Geobotanic Remote Sensing for Mo deposit exploration in dinhu Mo ore-field, Guangdong, China
Spectrum and image characteristics of poisoned plants.
In visible and near infrared wave band, the reflectivity of poisoned plant is generally higher than that of the normal plant. It is by about 2-4% in blue band, 3-4% in green light band, 2% in red light band and 10-15% in near infrared band. But it is contrary in infrared wave band. The more the poisoned degree of the plants is the larger the difference of their reflectivity is, in comparison to that of plants in normal area. There are some differences in plant reflectivity in Nov. and Jan. which is higher than that in May. In addition, the reflectivity difference between the poisoned and normal plants is obvious in Nov. and Jan.
By means of differential and Cheboshed plynome analyse of spectrum data, the authors found that blue shift commonly exists in the spectrum of the poisoned plants. It is about 40-80A (maximum 180A). after green regrettable indexes (TM4/TM3) analyze, the index of plants in Mo ore field or alteration zone is lower that n that in normal area, showing that the plant luxuriant degree in ore-field is lower than that in normal area and content of chlorophyll is lower.
During transmissivity measurement for the negative film of ground narrow band spectrum, it is best to measure the transmissivity of the film at its blank as a criterion to overcome the effect
Caused by different film type, photographic speed and develop condition. The result shows a regular change. In Nov. their transmissivities are Mo ore-field < alteration zone < normal area. It lowers by about 1-30% in Mo-ore-field. The trnasmissivities of aerial multispectral negative in been carried out for the aerial multispectral image of the MSS red, green and blue bands. The composite film in Mo ore-field emerges a normal brown-drab and that in the normal area is yellow brown. The grey rang of the positive film in Dec., 1989 is Mo ore-field < alteration zone band, then, the KL change is performed for the composite is also done for the TM CCT 5,4 and 2/3 band, then the KL change is performed for the composite image. In Mo ore-field it appears brown-drab with half ring like, but that in normal area is yellow-brown.
The relative analyses between the Mo contents in rock, soil and plants, plant blade pigment and moisture, the spectrum characteristics of plants and image feature (ground narrow band spectrum photo aerospace) indicates that there is a good relativity. It is know form these facts that grey range of TM is mainly restricted by Mo content in soil and blade; secondly by the blade pigment and moisture of the plants. In summary, the high Mo content in soil resulting from high Mo content in rock leads to plants being poisoned and making a change of chlorophyll content, structure, moisture of the blade. These ill effect on the plans spectrum reflectivity. The anormal reflection result in appearance of anormal color in the aerial multispectral flaes color composite image and Mo ore-field.
Conclusions
The authors have applicated the principle and method mentioned above to search for Au-deposit in Yexi, Haina region and 5 prospective and 2 target for Au have been found. The remarkable social and economical are achieved.
