Investigating Sedimentary Systems at a Basin Scale Using GIS: Examples from the Champsaur Sandstones of Southeast France

Rufus L. Brunt¹, William D. McCaffrey², and Robert W. H. Butler^2
1 University of Liverpool, Liverpool, United Kingdom
² University of Leeds, Leeds, United Kingdom

The use of Geographical Information Systems (GIS) to visualise and interpret geological systems in outcrop is increasing as archives of aerial/ satellite imagery become more accessible and the necessary software decreases in price and complexity. A key GIS technique is the direct use of aerial photogrammetry to construct digital elevation models (DEMs). Digital or ‘virtual' models may then be produced by draping maps, aerial imagery or photographs over the base DEM. The virtual model may be viewed from positions optimal in resolving the geometric form of features that are not easily seen from ground level. Recording positional data of features developed on a scale larger than the uncertainty of the DEM may be rapidly accomplished on a basinal scale.

The Champsaur basin, a sub basin within the Alpine foreland basin of SE France was investigated using GIS techniques. The predominantly turbiditic fill of the Champsaur basin was subject to both syn- and post-sedimentary compressional deformation. A DEM totalling >250 km² was constructed for this area with a mean horizontal and vertical resolution of <4 m. A virtual model constructed by draping orthorectified aerial photographs over the DEM was then used to conduct an investigation of large- scale sedimentary features, and more specifically turbidite architectural bounding surfaces. The outcrop trace of architectural surfaces were mapped for distances in excess of 10 km, and between adjactent valleys, enabling the construction of a comprehensive model of the sedimentary architecture, with both research and teaching applications.