TY - JOUR
T1 - Discrimination of low-grade magnetite ores using remote sensing techniques
AU - Rajendran, S.
AU - Thirunavukkaraasu, A.
AU - Poovalingaganesh, B.
AU - Kumar, K. Vinod
AU - Bhaskaran, G.
N1 - Funding Information:
The authors are extremely thankful to ISRO, Bangalore for sanctioning to first author the ISRO-RESPOND Project "ELGIORD" and providing financial support to carry out this study. Our thanks are to T. Natarajan, Director, Institute of Remote Sensing, Anna University, Chennai for his encouragement and providing data facility towards this work. We are thankful to the Professor and Head, Department of Geology, Madras University for providing facility for chemical analyses of samples. Also, we are thankful to staff-in charge, of the CSIL Laboratory, Annamalai University for providing FTIR analytical data.
PY - 2007/6
Y1 - 2007/6
N2 - The remote sensing community in geology is widely using the Multispectral Landsat Thematic Mapper (TM) data which has a wider choice of spectral bands (six between 0.45 and 2.35 &mgr;m, plus a thermal infrared channel 10.4-12.5 &mgr;m). These were evaluated for low-grade magnetite ores mapping over the high-grade granulite region of Kanjamalai area of Tamil Nadu state, India. The Fourier Transform Infrared (FTIR) spectroscopy data (0.4-4.0 &mgr;m) for powders of the magnetite ores exposed with granulite rock and published spectral reflectance data were used as guides in selecting TM band reflectance ratios, which maximize discrimination of magnetite ores on the basis of their respective mineralogies. The study shows that the weathering mineralogy of magnetite ores causes absorption features in their reflectance spectra which are particularly characteristic of the near infrared. Comparison of TM data with field and petrographic observations shows the presence of magnetite and aluminosilicate minerals & show strong absorption at 0.7-1 &mgr;m wavelength spectral region & increase in the product of two TM band ratios: band 5 (1.55-1.75 &mgr;m) to band 4 (0.76-0.9 &mgr;m) and band 3 (0.63-0.69 &mgr;m) to band 4 (0.76-0.9 &mgr;m). Various computer image enhancement and data extraction techniques such as interactive digital image classification techniques using color compositing stretched ratio, maximum likelihood and thresholding statistical approaches using Landsat TM data are used to map the low-grade magnetite ores of the granulite region. The field traverses and local verification enhanced to map the other rock types namely granulites and gneisses of the study area.
AB - The remote sensing community in geology is widely using the Multispectral Landsat Thematic Mapper (TM) data which has a wider choice of spectral bands (six between 0.45 and 2.35 &mgr;m, plus a thermal infrared channel 10.4-12.5 &mgr;m). These were evaluated for low-grade magnetite ores mapping over the high-grade granulite region of Kanjamalai area of Tamil Nadu state, India. The Fourier Transform Infrared (FTIR) spectroscopy data (0.4-4.0 &mgr;m) for powders of the magnetite ores exposed with granulite rock and published spectral reflectance data were used as guides in selecting TM band reflectance ratios, which maximize discrimination of magnetite ores on the basis of their respective mineralogies. The study shows that the weathering mineralogy of magnetite ores causes absorption features in their reflectance spectra which are particularly characteristic of the near infrared. Comparison of TM data with field and petrographic observations shows the presence of magnetite and aluminosilicate minerals & show strong absorption at 0.7-1 &mgr;m wavelength spectral region & increase in the product of two TM band ratios: band 5 (1.55-1.75 &mgr;m) to band 4 (0.76-0.9 &mgr;m) and band 3 (0.63-0.69 &mgr;m) to band 4 (0.76-0.9 &mgr;m). Various computer image enhancement and data extraction techniques such as interactive digital image classification techniques using color compositing stretched ratio, maximum likelihood and thresholding statistical approaches using Landsat TM data are used to map the low-grade magnetite ores of the granulite region. The field traverses and local verification enhanced to map the other rock types namely granulites and gneisses of the study area.
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U2 - 10.1007/BF02990779
DO - 10.1007/BF02990779
M3 - Article
AN - SCOPUS:70350123272
SN - 0255-660X
VL - 35
SP - 153
EP - 162
JO - Journal of the Indian Society of Remote Sensing
JF - Journal of the Indian Society of Remote Sensing
IS - 2
ER -