Applying Hyperspectral Remote Sensing Techniques for the Detection of Hydrothermal Alteration Zones and Gossans in Northern Canada

• Author / Creator

  Laakso, Kati S.

• This thesis is composed of three chapters assessing the following specific goals: 1) To evaluate the potential of airborne hyperspectral remote sensing data and techniques to delineate the hydrothermal alteration zones of volcanogenic massive sulfide (VMS) systems in areas of abundant lichens on rock outcrops; 2) To assess the potential of hyperspectral remote sensing data and techniques to unmask the hydrothermal alteration intensity variation of VMS systems; 3) To investigate the effect of the rock substrates and lichens on the spectral properties of gossans in the visible-near infrared wavelength region (VNIR, 400-1300 nm); 4) To evaluate the potential of hyperspectral remote sensing data to unmask the mineralogical properties of the rock substrates of gossans in the short-wave infrared wavelength region (SWIR, 1300-2500 nm). First, in Chapter two airborne and ground hyperspectral data from an economically important Izok Lake VMS deposit (Nunavut, northern Canada) are used to test the ability to unmask hydrothermal alteration zones by remote sensing in an area of abundant low-growing ground cover. The results suggest that these zones can be delineated by hyperspectral airborne remote sensing means even if the dense ground cover necessitates the masking out of many pixels in the scene. In Chapter three, the applicability of hyperspectral ground and laboratory remote sensing data are used to estimate the hydrothermal alteration intensity variation of the Izok Lake deposit. The results suggest that there are statistically significant relationships between the spectral properties of the phyllosilicate minerals (white micas and biotite/chlorite) and alteration indices (the Ishikawa and chlorite-carbonate-pyrite index). These relationships can be exploited to investigate the large scale hydrothermal intensity variation of VMS deposits. Furthermore, the investigations of Chapters two and three suggest that biotite/chlorite can provide a stronger vector toward the massive sulfide lenses of the Izok Lake deposit than white micas. Finally, Chapter four discusses the optical thickness properties of gossans, and the effects of lichens and rock substrates on their spectral properties. These phenomena were investigated by means of laboratory and airborne hyperspectral remote sensing data from the Cape Smith Belt in northern Canada. The results indicate that some gossans are optically thin, enabling the transmission of light into the rock substrate. The implications are twofold. First, the rock substrates can influence the spectral shape of the iron oxide minerals, the main constituents of gossans, in the VNIR wavelength region. Second, the mineralogical properties of the host rock substrates of optically thin gossans can be detected by remote sensing means. This finding can be used for mineral exploration in areas of a known link between specific rock types and ore deposits. Also, our investigation in the Cape Smith Belt suggests that spectral mixing between gossans and lichens can influence the spectral shape of gossans in the VNIR wavelength region. As in case of spectral mixing between gossans and their rock substrates, understanding the effects of such mixing is important because it can affect the ability to characterize the mineralogical properties of gossans by remote sensing. My thesis addresses issues that are critical to the advancement of hyperspectral remote sensing techniques for mineral exploration in the subarctic and Arctic. The investigations discussed in my thesis contribute to the understanding of the applicability of hyperspectral airborne, ground and laboratory remote sensing datasets and techniques to unmask potential ore deposits in northern areas.

• Subjects / Keywords

  • Airborne remote sensing
  • Volcanogenic massive sulfide deposit
  • Hyperspectral
  • Hydrothermal alteration intensity
  • Alteration index
  • Gossan
  • VMS
  • Mineral exploration

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3901ZN9G

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.