| The Dongping gold is founded at the northern margin of the western part of the North China Craton in the 1980s which is located at the inner contact zone of the alkaline-partial alkaline syenite complex and is the large type of medium-high temperature hydrothermal quartz veins, K-feldspar altered rock gold deposit. The top of deposit is the type of quartz, but the bottom is K-feldspar altered rock. The range of metallogenic temperature are 263～342℃. Mineralizing fluid is the mixed hydrothermal solution of atmospheric precipitation and anatectic fluid. The type of ore is poor sulphide but rich telluride. This paper utilize reflection microscope, scanning electron microscope, electron probe microanalysis, X-ray diffractometry, major and trace element analysis to detailedly study telluride minerals spatial distribution pattern, association feature, composition, phase and element geochemical feature, which discuss the condition of generating and the relation of gold mineraliztion in the Dongping gold deposit. The main research results are as follows.1. The metal minerals are pyrite, chalcopyrite, galena, magnetite, hematite, altaite, petzite, calaverite, native gold, tellurobismuthite and tetradymite in Dongping gold deposit. The main mineral assemblage is pyrite-chalcopyrite-altaite-petzitecalaverite-native gold. The type and content of telluride minerals decrease spatially from top to bottom in ore-body, and the fineness of native gold is similarly. Mineral assemblage change obviously in lateral ore-body, and when telluride mineral have appeared, Au beginning enriched. The variation range of the content of Au and Ag are negative correlation.2. All of the chondrite-normalized REE patterns of ore samples indicating that metallogenic material mainly derived from the syenit ore-bearing formation. A large number of rare earth elements carryover occurred in the process of silicified alteration. The reducing LREE/HREE ratio reflects the relative loss of light rare earth elements in hydrothermal activity. The primitive mantle-normalized incompatible elemental diagram for ores is similar to that for syenits, indicating metallogenic material inherited characteristics of the syenite.3. Variation range of the content of Au and Ag, Te are positive correlation in the ore-body of K-feldspar altered rock. There four assemble elements of Cr, Ni, Mo; W, Hg, Ag, Au, Te; Zn, As, Pb; Sb, Co, Bi, Cu, Sn have much better correlation. The assemble elements of Au, Ag, Te and Cu, Zn, As, Mo, Sn, Sb, Hg indicate the primary halo of deposit importantly.4. Geochemical parameter occur three transition in axial trend of ore-body, which respectively indicate that the different stage ore-body overprint, and the transition of bottom indicate the deep ore-body extending. All zonality sequence appears that the front halo and the rear halo coexist, reverse zoning, this indicating the favourable prospect of mineralzition in deep south-west block of No.70 ore-body.5. Process of evolution of mineralizing fluid system is that Te associated with Pb producing altaite preferentially, and follow that Te combined with Au and Ag producing a large number of petzite. When Ag was consumed enormously and the condition of physical-chemical changed that Te beginning combined with Au generating calaverite. Finally, Te was consumed enormously producing complicated telluride minerals, which lead to the residual Au, Ag precipitating and generating native gold in mineralizing fluid. In the condition of the higher fugacity of Te produce enormous telluride minerals, and the native gold have much higher fineness. |
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