Deep Carbon: Past to Present

Cover
Half-title
Title page
Copyright information
Contents
List of Contributors
1 Introduction to Deep Carbon: Past to Present
Reference
2 Origin and Early Differentiation of Carbon and Associated Life-Essential Volatile Elements on Earth
2.1 Introduction
2.2 Constraints on the Compositions of Terrestrial Building Blocks
2.2.1 Constraints from Isotopes of Refractory Elements
2.2.2 Constraints from Isotopes of Highly Volatile Elements
2.2.3 Constraints from Theoretical Modeling
2.3 C and Other Volatiles: Abundances, Ratios, and Forms in Various Classes of Meteorites and Comparison with the BSE
2.4 Establishing LEVE Budgets of the BSE After Core Formation?
2.4.1 The Role of Late Accretion
2.4.2 The Role of Post-core Formation Sulfide Segregation
2.4.3 The Role of MO–Atmosphere Interactions and Atmospheric Loss
2.5 Establishing the Volatile Budget of the BSE through Equilibrium Accretion and MO Differentiation
2.5.1 Carbon Speciation in MO
2.5.2 Dalloy/silicateC and Its Impact on Carbon Distribution between BSE versus Core in Various Scenarios of Equilibrium Core Formation
2.5.3 Comparison of Dalloy/silicateC with Alloy–Silicate Melt Partitioning of Other LEVEs
2.6 C and Other LEVE Budgets of the BSE: A Memory of Multistage Accretion and Core Formation Process with Partial Equilibrium?
2.6.1 Disequilibrium Core Formation
2.7 Carbon as a Light Element in the Core
2.8 Conclusion
2.9 Limits of Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
3 Carbon versus Other Light Elements in Earth's Core
3.1 Introduction
3.2 Constraints on Carbon versus Other Light Elements in Earth's Core
3.2.1 Constraints from Phase Relations of Iron–Light Element Systems
3.2.2 Constraints from Densities of Fe–C Alloys and Compounds
3.2.2.1 Fe3C
3.2.2.2 Fe7C3
3.2.2.3 Fe–C Alloy Near the Iron End Member
3.2.2.4 Liquid Fe–C Alloy
3.2.2.5 Other Light Elements
3.2.3 Constraints from Sound Velocities of Fe–C Alloys and Compounds
3.2.3.1 Fe3C
3.2.3.2 Fe7C3
3.2.3.3 Fe–C Alloy Near the Iron End Member
3.2.3.4 Liquid Fe–C Alloy
3.2.3.5 Other Light Elements
3.2.4 Constraints from Melting Temperatures of Fe–C Alloys
3.3 Implications of Carbon as a Major Light Element in the Core
3.4 Carbon in the Core Over Time
3.5 Conclusion
3.6 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
4 Carbon-Bearing Phases throughout Earth's Interior: Evolution through Space and Time
4.1 Introduction
4.2 The Abundance, Speciation, and Extraction of Carbon from the Upper Mantle over Time
4.3 The Stability of Reduced and Oxidized Forms of Carbon in the Upper Mantle: Continental Lithosphere versus Convective Mantle
4.4 The Redox State and Speciation of C in the Transition Zone and Lower Mantle
4.4.1 Carbides and C in (Fe,Ni) Alloys
4.4.2 Carbonate Minerals in Earth's Interior
4.4.2.1 Dolomite and Its High-Pressure Polymorphs
4.4.2.2 Deep Carbon Stored as CaCO3-like Phases
4.4.2.3 Magnesite and Fe-Bearing Solid Solutions as Deep Carbon Reservoirs
4.4.3 Toward Oxy-Thermobarometry of the Deep Mantle and Implications for Carbon Speciation
4.5 Seismic Detectability of Reduced and Oxidized Carbon in Earth's Mantle
4.6 Conclusion
4.7 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
5 Diamonds and the Mantle Geodynamics of Carbon: Deep Mantle Carbon Evolution from the Diamond Record
5.1 Introduction
5.2 Physical Conditions of Diamond Formation
5.2.1 Measuring the Depth of Diamond Formation
5.2.2 Thermal Modeling of Diamond in the Mantle from Fourier-Transform Infrared Spectroscopy Maps
5.3 Diamond-Forming Reactions, Mechanisms, and Fluids
5.3.1 Direct Observation of Reduced Mantle Volatiles in Lithospheric and Sublithospheric Diamonds
5.3.2 Redox-Neutral Diamond Formation and Its Unexpected Effect on Carbon Isotope Fractionation
5.3.3 Progress in Understanding Diamond-Forming Metasomatic Fluids
5.4 Sources of Carbon and Recycling of Volatiles
5.4.1 Atmospheric and Biotic Recycling of Sulfur into the Mantle
5.4.2 Carbon and Nitrogen Cycling into the Mantle Transition Zone
5.4.3 Earth's Deep Water and the Carbon Cycle
5.5 Mineral Inclusions and Diamond Types
5.5.1 Experiments to Study Diamond Formation and Inclusion Entrapment
5.5.2 Nanoscale Evidence for Polycrystalline Diamond Formation
5.5.3 Proterozoic Lherzolitic Diamond Formation: A Deep and Early Precursor to Kimberlite Magmatism
5.5.4 Diamond Growth by Redox Freezing from Carbonated Melts in the Deep Mantle
5.5.5 Evidence for Carbon-Reducing Regions of the Convecting Mantle
5.6 Limits to Knowledge and Questions for the Future
Acknowledgments
References
6 CO2-Rich Melts in Earth
6.1 Introduction
6.2 Constraints on Carbonate Stability in Earth's Mantle
6.3 Experimental Constraints on the Melting of Carbonate Peridotite in the Mantle
6.4 Carbonate Melts Associated with Subduction Zones
6.5 Melting of Subducted, Carbonated Sediment and Ocean Crust in the Deep Upper Mantle and Transition Zone
6.6 Carbonate Melts and Kimberlites in the Cratonic Lithospheric Mantle
6.6.1 Kimberlites
6.6.2 Redox Constraints on Carbonate Stability in the Cratonic Lithospheric Mantle
6.6.3 The Involvement of Carbonate Melts in Metasomatism of the Deep Cratonic Lithospheric Mantle
6.7 Carbonate Melts beneath Ocean Islands in Intraplate Settings
6.7.1 How Do CO2-Rich Silicate Melts Form in the Upper Mantle? Can These CO2-Rich Melts Explain the Chemistry of Erupted Magmas in Intraplate Ocean Islands?
6.7.2 Effect of CO2 on the Reaction between Eclogite-Derived Partial Melts and Peridotite
6.8 Carbonate Melts under Mid-ocean Ridges
6.9 Crustally Emplaced Carbonatites
6.10 Concluding Remarks
6.11 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
7 The Link between the Physical and Chemical Properties of Carbon-Bearing Melts and Their Application for Geophysical Imaging of Earth's Mantle
7.1 Introduction: Toward a Geophysical Definition of Incipient Melting and Mantle Metasomatism
7.2 CO2-Rich Melts in the Mantle: Stability, Composition, and Structure
7.2.1 Partial Melting in the Presence of CO2 and H2O: Incipient Melting
7.2.2 Carbonate to Silicate Melts in Various Geodynamic Settings
7.2.3 Structural Differences between Silicate and Carbonate Melts
7.3 Physical Properties of CO2-Rich Melts in the Mantle
7.3.1 Evolution of the Melt Density with Composition, CO2, and H2O Contents
7.3.2 Transport Properties: Viscosity–Diffusion
7.3.3 Electrical Conductivity
7.4 Interconnection of CO2-Rich Melts in the Mantle
7.5 Mobility and Geophysical Imaging of Incipient Melts in the Upper Mantle
7.5.1 Melt Mobility as a Function of Melt Composition
7.5.2 EC versus Mobility of Incipient Melts
7.6 Conclusions
7.6.1 LAB versus Geophysical Discontinuities
7.6.2 Manifold Types of Mantle Convection Fuel Incipient Melting
7.7 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
8 Carbon Dioxide Emissions from Subaerial Volcanic Regions: Two Decades in Review
8.1 Introduction
8.2 Methods for Measuring Volcanic CO2: Established Techniques and Recent Advances
8.2.1 Measurements of CO2 Emissions in Volcanic Plumes
8.2.2 Diffuse CO2 Emissions and Groundwater Contributions
8.2.3 Significant Recent Advances: Continuous and Remote Techniques
8.3 Estimating Global Emission Rates of CO2
8.4 Current State of Knowledge of CO2 Degassing from Volcanoes
8.4.1 CO2 Emissions from Earth's Most Active Volcanoes
8.4.2 CO2 Emissions during Explosive Eruptions
8.4.3 CO2 Emissions from Dormant Volcanoes
8.4.3.1 Small Volcanic Plumes: Fumarolic Contributions
8.4.3.2 Diffuse Emission of CO2: Hydrothermal Systems, Calderas, and Continental Rifts
8.5 The Next Iteration of Global Volcanic CO2 Emissions
8.6 Temporal Variability of Volcanic Degassing
8.6.1 Comparison of the Temporal Variability of CO2 Emission from Active and Less Active Volcanoes
8.6.2 Using the Temporal Variability of CO2/SO2 in Volcanic Gas for Eruption Forecasting
8.7 Sources of Carbon Outgassed from Volcanoes
8.8 Volcanic Release of CO2 over Geologic Time
8.9 Synthesis
8.10 Limits to Knowledge of Volcanic Carbon
Acknowledgments
Questions for the Classroom
List of Online Resources
References
9 Carbon in the Convecting Mantle
9.1 Introduction
9.2 Sampling
9.3 Fluxes of CO2 from the Global Mid-Ocean Ridge System
9.3.1 MORB Melt Inclusions and the Usefulness of Volatile/Nonvolatile Element Ratios
9.3.2 Variations in Primary MORB CO2 Contents and CO2 Fluxes
9.4 Fluxes of CO2 from Mantle Plumes
9.5 Carbon Content of Convecting Mantle Sources
9.6 Carbon and Mantle Melting
9.7 Conclusions
9.8 Limits of Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
10 How Do Subduction Zones Regulate the Carbon Cycle?
10.1 Carbon Distribution on Earth
10.2 How Do Surface Processes Control the Subduction Carbon Cycle?
10.2.1 Sources to Sinks and Back
10.2.2 Heterogeneity of Sedimentary Carbonate Subduction (Carbonate Pump)
10.2.3 Hot Spot of Organic Carbon Subduction in the Sub-Arctic Pacific Rim (Soft Tissue Pump)
10.2.4 An Ancient Hydrothermal Carbon Sink
10.3 Is the Subduction Zone Carbon Neutral?
10.4 How Rocks Influence the Solubility of Carbon
10.4.1 Dissolution by Rising Pressure and Temperature: Which Silicate Is in Charge?
10.4.2 Carbonate Melts from Hot Slabs and Diapirs?
10.4.3 Where Is the Barrier to Deep Carbon Subduction?
10.4.4 Are Thermal Anomalies the Norm?
10.5 Transport and Reactivity of Carbon-Bearing Liquids
10.5.1 Pressure and Temperature
10.5.2 Low- and High-Temperature Redox Processes
10.5.3 SiO2 Activity
10.5.4 Water
10.6 Carbon Dynamics at the Subduction/Collision Transition
10.7 A Flavor of Life: A 3 Billion-Year-Old Record
10.7.1 Biological Evolution Influences Carbon Subduction: First Milestone
10.7.2 Biological Evolution Influences the Dioxygen Cycle: Second Milestone
10.7.3 Biological Evolution Influences the Cycle of Alkalinity: Third Milestone
10.7.4 Alkalinity Feeding Back into Biological Evolution: Fourth Milestone
10.7.5 Response of Climate to the Enhanced Subduction of Pelagic Carbonates
10.8 The Way Forward
10.9 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
Appendix to Chapter 10 How Do Subduction Zones Regulate the Carbon Cycle?
Supplementary Material: Description of the Model
References
11 A Framework for Understanding Whole-Earth Carbon Cycling
11.1 Introduction
11.2 Basic Concepts of Elemental Cycling
11.2.1 Steady State and Residence Time
11.2.2 Climatic Drivers versus Negative Feedbacks
11.2.3 When Systems Transition to New Steady States
11.3 Carbon Inventories of Earth Reservoirs
11.3.1 Modern and Primitive Mantle Reservoirs
11.3.2 Continental Crust and Continental Lithospheric Mantle
11.3.3 Exogenic Reservoirs
11.4 Long-Term Carbon Fluxes
11.4.1 Inputs
11.4.1.1 Volcanic Inputs
11.4.1.2 Metamorphic Inputs
11.4.1.3 Carbonate and Organic Carbon Weathering
11.4.1.4 Carbon Inputs Internal to the Exogenic System
11.4.2 Carbon Outputs
11.4.2.1 Silicate Weathering Chemistry and Carbonate Precipitation
11.4.2.2 Photosynthesis and Organic Carbon Burial
11.4.2.3 Subduction Flux
11.5 Efficiency of the Silicate Weathering Feedback
11.5.1 Seafloor Weathering Feedback
11.6 Discussion
11.6.1 Framework for Modeling Whole-Earth C Cycling
11.6.2 Is Earth's Mantle Degassing or ''Ingassing''?
11.6.3 What Drives Greenhouse and Icehouse Conditions?
11.6.3.1 Greenhouse Intervals
11.6.3.2 Icehouse Drivers
11.6.4 Climatic Excursions and Runaways
11.6.4.1 Hothouses
11.6.4.2 Snowballs
11.7 Summary and Further Research Directions
Acknowledgments
References
12 The Influence of Nanoporosity on the Behavior of Carbon-Bearing Fluids
12.1 Introduction
12.2 Nanopore Earth Materials and Fluids
12.2.1 Nanopore Features
12.2.2 Fluid Properties Affected by Nanoconfinement
12.3 Form and Movement: Transport Mechanisms under Nanoconfinement
12.3.1 Steric Effects Enhance Surface versus Pore Diffusion
12.3.2 Molecular Lubrication Enhances Pore Diffusion
12.3.3 Molecular Hurdles Due to Strong Fluid–Fluid Interactions
12.3.4 Transport of Guest Molecules in Confined Fluids
12.3.5 Transport of Aqueous Electrolytes in Narrow Pores
12.4 Form and Quantity: Confinement Effects on Solubility
12.4.1 Volatile Gas Solubility in Confined Liquids
12.4.2 Aqueous Electrolytes in Confinement
12.4.3 Dielectric Constant of Nanoconfined Water
12.5 Form and Origin: Confinement Effects on Reactivity
12.5.1 General Concept
12.5.2 Methanation of Carbon Dioxide
12.6 Summary and Opportunities
Acknowledgments
Questions for the Classroom
References
13 A Two-Dimensional Perspective on CH4 Isotope Clumping: Distinguishing Process from Source
13.1 Introduction
13.2 Temperature
13.3 Criteria for Intra-CH4 Thermodynamic Equilibrium
13.4 Kinetics
13.5 The Microbial Array
13.6 Is This New Information Helping?
13.7 The Effects of Oxidation on Δ12CH2D2 and Δ13CH3D
13.8 Conclusions
13.9 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
14 Earth as Organic Chemist
14.1 Introduction: The Disconnect between Earth and the Lab
14.2 The Setting for Organic Transformations in the Deep Carbon Cycle
14.3 Hydration/Dehydration as Examples of Elimination Reactions
14.4 Dehydrogenation/Hydrogenation Reactions
14.5 Organic Oxidations
14.6 Amination/Deamination as Examples of Substitution Reactions
14.7 When Organic Molecules Combine: Disproportionation Reactions and Electrophilic Aromatic Substitutions
14.8 Summary of Hydrothermal Organic Transformations
14.9 Organic Reactions in the Deep Carbon Cycle
14.10 Geomimicry as a New Paradigm for Green Chemistry
Questions for the Classroom
References
15 New Perspectives on Abiotic Organic Synthesis and Processing during Hydrothermal Alteration of the Oceanic Lithosphere
15.1 Introduction
15.2 Carbonaceous Matter in Hydrothermally Altered, Mantle-Derived Rocks
15.2.1 Bulk Rock Investigations
15.2.2 In Situ Investigations at the Microscale
15.2.3 Carbon in Fluid Inclusions Trapped in the Oceanic Lithosphere
15.3 Comparison with Experiments and Thermodynamic Predictions
15.3.1 Experimental Approach
15.3.2 Carbon-Bearing Reactants in Experiments
15.3.3 Experimental Occurrences of Carbonaceous Material
15.3.4 Thermodynamic Predictions
15.4 Summary
15.5 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
16 Carbon in the Deep Biosphere: Forms, Fates, and Biogeochemical Cycling
16.1 Introduction
16.2 Oceanic Sedimentary Subsurface
16.2.1 Chemical Composition
16.2.2 Bulk Controls on OM Preservation
16.2.3 Sorption
16.2.4 Oxygen Exposure Time
16.2.5 Models of Organic Carbon Diagenesis
16.3 Oceanic Rocky Subsurface
16.3.1 Characteristics of Recharge Water
16.3.2 Axial High Temperature, Basalt Hosted
16.3.3 Axial Diffuse Vents, Basalt Hosted
16.3.4 Ridge Flanks
16.3.5 Ultramafic Influenced
16.3.6 Fluxes between the Ocean and Crust
16.4 Sedimented Hydrothermal Systems
16.5 Continental Subsurface
16.5.1 Types of Continental Deep Subsurface Environments
16.5.2 Continental Carbon Cycling
16.5.3 Sedimentary and Igneous Aquifers
16.5.4 Hydrocarbon Reservoirs
16.5.5 Deep Coal Beds
16.5.6 Deep Bedrock
16.6 Conclusion
16.6.1 Broad Similarities across Systems
16.6.2 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
17 Biogeography, Ecology, and Evolution of Deep Life
17.1 Subsurface Biomes and Their Inhabitants
17.1.1 Continental Subsurface
17.1.2 Sub-seafloor Sediments
17.1.3 Oceanic Crust
17.1.3.1 Warm Anoxic Basement
17.1.3.2 Cold, Oxic Basement
17.1.4 Ultra-basic Sites
17.1.5 Other Subsurface Environments
17.2 Global Trends in Subsurface Microbiology
17.2.1 Archaea and Bacteria
17.2.2 Subsurface Isolates and Interactions
17.2.3 Subsurface Eukaryotes
17.2.4 Subsurface Viruses
17.3 Subsurface Ecology and Evolution
17.3.1 Physical Extremes in the Deep Subsurface
17.3.1.1 Diffusivity
17.3.1.2 pH
17.3.1.3 Salinity
17.3.1.4 Temperature
17.3.2 Adaptations for Survival at the Extremes
17.3.3 Evolution of Deep Life
17.4 Conclusion
Acknowledgments
Questions for the Classroom
List of Online Resources
References
18 The Genetics, Biochemistry, and Biophysics of Carbon Cycling by Deep Life
18.1 Introduction
18.2 Genetic Potential of Subsurface Environments
18.3 Biogeochemistry of Deep Subsurface Life
18.3.1 Microbial Metabolism in the Deep Subsurface
18.3.2 Predicting Functions of Novel Genes
18.3.3 Cellular Bioenergetics
18.4 Pressure Effects
18.4.1 Extreme Molecular Biophysics
18.4.2 Extreme Cellular Biophysics
18.5 Limits to Knowledge and Unknowns
Acknowledgments
Questions for the Classroom
References
19 Energy Limits for Life in the Subsurface
19.1 Introduction
19.2 Microbial States
19.3 Gibbs Energy: Where It Comes from and How to Use It
19.4 Temperature, Pressure, and Composition Affecting G
19.5 Surveying Gibbs Energies in Natural Systems
19.6 Energy Density
19.7 Time
19.8 The Cost of Anabolism
19.9 Concluding Remarks
Acknowledgments
Questions for the Classroom
References
20 Deep Carbon through Deep Time: Data-Driven Insights
20.1 Introduction: Data and the Deep Carbon Observatory
20.2 Use Case #1: Global Signatures of Supercontinent Assembly
20.2.1 Mineralogical Evidence
20.2.2 Trace Element Distributions
20.2.3 Why Is Rodinian Assembly Unique?
20.2.4 Implications for the Carbon Cycle
20.3 Use Case #2: Carbon Mineral Evolution, Mineral Ecology, and Mineral Network Analysis
20.3.1 Carbon Mineral Evolution
20.3.2 Carbon Mineral Ecology
20.3.3 Carbon Mineral Network Analysis
20.4 Use Case #3: Enzyme Evolution and the Environmental Control of Protein Expression
20.4.1 Network Analysis of Protein Structures: Geo–Bio Interactions on Evolutionary Scales
20.4.2 Network Analysis of Extant Microbial Ecosystems: Geo–Bio Interactions on Ecological Scales
20.5 Conclusions: The Future of Data-Driven Discovery
Acknowledgments
Questions for the Classroom
References
Index