COG3 Seminar: Rebecca Fisher (Harvard)
Earth's Accretion, Core Formation, and Core Composition
The Earth accreted in a series of increasingly large and violent impacts, which caused large-scale melting of its mantle. This allowed the core to segregate from the mantle during accretion, undergoing high pressure (P), high temperature (T) metal–silicate partitioning reactions that set the modern-day compositions of the core and mantle. This talk presents a series of interconnected projects that describe these processes and their effects on core composition. Equations of state of iron-rich materials are compared to the seismologically-determined density of the core to constrain its light element abundance, high P-T metal–silicate partitioning experiments are used to study the behavior of Ni, Co, V, Cr, Si, and O during core formation, and a suite of 100 N-body simulations are presented to show a probabilistic assessment of terrestrial planet accretion. From these studies, a chemical model of core formation is built that allows calculation of Earth’s core composition as it formed, based on the growth history provided by the accretion simulations and the measured partitioning behavior.
About the Speaker:
Rebecca A. Fischer is the Clare Boothe Luce Assistant Professor of Earth and Planetary Sciences in the Department of Earth and Planetary Sciences at Harvard University. She lists her interests as: "Accretion, core formation, and composition of the deep interiors of Earth and other terrestrial planets." Her research combines high-pressure, high-temperature mineral physics experiments with planetary-scale modeling.
Fischer received a BA in Earth and Planetary Sciences and Integrated Science from Northwestern University in 2009, and a PhD in Geophysical Sciences from the University of Chicago in 2015.
About this Series:
The Chemical Oceanography, Geology, Geochemistry, and Geobiology Seminar [COG3] is a student-run seminar series. Topics include chemical oceanography, geology, geochemistry, and geobiology. The seminars take place on Fridays from 10-11am in Building E25, Room 119, unless otherwise noted (term-time only).