Vredefort crater
- 2727.5Koordinaten: 27 ° 0 ' 0 " S, 27 ° 30' 0" E
The Vredefort crater ( also Vredefort structure, Vredefort Dome Vredefort Impact and Site ) in South Africa's Free State Province is the largest safely identified impact craters on earth.
Geographical location
The Vredefort crater is located in the north of the Free State Province about 120 kilometers (km ) southwest of Johannesburg, about the same distance south of the Witwatersrand mountain range and 75 km (each air line) west of the Vaal Dam. It spreads in the Witwatersrand Basin at Vredefort from.
Description, history, geology
Different reportedly trained there the impact of an asteroid that probably had 10 km in diameter, a good two billion years ago ( exact date based of found Zirkonkristallen: 2023 / - 5 mya ) a up to 320 km long and 180 km wide crater with multiple rings. By the impact of a hole depth of 40 km and 100 km in diameter was torn in the earth's crust originally, the walls collapsed soon after the impact and the crater above, around 10 km deep left. Because of erosion and plate tectonics is of these rings, but now only the Vredefort ring present at about 50 km in diameter in the northwestern part of the crater.
In the center of the Vredefort crater is the Vredefort Dome, a dome-like bulge, which was supposed at first that she was of volcanic origin. This was disproved until the mid- 1990s. Numerous finds of impactites and radiation cones but testify of the origin of the Vredefort structure by a meteorite impact.
In 2005, various geological formations have been declared in the area of the crater by the UNESCO World Heritage Site. These are:
- The region of the dome
- A fault with stromatolites
- A breccia - reference (chocolate tablet )
- Pseudotachylit a quarry