Holocene neoglacial events in the Bransfield Strait (Antarctica). Palaeocenographic and paleoclimatic significance

• Published in: Scientia Marina
• Main Authors: Bárcena, María Ángeles, Fabrés, Joan, Isla, Enrique, Flores, José Abel, Sierro, Francisco Javier, Canals, Miquel, Palanques, Albert
• Format: Article in Journal/Newspaper
• Language: English
• Published: Consejo Superior de Investigaciones Científicas (España) 2006
• Subjects: Diatoms; Geochemistry; Neoglacial events; Palaeoceanography; Palaeoclimatology; Holocene; Bransfield Strait; Antarctica; Diatomeas; Geoquímica; Paleoceanografía; Paleoclimatología; Holoceno; Estrecho de Bransfield; Antártida; Eventos neoglaciales; Estrecho; Hielo; Weddell; Antarc*; ice core; Sea ice
• Online Access: http://hdl.handle.net/10261/2360; https://doi.org/10.3989/scimar.2006.70n4607

[EN] Geochemical analysis, micropalaeontological analysis and radiometric dating techniques were performed on four gravity cores, G-1, G-2, A-3 and A-6, recovered during the BIO Hesperides expeditions GEBRA-93 and FRUELA-96 from the Bransfield Strait (Antarctica). Moreover, in order to improve the sedimentation rate control we tentatively relate abundance variations in the sea-ice taxa group (SITG) to air temperature estimations based on Deuterium contents in Vostok ice-core. The results of diatom analyses were related to the sequence of neoglacial events that have occurred over the last three millennia. For these periods, a restricted communication between the Weddell, Bransfield and Bellingshausen seas has been proposed. The abundance patterns of diatom valves, resting spores (RS) of the diatom Chaetoceros and opal content agree with the high productivity values previously reported for the area. The significant reduction Chaetoceros RS towards the present is interpreted as a reduction in surface productivity. Trend differences between Chaetoceros RS and TOC contents are explained in terms of organic matter preservation. Diatom communities from the Bransfield Strait did not play an important role in the global CO2 cycle during cold periods. Bio- and geochemical changes have overprinted high frequency cyclicity at about 200-300 yr, which might be related to the 200-yr solar cycle. [ES] Se han realizado análisis geoquímicos y micropaleontológicos, así como técnicas de datación radiométricas sobre cuatro testigos de gravedad (G-1, G2, A-3 y A-6) recuperados durante las campañas del BIO Hespérides Gebra-93 y Fruela-96 en el Estrecho de Bransfield (Antártida). Se han correlacionado las estimaciones de temperatura del aire, derivadas del contenido en Deuterio en el testigo de hielo Vostok, con la abundancia del grupo de taxones de mar helado (SITG). Los resultados obtenidos del análisis de diatomeas han sido relacionados con la secuencia de eventos neoglaciales que tuvieron lugar durante los últimos 3000 años. Se ...