Search results
Results From The WOW.Com Content Network
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.
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.
Located in Tunisia, the contact is described as a reddish layer at the base of a dark clay layer. This reddish layer is the Iridium Anomaly, representative of the fallout of the major impact that resulted in the mass extinction event that ended the Cretaceous.
Gravity anomaly, difference between the observed gravity and a value predicted from a model Bouguer anomaly, anomaly in gravimetry; Free-air anomaly, gravity anomaly that has been computed for latitude and corrected for elevation of the station; Iridium anomaly, an unusual abundance of what is normally a very rare element in the Earth's crust
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 ...
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 ...
where [] is the normalized concentration of the element whose anomaly has to be calculated, [] and [+] the normalized concentrations of the respectively previous and next elements along the series. The rare-earth elements patterns observed in igneous rocks are primarily a function of the chemistry of the source where the rock came from, as well ...
The Danian is the oldest age of the Paleocene, defined at its base by the K-Pg boundary. It is very important because the readily recognized iridium anomaly and primitive Danian planktonic foraminifers define the base of the Danian. Danian foraminiferans repopulated the Paleocene seas after the Cretaceous mass extinction (Olsson et al., 1996).