Slow sedimentation and Ir Anomalies at the Cretaceous-Tertiary Boundary

Bruns, Peter, Rakoczy, H., Pernicka, E. and Dullo, Wolf-Christian (1997) Slow sedimentation and Ir Anomalies at the Cretaceous-Tertiary Boundary Geologische Rundschau, 86 . pp. 168-177.

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Iridium enrichments, at or close to the K/T
boundary, are often cited as evidence for impacts of
cosmic bodies or volcanic events, or both, that resulted
in mass extinctions. A third possible explanation for the
high Ir concentrations, that the enrichments were
caused by the cosmic micrometeorite flux during times
of slow Sediment accumulation, has generally been rejected.
In this study we examine the Ir/Au ratios and
conclude that they may indicate enrichment of siderophile
elements by slow sedimentation. In addition,
the concept of slow sedimentation at the K/T boundary
is consistent with many aspects of the K/T boundary
research such as the gradual decline of the species
before the major extinction level and recent reports of
faunal transitions from Cretaceous to Tertiary without
sudden extinctions, hiatuses or Ir anomalies.

Document Type: Article
Keywords: K/T boundary ; Ir ; Ir/Au ratios ; Slow sedimentation ; Extinctions
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
ISSN: 0016-7835
Projects: ODP
Date Deposited: 18 Feb 2008 17:23
Last Modified: 21 Mar 2018 08:38

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