Overview
- A Nature study published Friday used six mantle-convection runs to test the idea that slow mantle flow pushed continents up and later let them sink, producing conditions for the missing rock layers.
- The models most consistently show Laurentia (ancient North America) rose from about 930 million to 510 million years ago and then subsided in the Cambrian, a pattern seen in five of six simulations.
- The authors say uplift alone was too weak to remove thick rock, but when Neoproterozoic glaciations ground over already elevated continents, the intense erosion could produce the unconformity and later be buried as the land sank.
- Simulations required heavy computing on the Gadi supercomputer and match why the unconformity is clear in places like the Grand Canyon yet patchy on other continents, but the results depend on uncertain starting maps, continent longitudes, and reconstructions of lost ocean crust.
- The team notes that huge erosion could have dumped nutrients and calcium into the oceans before the Cambrian explosion but cautions that this chemical link is plausible rather than proven and is only one of several interacting factors.