contact Cover

 


4.1 Horizontal stratigraphy
In this model an East-West trending valley dissects a simple horizontal layered stratigraphy, so that the outcrop pattern follows the contours of the topography. The results are compared for a barometric survey, where the survey locations are at a constant height above sea level (in this case 400 m above the top of the block), and a draped survey, where the survey locations maintain a constant height above the local land surface (in this case 400 m above the land surface).
Click on the images to launch Noddy. A legend is provided at the end of this page.
 
       
 
Block model showing topography dissecting a three layer stratigraphy.
View geology model
LOAD JPEG IMAGE

In order to use these history files you will also need to download the following  file!  topofile.top 
 
 
Barometric Survey
Draped Survey
Link
Open history with NoddyOpen FracViewer Movie 
Open history with NoddyOpen FracViewer Movie 
Gravity
Open gravity with Noddy
LOAD JPEG IMAGE
Open gravity with Noddy
LOAD JPEG IMAGE
In this image the gravity field only reflects the general shape of the topography, and the position of the high density layer is not immediately obvious.  In this image the gravity field reflects the shape of the topography, and the sharp gradient (which follows the contours) marks the position of the high-density layer. 
Magnetics
Open magnetics with Noddy
LOAD JPEG IMAGE
Open magnetics with Noddy
LOAD JPEG IMAGE
In this image the magnetic field only reflects the general shape of the topography, although there is a strong asymmetry between the North and South facing slopes of the valley, and the exact position of the high susceptibility layer is unclear.  In this image the magnetic field reflects the shape of the topography, and the position of the high susceptibility layer is marked by a low contour-following low on the South-facing slope, and a contour-following high on the North-facing slope. 
Magnetics
Open magnetics with Noddy
LOAD JPEG IMAGE
Open magnetics with Noddy
LOAD JPEG IMAGE
In this image the magnetic field only reflects the general shape of the topography, although there is a strong asymmetry between the North and South facing slopes of the valley, and the exact position of the high susceptibility layer is unclear.  In this image the magnetic field reflects the shape of the topography, and the position of the high susceptibility layer is marked by a low contour-following low on the South-facing slope, and a contour-following high on the North-facing slope. 
Magnetics at Pole
Open magnetics at pole with Noddy
LOAD JPEG IMAGE
Open magnetics at pole with Noddy
LOAD JPEG IMAGE
In this image the magnetic field only reflects the general shape of the topography, and since this image is calculated at the South Pole, the North- and South-facing slopes behave in the same way. The exact position of the high susceptibility layer is unclear.  In this image the magnetic field reflects the shape of the topography, and the position of the high susceptibility layer is marked by a sharp transition in intensity values. 
Magnetics at Pole 1VD
Open magnetics at pole 1VD with Noddy
LOAD TIFF IMAGE
Open magnetics at pole 1VD with Noddy
LOAD TIFF IMAGE
In this image the magnetic field only reflects the general shape of the topography, and since this image is calculated at the South Pole, the North- and South-facing slopes behave in the same way. The exact position of the high susceptibility layer is roughly marked by the sharp transition in intensity values.  In this image the magnetic field reflects the shape of the topography, and the position of the high susceptibility layer is marked by a contour-following dipole anomaly. 

Key
Survey Specifications
Scales
green
k = 0 r = 0
 
green layer
k = 1.1×10-3
 
purple
k = 10-2 r = 3
 
purple layer
k = 0
 
image width
10,000 m
 
 
inclination
50° or 90°
 
intensity
50,000 or 70,000 gamma
 
flying height
400 m
 
 

max

min

max

min

 

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

WWW conversion by Ian Brayshaw