The cometary breakup hypothesis re-examined

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Author: La Violette, Paul. A.
• Format: Text
• Language: English
• Published: Oxford University Press 1987
• Subjects: Articles; East Antarctica; Napier; Tunguska; Antarc*; Antarctica; ice core
• Online Access: http://mnras.oxfordjournals.org/cgi/content/short/224/4/945; https://doi.org/10.1093/mnras/224.4.945

The theory that a Chiron-like progenitor of both Comet Encke and the Tunguska cosmic body may have fragmented beginning around 22 000 years <scp>BP</scp> and that debris from this breakup was responsible for producing the high heavy metal concentrations observed in the Late Wisconsin stage polar ice is shown to be incorrectly founded. This paper re-examines the geochemical comparison which Clube & Napier make between the composition of the Tunguska cosmic body and elemental abundances previously reported for a sample of Sn-rich dust retrieved from the Wisconsin section of the Camp Century ice core. No evidence is found that would link these two sources to a common origin. Thus the hypothesis that a cometary breakup was responsible for modulating the Earth's climate and perpetuating the last ice age is unfounded. On the other hand, evidence is presented indicating that debris from the Tunguska explosion may be present in a firn layer at Dome C, East Antarctica. Analysis of the geochemical data for this stratum leads to an estimate of <f>${10}^{6}-{10}^{7}$</f> t for the mass of the Tunguska body, in approximate agreement with previous determinations.