It is not an easy subject to learn without foundation, and it looks like you may be confusing a few different subjects. We know quite a bit about the composition of the mantle. We can't drill to those depths, but it finds its way up (see: mantle xenoliths, ophiolites). Determining parentage and provenance of a magma body through chemistry is one of many applications of igneous petrology.
If you would like references on mantle dynamics/geochemistry, please DM, I am happy to share.
MindlessCollar842 t1_je5as5e wrote
Reply to comment by dat_lpn_lifetho in Around 550 million years ago the earth's magnetic field almost collapsed, but then strengthened a few million years later. Scientists say this may have been due to the formation of the inner core. But why exactly would that cause the magnetic field to get stronger? by somethingX
It is not an easy subject to learn without foundation, and it looks like you may be confusing a few different subjects. We know quite a bit about the composition of the mantle. We can't drill to those depths, but it finds its way up (see: mantle xenoliths, ophiolites). Determining parentage and provenance of a magma body through chemistry is one of many applications of igneous petrology. If you would like references on mantle dynamics/geochemistry, please DM, I am happy to share.