Presence of an iron-rich nanophase material in the upper layer of the Cretaceous-Tertiary boundary clay
Abstract
We report new geochemical evidence from ten Cretaceous-Tertiary boundary sites in North America and Europe, indicating the presence of a material remnant of a large asteroid or comet that struck the Earth at 65.0 Ma. Mössbauer spectroscopic data reveals that a ubiquitous iron-rich nanophase material exists at the uppermost part of the K-T boundary layer in the Western Hemisphere and in Europe in marine and continental fine-grained sedimentary rock. The high surface-to-volume ratio of nanophase material suggests that it may be the carrier of the iridium abundance enhancement that marks the K-T boundary. Even more provocative is the possibility that the discovered nanophase material is, for the most part, composed of the vaporized impactor after the impact-generated high-temperature vapor plume rose and cooled above the atmosphere.
- Publication:
-
Meteoritics and Planetary Science
- Pub Date:
- January 2001
- DOI:
- 10.1111/j.1945-5100.2001.tb01814.x
- Bibcode:
- 2001M&PS...36..123W