Traces of a large asteroid that fell to Earth 780 thousand years ago were found in Laos

Table of contents:

Traces of a large asteroid that fell to Earth 780 thousand years ago were found in Laos
Traces of a large asteroid that fell to Earth 780 thousand years ago were found in Laos
Anonim

Geologists discovered a large gravitational anomaly on the territory of Laos, indicating the existence of a giant twenty-kilometer crater that arose about 780 thousand years ago as a result of the fall of a large asteroid. The results of observations and conclusions of scientists were published in the journal PNAS.

"The crater and the consequences of the most recent fall of a large asteroid were hidden from us for almost a century. We found four evidence at once that this excavation and other traces of this event are hidden under young lava deposits in southern Laos," the scientists write.

The interior and surface of the Earth, unlike the Moon, Mars, Mercury and other worlds of the inner solar system, are not immutable. They are constantly renewed due to the rotation of rocks between the crust and the inner layers of the lithosphere, as well as the action of various sources of erosion, including wind and water.

Therefore, on our planet there are almost no traces of the fall of even the largest asteroids capable of destroying life on Earth. This prevents scientists from understanding how their falls could have influenced the formation and evolution of life, as well as how often they occurred, the nature and characteristics of these falls.

For this reason, the discovery of new craters becomes a big event for geologists. For example, four years ago in Australia, the largest crater in the history of our planet's existence was discovered, with a diameter of 400 km. His discovery caused a lot of controversy, since 300 million years ago, when this "guest from space" supposedly fell, there were no mass extinctions on Earth.

Brad Singer, professor of geochronology at the University of Wisconsin in Madison (USA), and his colleagues have been trying for many years to solve a similar riddle related to the supposedly most recent fall of a large asteroid on Earth.

Help from space

Back in the late 1930s, geologists discovered on the shores of Australia and the countries of Southeast Asia deposits of the so-called tektites - drop-shaped stones, presumably resulting from the fall of large asteroids. Deposits of such rock fragments, ejected from the Earth's surface after the impact of a meteorite, were subsequently discovered in other parts of Eurasia. In total, they cover 10 to 30% of the total area of the planet.

Despite decades of searching, geologists have not been able to figure out exactly where the "progenitor" of these deposits fell, what size it possessed and what consequences it could cause. Only the approximate date of the fall of this asteroid is known - 780 thousand years ago, as well as about 20 candidates for the role of a crater, whose size and structure are radically different from each other.

Singer and his colleagues found the answer to this question using clues from space. Scientists did not conduct excavations or look for partially erased traces of craters on geological maps, but analyzed how gravitational anomalies are distributed throughout Asia.

The fact is that the formation of the crater and its filling with light sedimentary or heavy volcanic rocks should have generated special distortions in the Earth's gravitational field, distinguishing this hidden excavation from the surrounding rocks. Guided by this idea, scientists began to look for similar anomalies and study the chemical and mineralogical composition of rocks on their territory.

These searches indicated the existence of a crater with a diameter of about 20 km in the south of Laos, on the territory of the Bolaven Plateau, filled with lava and debris of sedimentary rocks. Analysis of its contents showed that it consists of the same minerals as tektites, and not far from the crater, scientists found traces of rocks that were deformed as a result of a powerful impact.

Further study of this crater, as geologists hope, will help to find out what size the asteroid that gave birth to it had, and also to find out with what speed and at what angle it fell to the surface of the Earth. All this will allow for the first time to accurately assess what role his fall played in the dispersal of ancient upright people (Homo erectus) across Asia, whose oldest remains date back to the same era as this catastrophe.

Recommended: