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| Gay, Aurelien; Lopez, M; Ondreas, Helene; Charlou, Jean-luc; Sermondadaz, G; Cochonat, Pierre. |
| The origin of the cold fluid venting from a Giant Pockmark within the Lower Congo Basin has been elucidated based upon results of precise mapping, submersible dives, gravity coring and isotopic analyses realized under a TOTAL-IFREMER cooperative project (ZAIANGO and BIOZAIRE projects). During four dives of the IFREMER ROV-Victor 6000, the bottom was filmed, hard and soft samples were lifted from the sediment, and water samples were collected with a CTD-rosette system. The detailed dip map shows that the 800 in wide Giant Pockmark is a composite feature due to the coalescence of multiple 100 in wide depressions that displays a broad range of biological, mineralogical and chemical features on the seafloor, leading to a seafloor anomaly recorded on the... |
| Tipo: Text |
Palavras-chave: BIOZAIRE; ZAIANGO; Palaeochannel; Hydrates; Chemosynthesis; Seafloor facies; Fluid migration; Pockmark. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1114.pdf |
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| Gay, Aurelien; Lopez, M; Cochonat, Pierre; Seranne, M; Levache, D; Sermondadaz, G. |
| Based on high-resolution 3D seismic data sets, we document the subsurface reservoir architecture and organization of a portion of the Oligocene-Miocene stratigraphy within the Congo Basin, offshore southwestern Africa. Within the 3D seismic volume, we have identified four levels of turbiditic palaeochannels, which are separated by low-amplitude continuous reflectors interpreted as hemipelagic sediments. Geochemical analyses on sediment samples taken within overlying seafloor pockmarks reveal the presence of thermogenic gases and oils, suggesting that deep-seated fluids have migrated through both the channel deposits and the impermeable layers between them, forming a conduit to the surface. Deep thermogenic fluids produced within Cretaceous source rocks are... |
| Tipo: Text |
Palavras-chave: Polygonal faults; BSR; Fluid chimneys; Pipes; Hydrates; Turbiditic palaeochannels; Pockmarks; Fluid migration. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1111.pdf |
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| Gay, A; Lopez, M; Cochonat, Pierre; Levache, D; Sermondadaz, G; Seranne, M. |
| Using high quality 3D seismic data within the Lower Congo Basin (LCB), we have identified pockmarks that are aligned above the sinuous belt of a buried turbiditic palaeo-channel, 1000 m beneath the seafloor. Geochemical analyses on cores (GC traces), taken in the centre of four of these pockmarks along this channel, show no clear evidence for migrated oil. But, some features of the GC traces, including elevated baselines (UCM > 34 mu g/g) and a broad molecular weight range of n-alkanes with little odd-even preference, may be interpreted as indicating the presence of thermogenic hydrocarbons in the cores. Seismic profiles show that these pockmarks developed above two-main features representative of pore fluid escape during early compaction: (1) closely... |
| Tipo: Text |
Palavras-chave: Pipes; Seismic chimneys; Polygonal faults; Fluid migration; Turbiditic channels; Pockmarks. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1673.pdf |
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| Olu, Karine. |
| The paper by Gay et al. describes a giant pockmark on the basis of geological and biological data collected during ROV dives. The description of seep communities based on a transect across the pockmark includes some mistakes. Part of the description of the fauna is attributed to Olu-Le Roy et al. (2003) and includes data that have not been presented in this oral communication. An "evolutive model" is proposed, based on these data and on an incorrect interpretation of symbiotic species requirements (classification of methane vs sulfide dependent species). In this note, I would like to point out the mistakes of this paper and express why their model cannot be used to describe the reality of the seabed. |
| Tipo: Text |
Palavras-chave: BIOZAIRE; ZAIANGO; Palaeochannel; Hydrates; Chemosynthesis; Seafloor facies; Fluid migration; Pockmark. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2276.pdf |
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