General situation and metallogenic regularity of silver deposits in Hunan Province

This paper is the result of mineral exploration engineering.

Objective Silver is an indispensable material for modern national defense and cutting-edge science and technology. It is also one of the precious metals used by the people to decorate and beautify their lives.

Methods This paper systematically collected the reserves and distribution of silver deposits in Hunan province. Based on the systematic sorting out of 93 silver deposits in Hunan province, we comprehensively analyze the genetic types and main prediction types of silver deposits in Hunan, and the metallogenic control factors such as strata, structure, magmatic rocks, geochemical anomalies and heavy sand anomalies. Furthermore, the temporal and spatial distribution law of silver deposits in Hunan is also summarized.

Results By 2018, 93 silver deposits were discovered in Hunan province, with a total of 15, 500 tons of resources identified. The identified resources in Hunan accounted for 4.71% of the silver deposits in China. Chenzhou, Hengyang and Yongzhou accounted for 89.40% of the total identified resources in Hunan. Silver is mainly associated with lead, zinc, gold, copper and tungsten, with associated deposits as the main ones, paragenetic deposits and main deposits as the auxiliary ones. These deposits can be divided into six genetic types: skarn type and magmatic hydrothermal type formed by magmatism, epithermal medium- low temperature (MVT Mississippi Valley) type formed by orebearing fluid, mechanical sedimentation (sandstone) type and chemical sedimentation (shale) type formed by sedimentation, and prediction type formed by supergene weathering. Among them, skarn type, magmatic hydrothermal type and epithermal mediumlow temperature type are the main genetic types and prediction types. The distribution map of main prediction types of silver deposits in Hunan is compiled.

Conclusions Four metallogenic epochs are divided into Caledonian, Indosinian, Yanshanian and Himalayan, and Yanshanian is the main metallogenic epoch. In space, silver mines are distributed all over the Hunan province except from Dongting Lake, mainly distributed in the east of Yueyang—Shaoyang line. The resource reserves are mainly distributed in Qibaoshan, Shuikoushan, Qianlishan, Pingbao and Tongshanling. 23 ore concentration areas are divided, subdivided into 7 metallogenic series and 8 subseries. The distribution map of silver ore concentration areas in Hunan province are compiled.