Shallow gas accumulation in sediments of the Patos Lagoon, southern Brazil

Weschenfelder, Jair; Corrêa, Iran Carlos Stalliviere; Aliotta, Salvador; Pereira, Carla Mandracio; Vasconcellos, Vinícius Eduardo Bestetti de

doi:10.1590/s0001-37652006000300017

Cited by 27 publications

(37 citation statements)

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“…In Brazil, the presence of these features has been described by various authors such as VITAL and STATTEGGER (1997) in the lowest stretch of the Amazon River; FIGUEIREDO and NITTROUER (1995) and FIGUEIREDO et al (1996) in the Amazon submarine delta and COSTA and FIGUEIREDO (1998) on the Amazon Continental Shelf; BAPTISTA NETO et al (2011) in Rodrigo de Freitas Lagoon -Rio de Janeiro; BENITES et al (2015) in Saco do Mamangua, Rio de Janeiro; BAPTISTA NETO et al (1996), QUARESMA et al (2000) and CATANZARO et al (2004) in Guanabara Bay, Rio de Janeiro; WESCHENFELDER et al (2006) in Patos Lagoon -Rio Grande do Sul associated with low-lying paleotopographical features such as paleo river channels and/or valleys; SCHWARZER et al (2006) in the Rio Açu Canyon and FRAZÃO and VITAL (2007) in the Potengy estuary, both in Rio Grande do Norte; FÉLIX (2012) in the Bertioga Channel, São Paulo;andSOUZA et al (2011), DEMARCO et al (2012), GUESSER et al (2012) andWESCHENFELDER et al (2016) presented preliminary results for the North Bay and the Conceição Lagoon -on the Santa Catarina Coast (Figure 1). In summary, gas-charged sediment and exhaust gases escaping into the water column occur in Brazil on the continental shelf and in rivers, bays and lagoon systems, from north to south, normally associated with sediments rich in organic matter.…”

Section: Introductionmentioning

confidence: 88%

“…Transgressive and regressive events over geological time may have changed this sedimentary environment in various ways, so as to have altered the distribution and quantity of the organic matter available at the site, which could thus provide traps to shape various types of gas (GARCIA-GIL et al, 2002). The sandy pockets may create aquifers and/or gas reservoirs, while the finer, mainly muddy sediments may form aquitards and/or sealing layers (GARCIA-GIL et al, 2002;WESCHENFELDER et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The shallow gas structures occur in various geomorphological features in the form of an Acoustic Blanket (Acoustic Blanking), Acoustic Curtains, Acoustic Columns, Acoustic Turbidity, Turbidity Pinnacles and Intra-sedimentary Plumes, among others types of seismic reflectors (GARCIA-GIL et al, 2002;FRAZÃO;VITAL, 2007;WESCHENFELDER et al, 2006;WESCHENFELDER et al, 2016). The seepage may also occur in the form of Acoustic Plumes and Pockmarks, among others (GARCIA-GIL et al, 2002;FRAZÃO;VITAL, 2007;WESCHENFELDER et al, 2006;WESCHENFELDER et al, 2016). The spatial distribution of the different types of gas accumulation depends on the grain size, porosity and type of sediment and rock in which the gases are trapped (FRAZÃO;VITAL, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

et al. 2016

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This paper presents the spatial distribution of shallow gas structures and classifies them on the basis of two different data sets of CHIRP seismic records, one from the Conceição Lagoon (CL) and the other from North Bay (NB), both on Santa Catarina Island, Southern Brazil. Side scan sonar data from the CL were used to facilitate the understanding. The sub bottom (SB) seismic data were processed and interpreted by means of the SeisPrho software, the side scan sonar (SSS) data by SonarWiz5 software and the spatial extension being measured with the help of GIS. The shallow gas structures were defined in accordance with their shapes in the seismic recordings (echo-character). At the CL, shallow gas accumulations were found in the form of seepages and features presenting shallow gas structures between the surface and 8.20 ms (around 12.3 m). Accumulations of gas were found in the form of Acoustic Blanking with Acoustic Plume, and also Black Shadows. Pockmarks were found on the lagoon floor and associated with gas seepages (average size diameter 0.97 ± 0.19 m and density from 54 to 242 units per 50 m2). In the NB three types of shallow gas features were found in the seismic profile, namely Acoustic Blanking, Turbidity Pinnacles and Intra-sedimentary plumes. The depth varied from the surface to 12.10 ms (around 18.15 m). In both environments, the gas is escaping from the sediment into the water column. The Pockmarks in the CL and the Acoustic Plume features and sediment rich in total sulfur in the NB validate these findings.

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Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

et al. 2016

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“…Estudos recentes têm enfocado diversos aspectos geológicos e evolutivos da região da Lagoa dos Patos, como os processos de sedimentação (Toldo et al, 2000), o fluxo subterrâneo deáguas entre o corpo lagunar e o oceano adjacente (Niencheski et al, 2007), os elementos arquiteturais sismo-deposicionais (Baitelli et al, 2007;Weschenfelder et al, 2005Weschenfelder et al, , 2006, a reconstrução paleoambiental e paleogeográfica (Weschenfelder et al, 2008;Medeanic et al, 2007), entre outros.…”

Section: Area De Estudóunclassified

“…São sistemas de dissecação costeiros que tiveram um papel importante na arquitetura deposicional, distribuição das fácies sedimentares e geração de espaço de acomodação do prisma costeiro da bacia marginal de Pelotas. Registros sísmicos de 3,5 kHz permitiram ainda identificar, de forma pioneira, importantes acumulações de gás raso no substrato da Lagoa dos Patos, principalmente na forma de 'bolsões de gás' e 'gás disseminado', além de outros elementos registrados pela sísmica relacionadosà presença de gás (Weschenfelder et al, 2006).…”

Section: Introductionunclassified

Paleocanais como indicativo de eventos regressivos quaternários do nível do mar no Sul do Brasil

Weschenfelder¹,

Corrêa²,

Toldo³

et al. 2008

Rev. Bras. Geof.

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ABSTRACT. Seismic studies reveals paleochannels that dissected the Rio Grande do Sul coastal zone. Two paleochannels systems were established in the Patos Lagoon area. The channel filling of the younger system is Holocene. It is related to the last marine regression of the Pleistocene, corresponding to the oxygen isotope stage 2. The incision and filling of the older system is related to the previous regressive-transgressive event, corresponding to the oxygen isotope stages 6-5.The paleodrainage paths were connected with those previously recognized on the adjacent continental shelf. Landwards, the paleodrainage lines can be linked with the present courses of the Camaquã and Jacuí rivers. The paleodrainage network recognized on the coastal zone represents a river-shelf system, linking the drainage basin to the depositional settings on the marginal basin, bypassing the continental shelf exposed during a forced regression event. The bypassing discharge of the younger system fed delta systems installed on the shelf edge during the sea level lowstand that lasted until the end of the last glaciation. The last transgression drowned the incised drainage, infilling it and closing the inlets formerly existing between the Patos Lagoon and the Atlantic Ocean. The incised paleodrainage herein considered may have played an important role on the basin-margin architecture, facies distribution and accommodation during the Quaternary sea level oscillations.Keywords: seismic survey, paleodrainage network, Patos Lagoon. RESUMO.Estudos sísmicos revelam paleocanais que dissecaram a região costeira do Rio Grande do Sul. Dois sistemas de paleocanais foram estabelecidos para aárea da Lagoa dos Patos. O preenchimento do sistema de canais mais jovemé Holoceno. Eleé relacionadoàúltima regressão marinha do Pleistoceno, correspondendo ao estágio isotópico 2 do oxigênio. O processo de incisão e preenchimento do sistema mais antigoé relacionado ao evento regressivo-transgressivo anterior, correspondendo aos estágios isotópicos do oxigênio 6-5. As linhas de paleodrenagens foram conectadasàquelas previamente reconhecidas na plataforma continental.A montante, elas podem ser conectadas ao curso atual dos rios Camaquã e Jacuí. As redes de paleodrenagens reconhecidas na zona costeira representam um sistema de ligação entre a bacia de drenagem continental e sítios deposicionais na bacia marginal, dissecando a plataforma continental exposta durante um evento de regressão forçada. A descarga do sistema mais jovem alimentou sistemas deltaicos instalados da borda da plataforma durante o período de mar baixo que perdurou até o final daúltima glaciação. Aúltima transgressão afogou e preencheu os vales costeiros, fechando a ligação entre a Lagoa dos Patos e o Oceano Atlântico. Os sistemas de paleodrenagens aqui considerados devem ter desempenhado um papel importante na arquitetura, distribuição faciológica e no espaço de acomodação da bacia marginal durante as oscilações do nível marinho no Quaternário.Palavras-chave: sísmica de alta resolução, rede de pale...

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Archaeological prospection of the nearshore and intertidal area using ultra‐high resolution marine acoustic techniques: Results from a test study on the Belgian coast at Ostend‐Raversijde

et al. 2017

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The coastal site of Ostend‐Raversijde in Belgium is known for its archaeological artifacts, mainly from Roman and medieval times. In recent years, detailed geophysical and geotechnical investigations have been carried out here to test the efficiency of these techniques for geoarchaeological prospection of the subtidal and intertidal zone. Very high‐resolution 2D subbottom profiling using a parametric echosounder evidenced a highly complex system of paleogullies and tidal channels, some of which can be linked to the medieval peninsula Testerep and the drowned settlement of Walraversijde. For the first time marine seismic and terrestrial electromagnetic induction (EMI) data were fully integrated in the same intertidal area. The parametric echosounder proved a highly effective tool to map the (partly excavated) peat layers and submerged landscape in high detail, even in extremely shallow water. Using a novel multitransducer parametric echosounder (SES‐2000 Quattro), unique 3D imaging of the peat exploitation pattern was possible with unprecedented detail (submeter level). This sets a new standard for shallow water research and opens important new perspectives for geoarchaeological studies in nearshore areas.

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Shallow gas accumulation in sediments of the Patos Lagoon, southern Brazil

Cited by 27 publications

References 9 publications

Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

Paleocanais como indicativo de eventos regressivos quaternários do nível do mar no Sul do Brasil

Archaeological prospection of the nearshore and intertidal area using ultra‐high resolution marine acoustic techniques: Results from a test study on the Belgian coast at Ostend‐Raversijde

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