While a number of theories have been put forward to explain this landmark period, the most credible is that it was fuelled by a significant rise in oxygen levels which allowed a wide variety of animals to thrive.
The new study suggests that such a rise in oxygen levels was the result of extraordinary changes in global plate tectonics.
During the formation of the supercontinent ‘Gondwana’, there was a major increase in continental arc volcanism — chains of volcanoes often thousands of miles long formed where continental and oceanic tectonic plates collided. This in turn led to increased ‘degassing’ of CO2 from ancient, subducted sedimentary rocks.
This, the team calculated, led to an increase in atmospheric CO2 and warming of the planet, which in turn amplified the weathering of continental rocks, which supplied the nutrient phosphorus to the ocean to drive photosynthesis and oxygen production…
Williams added: “What is particularly compelling about this research is that not only does the model predict a rise in oxygen to levels estimated to be necessary to support the large, mobile, predatory animal life of the Cambrian, but the model predictions also show strong agreement with existing geochemical evidence.”
“It is remarkable to think that our oldest animal ancestors — and therefore all of us — may owe our existence, in part, to an unusual episode of plate tectonics over half a billion years ago” said Professor Lenton. Paper. (open access) – Joshua J. Williams, Benjamin J. W. Mills, Timothy M. Lenton. A tectonically driven Ediacaran oxygenation event. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-10286-x More.
Note: “It is remarkable to think that our oldest animal ancestors — and therefore all of us — may owe our existence, in part, to an unusual episode of plate tectonics over half a billion years ago” Is this a philosophical statement of some kind?
There is a rich vein of causes of the Cambrian explosion. Here is a handful:
Extreme fluctuation in oxygen levels
Cambrian animals remade the environment by generating oxygen
Did a low oxygen level delay complex life on Earth?
There was only a small oxygen jump
Animals didn’t “arise” from oxygenation, they created it, researchers say
Theory on how animals evolved challenged: Some need almost no oxygen
New study: Oxygenic photosynthesis goes back three billion years
Enough O2 long before animals?
Life exploded after slow O2 rise?
So the Cambrian really WAS an explosion then?
Researchers: Cambrian explosion was not an explosion after all (When in doubt, insist that nothing happened.)
oh, and The Great Unconformity.