A 3-D MT model for the central portion of Paraná Basin with emphasis on the Ponta Grossa Arch

Abstract

A geoelectric model is proposed for the central part of Paraná Basin. A major part of the intracratonic basin has one of the most voluminous flood basalt inshore complex up to 2 km thick, covering an area of some 800,000 km2. The basalt overlies a series of Paleozoic sediments including hydrocarbon source rocks. This paper presents a three-dimensional (3-D) geoelectric model for the central portion of the basin, based on a dataset comprising 136 broadband magnetotelluric (MT) sites with a frequency range spanning from 0.003 Hz to 250 Hz, covering an area of 120,000 km2. The MT sites were deployed along 8 profiles running SW-NE profiles and one NW-SE profile. The obtained model reveals the sedimentary basin structure through its basement, reaching lower crustal depths. In particular it has revealed a more complex structure for the Ponta Grossa Arch than the models previously thought. There is some indication of accretion of mantle materials in the base of the crust. This is suggested by oscillations in thickness of the crust and zoning of enhanced conductivity values. The results emphasize the feasibility of 3-D forward modeling in practice.