Case Histories of Orogenic Gold Deposits

Abstract

This review compares genetic parameters of 12 orogenic gold deposits. The set of examples is considered to represent largely the variability of orogenic gold deposit (OGD) characteristics. The data are presented in tables and include following definitive parameters: regional geologic settings, nature of hosts rocks and mineralization, ore controlling structures, ages of host rocks and mineralization and timing of mineralization relative to metamorphism, hydrothermal alteration mineralogy and ore mineral assemblages, isotopic signatures, physical conditions of ore formation and proposed origin of ore fluids aa well as gold reserves, production, and grades. This allows comparison of deposits from different geologic terrains having different ages and formed under different P-T conditions. The data are further discussed before the background of the orogenic gold system and the crustal metamorphic models that provide different scenarios to explain the source of ore fluids. The orogenic gold system model advocates a metal and fluid source external to the terrain in which mineralization occurred, but the model applies only for 3 of the 12 deposits studied. All other deposits formed most likely from a crustal source, which would favor the crustal metamorphic model. However, the formation of hypozonal OGDs cannot be accounted for by the crustal metamorphic model or by the metamorphic devolatilization model. The data identify a set of coherent signatures in OGDs, but there seem to be no unified model for all possible environmental conditions and facets of ore formation and fluid sources, tectonic and lithologic setting, and scale of gold endowment.

The metasedimentary-hosted Nyangoubé gold prospect, northwest Côte d’Ivoire: Geochemical and mineralogical characterization of associated hydrothermal alteration

“…It is explained by the addition or replacement of quartz to the detriment of the minerals existing in the rocks at the contact between fluids and rocks. When hydrothermal fluids carrying dissolved gold react with host rocks, silicification occurs concurrently with gold concentration [ 74 , 75 ]. Gold can be precipitated directly in quartz as a gold-bearing mineral like auriferous pyrite.…”

Development of an Economic Cost Model for Gold and Associated Minerals Using Economic Analysis and Artificial Intelligence Approach

“…It is primarily found in veins and lodes within rocks and ore deposits (Du et al, 2023). As mentioned by Meyer (2023), gold deposits are formed through geological processes such as hydrothermal activity, where hot water carries goldbearing minerals to cooler environments, allowing gold to precipitate out. Placer deposit is formed by erosion and weathering, this is another common occurrence of gold (Lalomov et al, 2017).…”