Shallow gas occurrence in a Brazilian ria (Saco do Mamangua, Rio de Janeiro) inferred from high-resolution seismic data

Autor(es)

Benites, Mariana ^[1] ; Alves, Daniel Pavani ^[1] ; Maly, Mascimiliano de los Santos ^[1] ; Jovane, Luigi ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Oceanog, BR-05508120 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: CONTINENTAL SHELF RESEARCH; v. 108, p. 89-96, OCT 1 2015.
• Citações Web of Science: 7

Resumo

Semi-enclosed areas, such as rias, offer low-energy sedimentary conditions, which allow the necessary environment for the deposition of clays and organic-rich deposits that generate gas through methanogenic bacteria. In Saco do Mamangua (Rio de Janeiro, Brazil), acoustic data from low frequency echo sounder and high-resolution seismic-reflection data from chirp sonar and boomer from three surveys February 2009 and January and June 2014 - enabled for the first time the identification of acoustic disturbances related to gas occurrences. Saco do Mamangua hosts shallow gas accumulation throughout its entire area, expressed as acoustic turbidity, enhanced reflections or acoustic blanking, intra-sedimentary plumes and acoustic plumes. However, gas occurrence evidence decreases towards the open ocean. A lithological control occurs on the sealing layer in the inner area, whereas the smaller gas occurrence in the outer area can be due to (1) absence of a sealing layer and/or (2) the re-oxidizing of methane as more oxygenated waters are available. We propose a sequence stratigraphic model in which the gas formation is Holocene or either pre-Holocene age. (C) 2015 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 11/22018-3 - Avaliação da produtividade primária marinha através do estudo das bactérias magnetotáticas em sedimentos
• Beneficiário: Luigi Jovane
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Jovens Pesquisadores