Raymond Jeanloz - US grants

The PI will provide new constraints on the strength and creep rheology of the Earth's mantle by carrying out experiments on crystalline and amorphous minerals at pressure-temperature conditions ranging up to 100 GPa and 5000K. Novel experimental techniques developed in this laboratory during the past few years now make such research possible. Results at room temperature already demonstrate that rheology is significantly affected by pressure and by pressure-induced transformations, both in crystalline and in metastable liquid (i.e., glassy) phases. The work would provide the first experimental constraints on global deformation processes, with far-reaching implications for our understanding of the thermal, chemical, and geodynamic evolution of the Earth.

This proposal describes a 2-year program to experimentally investigate the petrology of the lower mantle, the single largest region of the earth. Using the laser-heated diamond cell, a natural garnet peridotite composition will be taken to P-T conditions existing throughout the lower mantle . A combination of in situ X-ray diffraction and quenched-product analysis will be used to determine: (1) the identity and quantity of major phases present; (2) the major-element partitioning between these phases as a function of pressure; (3) the equations of state of the phases, and hence of the assemblage for direct comparison with the seismological profiles of the lower mantle; and (4) the solidus temperature of the assemblage from which tight constraints on the deep-mantle geotherm could be obtained. Year 1 will concentrate on sub-solidus equilibria, and Year 2 will concentrate on solidus/liquidus equilibria of the natural peridotite composition as well as reconnaissance (solid-state and liquid) equilibria of an iron-enriched composition. These experiments are a direct extension of techniques used in prior work that successfully determined the ultrahigh P/T equilibria of individual natural minerals, and they would represent the first time that an actual rock assemblage had been studied at the conditions existing throughout the bulk of the mantle.

This award provides support for the acquisition and modification of components into a microdensitometer system for measuring the intensities of diffracted x-rays as recorded on x- ray sensitive film. The instrument will be developed and installed in the Department of Geology and Geophysics at the University of California at Berkeley. It will be used primarily in the characterization of materials subjected to ultra-high pressures during laboratory experiments intended to mimic conditions inside the Earth's deep interior.

This award provides partial funding for the upgrade of a Fourier Transform Infrared spectrometer system in the Department of Geology and Geophysics at the University of California in Berkeley. The University is committed to providing a match of 33% of the costs of the equipment for this project. The upgrade project will consist of renovation of the source, drive and electronic components of the existing system, a new microscope system for improved microsampling, and the development of a novel detector design for microspectroscopy. The upgrade will allow better spectroscopic characterization of phase changes and properties of earth materials subjected to ultra-high pressures (simulating conditions in the Earth's deep interior) during laboratory experiments inside a diamond-anvil pressure cell.

9304986 Jeanloz This project initiates a community-wide study of the core-mantle boundary, one of the most significant regions of our planet. As a result of the past decade's research advances, the geosciences community is on the verge of making significant breakthroughs in understanding how the Earth evolves on a global scale. Because the dynamics of the deep planetary interior involves many different facets of the Earth sciences, from geomagnetism and seismology to mineral physics and geodynamics, a multi-disciplinary approach is essential. An average of less than $30 K/yr for each investigator will allow them to pursue this effort in a truly collaborative and interdisciplinary manner. This project will yield important new observations and theoretical analyses bearing on the core-mantle boundary, and will support the participation of the broader community of interested geoscientists. Significant advances in our understanding of the Earth's geological evolution -- far beyond what would be achieved by the individual groups working separately -- will result from this collaborative, multi-disciplinary effort. ***

9305219 Jeanloz This award supports a 2-year collaborative research program intended to elucidate the elastic properties of majorite, the garnet-structured high-pressure phase of pyroxene that is an important constituent of the transition zone in the Earth's mantle. The study would check previous measurements that are controversial, resolving whether or not the properties of majorite are anomalously sensitive to details of composition, crystallographic structure, ordering or origin. Resolving this issue is critical to understanding the geophysical properties of the mantle transition zone. The work would also provide a significant cross-check between two laboratories and between two methods of determining elastic properties on polycrystalline aggregates, Brillouin spectroscopy and static compression. For the first time, natural samples of transition-zone high-pressure phases would be made available to the community for complementary studies through modern techniques of chemical and physical micro- analysis. ***

9316495 Carmichael This award provides 71% of the funding necessary for the acquisition of a new electron microprobe that will be installed and operated in the Department of Geology and Geophysics at the University of California-Berkeley. The University is committed to providing the remaining funds necessary to acquire this instrument. The electron microprobe is a versatile electron beam instrument capable of accurate analysis of chemical composition of solids for major element constituents to trace elements and has an analytical spatial resolution on the sample target of a micrometer. The new UC-Berkeley electron microprobe will be primarily used by research groups in the Department of Geology and Geophysics, the Lawrence Berkeley Laboratory, other campus and off-campus groups with research needs for microanalysis of solids. ***

9315036 Crawford This award will support a graduate student to investigate the feasibility of using naturally occurring neutrinos to map the density distribution through the Earth's mantle and core. Theoretical investigations show that it is possible to determine variations in density - and possibly composition - as a function of depth by measuring the absorption of neutrinos passing through the planet. By taking advantage of the initial deployment of the DUMAND II detector array, the PIs and graduate student will be able to document experimentally the practical utility of this method. The outcome of this project could revolutionize our understanding of the geodynamical and geochemical evolution of the Earth's deep interior. ****

Jeanloz 9527021 The PIs propose an experimental investigation of the thermal equation of state of perovskitite, the high-pressure perovskite-bearing asemblage of minerals thought to dominate the petrology of the lower mantle. The experiments will involve high-pressure, high-temperature determinations of P-V-T relations using synchrotron radiation, and the results should allow testing of models of distinct bulk composition for the earth's upper and lower mantle.

9710472 Jeanloz The PIs will address two major geological questions using a combination of high-pressure experiments (both multi-anvil devices and laser-heated diamond cells) and first-principles quantum-mechanical calculations: 1) How does the redox state affect the relative stability of the major constituents of the mantle and core? and 2) How does the redox state effect the partitioning of geophysically and geochemically important elements among major mantle and core phases? Their objective is to develop new avenues of research regarding the Earth's redox state, ranging from the practical to the fundamental: for example, from developing means of characterizing and controlling redox state in experiments at ultrahigh pressures (P) and temperatures (T), to understanding the meaning of a component's fugacity at P-T conditions far above the critical point. Multi- institutional collaboration will be an important aspect of this research both because of the diversity of state-of-the-art experimental and theoretical methods to be employed (no one or two groups have sufficient expertise), and because this will allow significant cross-checks of the results between different laboratories, between different experimental methods, and between theory and experiment. ***

9725898 Jeanloz This grant provides partial support to upgrade the ruby fluorescence spectrometer at the UC-Berkeley high-pressure laboratory with a charge-coupled device (CCD). The ruby fluorescence spectrometer is used to rapidly determine pressure and pressure variations across very small samples (50-500 microns) inside diamond anvil cells (DAC). Accurate determination of the pressure distribution within a DAC allows calculation of shear stresses within the cell and/or viscous stress relaxation of materials that have been laser heated in conjunction with high pressure DAC experiments. The current detector for UC-Berkeley ruby fluorescence system is an antiquated photomultiplier tube (PMT) that has exceeded its estimated 10 yr. life span. New PMT's are currently manufactured on a made-to-order basis only and have therefore increased in price over the years as digital CCD's have entered the market and become more affordable. While still less expensive than CCD detectors, PMT's are far less sensitive to emitted EM radiation and cannot be used in experiments requiring pressures exceeding 60-70 GPa where sample sizes are necessarily very small and emitted fluorescence is therefore weak. PMT detectors thus limit high P-T experiments to upper mantle conditions. Additionally, a CCD array can later be adapted for use in Raman spectroscopy A ruby fluorescence spectrometer is a required tool in DAC experimentation and the PI's choice of a CCD detector to replace his PMT is well reasoned and forward looking. This upgrade will allow this PI, his students and colleagues to continue provocative research aimed at understanding early Earth and planetary differentiation and the structure of high pressure mantle phases and synthetic materials. ***

Jeanloz

0001087



Understanding the properties of H2O deep inside the Earth has major implications for deciphering the geochemical cycling of water and the possible initiation of melting inside the planet, as well as the geophysically observed properties of the mantle. Thermodynamic analysis even suggests that ice may be present at depth, subducted within cold rapidly-sinking slabs. The proposal requests support for a 2-year experimental effort intended to document 1) the crystal-structural identity, 2) thermal equation of state and 3) melting temperature of crystalline H2O (Ice VII, and potentially other polymorphs) at high pressures and temperatures, providing fundamental constraints on the stability and the geophysically relevant properties (elasticity, density) of H2O phases at lower-mantle pressures, ~20-80 GPa.

EAR-0112484
Jeanloz
Shimizu

The investigators propose to conduct a 2-year collaborative study between high-pressure experimental geophysicists at the University of California at Berkeley and analytical geochemists at Woods Hole Oceanographic Institution. This research will experimentally evaluate the feasibility and validate the measurement of trace-element partitioning between metal and silicate at the high pressures and temperatures of the Earth's deep mantle and core, ~100 GPa and 4000 K. The possibility of combining the capability of the laser-heated diamond cell, to reproduce conditions of the planetary interior, with that of secondary ion mass spectrometry (SIMS), for measuring isotopic abundances at the ppm level and below on spatial scales of ms, will be evaluated. If successful, these combined tools can be used as a means of resolving major issues in geochemistry and geophysics that depend on understanding the distribution of trace elements within the mantle and core. Such studies are crucial for determining the potential consequences of chemical interactions between the core and mantle over geological time and, more generally, for deciphering the evolution of the Earth's deep interior. The experiments proposed here are intended to help develop methodologies for element-partitioning studies to be pursued in the future.

Raymond Jeanloz
EAR-0126217

The occurrence of deep-focus earthquakes remains one of the great mysteries of geophysics because laboratory experiments demonstrate that materials become ductile at the pressures of the Earth's deep interior. How then can rock undergo brittle rupture at the pressures of the deepest earthquakes, some 0.25 million atmospheres? The proposal requests support for a 3-year effort intended to develop and then begin applying a new experimental method for characterizing acoustic emissions generated from samples at high pressures. An array of GHz-frequency sensors is to be attached to a diamond-anvil cell in order to characterize the elastic-energy released by high-pressure phase transitions in mantle minerals and their analogs. The work combines proven technologies (acoustic-emission recording and GHz ultrasonics with the diamond cell), and shows considerable promise for future development of a large variety of complementary methods (optical, spectroscopic, diffraction) for characterizing brittle failure in detail and under a wide range of conditions.

The investigators seek to advance the creation of a Cooperative Institute for Deep Earth Research (CIDER). This award will provide funds to hold a series of 2 workshops over a period of one to two years whose goal will be to define the scope and activities of a possible future CIDER. The workshops will be interdisciplinary in nature and will address the question of global Earth structure, evolution, and dynamics. Participation will be open to the community. The direct product of each workshop will be a report listing the key questions identified during the workshop, whose resolution requires an interdisciplinary approach, as well as recommendations for the activities and structure of the future CIDER. These documents will then be used as a basis for the preparation of a detailed proposal for the establishment of CIDER.

The Cooperative Institute for Dynamic Earth Research has been conducting 6-7 week long bi-annual summer programs since 2004 to foster synergies between individual and small groups of researchers. The goal is to help improve fundamental understanding of the Earth's evolution and present dynamics through a multi-disciplinary approach that facilitates cross-education among the disciplines involved: seismology, geochemistry, geodynamics, mineral physics and geomagnetism. CIDER facilitates cross-education of earth scientists at any level in their career. Included in the summer programs are 3-4 weeks of lectures, tutorials and working group activities that contribute to the multi-disciplinary education of graduate students and post-docs in all disciplines of solid earth sciences. The work of CIDER will ultimately impact how to better address two key natural hazards issues of societal relevance: (1) natural hazards such as earthquakes and volcanic eruptions; and (2) the whole-Earth budget of volatile elements, especially water and carbon dioxide.

Phase II of CIDER builds upon 5 years of experience with CIDER Phase I: three summer programs in 2004, 2006 and 2008, and input from a community workshop held at the Marconi Center, CA, May 2009 (which recommended continuation and expansion of CIDER programs) and an on-going 2010 summer program. These programs have all focused on 'deep Earth' science themes. Phase II of CIDER includes a 6 week long summer program to be held at UC Berkeley from June 27th to August 6th, 2011 on the theme 'The dynamics of mountain building', expanding the reach of CIDER to the multi-disciplinary community working on near-surface earth processes. In addition, it expands the activities of CIDER in two areas: 1) follow-up research started by multi-disciplinary working groups during the Summer programs held in 2010 and 2011; 2) expansion of the CIDER web capabilities, in particular, to experiment with and develop a supporting virtual organization.

The Center for Matter at Atomic Pressures (CMAP) is a new NSF Physics Frontiers Center that explores matter at pressures strong enough to change the nature of atoms themselves. Such conditions have not been explored or exploited on Earth, yet they dominate the interiors of planets and stars. To date, thousands of planets have been discovered, providing numerous possible platforms for life throughout the universe. To understand the origin, evolution, and nature of these planets, one has to understand properties of high energy density matter at and beyond atomic pressures. CMAP will use powerful lasers, pulsed-power, and x-ray beam facilities to recreate and characterize matter under the extreme conditions of the deep interiors of planets and stars. CMAP brings together a diverse team, spanning disciplines from plasma physics, condensed matter, and atomic physics to astrophysics and planetary science, to address gaps that limit our understanding of most of the atomic and chemical constituents of the Universe. CMAP aims to develop a new discipline of physics at extreme pressures, combined with the most advanced laboratory and theoretical capabilities available, to train tomorrow?s science leaders. CMAP?s research, education and outreach programs aim to bring a new understanding of the universe to the public and inspire and engage a new generation of scientists of all ages and backgrounds.

The NSF Physics Frontiers Center for Matter at Atomic Pressures will exploit a new generation of laboratory capabilities -- kilo-joule to Mega-Joule lasers, tens of Mega-Amp pulsed power, and advanced x-ray facilities -- and first-principles theory to explore the properties of matter under the high energy density conditions that exist in the deep interiors of planets and stars. CMAP will explore the nature and astrophysical implications of matter extending to and beyond the atomic unit of pressure, the pressure determined by the Hartree energy and Bohr radius, conditions that disrupt the electronic-shell structure of atoms, engage core electrons in bonding, and unlock a regime in which electron and ion quantum correlations can grow to macroscopic scales at high temperatures. Atomic pressure is a fundamental physical unit that remains unexplored. CMAP will bring together experts in plasma, atomic, and condensed matter physics leading to new discoveries and breakthroughs in physics. To do so, the CMAP team has a particular focus on excellence through diversity, and on convergence of research, education, and broad outreach efforts.

This Physics Frontiers Centers award is co-funded by the Division of Physics in the Directorate for Mathematical and Physical Sciences and the Division of Earth Sciences in the Directorate for Geosciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.