June 19, 2024

The cosmic influence is dated - wissenschaft.de

The cosmic influence is dated – wissenschaft.de

Much earlier than thought: the huge Hiawatha crater formed under the ice of Greenland 58 million years ago, and therefore not only when humans actually existed, as previously assumed. This stems from analyzes of rocky material formed during the asteroid impact. The new dating now raises questions about the effects of hell on the world at the time. Scientists say more ideas could lead to a better understanding of Earth’s evolution in the post-dinosaur era.

Again and again there was an infernal rift: many asteroids struck our planet in the course of Earth’s history and caused local or far-reaching consequences. The most famous example is the massive impact that knocked dinosaurs out of evolution some 66 million years ago. Witness this strike on the massive remains of the Chicxulub crater in the Mexican Yucatan Peninsula. In addition to this particularly large scar, other scars of large dimensions are also known. However, a particularly amazing crater was discovered only in 2015: the structures of Hiawatha crater were only revealed by a radar investigation, because it was sleeping under a thick layer of ice in northwest Greenland.

How old is the hole under the ice?

According to investigations, the diameter of Hiawatha crater is about 31 kilometers – which makes it one of the 25 largest known craters on Earth. It stands to reason that the impact once had far-reaching consequences for Earth’s climate. But when did that happen? So far, relatively little weathering structures have suggested that the crater is still small. This has led to some speculation: it seemed possible that the asteroid collided with Earth only 13,000 years ago. So they may have been responsible for the nearly 1,000-year global cooling known as the Younger Dryas, one speculates.

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But as the new historiography indicates, the Hawatha effect may not have been a glacial climatic factor that might also have influenced the fate of our ancestors. The international research team’s findings are based on analyzes of sand and rock that have been highlighted by water flowing from beneath the surface of the glacier in the crater area. “Since we discovered the crater seven years ago, we have worked hard so far. We have made several field trips to the area to collect samples related to the Hiawatha impact,” says co-author Nikolai Larsen of the University of Copenhagen. Specifically, the samples being examined now are material that arose directly from the impact.

It crashed 58 million years ago

As the researchers explain, the temperature rise and shock-like melting led to changes in some materials that allow temporal classification by defining decomposition processes. An argon-based study was carried out in sand at the Natural History Museum of Denmark in Copenhagen – History 40Ar/39Ar. At the same time, the mineral zircon in rock samples was exposed to determine the history of uranium and lead at the Swedish Natural History Museum in Stockholm.

As the researchers report, the results of both approaches point to the Paleocene – specifically to the time about 58 million years ago. This means that the Hiawatha crater is much older than previously thought. “The result of age determination surprised us all,” says lead author Gavin Kenny of the Swedish Museum of Natural History. “Since the two laboratories came to the same conclusion with different methods of dating, I am satisfied that we determined the actual age of the crater,” says his colleague Michael Storey of the Natural History Museum in Denmark.

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The new history now also shows the conditions under which the impact occurred: when the asteroid Hiawatha slammed into the Earth’s surface, the area in what is now northwest Greenland was not covered by a one-kilometer-thick layer of ice. The researchers said that temperatures were rather mild there, and the area was full of forests and animals. The life world of our planet was just recovering from the catastrophic effects of the Chicxulub effect, which occurred eight million years ago.

Although the impact of Hiawatha was far from being of such magnitude, it certainly devastated the area and may have had far-reaching effects on Earth’s climate and wildlife. However, no obvious effects of such an effect could yet be detected. But it may come true: Scientists say further investigations may show ancient environmental and climate consequences to bear in the future.

Source: University of Copenhagen – Faculty of Science, professional article: Science Advances, doi: 10.1126/sciadv.abm2434