Before the discovery of hydrothermal-gold-mineralization overprints on the placer gold deposit at Damang, near Tarkwa, it was widely thought that the Tarkwaian Group of rocks exclusively contained placer gold. The interception of hydrothermal gold mineralization within the Kawere sandstone and quartzite at the Kobeda and Badukrom prospects, is beginning to revolutionize the perception that hydrothermal gold mineralization in the Tarkwaian Group may be more extensive than previously believed. This chapter describes the mineralogical and geochemical attributes of the hydrothermal gold potential of the Badukrom prospect, emphasizing on its exploratory implications in the region. Dark grey sandstone/quartzite were heterogeneously albitized to pink-colored sandstone/quartzite prior to the hydrothermal gold mineralisation event. Following this pink alteration, hydrothermal ore-forming fluid was introduced, which caused the grey and pink sandstone/quartzite to be altered to light grey and light pink sandstone/quartzite, respectively. Most of the ore-associated minerals including gold were deposited in the light grey sandstone. This indicates that the alteration hues will be a useful exploratory tool in the field. In comparison to Damang, both deposits are located in the Tarkwaian Group and are related to quartz ± tourmaline ± carbonate veins with phyllic and propylitic alteration, tourmalinization and sulfidation of the wall rock. However, the Badukrom prospect is associated with a dominant pyrite-arsenopyrite ore assemblage and Au–Ag–Te–Sb–S–As–Se elemental signature while a pyrite-pyrrhotite assemblage and Au–Ag–Te–Sb–S–Bi–W association have been identified for the Damang deposit. Therefore, it is possible that similar hydrothermal gold-forming fluids may exist in the Tarkwa-Damang area. Thus, in addition to the alteration hues, exploration strategies to identify, map and exploit regional and local structures may yield potential ore-bearing quartz veins related to these fluid systems in the region.

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Footprint of Hydrothermal Gold Mineralization in the Kawere Sandstone, Tarkwaian Group, Ghana: Findings from Two Drillhole Intersections at the Badukrom Prospect, Iduapriem

  • Kofi Adomako-Ansah,
  • Charles Kusi-Manu,
  • Michael Affam,
  • Emmanuel Amekudzi,
  • Yamoa Munko-Abo,
  • Divine Kwapong,
  • Kofi Poku Osei,
  • Justice Lawerh

摘要

Before the discovery of hydrothermal-gold-mineralization overprints on the placer gold deposit at Damang, near Tarkwa, it was widely thought that the Tarkwaian Group of rocks exclusively contained placer gold. The interception of hydrothermal gold mineralization within the Kawere sandstone and quartzite at the Kobeda and Badukrom prospects, is beginning to revolutionize the perception that hydrothermal gold mineralization in the Tarkwaian Group may be more extensive than previously believed. This chapter describes the mineralogical and geochemical attributes of the hydrothermal gold potential of the Badukrom prospect, emphasizing on its exploratory implications in the region. Dark grey sandstone/quartzite were heterogeneously albitized to pink-colored sandstone/quartzite prior to the hydrothermal gold mineralisation event. Following this pink alteration, hydrothermal ore-forming fluid was introduced, which caused the grey and pink sandstone/quartzite to be altered to light grey and light pink sandstone/quartzite, respectively. Most of the ore-associated minerals including gold were deposited in the light grey sandstone. This indicates that the alteration hues will be a useful exploratory tool in the field. In comparison to Damang, both deposits are located in the Tarkwaian Group and are related to quartz ± tourmaline ± carbonate veins with phyllic and propylitic alteration, tourmalinization and sulfidation of the wall rock. However, the Badukrom prospect is associated with a dominant pyrite-arsenopyrite ore assemblage and Au–Ag–Te–Sb–S–As–Se elemental signature while a pyrite-pyrrhotite assemblage and Au–Ag–Te–Sb–S–Bi–W association have been identified for the Damang deposit. Therefore, it is possible that similar hydrothermal gold-forming fluids may exist in the Tarkwa-Damang area. Thus, in addition to the alteration hues, exploration strategies to identify, map and exploit regional and local structures may yield potential ore-bearing quartz veins related to these fluid systems in the region.