contact Cover

2.1.4 Ambiguities in the interpretation of sinusoidal folds

This sequence of images shows the effect of varying the orientation, amplitude and wave-length of sinusoidally folded 200 m thick layer in such a way that the outcrop pattens remain the same.

All block diagrams are viewed from SW. Summary wavelet transform animation comparing 3 different orientations


Click on the images to launch Noddy. A legend is provided at the end of this page.

Link	Block	Gravity	Magnetics	Magnetics	Magnetics at Pole	Magnetics at Pole 1VD
Sinusoidal folds plunging vertically	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Notice the full EW and NS symmetry of gravity and EW symmetry of the magnetic images.
Sinusoidal folds plunging 45° to North	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Both gravity and magnetic images now only show EW symmetry.
Sinusoidal folds plunging 20° to North	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Both gravity and magnetic images now only show EW symmetry, with exaggerated differences between North and South hinges.
Sinusoidal folds reclined 45° to East	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	The EW symmetry has now broken down in the gravity and magnetic images, and the magnetic images show neither EW or NS symmetries.
Sinusoidal folds reclined 20° to East	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Notice the EW trending high background band in the gravity and oblique tails off the North hinges of the folds in the magnetic image.

Key	Survey Parameters	Scales
layer r = 1 k = 10-2 background r = 0 k = 0 image width 10,000 m	Inclination 50° Intensity 50,000 or 70,000 gamma Flight height 80 m	max min max min

All models created using Noddy
Copyright © 1998-2002 AGCRC & Mark Jessell

WWW conversion by Ian Brayshaw