Open AccessA magnetotelluric investigation of the Araguainha impact structure in Mato Grosso‐Goiás, central Brazil
Author(s) -
Masero W.,
Schnegg P.A.,
Fontes S. L.
Publication year - 1994
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1994.tb01803.x
Subject(s) - magnetotellurics , geology , outcrop , basement , impact structure , seismology , dome (geology) , anisotropy , electrical resistivity and conductivity , paleontology , geography , archaeology , impact crater , physics , quantum mechanics , astronomy
SUMMARY With a diameter of 40 km the Araguainha Dome is the largest known impact site in South America. The main characteristics of the structure is its appearance as a set of imbricated circles and a central uplift with a diameter of 9 km. 25 magnetotelluric (MT) soundings were completed across the structure, approximately defining five radial sections. The MT responses in the frequency range from 1000 to 1 HZ show 1‐D behaviour, in contrast to the longer periods where data indicate a strong anisotropy and a decline of the resistivity. 1‐D modelling of the high‐frequency data reveals a well‐defined symmetric crystalline basement ring at 1000 m depth between the radii of 9 and 20 km, which seems to drop deeper further away from the centre. Inside the ring and toward the centre, the top of the granites rises, outcropping at 1.5 to 2 km from the centre.