THE GEOMETRY AND STRUCTURAL ANALYSIS OF THE GOLD DEPOSITS OF CHIRANO MINE

  • Kwamina Ackun-Wood Chirano Gold Mines Ltd
  • Jerry S.Y Kuma University of Mines and Technology, UMaT, Tarkwa
  • Jerome Anabannye Yendaw University of Mines and Technology, Tarkwa
Keywords: ductile, brittle-ductile, brecciated, Chirano Shear Zone, Chirano Lode Horizon.

Abstract

The Chirano Mine gold deposit is a typical example of a structurally controlled deposit developed along the Kumasi Basin and the Sefwi Belt margin structure. The area has undergone various regimes of structural deformations. Consequently, all the Chirano deposits are intimately associated with shears and faults along a single continuous structural corridor known as the Chirano Shear Zone (CSZ). The CSZ geometry has been categorised into three major zones namely: (i) Laminated veins in shears, (ii) Breccia and (iii) Ductile to brittle ductile zones. The shear veins trend NE-SW and N-S, are laminated and occur in the sheared fabric close to the footwall. Penetrative foliated zones varying from a few centimeters to several meters constitute the ductile to brittle ductile structures. Gold grades are much higher within this zone. Analysis of cataclasis intensity recorded in drill core confirms a semi brittle form of deformation within the mineralised domain. The CSZ has different orientations in dip and strike from the south of the mining lease to the north. The subtle changes in orientation are deposit dependent. The structure has a sinuous shape and tends to pinch and swell. The current geometry and the distribution of stratigraphy and orebodies at Chirano is a manifestation of the complex interplay of magmatic and hydrothermal events in the area.

Author Biographies

Kwamina Ackun-Wood, Chirano Gold Mines Ltd
Exploration  Dept
Jerry S.Y Kuma, University of Mines and Technology, UMaT, Tarkwa
Vuce Chancellor
Jerome Anabannye Yendaw, University of Mines and Technology, Tarkwa
Geological Engineering Dept

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Published
2016-12-20
Section
Geological Eng. Article