DATING AN ABYSSAL OCEAN IMPACT CRATER

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DATING AN ABYSSAL OCEAN IMPACT CRATER

• Karol Petreshock
• 11/10/03
• Research Mentor Dallas Abbott, LDEO
• Seminar Advisor Martin Stute , Environmental
  Science, Barnard College

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INTRODUCTION

• Impact craters influence geological and
  biological evolution
• 165 Impact craters on Earth (Gersonde 2002)
• The Ewing Structure and Eltanin Structure are
  the only discovered deep ocean impact craters
• Oceanic basins cover 60 of the Earths Surface
  (Gersonde 2002)
• Its estimated that there should be 35 or more
  deep ocean impact craters present on Earth
  (Reynolds 2001)

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REMODELING THE EVENT

• Eltanin Asteroid hits Earth in The Late
  Pliocene-Tsunami Theory
• Possibly 200-300m high hitting Southern tip of
  South America (Asphaug 2002)
• Disturbed sediments over several Km
• Ejecta Blanket
• Vapor Explosion Meteoritic/ Sedimentary Debris
  into high atmosphere (Gersonde 2001)

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THE ELTANIN IMPACT CRATER

• Location Bellinghausen sea , Centered at 537S,
  901W
• Diameter 130 Km (Glatz et all 2002)
• First discovered as Iridium anomaly 1981(Kyte et
  al 1981)
• Seismic and Bathymetric Data
• Unmelted meteoritic fragments and vesicular
  impact melt (Kyte 2002)
• Ni-Rich Spherules like that of K/T Boundary
  ejecta(Gersonde 1995)
• Late Pliocene 2.15 mya. 2.4 mya by
  biostratigraphy (Gersonde 1995)
• Really an Impact Event?

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THESIS

• Using Biostatigraphy and Magnetostratigraphy,
  provide a date for the Eltanin (primary Focus)
  and the Ewing Impact Craters.
• Associate these events with mass extinctions
  and/or climate change

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APPROACH

• 4 Eltanin Cores RC12-228, RC12-230, RC17-211, RC
  18-33
• Samples for taken for magnetostratigraphy and
  sieving at 2 cm intervals.
• Barington Magnetic Susceptibility Meter
• Sieves 150, 63, 38 microns
• SEM Analysis Photos and Chemical Composition
  provided by Dee Breger, LDEO

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PROVIDING GEOLOCAL DATES

• Magnetostratigraphy magnetic polarity reversals
  on Earth well dated
• Biostratigraphy-Microfossils
• Potassium-Argon Dating-radioactive isotope K-40
  and Ar-40

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PRELIMINARY RESULTS
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PRELIMINARY RESULTS
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PRELIMINARY RESULTS
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PRELIMINARY RESULTS

• K-feldspar microcrystite from Ewing ODP core
  1217A 56-58 cm in depth
• No spherules yet in Eltanin cores
• Possible meteoric fragments

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IMPLICATIONS

• Discovery of impact structures on the ocean
  floor rare discovery
• Evolution of atmosphere and life-K/T Boundary
  65mya (Gersonde 2001)
• Pliocene Extinctions 2.0-2.6 mya and Early Humans
  
• Atmospheric fallout and global climate change?
• Ewing Impact related to Miocene extinctions?

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REFERENCES
Asphaug, E., and Ward, S.N., , (2002) Impact
Tsunami-Eltanin Deep Sea research II 49
1073-1089 Gersonde, R, Kyte, F.T.,B. Diekmann,
J Flores . Bliel, U. G. Kuhn, A. Abelmann, D.
Volker F.J. Sierro and J.A. Bostswick .(1997)
Geological record and reconstuction of th eLAte
Pliocene Impact On The Eltanin Asteroid in the
Southern Ocean Nature 357-365 Gersonde, R,.
Duetch, Alexnader Duetch, Boris Ivanoc, Kyte,
Frank (2002) Oceanic Impacts- A growing Field on
Fundamental Geoscience Deep Sea REesearch II
(49) 951-957 Gersonde, R, Kyte, F.T., Abelmann,
A. Bliel, U. G. Kuhn and F.J. Sierro.(2001)A
Late Pleistocene Asteroid Impact into the Deep
Ocean- it Documentation and Paleoenvironmantal
Application Glatz, C.A. Dallas, A. (2002)
Senior Thesis A possible Abyssal Ocean Impact
Crater University of Maine Kyte, . Frank (2002)
Composition of melt Debris From the Eltanin
impact Strewn field, Bellinghausen Sea Deep Sea
research II 49 p1029-1047
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ACKNOWLEDGEMENTS

• Dallas Abbott
• Martin Stute
• Dee Breger
• Lloyd Burkle