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Tectonic framework of the Barra de Sao Joao Graben, Campos Basin, Brazil; insights from gravity data interpretation

Leandro B. Adriano, Paulo T. L. Menezes and Alan S. Cunha
Tectonic framework of the Barra de Sao Joao Graben, Campos Basin, Brazil; insights from gravity data interpretation (in Interpretation and integration of gravity and magnetic data, Ran Zhang (prefacer), Rao Yalamanchili (prefacer) and Alan Aitken (prefacer))
Interpretation (Tulsa) (November 2014) 2 (4): SJ65-SJ74

Abstract

The Barra de Sao Joao Graben (BSJG), shallow water Campos Basin, is part of the Cenozoic rift system that runs parallel to the Brazilian continental margin. This system was formed in an event that caused the reactivation of the main Precambrian shear zones of southeastern Brazil in the Paleocene. We proposed a new structural framework of BSJG based on gravity data interpretation. Magnetic data, one available 2D seismic line, and a density well-log of a nearby well were used as constraints to our interpretation. To estimate the top of the basement structure, we separated the gravity effects of deep sources from the shallow basement (residual anomaly). Then, we performed a 2D modeling exercise, in which we kept fixed the basement topography and the density of the sediments, to estimate the density of the basement rocks. Next, we inverted the residual anomaly to recover the depth to the top of the basement. This interpretation strategy allowed the identification of a complex structural framework with three main fault systems: a northeast-southwest-trending normal fault system, a northwest-southeast-trending transfer fault system, and an east-west-trending transfer fault system. These trends divided the graben into several internal highs and lows. Our interpretation was corroborated by the magnetic anomalies. The existence of ultradense and strongly magnetized elongated bodies in the basement was interpreted as ophiolite bodies that were probably obducted by the time of the shutdown of the Proterozoic Adamastor Ocean.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 2
Serial Issue: 4
Title: Tectonic framework of the Barra de Sao Joao Graben, Campos Basin, Brazil; insights from gravity data interpretation
Title: Interpretation and integration of gravity and magnetic data
Author(s): Adriano, Leandro B.Menezes, Paulo T. L.Cunha, Alan S.
Author(s): Zhang, Ranprefacer
Author(s): Yalamanchili, Raoprefacer
Author(s): Aitken, Alanprefacer
Affiliation: CGG Airborne, LASA Prospeccoes, Rio de Janeiro, Brazil
Affiliation: BHP Billiton, London, United Kingdom
Pages: SJ65-SJ74
Published: 20141101
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 31
Accession Number: 2015-007670
Categories: Structural geologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: sects., geol. sketch maps
S23°19'60" - S21°00'00", W44°00'00" - W40°00'00"
Secondary Affiliation: CGG GravMag Solutions, USA, United StatesUniversity of Western Australia, AUS, AustraliaUniversidade do Estado do Rio de Janeiro, BRA, Brazil
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201504
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