Remote sensing research in biogeochemistry of the Hetai gold deposit, Guangdong Province, China

Abstract

The vegetation has been poisoned by Au in the Hetai gold deposit region, Guangdong Province, China. The Au content in the leaves of plants is up to 269 times higher than that of the abundance, the chlorophyll content is 10–30% lower than that of the vegetation in metamorphic terrains, and 10–20% higher than that in granite terrains. The carotenoid content is 10–44% lower than the background value. The Au content in the chlorophyll is up to 97 times higher than the abundance; the Fe and Mg of the pigment is 60% and 1.4–8.6% of the abundance. The water content in leaves is 10–20% lower than the background value. The temperature of the leaf surface is 8% lower than the background value. Cells of leaves are deformed and broken. The leaf surface shows yellow or dark green spots. Spectral reflectance of the leaf surface is 5–30% higher than the background value; the spectral shape has shifted 5–15 nm to the short wavelength in the 300–800 nm band, and to the long wavelength in the 800–2500 nm band. The greyscale values of the canopy in images from Landsat Thematic (TM) and Airborne Imaging Scanner (AIS) are 10–100% higher than the background value. On Landsat TM and AIS false colour images, plants poisoned by Au display a yellow colour, which distinguishes them from background plants. According to the spectral and image features of Au biogeochemical effects, a gold deposit information system has been constructed, and thus more than 20 gold deposit target areas have been identified rapidly, economically and accurately in Northeast China, Northwest China, South China and the Qinling mountain range in China, which is covered extensively by vegetation.

Acknowledgments

This research was supported in part by the Bureaus of Geology and Mineral Resources and the Nonferrous Metals Exploration companies of Guangdong, Hainan, Heliongjiang, Henan, Shanxi, China, the No. 719 Geological Party of the Guangdong Bureau of Geology and Mineral Resources, the No. 933 Geological Party of the Guangdong Nonferrous Metals Exploration Company, the No. 934 Geological Party of the Hainan Nonferrous Metals Exploration Company, and also received support and guidance from Professors Tuguang Zhi, Ye Lianjun, Chen Guoda, Chen Shupeng, Sun Shu, Quyan Ziyuan and Tong Qinxi. To all the above organizations and individuals sincere thanks are due.