 |
Home | Overview | Magnetics Basics | Magnetic Properties | Top
This page is an edited version of a class presentation, not a full set of subject notes.
Preview Mapping
- Geophysical data are basic resources
- Governments underwrite acquisition, to promote activity
- VIMP, BHEI, Discovery 2000 just three recent examples
- Enable significant understanding before other fieldwork
Second-Generation Mapping
- Heavy bias to newer remote-sensing methods
- High-resolution airborne magnetics
- High-resolution airborne radiometrics
- GIS methods to integrate new information, existing information, lab studies
- Basis changed in order to target hard-rock geology beneath cover
Examples of new data sets
- Images follow of an area of Northern Victoria, roughly 150 km wide. (Detail not apparent at this scale.)
- Digital elevation
- Total-field Magnetics Variation
- Gamma-Ray spectrometry
- Compare with pre-existing geology
Click on the thumbnails to see a larger version of the images. A Geographical Information System (GIS) might use these images as backgrounds to display other kinds of data.
|
Bendigo Region Topographic Data
- Digital Elevation Model, from airborne survey
|
Bendigo Region Radiometric Data
- Acquired from airborne survey
- Red=K, Blue=U, Green=Th
|
|
Bendigo Region Magnetic Data
- Acquired from airborne survey
- Red=higher, Blue=lower magnetic field strength
|
Existing Geology
- Taken from 1:1M State Geological Map
- Note: White, yellow, green are cover
- (Scale slightly different in this image)
|
Source: AGSO Journal of Australian Geology and Geophysics, volume 17(2), 1997
Coverage is uniform
- Uniformity of survey coverage is significant contribution to utility
- Uniformity does not mean rigidity
- Image processing, math manipulation allow different "products" to be made available
- Different products enhance different aspects of structure, lithology, petrology
- GIS fundamental to integration
Further example - Pilbara, WA
This example, from the Northeast Pilbara Project, can be viewed at the relevant AGSO website. If you are really focussed, you can buy a copy there.
Tools for Modern Mapping
- Next segment concentrates on basics of magnetic method
- Much image assessment possible from "pattern recognition"
- Folds look like folds; offsets are likely faults, in features in magnetic images just as in outcrop maps
- More information about the source structure is available, especially about depth, if mechanisms producing the magnetic responses are understood
Home | Overview | Magnetics Basics | Magnetic Properties | Top
|
