Abstract
This study concerns itself with a comparison of tectonic structural control components
for speleogenic propagation in the Cradle of Humankind UNESCO world heritage site 40 km
NW of Johannesburg, and in the Far West Rand. From the Cradle of Humankind area, the
Rising Star system situated at S26o 00.951′ E27o 44.071′ and Bats cave at S26o 02.008′; E27o
44.089′ were selected as they show the typical collective morphology and structural overprint
of the majority of caves found in the area-showing cave genesis within this region to have
been predominantly influenced by lithological, layer parallel controls interacting with crosscutting
fracture systems reflecting an NW to SE directed extensional far-field stress.
Armageddon Pot situated at 26o 23.517′ E27o 43.562′ in the vicinity of Westonaria, taken as
an example of speleogenesis in the Far West Rand, is a massively developed linear cavity
measuring ±2600 m in explored length and ±257m in depth. Its cave entrance is located at the
bottom of a 50 m deep sinkhole that formed in the 1990’s due to stoping, gradually
weakening the roof until it was structurally compromised.
Armageddon Pot is situated along the southern margins of the Panvlakte/Witpoortjie horst
domain. Its chief initiating structural control is a normal fault striking east to west and
dipping at ±75o north to south. This structure appears clearly linked with the broader
structural characteristics of the Panvlakte/Witpoortjie horst block domain (a succession of
elevated crustal blocks of Witwatersrand Supergroup units), that in turn has a direct causal
relationship with deep-seated Witwatersrand tectonics.
This normal fault, as Armageddon’s chief linear structural control, is transverse (crossed) by
older Pre-genetic (sub-horizontal) offset shear zones and numerous interleaved micro-shears.
Along these offset shear zones, massive cataclasite bodies occur that enclose compressional
as well as extensional structures. This has not been observed before in caves within the CoH...
M.Sc. (Geology)