José Manuel Vacas Peña

A COMPUTER PROGRAM FOR THE SIMULATION OF FOLDS OF DIFFERENT SIZES UNDER THE INFLUENCE OF GRAVITY

Folding&g is a computer program, based on the finite element method, developed to simulate the process of natural folding from small to large scales in two dimensions. Written in Pascal code and compiled with Borland Delphi 3.0, the program has a friendly interactive user interface and can be used for research as well as educational purposes. Four main menu options allow the user to import or to build and to save a model data file, select the type of graphic output, introduce and modify several physical parameters and enter the calculation routines. The program employs isoparametric, initially rectangular elements with eight nodes, which can sustain large deformations. The mathematical procedure is based on the elasticity equations, but has been modified to simulate a viscous rheology, either linear or of power-law type. The parameters to be introduced include either the linear viscosity, or, when the viscosity is non-linear, the material constant, activation energy, temperature and power of the differential stress. All the parameters can be set by rows, which simulate layers. A toggle permits gravity to be introduced into the calculations. In this case, the density of the different rows must be specified, and the sizes of the finite elements and of the whole model become meaningful. Viscosity values can also be assigned to blocks of several rows and columns, which permits the modelling of heterogeneities such as rectangular areas of high strength, which can be used to simulate shearing components interfering with the buckling process. The program is applied to several cases of folding, including a single competent bed and multilayers, and its results compared with analytical and experimental results. The influence of gravity is illustrated by the modelling of diapiric structures and of a large recumbent fold.

The efieldbook program: A teaching resource for geology

The eFieldBook program is a geology teaching tool with high didactic potential that guides a students work in the field using multimedia and other resources. This program allows the collection of geo-referenced geological information as well as its storage and transmission, if necessary, as soon as it is collected. The data can be collected as in traditional field notebooks or on maps and photographs. The information can be used as soon as it is collected and can be exported to other programs such as Word, Excel, Georient or statistical packages. eFieldBook safely stores and backs up user information by sending any data collected to a selected Internet target at regular time intervals.