Distribution characteristics of mineral deposits in Yunnan, China

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The availability of GPS (Global Positioning System) has been examined in three areas. The first is a fixed point. Measured values are scattered within 100 m from the true position. The second area was selected because topographic maps (1/25000) are published. Each GPS value was compared with the position given from a topographic map. The deviation is within 300 m. The third area is Yunnan Province, southwestern China, where foreigners are prohibited to use topographic maps. The accuracy was checked by the reproducibility. When 4 satellites were found in wide areas, values were scattered in a circle whose diameter was 200 m. When 4 satellites were found in narrow areas, the diameter was 500 m. When only 3 satellites were found, the diameter was 1000 m. The result suggests that the GPS can provide location data with the accuracy enough to regional geoscience discussions.An ore value-tonnage diagram has been proposed for assessing mineral resources. Diagrams of W+Mo, and Pb+Zn deposits show a good linearity between ore value and logarithms of cumulative ore tonnage. Diagrams of the massive sulfide, orthomagmatic, placer, porphyry, replacement, and stratabound types are also linear. It is assumed, therefore, that deposits of each of these commodities and these types belong to a single population. In contrast, the ore value-tonnage relations of all the deposits analyzed here is approximated by the combination of two exponential functions. The same feature is seen for deposits of the Cu+W+Mo, Cu+Pb+Zn, and Au+Ag commodities, and of the vein and unconformity-related types. This suggests that deposits belonging to each of such categories are divided into the high and low value groups.