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Registros recuperados: 7
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Deglacial-Holocene environmental changes at the Pacific entrance of the Strait of Magellan 5
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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Geochemistry of surface sediments from the fjords of Northern Chilean Patagonia (44-47 degrees S): Spatial variability and implications for paleoclimate reconstructions 5
Bertrand, Sebastien; Hughen, Konrad A.; Sepulveda, Julio; Pantoja, Silvio.
The Patagonian fjords have a clear potential to provide high-resolution sedimentary and geochemical records of past climate and environmental change in the Southern Andes. To improve our ability to interpret these proxy records, we investigated the processes that control fjord sediment inorganic geochemistry through a geochemical, mineralogical and sedimentological analysis of surface sediment samples from the fjords of Northern Chilean Patagonia. A simple Terrestrial Index based on measurements of salinity and Fraction of Terrestrial Carbon was used to estimate the terrestrial input/river discharge at each site. Our results demonstrate that, under the cold climate conditions of Patagonia, chemical weathering is weak and the inorganic geochemical...
Tipo: Text
Ano: 2012 URL: https://archimer.ifremer.fr/doc/00092/20299/17933.pdf
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Holocene sea-surface temperature variability in the Chilean fjord region 5
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 5
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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Late Holocene covariability of the southern westerlies and sea surface temperature in northern Chilean Patagonia 5
Bertrand, Sebastien; Hughen, Konrad; Sepulveda, Julio; Pantoja, Silvio.
The climate of Chilean Patagonia is strongly influenced by the southern westerlies, which control the amount and latitudinal distribution of precipitation in the southern Andes. In austral summer, the Southern Westerly Wind Belt (SWWB) is restricted to the high latitudes. It expands northward in winter, which results in a strong precipitation seasonality between similar to 35 and 45 degrees S. Here, we present a new precipitation seasonality proxy record from Quitralco fjord (46 degrees S), where relatively small latitudinal shifts of the SWWB result in large changes in precipitation seasonality. Our 1400 yr record is based on sedimentological and geochemical data obtained on a sediment core collected in front of a small river that drains the Patagonian...
Tipo: Text Palavras-chave: Southern westerlies; Inorganic geochemistry; Paleohydrology; Paleohydroclimatology; Fjord sediments; Southern South America; Chilean Patagonia.
Ano: 2014 URL: https://archimer.ifremer.fr/doc/00289/40044/39295.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 5
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 5
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: 7
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