Mars is an ideal planet to study planetary evolution and development, as its crust has been preserved over its history, rather than continuously recycled through subduction, as has happened on Earth. In order to attain a more coherent understanding of martian evolution, we focused on the thermal and petrologic history of the martian lithosphere. We developed a model that calculates the thermal state and melt composition of Mars over time. This model provides insight into the planet's history and enables us to describe how the density and seismic properties have evolved over time. We calculated the temperature profile through the lithosphere and then fit an equation to pre-existing experimental data in order to produce a model to predict the composition of melt produced as a function of pressure and temperature. From the melt model, we see a trend from ultramafic to mafic composition over time. We calculated the density and seismic properties of the lithosphere and found that they increase over time, but decrease with depth, which is consistent with the recent observations of NASA's InSight mission. / Master of Science / Mars is an excellent location to study how planets change over time because its crust has remained intact, rather than being destroyed as segments of the crust move and push against each other, which happens on Earth. In order to understand how Mars has evolved over time, we built a model to show how the top part of the planet has changed over time. The model works by calculating the temperature of the rocks. We calculated these temperatures in the present day and at four, three, two, and one billion years ago. We took the temperatures and used them to calculate the elements that are present in the rocks. Knowing the chemistry of the crust made it possible for us to calculate the minerals present in the crust and upper mantle, which we used to calculate the density of the outer layers of Mars and the speed at which earthquake waves would travel through the layers. We found that the density and earthquake wave speeds decrease over the depth of the top part of the planet. Although usually an object that is denser at the top than bottom will flip over, we believe this will not happen on Mars because the rocks are thick enough to prevent them from flipping.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/106658 |
| Date | 16 November 2021 |
| Creators | McGroarty, Fiona Clare |
| Contributors | Geosciences, Duncan, Megan S., Ross, Nancy L., Caddick, Mark J., King, Scott D. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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