No abstract

This study was carried out in order to understand the airborne geophysical signatures observed in the Jalapão region, Urucuia Basin, eastern Tocantins state. Airborne geophysical data (magnetic and gamma-ray spectrometry) and satellite images (Advanced Spaceborne Thermal Emission and Reflection Radiometer -ASTER) were processed and interpreted. I It was possible to characterize the main geomorphological units of the Jalapão region (residual landforms and dissected surfaces). The residual landforms (e.g., Serra do Espirito Santo and Occidental Baiano Plateau) have high concentrations of equivalent U (eU) and equivalent Th (eTh), and low K concentrations. ASTER image analysis suggests that these concentrations can be correlated with the products of chemical weathering (Fe oxides, clay, and weathering-resistant opaque minerals and other accessories). The dissected surfaces (mainly Jalapão Surface), however, is deficient in these radioelements, probably due to the quartz-rich nature of the related soils. Furthermore, the Jalapão Surface is practically non-magnetic, whereas residual landforms exhibit magnetic signals of low amplitude and high frequency, and are of unknown origin. The results suggest that the sources of these magnetic anomalies are shallow (≈ 270 m) and could be associated with ferrimagnetic minerals present in the alteration zone and/or in the ferruginous cements of the Serra das Araras Formation sandstones. The depth to basement in the region of this basin (1.44 km) rules out the possibility that the magnetic sources could be related to residual landforms.Understanding the origin of the airborne geophysical signatures of the Jalapão geomorphological units, Urucuia Basin, Central-Northern Brazil Accepted manuscript -Uncorrected pre-proofThis is a PDF file containing an unedited and non-definitive version of a manuscript that has been accepted for publication by the Journal of the Geological Survey of Brazil -JGSB, which serves to provide early visibility of the article. Being an uncorrected preproof version, errors may appear during the production process (language review, formatting and proof review), and these can affect the final content of the article and all legal disclaimers (https://jgsb.cprm.gov.br/index.php/journal/6).

Brasileira de Geofísica Este texto foi preparado para a apresentação no V Simpósio Brasileiro de Geofísica, Salvador, 27 a 29 de novembro de 2012. Seu conteúdo foi revisado pelo Comitê Técnico do V SimBGf, mas não necessariamente representa a opinião da SBGf ou de seus associados. É proibida a reprodução total ou parcial deste material para propósitos comerciais sem prévia autorização da SBGf.

ABSTRACT. Noises are common events in seismic reflection that have very striking features in the seismograms, hindering the data processing and interpretation. The attenuation of seismic noise is a challenge, in general frequency filters are employed, but they often do not show good results. The characteristic of noise...Keywords: seismic noise, Empirical Mode Decomposition, Singular Value Decomposition. RESUMO. Ruídos são eventos comuns na sísmica de reflexão que possuem características bem marcantes nos sismogramas, atrapalhando o processamento e interpretação dos dados. A atenuação de ruídos sísmicos é um desafio, em geral são utilizados filtros de...Palavras-chave: ruídos sísmicos, Decomposição em Modos Empíricos, Decomposição em Valores Singulares.