75 Mineralogy, Geochemistry, Petrology, and Volcanology Student Session (Posters)

GSA’s MGPV student representatives invite the division’s student population to present their research (oral or poster). We encourage abstracts from any subdiscipline within our respective fields with hopes of stimulating a multi-disciplinary, early career researcher (ECR) community within MGPV.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Assessing Inter-Sample Elemental Variability and Sample Preparation Methodology in Handheld X-ray Fluorescence (XRF)

Paper number: 75-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The use of portable X-ray fluorescence (XRF) as an analytical tool for qualitative assessment of the mineralogical and geochemical characteristics of sediment samples is non-destructive and relatively cost-effective. Additionally, this tool provides a large amount of data to interpret past environments and chemical processes. Because of these reasons, XRF is widely used for environmental reconstructions across geologic disciplines. Recovered XRF signals are impacted by porosity, a factor that becomes especially important in near-shore and/or coarser-grained lithologies, since variations in density can alter elemental counts and lead to inconsistent results. As such, understanding the variability within samples collected from the same lithologic stratum and recognizing the effects of varying porosity is important when evaluating portable XRF results. In this study, rock samples representing three general lithologies (i.e. limestone, calcareous mudstone, and black shale) were collected from four stratigraphic sections across/representing three formations: two carbonate-rich layers of the Massie Formation (Indiana, USA), the Green River Formation (Wyoming and Colorado, USA), and the Stark Shale Member of the Dennis Formation (Missouri, USA). All samples were powdered in a ball mill prior to preparation. Ten samples from each section (40 total) underwent two different preparation methods: cups (sediment was simply placed into small cups) and pellets (sediment was powdered and then pressed into pellets at 2000 psi) Elemental analysis was conducted on cup and pelleted samples using a Bruker Tracer III-SD handheld XRF. To quantify these differences, multivariate statistical analyses were conducted to determine whether there is a significant difference in the mineralogy and geochemistry of samples of similar lithology and stratigraphy, as well as to determine whether significant differences exist between sample preparation methodologies. By quantitatively testing if different sample preparation methods matter, the results of this study provide insight on the effects of porosity when conducting portable XRF analysis (i.e., handheld or mounted). In addition, determining whether there are significant differences within the same lithologic strata or unit may provide nuance(s) when interpreting portable XRF results.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414652

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