The geological features and genetic pattern of Te-Au deposit related to porphyry in North Qilian Mts

Chelugou gold deposit is the first Te-Bi-Au deposit related to porphyry found in North Qilian orogenic belt. The gold deposit forms in post-volcanic inter mediat e-acidic intrusive rocks of island arc, and directly occurs in hypabyssal-ultrahy pabyssal dacite-porphyry. The diagenetic age is 427.7±4.5 Ma, and the metallogenetic age is 350～410 Ma. The research indicates that the deposit could be produced by mixing with magmatic hydrothermal and at mospheric water. Af termagma positioning and solidifying, the magmatic hydrothermal differentiated from deep magma chamber (source) , riching in metallo genic elements of Au, Te, Cu and volatile components of CO₂, SO₂, H₂O, ascends through tectonic fissures, mixed with at mospheric water, and constantly extracts ore-forming matter from solidified dacite-porphyry and adjoining rocks. Generally, the metallogenic fluid is a kind of low-temperature, less-vapor-phase, medium-high-density, higher-salinity H₂O-CO₂-NaCl (KCl) system. The genetic type of the depositis a hypabyssal epithermal Te-Au depositre-lated to porphyry.