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Gold deposits associated with the gabbroic rocks at Tirek area, western Hoggar, Algeria: fluid inclusion study

  • Warda Saad
  • Djamal Eddine Aissa
  • Koichiro Watanabe
  • Sachihiro Taguchi
Original Paper
  • 157 Downloads

Abstract

The Tirek gold deposit hosted in the Archean shield is one of the richest sources of mined gold for Algeria. The deposit is controlled by the East Ouzzal shear zone (EOSZ), a transcurrent N–S lithospheric fault. The EOSZ is a late Pan-African dextral-ductile shear zone separating two contrasting Precambrian domains: the Archean In Ouzzal block to the west (Orthogenesis with subordinate metasediments reworked and granulitized during the ca. 2 Ga Eburnean event) and a middle Proterozoic block to the east involved in the ca. 600 Ma Pan-African event. The auriferous quartz veins are mainly oriented in two directions, N–S veins hosted in mylonitic rocks and NE–SW veins hosted in gabbroic or gneissic bands. The NE–SW veins contain the richest ore. Gold ore is found in a system of veins and lenticular quartz veinlets arranged in anastomosing networks. The hydrothermal alteration associated with these veins is characteristically a carbonate-sericite-albite-pyrite assemblage. Gold is the main metal of economic importance; it is disseminated in the quartz as grains or fibers along microcracks and as microscopic grains in the host rocks. Microthermometric results and Raman laser data from fluid inclusions demonstrate that the ore-forming fluids contained H2O-CO2±CH4 and were low salinity. Homogenization temperatures are commonly 250–310 °C. In the Tirek deposit, the role of the shear zone that hosts the mineralization was to drain the hydrothermal fluid. Interactions between the fluid and the mafic host rocks and CO2 also contributed to the formation of the hydrothermal gold deposit at Tirek.

Keywords

Tirek gold deposit Shear zone Hoggar Fluid inclusions 

Notes

Acknowledgements

The manager and staff of Tirek-Amesmessa Gold Mine are deeply appreciated for their assistance during the field work.

Honest thanks are extended to the staff of the Department of Engineering and Mineral Resources, Kyushu University, Japan. Especially the Associate professor Mr. Kotaro Yonezu, Mr. Hakim Saibi, Dr. Thomas Tindell, and Dr. Jillian Aira Gabo.

Funding information

The laboratory analysis was financially supported by JASSO scholarship.

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Copyright information

© Saudi Society for Geosciences 2018

Authors and Affiliations

  1. 1.Laboratory of Metallogeny and Magmatism of Algeria, Department of Geology, Faculty of Earth Science and Country PlanningUniversity of Sciences and Technology Houari BoumedieneAlgiersAlgeria
  2. 2.Department of Earth Resources Engineering, Faculty of EngineeringKyushu UniversityFukuokaJapan
  3. 3.Department of Earth System Science, Faculty of ScienceFukuoka UniversityFukuokaJapan

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