Cambrian Sinsk: Mountain Building Phenomenon 500 Million Years Ago Contributed to Mass Extinction Event via Tectonic Plates [Study]

The Cambrian explosion, also called the Cambrian radiation or Cambrian diversification, is an event that occurred more than 500 million years ago. It is a period when the majority of major animal groups began to appear in the fossil record. According to scientists, the event was attributed as an "explosion" since it happened in a short period of time in a geologic time scale, specifically within a span of 20 million years.

However, recent evidence sheds light on this burst of animal evolution, suggesting that the Cambrian event was short-lived since an unprecedented major extinction event also took place at that time. According to a new study earlier this year, ancient tectonic plates gradually crashed into each other, resulting in the buildup of mountains called the "mountain building" phenomenon, contributing to the extinction.

The new research paper called this natural disaster as the "Sinsk event extinction" or the "Cambrian sinsk event." It was triggered by a violent movement of tectonic plates, as well as a crustal narrowing at the edge of the supercontinent of Gondwana, which formed 600 million years ago. Yet, this mass extinction event paved the way for the emergence of new lifeforms on the planet later on.

Cambrian Explosion

The 'explosive' emergence and evolution of animals during the Cambrian geologic period, which spanned around 540 million to 485 million years ago, was a monumental event in Earth's biology. Still, the circumstances behind it have largely remained a mystery. In 2019, the Natural History Museum (NHM) in the United Kingdom reported that the Cambrian explosion was significantly shorter than previously thought.

By studying fossil records of trilobites, which are extinct marine animals, Dr. Greg Edgecombe at NHM confirmed that the burst of evolution during the Cambrian period only lasted for around 20 million years. Although there had been a multitude of research about when the Cambrian explosion started, there is limited effort and data on when this explosive evolution ended, according to the NHM.

Cambrian Sinsk Event Extinction

To address this Cambrian puzzle half a decade later, an international team of researchers led by the United States and Australia published a study in the journal Science Advances on March 29. In their paper, researchers revealed that the potential end or extinction during the Cambrian explosion was triggered by tectonic plates, in a phenomenon called Cambrian Sinsk event extinction, as mentioned earlier.

Involving a series of mountain buildings, the crashing, and interaction of tectonic plates over 500 million years ago further pushed magma into Earth's surface. This process paved the way for the entry of greenhouse gases into the planet's atmosphere and caused rapid climate change.

Reports about the findings on this mass extinction event suggest this even decimated several animal groups, including reef-building marine sponges called archaeocyathids and conical shell-equipped animals called hyoliths. The research started during the 1990s based on data collected in Antarctica and southern Australia.