How can lava/magma transport information?

Question

Not a test question, just something a friend asked me and I didn't know.

I am guessing it has something to do with composite and shield volcanoes and that they erupt lava at different temperatures.

Can anybody go a but further? Thank you :-)

Answer 1

I think he was referring to xenoliths. Xenoliths, Latin for foreign, are rocks brought up from depth during volcanic eruptions. Some are bits of the Earth's mantle come from 370 miles deep. They are valuable in telling us the composition and conditions of the deep interior of the Earth, as we cannot drill so deep (25 km at most).

Some xenoliths are sent to laboratories where they are subjected to the same temperature and pressures that exist in the real mantle, in a laboratory device called a Diamond Anvil Cell. The mineral changes observed under a microscope reveal what the real Earth's mantle is really like.

The Diamond Anvil Cell is a fascinating laboratory instrument that was devloped in the 1950s by 4 scientists working in the NSB labs in Washington. The mineral sample is squashed and heated between two diamonds (the hardest substance known), up to pressures of 1 million atmospheres.