Evidence for Impact Generated Mass Extinctions

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Evidence for Impact Generated Mass Extinctions
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The Cratering Record
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The Moon
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Impact Craters on the Earth
From Grieve 1993
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Barringer Meteor Crater, Arizona
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Impact History of the Earth and Moon
Sleep et al., Nature 342 139 (1989)
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Impact Event at the 65 myr old Cretaceous/Tertiary
Boundary
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Some Consequences of the KT Impact

• Severe ground shaking, Tsunami
• Injection of dust into stratosphere, global
  darkness global fires
• Atmospheric injection of CO2 from carbonate
  target, global warming

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65 myr old Cretaceous-Tertiary Boundary
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Iceland
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Some Consequences of Volcanism

• Release of toxic pollutants, sulfur, CO2,
  fluorine, chlorine
• Environmental degradation of ecosystems and
  habitats (e.g. acid rain, ocean anoxia)
• Atmospheric injection of volcanic CO2 from
  eruptions, global warming

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Shocked Quartz, Microspherules, Tektites
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Soot from the 65 myr old K/T Boundary Clay
Stevns Klint, Denmark
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Buckminsterfullerene
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Kroto et al., Nature 318, p. 162 (1985)
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Fullerene Bucky Generator
Kratschmer et al., Nature 347, p. 354 (1990)
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Extraction Protocol for Fullerene Carbon
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Noble Gas Incorporation in Graphitic Smokes
E. K. Olsen, T. D. Swindle, J. A. Nuth, F.
Ferguson, LPSC XXXI, 2000
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Sublimation of Fullerenes
Toluene extracted fullerene from Swindle residue.
Fullerene can also be sublimed directly from the
soot
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Window Mechanism for the encapsulation of atoms
inside the fullerene cage.
A.
B.
(A) C60 or buckminsterfullerene.
(B) C60 with an atom inside.
D.
C.
(C) C60 with an atom inside and with a bond
broken (open window). (D) Same molecule as (C)
but with the atom moving out through the window.
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Fullerenes at the 65 myr old KT Boundary
Don Davis

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Soot from the 65 myr old K/T Boundary Clay
Heymann et al., Science 256, 545 (1994)
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The Origin if Fullerenes at the KT Boundary
Possible scenarios for fullerenes in the KT
impact deposits are (1) the fullerenes were
formed on impact (2) the fullerenes were already
present and survived the impact or (3)
Fullerenes in the KT sediments were formed as a
result of global wildfires triggered by the
impact event (Heymann et al., Science 1994)
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KT Fullerene Results
Fullerenes isolated from several KTB sites
worldwide contained trapped helium that was
similar to some meteorites and interplanetary
dust particles
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The Great Dying
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Fullerene Results from the PTB
The helium concentrations for both the Meishan,
China and Sasayama, Japan PTB sediments are
similar to the planetary component in
meteorites (1.4 x 10-4)
Measured 3He/36Ar also resembles the planetary
ratio (as opposed to a solar gas reservoir)
The 40Ar/36Ar ratios are a mixture of air and
planetary (75 to 25) with an atmospheric
38Ar/36Ar ratio, also consistent with a
carbonaceous chondrite (e.g. Murchison)
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Noble Gas Results for PTB
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Impact Tracers
Carbon Isotopes
Microspherules
Carbon Soot
Iridium
Fullerenes
Shattercones
Shocked Quartz
Chixculub Crater
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The Permian-Triassic Boundary in Antarctica
Coal Sac Bluff, Queen Alexandra Range
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Fullerenes w/trapped Noble Gases at Graphite
Peak, Antarctica
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Impact Site for the PTB?
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