MORFOMETRIA E PALEOECOLOGIA DE COCCOLITHUS PELAGICUS COCCOLITHAPHYCEAE, NANOPLÂNCTON CALCÁRIO, NA REGIÃO ATLÂNTICA, DURANTE O QUATERNÁRIO

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Coccolithus pelagicus subsp. pelagicus versus Coccolithus pelagicus subsp. braarudii (Coccolithophore, Haptophyta): A proxy for surface subarctic Atlantic waters off Iberia during the last 200 kyr

Publication . Narciso, Áurea; Cachão, Mario; Abreu, Lúcia de

A Multivariate Morphon Analysis (MMA) of Coccolithus pelagicus (s. l.) coccoliths was performed on 178 samples from an oceanic core recovered off the Portuguese margin (MD95-2040), in order to define the morphometric boundaries of its morphotypes and their behaviour during the last two glacial cycles. The recurrent occurrence of the smaller morphotype of this taxon, C. pelagicus subsp. pelagicus, was recognized for the first time off the Portuguese coast. Three sections, around Heinrich Layers 1 and 6 and Termination II-Eemian, were selected to establish high resolution comparisons between C. pelagicus subsp. pelagicus and C. pelagicus subsp. braarudii and two independent proxies for cold water masses: the records of the planktonic foraminifera Neogloboquadrina pachyderma (sinistral) and ice-rafted detritus (IRD). There is an overall negative correlation between C. pelagicus subsp. pelagicus and C. pelagicus subsp. braarudii as expressed by MMA Factor 1, the scores of which respond similarly to those of two non-cocolithophore proxies and consequently, is proposed as a calcareous nannoplankton proxy for the influence of subpolar waters in the region. Detailed analysis, however, showed occasional decoupling amongst these three proxies, which are used to highlight significant changes between the cooling–warming sequences of distinct events off Iberia.

2006Artigo científico

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Fundação para a Ciência e a Tecnologia

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SFRH/BD/8944/2002