Abstract: 4-D Analysis of Analogue Model Experiments

Schreurs, Guido, and Reto Hanni - Geological Institute, University of Bern

About a decade ago the non-destructive X-ray computerized tomography (CT) technique was introduced in geology to analyze analogue models. On the basis of attenuation of X-rays by materials, early X-ray CT scanners produced cross- sectional images through models. Because of the time involved in data acquisition and the required cooling of the X-ray source, these X-ray CT scanners could only compute a 3-D image on the basis of sequential cross-sectional slices at the end of an experiment. Technical developments in recent years have now resulted in more powerful X-ray CT techniques.

We performed analogue model experiments within the investigation field of a helical CT scanner. This new-generation scanner revolves around the model and allows a 4-D analysis of the deforming model by generating time-lapse 3-D volumetric images. 3-D data acquisition depends on material and dosis intensity, but generally lies in the order of about 60 seconds.

Our experiments simulated structures produced by shortening of multi-layer models using brittle and ductile analogue materials. The effects of lateral changes in basal frictional conditions and lateral changes of analogue materials on the resulting structures were investigated. Computer visualization techniques were used to create animations on the basis of CT images and to analyze the structural evolution of our models in 3-D. Visualization shows that lateral changes parallel to the shortening direction induce shallow dipping lateral ramps that connect further advanced thrust fronts with less far-traveled thrust fronts.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil