Mt-Lmt Imaging of Transbrasiliano Lineament and Basement-Cover Relationship in Parnaíba Basin

A major multi-disciplinary and multi-institutional project has been established to probe the deep structure across the Borborema Province of northeast Brazil. Broadband and long period MT data were recorded at 46 stations, with 10 km spacing along a profile crossing the Parnaíba basin and outcropping basement complex of Borborema province. The MT data were processed using a robust scheme and transfer functions were obtained in the period range of 0.001 – 10,000 sec. Regularized 2D inversion of the data reveals the deep resistivity structure of the Parnaíba basin down to 80 km depth. The sedimentary top crustal section is conductive (<15 ohm.m) while the deep crust and upper mantle are resistive (>100 ohm.m). We found that the major surface lineaments could penetrate into the deep crust, and that there are also two anomalous 10-20 km-wide conductive zones at ~50 km depth which may be related to magmatism on the surface.