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Shock-induced devolatization of calcium sulfate and implications for K-T extinctionsCalcium 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.
Document ID
19950012618
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Chen, Guangqing
(California Inst. of Tech. Pasadena, CA, United States)
Tyburczy, James A.
(Arizona State Univ. Tempe, AZ., United States)
Ahrens, Thomas J.
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 6, 2013
Publication Date
November 22, 1993
Subject Category
Environment Pollution
Report/Patent Number
NAS 1.26:197608
CONTRIB-5350
NASA-CR-197608
Accession Number
95N19033
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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