Mantle Flow Explains Grand Canyon's 1.2 Billion-Year Rock Gap

3 articles · Updated · Livescience.com · Nov 11

A new Nature study ties the Grand Canyon's Great Unconformity to deep mantle circulation, saying uplift exposed rocks to erosion and erased about 1.2 billion years from the local record.
The model points to North America, the Baltics and northern China, where heat-driven mantle motion first raised continents during the Neoproterozoic and later let them sink, allowing sediment layers to accumulate again.
That two-step pattern matches the sharp contact between 1.7 billion-year-old basement rocks and roughly 500 million-year-old sedimentary layers seen in the canyon and other regions.
Researchers say glaciation such as Snowball Earth may still have helped strip sediment, but argue mantle-driven uplift created the slopes needed for erosion on a continental scale.
Geologists say the process may also have shaped conditions before the Cambrian explosion by altering sediment, nutrient and atmospheric cycles linked to the rise of complex life.