Multi-frequency and Multi-polarization Radar for Geological Applications

摘要

As part of the SIR-C/X-SAR and the GlobeSAR Programs, Chinese radar remote sensing project entitled "Geological applications using multi-source SAR data" has been undertaken since 1993. SIR-C/X-SAR and GlobeSAR have imaging capabilities of L, C, and X bands with quad-polarization and C, X bands with quad-polarization respectively, In 1993, GlobeSAR was flown over Chinese Guangdong radar test area, and obtained dual-bands, multi-polarization radar data. In 1994, SIR-C/X-SAR imaged test sites of Chinese Xinjiang, Inner-Mongolia and Guangdong, and obtained three bands, multi-polarization data. The differences in geometric and physical characteristics of the surface of geological bodies constitute the different radar responses of corresponding radar bands to the surface roughness, and the responses of differences in depolarization capability to the polarization combinations, which result in characteristic response of geological bodies to the radar images. Geological information are enriched to a great extent on radar images. Compared with single band and single polarization radar, the multi-band and multi-polarization radar show an important superiority. In the radar test areas of Chinese Xinjiang and Inner-Mongolia where climate is very dry, vegetation are sparsely distributed and bedrocks are widely exposed, radar can directly detect the surface nature of geological bodies. An experimental study of SIR-C penetration was carried out in Inner Mongolia by burying corner reflectors into dry sands, Using multi-bands, multi-polarization SAR can identify unknown volcano structure, reveals coarse grain texture and distinct lithological phase of granite bodies, and provides new information for large scale gold-bearing structural zones. In the test site of Chinese Guangdong where is in subtropical zone, vegetation are well developed and outcrop rocks are rarely seen. Multi-band, multi-polarization radar disclose the geological phenomena under the cover of vegetation. The strata which is not easily identified are shown on the synthetic aperture radar (SAR) images. Faults were also identified and the displacement of strike-slip fault was measured. A large gold-bearing mylonite belt was analyzed, and the scope of the extending areas was pointed out according to the texture features revealed by SAR.