Detecting traces of life in a 375 million-year-old meteor crater

The 52km-diameter impact crater caused by meteorites crashed into Earth became a favorable habitat for ancient microorganisms.

The team at Linnaeus University analyzed rock samples taken from the Siljan crater, or Siljan Ring, Europe’s largest impact crater with a diameter of about 52km, IFL Science reported on October 23. This crater formed about 375 million years ago, when a large meteorite crashed into the land of present-day Sweden.

Detecting traces of life in a 375 million-year-old meteor crater
Small crystals were found in rock samples under the Siljan crater. (Photo: Henrik Drake).

The rock sample contains small crystals of calcium carbonate (CaCO 3 ) and sulfide , most likely formed by microbial activity. “The fact that the mineral sample contains relatively many different carbon and sulfur isotopes shows that this place used to exist microorganisms that produce and consume greenhouse gases as well as reduce sulfate to sulfide,” said Henrik Drake, author of the study. main of the study, said.

The team of scientists used radioisotope dating to find out when microorganisms started to become active. The resulting crystals formed 80-22 million years ago, meaning life appeared in the Siljan crater about 300 million years after the meteorite crashed.

Life exists not only on the surface of the Earth but also hidden underground, in the deep biosphere. The habitat of these creatures is often thought to be caused by meteorite impacts. That proves, if there are living things on other planets, they may also appear thanks to meteorites. Such collisions help life thrive by creating holes for microorganisms to live inside and regulating hydrothermal convection.

A thorough understanding of microbial life at impact craters leads to many inferences in the field of astrobiology, said study co-author Magnus Ivarsson. “Our findings help confirm that the impact crater is a favorable habitat for microorganisms on Earth, and possibly even elsewhere in space,” added Drake.