After all, fine dust suspended in the atmosphere may have played an important role in the extinction of dinosaurs. About 66 million years ago, a space rock larger than Mount Everest is believed to have crashed into the coast of present-day Mexico, triggering a series of cataclysms that eventually killed three-quarters of life on Earth, especially non-avians. dinosaurs

But the finer details of how all this came to be are still being debated. Now scientists have uncovered a geological “black box” that suggests the asteroid impact created a fine cloud of dust that blocked sunlight, cooled the Earth, halted photosynthesis and disrupted the food chain.

The hypothesis, first proposed as a mechanism by geologists who discovered the first signs of a major impact in 1980, was disproved in the early 2000s because rock samples from that period did not contain enough fine dust to cause a global winter. However, most previous studies were based on one-centimeter-thick sediment layers from the Cretaceous-Paleogene period. (There’s not much dirt to get your teeth into.)

This new study analyzed 40 sediment samples from a much richer deposit at a depth of 1.3 meters in Tanis, North Dakota. The site is located 3,000 kilometers (about 1,900 miles) north of the Chicxulub asteroid crater, but offers a unique picture of how clouds of dust, soot and particles spread in the years after the impact.

Larger particles scatter light at smaller angles than smaller particles; Thus, using a laser, the researchers were able to determine how much of each sample consisted of fine silicate powder ranging from 0.8 to 8 micrometers across.

“[Ми виявили] Fine dust makes a larger contribution than previously estimated, the researchers wrote.

Using computer simulations, researchers found that this fine dust, created when the asteroid hit Earth and crushed the rock beneath it, was the “most lethal” of the particles released when the 10- to 15-kilometer-wide asteroid hit Earth. Soil. They found that high levels of dust in the atmosphere could make it impossible for plants to photosynthesize, creating global darkness that would last almost two years.

Without plants, the entire food chain would collapse. The most popular predators, e.g. Tyrannosaurus rexThey hunted prey that depended on plants as part of their diet. This dust could remain suspended in the air for up to 15 years, blocking sunlight, causing global temperatures to drop by 15°C and “photosynthesis to cease for almost two years after the impact,” the researchers wrote.

The shock of the impact may also have vaporized the rock and produced sulfur-containing gases that formed fine particles in the upper atmosphere. The intense heat created by the collision with the asteroid may have caused massive wildfires, releasing large amounts of soot and ash into the sky. However, according to the results of the researchers, the main cause of the long winter on the planet was not substances such as sulfur particles, but small silicates.

“We found that global darkness and loss of long-term photosynthetic activity of the planet occurred only in the silicate dust scenario, approximately 1.7 years (620 days) after the impact,” the researchers wrote. he wrote.

“This is a long enough period of time to create serious problems for both terrestrial and marine habitats.”

Animals and plants that cannot or do not adapt to the darkness and cold die. Flora and fauna with flexible diets, habitats and lifestyles will have a better chance of survival. The Chicxulub asteroid impact also triggered a 1.5 kilometer mega tsunami that struck all of Earth’s continents and caused seismic activity 50,000 times stronger than the 2004 Sumatra earthquake. Source