Authors:

Hannah Nicole Tharrington

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About Paper:

Magnetite (Fe3O4) is a mineral that is common in Earth's crust across a wide range of geologic environments. Geologists would like to utilize measurements of helium (He) isotopes in magnetite for geo- and thermochronology, i.e., to determine the timing and rates of geologic events and processes. In order to successfully use magnetite for He- based chronology, we need to characterize and understand the different potential sources of He, which can include radioactive decay, cosmic ray interactions, and nuclear reactions within magnetite. This research uses various analytical techniques to characterize these different sources within magnetite samples that we will later use to measure helium diffusion kinetics and determine surface erosion rates. To account for extraneous radiogenic He from mineral inclusions, we used Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) to determine the presence, distribution, and composition of potential mineral inclusions. We also used X-ray Computed Tomography (XCT) data to map the spatial distributions of inclusions in 3 dimensions and referenced these data against the SEM/EDS data. To account for nucleogenic He produced by (alpha,n) reactions of lithium, we also measured lithium concentrations by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis. The results of these analyses can be used to evaluate the potential sources of helium within the magnetite and its further applications with regards to geo- and thermochronology. Keywords: Magnetite; Thermochronology; Geochronology; Helium Isotopes

Source:

Purdue University / 2025

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Co-authors:

Hannah Nicole Tharrington