Investigation of the Goias Alkaline Province, Central Brazil: Application of gravity and magnetic methods

Autor(es)

Dutra, Alanna C. ^[1] ; Marangoni, Yara R. ^[1] ; Junqueira-Brod, Tereza C. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Geophys, Inst Astron Geophys & Atmospher Sci, BR-05508090 Sao Paulo - Brazil

^[2] Univ Fed Goias, Inst Estudos Socio Ambientais, BR-74000000 Goiania, Go - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of South American Earth Sciences; v. 33, n. 1, p. 43-55, FEB 2012.
• Citações Web of Science: 12

Resumo

We investigate the strong magnetic and gravity anomalies of the Goias Alkaline Province (GAP), a region of Late Cretaceous alkaline magmatism along the northern border of the Parana Basin, Brazil. The alkaline complexes (eight of which are present in outcrops, two others inferred from magnetic signals) are characterized by a series of small intrusions forming almost circular magnetic and gravimetric anomalies varying from -4000 to +6000 nT and from -10 to +40 mGal, respectively. We used the Aneuler method and Analytical Signal Amplitude to obtain depth and geometry for mapped sources from the magnetic anomaly data. These results were used as the reference models in the 3D gravity inversion. The 3D inversion results show that the alkaline intrusions have depths of 10-12 km. The intrusions in the northern GAP follow two alignments and have different sizes. In the anomaly magnetic map, dominant guidelines correlate strongly with the extensional regimes that correlate with the rise of alkaline magmatism. The emplacement of these intrusions marks mechanical discontinuities and zones of weakness in the upper crust. According to the 3D inversion results, those intrusions are located within the upper crust (from the surface to 18 km depth) and have spheres as the preferable geometry. Such spherical shapes are more consistent with magmatic chambers instead of plug intrusions. The Registro do Araguaia anomaly (similar to 15 by 25 km) has a particular magnetic signature that indicates that the top is deeper than 1500 m. North of this circular anomaly are lineaments with structural indices indicating contacts on their edges and dikes/sills in the interiors. Results of 3D inversion of magnetic and gravity data suggest that the Registro do Araguaia is the largest body in the area, reaching 18 km depth and indicating a circular layered structure. (C) 2011 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 07/53179-7 - Inversao tridimensional de dados gravimetricos e magneticos das alcalinas da provincia ipora - rio verde: investigando o controle tectonico.
• Beneficiário: Yára Regina Marangoni
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 06/00201-2 - Inversao tridimensional de dados gravimetricos e magneticos das alcalinas da provincia ipora-rio verde: investigando o controle tectonico.
• Beneficiário: Alanna Costa Dutra
• Modalidade de apoio: Bolsas no Brasil - Doutorado