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Interpretation of aerogeophysycal and gravity data from Serra da Mesa region, Goiás and Tocantins

Grant number: 11/19053-1
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): December 01, 2011
Effective date (End): June 30, 2012
Field of knowledge:Physical Sciences and Mathematics - Geosciences - Geophysics
Principal Investigator:Yára Regina Marangoni
Grantee:Murilo Bellini Lacerda
Home Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Tocantins Province is located between the São Francisco craton to the east and the Amazon craton to the west. It is limited to the north and south by Parnaíba and Paraná sedimentary basins, respectively. The Research Company of Mineral Resources (CPRM) conducted an aerial survey in the area, and provided magnetic and gamma spectrometry data, the Serra da Mesa project. IAG has terrestrial gravity data in the study area. In the map of total intensity of magnetic field, two anomalies stand out at 48.8oW e 127oS. The shape of the anomalies, positive-negative-positive, almost aligned in N-S direction indicates that the magnetization is almost exclusively induced, and near the magnetic equator (year of the survey: 1973). These magnetic anomalies have no gravity response, but coverage area of gravity data is very poor, precluding correlation between data. In the geological map of the region there are no mapped bodies in the coordinates of the anomalies, suggesting that these bodies do not outcrop. These anomalies appear to fit over linear magnetic structures, long and narrow in NE-SW direction. It is intended to study and investigate these anomalies. For this, data will be analyzed using filters in the frequency domain, with the technique of FFT (Fast Fourier Transform), and techniques to emphasize the magnetic signal of the anomalies of interest and define the edges of the bodies. Other filters and processing can be implemented as needed. At the end we will made an inversion of the body from the magnetic data.