3D volumetric modelling of Cadomian terranes (Northern Brittany, France): an automatic method using Voronoi diagrams

An automatic method based on the use of Voronoi diagrams is proposed for the 3D volumetric reconstruction of geological objects. It enables volumes to be constructed starting from the combined use of geological maps and cross-sections defined in multiple directions, and can also take into account incomplete information on geological interfaces and faults. The method is suitable for global modelling of a set of geological objects; it gives a consistent 3D volumic partition of space according to geological information contained in the maps and the cross-sections. The method is described and applied to modelling the main domains of the Cadomian collisional orogenic belt of Panafrican age in Northern Brittany (France). Thanks to the contrasting densities of the main units involved in the collisional process, the gravimetric effect of the volumic model can be calculated. Its comparison with the observed anomaly allows us to discuss the validity of the geological model. Although some improvements appear to be necessary, it is concluded that the method can make geological modelling more efficient through providing the possibility of rapidly testing many hypotheses. (C) 2001 Elsevier Science B.V. All rights reserved.