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| Registros recuperados: 12 | |
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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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| Siani, Giuseppe; Michel, Elisabeth; De Pol-holz, Ricardo; Devries, Tim; Lamy, Frank; Carel, Melanie; Isguder, Gulay; Dewilde, Fabien; Lourantou, Anna. |
| The Southern Ocean plays a prominent role in the Earth's climate and carbon cycle. Changes in the Southern Ocean circulation may have regulated the release of CO2 to the atmosphere from a deep-ocean reservoir during the last deglaciation. However, the path and exact timing of this deglacial CO2 release are still under debate. Here we present measurements of deglacial surface reservoir C-14 age changes in the eastern Pacific sector of the Southern Ocean, obtained by C-14 dating of tephra deposited over the marine and terrestrial regions. These results, along with records of foraminifera benthic-planktic C-14 age and delta C-13 difference, provide evidence for three periods of enhanced upwelling in the Southern Ocean during the last deglaciation, supporting... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00263/37472/36804.pdf |
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| Caniupan, Magaly; Lamy, Frank; Lange, Carina B.; Kaiser, Jerome; Kilian, Rolf; Arz, Helge W.; Leon, Tania; Mollenhauer, Gesine; Sandoval, Susana; De Pol-holz, Ricardo; Pantoja, Silvio; Wellner, Julia; Tiedemann, Ralf. |
| Here we provide three new Holocene (11-0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50-53 degrees S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past similar to 0.6 cal ka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During... |
| Tipo: Text |
Palavras-chave: Holocene; Alkenones; Sea-surface temperature; Fjords; Chile. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40088/39292.pdf |
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| Arz, Helge W.; Lamy, Frank; Ganopolski, Andrey; Nowaczyk, Norbert; Paetzold, Juergen. |
| Based on a radiocarbon and paleomagnetically dated sediment record from the northern Red Sea and the exceptional sensitivity of the regional changes in the oxygen isotope composition of sea water to the sea-level-dependent water exchange with the Indian Ocean, we provide a new global sea-level reconstruction spanning the last glacial period. The sea-level record has been extracted from the temperature-corrected benthic stable oxygen isotopes using coral-based sea-level data as constraints for the sea-level/oxygen isotope relationship. Although, the general features of this millennial-scale sea-level records have strong similarities to the rather symmetric and gradual Southern Hemisphere climate patterns, we observe, in constrast to previous findings,... |
| Tipo: Text |
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| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00236/34700/33072.pdf |
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| Sanchez, Gloria E.; Lange, Carina B.; Flores, Jose-abel; Caniupan, Magaly; Lamy, Frank. |
| We present a new record of coccolithophore (coccoliths) export productivity for the past 30,000 years based on the study of a marine sediment core collected at the western entrance of the Strait of Magellan (Core MD07-3128; 53 degrees S, 75 degrees W). This sediment core revealed the presence of an assemblage composed by thirteen coccolithophore taxa, dominated by small Gephyrocapsa (> 80% of the total assemblage on the average) and accompanied, in less proportions (1-10%), by two morphotypes of Emiliana huxleyi, Coccolithus pelagicus and Calcidiscus leptoporus. Coccolith concentration and CaCO3 content were strongly correlated (P << 0.01; R-2 = 0.63). In general, both records were in phase with alkenone-derived sea-surface temperature (Caniupan... |
| Tipo: Text |
Palavras-chave: Coccolithophores; Last Glacial Maximum; Holocene; Southern Chile. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00289/40052/38797.pdf |
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| Aracena, Claudia; Kilian, Rolf; Lange, Carina B.; Bertrand, Sebastien; Lamy, Frank; Arz, Helge W.; De Pol-holz, Ricardo; Baeza, Oscar; Pantoja, Silvio; Kissel, Catherine. |
| One of the most important factors controlling fjord primary production in southernmost Patagonia is the variability in the thermohaline structure of the water column. In the present-day environment, thermal stratification is mostly related to freshwater input and in particular, the seasonal melting of glaciers. Here we assess whether this relation between fjord productivity and freshwater input holds true for the Holocene, using a sediment record from the central basin of the Strait of Magellan (core MD07-3132, 53°44.17′S; 70°19.03′W, 301 m). Our approach relies on a proxy-based reconstruction of fjord sea surface temperature (alkenone SST), paleosalinity, freshwater input, and paleoproductivity. The results indicate that, during the early Holocene, the... |
| Tipo: Text |
Palavras-chave: Strait of Magellan; Holocene; Paleoproductivity; Thermohaline conditions. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00294/40518/39325.pdf |
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| Bahr, Andre; Lamy, Frank; Arz, Helge W.; Major, Candace; Kwiecien, Olga; Wefer, Gerold. |
| [1] New Mg/Ca, Sr/Ca, and published stable oxygen isotope and Sr-87/(86) Sr data obtained on ostracods from gravity cores located on the northwestern Black Sea slope were used to infer changes in the Black Sea hydrology and water chemistry for the period between 30 to 8 ka B. P. ( calibrated radiocarbon years). The period prior to 16.5 ka B. P. was characterized by stable conditions in all records until a distinct drop in delta O-18 values combined with a sharp increase in Sr-87/(86) Sr occurred between 16.5 and 14.8 ka B. P. This event is attributed to an increased runoff from the northern drainage area of the Black Sea between Heinrich Event 1 and the onset of the Bolling warm period. While the Mg/Ca and Sr/Ca records remained rather unaffected by this... |
| Tipo: Text |
Palavras-chave: Black Sea; Ostracods; Trace elements. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00209/31989/30432.pdf |
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| Lamy, Frank; Arz, Helge W.; Kilianc, Rolf; Lange, Carina B.; Lembke-jene, Lester; Wengler, Marc; Kaiser, Jerome; Baeza-urrea, Oscar; Hall, Ian R.; Harada, Naomi; Tiedemann, Ralf. |
| The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through this gateway is, therefore, crucial for advancing our understanding of the Southern Ocean's role in global ocean and climate variability. Here, we reconstruct changes in DP throughflow dynamics over the past 65,000 y based on grain size and geochemical properties of sediment records from the southernmost continental margin of South America. Combined with published sediment records from the Scotia Sea, we argue for a considerable total... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Drake Passage; Antarctic Circumpolar Current; Glacial-interglacial changes; Sedimentology. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46233/46119.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... |
| Tipo: Text |
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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... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37610/36990.pdf |
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| Ríos, Francisco; Kilian, Rolf; Lange, Carina B.; Baeza-urrea, Oscar; Arz, Helge W.; Zindorf, Mark; De Pol-holz, Ricardo; Lamy, Frank. |
| Organic-rich sediments of the southernmost Chilean Pacific coast and its fjord system constitute an important component of the global marine carbon budget. Sediment records from Trampa and Caribe bays and Churruca fjord in the western Magellan fjord system have been analyzed with the goal of understanding the factors controlling carbon accumulation and its regional fluctuation throughout the Holocene. The individual response in paleoproductivity at the different sites and related variations in accumulation rates document a very complex interplay among local and regional-scale environmental changes, and coastline elevation across the Holocene. Shallow sill basins close to the Pacific coast, as the ones studied here, are particularly sensitive to these... |
| Tipo: Text |
Palavras-chave: Patagonian fjord sediments; Paleoproductivity; Carbon accumulation; Biogenic carbonate; Marine transgression; Holocene. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72576/71536.pdf |
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| Registros recuperados: 12 | |
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