Serra da Cangalha

The Serra da Cangalha is an impact crater in northeastern Brazil in the state of Tocantins, near the border with the state of Maranhão (8 ° 4 ' 48 " S, 46 ° 51' 36 " W 8:08 - 46.86Koordinaten: 8 ° 4 ' 48 " S, 46 ° 51 ' 36 " W).

The crater has a diameter of 12 to 13 km, making it the second largest known crater in Brazil. Its age is estimated at about 220 one million years ( Triassic period). The name means in Portuguese Pack Saddle Mountains.

Description

The outer ring is a circular inward steep slope with a diameter of about 12 km along pristine chalk and upper Silurian sediments of the Parnaíba Basin, with gaps in the west, north and south by river valleys. Inside the outer ring there is a series of concentric circular valleys and a central tank, all with approximately the same height, separated by ring-shaped walls. SRTM images show a faint ring of about 11 km in diameter, a second ring of low hills with 5-6 km in diameter, and an inner ring with steeper hills of about 3 km in diameter and up to 420 m altitude, which is open to the northwest and a central basin with about 2.2 km in diameter surrounded.

The origin is attested by an impact by the presence of Impaktbrekzien, quartzite cone of rays and shocked quartz. It is believed that the meteorite hit the Earth's surface at a shallow angle of 25 to 30 degrees on dry land. Radial distortions are present within the crater, and some reach up to 16 km from the center. Disturbed and steeply inclined sediments from the Carboniferous and Devonian period are to be found within the crater. A magnetic analysis of the structure showed that the deformation extends inside the crater to a depth of about 2 km.

History and Studies

The identification of the structure as an impact crater was first in 1973 by RS Dietz and B.M. French noted. Cone of rays found by Beatty in 1980. Impaktbrekzien, Impaktschmelze and shocked quartz were mentioned by McHone in his thesis in 1986. A magnetic Examine the structure of AA Adepelumi and others published in 2005.