Serra da Cangalha
Impact crater in Brazil
From Wikipedia, the free encyclopedia
Serra da Cangalha is an impact crater in Tocantins, Brazil.[1] The crater is between 12 and 13 kilometres (7.5 and 8.1 mi) in diameter, making it the second-largest known crater in Brazil.[2] Its was formed around 220 million years ago, during the Triassic.[3] The name means Pack-Saddle Mountains in Portuguese.
| Serra da Cangalha | |
|---|---|
| |
  Location within Brazil | |
| Location | |
| Impact crater structure | |
| Confidence | Confirmed |
| Diameter | c. 12.5 km |
| Age | c. 220 million years |
| Exposed | Yes |
| Drilled | Yes |
Description
The outer perimeter is a circular inward scarp around 12.5 kilometres (7.8 mi) in diameter on the largely undisturbed Cretaceous and upper Silurian sediments of the Parnaíba basin,[4] breached on the west, north, and south sides by drainage valleys. Within the perimeter there is a series of concentric circular valleys and a central basin, all at roughly the same elevation, separated by ring walls. Shuttle Radar Topography Mission imagery shows a faint ring about 11 kilometres (6.8 mi) in diameter, a second ring of gentle hills around 5.5 kilometres (3.4 mi) in diameter, and an inner ring of steeper hills, about 3 kilometres (1.9 mi) in diameter and up to 420 metres (1,380 ft) high, open to the northwest, surrounding a central basin about 2.2 kilometres (1.4 mi) in diameter.[5][6][7]
The impact origin is attested by the presence of impact breccias, quartzite shatter cones, and shocked quartz. The meteorite is believed to have struck the surface at a low oblique angle, 25 to 30 degrees, on dry land. Radial faults are present inside the crater, and some extend up to 16 kilometers from the center.[7] Disturbed and steeply inclined sediments from the Carboniferous and Devonian periods occur within the crater. A magnetic survey of the structure indicates that deformation within the crater extends to a depth of about 2 kilometres (1.2 mi).[3][5][6][8][9]
History and studies
The identification of the structure as an impact crater was first published in 1973 by Robert Dietz and B.M. French.[10][11] Shatter cones were reported by Beatty in 1980.[12] Impact breccias, impact melting, and shocked quartz were reported by McHone in his 1986 thesis.[13] A magnetic survey of the structure was published by A.A. Adepelumi and others in 2005.[6]
