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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 LOAD JPEG IMAGE Map showing dip and dip direction values for remanence vector at selected positions.
Block diagram of folded layer LOAD JPEG IMAGE In this model the remanence is non-existant or uniform in orientation.		Block diagram of folded layer LOAD JPEG IMAGE 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	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
Post-folding remanence	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Remanence uniformly set to: inclination 0 declination 090 intensity 1000	Remanence uniformly set to: inclination 0 declination 090 intensity 1000
Pre-folding remanence	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Remanence set to: inclination variable declination variable intensity 1000	Remanence set to: inclination variable declination variable intensity 1000

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

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Copyright © 1998-2002 AGCRC & Mark Jessell

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