General Geology

Geology

The TGME Projects are situated within the Eastern Transvaal (Sabie-Pilgrims Rest) Gold Fields, approximately 300 km northeast of the Witwatersrand Basin (Figure 1). Regionally this section (north east South Africa) has produced over 2 Billion oz of gold, approximately 40-50% of World’s gold production. The region hosts the Bushveld Complex (Largest layered igneous intrusion on Earth) which contains approximately 80% of World’s PGM-bearing ore (Source: Mineral Council SA). The region also produces lots of coal, chrome, and base metals.

The Company dominates the Eastern Transvaal Gold Fields with a 620 km of tenement package covering 43 historical mines across nine (9) Mining Rights. A Mineral System Model (ore genesis and structural geology model) was developed to support the company’s exploration efforts. The new model interprets the role of the intrusive Bushveld Complex as the main source of gold-bearing fluids for the Eastern Transvaal Gold Fields (Figure 2 & 3). The gold bearing fluids interpreted as migrating along east-west structures (faults and joints) from the Bushveld Complex to the Eastern Transvaal Gold Fields.

Figure 1: Regional geology and Theta Gold Mines Mining Rights

Figure 2: Interpreted structural map and gold mineralisation diagram

Figure 3 Mineral Systems Model

Epigenetic gold mineralisation in the Eastern Transvaal Gold Fields (Sabie-Pilgrims Rest Goldfield) occurs as concordant (Chemical traps) and discordant (sub-vertical) (Structural straps) veins (or reefs) in a variety of host rocks within the East Transvaal Goldfield.  

Structural Traps

A rock chip sample with assay result of 83.97 g/t Au collected at Vaalhoek is over 60 km from Rietfontein samples (41.87 g/t Au, 22.85 g/t Au). Both Vaalhoek and Rietfontein have over 3 km of underground workings; both have a vertical component to the gold mineralization, which has been interpreted as a result of the NNE trending dykes forming structural traps (Figure 3) and causing gold deposition via the disruption of migrating mineralizing fluids. The setting for mineralization in both mines conform with the Mineral Systems Model.

Chemical Traps

The Frankfort/ Beverly Hills area is one of 43 historical mine workings. The shallow reef system has open-pit potential and fits the Chemical Trap style mineralization as indicated by the Mineral Systems Model (Figure 3). The East Transvaal Goldfield has 21 historical gold producing reefs that occur at different stratigraphic horizons within the siliciclastic and dolomitic host sediments. The major producing gold reefs are usually developed at the interface of carbonaceous shales and shallow water dolomitic sediments, which act as reducing environments (Chemical Traps) (Figure 4; stope reef section in dolomitic sediments).

Figure 4: Sampling at the old Frankfort Mine, Bevetts Reef, Beverly Hills area. Grades up to 3.2 g/t Au recorded. This is an oxide open-pit target.

Figure 5: Stratigraphic Succession of the Sabie-Pilgrims Rest Goldfields (Minxcon 2019)

Figure 6:Stratigraphy of Sabie Pilgrims Rest Goldfield

Principal gold mineralisation occurs

  • associated with vertical to subvertical structures hosted by 2.8 Ga Archean Granite and 2.2 Ga lower Proterozoic siliciclastics and dolomites (eg Rietfontein, Figure 6); 

  • within bedding parallel shear zones located within sedimentary host rocks of the 2.2 Ga Transvaal Supergroup (eg Beta, Figure 6); 

  • In association with regional thrusting on the Bevetts Unconformity which separates the Pretoria and Chuniespoort Groups 

  • Gold age ~ 1.98 Ga syn to late Bushveld Igneous Complex 


The regional structural geology is dominated by close space north east fault system (Figure 7). These faults have been the main fluid conduits for the gold mineralization. Often controlling the orientation of gold mineralising and deposition. This faults system remains under explored and is key to new discoveries.      

Figure 7 :Regional Geology Map with tenements and Historical Mine areas.