Mineral Physics Research Articles

Development of a SaaS application probe to the physical properties of the Earth's interior

Scientific computing often requires the availability of a massive number of computers for performing large-scale simulations, and computing in mineral physics is no exception. In order to investiga...

GEOLIFE – Geomaterials for the environment, technology and human activities. Preface to the October 2014 special set of papers arising from presentations at the Goldschmidt 2013 conference

This special issue of the Mineralogical Magazine springs from the session we organized as part of the Goldschmidt 2013 conference in Florence. The title we proposed “GEOLIFE – Geomaterials for environment, technology and human activities” reflects our feeling that a wise use of the expertise gained by mineralogists while studying the crystal chemistry, as well as the chemical and physical properties of minerals in rocks and soils, still plays an important role in what is called “The cutting edge in Mineralogy and Mineral Physics”.Indeed, the current expertise in the physical, chemical and structural characterization of geomaterials, i.e. minerals, rocks and their synthetic analogues, now allows us to design innovative applications both for technological and environmental purposes. During the meeting we discussed some frontier work on phases produced naturally by the Earth ‘laboratory’ or fabricated within academic laboratories, which have the potential to improve the quality of life for current and future generations.

Hansen, Murphy, Receive Mineral and Rock Physics Graduate Research Awards

Lars N. Hansen and Caitlin A. Murphy were awarded the 2013 Mineral and Rock Physics Graduate Research Award, given annually to one or more promising young scientists for outstanding contributions achieved during their Ph.D. research. Recipients of this award are engaged in experimental and/or theoretical studies of Earth and planetary materials with the purpose of unraveling the physics and chemistry that govern their origin and physical properties.

In situ TEM observations of plastic deformation in quartz crystals

With in situ nanocompression experiments in a transmission electron microscope, we investigated plastic deformation in natural quartz crystals and observed both dislocation plasticity as well as mechanical twinning. Through this experimental method, we are able to provide direct evidence of Dauphine twin nucleation and could measure the intrinsic twinning stress. The twinning phenomena appear to include a memory effect, where the same twin can reappear upon successive loading and unloading events. The data provide insight into this twin generation mechanism and can be used as a benchmark for the use of twins in quartz for paleopiezometry. Together, the observation of room-temperature dislocation plasticity and reversible twinning adds new insight into the extensive field of quartz plasticity and demonstrates the usefulness of small-scale testing techniques for mineral physics.

Development of a SaaS application probe to the physical properties of the Earth׳s interior: An attempt at moving HPC to the cloud

Scientific computing often requires the availability of a massive number of computers for performing large-scale simulations, and computing in mineral physics is no exception. In order to investigate physical properties of minerals at extreme conditions in computational mineral physics, parallel computing technology is used to speed up the performance by utilizing multiple computer resources to process a computational task simultaneously thereby greatly reducing computation time. Traditionally, parallel computing has been addressed by using High Performance Computing (HPC) solutions and installed facilities such as clusters and super computers. Today, it has been seen that there is a tremendous growth in cloud computing. Infrastructure as a Service (IaaS), the on-demand and pay-as-you-go model, creates a flexible and cost-effective mean to access computing resources. In this paper, a feasibility report of HPC on a cloud infrastructure is presented. It is found that current cloud services in IaaS layer still need to improve performance to be useful to research projects. On the other hand, Software as a Service (SaaS), another type of cloud computing, is introduced into an HPC system for computing in mineral physics, and an application of which is developed. In this paper, an overall description of this SaaS application is presented. This contribution can promote cloud application development in computational mineral physics, and cross-disciplinary studies.

Report of the IMA Commission on the Physics of Minerals 2011–2014

the members of the CPM and its four sub-commissions have been active in organizing and convening sessions in all of the Goldschmidt conferences held during the period 2011– 2014. For example, during the Goldschmidt conference held in Florence, Italy, in august 2013, they co-organized the following themes: “the cutting edge in mineralogy and mineral physics”, “Deep Earth”, and “Melts, glasses, magmas: from properties to processes”. Under these themes, the following sessions were co-convened by CPM members: “High-pressure mineral physics: a key to study Earth’s dynamics”, “Deep transport of subducted material: escaping the meat grinder”, and “latest news on the structure of melts and glasses”. In addition to the above activities, CPM members convened sessions in many international and national meetings of societies and other organizations and delivered keynote and invited talks (e.g. aGU, EGU, JPGU, aOGS, COMPrES, WPGM 2012, XXV IUGG General assembly 2011, and SMEC meetings 2011 and 2013). Many CPM members play key roles in organizations focusing on mineral physics and related fields, including as section president and committee members of sections and focus groups of aGU, president of COMPrES, section president of JPGU, and committee members of national societies involving mineralogy and mineral physics. through all of these activities, the CPM and its members have contributed significantly to the promotion of mineral physics and geodynamics at both national and international levels.

Kaolin-Group Minerals: From Hydrogen-Bonded Layers to Environmental Recorders

Kaolin-group minerals typically form as a result of hydrothermal alteration and/or weathering processes. They occur in environments as diverse as tropical soils, continental sedimentary deposits, and altered crustal rocks. They have also been detected on the surface of Mars. Given their prevalence, they have attracted the attention of researchers in materials chemistry, environmental geochemistry, and high-pressure mineral physics. Their structure and related properties have been studied for about a century, and these studies reflect advances in experimental techniques, modeling approaches, and concepts in mineralogy. Among key features of their structure are the predominance of 2-D stacking defects and the peculiar role of H-bonding in the control of their polytypism.

Presentation of the Mineralogical Society of America Award for 2013 to Wendy Li-Wen Mao

Fellow mineralogists, I am honored to present to you Wendy Li-Wen Mao, a friend and colleague of mine in the Department of Geological and Environmental Sciences at Stanford University as well as the Department of Photon Science at SLAC National Accelerator Laboratory. Wendy is receiving the 2013 MSA Award for her exceptional contributions to the field of mineral physics. However, before I tell you about Wendy’s blossoming scientific career and her many outstanding scientific contributions, I would like to share a few personal things I have learned about Wendy from Agnes Mao, her mother who is here today, and from my own observations of Wendy over the past six years. According to Agnes, Wendy was a quiet and exceptionally well-behaved baby, in contrast to Wendy’s 5-month old son, whom I call “Action Jackson”. Action Jackson is in the audience with his father Benson. According to Wendy, Jackson has kept her awake most nights since his birth. Agnes also told me that Wendy loved to collect things as a child, including minerals, coins, stamps, and Cabbage Patch dolls. I can vouch for this because every flat surface in Wendy’s office at Stanford is covered by things she has collected recently, including many pieces of serpentine and other minerals, …

Acceptance of the Mineralogical Society of America Award for 2013

Thank you so much, Gordon, for those kind words. Mr. President, members of the society, and guests: It is a great honor to be receiving the MSA award and also to share the stage with the Roebling Medalist Frank Hawthorne and Distinguished Public Service Awardee Pierrette Tremblay. Reading over the citations and acceptance speeches of the previous MSA award recipients was really fascinating. I know I sound like a broken record saying that I feel humbled looking at the list of previous awardees, but I would be remiss not to. It is a really impressive group, and frankly I feel a lot of pressure recognizing how much the previous recipients have accomplished. On paper it probably looks like I was born into mineralogy since as a child some of my most vivid memories are of playing on the weekends in the old Geophysical Laboratory building, but I actually came to mineral physics in a bit of a roundabout manner. My older sisters and I were all convinced that we had no interest in doing what our father did. My …

BurnMan: A lower mantle mineral physics toolkit

We present BurnMan, an open-source mineral physics toolbox to determine elastic properties for specified compositions in the lower mantle by solving an Equation of State (EoS). The toolbox, written in Python, can be used to evaluate seismic velocities of new mineral physics data or geodynamic models, and as the forward model in inversions for mantle composition. The user can define the composition from a list of minerals provided for the lower mantle or easily include their own. BurnMan provides choices in methodology, both for the EoS and for the multiphase averaging scheme. The results can be visually or quantitatively compared to observed seismic models. Example user scripts show how to go through these steps. This paper includes several examples realized with BurnMan: First, we benchmark the computations to check for correctness. Second, we exemplify two pitfalls in EoS modeling: using a different EoS than the one used to derive the mineral physical parameters or using an incorrect averaging scheme. Both pitfalls have led to incorrect conclusions on lower mantle composition and temperature in the literature. We further illustrate that fitting elastic velocities separately or jointly leads to different Mg/Si ratios for the lower mantle. However, we find that, within mineral physical uncertainties, a pyrolitic composition can match PREM very well. Finally, we find that uncertainties on specific input parameters result in a considerable amount of variation in both magnitude and gradient of the seismic velocities.

Missing link in mantle dynamics

The discovery of crystallographic imperfections known as disclinations in the most profuse mineral in Earth's upper mantle has the potential to solve a problem that has vexed mineral physicists for decades. See Article p.51 Olivine is the most abundant upper-mantle mineral — and the weakest under a wide range of thermo-mechanical conditions — so its deformation under stress is an important constraint on mantle behaviour. Patrick Cordier et al. present a model for the deformation of olivine aggregates that includes the motion of rotational defects — referred to as 'disclinations' — a factor neglected in previous studies of mantle rheology. The authors conclude that such disclination motion could provide the missing mechanism for describing plastic flow in olivine, which should enable multiscale modelling of the rheology of the upper mantle, from the atomic scale to large-scale mantle flow.

Elasticity of lawsonite and seismological signature of metamorphism and water cycling in the subducting oceanic crust

AbstractThe elastic properties of lawsonite determined from equations of state, Brillouin scattering, acoustic velocity measurements, and first‐principles calculations are reviewed. Equations of state are essential for thermodynamic modelling of phase equilibrium at high pressure. Elastic tensor determinations allow calculation of the seismic properties of isotropic rocks, and of anisotropic rocks when combined with CPO determinations. Potential effects of low‐T, high‐P phase transitions in lawsonite on extrapolations to deep‐Earth conditions are discussed. Seismological data suggest that metamorphic zoning in active cold subduction zones can be resolved as low velocity layers down to 250 km. Mineral physics and phase equilibria indicate that lawsonite is the best candidate for explaining such low velocities. These layers are likely the image of water recycling to the deep mantle in subduction zones.

Global radially anisotropic mantle structure from multiple datasets: A review, current challenges, and outlook

Abstract Since the 1960s seismologists have mapped anisotropy in the uppermost mantle, the mantle transition zone, and the D″ region. When combined with constraints from mineral physics and geodynamics, anisotropy provides critical information on the geometry of mantle flow. Here we review the theory, early work, recent tomographic models, and experimental constraints on radial anisotropy. We discuss current challenges in resolving radial anisotropy seismically. In particular, we show that it is highly beneficial to use multiple datasets in inversions for anisotropy, notably short-period group velocity data with strong sensitivity to the crust. We present a new whole-mantle model of radial anisotropy, based on surface-wave and body-wave travel time data, along with incorporated Moho perturbations. Our whole-mantle model shares common features with previous global models and is consistent with results from several high-resolution regional studies.

Can downwelling at the top of the Earth’s core be detected in the geomagnetic secular variation?

It has been argued based on recent seismic and mineral physics studies that the top of Earth’s liquid outer core is stably stratified. Here I analyze persistent geomagnetic secular variation features on the core–mantle boundary to examine whether a kinematic signature of core fluid upwelling/downwelling can be detected. I focus on regions of intense high-latitude geomagnetic flux patches that may be maintained by fluid downwelling. In order to identify persistent patterns, the radial field and its secular variation are stacked in the flux patch moving reference frame. These stacked images are compared with forward solutions to the radial induction equation based on idealized field-flow models. Clear advective secular variation signature below North America indicates that these intense flux patches may exhibit significant mobility. Stretching signature in the form of persistent positive secular variation correlated with the intense flux patch below the Southern Indian Ocean may be considered as regional scale geomagnetic evidence for whole core convection, although pure toroidal flow cannot be outruled.

Physical state of Himalayan crust and uppermost mantle: Constraints from seismic attenuation and velocity tomography

AbstractWe jointly interpret P and S wave seismic attenuation (1/Q) along with previously published seismic velocity results for the crust and uppermost mantle of eastern Nepal and the southern Tibetan Plateau. Seismic attenuation measurements can provide information complementary to seismic velocity estimates and can help distinguish between compositional and thermal mechanisms for observed anomalies. In addition to a dramatic change in seismic velocity observed between the crust of Nepal and southern Tibet, we find a large increase in seismic attenuation from high Q (low attenuation) in eastern Nepal to low Q (high attenuation) in the crust beneath southern Tibet for both P waves and S waves. We interpret the broad zone of low Q values in the southern Tibetan crust as thermal in origin, requiring an elevated geotherm (warm) relative to Nepal, with low VP/VS corresponding to a dominantly felsic middle and upper crust beneath southern Tibet. We find a sharply bounded region with enhanced low Q and high VP/VS at 45–50 km depth beneath southern Tibet, which we suggest may be due to trapped fluid beneath an impermeable cap associated with the crustal alpha‐beta quartz transition. Using calibrations from mineral physics, the alpha‐beta quartz transition suggests a temperature of 930–960°C at 45 km depth (50 km beneath the surface) beneath the southern Tibetan Plateau. High values of QP and QS throughout the uppermost mantle in the region are consistent with cool temperatures in the underthrusting Indian Plate, contributing to brittle conditions and earthquakes in the uppermost mantle.

Carryover of Sampling Errors and Other Problems in Far-Infrared to Far-Ultraviolet Spectra to Associated Applications

The thin, smooth curves representing spectroscopic data suggest a high degree of accuracy. Yet, experimental uncertainties do exist, as in any measurement. Overlooked problems in data collection, processing, and interpretation have repercussions for applications in mineral physics, planetary science, and astronomy. Random errors (i.e., noise) are fairly obvious, and are not discussed here. The concern is subtle and overlooked errors that arise in acquisition, processing, and interpretation of spectral data. These types of errors are systematic, not random. This chapter identifies various systematic errors and problems that the author encountered in her efforts to provide absolute values of absorbance or reflectivity. Re-occurring issues in data collection include underestimating the importance of surface polish and not accounting for peak profiles depending on sample thickness relative to band strengths. Processing of emission spectra is problematic. Common instrumental problems are briefly described. Optical spectroscopy is the name generally attached to the visible region which we probe with our eyes, which are convenient built-in spectrometers, but can also include the infrared (IR) region wherein the type of vibrational mode known as “optical” is detected. Because some applications require very high frequency (ν) data, this chapter concerns ν from ~10 to 106 wavenumbers, which is equivalent to wavelengths (λ) of ~106 to 10 nm or of ~1000 to 0.01 μm). The X-ray region is included due to the extreme breadths of metal-oxygen charge-transfer bands of minerals which peak in the ultraviolet (UV). The author points out errors in her own results as well those of others. Mistakes provide opportunity for learning! Correct methodologies are discussed along with measurements needed to improve constraints on spectral parameters and hence to make interpretations more definitive. Ideal conditions are difficult to achieve, so another goal is enable the reader to recognize what is “sufficiently accurate” and/or “representative” …

Probing of Pressure-Induced Bonding Transitions in Crystalline and Amorphous Earth Materials: Insights from X-ray Raman Scattering at High Pressure

Knowledge of the electronic structure of crystalline and non-crystalline earth materials at ambient and high pressure are essential in order to understand the atomic origins of electronic, thermodynamic, and mechanical properties of these materials in the Earth’s crust as well as Earth and planetary interiors (Hemley 1998; Laudernet et al. 2004; Stixrude and Karki 2005; Mao and Mao 2007; Price 2007; Stixrude 2007). Pressure-induced changes in the electronic structure of crystalline and amorphous silicates and oxides (glasses and melts) with low- z elements (e.g., Si, O, B, Li, C, etc.) have implications for diverse geophysical and magmatic processes relevant to the evolution and differentiation of the earth (e.g., mantle convection and mantle melting) (Stebbins 1995; Wolf and McMillan 1995; Lee 2005, 2011; Mysen and Richet 2005; Murakami and Bass 2010). Despite this importance, the analysis of the effect of pressure on the electronic structure and the nature of bonding in the crystalline and, particularly, non-crystalline oxides has remained one of the challenging problems in mineral physics and geochemistry, as well as, condensed matter physics. This is mostly because of the lack of suitable experimental probes of electronic bonding around these light elements in the earth materials under pressure. Advances in in situ high pressure technologies, together with progress in X-ray optics in synchrotron radiation and first principle calculations have revealed structural details of bonding transitions of crystalline earth materials at high pressure (Hemley 1998; Mao and Mao 2007; Price 2007; Stixrude 2007). The non-resonant synchrotron inelastic X-ray scattering (NRIXS, also known as X-ray Raman, XRS) is one of the relatively new synchrotron X-ray probes of local structures with element-specificity. It explores the electronic bonding transitions in soft X-ray absorption edges using hard X-rays (e.g., ~ 10 keV) …

Development of texture and seismic anisotropy during the onset of subduction

How reliable are shear wave splitting measurements as a means of determining mantle flow direction? This remains a topic of debate, especially in the context of subduction. The answer hinges on whether our current understanding of mineral physics provides enough to accurately translate between seismic observations and mantle deformation. Here, we present an integrated model to simulate strain‐history‐dependent texture development and estimate resulting shear wave splitting in subduction environments. We do this for a mantle flow model that, in its geometry, approximates the double‐sided Molucca Sea subduction system in Eastern Indonesia. We test a single‐sided and a double‐sided subduction case. Results are compared to recent splitting measurements of this region by Di Leo et al. (2012a). The setting lends itself as a case study, because it is fairly young and, therefore, early textures from the slab's descent from the near surface to the bottom of the mantle transition zone—which we simulate in our models—have not yet been overprinted by subsequent continuous steady state flow. Second, it allows us to test the significance of the double‐sided geometry, i.e., the need for a rear barrier to achieve trench‐parallel subslab mantle flow. We demonstrate that although a barrier amplifies trench‐parallel subslab anisotropy due to mantle flow, it is not necessary to produce trench‐parallel fast directions per se. In a simple model of A‐type olivine lattice‐preferred orientation and one‐sided subduction, trench‐parallel fast directions are produced by a combination of simple shear and extension through compression and pure shear in the subslab mantle.

NQR/NMR and Mössbauer spectroscopy of sulfides: potential and versatility

Nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and nuclear gamma-resonance (NGR or Mossbauer Effect) methods are generally described as highly sensitive tools in studies of local electronic structure and symmetry in solid-state materials. This is due to high informativity in electronic structure investigations, high resolution in phase-structural diagnostics (down to nano-scale), possibility to study polycrystalline and complex compounds, and to the non-destructive character of these methods. As applied to Earth sciences, both NQR/NMR and Mossbauer spectroscopy methods contribute to mineralogical material science and mineral physics. Another important aspect is the fact that these methods, as demonstrated recently, belong to unique techniques suitable for on-line bulk mineralogical analysis. This includes remotely operated sensors used with conveyor systems in mining/materials handling and similar applications where real-time data collection/processing provides significant commercial benefits. These developments open new pathways for NQR/NMR and Mossbauer spectroscopy applications. Notably, NQR/NMR and Mossbauer effects are observed primarily on different nuclei-probes but provide similar information about the local properties of materials (hyperfine fields, electric field gradients and relaxation effects). This makes NQR/NMR and Mossbauer methods mutually complementary despite their significant technical differences. This paper includes examples of recent applications of NQR, NMR and Mossbauer spectroscopic tools to studies of copper-, antimony- and iron-containing sulfides, demonstrating how these methods can contribute to an improved understanding of geochemical problems.

Estimating the electrical conductivity of the melt phase of a partially molten asthenosphere from seafloor magnetotelluric sounding data

Seafloor magnetotelluric soundings provide models of electrical conductivity distributions in the Earth’s oceanic mantle. By inverting the sounding results, a high-conductivity (typically 0.01–0.1S/m) layer is often obtained in the oceanic upper mantle, which is referred to as the electrical asthenosphere. The obtained high conductivity is then interpreted in terms of the amount of additional conduction that accounts for the conductivity value based on a physical model of the asthenosphere. There are two major candidates that are considered as the cause of the asthenosphere: the effect of water and partial melting. In this paper, we consider the partial melting hypothesis. We propose a method to estimate the electrical conductivity of the melt phase that is responsible for high conductivity by assuming the melt fraction distribution in the asthenosphere. We applied this method to one-dimensional conductivity profiles recently obtained from three regions of different seafloor age, and the results indicate that the proposed approach, combined with other approaches such as seismology and mineral physics, will provide useful information in testing a partial melting hypothesis for the cause of the asthenosphere.