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| Bayon, Germain; Dupre, Stephanie; Ponzevera, Emmanuel; Etoubleau, Joel; Cheron, Sandrine; Pierre, Catherine; Mascle, Jean; Boetius, Antje; De Lange, Gert J.. |
| Marine sediments at ocean margins vent substantial amounts of methane(1,2). Microbial oxidation of the methane released can trigger the precipitation of carbonate within sediments and support a broad diversity of seafloor ecosystems(3,4). The factors controlling microbial activity and carbonate precipitation associated with the seepage of submarine fluid over geological time remain poorly constrained. Here, we characterize the petrology and geochemistry of rocks sampled from metre-size build-ups of methane-derived carbonate chimneys located at the Amon mud volcano on the Nile deep-sea fan. We find that these carbonates comprise porous structures composed of aggregated spherules of aragonite, and closely resemble microbial carbonate reefs forming at present... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00156/26734/24854.pdf |
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| Omoregie, Enoma O.; Niemann, Helge; Mastalerz, Vincent; De Lange, Gert J.; Stadnitskaia, Alina; Mascle, Jean; Foucher, Jean-paul; Boetius, Antje. |
| The Eastern Mediterranean hosts a variety of active cold seep systems, such as gas chimneys, mud volcanoes and pockmarks, in water depths of 500 to 3200 m. As part of the NAUTINIL expedition in 2003, the sediments of cold seeps on the Nile Deep Sea Fan (NDSF) were sampled for the first time for biogeochemical and microbiological analyses. Here we compare rates of the anaerobic oxidation of methane (AOM) and sulfate reduction (SR) as well as the microbial community structure of a variety of cold seep systems including mud volcanoes, pockmarks and brine seeps. Our results revealed strong differences in microbial activity among the different seep systems of the Eastern, Central and Western provinces of the NDSF, as well as the Olimpi field (Central... |
| Tipo: Text |
Palavras-chave: Methane oxidation; Sulfate reduction; Archaea; Cold seeps; Mud volcano; Pockmarks; Nile Deep Sea Fan. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00000/11087/7910.pdf |
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| Maiorano, Patrizia; Tarantino, Francesca; Marino, Maria; De Lange, Gert J.. |
| Quantitative analyses on calcareous nannofossil assemblages on high temporal resolution (600-800 years) have been carried out from Core KC01B in the Ionian Sea (Eastern Mediterranean) throughout Marine Isotope Stage (MIS) 13-9, between 500 and 300 ka. This is an interval of considerable climate changes, known as the Mid-Brunhes event, which includes MIS 11, considered as a possible analogue for future interglacial conditions. In the Mediterranean core, the interval is characterized by the dominance of Gephyrocapsa spp., as also known from ocean records. Calcareous nannofossil abundance fluctuations have been interpreted in terms of modification of sea surface primary productivity/water stratification and temperature. Specifically, the increase in abundance... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00181/29194/27593.pdf |
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| Wu, Jiawang; Filippidi, Amalia; Davies, Gareth R.; De Lange, Gert J.. |
| Organic-rich sapropel sediments were repeatedly deposited in the eastern Mediterranean Sea (EMS), in response to insolation-driven freshwater forcing. However, the exact freshwater sources and causal associated paleoclimate-related processes remain unresolved. Sapropel S5, formed during the insolation maximum of the last interglacial, is one of the most intensely developed sapropels of the Late-Quaternary. Here, detrital sediments of sapropel S5 obtained from 8 cores, together with 13 EMS surface samples, are analyzed for major elements, rare earth elements, and Sr and Nd isotopes. This permits a basin-wide investigation of the source and distribution of river-borne material to the EMS for sapropel S5, and its comparison to the present-day and the Holocene... |
| Tipo: Text |
Palavras-chave: Sapropel S5; Eastern Mediterranean Sea; Provenance; Radiogenic isotopes; Major elements; Rare earth elements. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00435/54623/56024.pdf |
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| Hennekam, Rick; Jilbert, Tom; Schnetger, Bernhard; De Lange, Gert J.. |
| We present high-resolution records for oxygen isotopes of the planktic foraminifer Globigerinoides ruber (delta O-18(ruber)) and bulk sediment inorganic geochemistry for Holocene-age sediments from the southeast Mediterranean. Our delta O-18(ruber) record appears to be dominated by Nile discharge rather than basin-scale salinity/temperature changes. Nile discharge was enhanced in the early to middle Holocene relative to today. The timing of the long-term maximum in Nile discharge during the early Holocene corresponds to the timing of maximum intensity of the Indian Ocean-influenced Southwest Indian summer monsoon (SIM). This coincidence suggests a major influence of an Indian Ocean moisture source on Nile discharge in the early to middle Holocene, while,... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40148/39104.pdf |
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| Reitz, Anja; Thomson, John; De Lange, Gert J.; Hensen, Christian. |
| [ 1] The residual dark unit of the most recent eastern Mediterranean sapropel (S1) is usually overlain by sediments with enhanced concentrations of MnO(x) in two separated layers. The variability and magnitude of the Mn enrichment at different locations and water depths indicate that Mn must have been added preferentially to sediments at intermediate ( 1 - 2 km) water depths. We propose a two-stage mechanism for the Mn enrichment that involves decreasing oxygenation with increasing water depth. This mechanism involves the loss of reduced Mn(2+) from the deepest sediments (> 2 km water depth) into overlying anoxic waters and a variable gain of MnOx in sediments in contact with oxygenated waters at shallower depth. In the S1 unit that receives the extra... |
| Tipo: Text |
Palavras-chave: Manganese; Sapropel S1; Eastern Mediterranean; Molybdenum; Lithium. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34529/33426.pdf |
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