オーストラリア・Rudall地域におけるリモートセンシングによるウラン鉱床胚胎母層の抽出

抄録

Power Reactor and Nuclear Fuel Development Corporation (PNC) has been conducting uranium exploration in the Rudall region, Western Australia, since 1989. The geological setting of this region is similar in age, rock types and structure to the Alligator River region in the Northern Territory, Australia and to the Athabasca region in Saskatchewan, Canada, where are currently the most important uranium province in the world.
The Kintyre uranium deposit is located in this region and hosted in the Lower Proterozoic metasediments. Consequently, it is important to delineate these rocks, especially chlorite schist, for the first stage of uranium exploration in this region.
Landsat Thematic Mapper (TM) data analysis was performed to delineate the Lower Proterozoic metasediments in this region. TM band combinations which were thought to be useful to delineate these rocks were examined on the basis of mineral content and conditions of rock surface of the host rocks in the Kintyre uranium deposit and the inter-band response pattern of each rock type which was distributed in this region. As the result of the examination band ratios band 3/band 1, band 3/b and 5 and band 5/band 7 were selected and combined in blue, green, red respectively to create a ratio color image. Metasediments were shown by yellow green on the ratio color image and apparently discriminated from other rocks. These results were also confirmed by the ground truth.
In order to clarify the reason why metasediments were shown by yellow green on the ratio color image, reflectance spectra of the host rocks in the Kintyre uranium deposit were measured by the IRIS spectroradiometer. It was found that the cause which the host rocks were shown by such distinctive color on the ratio color image was due to the flat pattern of reflectance spectrum from the visible to the short-wavelength-infrared (0.6-1.6 μm).