An Inside Look at Carbon in Earth’s Interior

A decade of DCO research from the Extreme Physics and Chemistry community is synthesized in an American Geophysical Union Monograph entitled Carbon in Earth’s Interior, to be published in December 2019.

AGU Monograph coverMore than 50 DCO scientists contributed to a special American Geophysical Union (AGU) Monograph, Carbon in Earth’s Interior. The book brings together research from mineral physics, materials science, petrology, and geochemistry. Chapters feature new work on the behavior of carbon in minerals, fluids, and melted rocks under the extreme conditions that occur within Earth’s interior. The co-chairs of the Extreme Physics and Chemistry community, Craig Manning (University of California, Los Angeles, USA) and Wendy Mao (Stanford University, USA), along with Jung-Fu Lin (University of Texas, USA) edited the monograph. The book will be available in December 2019.

“This monograph represents the decadal effort of the community in revealing the physical and chemical properties of deep carbon,” said Lin.

The editors approached AGU with the idea for the monograph because many Extreme Physics and Chemistry community members belong to the organization, and in the past, their monographs have synthesized multidisciplinary work on complex topics. “It’s a mixture of reviews and new results,” said Manning. “It nicely spans all of the subject areas that we’ve been focusing on in the Extreme Physics and Chemistry community, so it’s thematically complete and the quality of the papers is quite high.” 

Articles in the monograph highlight discoveries made in the last 10 years in understanding carbon chemistry and physics at extreme conditions. The monograph documents significant advances in understanding how carbon and oxygen interact and the forms they take at high pressures. At surface pressure, carbon dioxide forms an ice, much like water ice. But at elevated pressures, carbon dioxide transitions into a structure where the carbon bonds to more oxygen atoms, interlinking to form a polymer. This polymerization also occurs in carbonate minerals in deep Earth. The extreme pressure in the deep mantle changes how oxidized carbon is and also energizes carbon to substitute into silicate structures.

Some chapters focus on how carbon dioxide interacts with other components in molten rock such as water, which will affect the movement of carbon in the subsurface. Organic compounds at extreme conditions also are a focus. “The way that carbon, hydrogen and water interact is a really important problem and it will govern all of the chemistry of this form of carbon at planetary interiors,” said Manning. “I think ongoing interest in organic chemistry at high temperature and pressure will be a legacy of DCO.” 
The monograph also showcases advances in computer simulations that enable scientists to model planetary interiors with high resolution. The editors expect that this will be an active area of research for years to come.

“Understanding how carbon behaves at extreme conditions is such a rich topic that intersects many disciplines. This monograph demonstrates that even though much has been learned, we have still only barely scratched the surface in terms of understanding carbon in planetary interiors,” said Mao.


Table of contents:

Chapter 1 Pressure-induced sp2-sp3 transitions in carbon-bearing phases Lobanov SS, Goncharov AF
Chapter 2 High-pressure carbonaceous phases as minerals Tschauner O
Chapter 3 Phase and Melting Relations of Fe3C to 300 GPa and Carbon in the Core Takahashi S, Ohtani E, Sakai T, Kamada S, Ozawa S, Sakamaki T,
Miyahara M, Ito Y, Hirao N, Ohishi Y
Chapter 4 Structure and Properties of Liquid Fe-C Alloys at High Pressures by Experiments and First-Principles Calculations Chen B, Wang J
Chapter 5 A geologic Si-O-C pathway to incorporate carbon in silicates Navrotsky A, Percival J, Dobrzhinetskaya L
Chapter 6 Structural and chemical modifications of carbon dioxide in the deep Earth Santoro M, Gorelli F, Scelta D, Dziubek K, Bini R
Chapter 7 Carbon redox chemistry: Deep carbon dioxide and carbonates Yoo CS
Chapter 8 Crystallization of water mediated by carbon Li T, Bi YF, Cao B
Chapter 9 Structures and crystal chemistry of carbonate at Earth's mantle conditions Merlini M, Milani S, Maurice J
Chapter 11 High-pressure transformations and stability of ferromagnesite in the Earth’s mantle Boulard E, Guyot F, Fiquet G
Chapter 12 Spin transition of iron in deep-mantle ferromagnesite Liu J, Fu S, Lin J-F
Chapter 13 High-pressure Na-Ca carbonates in deep carbon cycle Rashchenko S, Shatskiy A, Litasov K
Chapter 14 Phase diagrams of carbonate materials at high-pressures, with implication to melting and carbon cycling in the deep Earth Litasov K, Shatskiy A, Podborodnikov I, Arefiev A
Chapter 15 Reactive preservation of carbonate in Earth’s mantle transition zone Li J, Zhu F, Liu J, Dong J
Chapter 16 Carbon speciation and solubility in silicate melts Solomatova N, Caracas R, Cohen R
Chapter 17 The effect of variable Na/K on the CO2 content of slab‐derived rhyolitic melts Muth M, Duncan M, Dasgupta R
Chapter 18 Hydrous carbonatitic liquids drive CO2 recycling from subducted marls and limestones Schettino E, Poli S
Chapter 19 The viscosity of carbonate-silicate transitional melts at Earth’s upper mantle pressures and temperatures, determined by the in situ falling-sphere technique Stagno V, Kono Y, Stopponi V, Masotta A, Scarlato P, Manning C
Chapter 20 Mixed fluids of water and carbon dioxide Abramson E
Chapter 21 Experimental determination of calcite solubility in H2O-KCl-NaCl-LiCl solutions at 700 °C and 8 kbar Eguchi J, Li Y, Manning C
Chapter 22 The changing character of aqueous and hydrocarbon fluids with pressure: Organic geochemistry of Earth’s upper mantle fluids Sverjensky D, Daniel I, Vitale Brovarone A
Chapter 23 Free energies of reaction for aqueous glycine condensation chemistry at extreme temperatures Kroonblawd MP, Goldman N
Chapter 24 Predicted speciation of carbon in subduction zone fluids Guild MR, Shock EL
Chapter 25 Energetics of the citric acid cycle in the deep biosphere Canovas PA, Shock E
Chapter 26 Deep hydrocarbon cycle: An experimental simulation Kutcherov V, Ivanov KS, Mukhina EM, Serovaiskii AY
Chapter 27 Diamondoids under pressure Park S, Lin Y, Mao WL

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