The Geological Features And Genesis Of The Jiashengpan Lead-Zinc Deposit In Inner Mongolia, China

The Jiashengpan lead-zinc-sulfur deposit is located in Langshan-Zhaertaishan mineralization belt in the western part of northern margin of North China Platform. The ore bodies occur in the third order fault-basins in the aulacogen of passive continental margin of North China Platform. In this article we study the characteristics of geology, isotope geochemistry and fluid inclusion geochemistry. Main conclusions as following:(1) The deposit forms in the extensional tectonic environment and occurs in Mesoproterozoic Zhaertaishan Group. The ore bodies are mainly layered and are composed of layered, conglomeratic and disseminated ores. The deposit is obviously stratabound and controlled by rock lithology. The synchronous fault is one of the main ore-controlling factors.(2) The characteristics of isotope geochemistry indicate that the sedimentary environment is mainly a marine reduction under anaerobic environment and the ores development exhalative hydrothermal-sedimentary mineralization. The sulfur isotopes of deposit are being high-value without the characteristics of mantle-derived sulfur and derive from sea sulphate. Volcanic magma activity does not participate in the process of ore-forming. The most mineralizing materials of deposit are derived from the old basement strata during the main ore-forming period. The others are mainly derived from the late hydrothermal event and are under the influence of the Hercynian granite to the north of ore bodies.(3) The characteristics of fluid inclusion petrography, micro temperature of fluid inclusions and LRM indicate that fluid inclusion of deposit is H2O-N2-CO2-SO2-CH4 system with the characteristics of low-medium temperature, weak alkaline and strong reducibility and contains organic components. Combining the characteristics of hydrogen and oxygen isotope, we can infer that fluid inclusion is complex with the mixture of seawater, construction-water and organic-water.(4) The Hercynian granite intrusions cause the enrichment and modification of ore body. Thermodynamic contact metamorphism develops near the contact zone. The re-crystallization of some mineral develops. However, the transformation is limited to the activation, migration and redistribution of the early minerals without new materials. Locally, it changes the occurrence of ore bodies.In summary, The Jiashengpan deposit has significant features of sedimentary exhalative deposit (SEDEX). Compared to the other hydrothermal sedimentary deposits, there is no volcanic activity during metallogenic period in the Jiashengpan deposit and its late reformation is weak relatively.