The metallogenic structural system and metallogenic regularity of the Huayuan lead-zinc orefield in western Hunan Province

Typical stratabound lead-zinc deposits are developed in the Huayuan lead-zinc orefield, western Hunan Province, with great prospecting potential. Many researchers have systematically studied the geological characteristics of the deposits in this area, but there are different opinions on the genesis of the deposits and ore-controlling factors. There are four main viewpoints: Mississippi Valley type, sedimentary type, post-diagenetic reformation type and basin-source low-temperature hydrothermal type. In this paper, the relationship between structure and mineralization was analyzed by means of structural measurement and analysis and palaeostress field recovery, and the tectonic stress was divided into three stages: the principal compressive stress of premetallogenetic structure is in approximately vertical direction to layers, and the principal compressive stress of metallogenic period is in NW-NNW direction, the principal compressive stress after mineralization is in NE-NNE direction. The Limei gentle anticline and Yutang anticline were formed in the orefield during the metallogenic period, and various ore-bearing breccias and fracture systems were formed in the algal limestone layer. These fractures provided a rich reaction interface for the chemical reaction between the hydrothermal solution and the organic matter in algal limestone, which seems to be the main reason for the enrichment of the lead-zinc ore solution. Post-metallogenetic structure was formed during Yanshanian period. A large strike-slip normal fault zone was formed under NNE-SSW compressional stress, which destroyed and reworked the ore-bearing fold during the Caledonian period.