Melissa Sims

Graduate Student, Stony Brook University

Geosciences

Specialty: Mineral Physics

AGEP-T FRAME Research Mentor: Dr. Lars Ehm                                                                          

Email: Melissa.Sims@stonybrook.edu 

I'm originally from South Carolina, where I received bachelors' degrees in astronomy and geophysics from the College of Charleston and University of South Carolina, respectively. I came to Stony Brook to earn a Master's degree in geosciences and decided to stay for the PhD program.

Seminar Title: Insights into Shocked Feldspar Systems from Adventures in Rate-Dependent in-situ Compression and Heating Experiments.

Description: Plagioclase is a framework silicate mineral commonly found within the Earth's crust. It can be used as an important method to trace the composition and histories of igneous rocks. The phase of plagioclase is a fundamental metric used in impact (shock) metamorphism to ascertain what pressure-temperature conditions occurred in impact sites. Shock processes also would have played an important role in the early solar system, such as during the accretionary period and during late bombardment, as well as for meteorites ejected from Mars.

The high-pressure phase diagram for plagioclase compositions is ambiguous. This is because there are three methods used to study impact metamorphism. These experiments produce conflicting results due to kinetic differences between the shock, static DAC, and multi-anvil experiments that are caused by differing timescales and uniformity of pressure applied. We conduct rapid compression time-resolved X-ray diffraction experiments in order to reinvestigate the phase diagram of plagioclase as a function of strain and strain rate in order to reach those close to natural impacts. With these findings, impact-genesis studies can better constrain and apply phase transitions to determine impact conditions.

Publications:

Dukes, R.J., Bramlett, J. and Sims, M., (2009). Comparison of Frequency Determinations of Slowly Pulsating B Stars from Stromgren and Geneva Data, Stellar Pulsation: Challenges for Theory and Observation: Proceedings of the International Conference. American Institute of Physics Conference Proceedings, vol. 1170, p. 379-381.

Dukes, R.J., Mills, L. and Sims, M., (2008). Slowly Pulsating B Stars: A Challenge for Photometrists, The Journal of the American Association of Variable Star Observers, vol. 36, no. 1, p. 141-142.

Wu, X., Monti, A., and Sims, M., (2003). A Tool for Automatic Identification and Validation of Simulation Models (Conference paper). Proc. of Huntsville Simulation Conference, Huntsville, AL, USA, October