May 8 (UPI) — New research shows mineral weathering during hothouse conditions helped life on Earth rebound in the wake of one of the “big five” mass extinctions some 200 million years ago.
The asteroid impact and uptick in volcanic activity that wiped out most of life also triggered a dramatic rise in atmospheric CO2 concentrations. These hothouse conditions promoted acidic water that worked to weather exposed bedrock.
Water reacts with minerals in bedrock to form new minerals, like clay mineral illite. The process is called chemical weathering, and it occurs more rapidly when water becomes more acidic.
Until recently, scientists have struggled to date evidence of ancient chemical weathering. But the latest findings — detailed in the journal Nature Communications — show significant chemical weathering occurred during the Late Triassic period roughly 200 million years ago.
“We have managed to precisely date deeply weathered crystalline bedrock from the North Sea and across Scandinavia, which then was part of the supercontinent Pangea,” Jochen Knies, researcher with the Geological Survey of Norway, said in a news release. “We did this by detailed geomorphological and mineralogical analyses of weathered rocks combined with the dating of clay mineral illite.”
During the worst of the hothouse conditions, life in Earth’s oceans was untenable. There was little to no oxygen. But chemical weathering created new minerals which worked to trap CO2. As carbon dioxide was pulled out of the atmosphere, Earth slowly became more hospitable to life.
“Transport of loose material towards the ocean may have stimulated both end of life through formation of oxygen-depleted waters as well as recovery of life through stabilization of the greenhouse effect through CO2 removal,” Knies said.
