A sediment layer in eastern Hokkaido contains unusual platinum-group element concentrations, hinting at a major impact event at the end of the Cretaceous.
In Hokkaido Prefecture, Japanese scientists discovered traces of an asteroid impact that could have triggered the mass extinction of the dinosaurs at the end of the Cretaceous period, about 66 million years ago.
Researchers from Tohoku University, the University of Tokyo, and Fukui Prefectural University reported that the layer in eastern Hokkaido is the first confirmation of such traces in Japan.
An asteroid 10–15 km in diameter is believed to have fallen in the area of the modern Yucatán Peninsula in Mexico, and is considered one of the causes of the dinosaurs’ extinction, linked to a sharp global cooling.
Evidence of asteroid impacts is found in various regions of the world in layers with elevated concentrations of platinum-group elements, which are characteristic of an object that fell at the boundary between the Cretaceous and Paleogene periods.
Key conclusions and future research
Over ten years, Professor Rei Takashima from Tohoku University, along with colleagues, studied the Nemuro Group, located in the city of Urakawa on Hokkaido.
The Nemuro Group is a large complex of sedimentary and volcanic rocks from the Late Cretaceous and Early Paleogene periods, located on the eastern part of Hokkaido.
Although this discovery strengthens understanding of the role of impact events in the final stages of Earth’s biodiversity at the end of the Cretaceous, the research continues to more precisely determine the dates and magnitudes of the event and its impact on various ecosystems around the planet.
New data help to better understand the connection between impact events and changes in life on the planet at the Cretaceous–Paleogene boundary, underscoring the importance of further studies for Earth’s history.
AloJapan.com