An Overview
Program: RESESS Boulder
Major: Physics
Academic Affiliation: Drama and Mathematics
Biography
Benjamin Miller (he/him) is a recent graduate of Tufts University, where he received a B.S in Physics with a Minor in Mathematics. As a member of the 2020 RESESS Cohort, Ben is overjoyed to be returning to the program, this time working with Fiske Planetarium and the American Museum of Natural History on producing visualization assets for NASA SciAct’s Science Through Shadows grant. Specifically, he will be developing assets based on the topics of stellar occultation and lunar eclipses in the OpenSpace planetarium platform. He is incredibly excited to begin his professional career and looks forward to engaging with space science and the wonderful mentors at RESESS throughout the summer.
Abstract
Geochemical consequences of Pressure and Temperature in arc magma formation: Modeled partitioning of Sr/Y and La/Yb in primary arc magmas.
‘Pseudobarometers’ are a methodology for the reconstruction of ancient arc crustal thickness in continental collision zones. Making use of recently observed empirical correlations between the depth of the Mohorovičić discontinuity and Sr/Y and La/Yb ratios, ‘pseudobarometers’ have risen in popularity among geochemists due to their relatively simple application compared to thermobarometers, a reliable but complex way to estimate crustal thickness. However, when compared to natural data from sampled sites spread across the world, there is significant deviance found between the crustal thickness values generated from Sr/Y and La/Yb ratios and the actual values experimentally observed for the same samples. Factors aside from Moho depth must impact the trace element ratios of surface arc magmas, negatively affecting the reliability of ‘pseudobarometers’. Therefore, in this study, we investigate the initial conditions at which arc magmas form and their impact on post-melt trace element composition. We use ideal solid solution models and a standardized bulk composition to simulate the evolution of a general arc magma and to isolate the effect of formation depth on Sr/Y and La/Yb ratios. The trace element ratios gathered through this model were substantially lower than those from the natural data, indicating that while there is a positive correlation between Moho depth and both Sr/Y and La/Yb, alternate factors have a significant impact on these ratios. From this data, we can better identify areas of research that are necessary for reliable application of ‘pseudobarometers’ as proxies for crustal thickness reconstruction.