MASS SPECTROMETRY AND GEOLOGIC AGE MEASUREMENTS IN INTEGRATED STEM INSTRUCTION

Understanding assumptions inherent to radiometric age determinations, and sources of uncertainty in geologic ages, provides a fundamental foundation for comprehending time scales and rates of processes in topics ranging from the origin of our solar system, plate tectonics, evolutionary biology, and global climate change. Mass spectrometry provides robust age determinations by constraining critical parent-daughter isotopic ratios and data to evaluate inheritance and closed system behavior. To encourage student's critical evaluation of radiometric ages they should be introduced to the basic principles of mass spectrometry. Auburn University made a substantial commitment to integrating mass spectrometry research and geochronology with instruction by supporting development of the Auburn Noble Isotope Mass Analysis Laboratory (ANIMAL). The ANIMAL facility is based upon a novel 10 cm radius, 90°-sector mass spectrometer with double-focusing geometry and a high-sensitivity Nier-type source for the analysis of single-crystal scale (laser) samples using an electron multiplier. This spectrometer was built at Auburn University with direct participation of it's students and faculty in the departments of geology, chemistry, physics, and also mechanical and electrical engineering. Students in our core science elective classes (enrollment ~100) are captivated by the integration of science, technology, engineering and mathematics (STEM) inherent to building and testing a mass spectrometer and collecting radiometric age data. Our plans for ANIMAL in the immediate future include web-based instrument control so that undergraduate students in such core classes may undertake laboratory study in the context of a collaborative project. Students would then be responsible for collating and analyzing the project data to evaluate the roles of precision and accuracy in age determinations, and gauge the appropriateness of assumptions regarding inheritance, closed-system behavior, and simultaneous crystal growth.