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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.
Open FracViewer MovieSummary 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

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Open gravity with Noddy

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Open magnetics with Noddy

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Open magnetics with Noddy

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Open magnetics at pole with Noddy

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Open magnetics at pole 1VD with Noddy

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Notice the full EW and NS symmetry of gravity and EW symmetry of the magnetic images.
Sinusoidal folds plunging 45° to North

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Open gravity with Noddy

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Open magnetics with Noddy

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Open magnetics with Noddy

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Open magnetics at pole with Noddy

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Open magnetics at pole 1VD with Noddy

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Both gravity and magnetic images now only show EW symmetry.
Sinusoidal folds plunging 20° to North

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Open gravity with Noddy

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Open magnetics with Noddy

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Open magnetics with Noddy

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Open magnetics at pole with Noddy

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Open magnetics at pole 1VD with Noddy

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Both gravity and magnetic images now only show EW symmetry, with exaggerated differences between North and South hinges.
Sinusoidal folds reclined 45° to East

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Open gravity with Noddy

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Open magnetics with Noddy

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Open magnetics with Noddy

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Open magnetics at pole with Noddy

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Open magnetics at pole 1VD with Noddy

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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

Open history with Noddy Open FracViewer Movie Open Geology VRML
View geology model

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Open gravity with Noddy

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Open magnetics with Noddy

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Open magnetics with Noddy

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Open magnetics at pole with Noddy

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Open magnetics at pole 1VD with Noddy

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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 = 1k = 10-2
background
r = 0k = 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