Spatial distribution and structural control on gold mineralisation in the Barberton Greenstone Belt (South Africa, Eswatini)
Résumé
The Barberton Greenstone Belt (BGB) contains
over 350 gold occurrences and an estimated production of
342 tons, mainly from Fairview, New Consort, Sheba and
Agnes mines. Many studies target these active mines to
understand gold mineralisation. This study focuses on the
distribution and structural control of hydrothermal veins,
including in old mining areas and low-grade gold
occurrences. The gold-bearing event is studied using
spatial statistical analysis combined with structural field
geology and mineralogical analysis. The
hydrothermal/gold occurrences are distributed in several
clusters. Two main tectonic events are involved in the
formation of hydrothermal veins. A main deformation event
related to large-scale folding and thrusting controls
emplacement of gold-bearing veins during a single or
pulsed NW-SE shortening in the northern BGB, and during
an E-W shortening in the southern BGB. A late
deformation event, produced by NE-SW shortening in the
southern BGB is also related to late hydrothermal quartz
veins. Quartz-carbonate veins are found in the northern
mineralised system, whereas quartz-tourmaline-feldsparscarbonate
+/- sulfides veins are present mainly in the
southern BGB. The mineralised event in the BGB is
structurally controlled by the main NW-SE to E-W
shortening whereas additional quartz systems, not The Barberton Greenstone Belt (BGB) contains
over 350 gold occurrences and an estimated production of
342 tons, mainly from Fairview, New Consort, Sheba and
Agnes mines. Many studies target these active mines to
understand gold mineralisation. This study focuses on the
distribution and structural control of hydrothermal veins,
including in old mining areas and low-grade gold
occurrences. The gold-bearing event is studied using
spatial statistical analysis combined with structural field
geology and mineralogical analysis. The
hydrothermal/gold occurrences are distributed in several
clusters. Two main tectonic events are involved in the
formation of hydrothermal veins. A main deformation event
related to large-scale folding and thrusting controls
emplacement of gold-bearing veins during a single or
pulsed NW-SE shortening in the northern BGB, and during
an E-W shortening in the southern BGB. A late
deformation event, produced by NE-SW shortening in the
southern BGB is also related to late hydrothermal quartz
veins. Quartz-carbonate veins are found in the northern
mineralised system, whereas quartz-tourmaline-feldsparscarbonate
+/- sulfides veins are present mainly in the
southern BGB. The mineralised event in the BGB is
structurally controlled by the main NW-SE to E-W
shortening whereas additional quartz systems, notThe Barberton Greenstone Belt (BGB) contains
over 350 gold occurrences and an estimated production of
342 tons, mainly from Fairview, New Consort, Sheba and
Agnes mines. Many studies target these active mines to
understand gold mineralisation. This study focuses on the
distribution and structural control of hydrothermal veins,
including in old mining areas and low-grade gold
occurrences. The gold-bearing event is studied using
spatial statistical analysis combined with structural field
geology and mineralogical analysis. The
hydrothermal/gold occurrences are distributed in several
clusters. Two main tectonic events are involved in the
formation of hydrothermal veins. A main deformation event
related to large-scale folding and thrusting controls
emplacement of gold-bearing veins during a single or
pulsed NW-SE shortening in the northern BGB, and during
an E-W shortening in the southern BGB. A late
deformation event, produced by NE-SW shortening in the
southern BGB is also related to late hydrothermal quartz
veins. Quartz-carbonate veins are found in the northern
mineralised system, whereas quartz-tourmaline-feldsparscarbonate
+/- sulfides veins are present mainly in the
southern BGB. The mineralised event in the BGB is
structurally controlled by the main NW-SE to E-W
shortening whereas additional quartz systems, not
mineralised, seem to be controlled by an enigmatic NESW
shortening.