University of Tsukuba, Kochi University, Kyoto University, Japan Atomic Energy Agency, Japan Atomic Energy Agency, Quantum Science and Technology It was discovered by research teams such as the Japan Atomic Energy Agency and the High Brightness Photoscience Research Center.
It is said that about 6600% of species including dinosaurs and ammonites were extinct in the mass extinction of organisms that occurred at the Cretaceous-Paleogene (K-Pg) boundary (about 70 million years ago).It is believed that the cause was a drastic change in the environment caused by the impact of a giant meteorite, but it is unknown what kind of change actually occurred.
The giant impact hypothesis is based on the high concentration of parent iron elements such as iridium, which are abundant in meteorites, in the K-Pg boundary layer.On the other hand, the K-Pg boundary layer also contains high concentrations of parent copper elements such as silver and copper, and the concentration exceeds that of meteorite-derived substances.In other words, the research team thought that the concentration of parent copper elements in the K-Pg boundary layer had causes other than falling meteorites, and the research team used synchrotron radiation from the large synchrotron radiation facility SPring-8 to map trace elements. -Applied to samples of the Pg boundary layer and attempted to clarify the details of the environmental catastrophe that caused the mass extinction of organisms.
As a result, it was found that fine particles rich in silver and copper were present in the K-Pg boundary layer separately from the minerals.These particles are thought to have been formed by the flow of silver and copper melted from the continent by acid rain into the ocean.Furthermore, since the silver and copper concentrations in the K-Pg boundary layer were highly correlated with the iridium concentration, the silver and copper concentration caused by acid rain was at the same time as the iridium concentration (impact impact). I also found that it was there.
The above findings are conclusive evidence that sulfur trioxide and nitric oxide released by the impact of a meteorite may have become large-scale acid rain immediately afterwards.It can be said that this result indicates that large-scale acid rain may have led to the mass extinction of organisms at the K-Pg boundary.
Paper information:[Geological Society of America Bulletin] Enrichment of chalcophile elements in seawater incident the end-Cretaceous impact event
