Pilanesberg
Ancient volcanic structure in South Africa
From Wikipedia, the free encyclopedia
The Pilanesberg (formerly Pilandsberg[2][3]) is a mountain in the North West Province, South Africa. The mountain is an ancient volcanic structure, circular in shape, that rises from flat surrounding plains. It is formed by three concentric ridges or rings of hills, of which the outermost has a diameter of about 24 km. The Pilanesberg is located 100 km to the North-West of Pretoria and is for the greater part enclosed in a protected area known as Pilanesberg National Park.
| Pilanesberg | |
|---|---|
NASA picture of Pilanesberg with Vaalkop Dam on the right side | |
| Highest point | |
| Elevation | 1,687 m (5,535 ft)[1] |
| Listing | List of mountains in South Africa |
| Coordinates | 25°14′25″S 27°4′33″E |
| Geography | |
  Pilanesberg Location within South Africa | |
| Location | North West Province |
| Parent range | Witwatersrand |
| Geology | |
| Rock age | Proterozoic |
| Extinct volcano | |
The Elands River flows South of the Pilanesberg in an Easterly direction. There are a number of platinum mines right at the perimeter of the crater formation.
The name "Pilanes" comes from a historic Tswana chief named Pilane.[4]
Geology
The Pilanesberg is the surface expression of the Pilanesberg Complex, a circular alkaline igneous complex covering about 625 square kilometres (241 sq mi). The complex was emplaced into rocks of the Bushveld Igneous Complex and contains coeval volcanic rocks and several distinct intrusive syenitic and foyaitic units that are arranged concentrically at the surface.[5]
Uranium–lead dating of titanite gives an emplacement age of 1,395 +10
−11 million years, during the Mesoproterozoic. The complex includes trachytes, phonolites, syenites and nepheline syenites. Preservation of part of its volcanic carapace distinguishes it from many other large alkaline complexes.[6]
The circular intrusive units were historically interpreted as a laccolith, a funnel-shaped body, or a system of ring dikes and cone sheets. Cawthorn argued that the principal coarse-grained bodies, which exceed 1 kilometre (0.62 mi) in radial width, are too wide and coarse-grained to be conventional ring dikes or cone sheets. Poor exposure makes the three-dimensional relationships among the intrusive units difficult to determine directly.[5]
