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 th e 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 in complete 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 geologica l information contained in the maps and the cross-sections. The method is d escribed and applied to modelling the main domains of the Cadomian collisio nal orogenic belt of Panafrican age in Northern Brittany (France). Thanks t o the contrasting densities of the main units involved in the collisional p rocess, the gravimetric effect of the volumic model can be calculated. Its comparison with the observed anomaly allows us to discuss the validity of t he geological model. Although some improvements appear to be necessary, it is concluded that the method can make geological modelling more efficient t hrough providing the possibility of rapidly testing many hypotheses. (C) 20 01 Elsevier Science B.V. All rights reserved.