Research on sedimentary tectonic metallogenic of Hongyanxi area in the northwest Hunan

Hongyanxi area in the northwest of Hunan is on the south central of Xiangxi-Exi polymetallic metallogenic belt and it belongs to the southeast of upper Yangtze region. The major sedimentary formations are from Cambrian to Silurian and there are many Pb-Zn deposits along Hongyanxi fracture with northeast strike. These Pb-Zn deposits are in the limestone of Tongzi Formation and Honghuayuan Formation of Ordovician period. Firstly, this paper used stratum, rock and tectonic feature to characterize stratum, rock and tectonic feature about the Pb-Zn mine, found out the metallogenic geological background and qualification, and summarized the metallogenic law. This study also analyzed the forming mechanisms of the storm deposit in Tongzi Formation, bioherm limestone in Honghuayuan Formation, crazing construction in Baota Formation and turbidities of far source in Xintan Formation. So the model of Ordovician-Silurian sedimentary tectonic evolution was built, which was from passive continental margin (extensional system) to foreland basin (compressional system). Secondly, this paper investigates the connection between fracture and Pb-Zn deposits, and found out the faults strike to northeast and north-north-east are the ore-transmission structures, and those pointing to northwest are ore-hosting structures. Also the form of metallogenic environment of Pb-Zn deposit from aspect of fluid inclusion was discussed. The results show the mineralizing hydrothemal is similar to the hot brine in the basin, which is originally coming from interlayer and meteoric water. Finally, the Pb-Zn metallogenic model was built.