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Registros recuperados: 8
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Cocolitóforos en sedimentos marinos frente a la entrada occidental del Estrecho de Magallanes (53°S) revelan cambios en la productividad durante los últimos 30.000 años ArchiMer
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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Deglacial-Holocene environmental changes at the Pacific entrance of the Strait of Magellan ArchiMer
Harada, Naomi; Ninnemann, Ulysses; Lange, Carina B.; Marchant, Margarita E.; Sato, Miyako; Ahagon, Naokazu; Pantoja, Silvio.
We show environmental and nitrogen cycle changes between 13 and 2.5 kyr BP (from the latest deglaciation to the Holocene) based on biogeochemical records in a sediment core from the Pacific entrance of the Strait of Magellan. Organic carbon, total nitrogen, and C-37 alkenone contents were low during 13-9 kyr BP but increased rapidly at 8 kyr BP. The relative contribution of tetra-unsaturated C-37 alkenone, used as a salinity proxy, suggests low salinity during 13-9 kyr BP changing to high salinity at 8 kyr BP. Planktic foraminifer data showed that Globigerina bulloides was more abundant during the deglacial-early Holocene than in the mid-late Holocene, whereas abundances of Neogloboquadrina pachyderma showed the opposite pattern. This evidence plus...
Tipo: Text Palavras-chave: Biogenic components; Delta C-13; Delta N-15; Planktic foraminifera; Alkenone; Sea surface temperature; Southern Patagonia.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00264/37548/36825.pdf
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Environmental and coastline changes controlling Holocene carbon accumulation rates in fjords of the western Strait of Magellan region ArchiMer
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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Glacial reduction and millennial-scale variations in Drake Passage throughflow ArchiMer
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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Holocene sea-surface temperature variability in the Chilean fjord region ArchiMer
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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Holocene variations in productivity associated with changes in glacier activity and freshwater flux in the central basin of the Strait of Magellan ArchiMer
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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Latitudinal patterns of export production recorded in surface sediments of the Chilean Patagonian fjords (41-55 degrees S) as a response to water column productivity ArchiMer
Aracena, Claudia; Lange, Carina B.; Iriarte, Jose Luis; Rebolledo, Lorena; Pantoja, Silvio.
The Chilean Patagonian fjords region (41-56 degrees S) is characterized by highly complex geomorphology and hydrographic conditions, and strong seasonal and latitudinal patterns in precipitation, freshwater discharge, glacier coverage, and light regime; all of these directly affect biological production in the water column. In this study, we compiled published and new information on water column properties (primary production, nutrients) and surface sediment characteristics (biogenic opal, organic carbon, molar C/N, bulk sedimentary delta(13)C(org)) from the Chilean Patagonian fjords between 41 degrees S and 55 degrees S, describing herein the latitudinal pattern of water column productivity and its imprint in the underlying sediments. Based on information...
Tipo: Text Palavras-chave: Biogenic opal; Organic carbon; Stable carbon isotopes; Primary production; Fjords; Patagonia.
Ano: 2011 URL: https://archimer.ifremer.fr/doc/00214/32519/30998.pdf
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Siliceous productivity changes in Gulf of Ancud sediments (42 degrees S, 72 degrees W), southern Chile, over the last similar to 150 years ArchiMer
Rebolledo, Lorena; Gonzalez, Humberto E.; Munoz, Praxedes; Iriarte, Jose L.; Lange, Carina B.; Pantoja, Silvio; Salamanca, Marco.
We evaluated changes in siliceous export production and the source of organic matter preserved in sediment core MD07-3109H recovered from the Gulf of Ancud, Chiloe Inner Sea (42 degrees S, 72 degrees W, water column depth: 328 m), southern Chile. We analyzed the abundance of siliceous microfossils (diatoms, silicoflagellates, sponge spicules, Chrysophyte cysts, phytoliths), geochemical proxies (weight percent silicon %Si(OPAL), organic carbon, total nitrogen. C/N molar), and sediment stable isotopes (delta(13)C(org), delta(15)N). Chronology based on (210)Pb and (14)C provided an accumulated age of 144 years at the base of the core. Sediments of core MD07-3109H are predominantly marine in origin, averaging delta(13)C(org)=-20.75 parts per thousand+0.82,...
Tipo: Text Palavras-chave: Productivity; Siliceous microfossil; Geochemical proxies; Sediments; Gulf of Ancud; Chile.
Ano: 2011 URL: https://archimer.ifremer.fr/doc/00214/32520/30999.pdf
Registros recuperados: 8
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