GSA MINERALOGY GEOCHEMISTRY, PETROLOGY, AND VOLCANOLOGY DIVISION EARLY CAREER AWARD: APPLICATION OF SINGLE SHOT LASER ABLATION SPLIT STREAM TO ACCESSORY PHASE PETROCHRONOLOGY

This contribution details the Single Shot Laser Ablation Split Stream (SS-LASS) method, a novel analytical approach that involves splitting the aerosol generated from single pulses of a 193nm excimer laser and sending a portion to two inductively coupled plasma mass spectrometers, thereby enabling simultaneous acquisition of U-Th/Pb isotopic dates and trace element concentrations/ratios from the same volume of ablated material. Synthetic data and empirical constraints are utilized to optimize data acquisition parameters for both isotopic ratios and elemental data, suggesting that an instrument duty cycle of <300ms is required to adequately characterize the full transient signal and thereby minimize data inaccuracy. The utility of the LASS technique to the solid earth sciences, and in particular petrochronology, is demonstrated with examples that highlight: 1) the accuracy of both isotopic (2 – 4% 2 SD) and trace element concentration (~5% 2 SD) data obtained by this method; 2) the ability to rapidly obtain large-n datasets, particularly useful in detrital geochronology / geochemistry studies as well as for the identification of geologically important but volumetrically minor components in volcanic and sedimentary rocks that can then be targeted for subsequent high precision analysis; 3) generation of one-dimensional ‘depth’ profiles to assess timing and duration of (re)-crystallization event(s) preserved in thin rim domains, as well as assess the length scales of major- and trace-element diffusion in accessory phase minerals; and 4) production of two- and three-dimensional isotopic and elemental distribution maps that provide high spatial resolution information and enable statistical interrogation of the relationship between date and trace element abundances / ratios at the sub-crystal scale.