Evidence for Impact Generated Mass Extinctions

Evidence for Impact Generated Mass Extinctions

The Cratering Record

The Moon

Impact Craters on the Earth

From Grieve 1993

Barringer “Meteor” Crater, Arizona

Impact History of the Earth and Moon

Sleep et al., Nature 342 139 (1989)

Impact Event at the 65 myr old Cretaceous/Tertiary Boundary

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

65 myr old Cretaceous-Tertiary Boundary

Iceland

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

Shocked Quartz, Microspherules, Tektites

Soot from the 65 myr old K/T Boundary Clay

Stevns Klint, Denmark

Buckminsterfullerene

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

Kratschmer et al., Nature 347, p. 354 (1990)

Fullerene ‘Bucky’ Generator

Extraction Protocol for Fullerene Carbon

Noble Gas Incorporation in Graphitic Smokes

E. K. Olsen, T. D. Swindle, J. A. Nuth, F. Ferguson, LPSC XXXI, 2000

Sublimation of Fullerenes

Toluene extractedfullerene from Swindleresidue. Fullerene canalso be sublimed directlyfrom the soot

‘Window Mechanism’ for the encapsulation of atoms inside thefullerene cage.

A. B.

(A) C60 or buckminsterfullerene. (B) C60 with an atom inside.

(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 thewindow.

C. D.

Don Davis

Fullerenes at the 65 myr old KT Boundary

Soot from the 65 myr old K/T Boundary Clay

Heymann et al., Science 256, 545 (1994)

The Origin if Fullerenes at the KT Boundary

Possible scenarios for fullerenes in the KT impactdeposits are:

(1) the fullerenes were formed on impact

(2) the fullerenes were already present and survived theimpact 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)

KT Fullerene Results

Fullerenes isolated from several KTB sites worldwidecontained trapped helium that was similar tosome meteorites and interplanetary dust particles

The Great Dying

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, alsoconsistent with a carbonaceous chondrite (e.g. Murchison)

Noble Gas Results for PTB

Impact TracersCarbon Isotopes

Carbon ‘Soot’

Iridium

Chixculub Crater

Shattercones

Fullerenes

Microspherules

Shocked Quartz

The Permian-Triassic Boundary in Antarctica

Coal Sac Bluff, Queen Alexandra Range

Fullerenes w/trapped Noble Gases at Graphite Peak, Antarctica

Impact Site for the PTB?