2-D Inversion of magnetic data and gravity modelling of the transition zone between the Pernambuco-Alagoas domain and the northern portion of the Sergipano Belt (NE, Brazil)

Priscilla Alvarez,Allana Costa Dutra

doi:10.21680/2447-3359.2021v7n2id22049

Priscilla Alvarez, Allana Costa Dutra

Open Access

https://doi.org/10.21680/2447-3359.2021v7n2id22049

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Abstract

Two-dimensional magnetic inversions were performed with the purpose to obtain information about the magnetic susceptibility, depth and volume of true magnetic sources located in the basement adjacent to the Sergipe-Alagoas basin, in the transition zone between the Pernambuco-Alagoas Domain and the northern portion of the Sergipano Belt (Borborema Province, NE Brazil) and to delineate its geometries. The magnetic data processing was performed to interpret geological contacts, source’s edge boundaries and mapping of folds and shear zones. In the results of the magnetic inversion, a source was found in the Rio Coruripe domain between 9 and 21 km in depth with a magnetic susceptibility of 0.0079 (SI) and another in the Pernambuco-Alagoas domain between 7.5 and 9 km with a magnetic susceptibility of 0.0077 (SI). The basement’s depth was obtained through spectral analysis, whose base was found at 37.7 km. In addition, gravity models were created with the purpose to verify the information obtained by the magnetic inversion and spectral analysis, which was useful to understand how these sources interfere in the structure of the basement and how it affected its tectonic model.

Highlights

The Sergipe-Alagoas basin is located at the continental margin of the Brazilian northeast region, with an area of approximately 45.000 km2 and has a good potential for oil exploration and production in ultra-deep waters, which represents high interest for the oil industry and makes important the development of researches in this area
We focus on the transition zone between the Pernambuco-Alagoas (PEAL) domain and the northern portion of the Sergipano Belt, located in the southern portion of the Borborema Province (Neves et al, 2016)
The analysis was applied on polygons with 25 km2, 50 km2, 100 km2, 150 km2 and 200 km2 taken from the Total Magnetic Field Anomaly Map (Figure 5.a) and performed on a program in Matlab code

Summary

Introduction

The Sergipe-Alagoas basin is located at the continental margin of the Brazilian northeast region, with an area of approximately 45.000 km and has a good potential for oil exploration and production in ultra-deep waters, which represents high interest for the oil industry and makes important the development of researches in this area. The description of the geological context of the Sergipe-Alagoas basin has been well explained by dos Santos et al (1998), subsurface models are scarce, and makes this one of the main objects of study of this research. The Macururé Complex and the low-grade to unmetamorphosed domains of the southern Sergipano Belt correspond to distal and proximal facies, respectively, of platform sediments deposited onto the passive continental margin of the São Francisco Craton. In this model, the suture zone separating the two plates would be located close to the transition zone (dos Santos et al, 1998)

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