M. Lorraine Tighe, PhD
Dr. Tighe has a Ph.D. in Earth Sciences, a graduate degree in Remote Sensing and GIS, and a B.Sc. in Physics and Geology. Dr. Tighe has delivered lectures ranging from a half day workshop to a 4 week training program to over 2000 participants in USA, Canada, Jamaica, Brazil, Ecuador, Honduras, … More »
Seeing through the trees
September 13th, 2013 by M. Lorraine Tighe, PhD
Successful mining exploration relies heavily on the accuracy of the geology map layer that depicts the spatial distribution of geologic units and structure. Often times, however, existing geologic maps vary in quality and accuracy due to differences in purpose of mapping, scale or level of details, inconsistency in nomenclatures, and types of map projection/registration. Conventional mapping methods of bringing existing geologic maps to the desired quality level or standard will entail a large amount of time and effort, and consequently will also drastically slow down mineral exploration. The creation of digital geology maps (map components: topography, structure, and lithology) from the desktop using interferometric syntehtic aperture radar (IFSAR or InSAR) provides a cost effective method, espeically in remote dense vegetated areas.
Surficial geology and inferred stratigraphy can be mapped using IFSAR derived elevation data (e.g. NEXTMap® DSM/DTM and ASTRIUM Tandem-X DSM) combined with SAR imagery (e.g. NEXTMap ORI, TerraSAR-X). Unconsolidated sediments are often manifested as topographic relief. Radar is sensitive to changes in moisture and roughness, which results in contrasting backscatter between different soil types and thus different vegetation cover. Topographic patterns displayed in perspective views of SAR DEM data, represented as shaded relief topography, make geologic features “pop” out, allowing for 1:10,000 to 100,000 scales regional and reconnaissance geologic mapping. Contour generation from the IFSAR DEMs, coupled with the rich texture offered in the SAR imagery, provide a medium to map drainage patterns. The drainage patterns, SAR texture, and geologic structure yield important clues about lithology to round out the last component of a geologic map. These geologic geospatial layers feed reconnaissance mapping and mineral exploration, without stepping into the field.
Image 1: A perspective view of NEXTMap World30m DSM data in central,Africa demonstrates regional scale geologic structure.
Image 2: NEXTMap data derived contours and drinage patterns in are key components needed to interpret geologic structure and lithology. Data location: Sulewasi Indonesia.
Category: Geospatial Information