Ore Deposit Models and Their Remote Sensing Characteristics

ABSTRACT
Ore deposit models are fundamental to mineral exploration
strategies, and the size of deposits as well as the dimensions and
characteristics of detectable features help define spectral and spatial
resolution requirements for remote sensing. Remote sensing instruments,
engineered for high spatial and spectral resolutions, can yield
detailed data for mineral exploration and geologic mapping applications.
Effective application of specialized sensors requires thoughtful
data selection and image processing specifications from the user.
The information available from hyperspectral short-wave infrared
(SWIR) sensors with <50 nm bandpasses and mid-thermal infrared (TIR) instruments with 200 nm bandpasses and 4 m spatial resolutions can expedite geologic mapping and provide guides to mineralization. Hyperspectral instruments are capable of identifying silicification, differentiating silicate alteration types, discriminating compositional and crystallinity variations within some mineral species, detecting mineralogical variations within igneous and metamorphic complexes, and mapping facies changes within sedimentary units. Variations among ore deposit types influence choice of both remote sensing data and image processing techniques. The precious metal, porphyry copper/molybdenum, volcanogenic massive sulfide, sedimentary exhalative, Olympic Dam, Broken Hill, Mississippi Valley, and stratiform copper deposits comprise the most important base and precious metal ore deposit types. The spectral ranges and spatial resolutions required to detect many of the distinctive physical features of these important hydrothermal deposits are outlined. Spatial resolution requirements are estimated to vary from about 30 to 2 m, depending on project scale, size and spectral contrast of detectable features, and areal extent of exposure. Based on the spectral characteristics and dimensions of the geologic features that define the various ore deposit models, a geologist can design a remote sensing strategy that is consistent with an exploration or development plan.