Shock-induced devolatization of calcium sulfate and implications for K-T extinctions

By: Nasa, National Aeronautics and Space Adm

Calcium sulfate devolatization during the impact at Chicxulub, Mexico and dispersal in the stratosphere of the resultant sulfuric acid aerosol have been suggested as a possible mechanism for the Cretaceous-Tertiary extinctions. In this paper, we investigated two shock-induced devolatization reactions of calcium sulfate up to 42 GPa in the laboratory: CaSO4 + SiO2 yields CaSiO3 + SO3(degassed) and CaSO4 yields CaO + SO2(degassed) + 1/2 O2(degassed). We found both to proceed to a much less extent than calculated by equilibrium thermodynamic calculations. Reaction products are found to be 10(exp -2) times those calculated for equilibrium. Consequently our estimate of the amount of sulfur oxides degassed into the atmosphere from shock devolatization of CaS04 in the Chicxulub lithographic section (6x10(exp 15)-2x10(exp 16)g in sulfur mass) is lower by a factor of 70 to 400 than previous estimates; the related environmental stress arising from the resultant global cooling of approximately 4 K and fallout of acid rain does not appear to suffice to explain the widespread K-T extinctions. Chen, Guangqing and Tyburczy, James A. and Ahrens, Thomas J. Unspecified Center ...

• Format: Paperback
• Language: English
• ISBN: 1728995264
• ISBN13: 9781728995267
• Release Date: January 1
• Publisher: Independently Published
• Length: 32 Pages
• Weight: 0.22 lbs.
• Dimensions: 0.1" x 8.5" x 11.0"