Tetrahedrally coordinated carbonates in Earth's lower mantle.

  title={Tetrahedrally coordinated carbonates in Earth's lower mantle.},
  author={E. Boulard and Ding Pan and Giulia Galli and Zhenxian Liu and Wendy L. Mao},
  journal={Nature communications},
Carbonates are the main species that bring carbon deep into our planet through subduction. They are an important rock-forming mineral group, fundamentally distinct from silicates in the Earth's crust in that carbon binds to three oxygen atoms, while silicon is bonded to four oxygens. Here we present experimental evidence that under the sufficiently high pressures and high temperatures existing in the lower mantle, ferromagnesian carbonates transform to a phase with tetrahedrally coordinated… 
Fate of Carbonates in the Earth’s Mantle (10-136 GPa)
Earth carbon cycle shapes the evolution of our planet and our habitats. As a key region of carbon cycle, subduction zone acts as a sole channel transporting supracrustal carbonate rocks down to the
Stability of iron-bearing carbonates in the deep Earth’s interior
Fe4C4O13 is stable at conditions along the entire geotherm to depths of at least 2,500 km, thus demonstrating that self-oxidation-reduction reactions can preserve carbonates in the Earth’s lower mantle.
A novel carbon bonding environment in deep mantle high-pressure dolomite
Abstract The main source of carbon entering the deep Earth is through subduction of carbonates, including CaMg(CO3)2-dolomite. We examine the high-pressure structure and stability of dolomite to
The Speciation and Coordination of a Deep Earth Carbonate‐Silicate‐Metal Melt
Ab initio molecular dynamics calculations on a carbonate‐silicate‐metal melt were performed to study speciation and coordination changes as a function of pressure and temperature. We examine in
Transformations and Decomposition of MnCO3 at Earth's Lower Mantle Conditions
Carbonates have been proposed as the principal oxidized carbon-bearing phases in the Earth’s interior. Their phase diagram for the high pressure and temperature conditions of the mantle can provide
Crystal Structure Evolution of CaSiO3 Polymorphs at Earth’s Mantle Pressures
CaSiO3 polymorphs are abundant in only unique geological settings on the Earth’s surface and are the major Ca-bearing phases at deep mantle condition. An accurate and comprehensive study of their
High‐Pressure Transformations and Stability of Ferromagnesite in the Earth's Mantle
Ferromagnesite (Mg,Fe)CO3 plays a key role in the transport and storage of carbon in the deep Earth. Experimental and theoretical studies demonstrated its high stability at high pressure and
CO3+1 network formation in ultra-high pressure carbonate liquids
This study shows the clear formation of extended low-dimensional carbonate networks of close CO3 2− pairs and the emergence of a “three plus one” local coordination environment, producing an unexpected increase in viscosity with pressure.
Tracing the Deep Carbon Cycle Using Metal Stable Isotopes: Opportunities and Challenges


New host for carbon in the deep Earth
The existence of a new Mg-Fe carbon-bearing compound at depths greater than 1,800 km is shown, based on three-membered rings of corner-sharing (CO4)4- tetrahedra, in close agreement with predictions by first principles quantum calculations.
Stability of magnesite and its high-pressure form in the lowermost mantle
It is found that magnesite transforms to an unknown form at pressures above ∼115 GPa and temperatures of 2,100–2,200 K (depths of ∼2,600 km) without any dissociation, suggesting that Magnesite and its high-pressure form may be the major hosts for carbon throughout most parts of the Earth's lower mantle.
Experimental investigation of the stability of Fe‐rich carbonates in the lower mantle
The fate of carbonates in the Earth's mantle plays a key role in the geodynamical carbon cycle. Although iron is a major component of the Earth's lower mantle, the stability of Fe-bearing carbonates
Carbonate Melts and Carbonatites
Carbonatites are familiar to students of petrology as rare igneous rocks formed predominantly of carbonate, whose only modern expression is a single active volcano that erupts strongly alkaline
Bonding and structural changes in siderite at high pressure
Abstract Understanding the physical and chemical properties of carbonate minerals at extreme conditions is important for modeling the deep carbon cycle, because they represent likely hosts for carbon
Water and carbon in the Earth´s mantle
  • B. Wood, A. Pawley, D. Frost
  • Geology
    Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences
  • 1996
The concentrations of H2O and C in mid-ocean ridge basalts indicate that the upper, degassed, part of the mantle contains approximately 200 ppm H2O and 80 ppm C. Estimates for the bulk silicate earth
Ultralow viscosity of carbonate melts at high pressures.
Knowledge of the occurrence and mobility of carbonate-rich melts in the Earth's mantle is important for understanding the deep carbon cycle and related geochemical and geophysical processes. However,
Siderite at lower mantle conditions and the effects of the pressure‐induced spin‐pairing transition
Siderite (FeCO3) forms a complete solid solution with magnesite (MgCO3), the most likely candidate for a mantle carbonate. Our experiments with natural siderite reveal spin pairing of d‐orbital
Partially collapsed cristobalite structure in the non molecular phase V in CO2
CO2-V obtained from molecular CO2 at 40–50 GPa and T > 1500 K is investigated using synchrotron X-ray diffraction, optical spectroscopy, and computer simulations to confirm the existence of CO4 tetrahedra and add to the knowledge of carbon chemistry with mineral phases similar to SiO2.