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| Lattaud, Julie; Lo, Li; Zeeden, Christian; Liu, Ya-jun; Song, Sheng-rong; Van Der Meer, Marcel T.j.; Sinninghe Damsté, Jaap S.; Schouten, Stefan. |
| Long-chain diols have been detected in a wide range of environments and have been used to reconstruct past environmental changes, however only a few long-term records exist to date. Here we reconstructed past environmental changes in the central Sea of Okhotsk over the last 1.5 million years, covering the Mid-Pleistocene Transition (MPT). Sea surface temperatures (SST) reconstructed using the Long-Chain Diol Index (LDI) reflects glacial/interglacial changes. However, when compared with other organic paleothermometers (Uk’37 and TEXL86) the LDI-SST is lower during interglacials and similar or higher during glacials, possibly suggesting a shift of diol production season during interglacials. The LDI-SST does not change in periodicity around the MPT as... |
| Tipo: Text |
Palavras-chave: Sea of Okhotsk; Mid-Pleistocene Transition; LDI; TEX86; U-37(K)'; Biogenic opal; Long-chain diols. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00489/60060/63342.pdf |
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| Van Maldegem, Lennart M.; Sansjofre, Pierre; Weijers, Johan W. H.; Wolkenstein, Klaus; Strother, Paul K.; Woermer, Lars; Hefter, Jens; Nettersheim, Benjamin J.; Hoshino, Yosuke; Schouten, Stefan; Damste, Jaap S. Sinninghe; Nath, Nilamoni; Griesinger, Christian; Kuznetsov, Nikolay B.; Elie, Marcel; Elvert, Marcus; Tegelaar, Erik; Gleixner, Gerd; Hallmann, Christian. |
| Eukaryotic algae rose to ecological relevance after the Neoproterozoic Snowball Earth glaciations, but the causes for this consequential evolutionary transition remain enigmatic. Cap carbonates were globally deposited directly after these glaciations, but they are usually organic barren or thermally overprinted. Here we show that uniquely-preserved cap dolostones of the Araras Group contain exceptional abundances of a newly identified biomarker: 25,28-bisnorgammacerane. Its secular occurrence, carbon isotope systematics and co-occurrence with other demethylated terpenoids suggest a mechanistic connection to extensive microbial degradation of ciliate-derived biomass in bacterially dominated ecosystems. Declining 25,28-bisnorgammacerane concentrations, and a... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74951/76030.pdf |
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| Lopes Dos Santos, Raquel A.; Spooner, Michelle I.; Barrows, Timothy T.; De Deckker, Patrick; Damste, Jaap S. Sinninghe; Schouten, Stefan. |
| Several proxies have been developed to reconstruct past sea surface temperature (SST), but different proxies may reflect temperatures of different seasons and each proxy is characterized by certain uncertainties. Therefore, a multiproxy approach is preferred to precisely reconstruct SST. Here, we reconstruct SST of the ocean offshore southeastern Australia (Murray Canyons area) for the last ~135 ka using three independent organic proxies (TEXH86 based on glycerol dialkyl glycerol tetraethers (GDGTs), UK'37 based on alkenones, and LDI based on long-chain diols) in addition to foraminiferal faunal assemblages. The organic proxy records show similar trends, with the highest temperature (21°C for UK'37 and TEXH86, and 25°C for LDI) during the last interglacial... |
| Tipo: Text |
Palavras-chave: Sea surface temperature; LDI index; TEX86H index; U-37(K') index; Foraminiferal assemblages; SE Australia. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00246/35763/34274.pdf |
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| Blanchet, Cécile L; Tjallingii, Rik; Schleicher, Anja M; Schouten, Stefan; Frank, Martin; Brauer, Achim. |
| 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 the changes in seawater oxygen levels in the recent geological past. Our study is based on three sediment cores spanning the last 10 thousand years (10 kyr BP) and located on a bathymetric transect offshore 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... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00653/76539/77636.pdf |
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| Kim, Jung-hyun; Crosta, Xavier; Willmott, Veronica; Renssen, Hans; Bonnin, Jerome; Helmke, Peer; Schouten, Stefan; Damste, Jaap S. Sinninghe. |
| We reconstructed subsurface (similar to 45-200 m water depth) temperature variability in the eastern Antarctic continental margin during the late Holocene, using an archaeal lipid-based temperature proxy (TEX86 L). Our results reveal that subsurface temperature changes were probably positively coupled to the variability of warmer, nutrient-rich Modified Circumpolar Deep Water (MCDW, deep water of the Antarctic circumpolar current) intrusion onto the continental shelf. The TEX86 L record, in combination with previously published climatic records, indicates that this coupling was probably related to the thermohaline circulation, seasonal variability in sea ice extent, sea temperature, and wind associated with high frequency climate dynamics at low-latitudes... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37669/36859.pdf |
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| Kaiser, Jerome; Schouten, Stefan; Kilian, Rolf; Arz, Helge W.; Lamy, Frank; Damste, Jaap S. Sinninghe. |
| Proxies based on glycerol dialkyl glycerol tetraether (GDGT) lipids from archaea [isoprenoid GDGTs] and bacteria [branched (br) GDGTs] in 33 surface sediments from marine, fjord and lake systems between 25°S and 50°S in Chile were analyzed. The regional TEXH86 calibration obtained from the marine and fjord sediments and mean annual surface temperature (T = 59.6 × TEXH86 + 33.0; r2 0.9; n = 23) is statistically identical to the global ocean calibration based on suspended particulate material in terms of slope, but not in terms of intercept. The regional surface and subsurface TEXH86 calibrations were statistically different from the existing global ocean core top calibrations. The TEX86 calibration model based on most of the relatively large lakes studied... |
| Tipo: Text |
Palavras-chave: GDGT; TEX86; BIT; MBT '; CBT; Calibration; Marine; Fjord; Lake; Chile. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00294/40524/39313.pdf |
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| Castaneda, Isla S.; Caley, Thibaut; Dupont, Lydie; Kim, Jung-hyun; Malaize, Bruno; Schouten, Stefan. |
| In this study we investigate Pleistocene vegetation and climate change in southern East Africa by examining plant leaf waxes in a marine sediment core that receives terrestrial runoff from the Limpopo River. The plant leaf wax records are compared to a multi-proxy sea surface temperature (SST) record and pollen assemblage data from the same site. We find that Indian Ocean SST variability, driven by high-latitude obliquity, exerted a strong control on the vegetation of southern East Africa during the past 800,000 yr. Interglacial periods were characterized by relatively wetter and warmer conditions, increased contributions of C3 vegetation, and higher SST, whereas glacial periods were marked by cooler and arid conditions, increased contributions of C4... |
| Tipo: Text |
Palavras-chave: Vegetation; Africa; N-alkane; Pollen; Subtropical Front; Mid-Brunhes. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00345/45601/45215.pdf |
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| Jaeschke, Andrea; Ziegler, Martin; Hopmans, Ellen C.; Reichart, Gert-jan; Lourens, Lucas J.; Schouten, Stefan; Damste, Jaap S. Sinninghe. |
| Anaerobic ammonium oxidation (anammox) has been recognized as an important process converting fixed nitrogen to N(2) in many marine environments, thereby having a major impact on the present-day marine nitrogen cycle. However, essentially nothing is known about the importance of anammox in past marine nitrogen cycles. In this study, we analyzed the distribution of fossil ladderane lipids, derived from bacteria performing anammox, in a sediment core from the northern Arabian Sea. Concentrations of ladderane lipids varied between 0.3 and 5.3 ng g(-1) sediment during the past 140 ka, with high values observed during the Holocene, intervals during the last glacial, and during the penultimate interglacial. Maxima in ladderane lipid abundances correlate with... |
| Tipo: Text |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32942/31436.pdf |
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| Byrne, Nathalie; Strous, Marc; Crepeau, Valentin; Kartal, Boran; Birrien, Jean-louis; Schmid, Markus; Lesongeur, Francoise; Schouten, Stefan; Jaeschke, Andrea; Jetten, Mike; Prieur, Daniel; Godfroy, Anne. |
| Recent studies indicate that ammonia is an important electron donor for the oxidation of fixed nitrogen, both in the marine water column and sediments. This process, known as anammox, has so far only been observed in a large range of temperature habitats. The present study investigated the role of anammox in hydrothermal settings. During three oceanographic expeditions to the Mid-Atlantic Ridge, hydrothermal samples were collected from five vent sites, at depths ranging from 750 to 3650m from cold to hot habitats. Evidence for the occurrence of anammox in these particular habitats was demonstrated by concurrent surveys, including the amplification of 16S rRNA gene sequences related to known anammox bacteria, ladderanes lipids analysis and measurement of a... |
| Tipo: Text |
Palavras-chave: Hydrothermal vent; Ladderanes; 16S rRNA; Activity; Micro organisms; Anammox. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6921.pdf |
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