Send to

Choose Destination
Sci Adv. 2017 Sep 13;3(9):e1701338. doi: 10.1126/sciadv.1701338. eCollection 2017 Sep.

Size effects resolve discrepancies in 40 years of work on low-temperature plasticity in olivine.

Author information

Department of Geological Sciences, Stanford University, Stanford, CA 94305, USA.
Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
Department of Earth Science, University of Oxford, Oxford, UK.
Department of Materials, University of Oxford, Oxford, UK.
Department of Geological Sciences, University of Delaware, Newark, DE 19716, USA.


The strength of olivine at low temperatures and high stresses in Earth's lithospheric mantle exerts a critical control on many geodynamic processes, including lithospheric flexure and the formation of plate boundaries. Unfortunately, laboratory-derived values of the strength of olivine at lithospheric conditions are highly variable and significantly disagree with those inferred from geophysical observations. We demonstrate via nanoindentation that the strength of olivine depends on the length scale of deformation, with experiments on smaller volumes of material exhibiting larger yield stresses. This "size effect" resolves discrepancies among previous measurements of olivine strength using other techniques. It also corroborates the most recent flow law for olivine, which proposes a much weaker lithospheric mantle than previously estimated, thus bringing experimental measurements into closer alignment with geophysical constraints. Further implications include an increased difficulty of activating plasticity in cold, fine-grained shear zones and an impact on the evolution of fault surface roughness due to the size-dependent deformation of nanometer- to micrometer-sized asperities.

Supplemental Content

Full text links

Icon for PubMed Central
Loading ...
Support Center