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| Registros recuperados: 11 | |
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| Orme, Lise C; Crosta, Xavier; Miettinen, Arto; Divine, Dmitry V; Husum, Katrine; Isaksson, Elisabeth; Wacker, Lukas; Mohan, Rahul; Ther, Olivier; Ikehara, Minoru. |
| Centennial and millennial scale variability of Southern Ocean temperature is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variability instead coming mainly from ice core records. Here we present a high-resolution (~ 60 year), diatom-based sea-surface temperature (SST) reconstruction from the western Indian sector of the Southern Ocean that spans the interval 14.2 to 1.0 ka BP (calibrated kiloyears before present). During the late deglaciation, the new SST record shows cool temperatures at 14.2–12.9 ka BP and gradual warming between 12.9–11.6 ka BP in phase with atmospheric temperature evolution. This supports that the temperature of the Southern... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00631/74327/73963.pdf |
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| Xiong, Zhifang; Li, Tiegang; Algeo, Thomas; Doering, Kristin; Frank, Martin; Brzezinski, Mark A.; Chang, Fengming; Opfergelt, Sophie; Crosta, Xavier; Jiang, Fuqing; Wan, Shiming; Zhai, Bin. |
| The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (delta Si-30(E.rex)) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, delta Si-30(E.rex) varies from -1.23 parts per thousand to -0.83 parts per thousand (average -1.04 parts per thousand), a range that is atypical of marine diatom delta Si-30 and that corresponds to the lower limit of reported diatom delta Si-30 values of any age. A binary mixing... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00496/60732/65231.pdf |
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| Pike, Jennifer; Crosta, Xavier; Maddison, Eleanor J.; Stickley, Catherine E.; Denis, Delphine; Barbara, Loic; Renssen, Hans. |
| The available ecological and palaeoecological information for two sea ice-related marine diatoms (Bacillariophyceae), Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jorgensen, suggests that these two species have similar sea surface temperature (SST), sea surface salinity (SSS) and sea ice proximity preferences. From phytoplankton observations, both are described as summer or autumn bloom species, commonly found in low SST waters associated with sea ice, although rarely within the ice. Both species form resting spores (RS) as irradiance decreases, SST falls and SSS increases in response to freezing ice in autumn. Recent work analysing late Quaternary seasonally laminated diatom ooze from coastal Antarctic sites has revealed that... |
| Tipo: Text |
Palavras-chave: East Antarctica; Quaternary; Diatoms; Sea ice. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00220/33092/82663.pdf |
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| Beucher, Charlotte P.; Brzezinski, Mark A.; Crosta, Xavier. |
| The silicic acid leakage hypothesis (SALH) purports that changes in silicon and nitrogen depletion ratios in the glacial Antarctic created a large pool of unused silicic acid that was transported to lower latitudes in subantarctic mode water (SAMW) where it enhanced diatom productivity lowering atmospheric pCO(2). However, increased opal accumulation beneath the sub-Antarctic during glacial times implies significant consumption of silicic acid in subantarctic surface waters that may have significantly diminished or eliminated Si leakage. To test how nutrient dynamics in the sub-Antarctic affected the Si( OH) 4 content of SAMW during the last glacial period, we produced delta(30) Si opal records for cores from the subantarctic and subtropical zones of the... |
| Tipo: Text |
Palavras-chave: Silicon isotope; Silicic acid leakage; Indian sub-Antarctic. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00233/34462/32882.pdf |
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| Denis, Delphine; Crosta, Xavier; Schmidt, Sabine; Carson, Damien S.; Ganeshram, Raja S.; Renssen, Hans; Crespin, Julien; Ther, Olivier; Billy, Isabelle; Giraudeau, Jacques. |
| This study presents the first high-resolution multiproxy investigation of primary productivity ( PP) during the Holocene from the Antarctic continental margins. Micropaleontological and geochemical data from the sediment core MD03-2601, associated to sea ice model outputs, give unprecedented insights into the biological pump of the Antarctic coastal area off Adelie Land in response to climatic changes. Plurimillennial and millennial changes of PP are observed in the study area in response to changes in nutrient availability, stratification, and growing season duration, which are linked to sea ice, upwelling, wind, and glacier dynamics. The precessional cycle seems to be responsible in the PP long-term variations, while forcing factors involved at the... |
| Tipo: Text |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32930/31442.pdf |
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| Panizzo, Virginia; Crespin, Julien; Crosta, Xavier; Shemesh, Aldo; Masse, Guillaume; Yam, Ruth; Mattielli, Nadine; Cardinal, Damien. |
| Combined high-resolution Holocene δ30Sidiat and δ13Cdiat paleorecords are presented from the Seasonal Ice Zone, East Antarctica. Both data sets reflect periods of increased nutrient utilization by diatoms during the Hypsithermal period (circa 7800 to 3500 calendar years (cal years) B.P.), coincident with a higher abundance of open water diatom species (Fragilariopsis kerguelensis), increased biogenic silica productivity (%BSi), and higher regional summer temperatures. The Neoglacial period (after circa 3500 cal years B.P.) is reflected by an increase in sea ice indicative species (Fragilariopsis curta and Fragilariopsis cylindrus, up to 50%) along with a decrease in %BSi and δ13Cdiat (< −18‰ to −23‰). However, over this period, δ30Sidiat data show an... |
| Tipo: Text |
Palavras-chave: Diatoms; Silicon isotopes; Diatom bound carbon isotopes; Seasonal ice zone; Holocene; Southern Ocean. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40157/39098.pdf |
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| Thomas, Elizabeh R; Allen, Claire S; Etourneau, Johan; King, Amy Cf; Severi, Mirko; Winton, V. Holly L.; Mueller, Juliane; Crosta, Xavier; Peck, Victoria L.. |
| Dramatic changes in sea ice have been observed in both poles in recent decades. However, the observational period for sea ice is short, and the climate models tasked with predicting future change in sea ice struggle to capture the current Antarctic trends. Paleoclimate archives, from marine sedimentary records and coastal Antarctic ice cores, provide a means of understanding sea ice variability and its drivers over decadal to centennial timescales. In this study, we collate published records of Antarctic sea ice over the past 2000 years (2 ka). We evaluate the current proxies and explore the potential of combining marine and ice core records to produce multi-archive reconstructions. Despite identifying 92 sea ice reconstructions, the spatial and temporal... |
| Tipo: Text |
Palavras-chave: Sea ice; Antarctica; Paleoclimate; Ice cores; Marine sediments. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00595/70709/68916.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... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37669/36859.pdf |
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| Mackintosh, Andrew N.; Verleyen, Elie; O'Brien, Philip E.; White, Duanne A.; Jones, R. Selwyn; Mckay, Robert; Dunbar, Robert; Gore, Damian B.; Fink, David; Post, Alexandra L.; Miura, Hideki; Leventer, Amy; Goodwin, Ian; Hodgson, Dominic A.; Lilly, Katherine; Crosta, Xavier; Golledge, Nicholas R.; Wagner, Bernd; Berg, Sonja; Van Ommen, Tas; Zwartz, Dan; Roberts, Stephen J.; Vyverman, Wim; Masse, Guillaume. |
| The East Antarctic Ice Sheet (EAIS) is the largest continental ice mass on Earth, and documenting its evolution since the Last Glacial Maximum (LGM) is important for understanding its present-day and future behaviour. As part of a community effort, we review geological evidence from East Antarctica that constrains the ice sheet history throughout this period (similar to 30,000 years ago to present). This includes terrestrial cosmogenic nuclide dates from previously glaciated regions, C-14 chronologies from glacial and post-glacial deposits onshore and on the continental shelf, and ice sheet thickness changes inferred from ice cores and continental-scale ice sheet models. We also include new C-14 dates from the George V Land Terre Adelie Coast shelf. We... |
| Tipo: Text |
Palavras-chave: Antarctica; Last Glacial Maximum; Ice sheet; Sea level rise. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40085/39171.pdf |
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| Campagne, Philippine; Crosta, Xavier; Schmidt, Sabine; Houssais, Marie Noelle; Ther, Olivier; Masse, Guillaume. |
| Diatoms account for a large proportion of primary productivity in Antarctic coastal and continental shelf zones. Diatoms, which have been used for a long time to infer past sea surface conditions in the Southern Ocean, have recently been associated with diatom-specific biomarkers (highly branched isoprenoids, HBI). Our study is one of the few sedimentary research projects on diatom ecology and associated biomarkers in the Antarctic seasonal sea ice zone. To date, the Adelie Land region has received little attention, despite evidence for the presence of high accumulation of laminated sediment, allowing for finer climate reconstructions and sedimentary process studies. Here we provide a sequence of seasonally to annually laminated diatomaceous sediment from... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53279/54324.pdf |
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| Bouttes, Nathaelle; Swingedouw, Didier; Roche, Didier M.; Sanchez-goni, Maria F.; Crosta, Xavier. |
| Atmospheric CO2 levels during interglacials prior to the Mid-Brunhes Event (MBE, similar to 430 kaBP) were around 40 ppm lower than after the MBE. The reasons for this difference remain unclear. A recent hypothesis proposed that changes in oceanic circulation, in response to different external forcings before and after the MBE, might have increased the ocean carbon storage in pre-MBE interglacials, thus lowering atmospheric CO2. Nevertheless, no quantitative estimate of this hypothesis has been produced up to now. Here we use an intermediate complexity model including the carbon cycle to evaluate the response of the carbon reservoirs in the atmosphere, ocean and land in response to the changes of orbital forcings, ice sheet configurations and atmospheric... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00497/60821/65114.pdf |
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| Registros recuperados: 11 | |
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