USING COMPUTED TOMOGRAPHY 3D SCANS IN EXPERIMENTAL SEDIMENTOLOGY

English Abstract:

For decades, experimental sedimentology provided insighful results that improved our understanding of the relationhips between sedimentary processes and preserved deposits, and hence improved our interpretation of the rock record. Now, the non-intrusive CT-Scan technology is allowing refinement of laboratory sedimentological investigations in producing high-resolution 3D records, in time as in space, of both fluid and sediment characteristics simultaneously during sediment transport.

This paper presents a case study from a CT-scan flume (laboratory channel) experiment conducted at the INRS-ETE multidisciplinaty laboratory (http://ctscan.ete.inrs.ca/ ) on the variation in sediment concentration under unidirectional, open-water current, with high yet decreasing flow velocity, and mixed sand/mud clasts. The objective is to better understand sediment transport during unsteady flows and sediment conditions (and related deposits), such as during (following) a flood event. In particular, the question of sediment concentration in the bed-near-bed continuum (5% lower flow deth) was addressed. In this experiment, the flume run trough the CT-scanner, and the density material (water and/or sediment) was measured in over 10⁵volumes (voxels, each approximately equivalent to a grain of 0.8 mm) at various times during the run. Statistical analysis was performed on sediment concentration data over bed/flow profiles. CT-Scan results allow recognition of subtle changes in the shape of relative sediment concentration profile with bed states (plane beds, dunes, ripples), and in bed porosity. Those findings are potentially usefull for environmental studies and reservoir characterization.

This case study demonstrates the great potential of Computed Tomography in process-oriented sedimentology. The community would benefit from collaborative research using this technology, including data sharing as suggested by initiatives such as the Sediment Experimentalists Network (http://workspace.earthcube.org/sen).