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6.2 Enrichment alteration halo around a plug

This model shows the results of emplacing a plug in an area of tilted folds. The density and susceptibility values are modelled as enrichment haloes where the rock properties are varied as a function of distance from the plug, before returning to normal as the distance away increases.
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	LOAD JPEG IMAGE Block diagram of unaltered geology Block diagram showing the geology of the model with plug intrusion but no alteration halo. The top layer has been removed to show the internal structure of the model. Colours are used simply to highlight the structures.
LOAD JPEG IMAGE Block diagram showing density variations in altered geology Block diagram showing the geology of the model with plug intrusion and alteration halo. The top layer has been removed to show the internal structure of the model. Colours are used to demonstrate density variations, using a rainbow look up table.		LOAD JPEG IMAGE Block diagram showing magnetic susceptibility variations in altered geology Block diagram showing the geology of the model with plug intrusion but no alteration halo. The top layer has been removed to show the internal structure of the model. Colours are used to demonstrate magnetic susceptibility variations, using a rainbow look up table.

Link	Gravity	Magnetics	Magnetics	Magnetics at Pole	Magnetics at Pole 1VD
No alteration	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Note the relatively uniform intensity values (except at the north plunging hinge) in the folded layer.	Note the relatively uniform intensity values (except at the north plunging hinge) in the folded layer.		Note the relatively uniform intensity values in the folded layer.	Note the relatively uniform intensity values (except at the north plunging hinge) in the folded layer.
Alteration	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE	LOAD JPEG IMAGE
	Note the strong localisation of the high intensity field in the parts of the folded layer adjacent to the plug.	Note the strong localisation of the high intensity field in the parts of the folded layer adjacent to the plug.	Note the relatively uniform intensity values (except at the north plunging hinge) in the folded layer.	Note the strong localisation of the high intensity field in the parts of the folded layer adjacent to the plug.	Note the strong localisation of the high intensity field in the parts of the folded layer adjacent to the plug.

Key	Survey Specifications	Scales
red r = 2.9 k = 10-3 background r = 2.4 k = 5×10-5 plug r = 2.5 k = 1.7×10-4 image width 10,000 m	inclination 50° or 90° intensities 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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