Satellite Imagery Usage For Mining Exploration

 

A geographics information system (GIS) is a computer system for capturing, storing, checking, and displaying data related to positions on Earth’s surface. GIS can show many different kinds of data on one map. This enables people to more easily see, analyze, and understand patterns and relationships. 

With GIS technology, people can compare the locations of different things in order to discover how they relate to each other. For example, using GIS, the same map could include sites that produce pollution, such as gas stations, and sites that are sensitive to pollution, such as wetlands. Such a map would help people determine which wetlands are most at risk.

Satellite Remote Sensing has been a standard first step for the mineral and petroleum exploration industry. Satellite imagery from satellite sensors such as GeoEye-1, WorldView-2, QuickBird, IKONOS, ASTER and LANDSAT 7 +ETM have benefited geologists, scientists and exploration managers in earth sciences due to the advantage of large scale mapping and the sensors containing multiple band colors which allows them to interpret wavelengths that cannot be seen by the human eye, such as near infrared, short wave infrared and thermal infrared to identify the difference in structural features of the earth’s surface.

 IKONOS Satellite Image of Mining Operations in Nevada

Multispectral imaging and thematic mapping allows researchers to collect data of reflection and absorption properties of soils, rock, and vegetation. This data could be utilized to interpret actual surface lithology to identify clays, oxides and soils from satellite images.

The use of satellite imagery in mineral exploration, generally a combination of panchromatic and multispectral image data has been used in mineral and petroleum industries over the last decade. With higher resolution satellite sensors increasing over the last decade such as GeoEye-1 (0.41m) and WorldView-2 (0.46m) both providing panchromatic and multispectral full color imagery that is used to utilize enhanced spectral analysis for mapping, monitoring and analyzing landcover classification and extraction of culture data, normalized difference vegetation index (NDVI) classification and mapping, lithological classification, change detection, environmental monitoring,  development, land-use planning, visualization and simulation environments such as digital elevation models (DEMs) and 3d terrain modeling.

ASTER (15m) Satellite Images of Escondida open-pit mine in Atacama Desert, Chile

This ASTER image covers 30 by 37 km in the Atacama Desert, Chile and was acquired on April 23, 2000. The Escondida Cu-Au-Ag open-pit mine is at an elevation of 3050 m, and came on stream in 1990. Escondida is related geologically to three porphyry bodies intruded along the Chilean West Fissure Fault System. A high grade supergene cap overlies primary sulfide ore. The top image is a conventional 3-2-1 RGB composite. The bottom image displays SWIR bands 4-6-8 in RGB, and highlights lithologic and alteration differences of surface units. Imagery Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

Geologists and Geoscientists have used satellite images to serve as databases from which they can do the following:

1. Pick out rock units (stratigraphy)
2. Study the expression and modes of the origin of landforms (geomorphology)
3. Determine the structural arrangements of disturbed strata (folds and faults)
4. Evaluate dynamic changes from natural events (e.g., floods; volcanic eruptions)
5. Seek surface clues (such as alteration and other signs of mineralization) to subsurface deposits of ore minerals, oil and gas, and groundwater.
6. Function as a visual base on which a geologic map is drawn either directly or on a transparent overlay.
7. digital elevation model argyle_view_diamond_mine_3d

ASTER Satellite Image of Argyle Diamond Mine, Australia- DEM

A well collated and structured data base integrated into a powerful GIS project can be used to collect and create valuable data for the planning and exploration program for:

1. The advantage of creating large scale area maps which allows them to examine in single scenes or in mosaics the geological portrayal of Earth on a regional basis.
2. The ability to analyze multispectral bands quantitatively in terms of numbers permits them to apply special image processing techniques to discern and enhance certain compositional properties of Earth materials.
3. The capability of merging different types of remote sensing products (e.g., reflectance images with radar or with thermal imagery) or combining these with topographic elevation data (DEMs) and with other kinds of information bases (e.g., thematic maps; geophysical measurements and chemical sampling surveys) enables views of existing or planning of proposed mines.
4. Mapping subregional surface geology.
5. Creating field exploration maps with detailed views of access roads.

Remote sensed data and GIS for mineral exploration is a key to management, planning and monitoring programs requiring on accurate information about the land cover in a region. Methods for monitoring vegetation and land change range from intensive field sampling with plot inventories to extensive analysis of remotely sensed data which has proven to be more cost effective for large regions, small site assessment and analysis.