Vast fields of hydrocarbon-derived carbonate chimneys related to the accretionary wedge/olistostrome of the Gulf of Cádiz

Díaz‐del‐Río, V.; Somoza, Luı́s; Martínez‐Frías, Jesús; Mata, Pilar; Delgado, Antonio; Hernández-Molina, F. Javier; Hernández, Rosario Lunar; Martín-Rubí, Juan Antonio; Maestro, Adolfo; Fernández-Puga, M.C.; León, Ricardo; Llave, Estefanía; Medialdea, Teresa; Vázquez, Juan Tomás

doi:10.1016/s0025-3227(02)00687-4

Cited by 201 publications

(106 citation statements)

References 33 publications

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“…Reducing conditions a few centimetres below the water-sediment interface in the area have been reported by numerous authors (e.g. Díaz-del-RÍo et al, 2003;Somoza et al, 2003;Stadnitskaia et al, 2006Stadnitskaia et al, , 2008. In the textural analysis the presence of carbonates (siderite to rhodochrosite) was observed in the nuclei of nodules as micro-sparitic cements formed within fine-grained c1astic sediments.…”

Section: Stage One: the Diagenetic Processsupporting

confidence: 58%

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

et al. 2012

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Section: Stage One: the Diagenetic Processsupporting

confidence: 58%

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

et al. 2012

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“…and other thiotrophic organisms (Boetius and Suess, 2004 and literature therein). Furthermore, methane venting at various cold seeps is associated with the precipitation of MDACs which often contain lipid biomarkers of AOM communities (Bohrmann et al, 1998;Diaz-del-Rio et al, 2003;Hovland et al, , 1987Michaelis et al, 2002;Peckmann et al, 1999;Roberts and Aharon, 1994;Thiel et al, 2001). The phylogenetic origin of methanotrophic communities has been determined using combinations of lipid analysis and 16S rDNA methods in several methane seep environments (Boetius et al, 2000;Elvert et al, 1999;Hinrichs et al, 1999;Hoehler and Alperin, 1996;Knittel et al, , 2005Michaelis et al, 2002;Orphan et al, 2001b).…”

Section: Introductionmentioning

confidence: 99%

Methane emission and consumption at a North Sea gas seep (Tommeliten area)

et al. 2005

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Abstract. The Tommeliten seepage area is part of the Greater Ekofisk area, which is situated above the Tommeliten Delta salt diapir in the central North Sea (56 • 29.90 N, 2 • 59.80 E, Norwegian Block 1/9, 75 m water depth). Here, cracks in a buried marl horizon allow methane to migrate into overlying clay-silt and sandy sediments. Hydroacoustic sediment echosounding showed several venting spots coinciding with the apex of marl domes where methane is released into the water column and potentially to the atmosphere. In the vicinity of the gas seeps, sea floor observations showed small mats of giant sulphide-oxidizing bacteria above patches of black sediments as well as carbonate crusts, which are exposed 10 to 50 cm above seafloor forming small reefs. These Methane-Derived Authigenic Carbonates (MDACs) contain 13 C-depleted, archaeal lipids indicating previous gas seepage and AOM activity. High amounts of sn2-hydroxyarchaeol relative to archaeol and low abundances of biphytanes in the crusts give evidence that ANaerobic MEthane-oxidising archaea (ANME) of the phylogenetic cluster ANME-2 were the potential mediators of Anaerobic Oxidation of Methane (AOM) at the time of carbonate formation. Small pieces of MDACs were also found subsurface at about 1.7 m sediment depth, associated with the AOM zone. This zone is characterized by elevated AOM and Sulphate Reduction (SR) rates, increased concentrations of 13 C-depleted tetraether derived biphytanes, and specific bacterial Fatty Acids (FA). Further biomarker and 16S rDNA based analyses of this horizon give evidence that AOM is mediated by archaea belongCorrespondence to: H. Niemann (hniemann@mpi-bremen.de) ing to the ANME-1b group and Sulphate Reducing Bacteria (SRB) most likely belonging to the Seep-SRB1 cluster. The zone of active methane consumption was restricted to a distinct horizon of about 20 cm. Concentrations of 13 Cdepleted lipid biomarkers (e.g. 500 ng g-dw −1 biphythanes, 140 ng g-dw −1 fatty acid ai-C 15:0 ), cell numbers (1.5×10 8 cells cm −3 ), AOM and SR rates (3 nmol cm −3 d −1 ) in the Tommeliten AOM zone are 2-3 orders of magnitude lower compared to AOM zones of highly active deep water cold seeps such as Hydrate Ridge or the Gulf of Mexico.

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“…It remains uncertain whether they recorded the signal of water released from gas hydrate dissociation or isotopically heavy glacial ocean water. Since aragonite tends to form near the sedimentseawater interface [6][7][8]21], hence when fluids emitted from the seafloor, they are strongly diluted and therefore the signal of venting fluid recorded in aragonite would be much weaker compared to the chimney-like carbonates that precipitated around the fluid conduits below the sedimentseawater interface. In this paper, we focus on the chimneylike carbonates based on these previous studies.…”

Section: South China Sea Seep Carbonate Chimneys Carbon and Oxygen mentioning

confidence: 99%

“…They are different from normal marine carbonates in carbon source and formation mechanism. According to their environment of formation, seep carbonates can be classified into two types [4][5][6][7]. One type forms at the sediment-seawater interface in contacts with bottom seawater such as chemoherm carbonates and carbonate pavements.…”

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Origin and nature of cold seep in northeastern Dongsha area, South China Sea: Evidence from chimney-like seep carbonates

2013

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The occurrence of seep carbonates is one of the characteristic features for cold seep sites at continental margins. The carbonates documented the venting history of methane-rich fluid. Compared to the chemoherm carbonates and carbonate pavements which formed on the sediment-water interface, chimney-like seep carbonates precipitated around fluid conduits below the sediment-water interface therefore better recording information of the past fluid flow and composition. Here the chimney-like seep carbonate samples from the northeastern Dongsha area of the South China Sea were studied to understand the origin and nature of the venting fluids and their potential relationship with gas hydrate deposits underneath the seafloor. Based on the occurrence, morphology, petrology, mineralogy and C-and O-isotope compositions, combined with present and past bottom water temperatures and the timing of methane release events, the oxygen isotopic fractionation between calcite and water were used to estimate the equilibrium δ18 O values of the precipitating fluids. The δ 13 C values ranging from −56.33‰ to −42.70‰ V-PDB and thus clearly show that the studied chimneys were mainly derived from biogenic methane oxidation. The calculated equilibrium δ 18 O values of the precipitating fluids ranged from 1.9‰  0.3‰ to 0.6‰  0.3‰ V-SMOW, with an average of 1.4‰  0.3‰ V-SMOW which is heavier than those of seawater even at the last glacial maximum. It is considered that the formation of chimney-like carbonates was closely related to methane hydrate dissociation in the area. The methane hydrates contributed as much as 45.7% of water to the venting fluids. It is suggested that the climate and environmental changes (e.g. sea-level lowering, down-cutting canyons and mass wasting) are the major mechanisms maybe responsible for the destabilization of methane hydrates in the study area. The extensive occurrence of seep carbonates indicates that a large amount of the methane released from methane hydrate dissociation has been effectively captured and sequestered by microbial anaerobic oxidation of methane (AOM) before it escapes into the water column.South China Sea, seep carbonate chimneys, carbon and oxygen isotopes, gas hydrate deposits, methane-rich fluids Citation:

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Vast fields of hydrocarbon-derived carbonate chimneys related to the accretionary wedge/olistostrome of the Gulf of Cádiz

Cited by 201 publications

References 33 publications

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

Methane emission and consumption at a North Sea gas seep (Tommeliten area)

Origin and nature of cold seep in northeastern Dongsha area, South China Sea: Evidence from chimney-like seep carbonates

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