Computerized coaxial tomography (CT-Scanning) in paleoclimatic studies.

• Main Authors: Francus, Pierre, Lapointe, François, Massa, Charly, Fortin, David, Kanamaru, Kinuyo, St-Onge, Guillaume
• Format: Other/Unknown Material
• Language: unknown
• Published: 2015
• Subjects: tomographie; études paléoclimatiques; Ellesmere Island; Strathcona; Agassiz Ice Cap; Ice cap
• Online Access: https://espace.inrs.ca/id/eprint/4306/

Medical CT-Scanners allow the rapid 3D visualisation of sediment cores. CT-Scans images correspond to 3-D linear X-ray attenuation pixel or voxel matrix, where higher density and higher atomic numbers result in higher attenuation of X-rays. This paper illustrates that CT-scanning sediment cores is a powerful tool to identify and visualize, amongst others, physical sedimentary structures (e.g. turbidites), biogenic structures (e.g. bioturbation), coring artefacts, sediment disturbances, hiatus and other erosional features, and therefore is a powerful tool to establish a high-resolution stratigraphy. Moreover, it can be used to establish physical properties of sediments, such as density. This paper presents a comparison of density measurements obtained from CT-Scans images with conventional measurements (Gamma-Ray attenuation, bulk density) over a 100m-long sediment profile and evaluate the quality, sources of error and the comparative advantages of the different methods in terms of accuracy of the signal, and time necessary to perform analyses. Finally, we applied this technique to the varved sediments of Strathcona Lake sediment, northern Ellesmere Island, in order to obtain annually resolved sedimentary fluxes. Over the last 65 years, annual sediment accumulation rates in Strathcona Lake documented an increase in high-energy hydrologic discharge events from 1990 to 2009. This timing is in agreement with evidence for an increase in the amount of melt on the adjacent Agassiz Ice Cap, as recorded in ice cores.