A pXRF analysis and Comparison of Palagonite from Iceland’s Western Volcanic Zone with Implications for Identifying Glaciovolcanism on Mars

Session: 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

Presenting Author:

Authors:

Abstract:

Evidence for volcano-ice interactions on Mars is found in geomorphological features such as tuyas, cones, and tindars. On Earth, glaciovolcanism is a widespread process in ice-covered regions like Iceland, Antarctica, and Canada. Potential analagous glaciovolcanic products on Earth and Mars include palagonite, an alteration product of mafic lavas. This work aims to characterize the chemical “fingerprint” of palagonite, in all its phases, using techniques applicable by the Mars Rovers, such as portable X-ray fluorescence spectrometry (pXRF).

We examined a glaciovolcanic sample with visible palagonitization from Bræðravirki Ridge, Western Volcanic Zone, Iceland. This sample was orange-yellow in color with grain sizes varying from lapilli to ash. We acquired major and trace element concentrations on a Vanta Max V2MR pXRF. Tests were conducted on in situ rough surfaces, cut surfaces, and powders that were sieved (<45 microns) and prepared in a plastic XRF sample cup between polypropylene thin-film. Additionally, the BHVO-2 and BCR-2 USGS standard powders were measured.

We found that all analyses were fairly reproducible, with major element RSD <9% and the majority of trace element RSD <8%, with some outlying elements (Cu, Co). On the in-situ sample and the cut surface, similar compositions were measured at different locations, suggesting that samples are chemically homogeneous despite visible variations in appearance. The cut surface measured the lowest major element totals and trace element abundances, and the powder measured the highest. Measurements of standards showed the highest major element totals and results close to certified values, suggesting that the powdered preparation yields the most accurate results. Preliminary comparison of the Bræðravirki palagonite composition to palagonite from Þórisjökull, Iceland (Bedford et al., 2024, doi.org/10.1029/2023JE008261) shows similar compositions. Compared to fresh glass, there is an increase in TiO₂ and decrease in K₂O in the palagonitized samples. Additional measurements on Bræðravirki samples with differing extents of palagonitization will allow us to determine the variability of palagonite’s geochemical “fingerprint.” Future work will determine whether powders can be used to calculate pXRF user factors to correct the internal calibration for in situ measurements. Such an approach could be used to calibrate an instrument on the Mars Rover to identify the presence and chemical composition of palagonite in glaciovolcanic deposits on Mars.