Exploring the application of dual‐energy CT to discriminate sediment facies in a varved sequence

• Published in: The depositional record Vol. 10; no. 1; pp. 231 - 244
• Main Authors: Martini, M., Francus, P., Di Schiavi Trotta, L., Letellier, P., Des Roches, M., Després, P.
• Format: Journal Article
• Language: English
• Published: Hoboken John Wiley & Sons, Inc 01.02.2024; Wiley
• Subjects: 3D visualisation; Calibration; Chemical composition; Computed tomography; debris flow; Energy; Geochemistry; geomaterials; non‐destructive analysis; Porosity; Scanners; Sediments; turbidity; X‐ray tomography; Canada; Arctic region
• ISSN: 2055-4877; 2055-4877
• DOI: 10.1002/dep2.271

Dual‐energy X‐ray computed tomography consists of imaging objects using two incident X‐ray beams of different energy to distinguish the different compounds within a sample based on their density (electron density, ρe) and elemental composition (effective atomic number, Zeff). The stoichiometric calibration for dual‐energy X‐ray computed tomography was already successfully implemented to identify single and homogeneous minerals easily and non‐destructively. It is here applied for the first time to a more complex and heterogeneous sample, a varved sediment core with three distinct facies. The output of dual‐energy X‐ray computed tomography was compared against elemental geochemistry obtained at the same resolution using a micro‐XRF core scanner. The three individual facies can be successfully differentiated using dual‐energy X‐ray computed tomography because their range of ρe and Zeff values allow their discrimination. Correlations with elemental geochemistry are also discussed but are less conclusive, probably because of variations in grain size and porosity, and because these high resolution analyses were not performed at the exact same location. The paper not only eventually discusses the limitations when using dual‐energy X‐ray computed tomography on sediments but also demonstrates its potential to quantitatively study sediment cores in a non‐destructive way. Dual‐energy X‐ray computed tomography (DECT) allows materials to be distinguished in a non‐destructive way based on their density and their chemical composition. A stoichiometric calibration for DECT is applied for the first time to a varved sedimentary sequence. Three distinct facies have been distinguished by DECT. DECT can be applied to all kind of sediments in the future; the limitations and potential of the technique are discussed.