This award will permit the acquisition of a 213 nm laser, which will be coupled to an existing inductively coupled plasma mass spectrometer (ICPMS) to enable laser ablation mass spectrometry (LA-ICPMS) at Middlebury College. LA-ICPMS is a rapidly growing field which has been transformative because it allows rapid analysis of very small regions (~10 microns) on materials such as minerals, shells, and artifacts. At Middlebury College, the LA-ICPMS will be housed in the Geology Department and will be used primarily to undertake uranium (U) - lead (Pb) dating and trace element analyses of minerals, which are the primary recorder of past tectonics. We also anticipate usage by biologists and by archaeologists who are interested in understanding the source materials and trade patterns of ancient tools. The proposal was widely supported by faculty at nearby colleges and will be primarily dedicated to undergraduate research, providing hands-on research experience for students regardless of the scope or budget of their project. Users will include a diversity of students, including many underrepresented groups and first time college students.
Acquiring a laser will allow numerous projects to be undertaken in more efficient and effective ways. For example, laser ablation radically expands the number of possible ICPMS applications, including the ability to analyze materials in-situ with high spatial resolution, which is essential for many applications. It also reduces sample preparation time and complexity relative to solution chemistry, facilitating a wider user base for the existing ICPMS. One internal project will use the provenance of detrital minerals in offshore sediment cores to test predictions of dynamic uplift in the eastern U.S. Another will use detrital zircons in Paleozoic meta-sedimentary rocks to test longstanding models of Appalachian tectonics. A third internal project will use the laser to better understand the origin of U and Th in bedrock aquifers with unsafe alpha activity. External users have also put forward a range of project ideas. Many users are interested in U-Pb geochronology to date igneous rocks, establish the timing of regional metamorphic events, and reconstruct cratonic evolution using detrital zircons. Other users are interested in measuring trace elements to establish the provenance of archaeological artifacts, understand petrogenesis of young magmatic centers, and undertake trace element thermo-barometry.
