Magma Redox Geochemistry

Redox chemistry is a reflection of magma composition, and the understanding of magma’s physico-chemical nature is the basic pre-requisite to understand how redox exchanges work in deep Earth systems. Redox geochemistry, magmatism and volcanism addresses the concepts and methods that redox geochemistry uses for understanding magma formation, ascent, evolution, and crystallization.

Volume highlights include:

• Knowledge of redox mechanisms acting in volcanism and hydrothermalism which has a great impact on the socio-economical development of human societies because of their key-role in volcanic hazard assessment, geothermal energy exploration and ore deposits formation
• Studies of influence of volatile components and their redox control on volcanic degassing and metal mobility
• Elements in the silicate liquid geochemistry of silicate melts and magma genesis and focusing on how their properties are influenced
• Assessment of the role of redox variable in volcanism, including hydrothermal systems, degassing issues and ore deposits formation
• Illustrative importance of redox state to move a step forward towards the knowledge of stable isotope fractionation, particularly of non-traditional isotopes
• Advances in experiments and theory revealing new insights into the atomic structure and macroscopic properties of silicate glasses and melts, the evolution of magmas, and processes operating at spreading centers and subduction zones 

This volume highlights the benefit of redox studies on the geodynamics of magma production and consumption as well as for constraining and advancing our knowledge of the formation and evolution of the Earth. Redox geochemistry, magmatism and volcanism is a valuable resource in the fields of geochemistry, mineralogy, igneous petrology, geomaterials, geodynamics, natural hazards, volcanology and environmental chemistry.

Roberto Moretti, Université de Paris, Institut de Physique du Globe de Paris, France

Daniel R. Neuville, Université de Paris, Institut de Physique du Globe de Paris, France

List of Contributors

Preface

1. Redox Equilibria: From Basic Concepts to the Magmatic Realm
Roberto Moretti and Daniel R. Neuville

Part I Redox from the Earth’s Accretion to Global Geodynamics

2. Redox Processes Before, During, and After Earth’s Accretion Affecting the Deep Carbon Cycle
Vincenzo Stagno and Sonja Aulbach

3. Oxygen Fugacity Across Tectonic Settings
Elizabeth Cottrell, Suzanne K. Birner, Maryjo Brounce, Fred A. Davis, Laura E. Waters, and Katherine A. Kelley

4. Redox Variables and Mechanisms in Subduction Magmatism and Volcanism
Katy A. Evans and Andy G. Tomkins

5. Redox Melting in the Mantle
Stephen F. Foley

Part II Redox at Work: From Magma Sources to Volcanic Phenomena

6. Ionic Syntax and Equilibrium Approach to Redox Exchanges in Melts: Basic Concepts and the Case of Iron and Sulfur in Degassing Magmas
Roberto Moretti

7. The Petrological Consequences of the Estimated Oxidation State of Primitive MORB Glass
Paul D. Asimow

8. Oxygen Content, Oxygen Fugacity, the Oxidation State of Iron, and Mid-Ocean Ridge Basalts
Andrew J. Berry and Hugh St.C. O'Neill

9. Chromium Redox Systematics in Basaltic Liquids and Olivine
Aaron Bell

10. The Thermodynamic Controls on Sulfide Saturation in Silicate Melts with Application to Ocean Floor Basalts
Hugh St.C. O’Neill

11. Redox State of Volatiles and Their Relationships with Iron in Silicate Melts: Implications for Magma Degassing
Nicole Métrich

12. Iron in Silicate Glasses and Melts: Implications for Volcanological Processes
Charles Le Losq, Maria Rita Cicconi, and Daniel R. Neuville

Part III Tools and Techniques to Characterize the Redox and its Effect on Isotope Partitioning

13. How to Measure the Oxidation State of Multivalent Elements in Minerals, Glasses, and melts?
Daniel R. Neuville, Maria Rita Cicconi, and Charles Le Losq

14. Oxidation State, Coordination, and Covalency Controls on Iron Isotopic Fractionation in Earth’s Mantle and Crust: Insights from First-Principles Calculations and NRIXS Spectroscopy
Marc Blanchard and Nicolas Dauphas

15. The Role of Redox Processes in Determining the Iron Isotope Compositions of Minerals, Melts, and Fluids
Paolo A. Sossi and Baptiste Debret

16. Zinc and Copper Isotopes as Tracers of Redox Processes
Edward C. Inglis and Frédéric Moynier

17. Mineral-Melt Partitioning of Redox-Sensitive Elements
Guilherme Mallmann, Antony Burnham, and Raul Fonseca

18. Titanomagnetite – Silicate Melt Oxybarometry
Róbert Arató and Andreas Audétat

19. The Redox Behavior of Rare Earth Elements
Maria Rita Cicconi, Charles Le Losq, Grant Henderson, and Daniel R. Neuville