2D elemental mapping of micrometeorites via LA-ICP-ToF-MS

Micrometeorites, tiny extraterrestrial particles, largely produced by collisions of celestial bodies, which survived atmospheric entry, fall on Earth at a rate of 40000 tons annually, and can be retrieved on the Antarctic. Micrometeorites represent a valuable source of information on the chemical evolution of the Solar System. Their microscopic size (50-2000 mm) warrants the use of novel in situ mapping techniques of elemental analysis. Hyphenated with a low-dispersion laser ablation (LA) system, ICP-ToF-MS allows for 2D mapping at several hundred hertz, with each laser shot recorded as a single pixel, and for quasi-simultaneous rapid acquisition of almost the entire periodic table.

In this contribution we present approaches for and results of high-resolution multi-element 2D mapping of micrometeorites cross-sections via LA-ICP-ToF-MS. Quantitative data for each pixel was obtained through a combination of multi-point calibration - via a set of natural glass reference materials - and 100% oxide normalization to account for ablation yield. variations. Detection limits down to a few ng/g were attained while only using a 5x5 µm square laser spot. Analysis of the elemental images of micrometeorites allows to recognize and isolate melts of different composition, complimenting petrographic observations.