Abstract:
Fengtai ore concentration area is rich in gold resources, with great achievements and breakthrough from gold deposit detection in recent years. The authors in this paper summarized the metallogenic regularity in Fengtai ore concentration area through analysing and comparing the geological and ore-forming fluids characteristics of typical gold deposits. There are various types of gold mineralization in Fengtai ore concentration area, but properties and sources of ore-forming fluids and materials are unified. The ore-forming fluids with shallow metallogenic depth were mainly from atmospheric precipitation, while those with deep metallogenic depth were mainly from metamorphic fluid and magmatic hydrothermal fluid. The metallogenic environment of Pangjiahe gold deposit is medium and low temperature- low salinity- low density- medium hypabyssal, while the metallogenic environment of Baguamiao gold deposit is medium and high temperature-CO
2 rich-medium and high salinity- medium plutonic. Besides, the metallogenic environment of Shuangwang gold deposit is medium and high temperature-CO
2 rich-medium and low salinity-medium and high pressure-medium plutonic. The metamorphic fluid characteristics in these three gold deposits are obvious, with similar characteristics of orogenic gold deposits. The gold mineralization process in the study area was characterized by multi-period and multi-stage. And the gold mineralization was first pre-enriched by Au element in the strata, then mineralized with magmatic hydrothermal fluid, metamorphic hydrothermal fluid, and groundwater caused by the Indosinian (main metallogenic period) tectonic events. At last, the gold mineralization was superimposition reformed and enriched by the hydrothermal fluid during the Yanshanian.