Metasediments in the Alahina Sector and Associated Mineralization (North-Eastern Guinea)

• 作者: Christophe Kaki Glodji Luc Adissin Koffi Germain Tchokpon Mory Kourouma Soulémana Yessoufou
• 来源期刊: 地质学期刊(英文)
• 学科: 地球科学
• 关键词: Metasediment SCHIST SERICITE CHLORITE VEIN Quartz Gold Alahina Siguiri Basin
• 年，卷（期）: 2019,（12）
• 页码范围: 897-918
• 页数: 22页
• 分类号: P58

摘要

The Alahina sector is located in the North-East of Guinea, precisely in the Siguiri volcano-sedimentary basin. It consists mainly of meta-sediments traversed by Paleoproterozoic pyroclastite, granite, monzogranite and granodiorite veins as well as Mesozoic dolerite and gabbros veins. This article presents new data, on the one hand, on the geochemical petrographic features and the origin of the metasediments of this zone, and on the other hand, on the genetic model of the gold mineralization that they contain. Field observations, as well as petrographic and geochemical studies reveal that the meta-sediments consist of sericite and chlorite schists. They belong to the groups of shales and grauwackes. Their protholites are moderately altered (60 N/YbN = 6.31 - 13.24) and a flat heavy rare earth patterns (HREE). This spectrum is almost identical to those of the “Post-Archean average Australian Shale” and Early Proterozoic Greywackes. Two types of polyphase gold mineralization occur in the Alahina sector: disseminated and veined. They consist of particular of grains and nanoparticles pyrite associated with gold, magnetite, hematite, ilmenite. The hydrothermal alteration accompanying this mineralization consists of silica, microcline, chlorite-epidote-sericite-carbonates.