UD researchers had a hand in a new study offering insight into the thickness of the earth's plates.
Scientists have known for decades that the top of a plate tectonic is the surface of the Earth. But because the bottom of the plate is difficult to measure, scientists have had trouble agreeing on how thick plates actually are.
"Everything inside the earth is driving what we seeing at the surface, so all of the Plate tectonics processes that’s driving earthquakes and volcanoes - we need to see inside the earth to understand it," said the University of Delaware’s Jessica Warren.
Warren and her colleagues added melt to a mineral called olivine to mimic how a plate is created at a mid-ocean ridge. They then twisted it under high temperatures and pressures to show how olivine behaves inside the Earth and how melt influences the mineral’s behavior.
And using a theory on temperature change, they determined plate tectonics are about 75 miles thick.
Warren says knowing that helps scientists create better models of the Earth.
"I like the ability to take this theory that we have and go out and look at mountains and understand why it is we get volcanoes, why it is that we get earthquakes," said Warren."The people that try to model how the plates move around on the surface of the earth and how they collide and how some go back down into the earth and subduction zones or how they push up mountains in the Himalayas today. If you don’t know the thickness of the plate you’re dealing with your models are very unconstrained."
Warren adds there’s 30 to 40 years of prior research on olivine and plate tectonics, but this is one of only a few experiments adding melt into the olivine - changing the crystals’ properties.
The team plans to continue experimenting with olivine and how its form changes inside the Earth.
Journal reference: Lars N. Hansen, Chao Qi & Jessica M. Warren. Olivine anisotropy suggests Gutenberg discontinuity is not the base of the lithosphere. Proceedings of the National Academy of Sciences, 2016; 113, 38.10503–10506, DOI: 10.1073/pnas.1608269113