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5.2 Remanence and folding


This set of models shows three possible interactions of folding with a remanent component to magnetisation. The first row of models have no remanent component, the second row has a remanently magnetised layer with remanence imposed after folding, and the third row has a remanent layer with vectors deflected by the folding. While the overall fold geometry is apparent in all three models, because the total magnetic moment of the layer still in general contrasts strongly with the background, the folded remanence models show marked variation in field intensity for different fold limbs.

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Map of remanence vectors

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Map showing dip and dip direction values for remanence vector at selected positions.

 
Block diagram of folded layer

View geology model

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In this model the remanence is non-existant or uniform in orientation.

Block diagram of folded layer

View geology model

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In this model the remanence orientation varies according to position on the fold. Colours vary with the declination of the remanence.

Link
Magnetics
Magnetics
Magnetics at Pole
Magnetics at Pole 1VD
No remanence

Open history with NoddyOpen FracViewer Movie
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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Post-folding remanence

Open history with NoddyOpen FracViewer Movie
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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Remanence uniformly set to:
inclination0
declination090
intensity1000
Remanence uniformly set to:
inclination0
declination090
intensity1000
   
Pre-folding remanence

Open history with NoddyOpen FracViewer Movie
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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Remanence set to:
inclinationvariable
declinationvariable
intensity1000
Remanence set to:
inclinationvariable
declinationvariable
intensity1000
   

Key
Survey Specifications
Scales
layer
k = 10-2
background
k = 10-4
image width
10,000 m
inclination
50° or 90°
intensity
50,000 or 70,000 gamma
flying height
80 m

max



min

max



min

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

WWW conversion by Ian Brayshaw