Extraterrestrial Cause for the Cretaceous-Tertiary Extinction

@article{Alvarez1980ExtraterrestrialCF,
  title={Extraterrestrial Cause for the Cretaceous-Tertiary Extinction},
  author={Luis W. Alvarez and Walter Alvarez and Frank. Asaro and Helen V. Michel},
  journal={Science},
  year={1980},
  volume={208},
  pages={1095 - 1108}
}
Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of… 

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The discovery of iridium anomalies in three Cretaceous-Tertiary sections by the Alvarez team in 1980 prompted them to hypothesize an asteroid impact to explain these unusual concentrations. In the

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TLDR
It is found that unexpectedly constant fallout of extraterrestrial matter to Greenland occurred during the Holocene, whereas a greatly enhanced input of terrestrial iridium and platinum masked the cosmic flux in the dust-laden atmosphere of the last glacial age.

The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary

TLDR
Records of the global stratigraphy across this boundary are synthesized to assess the proposed causes of the Cretaceous-Paleogene boundary and conclude that the Chicxulub impact triggered the mass extinction.

The extraterrestrial component in marine sediments: Description and interpretation

  • F. Kyte
  • Geology, Environmental Science
  • 1988
The influx of extraterrestrial matter to the Earth is dominated by two size-fractions: sub-millimeter interplanetary dust and impacting asteroids and comets. Over geologic time the major contribution

A Major Meteorite Impact on the Earth 65 Million Years Ago: Evidence from the Cretaceous-Tertiary Boundary Clay

TLDR
The major extinction of life on the earth at the end of the Cretaceous Period may be related to the meteorite impact, as the enriched noble metals in the clay are present in cosmic proportions, indicating that the impacting celestial body had not undergone gross chemical differentiation.
...

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