Examkin

Question

Difficulty: Very hardMineral Resources and Mining in Africa

The Witwatersrand basin in South Africa is recognized globally as one of the most prolific gold-producing regions in history. Which of the following statements correctly identifies the geological host environment of these gold deposits and a major physical constraint encountered during their extraction?

  1. A
    The gold deposits are hosted within young metamorphic marble formations, making open-cast strip mining along riverbanks the standard extraction technique.
  2. The gold occurs within ancient Precambrian sedimentary conglomerates, with ultra-deep shaft mining constrained by extreme geothermal heat and severe rock pressure.Answer
  3. C
    The gold reserves represent a continuously replenishing renewable mineral resource generated by ongoing volcanic eruptions along the East African Rift System.
  4. D
    The gold ore is a weight-losing raw material that requires processing plants to be located exclusively at maritime shipping ports under Weber's location principles.

Answer

The Witwatersrand gold deposits occur within ancient Precambrian conglomerate rock layers, and mining operations face severe physical constraints due to extreme rock temperatures and high lithostatic pressure at depths exceeding 3,000 meters.
The Witwatersrand gold reserves are embedded within Precambrian banket (conglomerate) rock strata. Because surface deposits were exhausted early, extraction requires ultra-deep vertical shaft systems. At depths exceeding 3,000 meters, miners encounter severe physical challenges, including ambient rock temperatures rising above 50°C (requiring massive refrigeration) and high lithostatic pressure causing catastrophic rockbursts.

Step-by-Step Solution

1
Analyze the geological setting of the Witwatersrand goldfields in South Africa.
The Witwatersrand basin consists of Archean/Precambrian sedimentary sequence beds containing auriferous (gold-bearing) pebble conglomerates known locally as 'reefs'.
Understanding the host rock classification distinguishes Precambrian sedimentary conglomerates from younger metamorphic or igneous rocks.
2
Evaluate the operational mining techniques and physical hazards of the basin.
Due to the steep inclination and immense depth of the seams (reaching over 3.5 to 4 km underground), deep vertical shaft mining is mandatory, introducing extreme geothermal gradients (high temperatures) and rockburst risks.
Surface open-cast mining is unsuitable for ultra-deep reef gold seams.
3
Synthesize the correct option combination.
The correct combination describes Precambrian sedimentary conglomerates paired with deep shaft mining challenges arising from extreme geothermal heat and rock pressure.
This accurately reflects both the physical geology and economic geography of South African mining.

Key Concept

Geological occurrence and deep-shaft mining constraints of South Africa's Witwatersrand goldfield
Rate this question

Topics

Mineral Resources and Mining in Africa

More questions from this topic