Extraterrestrial Cause for the Cretaceous-Tertiary Extinction

  title={Extraterrestrial Cause for the Cretaceous-Tertiary Extinction},
  author={Luis W. Alvarez and Walter Alvarez and Frank. Asaro and Helen V. Michel},
  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… 

Extraterrestrial iridium, sediment accumulation and the habitability of the early Earth's surface

We have measured the concentrations of iridium and platinum in ancient metasediments from Akilia Island, southern West Greenland, to obtain the first direct constraints on the extraterrestrial mass

Extraterrestrial amino acids in Cretaceous/Tertiary boundary sediments at Stevns Klint, Denmark

K/T boundary sediments at Stevns Klint, Denmark, contain both α-amino-isobutyric acid and racemic isovaline, two amino acids that are exceedingly rare on the Earth but which are major amino acids in carbonaceous chondrites, suggesting that an extraterrestrial source is the most reasonable explanation for the presence of these amino acids.

The flux of extraterrestrial matter to Earth as recorded in Paleogene and Middle Ordovician marine sediments

This thesis aims at reconstructing events in the solar system, mainly collisional events in the asteroid belt, by searches for extraterrestrial minerals in Paleogene and Middle Ordovician marine

Iridium Anomaly in the Upper Devonian of the Canning Basin, Western Australia

A moderate iridium anomaly, about 20 times the local background, has been found in Upper Devonian rocks in the Canning Basin, which suggests a causal link with some form of meteoroid impact.

Iridium abundance maxima in the Upper Cenomanian extinction interval

Two iridium abundance peaks, both 0.11 ppb (whole-rock basis) over local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado. They occur just below the

The Impact at the Cretaceous/Tertiary Boundary

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

Meteoric smoke fallout over the Holocene epoch revealed by iridium and platinum in Greenland ice

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

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

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.



Faunal Extinctions and Reversals of the Earth's Magnetic Field

A study of 28 deep-sea piston cores from high and low latitudes shows that during the last 2.5 m.y. eight species of Radiolaria became extinct. Prior to their extinction these species were widely

Terminal Cretaceous Events

  • T. Worsley
  • Geology, Environmental Science
  • 1971
SEVERAL explanations have been offered (see refs. 1–3) for the abrupt faunal extinctions at the end of the Cretaceous and, with the advent of the JOIDES Deep Sea Drilling Project, it was hoped that

Catastrophic chemical events in the history of the ocean

Catastrophic chemical events are characterised by sharp rises in δ34S in the surface of the whole world ocean, and by greater overshoots locally. Three events are recognised and named for the

Silicate Spherules from Deep-Sea Sediments: Confirmation of Extraterrestrial Origin

One silicate spherule has been identified as definitely extraterrestrial since its abundances of nonvolatile trace elements closely match those of primitive solar system material.

The Enigma of the Extinction of the Dinosaurs

One of the more interesting contributions of paleontology to general knowledge is evidence that giant reptiles were once the dominant life forms on our planet. During the past two centuries some 5000

Late Cretaceous geomagnetic polarity sequence: detailed rock and palaeomagnetic studies of the Scaglia Rossa limestone at Gubbio, Italy

Summary. A magnetic polarity sequence has been developed for the Late Cretaceous from about 500 stratigraphic samples of the Scaglia Rossa limestone from a 250-m thick section near Cubbio, Italy.

Reversals of the Earth's magnetic field and climatic changes

IT has been suggested that evolution may be influenced by reversals of the Earth's magnetic field1–3. It was observed that there were correlations between discontinuities in microfossil assemblages