Holocene neoglacial events in the Bransfield Strait (Antarctica). Palaeocenographic and paleoclimatic significance
[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 s...
| Autores: | , , , , , , |
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| Tipo de documento: | artigo |
| Data de publicação: | 2006 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositório: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/2360 |
| Acesso em linha: | http://hdl.handle.net/10261/2360 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Diatoms Geochemistry Neoglacial events Palaeoceanography Palaeoclimatology Holocene Bransfield Strait Antarctica Diatomeas Geoquímica Paleoceanografía Paleoclimatología Holoceno Estrecho de Bransfield Antártida Eventos neoglaciales |
| Resumo: | [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. |
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