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Were Ocean Impacts an Important Mechanism to Deliver Meteoritic Organic Matter to the Early Earth? Some Inferences from EltaninSeveral workers have addressed the potential for extraterrestrial delivery of volatles, including water and complex organic compounds, to the early Earth. For example, Chyba and Sagan (1992) argued that since impacts would destroy organic matter, most extraterrestrial organics must be delivered in the fine-fractions of interplanetary dust. More recent computer simulations (Pierazzo and Chyba, 1999), however, have shown that substantial amounts of amino acids may survive the impacts of large (km-sized) comets and that this may exceed the amounts derived from IDPs or Miller-Urey synthesis in the atmosphere. Once an ocean developed on the early Earth, impacts of small ,asteroids and comets into deep-ocean basins were potentially common and may have been the most likely events to deliver large amounts of organics. The deposits of the late Pliocene impact of the Eltanin asteroid into the Bellingshausen Sea provide the only record of a deep-ocean (approx. 5 km) impact that can be used to constrain models of these events. This impact was first discovered in 1981 as an Ir anomaly in sediment cores collected by the USNS Eltanin in 1965 (Kyte et al., 1981). In 1995, Polarstem expedition ANT XII/4 made the first geological survey of the suspected impact region. Three sediment cores sampled around the San Martin seamounts (approx. 57.5S, 91 W) contained well-preserved impact deposits that include disturbed ocean sediments and meteoritic impact ejecta (Gersonde et al., 1997). The latter is composed of shock- melted asteroidal materials and unmelted meteorites. In 2001, the FS Polarstem returned to the impact area during expedition ANT XVIII/5a. At least 16 cores were recovered that contain ejecta deposits. These cores and geophysical data from the expedition can be used to map the effects of the impact over a large region of the ocean floor.
Document ID
20030063259
Document Type
Reprint (Version printed in journal)
Authors
Kyte, Frank T.
(California Univ. Los Angeles, CA, United States)
Gersonde, Rainer
(Alfred-Wegener-Inst. for Polar and Marine Research Bremerhaven, Germany)
Kuhn. Gerhard
(Alfred-Wegener-Inst. for Polar and Marine Research Bremerhaven, Germany)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Astrobiology
Volume: 4
Issue: 563 Abs 12622
Subject Category
Space Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG5-9441
Distribution Limits
Public
Copyright
Other
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