Geometrical analysis of folded surfaces using simple functions

Citation
F. Bastida et al., Geometrical analysis of folded surfaces using simple functions, J STRUC GEO, 21(7), 1999, pp. 729-742
Citations number
16
Categorie Soggetti
Earth Sciences
Journal title
JOURNAL OF STRUCTURAL GEOLOGY
ISSN journal
01918141 → ACNP
Volume
21
Issue
7
Year of publication
1999
Pages
729 - 742
Database
ISI
SICI code
0191-8141(199907)21:7<729:GAOFSU>2.0.ZU;2-S
Abstract
Several functions have been chosen in order to approximate fold profile geo metry. Some of them are valid mainly for alloclinal folds (interlimb angle> 0), whereas others are mainly valid for isoclinal folds (interlimb angle = 0). In all cases, a fold profile can be characterised by an aspect ratio (y (0)/x(0)) between the height and the width of a limb (fold amplitude), and a shape parameter characteristic of the considered function. The shape para meters have been mutually linked through the area beneath the fold profile. The geometrical analysis enables a graphical classification based on a sha pe-amplitude diagram in which the most common types of folded surfaces are represented: cuspate, chevron, sinusoidal, parabolic, elliptic and box fold s. Any of the shape parameters can be used as x-axis of the diagram in orde r to approximate the geometries commonly exhibited by natural folds. In the diagram presented in this paper two shape parameters have been combined: t he exponent n of a power function for alloclinal folds, and a parameter C/y (0), defined from a function composed of an elliptic part and a line segmen t of length C for isoclinal folds. In order to show the suitability of the classification method, it has been applied to some examples of finite-eleme nt, experimental and natural folds. (C) 1999 Elsevier Science Ltd. All righ ts reserved.