Analysis on Geological Characteristics and Ore-controlling Factors of Silurian Gold Mine in South Qinling the Xunyang Lanmugou Area

Xunyang Lanmugou area is in the eastern section of gold and polymetallic metallogenic belt of southern Qinling orogenic belt. After years of gold exploration in Lower Silurian series of this area, some prospecting breakthroughs has been made by having discovered and measured the Lanmugou gold deposit. Previous studies mainly focused on the geological feature, mineral deposit genesis and ore-controlling factors of the gold mine in the metallogenic belt west to Lanmugou area, few researches could be found on the gold mine of Lanmugou area. To solve the practical problems existed in the future prospecting, and on the basis of researches in the past few years, this paper adopts modern orogenic belt theory to study the tectonic settings, stratal, lithological, tectonic and geochemical characteristics of gold mineralization in this area. It is indicated that the Lower Silurian black rock series of second lithologic section is the material source of the gold deposit of this area. South Qinling Indosinian-Yanshanian intracontinental orogeny gave rise to the massive basement decollement and overthrusting of the tectonicslices between giant nappe fault zones, which was the source of dynamics in the formation of gold mine in Lanmugou area; Hehumiao ductile shear zone is the most important ore-controlling factor in the enrichment and metallization of gold mine in the Lanmugou area. Mylonitic quartz biotite schist overlying onto black mica alteration, quartz alteration, pyrite alteration and limonite alteration is the major sign of this ductile shear zone.