Application of younging tables to the construction of relative deformationhistories - 1: Fracture systems

For a collection of age relationships there are several possible histories. Younging tables provide a simple and direct method with which all valid de formation histories can be identified. The application of this technique to Fracture systems is illustrated using two case studies. These examples dem onstrate how unobserved relationships, synchronous structures, and fracture s that appear in more than one stage of a deformation history can be dealt with using younging tables. Suggestions are made for the presentation of re lative deformation histories that highlight ambiguities and convey a visual impression of the confidence that may be placed on a particular history. A pplication of the approach to the analysis of grain fragmentation has ident ified a range of multi-stage deformation histories. All of these histories involve, to a greater or lesser extent, the operation of extension fracture s, shear fractures, linked shear fractures and extension fractures, and sev eral sets of synchronous extension fractures. Analysis of an exposed fractu re system using younging tables has raised the possibility of the simultane ous growth of two sets of orthogonal extension fractures with the implicati on that the scale of stress homogeneity may be only a few metres. (C) 2000 Elsevier Science Ltd. All rights reserved.