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Evidence for Impact Generated Mass Extinctions.

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Presentation on theme: "Evidence for Impact Generated Mass Extinctions."— Presentation transcript:

1 Evidence for Impact Generated Mass Extinctions

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3 The Cratering Record

4 The Moon

5 Impact Craters on the Earth From Grieve 1993

6 Barringer “Meteor” Crater, Arizona

7 Impact History of the Earth and Moon Sleep et al., Nature 342 139 (1989)

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9 Impact Event at the 65 myr old Cretaceous/Tertiary Boundary

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12 Some Consequences of the KT Impact Severe ground shaking, Tsunami Injection of dust into stratosphere, global darkness global fires Atmospheric injection of CO 2 from carbonate target, global warming

13 65 myr old Cretaceous-Tertiary Boundary

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15 Iceland

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17 Some Consequences of Volcanism Release of toxic pollutants, sulfur, CO 2, fluorine, chlorine Environmental degradation of ecosystems and habitats (e.g. acid rain, ocean anoxia) Atmospheric injection of volcanic CO 2 from eruptions, global warming

18 Shocked Quartz, Microspherules, Tektites

19 Soot from the 65 myr old K/T Boundary Clay Stevns Klint, Denmark

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24 Buckminsterfullerene

25 Kroto et al., Nature 318, p. 162 (1985)

26 Kratschmer et al., Nature 347, p. 354 (1990) Fullerene ‘Bucky’ Generator

27 Extraction Protocol for Fullerene Carbon

28 Noble Gas Incorporation in Graphitic Smokes E. K. Olsen, T. D. Swindle, J. A. Nuth, F. Ferguson, LPSC XXXI, 2000

29 Sublimation of Fullerenes Toluene extracted fullerene from Swindle residue. Fullerene can also be sublimed directly from the soot

30 ‘Window Mechanism’ for the encapsulation of atoms inside the fullerene cage. A. B. (A) C 60 or buckminsterfullerene. (B) C 60 with an atom inside. (C) C 60 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. C. D.

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33 Don Davis Fullerenes at the 65 myr old KT Boundary

34 Soot from the 65 myr old K/T Boundary Clay Heymann et al., Science 256, 545 (1994)

35 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)

36 KT Fullerene Results Fullerenes isolated from several KTB sites worldwide contained trapped helium that was similar to some meteorites and interplanetary dust particles

37 The Great Dying

38 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 3 He/ 36 Ar also resembles the “planetary” ratio (as opposed to a solar gas reservoir) The 40 Ar/ 36 Ar ratios are a mixture of air and “planetary” (75% to 25%) with an atmospheric 38 Ar/ 36 Ar ratio, also consistent with a carbonaceous chondrite (e.g. Murchison)

39 Noble Gas Results for PTB

40 Impact Tracers Carbon Isotopes Carbon ‘Soot’ Iridium Chixculub Crater Shattercones Fullerenes Microspherules Shocked Quartz

41 The Permian-Triassic Boundary in Antarctica Coal Sac Bluff, Queen Alexandra Range

42 Fullerenes w/trapped Noble Gases at Graphite Peak, Antarctica

43 Impact Site for the PTB?

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