Based on systematic sampling and analysis along the vertical profiles of two skarn (diopside-vesuvianite skarn and

fluorite-diopside skarn) eluvial weathering crusts on the exocontact zone of the granite in the Cuomolong tin-polymetallic ore

district with an environment of high mountain and sparse bush meadow, the authors detected the supergene activity sequence of the

elements in the skarn eluvial weathering crust of the high and cold lake area and investigated their common and specific supergene

geochemical characteristics as well as the major ore-controlling factors. CaO and F have been drastically leached out, whereas K

2O, Na2O, SiO2, P2O5, Sr and TFe are obviously accumulated. Bi, Cu and As, which are very high in parent rocks, have been

leached out in most weathering crusts. TFe has been leached out from organic-rich weathering crusts and separated out from organic-

low weathering crusts through oxidation. Al2O3, TiO2, Sn and Be are very active in the supergene zone, and Sn has been

strongly leached out. Al2O3, MgO, Zn, B and Hg have been either leached out or accumulated, assuming different supergene

behaviors. Ag and Mo, which are abundant in parent rocks, show much less activity capacity in the organiclow overlying eluvial

weathering crust than in the organic-high overlying eluvial weathering crust.