Welcome Garrett!

Welcome new Ph.D. student, Garrett Diedrich (B.S. University of Minnesota), starting at MSU Fall 2018! We also say goodbye and great job to our summer REU student, Olivia Krieger, who is heading back to Allegheny College to finish her bachelor’s degree in physics.

Valence and spin states of iron are invisible in Earth’s lower mantle

Our new article, “Valence and spin states of iron are invisible in Earth’s lower mantle,” is now published in Nature Communications! The project, led by postdoc Jiachao Liu, answers the question, “can we use geophysical measurements to map the composition of Earth’s mantle?” This is the first publication to come out of work initiated with MSU funding, and also our first in a Nature-family journal!

Press release related to this publication:

Mantle minerals offer clues to deep Earth’s composition – MSU News

CAREER!!

It’s official! We’re celebrating our new grant to sole PI Susannah Dorfman, “CAREER: Experimental Constraints on Carbon-Iron Redox Interaction in Earth’s Deep Lower Mantle,” awarded by NSF (EAR-1751664)!

carbon redox overview

Public abstract:

Earth’s deep carbon cycle affects the past, present and future of life on our planet. Carbon chemistry at depth is responsible for carbon sequestration and volcanism. The growth of diamonds at depth not only drives an industry, but also traps and preserves our only samples of Earth’s deep interior. Earth’s lower mantle, the Earth’s biggest layer, has great capacity for carbon even at very low concentrations and is thus important to the global carbon budget. The project will integrate research in the role of the mantle in Earth’s deep carbon cycle with an education plan that includes recruitment of diverse students to laboratory geoscience and improves teaching of spatial reasoning, a critical skill for Earth scientists, at Michigan State University (MSU) and beyond. The whole-Earth carbon cycle is a timely subject well-suited to outreach to attract students with interest in environmental problems to careers in geosciences. Short modules on carbon mineralogy and geochemistry will be developed for gateway courses in geology and global change at MSU. The effectiveness of these exercises will be assessed in terms of recruitment of undergraduate majors and developing spatial reasoning skills for geoscience careers. Undergraduate and graduate research assistants will participate both in the lab and in geoscience teaching evaluation.

The primary research goal is to determine the stability of carbon-bearing phases in petrologic context at conditions of the lower mantle. Depth- and region-dependent differences in mantle mineralogy and oxygen fugacity (fO2) will result in changes in the speciation and host phases of carbon within the mantle phase assemblage. Quantifying the relationship between stability of carbon-bearing phases and pressure, temperature, redox conditions, and major mineralogy is critical to understanding the fate of carbon in Earth’s interior. Experiments performed in laser-heated diamond anvil cells will provide some of the first experimental constraints on carbonate and carbide stability and physical properties in petrologic context of mantle phase assemblages at pressure-temperature conditions reaching the Core-Mantle Boundary (CMB). The results of the proposed experiments will be necessary to an integrated understanding of the origin, storage, and flux of carbon among a community including geochemists, cosmochemists, volcanologists, petrologists, mineralogists, and geophysicists. Earth’s carbon cycle and popular interest in diamonds offer an opportunity to teach and recruit students through coursework and research assistantships. The education component of this project is a collaboration between the PI and geocognition expert Dr. Julie Libarkin to develop and evaluate educational modules incorporating deep carbon context and developing 3D reasoning skills. Modules will be evaluated by in-class observations, surveys and interviews and disseminated openly online.

https://www.nsf.gov/awardsearch/showAward?AWD_ID=1751664

Diamonds and marbles at the core-mantle boundary

Our new paper, “Carbonate stability in the reduced lower mantle,” is now live at Earth and Planetary Science Letters and will be printed in the May 1st issue! This work, conducted mostly at EPFL with a fellowship from the Swiss National Science Foundation, examines the effects of redox conditions, pressure and temperature on the breakdown of carbonates and formation of diamonds in Earth’s lower mantle. We use transmission electron microscopy on samples recovered from the laser-heated diamond anvil cell to show that metallic iron promotes breakdown of MgCO3 but that CaCO3 is preserved in contact with diamonds at conditions near those at the core-mantle boundary. Thanks to coauthors James Badro, Farhang Nabiei, Vitali Prakapenka, Marco Cantoni and Philippe Gillet!

Until April 27th, the article is openly available for free at this link!

AGU 2017

Congratulations to Ph.D. student Mingda Lv and postdoc alum Jiachao Liu on their contributed oral presentations at AGU in New Orleans. Good job also to Ph.D. candidate Ben Brugman on his first AGU poster!

Lv, M., S. M. Dorfman, J. Liu, A. B. Farmer, V. Potapkin, A. I. Chumakov, C. A. McCammon, V. B. Prakapenka, D. Popov, “Experimental insights into spin state and hyperfine parameters of Fe3+ in bridgmanite and silicate glass up to 91 GPa,” American Geophysical Union Fall Meeting, New Orleans, LA, 2017.

Liu, J., S. M. Dorfman, M. Lv, J. Li and Y. Kono, “Release of Nitrogen during Planetary Accretion Explains Missing Nitrogen in Earth’s Mantle,” American Geophysical Union Fall Meeting, New Orleans, LA, 2017.

Brugman, B. L., M. Lv, J. Liu, C. Park, D. Popov, V. B. Prakapenka, and S. M. Dorfman, “Strength and Deformation of Solid Krypton and Xenon to Mbar Pressures,” American Geophysical Union Fall Meeting, New Orleans, LA, 2017.