Analysis of analogue models by helical X-ray computed tomography

Abstract

The aim of analogue model experiments in geology is to simulate structures in nature under specific imposed boundary conditions using materials whose rheological properties are similar to those of rocks in nature. In the late 1980s, X-ray computed tomography (CT) was first applied to the analysis of such models. In early studies only a limited number of cross-sectional slices could be recorded because of the time involved in CT data acquisition, the long cooling periods for the X-ray source and computational capacity. Technological improvements presently allow an almost unlimited number of closely spaced serial cross-sections to be acquired and calculated. Computer visualization software allows a full 3D analysis of every recorded stage. Such analyses are especially valuable when trying to understand complex geological structures, commonly with lateral changes in 3D geometry. Periodic acquisition of volumetric data sets in the course of the experiment makes it possible to carry out a 4D analysis of the model, i.e. 3D analysis through time. Examples are shown of 4D analysis of analogue models that tested the influence of lateral rheological changes on the structures obtained in contractional and extensional settings.Supplementary material: The nineteen movies referred to in the article are available at https://doi.org/10.6084/m9.figshare.c.4788519

An Inside Perspective on Magma Intrusion: Quantifying 3D Displacement and Strain in Laboratory Experiments by Dynamic X-Ray Computed Tomography

“…X-ray Computed Tomography (CT) provides a solution to observe the interior of laboratory models with granular host material (Mees et al, 2003;Kervyn et al, 2010;Cnudde and Boone, 2013). While high-resolution micro-CT scanners only allow imaging of the final model geometry (Kervyn et al, 2010;Poppe et al, 2015), medical scanners can acquire a time-series of 3D CT images at any desirable time interval, but at the cost of lower spatial resolutions (Schreurs et al, 2003). This technique has been used to image structural geometries in sandbox models simulating tectonic compression (Adam et al, 2013) or extension (Holland et al, 2011;Zwaan et al, 2018), or viscous magma intrusion in a sand-plaster cone (Rincón et al, 2018).…”

“…This technique has been used to image structural geometries in sandbox models simulating tectonic compression (Adam et al, 2013) or extension (Holland et al, 2011;Zwaan et al, 2018), or viscous magma intrusion in a sand-plaster cone (Rincón et al, 2018). Standard CT scanners have narrow X-ray detectors and only allow for "helical scanning" by moving the model box through the X-ray gantry while experimental deformation has to be arrested (Schreurs et al, 2003). The recent development of Digital Volume Correlation (DVC) techniques enables one to quantify displacement and strain in 4D throughout the entire laboratory model volume (Adam et al, 2013;Zwaan et al, 2018).…”

Seismic imaging of sandbox experiments – laboratory hardware setup and first reflection seismic sections

“…Thus, direct observation of deformation is only possible at the surface of 3-D models or through bordering glass planes of 2-D models. Although recently new monitoring techniques like X-ray computer tomography (Coletta et al, 1991;Schreurs et al, 2003), particle image velocimetry (PIV, e.g. Baldassarre et al, 2001;Wolf et al, 2003;Hampel et al, 2004;Adam et al, 2005;Rosenau et al, 2009;Reiter et al, 2011), or laser scanning (e.g.…”

“…Even though X-ray computerized tomography (CT) analysis also allows the visualization of the interior of an analogue model without destroying it (Colletta et al, 1991;Schreurs et al, 2003), it still requires the analysis of distinct scenes of an evolving model sequence (see Holland et al, 2011). Here, we introduce the new laboratory facility and its technical specifications, and also discuss the tested geometry and material variations based on the first data generation produced by multiple-offset surveying.…”

3D imaging of volcano gravitational deformation by computerized X-ray micro-tomography

“…Computerized X-ray tomography (CT), as a non-destructive imaging system, has the capability to enable the 3D reconstruction of analogue models, permitting virtual cross-sections and the documentation of the 3D complexity of structures. This technique has been used to document analogue models simulating 2D tectonic deformation in compressive (e.g., Colletta et al, 1991;Schreurs et al, 2001), transcurrent (e.g., Schreurs, 1994;Ueta et al, 2000) and extensional (e.g., Mandl, 1988;Schreurs et al, 2003) regimes. These applications used a medical X-ray scanner, providing parallel X-ray cross-sections through the model, at intervals of a millimeter to several centimeters.…”