The 3D microscopic ‘signature’ of strain within glacial sediments revealed using X-ray computed microtomography

• Published in: Quaternary science reviews 2011-11, Vol.30 (23), p.3501-3532
• Main Authors: Tarplee, Mark F.V., van der Meer, Jaap J.M., Davis, Graham R.
• Format: Article
• Language: English
• Subjects: Glacial sediments; Micromorphology; Sediment kinematics; Sediment rheology; Subglacial soft sediment deformation; X-ray computed microtomography
• ISSN: 0277-3791; 1873-457X
• DOI: 10.1016/j.quascirev.2011.05.016

X-ray computed microtomography (μCT), a non-destructive analytical technique, was used to create volumetric three-dimensional (3D) models representing the internal composition and structure of undisturbed pro- and subglacial soft sediment sample plugs for the purposes of identifying and analysing kinematic indicators. The technique is introduced and a methodology is presented addressing specific issues relating to the investigation of unlithified, polymineralic sediments. Six samples were selected based on their proximity to ‘type’ brittle and ductile deformation structures, or because of their perceived suitability for successful application of the technique. Analysis of a proglacial ‘ideal’ specimen permitted the 3D geometry of a suite of micro-faults and folds to be investigated and the strain history of the sample reconstructed. The poor contrast achieved in scanning a diamicton of glaciomarine origin is attributable to overconsolidation under normal loading, the sediment demonstrated to have undergone subsequent subglacial deformation. Another overconsolidated diamicton contains an extensive, small scale (