Nd isotope composition of the terrigenous component of sediments as a tracer for the Heinrich events: a study in the NW Iberian continental margin

• Autor(a) principal: Martins, V.
• Data de Publicação: 2011
• Outros Autores: Santos, J. F., Ribeiro, S., Soares, A. S., Castro, N., Mackensen, A., Moreno, J., Rey, D., Rubio, B., Dias, J. M. A., Rocha, F.
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/9051
• topic: Galician continental slope; Last glaciation; Heinrich events; Nd isotope ratios; Sediment sources; Talude continental da Galiza; Última glaciação; Eventos de Heinrich; Razões isotópicas de Nd; Fontes dos sedimentos

The OMEX core KC 024-19 was studied aiming at to assess the influence of climate changes on the origin and transport of the sediments of the Galician continental slope, in the last 40 ka. The results show that sea level variation played a major role in the supply of the terrigenous sediments coming from the nearby continental areas, whose basement has a Variscan age. Additionally, coarse-grained clastic materials, corresponding to ice-rafted debris (IRD), were deposited through melting of icebergs during the Heinrich events (HE), in the last glaciation. The last four HE were identified in the core. The measured Nd isotope ratios reveal that there was a strong contribution of continental crustal sources significantly older than the Variscan basement for HE 1, 2 and 4. The most likely provenance of the coarse clasts deposited during these three events lie in NE America or Greenland, and the carrier icebergs should be fragments of the Laurentide Ice Sheet. In contrast, the HE 3 layer displays εNd values in the range of the compositions of the most common sediments in the core and, therefore, its IRD should have European source(s), which supports previous results obtained in other places of the European Atlantic margin.