Quaternary geochronology. A wide array of researchers spanning the field of Earth surface process research, as well as BGC?s record in making state-of-the-art analytical facilities available to a broad range of U.S. and international researchers, including numerous early-career scientists, postdoctoral researchers, and graduate students, ensures that the proposed facility will benefit the Earth science research community as a whole.
This grant funded construction of a system for extracting and analysing noble gases such as helium, neon, and argon that naturally occur in rocks and minerals. The actual system has three components: first, a device for extracting trace gases from mineral samples by heating them under vacuum; second, a similar device for extracting these gases by crushing, rather than heating, the samples; third, a system for separating the gases of interest from contaminants and purifying them for analysis. This system is unusual in that it is optimized for extracting and analysing trace amounts of rare isotopes of helium and neon produced by cosmic-ray bombardment of surface rocks. These "cosmogenic" isotopes are important in Earth science because they are only produced at the Earth's surface -- the cosmic-ray flux responsible for their production cannot penetrate deeply into rock or soil. Thus, measurements of cosmogenic helium and neon can be used to determine how long rocks or minerals have resided at the Earth's surface, which in turn is useful in determining the age of earthquakes, fault movement, glacier advance and retreat, or other geologic events that create or modify surfaces. Construction of this system, therefore, increases the capacity of the U.S. Earth science community to study these types of events, thus facilitating research and understanding in areas that include, for example, erosion and sediment transport processes, earthquake hazard analysis, and glacier change.
