A Short Duration of the Cretaceous-Tertiary Boundary Event: Evidence from Extraterrestrial Helium-3

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Science  09 Mar 2001:
Vol. 291, Issue 5510, pp. 1952-1955
DOI: 10.1126/science.291.5510.1952

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Analyses of marine carbonates through the interval 63.9 to 65.4 million years ago indicate a near-constant flux of extraterrestrial helium-3, a tracer of the accretion rate of interplanetary dust to Earth. This observation indicates that the bolide associated with the Cretaceous-Tertiary (K-T) extinction event was not accompanied by enhanced solar system dustiness and so could not have been a member of a comet shower. The use of helium-3 as a constant-flux proxy of sedimentation rate implies deposition of the K-T boundary clay in (10 ± 2) × 103 years, precluding the possibility of a long hiatus at the boundary and requiring extremely rapid faunal turnover.

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