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Mineral Exploration - Using Modern Techniques
Pranit Bhasin
Geoscience Data Services
"With the
privatisation of mineral industries one hopes to see more use
of GIS and Remote Sensing Technology in the country."
Remote Sensing - Remote Sensing (defined as an application) or rather the use of remotely sensed data, i.e: satellite imagery, has been an industry standard first step for the exploration industry, be it mineral or petroleum exploration.
The use of satellite imagery, generally a combination of PAN an dmultispectral in this industry has been use as a base for well planned exploration programs over the last decade, especially with higher resolution imagery available every year. Presently the best imagery is available here in India itself from NRSA (The National Remote Sensing Agency)- the IRS series of satellites, and with the launch of the Earthwatch - Quickbird series of satellites next year by earthwath Inc in the USA, the stage in all set for a revolution in the procurement and use of submeter imagery in the commercial world.
Airborne Methods.
Depending on the purpose of exploration there are a number of airborne techniques used for determining possible target zones and more often cutting exploration costs drastically by narrowing down the area to be covered by detailed ground geophysical studies.
The basic concept remaining the same, which collecting data from equipment aboard a low flying (80m above ground) aircraft at small line intervals. However in India the acceptance of this method of exploration planning has not been wide and the only state to boast of such a database is Orissa. The state now has an extremely marketable and valuable commodity in terms of a digital data base covering 75,000 sq. kms. and incorporating, High resolution Aeromagnetics, radiometrics, digital elevation, satellite imagery, topographical data all collected and collected at 1:50,000 scale.
The advantages of such a program are extensive, and to name a few:
- Reducecosts
Lower field exploration and drilling costs, by identifying target sites for effective use of field resources.
- Find targets
Increase target quality and confidence by integrating all types of data.
- Map geology
Map and understand geological structures with interactive on-screen interpretation and creation of geology maps.
- Print maps
Print professional maps by producing maps for field use,
for management reporting and for investor relations.
Field exploration is expensive and the idea of using an airborne platform integrated with satellite imagery is to identify targets and anomalies from a regional to detailed view. By drilling only those areas showing a high potential, an effective exploration program can be carried out less expensively.
A well collated and structured data base can be sued to:
- Create large scale maps combining multiple airphotos
- Use airphotos to map subregional surface geology
- Show the geological interpretations over airphotos
- Create field exploration maps with detailed views of access roads
- Create 3D views of existing or proposed mines for
planning
A well - structured data base for an effective exploration program will be of the type:
- Satellite Imagery
- Aeromagnetic Interpretations
- Radiometric Interpretations Combined with:
- Available, verified geology
- Topographical data watershed information
All integrated into a powerful GIS creates a valuable pool of data fo then planning an exploration program. A common mistake made in the Indian context is the line of thought that considers Satellite imagery and Aeromgnetic imagery as one and the same. It is important to point out that satellite imagery maps only the superficial ground cover whereas high resolution aeromagnetic maps the unseen or below surface lighology, actual depth depending on the terrain constituents.
Countries such as Malaysia, Indonesia, Australia, The Africas have been generating large revenues from the mining industry, perhaps due to their ability to adopt to this available technology.
Summary
Critics argue that this technology has been used by the public sector for years, however at this point it is important to mention that your data is only as good as the methodology and techniques used to gather this information. For example data collected from a height of 500 or 1000 m with line spacing of half a kilometer will be of little, if any use to the industry especially when compared to data collected form a height of 80m with 200m line spacing.
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