Geophysical characterization of the remanent anomaly in the Paleo/Mesoproteozoic Araí Intracontinental Rift, Brazil

Summary

We investigated a remanent anomaly in the main part of a Brazilian intracontinental Paleo/Mesoproterozoic rift using different geophysical methods. To enhance the anomaly signature at different depths we used RTP, DZ, THDR, 3D-AS, and UpCon techniques, generating a magnetic-structural interpretation of the main non-mapped features of the region. To identify the presence of non- induced magnetization in this particular anomaly and its total magnetization direction, we used the Maxi-Min, Magnetic Vector Inversion and Helbig’s Magnetic Moment Analysis techniques. We found total magnetization inclination and declination (I, D) of (49.10, -25.10), (46.30, -10.05) and (43.94, -19.53), respectively.

Based only on the TMI, we modelled this anomaly considering remanence using Magnetic Vector Inversion technique. Two bodies of great extension were identified at depths ranging between ~9 and 20 km. The anomaly was interpreted as a within-plate mafic pluton representing a magma chamber of continental tholeiitic association with associated feeder conduits. These results are crucial to understand the tectonic evolutional framework from this region affected by several superimposed events, including the Neoproterozoic Brasiliano Orogeny.

• remanent
• rift
• inversion
• Proterozoic
• magnetic