NUEVO ESTUDIO PALEOMAGNÉTICO Y DE MAGNETISMO DE ROCAS REALIZADO EN EL ENJAMBRE DE DIQUES BÁSICOS DE NICO PÉREZ-ZAPICÁN, URUGUAY

M. CERVANTES-SOLANO; AVTO GOGUITCHAICHVILI; L. SANCHEZ BETTUCCI; JUAN MORALES; CLAUDIA GOGORZA; AUGUSTO RAPALINI

DF

Congreso; V Reunión de LatinMag; 2017

LatinMag - UNAM

We report the results of a new paleomagnetic and rock magnetism study carried out in a basic dyke swarm exposed in the surroundings of Nico Pérez and Zapicán, in Lavalleja department, Uruguay. The dykes are mainly of basaltic composition, roughly oriented E-W to NW-SE. Previous studies suggest that the principal intrusion occurred during the Jurassic period. In order to constrain the temporal and geochronological context of these dike swarms, a total of 153 samples from 21 sites were collected. Rock-magnetic experiments indicate the presence of magnetite or titano-magnetite poor in titanium as the main carrier of magnetization. Consistent palaeomagnetic directions were successfully determined in 14 of the 21 sites yielding normal, intermediate and reverse polarities. The presence of inverse and intermediate polarities indicates that the intrusion of the dykes occurred during a long period pointing an age greater than the beginning of the Cretaceous Normal Superchron. The average directions, discarding apparently intermediate polarity sites, isDec = 183.7°, Inc = 50.5°, α 95 = 9.5°, N = 11 corresponding to a mean virtual geomagnetic pole of PLat = 86.1° S, P Long = 179° E, A95 = 10.2°. This direction agrees with other poles, of similar quality, proposed for the same region and age, however, due to the high dispersion, it overlaps with the paleomagnetic directions obtained for older formations.