The application of remote sensing to geobotanical exploration for metal sulfides: ECON

This experiment was developed to test the utility of remote sensing for geobotanical ex-ploration. The experiment involved examining vegetation over mineralized and nonminer-alized sites in the Mineral sulfide district, located near Mineral, Virginia, in the Piedmont physiographic province. The mineralized zones are representative both geometrically and genetically of other mineralized portions of the central Piedmont. $ulfides of Pb, Zn, and Cu are the dominant economic minerals. At each test site, 16 oak trees on a 4 X 4 grid, were sampled monthly during the growing season. Sampling consisted of measuring reflectance from leaves using a portable radiometer followed by analyzing the leaves for concentrations of trace metals and nutrients. Soil samples from the A horizon taken at the base of each tree were analyzed for similar elements. Results indicated that mineralization was detected in the portions of the electromagnetic spectrum currently widely used for measuring chlorophyll content and leaf water absorption. Further, it was the variation in the concentration of trace metals in the soil, particularly Pb and Cu, that was found to be associated with leaf reflectance. Thirdly, differences in the spectrum between mineralized and nonmineralized sites were most pronounced iust prior to the onset of visual leaf senescence