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