SciELO - Scientific Electronic Library Online

 
vol.47 número4Los plesiosaurios (Reptilia, Sauropterygia) más antiguos del Cretácico Superior bajo de la Patagonia austral, Argentina índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Artigo

Indicadores

  • Não possue artigos citadosCitado por SciELO

Links relacionados

  • Em processo de indexaçãoCitado por Google
  • Não possue artigos similaresSimilares em SciELO
  • Em processo de indexaçãoSimilares em Google

Bookmark


Ameghiniana

versão impressa ISSN 0002-7014

Resumo

GUERSTEIN, G. Raquel  e  DANERS, Gloria. Paleogene distribution of Enneadocysta (Dinoflagellata) in the Southwestern Atlantic Ocean: paleoceanographic implications. Ameghiniana [online]. 2010, vol.47, n.4, pp. 461-478. ISSN 0002-7014.

The study of Middle to Late Eocene dinoflagellate cyst assemblages from subtropical Southwest Atlantic basins shows the presence of species of Enneadocysta, including E. dictyostila (Menéndez) Stover and Williams emend. Fensome et al., E. brevistila Fensome et al. and E. multicornuta (Eaton) Stover and Williams. The species Enneadocysta dictyostila has been widely recorded in middle Paleogene sections from Southern Hemisphere high latitudes. High representativity of Enneadocysta spp., along with other components of the Southern Ocean endemic dinoflagellate flora, have been observed in samples from Colorado Basin (~38°S), Argentina and Punta del Este Basin (~36°S), Uruguay. Previous research in the Tasman area has related the presence of these endemic taxa at mid-lat-itudes to the formation of a strong clockwise subpolar gyre ("cold trap") favoured by the continental blockage of the Tasman Gateway. In this paper we propose that the observed dinoflagellate cyst distribution in the Southwest Atlantic basins can be explained by a similar dynamical mechanism operating close to the present Weddell Gyre. The blockage of the Tasman Gateway and a partially open Drake Passage both contributed to the formation of a strong western-intensified clockwise gyre that may have transported the endemic flora components, mainly represented by Enneadocysta spp., from the Antarctic continent northward along the Southwest Atlantic Shelf during the Middle - Late Eocene.

Palavras-chave : Dinoflagellate cysts; Circum-Antarctic endemic flora; Eocene; Southwest Atlantic Ocean; Oceanic paleocirculation.

        · resumo em Espanhol     · texto em Espanhol     · pdf em Espanhol