Tectonic Insight in the Southwest Gondwana Boundary Based on Anisotropy of Magnetic Susceptibility

ARZADÚN GUADALUPE; TOMEZZOLI RENATA NELA; TICKYJ HUGO; CRISTALLINI ERNESTO OSVALDO

Tectonics Evgenii Sharkov

Intechopen

Lugar: Londres; Año: 2017; p. 13 - 32

The anisotropy of magnetic susceptibility (AMS) is an effective tool to measure the rockpetrofabric and it allow analyzing the tectonic stress. The southwest boundary of Gondwanain South America is the counter-part of the Cape fold belt of South Africa and itsgeological evolution is still a subject of debate. Samples of different localities of this sectorwere analyzed with the AMS technique, from Buenos Aires, La Pampa and Mendozaprovince. For rocks of Permian age, there is a clear regional magnetic signature indicatinga NW-SE elongation direction and a NE-SW shortening. The ASM patterns obtained in theoldest rocks are complex, probably as the result of stress interference in the magnitudes,space and time with different pulses of the orogenic activity developed from the MiddleDevonian to the Permian. In the southwest of Gondwana, small continental plates wereaccreted to the main continent mass during the Middle Devonian. The Permian deformationhas been interpreted as the consequence of a paleogeographic re-organization ofGondwana that moves to lowest latitudes to makes the Pangea continent during theTriassic. This younger deformation evidences an orogenic front migration and attenuationto the foreland basin.