Movie B-3. Extension experiment

4D evolution of part of the model illustrated by successive 3D perspective views. The area covered by X-ray CT analysis is shown in Figure 7 (see accompanying paper). The width between the conjugate faults that form at early stages of extension reflects the depth to the underlying viscous layer. In the part of the model where there is only one basal viscous layer (SE side of block), the width between conjugate faults is large, whereas in the part of the model with a second viscous layer embedded in brittle layers (NW side of block), this width is small. The domains are separated by an extensional transfer zone that is oriented parallel to the extension direction. Each movie frame represents a perspective 3D cut-out view that was constructed from a 3D volume consisting of 80 serial cross-sections. Each cross-section represents a 2 mm thick CT slice. The discontinuity near the left-hand side of each block results from missing cross-sections. Longest dimension of view is 26.5 cm. Extension increment between each movie frame is 5 mm. Viscous PDMS = red, quartz sand = yellow-orange, corundum sand = yellow.