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| Abelmann, Andrea; Gersonde, Rainer; Knorr, Gregor; Zhang, Xu; Chapligin, Bernhard; Maier, Edith; Esper, Oliver; Friedrichsen, Hans; Lohmann, Gerrit; Meyer, Hanno; Tiedemann, Ralf. |
| Reduced surface-deep ocean exchange and enhanced nutrient consumption by phytoplankton in the Southern Ocean have been linked to lower glacial atmospheric CO2. However, identification of the biological and physical conditions involved and the related processes remains incomplete. Here we specify Southern Ocean surface-subsurface contrasts using a new tool, the combined oxygen and silicon isotope measurement of diatom and radiolarian opal, in combination with numerical simulations. Our data do not indicate a permanent glacial halocline related to melt water from icebergs. Corroborated by numerical simulations, we find that glacial surface stratification was variable and linked to seasonal sea-ice changes. During glacial spring-summer, the mixed layer was... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00497/60842/64285.pdf |
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| Serno, Sascha; Winckler, Gisela; Anderson, Robert F.; Hayes, Christopher T.; Mcgee, David; Machalett, Bjoern; Ren, Haojia; Straub, Susanne M.; Gersonde, Rainer; Haug, Gerald H.. |
| Eolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high nutrient-low chlorophyll status of the Subarctic North Pacific. We map the spatial distribution of dust input using three different geochemical tracers of eolian dust, He-4, Th-232 and rare earth elements, in combination with grain size distribution data, from a set of core-top sediments covering the entire Subarctic North Pacific. Using the suite of geochemical proxies to fingerprint different lithogenic components, we deconvolve eolian dust input from other lithogenic inputs such as volcanic ash, ice-rafted debris, riverine and hemipelagic input. While the open ocean sites far away from... |
| Tipo: Text |
Palavras-chave: Eolian dust; Subarctic North Pacific; INOPEX; Helium-4; Th-232; REE. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00291/40196/38719.pdf |
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| Basak, Chandranath; Froellje, Henning; Lamy, Frank; Gersonde, Rainer; Benz, Verena; Anderson, Robert F.; Molina-kescher, Mario; Pahnke, Katharina. |
| Stratification of the deep Southern Ocean during the Last Glacial Maximum is thought to have facilitated carbon storage and subsequent release during the deglaciation as stratification broke down, contributing to atmospheric CO2 rise. Here, we present neodymium isotope evidence from deep to abyssal waters in the South Pacific that confirms stratification of the deepwater column during the Last Glacial Maximum. The results indicate a glacial northward expansion of Ross Sea Bottom Water and a Southern Hemisphere climate trigger for the deglacial breakup of deep stratification. It highlights the important role of abyssal waters in sustaining a deep glacial carbon reservoir and Southern Hemisphere climate change as a prerequisite for the destabilization of the... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00497/60822/64608.pdf |
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| Ho, Sze Ling; Mollenhauer, Gesine; Lamy, Frank; Martinez-garcia, Alfredo; Mohtadi, Mahyar; Gersonde, Rainer; Hebbeln, Dierk; Nunez-ricardo, Samuel; Rosell-mele, Antoni; Tiedemann, Ralf. |
| In spite of the important role played by the Southern Ocean in global climate, the few existing paleoceanographic records in the east Pacific sector do not extend beyond one glacial-interglacial cycle, hindering circumpolar comparison of past sea surface temperature (SST) evolution in the Southern Ocean. Here we present three alkenone-based Pleistocene SST records from the subantarctic and subtropical Pacific. We use a regional core top calibration data set to constrain the choice of calibrations for paleo SST estimation. Our core top data confirm that the alkenone-based U-37(K) and U-37(K') values correlate linearly with the SST, in a similar fashion as the most commonly used laboratory culture-based calibrations even at low temperatures (down to similar... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37610/36990.pdf |
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| Korff, Lucia; Von Dobeneck, Tilo; Frederichs, Thomas; Kasten, Sabine; Kuhn, Gerhard; Gersonde, Rainer; Diekmann, Bernhard. |
| The carbonate-free abyss of the North Pacific defies most paleoceanographic proxy methods and hence remains a blank spot in ocean and climate history. Paleomagnetic and rock magnetic, geochemical, and sedimentological methods were combined to date and analyze seven middle to late Pleistocene northwest Pacific sediment cores from water depths of 5100 to 5700m. Besides largely coherent tephra layers, the most striking features of these records are nearly magnetite-free zones corresponding to glacial marine isotope stages (MISs) 22, 12, 10, 8, 6, and 2. Magnetite depletion is correlated with organic carbon and quartz content and anticorrelated with biogenic barite and opal content. Within interglacial sections and mid-Pleistocene transition glacial stages MIS... |
| Tipo: Text |
Palavras-chave: Northwest Pacific Ocean; Carbon trapping; Magnetite dissolution; Mid-Pleistocene transition; Tephra layers; Abyssal sediments. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53247/54725.pdf |
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