T289 Folds: Causes and Consequences (Posters)

Tuesday, 24 October 2017
9:00 AM - 6:30 PM
Halls 4EF

INTERPRETATION OF PERICLINES USING 2D OBSERVATION METHODS

Paper number: T289-2
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

The use of stereographic projections in determining the overall shape of a geologic structure is widely adopted amongst geologists. However, the use of a stereonet or tangent plot alone in discerning the orientation of a 3D structure may be misleading. For example, a pericline (doubly plunging anticline) will plot differently on a stereonet based on the location of the measurements. This study aims to investigate the insufficiencies of using a two-dimensional view to analyze a three-dimensional structure. Such a problem is encountered commonly in field outcrops of fold systems that are partially exposed in a cross-sectional view (e.g. in roadcuts). In this study, using the finite element pre-processing software package Altair HyperMesh™, nodes from discretized periclinal structures are used to calculate the attitude of the elements within the structure. Different simulated roadcuts are used to extract multiple sets of orientation data. Calculated orientations are plotted on stereonets and tangent plots for further analysis. Based on the specific set of elements used, the resulting stereonet reflects different geologic structures which may be observed on roadcuts oriented in differing directions. For example, a vertical elliptical cone could be interpreted from a periclinal cut. These alternative interpretations are found from analyzing few and specific datasets of the original structure. The results based on 3D periclinal structures indicate several different structures can be interpreted through stereographic reconstructions of various cross-sectional views. For example, periclinal structures may show up as cones but do not follow the stereonet pattern of a cone. Therefore, it is necessary for three-dimensional structures to be based on a dataset that covers a significant portion of the structure to accurately describe the geometry and orientation for analysis.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-295990

© Copyright 2017 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.