Dinosaur-Killing Asteroid Created A Hydrothermal Province Nine Times The Size Of Yellowstone

Remains of an ancient hydrothermal vent system have been discovered beneath the crater whose making ended the Cretaceous era. The system is nine times the size of the Yellowstone Caldera, sometimes referred to as a supervolcano, testifying to the enormous damage the impact wrecked on the Earth’s crust. The scientists who discovered the extinct vents think it might even reveal how life began.

Aside from its role in ending the dinosaur’s planetary dominance, the Chicxulub crater, the largest impact basin with an intact peak ring left on Earth, makes a tempting target for geologists. The International Ocean Discovery Program drilled 1,335 meters (0.8 miles) into the crater to study how the Earth's crust responds to being hit with such force.

In Science Advances, a large team of researchers describe a system where hot volcanic fluids circulated to a depth of at least 700 meters (0.4 miles) – far exceeding what had been found by previous expeditions, which barely scratched the surface relatively speaking. Many of the paper’s authors were also part of this week's announcement that the asteroid's angle of approach was crucial to the damage it caused, with either a steeper or shallower angle possibly leaving many more species alive.

The researchers reconstructed conditions after the strike from the composition of the rocks. Temperatures must have been above 300ºC (570ºF) for a long time to allow the dispersal of some substances through the system. Iron-rich rocks reveal changes in the Earth’s magnetic field, showing it took around 2 million years for the crust beneath the central peak to cool to 90ºC (194ºF).

Networks of porous rocks were left behind, perfect for thermophilic microorganisms to colonize during the slow cooling.

The paper notes traces of a similar extinct hydrothermal system have been found beneath the Sudbury Structure, the remains of a 1.85-billion-year-old crater. The authors think the Vredefort structure, the largest and oldest crater of the three, probably once had something similar.

On a planet recently teeming with life, the spread of single-celled organisms through the embers of an ancient Mount Doom probably had little impact elsewhere. However, the paper notes that during the Hadean Era “the entire surface of Earth was affected by ~6,000 impactors larger than the ~10-km Chicxulub impactor.”

The Earth’s crust was thinner and hotter then, and the authors calculate there would have been around 200 craters between 1,000 and 5,000 kilometers (621 and 3,100 miles) across. Each of these would have had water-rich, high-temperature zones, which gradually contracted towards the center, well suited to being homes to heat-loving organisms. These temperatures would also have driven chemical reactions, providing potential energy sources for emerging life forms. All this may have created the stage for the appearance of the first living things, the paper proposes, some of which adapted to life at the surface when their first home cooled. If so, the crust beneath large impact craters may be a good place to seek life on Mars.