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 platinum group nuggets in deep-sea sediments
Iron cosmic spheres, composed of iron oxides surrounding a FeNi metal core, were discovered more than a century ago during the voyage of the HMS Challenger1. That tbe spheres originated by
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.
An extraterrestrial impact at the Permian-Triassic boundary?
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Impact production of C02 by the Cretaceous/Tertiary extinction bolide and the resultant heating of the Earth
EVIDENCE at the Cretaceous/Tertiary boundary suggests that the proposed 'extinction' bolide1 struck a continental or shallow marine terrane. This evidence includes: shocked quartz and feld-spar
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.


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.