Anomalous electrical structure in the northwestern Parana Basin, Brazil, observed with broadband magnetotellurics

作者：Bologna Mauricio S^*; Nunes Higo O; Padilha Antonio L; Vitorello Icaro; Padua Marcelo B

来源：Journal of South American Earth Sciences, 2013, 42: 74-82.

DOI：10.1016/j.jsames.2012.07.006

• Electrical properties
• Magnetotellurics
• Parana Basin
• Lithospheric structure

The deep structure of the northern part of the Parana Basin has been investigated through the analysis of a SW-NE magnetotelluric (MT) profile composed of 24 broadband stations with periods from 0.001 to similar to 1000 s that are regularly spaced similar to 10 km apart. The SW portion of the profile crosses a negative Bouguer anomaly with amplitudes of similar to 20 mGal. Our analyses show that there are two lithospheric domains with different gravity and electric conductivity properties. In the regularized two-dimensional MT inversion model the mid-to-lower crust in the SW part of the profile is almost two orders in magnitude more conductive compared to the NE portion. This difference in conductivity extends to the uppermost mantle depths, suggesting the existence of a major lithospheric discontinuity in the north-central Parana Basin, locally coincident with the position of the Apore River. We interpret this discontinuity as a juxtaposition of terranes with distinct natures and ages, possibly as result of tectonic accretion during the formation of Western Gondwana.

• 出版日期2013-3