Magnetic fabrics and microstructures of late to post-tectonic Paleoproterozoic intrusive bodies of the Piedra Alta Terrane, Río de la Plata Craton, Uruguay

FRANCESCHINIS, PABLO R.; RAPALINI, AUGUSTO E.; SÁNCHEZ BETTUCCI, LEDA; MILANESE, FLORENCIA N.

Querétaro

Congreso; V Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo; 2017

Nine paleoproterozoic intrusive bodies of the Piedra Alta terrain, in the west of Uruguay, with ages between 2.2 and 2.0Ga were sampled in order to obtain information on kinematics of the intrusives emplacement, degree of deformation and regional stress regime during intrusion from anisotropy studies of magnetic susceptibility (AMS). Petrographic thin sections were studied in order to obtain information about the degree of deformation and its potential influence in the AMS results. Most plutons show K1 subvertical axes and subvertical foliations planes with K3 in subhorizontal position suggesting an extensional N-S regional field controlling the magma ascent. This is consistent with the E-W structural grain of the Piedra Alta terrane, the geographic distribution of the plutons in the metamorphic San José belt.