Mineralization Model of Rich Ge-Ag-Bearing Zn-Pb Polymetallic Deposit Concentrated District in Northeastern Yunnan, China

The deposit concentrated district of germanium-silver-bearing lead-zinc polymetallic ore deposits in northeastern Yunnan is an important component of the Sichuan-Yunnan-Guizhou lead-zinc polymetallic domain in the southwestern margin of the Yangtze block. The deposits are characterized by very high grade of the ore, more associated minerals such as germanium and silver, deep extension of ore bodies, large scales of the ore deposits, and great economic value. The deposits of this kind reflect a typical ore-forming environment, which is different from known lead-zinc deposit types discovered in both China and abroad, such as Mississippi Valley Type (MVT), Volcanic Hosted Massive Sulfide Type (VHMS), and Hydrothermal Sedimentation Type (SEDEX). Therefore, this study proposed that this kind of deposits is representative of a new Pb-Zn deposit type-Huize type (HZT). The formation of these deposits was related to tectonic regime transformation from late Hercynian tectonic extension to Indosinian orogenic extrusion, and this was responsible for the establishment of a new model - structural fluid mineralization model. The formation of such ore deposits has gone through three phases: A) trusting structure and large-scale fluid migration; B) fluid penetration and gas differentiated from liquid; C) fluid unloading and by gravity differentiation. This model can be used to interpret the mineralizing mechanism of the lead-zinc deposits occurring in the ore deposit concentration district of northeastern Yunnan. This is undoubtedly of great importance in studying Sichuan-Yunnan-Guizhou lead-zinc polymetallic metallogenic field, and in prediction, exploration and evaluation of concealed ore localization in the deep parts and external district of the type deposits.