A Matlab Script for Visualizing Structure Contours and Outcrop Patterns in Three Dimensions

Abstract

Structure contours are one of the most important concepts of geological maps, but students often find it difficult to visualize them in three dimensions (3D). A simple Matlab script is presented, which is intended to assist students in the visualization of structure contours in 3D. The currently available versions of the script produce displays of the following types of geological structures: (i) Planes, (ii) sinusoidal folds, (iii) box- and chevron folds, and (iv) folds exhibiting parasitic folding. For simplicity the Earth's surface is defined using simple cosine functions, whilst structures iii and iv are defined using simplified Fourier series. The script is based on a three-step process: (i) Define the topography, (ii) define the geological structure and (iii) establish whether the geological structure is above (eroded) or below the Earth's surface. The last step provides the outcrop pattern. The topography and geology are displayed in 3D and the associated map pattern is plotted in the same diagram. This combination of 3D and 2D plotting provides a direct link between the 3D nature of the structure and its 2D projection (i.e. the map). The 3D diagrams generated with the script have been used successfully in undergraduate geology mapping exercises.