Um levantamento magnético terrestre foi realizado numa área do centro-leste da Ilha de Santa Catarina, para verificar a continuidade dos diques em subsuperfície na área das dunas da praia da Joaquina. Medidas de gradiente vertical em 1880 estações não revelaram nenhum sinal relacionado com anomalias magneticas produzidas por diques em subsuperfície. Quatro perfis localizados ao norte e sul da área principal de estudo detectaram a assinatura magnética de vários diques, alguns aflorantes (perfis-norte) mas também alguns em subsuperfície (perfis-sul). Estes resultados sugerem que os diques eram rasos e truncados e foram erodidos juntamente com o embasamento cristalino.

PALAVRAS-CHAVE:
Enxame de diques; Ilha de Santa Catarina; Mapeamento geofísico; Levantamentos terrestres; Métodos magnéticos

Autoria

George Caminha-Maciel ^**Corresponding author.

Universidade Federal de Santa Catarina - UFSC, Florianópolis (SC), Brasil. E-mail: caminha.maciel@ufsc.brUniversidade Federal de Santa CatarinaBrazilFlorianópolis, SC, BrazilUniversidade Federal de Santa Catarina - UFSC, Florianópolis (SC), Brasil. E-mail: caminha.maciel@ufsc.br

Marcia Ernesto

Universidade de São Paulo - USP, Departamento de Geofísica, São Paulo (SP), Brasil. E-mail: mernesto@usp.brUniversidade de São PauloBrazilSão Paulo, SP, BrazilUniversidade de São Paulo - USP, Departamento de Geofísica, São Paulo (SP), Brasil. E-mail: mernesto@usp.br

Welitom R. Borges

Universidade de Brasília - UnB, Brasília (DF), Brasil. E-mail: welitom@unb.brUniversidade de BrasíliaBrazilBrasília, DF, BrazilUniversidade de Brasília - UnB, Brasília (DF), Brasil. E-mail: welitom@unb.br

Junior Bresolin

Reginaldo Lemos

*Corresponding author.

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Figuras | Tabelas

Figuras (7)
Tabelas (1)

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Figure 1:
Sketch map of the Paraná Magmatic Province (left) indicating the main dyke swarms. The Santa Catarina island (center) indicating the study area. Geological map (Tomazzoli & Pellerin 2015Tomazzoli E.R., Pellerin J.M. 2015. Unidades do mapa geológico da ilha de Santa Catarina: as rochas. Geosul, 30(60):225-247.) of the study area (right) indicating the magnetic profiles and magnetic stations over the Joaquina beach.

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Figure 2:
Vertical gradient (VG) over the Joaquina dune field, drawn in Mirone software (Luis 2007Luis J.F. 2007. Mirone: A multi-purpose tool for exploring grid data. Computers & Geosciences, 33(1):31-41.). Black dots are the magnetic stations.

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Figure 3:
Upper continuation (at 100 m) of VG over Joaquina dune field, drawn in Mirone software (Luis 2007Luis J.F. 2007. Mirone: A multi-purpose tool for exploring grid data. Computers & Geosciences, 33(1):31-41.). Black dots are the magnetic stations.

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Figure 4:
Magnetic curves for the Mole profile (A-B). From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). Arrows on the AS curve indicate anomalies clearly related to dykes; BR means below resolution for reliable interpretation.

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Figure 5:
Magnetic curves for the Gravatá profile (C-D). From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). Arrows on the AS curve indicate anomalies clearly related to dykes; BR means below resolution for reliable interpretation. Shaded area in the TMI curve indicates the profile change in direction.

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Figure 6:
Magnetic curves for the south profile E-F. From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). Arrows on the AS curve indicate anomalies clearly related to dykes; BR means below resolution for reliable interpretation.

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Figure 7:
Magnetic curves for the south profile (G-H). From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). The arrow on the AS curve indicate anomaly clearly related to dyke.

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Table 1:
Magnetic derivatives applied to the 2D profiles.

Figure 1: Sketch map of the Paraná Magmatic Province (left) indicating the main dyke swarms. The Santa Catarina island (center) indicating the study area. Geological map (Tomazzoli & Pellerin 2015Tomazzoli E.R., Pellerin J.M. 2015. Unidades do mapa geológico da ilha de Santa Catarina: as rochas. Geosul, 30(60):225-247.) of the study area (right) indicating the magnetic profiles and magnetic stations over the Joaquina beach.

Figure 2: Vertical gradient (VG) over the Joaquina dune field, drawn in Mirone software (Luis 2007Luis J.F. 2007. Mirone: A multi-purpose tool for exploring grid data. Computers & Geosciences, 33(1):31-41.). Black dots are the magnetic stations.

Figure 3: Upper continuation (at 100 m) of VG over Joaquina dune field, drawn in Mirone software (Luis 2007Luis J.F. 2007. Mirone: A multi-purpose tool for exploring grid data. Computers & Geosciences, 33(1):31-41.). Black dots are the magnetic stations.

Figure 4: Magnetic curves for the Mole profile (A-B). From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). Arrows on the AS curve indicate anomalies clearly related to dykes; BR means below resolution for reliable interpretation.

Figure 5: Magnetic curves for the Gravatá profile (C-D). From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). Arrows on the AS curve indicate anomalies clearly related to dykes; BR means below resolution for reliable interpretation. Shaded area in the TMI curve indicates the profile change in direction.

Figure 6: Magnetic curves for the south profile E-F. From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). Arrows on the AS curve indicate anomalies clearly related to dykes; BR means below resolution for reliable interpretation.

Figure 7: Magnetic curves for the south profile (G-H). From top to bottom: total magnetic intensity (TMI), vertical gradient (VG), analytic signal (AS), total horizontal derivative (THDR), tilt angle (Tilt). The arrow on the AS curve indicate anomaly clearly related to dyke.

Table 1: Magnetic derivatives applied to the 2D profiles.

AS: analytic signal; THDR: total horizontal derivative; T: total magnetic intensity; VG: vertical gradient (Verduzco et al. 2004Verduzco B., Fairhead J.D., Green C.M., Mackenzie C. 2004. New insights into magnetic derivatives for structural mapping. The Leading Edge, 23(2):116-119.).

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[1] *Corresponding author.