The unusual capability of solid crystalline materials to deform plastically (known as superplasticity) has been found in metals and even ceramics; however, no experimental studies have yet to demonstrate this behaviour in geological materials. It is now demonstrated that some synthetic rocks, which are good analogues for Earth's mantle, undergo homogeneous elongation up to 500% under subsolidus conditions. Calculations show that such superplastic flow in the mantle is inevitably accompanied by significant grain growth that can change fine-grained rocks to coarse-grained aggregates, resulting in increasing mantle viscosity and finally termination of superplastic flow.
- Takehiko Hiraga
- Tomonori Miyazaki
- Hidehiro Yoshida
