Mineral Physicist Jennifer Jackson: Investigating Earth’s Interior with Diamonds, X-rays, and Lasers

Mineral Physicist Jennifer Jackson: Investigating Earth’s Interior with Diamonds, X-rays, and Lasers

I’m Jennifer Jackson. I’m a professor of
mineral physics in the Seismological Laboratory at Caltech. Mineral physics
involves understanding the atomic level properties of solids, liquids as they
pertain to earth and planetary interiors. The Seismo Lab is a group of scientists
that are interested in understanding how the earth works and that necessarily
involves understanding the interior of the planet. One of these structures that
I really want to understand is something called an Ultralow Velocity Zone. There
are actually many of these on the base of the mantle that are covering the core
mantle boundary surface, and these little patches slow down seismic waves by 10 to up to 50 percent. And it’s still not clear what
they’re made of, why they are there. And this is something that I’m really
passionate about understanding because it can ultimately connect the whole
formation of the earth. This is what is really exciting for me is to understand
the landscape at the core-mantle boundary and understand what’s
responsible for it. So we have a good understanding about what the shallow
portions of the earth are made of. We can look at these geologic structures and
infer that some of them have signatures of the earth’s mantle. And we can then
take these rocks and look at their mineral assemblages. We can see that
there are some minerals that are representative of the deeper parts of
the mantle. We can then take those minerals and push them further into the
earth using what are called diamond anvil cells. They involve using two
diamonds and the minerals are placed in between these anvils that allows us to place a small amount of force on an even smaller area and
this can then generate millions of times the pressure that we feel at the earth’s
surface. And these are the pressures that these minerals are experiencing inside
of the earth. These samples that we have to load into the cells are the size of a
human hair. We squeeze them in between the two anvils and we also take them to
Argonne National Laboratory. There’s a very brilliant source of x-rays there.
This brilliant source of x-rays allows us to probe the minerals under their
high pressures and high temperature conditions and essentially the diamond
anvils act as windows. And so the x-rays can penetrate through the diamond anvils
and we can place detectors on the other side of the cell and measure properties
like compressional wave velocity or the shear wave velocity. It’s hard to put my
finger on favorite aspect of what I do because it is all really exciting for me,
from the training students and postdocs in the lab, to conducting the experiments,
to discussing them with my colleagues, and trying to figure out
what makes the earth tick.

One thought on “Mineral Physicist Jennifer Jackson: Investigating Earth’s Interior with Diamonds, X-rays, and Lasers

  1. Professor Jackson, thank you for telling us a little about your work. Do the ‘states of matter’ like water (ice, & steam) apply to rocks under the earth? What I mean is, are minerals either a solid or a liquid or is there a continuous change in properties between the two? I just reread my question and I’m not sure I’m being clear. Forgive an old Biologist, I never took a Geology course.

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