3-D visualization of structural field data: examples from the Archean Caopatina Formation, Abitibi greenstone belt, Quebec, Canada

A series of 3-D visualization approaches is presented with the aim of developing better interpretation tools for field-based geologists. Structural data from outcrop, mine and regional scales are used to create speculative 3-D surfaces that can be useful in addressing geological problems. These tools could help in resolving cryptic early fold geometries, extending stratiform mineralizations and the sub-surface interpretation of regional thrusts, unconformities or key lithostratigraphic boundaries. Using sparse data sets from the low-relief and structurally complex Archean Ability greenstone belt, I have demonstrated that speculative models can be created from such challenging terrains, provided that existing data are respected and that appropriate methods are applied at a given scale. Examples focus on optimizing the 3-D editing environment for making better interpretations. Applied techniques include custom projections of surface traces, 3-D digitizing, simple Bezier surface patches, and noncylindrical fold construction using held based plunge models. These are implemented as several UNIX AWK programs in conjunction with commercial 3-D visualization and modeling software gOcad(C) and EarthVision(C). This Integration and visualization study shows that complex fold geometries can be more rigorously constructed using constraining structural field data, but that current 3-D technologies are still very cumbersome for hard rock applications. Future development of field based case studies that will help validate and communicate the benefit of these methods is much needed, and will hopefully better articulate specific requirements to software developers. Professional 3-D software developers are encouraged to work towards the implementation of these types of programs in order to move the regional mapping community beyond 2-D and 21/2-D GIS-based modeling. National surveys and explorationists who are responsible for the collection, management, and archiving of geoscience data need to be diligent in maintaining their structural field data. This will be especially critical as 3-D visualization and modeling techniques, such as those I have presented here, become available to the bedrock mapping community. (C) 2000 Elsevier Science Ltd. All rights reserved.