scholarly journals Authigenic carbonates from methane seeps of the Congo deep-sea fan

2007 ◽  
Vol 27 (2-4) ◽  
pp. 249-257 ◽  
Author(s):  
Catherine Pierre ◽  
Yves Fouquet
Keyword(s):  
Deep Sea ◽  
Methane Seeps ◽  
Authigenic Carbonates ◽  
Sea Fan

Mineralization of vestimentiferan tubes at methane seeps on the Congo deep-sea fan

2009 ◽  
Vol 56 (2) ◽  
pp. 283-293 ◽  
Author(s):  
Antonie Haas ◽  
Crispin T.S. Little ◽  
Heiko Sahling ◽  
Gerhard Bohrmann ◽  
Tobias Himmler ◽  
...  
Keyword(s):  
Deep Sea ◽  
Methane Seeps ◽  
Sea Fan

scholarly journals Authigenic carbonates related to active seepage of methane-rich hot brines at the Cheops mud volcano, Menes caldera (Nile deep-sea fan, eastern Mediterranean Sea)

2014 ◽  
Vol 34 (2-3) ◽  
pp. 253-267 ◽  
Author(s):  
Catherine Pierre ◽  
Germain Bayon ◽  
Marie-Madeleine Blanc-Valleron ◽  
Jean Mascle ◽  
Stéphanie Dupré
Keyword(s):  
Mediterranean Sea ◽  
Deep Sea ◽  
Eastern Mediterranean ◽  
Mud Volcano ◽  
Authigenic Carbonates ◽  
Eastern Mediterranean Sea ◽  
Sea Fan

scholarly journals Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales

2021 ◽  
Vol 17 (3) ◽  
pp. 1025-1050
Author(s):  
Cécile L. Blanchet ◽  
Rik Tjallingii ◽  
Anja M. Schleicher ◽  
Stefan Schouten ◽  
Martin Frank ◽  
...  
Keyword(s):  
Organic Matter ◽  
Primary Productivity ◽  
Deep Sea ◽  
Nile Delta ◽  
Sediment Cores ◽  
Benthic Fauna ◽  
Early Summer ◽  
Authigenic Carbonates ◽  
Terrigenous Input ◽  
Sea Fan

Abstract. Ocean deoxygenation is a rising threat to marine ecosystems and food resources under present climate warming conditions. Organic-rich sapropel layers deposited in the Mediterranean Sea provide a natural laboratory to study the processes that have controlled changes in seawater oxygen levels in the recent geological past. Our study is based on three sediment cores spanning the last 10 000 years and located on a bathymetric transect offshore from the western distributaries of the Nile delta. These cores are partly to continuously laminated in the sections recording sapropel S1, which is indicative of bottom-water anoxia above the western Nile deep-sea fan. We used a combination of microfacies analyses and inorganic and organic geochemical measurements to reconstruct changes in oxygenation conditions at seasonal to millennial timescales. Millimetre-thick laminations are composed of detrital, biogenic and chemogenic sublayers reflecting seasonal successions of sedimentation. Dark layers reflect the deposition of summer floods and two types of light layers correspond to autumn plankton blooms and authigenic carbonates formed in the water column during spring–early summer, respectively. The isotopic signature of the authigenic carbonates suggests permanent anoxic to euxinic bottom waters resulting in high levels of anaerobic remineralization of organic matter and highlights their potential to reconstruct seawater chemistry at times when benthic fauna was absent. Ratios of major elements combined with biomarkers of terrestrial and marine organic matter and redox-sensitive compounds allow changes in terrigenous input, primary productivity and past deoxygenation dynamics on millennial timescales to be tracked. Rapid fluctuations of oxygenation conditions in the upper 700 m water depth occurred above the Nile deep-sea fan between 10 and 6.5 ka BP, while deeper cores recorded more stable anoxic conditions. Synchronous changes in terrigenous input, primary productivity and past oxygenation dynamics after 6.5 ka BP show that runoff-driven eutrophication played a central role in rapid oxygenation changes in the south-eastern Levantine Basin. These findings are further supported by other regional records and reveal time-transgressive changes in oxygenation state driven by rapid changes in primary productivity during a period of long-term deep-water stagnation.

scholarly journals Stratigraphic revision and reconstruction of the deep-sea fan of the Voirons Flysch (Voirons Nappe, Chablais Prealps)

2021 ◽  
Vol 114 (1) ◽  
Author(s):  
Jérémy Ragusa ◽  
Lina Maria Ospina-Ostios ◽  
Pascal Kindler ◽  
Mario Sartori
Keyword(s):  
Deep Sea ◽  
Distal Part ◽  
Accretionary Prism ◽  
Proximal Part ◽  
Late Eocene ◽  
Lithostratigraphic Units ◽  
Stratigraphic Record ◽  
Sea Fan ◽  
Stratigraphic Evolution ◽  
Depositional Setting

AbstractThe Voirons Flysch (Caron in Eclogae Geologicae Helvetiae 69:297–308, 1976), is a flysch sequence aggregated into the sedimentary accretionary prism of the Chablais and Swiss Prealps. Its palaeogeographic location is still debated (South Piemont or Valais realm). We herein present a stratigraphic revision of the westernmost unit of the former Gurnigel Nappe sensu Caron (Eclogae Geologicae Helvetiae 69:297–308, 1976): the Voirons Flysch. This flysch is subdivided into three lithostratigraphic units at the formation level (the Voirons Sandstone, the Vouan Conglomerate, the Boëge Marl), with an additional unit (Bruant Sandstone) of uncertain attribution, ranging from the early Eocene to probably the late Eocene. We further propose a new model of the depositional setting of the deep-sea of the Voirons Flysch based on palaeocurrent directions, the overall geometry and sedimentary features. This model depicts an eastward deflected deep-sea fan. The stratigraphic record of the proximal part of this fan is fairly complete in the Voirons area, whereas its most distal part is only represented by one small exposure of thinly bedded sandstones in the Fenalet quarry. The stratigraphic evolution of the Voirons Flysch shows two major disruptions of the detrital sedimentation at the transition between Voirons Sandstone—Vouan Conglomerate and Vouan Conglomerate—Boëge Marl. The cause of these disturbances has to be constrained in the framework of the palaeogeographic location of the Voirons Flysch.

scholarly journals Sulfur bacteria promote dissolution of authigenic carbonates at marine methane seeps

2021 ◽  
Author(s):  
Dalton J. Leprich ◽  
Beverly E. Flood ◽  
Peter R. Schroedl ◽  
Elizabeth Ricci ◽  
Jeffery J. Marlow ◽  
...  
Keyword(s):  
Carbonate Rocks ◽  
Sulfur Oxidation ◽  
Methane Seeps ◽  
Etch Pits ◽  
Active Dissolution ◽  
Authigenic Carbonates ◽  
Sulfur Bacteria ◽  
Sulfur Oxidizing ◽  
Sulfur Oxidizing Bacteria

AbstractCarbonate rocks at marine methane seeps are commonly colonized by sulfur-oxidizing bacteria that co-occur with etch pits that suggest active dissolution. We show that sulfur-oxidizing bacteria are abundant on the surface of an exemplar seep carbonate collected from Del Mar East Methane Seep Field, USA. We then used bioreactors containing aragonite mineral coupons that simulate certain seep conditions to investigate plausible in situ rates of carbonate dissolution associated with sulfur-oxidizing bacteria. Bioreactors inoculated with a sulfur-oxidizing bacterial strain, Celeribacter baekdonensis LH4, growing on aragonite coupons induced dissolution rates in sulfidic, heterotrophic, and abiotic conditions of 1773.97 (±324.35), 152.81 (±123.27), and 272.99 (±249.96) μmol CaCO3 • cm−2 • yr−1, respectively. Steep gradients in pH were also measured within carbonate-attached biofilms using pH-sensitive fluorophores. Together, these results show that the production of acidic microenvironments in biofilms of sulfur-oxidizing bacteria are capable of dissolving carbonate rocks, even under well-buffered marine conditions. Our results support the hypothesis that authigenic carbonate rock dissolution driven by lithotrophic sulfur-oxidation constitutes a previously unknown carbon flux from the rock reservoir to the ocean and atmosphere.

The ancestral Mississippi drainage archived in the late Wisconsin Mississippi deep-sea fan

Geology ◽  
2016 ◽  
Vol 44 (6) ◽  
pp. 479-482 ◽  
Author(s):  
A. Fildani ◽  
M.P. McKay ◽  
D. Stockli ◽  
J. Clark ◽  
M.L. Dykstra ◽  
...  
Keyword(s):  
Deep Sea ◽  
Sea Fan

scholarly journals Relative Abundance and Diversity of Bacterial Methanotrophs at the Oxic–Anoxic Interface of the Congo Deep-Sea Fan

2017 ◽  
Vol 8 ◽  
Author(s):  
Sandrine Bessette ◽  
Yann Moalic ◽  
Sébastien Gautey ◽  
Françoise Lesongeur ◽  
Anne Godfroy ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Deep Sea ◽  
Abundance And Diversity ◽  
Sea Fan

Two new species of Cossura (Cossuridae, Annelida) from the terminal lobes of the Congo River deep-sea fan

2017 ◽  
Vol 97 (5) ◽  
pp. 881-888
Author(s):  
Anna Zhadan
Keyword(s):  
New Species ◽  
Deep Sea ◽  
Anterior Margin ◽  
Posterior Part ◽  
Entire Body ◽  
Congo River ◽  
Two New Species ◽  
Dark Pigmentation ◽  
Sea Fan ◽  
Scanning Electron

Two new species of Cossura Webster & Benedict, 1887 were found in material collected during sampling from the terminal lobes of the Congo deep-sea fan. They were described using light and scanning electron microscopy. Cossura platypus sp. nov. has 15–17 thoracic chaetigers, a prostomium longer than it is wide, with a widely rounded anterior margin, an abruptly expanded posterior prostomial ring the same length as the peristomium, without a mid-ventral notch, a branchial filament attached to the midlength of chaetiger 3, and a pygidium with three anal cirri. Cossura platypus sp. nov. is similar to C. brunnea Fauchald, 1972 but differs in the shape of the prostomium, which is widely rounded anteriorly in C. platypus sp. nov. and is broadly triangular in C. brunnea; furthermore, C. platypus sp. nov.is uniformly pale, whereas C. brunnea has dark pigmentation. Cossura candida Hartman, 1955 differs from C. platypus sp. nov. in the conical shape of the prostomium and 24–35 thoracic chaetigers. Cossura flabelligera sp. nov. has 16–19 thoracic chaetigers, a conical prostomium, and a branchial filament arising from the posterior part of chaetiger 2; the entire body, including the chaetae, is covered by a thick mucous sheath similar to the tunic of flabelligerids. Cossura flabelligera sp. nov. resembles C. longocirrata Webster & Benedict, 1887 in the position of the branchial filament, the shape of the prostomium, and the number of thoracic chaetigers; it differs in having a thick mucous sheath. This character seems to be unique for the Cossuridae.

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