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The type locality of this iridium anomaly is near Raton, New Mexico. [1] [2]Iridium is a very rare element in the Earth's crust, but is found in anomalously high concentrations (around 100 times greater than normal) in a thin worldwide layer of clay marking the boundary between the Cretaceous and Paleogene periods, 66 million years ago.
In 1980, a team of researchers led by Nobel prize-winning physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Vaughn Michel, discovered that sedimentary layers found all over the world at the Cretaceous–Paleogene boundary (K–Pg boundary, formerly called Cretaceous–Tertiary or K–T boundary) contain a concentration of iridium hundreds of times ...
The Alvarezes, joined by Frank Asaro and Helen Michel from University of California, Berkeley, published their paper on the iridium anomaly in Science in June 1980. [8] Almost simultaneously Jan Smit and Jan Hertogen published their iridium findings from Caravaca, Spain, in Nature in May 1980. [11]
He is best known as the chemist who discovered the iridium anomaly in the Cretaceous–Paleogene boundary layer that led the team of Luis Alvarez, Walter Alvarez, Frank Asaro, and Helen Michel to propose the Asteroid-Impact Theory, which postulates that an asteroid hit the Earth sixty-five million years ago and caused mass extinction during the ...
A really bad day: Dino-killing asteroid and the iridium anomaly. While paleontologists have studied fossils for centuries, the science of mass extinction is relatively new. Radiometric dating ...
An iridium anomaly at the boundary is consistent with this hypothesis. However, analysis of the boundary layer sediments failed to find 244 Pu, [32] a supernova byproduct [clarification needed] which is the longest-lived plutonium isotope, with a half-life of 81 million years.
The Eltanin impact has been confirmed (via an iridium anomaly and meteoritic material from ocean cores) but, as it fell into the Pacific Ocean, apparently no crater was formed. The age of Silverpit and the confirmed Boltysh crater (65.17 ± 0.64 Ma), as well as their latitude , has led to the speculative hypothesis that there may have been ...
Iridium is extremely rare in Earth's crust because it is a siderophile element which mostly sank along with iron into Earth's core during planetary differentiation. [12] Instead, iridium is more common in comets and asteroids. [8] Because of this, the Alvarez team suggested that an asteroid struck the Earth at the time of the K–Pg boundary. [12]