HyMap - Hyperspectral Mapping - GeoVision beyond the Visible

Most geoscientists are familiar with the colorful LandSat imagery we have been provided with for almost 30 years. These multispectral data sets have allowed us to see the earth in colors not accessible to the human eye and hence allowed discrimination of previous, not distinguishable geological features. Technology has progressed and it is now possible to view the earth not only in a few, but hundreds, of different spectral channels over a wide wavelength range; and to map the surface composition based on the spectral signatures observed. We call that “hyperspectral sensing” and despite some attempts with satellite systems, airborne instruments are leading the way. An Australian designed and built sensor is one of the world’s outstanding performers and has delivered high quality data sets worldwide in over 27 different countries. Applications range from mineral mapping to environmental monitoring, geothermal prospecting to oil seep identification. From small scale targeting to large area mapping, HyMap has demonstrated its usefulness equally to geological surveys, environmental agencies and exploration companies. When trying to convince the classic exploration geophysicist of the usefulness of a detailed mineral map for his exploration lease many seem skeptical and refer to hyperspectral as ‘only’ being a surface tool. However quite often surface mapping can reveal astonishing details about the presence of alteration minerals, their mineral chemistry and spatial distribution. With a high spatial resolution of down to 3m, structures like quartz veins or gossans can easily be identified and can highlight new, previously inaccessible exploration targets. Even in the highly weathered, regolith dominated Australian environment, HyMap has discovered structures and residual anomalies previously unknown to geoscientists, many of which are not present in the standard geological maps of the area. For many exploration managers remote sensing data is still synonymous with large-area overviews rather than detailed, specific information related to an exploration issue. Often the data processing and interpretation skills are not advanced enough to extract the relevant information for the project. However, demonstration projects by CSIRO and Australian state mapping agencies lead the way and create insight into the potential uses of hyperspectral technology. If we can directly send the drill crew to a promising alteration / target / anomaly area and avoid ‘blind’ holes we may actually save money by investing in the right remote sensing technique. Having highly accurate mineral maps may actually allow us to correctly identify the exploration model to be used for a specific Figure 1: HyMap data acquisition.