Natural, Experimental, and Educational Explorations of the Interiors of Terrestrial Planetary Bodies

Planetary interiors are enigmatic, inaccessible, and vital to the processes that have formed the rocks we see on the surface of bodies in the inner Solar System today. Based on geophysical explorations of the Moon and Earth, along with information gleaned from rocks at the surface today, there is understanding of the basic structure and processes at depth. Using a combination of natural samples and experimental studies, we attempt to learn more about the physical conditions beneath the surface, and their effect on material properties and tectonics processes in the mantle.

On Earth, mid-ocean ridge processes have long been debated, and there has been little consensus on the magmatic plumbing and extent of ocean-water circulation at depth, leaving a debate between two end-member models of crustal accretion. Using geothermometry and geospedometry of lower-crustal and upper-mantle rocks from a paleo-ridge in the Samail Ophiolte, alongside a similar suite of rocks from the actively spreading East Pacific Rise at Hess Deep, we compare the thermal structure of the crust-mantle transition zone and implications for the on-axis processes that form much of the Earth’s crust.

Past work has constrained the crystallization sequence of the moon through time and determined one of the last layers to crystallize was highly dense, containing a significant fraction of the mineral ilmenite, and initially formed above the less-dense mantle cumulate pile, composed mainly of mafic minerals. To study the possible interactions of these two layers due to the density instability, I completed shear deformation experiments on ilmenite and olivine aggregates, in equilibrium, to compare to aggregate flow laws proposed for phase mixing and determine the system rheology.

To introduce high school students in East Tennessee to the concept of mantle materials and conditions versus crustal materials and their formation conditions, I have created an activity and corresponding lesson plan for use in secondary school Chemistry classrooms. This activity combines phase diagrams, physical models of chemical bonds, and a comparison of two native minerals with the same chemical formula to help students think about the effects of pressure and temperature on Earth materials.