”In my opinion, before any exploration or mining, one needs a good understanding of the geology and the only way to do that is by proper geological mapping. Mapping gives you the foundation of the entire structure.” – Sodhie B Naiker.
A geological map showcases geological features such as rocks or geologic strata revealed by colour or symbols to indicate where they are on the surface.
Kai Batla Minerals Consultants spoke to Mining & Mineral Product Review (MMPR) and explained the two different levels geological mapping needs to take place in the mining industry: underground and on ground surface. For the latter, traditional mapping methods include aerial photography and ‘walking the ground’, doing it manually.
Modern techniques for surface level mapping includes using satellite data and relying on different bandwidths to enhance different signatures. With this type of technology, mapping results produce different colours with similar attributes. However, rock variations can not be discriminated from satellite information. Geologists then manually check to verify rock types and what else is available in the area.
Under ground, geologists use photographs to capture what’s available underground as satellites cannot be used. Kai Batla’s technical director, Naiker said traditional methods for mapping underground is as simple as using pen and paper as well as tape measures.
Surface mapping is done only once, while underground mapping is frequent. Kai Batla managing director, Avinash Bisnath, says, “Underground mapping should be done daily,” however, his colleague, Naiker, points out that this depends on available resources. If it’s not completed daily, it should be done at least every two days.
The industry is evolving
CK Aerial Surveys sales manager, Sam Houniet, said technology used for geological mapping is evolving all the time. Currently, companies are relying on Light Detection and Ranging (LIDAR). The technology uses lasers to determine the distance to an object or surface. A huge advantage with this technology is it has greater abilities to reflect images, making the images more visible. Houniet explains, “LIDAR is able to penetrate through plant growth to make sure they really get to ground point.”
However, LIDAR is not the be all end all; Geo mapping techniques compliment each other. Kai Batla experts explain there’s always room for human error with this job. But if different techniques are used, it’s easier to spot where the mistakes have been made.
Some techniques used vastly in the industry include:
Aerial photography: taking photographs of the ground from an elevated position using fixed-wing aircraft, helicopters, balloons, blimps and dirigibles, rockets, kites, poles, parachutes, and vehicle mounted poles. Oblique photographs are taken at an angle: if taken from a low angle such as from an–aircraft, they are called low oblique, and photographs taken from a high angle are called high or steep oblique. Vertical photographs are taken straight down and used for photogrammetry and image interpretation.
Point cloud: is combined with Inertial Measurement Unit (IMU) and Global Positioning System (GPS) data to ensure every point in the cloud is within 10cm of accuracy
Photography: high resolution ortho-rectified photos are overlaid on the data to create high detailed maps.
Contours: a contour line joins points of equal elevation above sea level. A contour map is illustrated with contour lines. The line intervals of a contour map show the difference in elevation between successive contour lines.
Digital terrain model (DTM): is created by digitally removing all of the cultural features inherent to a Digital Surface Models (DSM) by exposing the underlying terrain. mmpr