Spectral Wizard Allows Mine Operators to Detect Copper Deposits
Anonym
Customer Challenge
GIS Specialists at the Sensores Remotos & GIS (SRGIS) in Santiago, Chile needed to find copper deposits in the Chuquicamata mine by using spectral signatures.
Solution Achieved
The Chuquicamata mine is the biggest porphyry copper deposit in the world. Investigators at SRGIS knew that the West Fault area had limited mineralization and sterile rock,yet to the east of the fault, they determined that there was copper mineralization. To further determine the viability of the mine, they developed a process to study the spectral responses in ASTER imagery of the area.
During the investigation, the team used ENVI® from beginning to end of their image workflow. Since ENVI supports a wide variety of multispectral and hyperspectral data types, they were able to easily open the ASTER images in their original format and view them directly from within ENVI. Next, the images were geocoded by creating vectors, and effectively isolating ROIs (regions of interest). Different members of the investigative team used a variety of ENVI capabilities. Some team members employed advanced spectral sharpening tools to resample 30m SWIR pixel images to 15m pixel sixe in order to work with VNIR (Visible Near InfraRed - 15m original size) and SWIR (Shoer Wave InfraRed). Once images were geocoded and sharpened, the team executed the automated spectral wizard, which they created to find endmembers in the image. Once endmembers were identified, the user could generate a classified image, where the unique elements are identified and color coded to show where they appear in the image. From those results, they employed ENVI's post classification tools to create images with only endmember spectra information and all other information was masked. They then overlay the classified image with vectorial infromation of faults, grids, and annotations. Finally, the wizard would plot selected endmembers by autmatically invoking ENVI's built in spectral libraries,creating a final map with intuitive results. The map also allowed them to identify the the easter endmember in the images, an argillic alteration that is predominate in rocks with mineralization. Alteration minerals are minerals that are typically found near another mineral, so identifying their presence indicates that the sought after mineral is in close proximity.
The success of the projecet was largely dependent upon the Automated Spectral Wizard, which allowed the team to identify endmembers, make a classification image of the endmembers, mask a region of interest and directly identify unique lithologic types. Says SRGIS ENVI user Jose Manuel Lattues, "By overlaying a vectorial file of faults and lineaments in the district, we could see that the calssification endmember contact matched perfectly with the "West Fault" trace in the mine. This tool was really powerful and precise to detect lithologic types."
Key Benefits
- Using ENVI, SRGIS can now detect spectral signatures in mining areas in order to find concentrations of copper.
- By using ENVI's built-in capabilities, the team was able to create a useful, powerful tool to suit their needs.
- The alternative to using ENVI in mining applications is extensive fieldwork to find, test and evaluate minerals and rocks.