--> Abstract: Quantitative Analysis of the Structural Evolution in a 4-D-Analogue Sandbox Experiment to Constrain Models of Palinspastic Restoration, by William Sassi, Graham Seed, Ryan Shackleton, Zsolt Schleder, and Ahmed M. Saeed; #90078 (2008)

Datapages, Inc.Print this page

Quantitative Analysis of the Structural Evolution in a 4-D-Analogue Sandbox Experiment to Constrain Models of Palinspastic Restoration

William Sassi1, Graham Seed2, Ryan Shackleton2, Zsolt Schleder2, and Ahmed M. Saeed2
1Structural Geology, IFP, Rueil-Malmaison, France
2Midland Valley Exploration, Glasgow, United Kingdom

A 4D-analogue sandbox experiment imaged by X-ray computer tomography analysis was numerically digitized to quantify the evolution of deformation and fault development within two layers of granular materials. Two major phases of deformation were applied, the first produced a central and elongated horst and graben fault system. The second was sinistral transpression with the shortening applied perpendicular to the horst-graben mean axis. Between the two phases, sediments were added by infilling the central depression with sand and adding a thin layer of silicone polymer and a thicker upper layer of sand and corundum.

In total, 15 discrete block-diagrams were digitized to document the structural evolution of the sandbox. For each block, 57 cross sections and 141 horizontal slices were available. Measured parameters included line length and surface area for the topography and the sand/silicon horizons, and the geometry and orientation of faults. Results have revealed the chronology of fault development in great detail, showing that reverse faulting inducing basin inversion occurred after 10% strain of net compression. From 0 to 10% strain there is a regular shrinking of all the surfaces, and between 10 to 20% strain faulting induced a wider scattering in line length distribution. At the final stage, the surface topography lost over 20% in area, and the interfaces of the lower horizons also reduced in area by 17%. This change was clearly due to the permanent deformation and the increase in thickness by faulting is the compensating factor. Curvature analysis of the surface horizons facilitates the detection of regions of second order variations which can highlight either artefacts or real relief due to structural features. Prediction of these latter elements is of paramount importance for interpretation of seismic data sets.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas