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Calcareous Nannofossil Evidence for Marine Isotopic Stage 31 (1 Ma) in ANDRILL MIS Core (Western Ross Sea, Antarctica)

Villa, G ; Persico, D ; Wise, S W

Eos (Washington, D.C.), 2007-12, Vol.88 (52)

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  • Título:
    Calcareous Nannofossil Evidence for Marine Isotopic Stage 31 (1 Ma) in ANDRILL MIS Core (Western Ross Sea, Antarctica)
  • Autor: Villa, G ; Persico, D ; Wise, S W
  • É parte de: Eos (Washington, D.C.), 2007-12, Vol.88 (52)
  • Notas: SourceType-Scholarly Journals-2
    ObjectType-Feature-2
    ObjectType-Conference Paper-1
    content type line 23
    SourceType-Conference Papers & Proceedings-1
    ObjectType-Article-3
  • Descrição: Quaternary sediments south of the Antarctic Divergence (AD) at about 63-65 deg S were long considered to be barren of calcareous nannofossils until their discovery there within the past decade. The study of such fossils in Quaternary sediments of periantarctic basins and their fluctuations and relationships with glacial-interglacial cycles, therefore, is of fundamental importance in reconstructing palaeoclimatic conditions for this time interval. To further verify the presence of calcareous nannofossils within Antarctic Quaternary and older Neogene sediments, we have undertaken a micropalaeontological study of the recently cored ANDRILL McMurdo Ice Shelf (MIS) sediments. During drilling, calcareous nannofossils in the form of calcareous dinoflagellates were detected in 31 samples of some 530 examined. These occurred along with calcareous spicules (calciospongia) and occasional fragments of ostracods and foraminifers within several biogenic carbonate intervals at about 27, 31, and 91-98 mbsf, but only in scattered samples between 98 and 426 and 554 to 556 mbsf. Subsequent shore-based analysis of 15 toothpick samples from 93-95 mbsf revealed for the first time the presence of Pleistocene coccolithophorids at these high southern latitudes (77 deg S), including Coccolithus pelagicus, Coccolithus crassipons, Pseudoemiliania lacunosa, and Reticulofenestra sp. in sediments of Marine Isotopic Stage 31. As the lower temperature limit for living calcareous nannoplankton is 2.5 deg C, the presence of these nannofossils, though rare, is an indication of ice-free sea surface temperatures warmer than today in the Ross Sea at 1 Ma.
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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