Understanding the 4500 Core-Mantle Boundary Building Blocks of the Planet4000 3500 D” Layer THE MATERIALS SCIENCE OF EARTH PROCESSES3000 7.5 MPa/K ) t 2500 Mantle Adiaba Upper 2000 CMB Mantle (K mperature Te Transition Zone Subduc 1500 Orthorhombic Upper Perovskite Post-Pv tion Mantle 1000 Plume 500 Error ~ 5 GPa Outer Core 0 70 80 90 100 110 120 130 140 150 CMB Inner Core Pressure (GPa) 384 136 23.5 13.5 0 Pressure (GPa) 6370 2890 660 410 0 Depth (km) Hill Top Valley Bottom ~ 8 GPa ~ 250 km Temperature Lower Mantle Pv Depth Pv Pv Warmer Colder PPv PPv PPv CMB Outer Core Long-Range Planning for High-Pressure Geosciences Workshop March 2–4, 2009, Tempe, Arizona Prepared by the Writing Group for Long-Range Financial support for the LRPHPG Workshop Planning for High-Pressure Geosciences was provided by the National Science Foundation • Quentin Williams, Editor (NSF) Division of Earth Sciences. Logistical sup- • J. Michael Brown, Workshop Tri-Chair port for the LRPHGP Workshop was provided by • James Tyburczy, Workshop Tri-Chair the School of Earth and Space Exploration (SESE) of • James van Orman, Workshop Tri-Chair the Arizona State University and the Consortium for • Pamela Burnley Materials Properties Research in the Earth Sciences • John Parise (COMPRES). COMPRES also provided support for • Mark Rivers the preparation and dissemination of this report. • Renata Wentzcovitch Geo Prose provided editing and design assistance. • Robert Liebermann This final report is being submitted to NSF and other federal agencies. This report is drawn from the many presentations and discussions at the Long-Range Planning for High- PREFERRED CITATION Pressure Geosciences (LRPHPG) Workshop held in Williams, Q., ed. 2010. Understanding the Building Tempe, Arizona, on March 2–4, 2009. The workshop Blocks of the Planet: The Materials Science of Earth was attended by 87 members of the mineral phys- Processes. Report to the National Science Foundation. ics and geophysics research communities from 39 COMPRES Consortium, 68 pp. institutions. Initial drafts of this report were openly available and the high-pressure geosciences commu- nity commented on them. The participant list for the LRPHPG Workshop can be found at: http://www.compres.us/index. php?option=com_content&task=view&id= 97&Itemid=123 Understanding the Building Blocks of the Planet The Materials Science of Earth Processes Long-Range Planning for High-Pressure Geosciences Workshop March 2–4, 2009, Tempe, Arizona Contents Executive Summary .......................................................................................................................................................................1 Chapter 1 | Introduction ..............................................................................................................................................................3 Chapter 2 | Earth’s Habitable Surface: A Consequence of the Planet’s Interior ...............................................................8 Key Questions ............................................................................................................................................................................. 12 Chapter 3 | The Magnetic Field, Earth’s Core, and the Deep Mantle ................................................................................ 13 The Magnetic Field and the Habitability of Earth’s Surface ............................................................................................... 13 Iron Alloys—The Phase Relations of Earth’s Innermost Interior: Constraints on Temperature, Composition, and Phase .................................................................................................................................................... 14 Transport Properties of Iron Alloys: Implications for the Sustainability and Energetics of the Geodynamo ........ 16 The Deepest Mantle: The Container of Earth’s Core .......................................................................................................... 18 Key Questions ............................................................................................................................................................................. 21 Chapter 4 | The Third Dimension of Plate Tectonics ........................................................................................................... 22 Thermoelasticity and Seismic Mapping of the Planet ........................................................................................................ 22 The Transition Zone and Mantle Phase Transitions ........................................................................................................... 24 Deeper Transitions? ................................................................................................................................................................... 26 Thermal and Electrical Conductivity of Mantle Minerals: How Does the Mantle Homogenize and Transport Heat and Electrons? ................................................................................................................................. 27 Chemical Diffusivity and Viscosity: How Does the Mantle Mix and Flow? ................................................................... 29 Properties of Planetary Fluids—Magmas and Metasomatism ......................................................................................... 30 Linkages Between the Deep Earth and the Lithosphere: Deeply Derived Magmas, Heat Sources, and Metamorphism .................................................................................................................................. 32 Key Questions ............................................................................................................................................................................. 34 Chapter 5 | Other Planets, Other Interiors ............................................................................................................................ 35 Terrestrial Planets and Large Moons ..................................................................................................................................... 35 Solar System Satellites and Minor Planets ............................................................................................................................ 38 Large Planets: H-rich Systems at Ultra-Extreme Conditions ........................................................................................... 39 Exoplanets: New Frontiers of Size, Thermal Regime, and Composition ........................................................................ 40 Key Questions ............................................................................................................................................................................. 41 Chapter 6 | The Invisible Frontier: Creating the Conditions of Earth and Planetary Interiors .................................... 42 Static, High-Pressure Techniques ........................................................................................................................................... 43 Shock-Loading Techniques ...................................................................................................................................................... 46 Theoretical Approaches to High-Pressure Geosciences .................................................................................................... 48 Key Technique-Oriented Goals............................................................................................................................................... 51 Chapter 7 | Broader Impacts: New and Complex Materials at High Pressures ............................................................... 52 Ultra-Hard Materials ................................................................................................................................................................. 52 Radioactive Waste Immobilization ........................................................................................................................................ 53 Energy Storage and Climatic Issues ........................................................................................................................................ 54 Key Prospects .............................................................................................................................................................................. 56 Chapter 8 | Future of the Field: Building our Community ................................................................................................. 57 Recommendations for New Community Experimental and Computational Infrastructure ..................................... 57 Maintaining and Enhancing Access to State-of-the-Art Beamlines ................................................................................ 60 Improving Educational Materials and Community Outreach/Recruitment ................................................................. 64 Future Educational Directions................................................................................................................................................. 65 Future Community-Building Goals ........................................................................................................................................ 66 References ...................................................................................................................................................................................