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Electromagnetic imaging of a transpressional tectonics in SW Iberia
Author(s) -
Almeida Eugénio,
Pous Jaume,
Santos F. Monteiro,
Fonseca Paulo,
Marcuello Alex,
Queralt Pilar,
Nolasco Rita,
MendesVictor Luís
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012037
Subject(s) - geology , shear zone , magnetotellurics , crust , tectonics , pluton , transition zone , geochemistry , seismology , geophysics , electrical resistivity and conductivity , engineering , electrical engineering
Forty‐one magnetotelluric soundings were carried out along a 200 km‐long profile (approximately NNE‐SSW) across the three major geotectonic units in SW Iberia. A model obtained from two‐dimensional inversion of the magnetotelluric data set reveals high conductivity zones in the middle‐lower crust (10–30 km). Two of these zones correspond to the transition between the main geotectonic units: one between the South Portuguese Zone and the Ossa Morena Zone, interpreted as having been caused by metasediments, and the other between the Ossa Morena Zone and the Central Iberia Zone associated with a shear zone and metasediments. Another high conductivity anomaly related to black shales with major graphite impregnation was detected within the Ossa Morena Zone. The resistive features, located preferentially in the upper crust (1–10 km), coincide with gabbroic and granitic complexes.