An immense collision of asteroids took place in the Solar System some 500 million years ago
Four million years after the breakup of a giant asteroid, the Earth experienced a massive bombardment of meteorites. Bombardment from space at that time was 100 times as powerful as what our planet experiences nowadays. Parts of these meteorites have been found in limestone sediments in Sweden. They all contain a typical composition of minerals that allows one to identify them as a part of a giant asteroid, which was broken apart as a result of a collision with another giant rock. This was said by scientists from Rice University (USA) and Gцteborg University (Sweden), who had studied the sediments in desolate quarries in Sweden.
Nowadays, one meteorite a year falls on a territory of 20,000 sq. km. However, research conducted by American and Swedish scientists found a 100-fold increase in meteorite activity during the period when the limestone was forming in Sweden. This happened a bit less than 500 million years ago. The scientists have found more than 40 such ancient meteorites on the 390,000 sq. km. search area. The meteorites are up to 20 cm in size. A unique extraterrestrial form of the mineral chromite has been found in all of those meteorites.
American and Swedish scientists believe that a huge asteroid was part of one of the largest collisions that occurred in the later history of the Solar System. The fragments of the huge asteroid make up some 20 percent of all meteorites that fall down on the Earth's surface nowadays. Ancient meteorites containing extraterrestrial chromite can be theoretically found in limestone sediments all over the world. Now, scientists are going to study limestones in China.