The report that Cretaceous/Tertiary (K/T) boundary sediments are greatly enriched in iridium (Ir) has generated an intense controversy concerning the origin of this signal. Although convincing evidence suggests that the Ir anomaly was generated by the collision of a large bolide with the Earth, other explanations claim that extensive, violent volcanism can account for the Ir spike. We have recently found that K/T boundary sediments at Stevns Klint, Denmark contain two amino acids which are exceedingly rare on the Earth, but which are some of the most abundant amino acids in carbonaceous meteorites. An extraterrestrial source is the most reasonable explanation for the presence of these amino acids. Many questions have been raised by our preliminary study. Are these extraterrestrial amino acids present in other K/T boundary sediments? How do we explain the large amounts of extraterrestrial amino acids in the K/T boundary sediments? Why is the extraterrestrial amino acid signal absent in the Stevns Klint boundary clay, but present directly above and below? In order to answer these questions we will examine other K/T boundary sequences for amino acids; stable isotope analyses will be performed on the isolated amino acid fractions to further demonstrate their extraterrestrial origin; sediments of different ages and depositional environments will be analyzed to determine whether there is a measurable terrestrial production of these amino acids; we will investigate whether other extraterrestrial amino acids are present in K/T boundary sediments; and experiments will be conducted to evaluate the survivability of extraterrestrial amino acids both during impact and after deposition. These analyses will enable us to ascertain the global distribution of the extraterrestrial amino acid signal, what processes may have subsequently disturbed these amino acids, and what kind of object or processes supplied this unique organic cosmochemical signal.
