Serra da Cangalha
Template:Short description Template:Infobox terrestrial impact site Serra da Cangalha is an impact crater in the State of Tocantins, near the border of Maranhão State, in north/northeastern Brazil.[1] The crater is between Script error: No such module "convert". in diameter, making it the second-largest known crater in Brazil.[2] Its age is estimated to be about 220 million years (Triassic period).[3] The name means Pack-Saddle Mountains in Portuguese.
Description
The outer perimeter is a circular inward scarp about Script error: No such module "convert". 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 Script error: No such module "convert". in diameter, a second ring of gentle hills about Script error: No such module "convert". in diameter, and an inner ring of steeper hills, about Script error: No such module "convert". in diameter and up to Script error: No such module "convert". high, open to the northwest, surrounding a central basin about Script error: No such module "convert". 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 km 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 Script error: No such module "convert"..[3][5][6][8][9]
History and studies
The identification of the structure as an impact crater was first published in 1973 by R.S. 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]
See also
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References
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