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  Revised age of the Eltanin Impact in Southern Ocean

Frederichs, T.
Bleil, U.
Gersonde, R.
Kuhn, G.
American Geophysical Union, Fall Meeting 2002, abstract #OS22C-0286

    The late Pliocene Eltanin impact at around 57.5° S / 90.5° W in the
    Southern Ocean has formerly been dated to about 2.15 Ma. This
    estimate was based on regional analyses of the geological record
    combining bathymetric and seismic surveys with detailed
    sedimentologic, geochemical (e.g., chromium and iridium anaomalies),
    biostratigraphic (diatoms and calcareous nanofossils) and
    principally on magnetostratigraphic studies of sedimentary deposits
    recovered in 3 piston cores. Only one of them apparently contained
    an adequately complete and continuous late Pliocene sequence,
    however, whereas a hiatus spanning major parts of the Matuyama Chron
    was encountered in the other two cores. The age assignment therefore
    essentially relied on the identification of the magnetostratigraphic
    Réunion Event (C2r.1n) and the Thalassiosira kolbei - Fragilariopsis
    matuyamae diatom zone directly above the impact related deposits in
    a single core. 

    New chronostratigraphic data presented here were
    obtained on a series of 4 piston cores retrieved during the 2001 R/V
    Polarstern cruise ANT-XVIII/5a in the wider vicinity of the Eltanin
    impact area. Initial correlation of their magnetic susceptibility
    records with previous data sets substantiated the age estimate of
    the impact event in the early Matuyama Chron. High-resolution
    paleomagnetic analyses provided convincing evidence, at least in two
    cores with high enough sedimentation rates in the critical interval,
    that the Eltanin impact not only predates the geomagnetic Réunion
    Event, but also the unnamed normal polarity event (C2r.2r-1) listed
    in the most recent Geomagnetic Polarity Time Scale. This finding
    would now constrain the Eltanin impact age to 2511+/-70 ka, between
    the top of the Gauss Chron (2581 ka) and the base of the C2r.2r-1
    event (2441 ka), a climate period that has been affected by major
    glaciations on the Northern hemisphere. 

Keywords: 1630 Impact phenomena, 4564 Tsunamis and storm surges, 5420
Impact phenomena (includes cratering)
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