Acquisition of New Excimer Laser Ablation System for a High Resolution ICPMS Facility

The University Corporation, Northridge, Northridge CA

Investigators

Abstract

This award will support the acquisition of a new laser ablation system to be used in tandem with an existing high resolution mass spectrometer in the CSU-Northridge Department of Geological Sciences. The mass spectrometry facility at CSU-Northridge is a newly developed laboratory used primarily for analyzing isotopic ratios and the concentrations of low abundance elements in earth materials. A laser ablation system couples with the mass spectrometer and provides a way of directly sampling micrometer-scale parts of minerals and / or rocks, which is important for determining the specific timing and growth conditions of the targeted material. The laser ablation - mass spectrometry facility at CSU-Northridge is used primarily for determining ages of a variety of minerals, which has a broad range of applications across many geoscience disciplines. Some examples of those applications include: dating of igneous rocks and constraints on the timing and growth rate of continental crust; dating of metamorphism and constraints on the deformation of crust; dating of minerals in sedimentary rocks and constraints on the evolution of landscapes. Addition of the new laser supported by this award will allow the PIs to build a unique and high demand laboratory easily accessible to Los Angeles area academic institutions, many of which are minority-serving. This proposal also includes funding for a summer research initiative aimed at supporting traditionally underserved students, giving them an opportunity to receive training and mentorship using our state-of-the-art facility in a small-group setting. This support will allow the PIs to replace an aging (> 13-year old) laser ablation system with a new 193 nm ArF excimer laser ablation system. It will be coupled with an existing single collector sector field inductively coupled plasma mass spectrometer (SF-ICPMS), and used primarily for accessory mineral geochronology and in-situ trace element analysis. This new instrumentation, together with permanent, full-time technical support provided by the University, will allow the PIs to develop a regional facility that will generate precise, high-quality data with new efficiencies that allow for high sample throughput and the analysis of, for example, high n-number detrital zircon datasets. Trace element analysis, which was previously not possible because of laser signal instability, will be used on its own (rastering over glasses fused from a variety of bulk rocks), and in concert with Pb/U age data to link chemical conditions to timing of accessory mineral growth.