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Sample records for olivines limnpo4 lifepo4

  1. Dynamic solubility limits in nanosized olivine LiFePO4.

    PubMed

    Wagemaker, Marnix; Singh, Deepak P; Borghols, Wouter J H; Lafont, Ugo; Haverkate, Lucas; Peterson, Vanessa K; Mulder, Fokko M

    2011-07-01

    Because of its stability, nanosized olivine LiFePO(4) opens the door toward high-power Li-ion battery technology for large-scale applications as required for plug-in hybrid vehicles. Here, we reveal that the thermodynamics of first-order phase transitions in nanoinsertion materials is distinctly different from bulk materials as demonstrated by the decreasing miscibility gap that appears to be strongly dependent on the overall composition in LiFePO(4). In contrast to our common thermodynamic knowledge, that dictates solubility limits to be independent of the overall composition, combined neutron and X-ray diffraction reveals strongly varying solubility limits below particle sizes of 35 nm. A rationale is found based on modeling of the diffuse interface. Size confinement of the lithium concentration gradient, which exists at the phase boundary, competes with the in bulk energetically favorable compositions. Consequently, temperature and size diagrams of nanomaterials require complete reconsideration, being strongly dependent on the overall composition. This is vital knowledge for the future nanoarchitecturing of superior energy storage devices as the performance will heavily depend on the disclosed nanoionic properties. PMID:21598941

  2. Enhancing the electrochemical kinetics of high voltage olivine LiMnPO4 by isovalent co-doping.

    PubMed

    Ramar, Vishwanathan; Balaya, Palani

    2013-10-28

    We report here doping of Fe(2+) and/or Mg(2+) in LiMnPO4 cathode material to enhance its lithium storage performance and appraise the effect of doping. For this purpose, LiMn0.9Fe(0.1-x)MgxPO4/C (x = 0 and 0.05) and LiMn0.95Mg0.05PO4/C have been prepared by a ball mill assisted soft template method. These materials were prepared with similar morphology, particle size and carbon content. Amongst them, the isovalent co-doped LiMn0.9Fe0.05Mg0.05PO4/C sample shows better electrochemical performance compared to LiMn0.9Fe0.1PO4/C and LiMn0.95Mg0.05PO4/C samples. For instance, a lithium storage capacity of 159 mA h g(-1) is obtained at 0.1 C for LiMn0.9Fe0.05Mg0.05PO4/C material with a relatively low polarization of ~139 mV. This is in sharp contrast to LiMn0.9Fe0.1PO4/C and LiMn0.95Mg0.05PO4/C which show only 136.8 and 128.4 mA h g(-1) at 0.1 C with the polarization of ~222 and 334 mV respectively. Further, the LiMn0.9Fe0.05Mg0.05PO4/C electrode delivers discharge capacities of 155.8, 141.4, 118.8, 104.6, 81.4 and 51.8 mA h g(-1) at 0.2, 0.5, 1, 2, 5 and 10 C respectively. This electrode material also retains a capacity of 116 mA h g(-1) at 1 C after 200 cycles, which is 96% of its initial capacity. Such improved cycling stability of LiMn0.9Fe0.05Mg0.05PO4/C is attributed to the suppressed Mn dissolution in the electrolyte compared to the other samples. Further, during the Li extraction process, delithiated phases created from the Fe(2+)/Fe(3+) redox reaction (~3.45 V) favor enhanced electrochemical activity of the succeeding Mn(2+)/Mn(3+) redox couples. The fully charged state (4.6 V) contains a partially lithiated phase owing to the presence of electrochemically inactive Mg(2+). The presence of such lithiated phase provides a favourable environment for the subsequent lithium insertion process. We also observe improved electronic conductivity and Li-ion diffusion for the co-doped sample compared to LiMnPO4 doped with either Fe(2+) or Mg(2+) by impedance measurements. The improved storage performance of co-doped LiMnPO4 is thus explained in terms of (i) favorable extraction and insertion reactions and (ii) enhanced transport properties. PMID:24018895

  3. Synthesis of Highly Crystalline Olivine-Type LiFePO4 Nanoparticles by Solution-Based Reactions

    NASA Astrophysics Data System (ADS)

    Kim, Donghan; Lim, Jinsub; Choi, Eunseok; Gim, Jihyeon; Mathew, Vinod; Paik, Younkee; Jung, Hongryun; Lee, Wanjin; Ahn, Docheon; Paek, Seungmin; Kim, Jaekook

    LiFePO4 nanocrystals were synthesized in various polyol media without any further post-heat treatment. The LiFePO4 samples synthesized using three different polyol media namely, diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TTEG), exhibited plate and rod-shaped structures with average sizes of 50-500 nm. The X-ray diffraction (XRD) patterns were indexed on the basis of an olivine structure (space group: Pnma). The samples prepared in DEG, TEG, and TTEG polyol media showed reversible capacities of 123, 155, and 166 mAh/g, respectively, at current density of 0.1 mA/cm2 with no capacity fading and exhibited excellent capacity retention up to the 50th cycle. In particular, the samples showed excellent performances at high rates of 30 and 60 C with high capacity retention. It is assumed that the nanometer size materials (~50 nm) possessing a highly crystalline nature may generate improved performance at high rate current densities.

  4. High-performance, nanostructure LiMnPO4/C composites synthesized via one-step solid state reaction

    NASA Astrophysics Data System (ADS)

    Zheng, Jugong; Ni, Liang; Lu, Yanwen; Qin, Cancan; Liu, Panxing; Wu, Tongfu; Tang, Yuefeng; Chen, Yanfeng

    2015-05-01

    LiMnPO4 is proposed as more promising cathode material as LiFePO4, while poor electronic conductivity and Jahn-Teller effects during charge/discharge processes hinder the electrochemical performance. To overcome these problems, one-step solid state reaction method is developed to synthesize LiMnPO4/C composites, which is with nanostructure, high crystallinity and good carbon coating. Manganese oxide sources and calcination temperature are investigated as factors for preparing high-performance LiMnPO4/C for Li-ion batteries. The results show that the LiMnPO4/C composites prepared with mixed manganese oxide deliver a superior initial capacity of 153 mAh g-1 at 0.05 C and high rate performance with discharge capacities of 123 mAh g-1 at 1 C and 103 mAh g-1 at 2 C. And the LiMnPO4/C composites synthesized at 600 °C can retain 94% of the initial capacity after 200 cycles at 1 C, revealing a stable cycling stability. Therefore, one-step solid state reaction brings to light the synthesis of high performance LiMnPO4/C cathode materials and is suitable for large scale production.

  5. Enhanced thermal safety and high power performance of carbon-coated LiFePO4 olivine cathode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Zaghib, K.; Dubé, J.; Dallaire, A.; Galoustov, K.; Guerfi, A.; Ramanathan, M.; Benmayza, A.; Prakash, J.; Mauger, A.; Julien, C. M.

    2012-12-01

    The carbon-coated LiFePO4 Li-ion oxide cathode was studied for its electrochemical, thermal, and safety performance. This electrode exhibited a reversible capacity corresponding to more than 89% of the theoretical capacity when cycled between 2.5 and 4.0 V. Cylindrical 18,650 cells with carbon-coated LiFePO4 also showed good capacity retention at higher discharge rates up to 5C rate with 99.3% coulombic efficiency, implying that the carbon coating improves the electronic conductivity. Hybrid Pulse Power Characterization (HPPC) test performed on LiFePO4 18,650 cell indicated the suitability of this carbon-coated LiFePO4 for high power HEV applications. The heat generation during charge and discharge at 0.5C rate, studied using an Isothermal Microcalorimeter (IMC), indicated cell temperature is maintained in near ambient conditions in the absence of external cooling. Thermal studies were also investigated by Differential Scanning Calorimeter (DSC) and Accelerating Rate Calorimeter (ARC), which showed that LiFePO4 is safer, upon thermal and electrochemical abuse, than the commonly used lithium metal oxide cathodes with layered and spinel structures. Safety tests, such as nail penetration and crush test, were performed on LiFePO4 and LiCoO2 cathode based cells, to investigate on the safety hazards of the cells upon severe physical abuse and damage.

  6. Structural and Electrochemical Characterization of Pure LiFePO 4 and Nanocomposite C- LiFePO 4 Cathodes for Lithium Ion Rechargeable Batteries

    DOE PAGESBeta

    Kumar, Arun; Thomas, R.; Karan, N. K.; Saavedra-Arias, J. J.; Singh, M. K.; Majumder, S. B.; Tomar, M. S.; Katiyar, R. S.

    2009-01-01

    Pure lithium iron phosphate ( LiFePO 4 ) and carbon-coated LiFePO 4 (C- LiFePO 4 ) cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating on LiFePO 4 particles. Ex situ Raman spectrum of C- LiFePO 4 at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of more » LiFePO 4 and C- LiFePO 4 showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13?mAh/g for C/5, C/3, and C/2, respectively for LiFePO 4 where as in case of C- LiFePO 4 that were 163, 144, 118, and 70?mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure LiFePO 4 was 69% after 25 cycles where as that of C- LiFePO 4 was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating. « less

  7. Cycling stability and degradation mechanism of LiMnPO4 based electrodes

    NASA Astrophysics Data System (ADS)

    Moskon, J.; Pivko, M.; Jerman, I.; Tchernychova, E.; Logar, N. Zabukovec; Zorko, M.; Selih, V. S.; Dominko, R.; Gaberscek, M.

    2016-01-01

    Long term stability of LiMnPO4 particles with a crystallite size between ?20 and 50 nm covered with a dense native carbon coating (14 wt.%) is demonstrated. More than 500 cycles at a rate of C/20, in the potential window of 2.7-4.5 V and a temperature of 55 °C were achieved. During most of the cycling the average capacity decay was less than 0.06% per cycle. After about 500 cycles a sudden capacity drop was observed. Degradation processes in various stages of cycling were thoroughly examined using a range of techniques. Severe surface film formation, manganese dissolution and degradation of LixMnPO4 accompanied by formation of Li4P2O7 were clearly identified. The good long term stability seems to be due to dense, protective carbon coating. Decomposition is most likely initiated at local defects in the microstructure of pyrolytic carbon coating around LiMnPO4 particles. In addition to known degradation mechanisms of LiMnPO4 we observed pronounced gradual amorphization of the olivine crystallites during long-term cycling at 55 °C. Finally, changes in morphology of the carbon black additive after prolonged cycling are reported and commented.

  8. Hyperfine fields at the Li site in LiFePO(4)-type olivine materials for lithium rechargeable batteries: a (7)Li MAS NMR and SQUID study.

    PubMed

    Tucker, Michael C; Doeff, Marca M; Richardson, Thomas J; Fiñones, Rita; Cairns, Elton J; Reimer, Jeffrey A

    2002-04-17

    The (7)Li NMR isotropic shift for olivine LiMPO(4) (M = Fe, Mn, Co, Ni) is assigned to hyperfine coupling between the (7)Li nucleus and the transition metal unpaired electrons on the basis of the Curie-Weiss temperature dependence of the shift. The hyperfine shift arises from a linear combination of Li-O-M through-bond interactions wherein the unpaired A' electrons contribute a negative shift and the unpaired A' ' electrons contribute a positive shift. The hyperfine coupling constant is determined for each composition. PMID:11942811

  9. Tunable morphology synthesis of LiFePO4 nanoparticles as cathode materials for lithium ion batteries.

    PubMed

    Ma, Zhipeng; Shao, Guangjie; Fan, Yuqian; Wang, Guiling; Song, Jianjun; Liu, Tingting

    2014-06-25

    Olivine LiFePO4 with nanoplate, rectangular prism nanorod and hexagonal prism nanorod morphologies with a short b-axis were successfully synthesized by a solvothermal in glycerol and water system. The influences of solvent composition on the morphological transformation and electrochemical performances of olivine LiFePO4 are systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and galvanostatic charge-discharge tests. It is found that with increasing water content in solvent, the LiFePO4 nanoplates gradually transform into hexagonal prism nanorods that are similar to the thermodynamic equilibrium shape of the LiFePO4 crystal. This indicates that water plays an important role in the morphology transformation of the olivine LiFePO4. The electrochemical performances vary significantly with the particle morphology. The LiFePO4 rectangular prism nanorods (formed in a glycerol-to-water ratio of 1:1) exhibit superior electrochemical properties compared with the other morphological particles because of their moderate size and shorter Li(+) ion diffusion length along the [010] direction. The initial discharge capacity of the LiFePO4@C with a rectangular prism nanorod morphology reaches to 163.8 mAh g(-1) at 0.2 C and over 75 mAh g(-1) at the high discharging rate of 20 C, maintaining good stability at each discharging rate. PMID:24892948

  10. Low-temperature synthesis of LiFePO4 nanocrystals by solvothermal route

    PubMed Central

    2012-01-01

    LiFePO4 nanocrystals were synthesized at a very low temperature of 170°C using carbon nanoparticles by a solvothermal process in a polyol medium, namely diethylene glycol without any heat treatment as a post procedure. The powder X-ray diffraction pattern of the LiFePO4 was indexed well to a pure orthorhombic system of olivine structure (space group: Pnma) with no undesirable impurities. The LiFePO4 nanocrystals synthesized at low temperature exhibited mono-dispersed and carbon-mixed plate-type LiFePO4 nanoparticles with average length, width, and thickness of approximately 100 to 300 nm, 100 to 200 nm, and 50 nm, respectively. It also appeared to reveal considerably enhanced electrochemical properties when compared to those of pristine LiFePO4. These observed results clearly indicate the effect of carbon in improving the reactivity and synthesis of LiFePO4 nanoparticles at a significantly lower temperature. PMID:22222099

  11. Low-temperature synthesis of LiFePO4 nanocrystals by solvothermal route

    NASA Astrophysics Data System (ADS)

    Lim, Jinsub; Kang, Sung-Won; Moon, Jieh; Kim, Sungjin; Park, Hyosun; Baboo, Joseph Paul; Kim, Jaekook

    2012-01-01

    LiFePO4 nanocrystals were synthesized at a very low temperature of 170°C using carbon nanoparticles by a solvothermal process in a polyol medium, namely diethylene glycol without any heat treatment as a post procedure. The powder X-ray diffraction pattern of the LiFePO4 was indexed well to a pure orthorhombic system of olivine structure (space group: Pnma) with no undesirable impurities. The LiFePO4 nanocrystals synthesized at low temperature exhibited mono-dispersed and carbon-mixed plate-type LiFePO4 nanoparticles with average length, width, and thickness of approximately 100 to 300 nm, 100 to 200 nm, and 50 nm, respectively. It also appeared to reveal considerably enhanced electrochemical properties when compared to those of pristine LiFePO4. These observed results clearly indicate the effect of carbon in improving the reactivity and synthesis of LiFePO4 nanoparticles at a significantly lower temperature.

  12. Electrical conductivity studies of graphene wrapped nanocrystalline LiMnPO4 composite

    NASA Astrophysics Data System (ADS)

    Cheruku, Rajesh; D, Surya Bhaskaram; Govindaraj, G.; Vijayan, Lakshmi

    2015-06-01

    Nanocrystalline LiMnPO4 material was synthesized by template free sucrose assisted hydrothermal method. The material possesses the orthorhombic crystal structure with Pnma, space group having four formula units. The GO was prepared by the hummer's method and it was reduced graphene oxide (rGO) with hydrazine hydrate in the presence of nitrogen atmosphere. LiMnPO4 material was wrapped by the rGO to increase its conductivity. The structural characterization was accomplished through X-ray diffraction, FT-IR and Raman spectroscopy. Morphology was identified by the SEM, Electrical characterization was done through impedance spectroscopy and the results were reported.

  13. Synthesis of a LiFePO4/C cathode material by using a high-energy nano mill

    NASA Astrophysics Data System (ADS)

    Islam, Mobinul; Yoon, Man-Soon; Ur, Soon-Chul

    2015-07-01

    Olivine lithium iron phosphate (LiFePO4) is a promising cathode material for Li-ion battery. A temperature around 700 - 800 ? is generally required to prepare LiFePO4 powder with good crystallinity. The LiFePO4 materials are synthesized via a solid-state method by using a highenergy nano mill (HENM). The conventional ball-milling process is also conducted for the same material for a comparative study. The effect of the precursor's mixing processes on the synthesis temperature of LiFePO4 is investigated in this study. The required reaction temperature of LiFePO4 is 432 ? for the HENM process and 480 ? for the ball-mill process as found from the differential scanning calorimetry (DSC) results. The HENM process improves the reaction activity and the homogeneity of the materials used throughout process and lowers the reaction temperature as compared with the conventional ball-mill process. The milled powders are characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sample synthesized by using the HENM process exhibits a discharge capacity of 136 mAhg -1 at 0.1 C rate. The results in this study indicate that the HENM process is a substantial and promising process for LiFePO4 cathode preparation owing to its short fabrication time and ability to improve the reaction condition. A HENM can be used to promote formation of LiFePO4 at lower temperatures.

  14. Rapid Polyol-Assisted Microwave Synthesis of Nanocrystalline LiFePO4/C Cathode for Lithium-Ion Batteries.

    PubMed

    Paul, Baboo Joseph; Gim, Jihyeon; Baek, Sora; Kang, Jungwon; Song, Jinju; Kim, Sungjin; Kim, Jaekook

    2015-08-01

    Nanocrystalline LiFePO4/C has been synthesized under a very short period of time (90 sec) using a polyol-assisted microwave heating synthesis technique. The X-ray diffraction (XRD) data indicates that the rapidly synthesized materials correspond to phase pure olivine. Post-annealing of the as-prepared sample at 600 °C in argon atmosphere yields highly crystalline LiFePO4/C. The morphology of the samples studied using scanning electron microscopy (SEM) reveals the presence of secondary particles formed from aggregation of primary particles in the range of 30-50 nm. Transmission electron microscopy (TEM) images reveal a thin carbon layer coating on the surface of the primary particle. The charge/discharge studies indicate that the as-prepared and annealed LiFePO4/C samples delivered initial discharge capacities of 126 and 160 mA h g-1, respectively, with good capacity retentions at 0.05 mA cm-2 current densities. The post-annealing process indeed improves the crystallinity of the LiFePO4 nanocrystals, which enhances the electrode performance of LiFePO4/C. PMID:26369219

  15. Reaction mechanism and influence of the experimental variables for solvothermal synthesized LiMnPO4 nanoplates

    NASA Astrophysics Data System (ADS)

    Zhu, Kunlei; Zhang, Wenxuan; Du, Jiangyong; Liu, Xiaoyan; Tian, Jianhua; Ma, Huanmei; Liu, Shengzhong; Shan, Zhongqiang

    2015-12-01

    Plate-like LiMnPO4 nanomaterial for Li-ion batteries is synthesised successfully via a facile solvothermal process in mixed water-diethylene glycol (DEG) solvents at 190 °C for 3 h. Experimental variables, including reaction time, reaction temperature and reactant mole ratio, are discussed in detail. A tentative reaction mechanism is proposed on the basis of the time dependent trials. It is found that, with the increase of reaction temperature, the formation of LiMnPO4 phase is accelerated and the reaction for synthesizing LiMnPO4 can be finished in a shorter time. Studies on the effect of reactant mole ratio further support the proposed mechanism. The electrochemical properties of obtained LiMnPO4 are examined after a carbon coating process. Electrochemical tests show that the obtained LiMnPO4 at 190 °C for 3 h exhibits better electrochemical performances than the LiMnPO4 synthesized at 170 °C for 4.5 h or 150 °C for 6 h. It is clear that an improved electrochemical performance can be obtained with the increase of reaction temperature and the decrease of reaction time. This result provides us thoughts and guidance to optimize the reaction conditions by harmonizing the reaction temperature and reaction time, which is beneficial for the practical application.

  16. Temperature Dependence of Aliovalent-vanadium Doping in LiFePO4 Cathodes

    SciTech Connect

    Harrison, Katharine L; Bridges, Craig A; Paranthaman, Mariappan Parans; Idrobo Tapia, Juan C; Manthiram, Arumugam; Goodenough, J. B.; Segre, C; Katsoudas, John; Maroni, V. A.

    2013-01-01

    Vanadium-doped olivine LiFePO4 cathode materials have been synthesized by a novel low-temperature microwave-assisted solvothermal (MW-ST) method at 300 oC. Based on chemical and powder neutron/X-ray diffraction analysis, the compositions of the synthesized materials were found to be LiFe1-3x/2Vx x/2PO4 (0 x 0.2) with the presence of a small number of lithium vacancies charge-compensated by V4+, not Fe3+, leading to an average oxidation state of ~ 3.2+ for vanadium. Heating the pristine 15 % V-doped sample in inert or reducing atmospheres led to a loss of vanadium from the olivine lattice with the concomitant formation of a Li3V2(PO4)3 impurity phase; after phase segregation, a partially V-doped olivine phase remained. For comparison, V-doped samples were also synthesized by conventional ball milling and heating, but only ~ 10 % V could be accommodated in the olivine lattice in agreement with previous studies. The higher degree of doping realized with the MW-ST samples demonstrates the temperature dependence of the aliovalent-vanadium doping in LiFePO4.

  17. A polyethylene glycol-assisted carbothermal reduction method to synthesize LiFePO4 using industrial raw materials

    NASA Astrophysics Data System (ADS)

    Fey, George Ting-Kuo; Huang, Kai-Pin; Kao, Hsien-Ming; Li, Wen-Hsien

    2011-03-01

    Olivine LiFePO4 is synthesized by a carbothermal reduction method (CTR) using industrial raw materials with polyethylene glycol (PEG) as a reductive agent and carbon source. A required amount of acetone is added to the starting materials for the ball milling process and the precursor is sintered at 973 K for 8 h to form crystalline phase LiFePO4. The structure and morphology of the LiFePO4/C composite samples have been characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, differential scanning calorimetry and magnetic susceptibility. Electrochemical measurements show that the LiFePO4/C composite cathode delivers an initial discharge capacity of 150 mAh g-1 at a 0.2C-rate between 4.0 and 2.8 V, and almost no capacity loss is observed for up to 50 cycles. Remarkably, the cell can sustain a 30C-rate between 4.6 and 2.0 V, and this rate capability is equivalent to charge or discharge in 2 min. The simple technique, low-cost starting materials, and excellent electrochemical performance make this process easier to commercialize than other synthesized methods.

  18. Effects of Ag-embedment on electronic and ionic conductivities of LiMnPO4 and its performance as a cathode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Kug-Seung; Lee, Kyung Jae; Kang, Yun Sik; Shin, Tae Joo; Sung, Yung-Eun; Ahn, Docheon

    2015-08-01

    An Ag-embedded LiMnPO4 (LMP) cathode was synthesized by solid-state reaction using a 1 wt% Ag precursor. Structure, morphology, and electrical conductivity studies of Ag-embedded LMP were performed by high resolution powder X-ray diffraction, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and four probe measurements. An Ag nanoparticle (~26 nm) surrounded by several olivine crystallites within a single particle dramatically improved the overall electrical conductivity of LMP by four orders of magnitude relative to that of pristine LMP, playing roles as conducting bridges among LMP crystallites as well as particles. Rietveld analysis confirmed structural variations related to the modification of atomic bond lengths of Mn-O, P-O, and Li-O coordination due to Ag-embedment and thereby leads to facile Li ion diffusion in LMP. Consequently, although a small amount of Ag was included, the Ag-embedded LMP cathode exhibited outstanding electrochemical performances (92 mA h g-1 at 10 C) versus lithium.An Ag-embedded LiMnPO4 (LMP) cathode was synthesized by solid-state reaction using a 1 wt% Ag precursor. Structure, morphology, and electrical conductivity studies of Ag-embedded LMP were performed by high resolution powder X-ray diffraction, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and four probe measurements. An Ag nanoparticle (~26 nm) surrounded by several olivine crystallites within a single particle dramatically improved the overall electrical conductivity of LMP by four orders of magnitude relative to that of pristine LMP, playing roles as conducting bridges among LMP crystallites as well as particles. Rietveld analysis confirmed structural variations related to the modification of atomic bond lengths of Mn-O, P-O, and Li-O coordination due to Ag-embedment and thereby leads to facile Li ion diffusion in LMP. Consequently, although a small amount of Ag was included, the Ag-embedded LMP cathode exhibited outstanding electrochemical performances (92 mA h g-1 at 10 C) versus lithium. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00933b

  19. Effects of Ag-embedment on electronic and ionic conductivities of LiMnPO4 and its performance as a cathode for lithium-ion batteries.

    PubMed

    Lee, Kug-Seung; Lee, Kyung Jae; Kang, Yun Sik; Shin, Tae Joo; Sung, Yung-Eun; Ahn, Docheon

    2015-09-01

    An Ag-embedded LiMnPO4 (LMP) cathode was synthesized by solid-state reaction using a 1 wt% Ag precursor. Structure, morphology, and electrical conductivity studies of Ag-embedded LMP were performed by high resolution powder X-ray diffraction, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and four probe measurements. An Ag nanoparticle (?26 nm) surrounded by several olivine crystallites within a single particle dramatically improved the overall electrical conductivity of LMP by four orders of magnitude relative to that of pristine LMP, playing roles as conducting bridges among LMP crystallites as well as particles. Rietveld analysis confirmed structural variations related to the modification of atomic bond lengths of Mn-O, P-O, and Li-O coordination due to Ag-embedment and thereby leads to facile Li ion diffusion in LMP. Consequently, although a small amount of Ag was included, the Ag-embedded LMP cathode exhibited outstanding electrochemical performances (92 mA h g(-1) at 10 C) versus lithium. PMID:26186268

  20. Enhanced rate performance of LiFePO4/C by co-doping titanium and vanadium

    NASA Astrophysics Data System (ADS)

    Long, Yun-Fei; Su, Jing; Cui, Xiao-Ru; Lv, Xiao-Yan; Wen, Yan-Xuan

    2015-10-01

    V and Ti co-doped LiFePO4/C composites were synthesized by a wet milling assisted carbothermal reduction technology. The structure, morphology and electrochemical performance of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), magnetic susceptibility, positron annihilation lifetime spectra (PAS), scanning electron microscope (SEM), charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV). The results showed that the V and Ti co-doped samples kept the olivine structure of LiFePO4, but the synergistic effects between V3+ and Ti4+ in the lattice can increase the disorder degree of the lattice and create Li+ vacancies in LiFePO4/C, thus improve electronic conductivity and Li+ diffusion coefficient. LiV0.069Ti0.025Fe0.905PO4/C delivers an initial discharge capacity of 144.1 mAh g-1 with a capacity retention ratio of 99.4%, 96.3% and 93.6% after 100, 200 and 300 cycles at 10C, respectively. Remarkably, it still gives a high discharge capacity of 124.8 mAh g-1 even at a high rate of 20C.

  1. Synthesis, non-isothermal kinetic and thermodynamic studies of the formation of LiMnPO4 from NH4MnPO4·H2O precursor

    NASA Astrophysics Data System (ADS)

    Sronsri, Chuchai; Noisong, Pittayagorn; Danvirutai, Chanaiporn

    2014-06-01

    NH4MnPO4·H2O was successfully synthesized by precipitating method. The LiMnPO4 was successfully generated through solid state reaction between synthesized NH4MnPO4·H2O precursor and Li2CO3. The morphologies were observed to depend on the reaction temperatures. The thermal decomposition of NH4MnPO4·H2O and the formation process of LiMnPO4 were confirmed by TG/DTG/DTA, FTIR, AAS/AES, XRD and SEM methods. The average crystallite size of NH4MnPO4·H2O, Mn2P2O7 and LiMnPO4 were found to be around 51.2, 44.9 and 48.1 nm, respectively. The non-isothermal kinetic parameters (kinetic triplet: E?, A, g(?)) of the formation process of LiMnPO4 were evaluated from TG data by using Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods. The iterative methods of both equations were carried out to determine the exact values of E?. The Coats-Redfern equation and kinetic compensation effects were successfully applied to confirm the activation energy and the most probable mechanism functions of the formation of LiMnPO4. The thermodynamic functions (?H?, ?S?, ?G?) of the transition state complexes of the formation of LiMnPO4 were calculated from the kinetic parameters for the first time.

  2. The influence of improved carbon coating layer with nanometer-sized CeO2 interconnector on the enhanced electrochemical performance of LiMnPO4

    NASA Astrophysics Data System (ADS)

    Chen, Fang-Jie; Tao, Fen; Wang, Chun-Mei; Zhang, Wen-Long; Chen, Li

    2015-07-01

    The CeO2/C hybrid coated LiMnPO4 composites are prepared via a simple and effective wet chemical process followed by heat treatment at 550 °C. The nanometer-sized CeO2 acts as an interconnector in carbon network, and its influence on the electrochemical performance is investigated in detail. The 0.25 wt.% CeO2-modified LiMnPO4/C (sample-0.25) exhibits the highest discharge capacity and the best cycle life, which can deliver an initial capacity of 139.9 mAh g-1 at 0.1C and still retain a reversible capacity of 120.4 mAh g-1 after 50 cycles (capacity retention of 86.1%). While for pristine LiMnPO4/C (sample-0), only 94.4 mAh g-1 can be obtained at the 50th cycle, corresponding to 72.9% of its initial discharge capacity (129.5 mAh g-1). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) results confirm that an integrated and hybrid CeO2/C coating layer is formed on LiMnPO4 surface and its existence has no influence on the structure of LiMnPO4. The reason for the improved electrochemical properties of the CeO2-modified LiMnPO4/C composites has also been studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements.

  3. Lithium-Ion Insertion Kinetics of Na-Doped LiFePO4 as Cathode Materials for Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Yan-Rong; Zhang, Rui; Deng, Li; Yi, Ting-Feng; Ye, Ming-Fu; Yao, Jin-Han; Dai, Chang-Song

    2015-03-01

    Na-doped Li1- x Na x FePO4 ( x = 0, 0.05, 0.1, and 0.2) materials were synthesized by a simple high-temperature solid-state method. The structure, morphology, and kinetic performances of the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). XRD indicates that all samples are in accordance with the standard LiFePO4 with olivine structure. SEM reveals that the particle size of all samples is about 1 to 2 µm. CV exhibits that Na doping obviously improves the reversibility and dynamic behaviors of lithium intercalation and deintercalation. EIS shows that Na doping decreases the charge transfer resistance of LiFePO4 and improves the lithium diffusion coefficients. It can be concluded that Na doping results in lower electrode polarization and higher lithium-ion diffusion coefficient, which can effectively improve the kinetic performance of LiFePO4.

  4. Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X. S.

    2013-12-01

    In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04611g

  5. Comparison of LiFePO4 from different sources

    SciTech Connect

    Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat; Newman, John

    2003-11-25

    The lithium iron phosphate chemistry is plagued by the poor conductivity and slow lithium diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study we obtained LiFePO4 electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from one with no carbon coating to one with 15 percent coating. In addition, particle sizes varied by as much as a order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of dopant on performance and ideas for making materials in order to maximize the power capability of this chemistry.

  6. Probing the failure mechanism of nanoscale LiFePO4 for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Gu, Meng; Shi, Wei; Zheng, Jianming; Yan, Pengfei; Zhang, Ji-guang; Wang, Chongmin

    2015-05-01

    LiFePO4 is a high power rate cathode material for lithium ion battery and shows remarkable capacity retention, featuring a 91% capacity retention after 3300 cycles. In this work, we use high-resolution transmission electron microscopy and electron energy loss spectroscopy to study the gradual capacity fading mechanism of LiFePO4 materials. We found that upon prolonged electrochemical cycling of the battery, the LiFePO4 cathode shows surface amorphization and loss of oxygen species, which directly contribute to the gradual capacity fading of the battery. The finding can guide the design and improvement of LiFePO4 cathode for high-energy and high-power rechargeable battery for electric transportation.

  7. Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

    NASA Astrophysics Data System (ADS)

    Muruganantham, R.; Sivakumar, M.; Subadevi, R.

    2015-12-01

    Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ?100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g-1 at C/10. Also, it exhibits 89 mAh g-1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

  8. Unlocking the energy capabilities of micron-sized LiFePO4

    NASA Astrophysics Data System (ADS)

    Guo, Limin; Zhang, Yelong; Wang, Jiawei; Ma, Lipo; Ma, Shunchao; Zhang, Yantao; Wang, Erkang; Bi, Yujing; Wang, Deyu; McKee, William C.; Xu, Ye; Chen, Jitao; Zhang, Qinghua; Nan, Cewen; Gu, Lin; Bruce, Peter G.; Peng, Zhangquan

    2015-08-01

    Utilization of LiFePO4 as a cathode material for Li-ion batteries often requires size nanonization coupled with calcination-based carbon coating to improve its electrochemical performance, which, however, is usually at the expense of tap density and may be environmentally problematic. Here we report the utilization of micron-sized LiFePO4, which has a higher tap density than its nano-sized siblings, by forming a conducting polymer coating on its surface with a greener diazonium chemistry. Specifically, micron-sized LiFePO4 particles have been uniformly coated with a thin polyphenylene film via the spontaneous reaction between LiFePO4 and an aromatic diazonium salt of benzenediazonium tetrafluoroborate. The coated micron-sized LiFePO4, compared with its pristine counterpart, has shown improved electrical conductivity, high rate capability and excellent cyclability when used as a `carbon additive free' cathode material for rechargeable Li-ion batteries. The bonding mechanism of polyphenylene to LiFePO4/FePO4 has been understood with density functional theory calculations.

  9. Enhanced electrochemical performances of LiFePO4/C by surface modification with Sn nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Yingbin; Lin, Ying; Zhou, Ting; Zhao, Guiying; Huang, Yandan; Huang, Zhigao

    2013-03-01

    The surface of LiFePO4/C cathode material is coated with nano-sized Sn via a simple electroless deposition (ED) process, and the effects of the Sn-coating on the electrochemical performances of LiFePO4/C are investigated systematically by the charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. In comparison with the pristine LiFePO4/C, the Sn-coated LiFePO4/C exhibits higher capacity, better cyclability and higher rate capability in a wide operation temperature range. An analysis of the electrochemical measurements reveals that Sn-coated LiFePO4/C has good electric contact among particles, much lower charge-transfer resistances and higher lithium diffusion rate, especially at low temperature. In addition, the Sn-coating layer protects the active materials from chemical attack by HF and thus suppresses the dissolution of Fe from LiFePO4 in the LiPF6 based electrolyte.

  10. Unlocking the energy capabilities of micron-sized LiFePO4

    PubMed Central

    Guo, Limin; Zhang, Yelong; Wang, Jiawei; Ma, Lipo; Ma, Shunchao; Zhang, Yantao; Wang, Erkang; Bi, Yujing; Wang, Deyu; McKee, William C.; Xu, Ye; Chen, Jitao; Zhang, Qinghua; Nan, Cewen; Gu, Lin; Bruce, Peter G.; Peng, Zhangquan

    2015-01-01

    Utilization of LiFePO4 as a cathode material for Li-ion batteries often requires size nanonization coupled with calcination-based carbon coating to improve its electrochemical performance, which, however, is usually at the expense of tap density and may be environmentally problematic. Here we report the utilization of micron-sized LiFePO4, which has a higher tap density than its nano-sized siblings, by forming a conducting polymer coating on its surface with a greener diazonium chemistry. Specifically, micron-sized LiFePO4 particles have been uniformly coated with a thin polyphenylene film via the spontaneous reaction between LiFePO4 and an aromatic diazonium salt of benzenediazonium tetrafluoroborate. The coated micron-sized LiFePO4, compared with its pristine counterpart, has shown improved electrical conductivity, high rate capability and excellent cyclability when used as a ‘carbon additive free' cathode material for rechargeable Li-ion batteries. The bonding mechanism of polyphenylene to LiFePO4/FePO4 has been understood with density functional theory calculations. PMID:26235395

  11. Impacts of different polymer binders on electrochemical properties of LiFePO4 cathode

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Hiep; Wang, Wan Lin; Jin, En Mei; Gu, Hal-Bon

    2013-10-01

    Impacts of different polymer binders (PVdF, PAA and PMMA) on electrochemical performance of the LiFePO4 cathode in Li-ion batteries are investigated. From CV result, the voltage between redox peaks of the LiFePO4 with PVdF, PAA and PMMA binders are 0.26, 0.20 and 0.23 V, respectively. The current of the LiFePO4 with PMMA binder shows the highest value of 1.4 mA. The apparent diffusion coefficient of the LiFePO4 with PVdF, PAA and PMMA binders is 8.30 × 10-12, 2.57 × 10-11 and 9.13 × 10-11 cm2 s-1, respectively. The discharge capacities of the LiFePO4 with PVdF, PAA and PMMA binders are 106, 143 and 154 mAh g-1 at an initial cycle, respectively. FE-SEM studies clearly demonstrate that plate-like PAA and PMMA coating on the electrodes form a protective film, which may decrease the amount of the deposits, thus decreasing crack and crystallization on the electrode surface. Achieved results indicate that PVdF, PAA and PMMA binders show better properties than the traditional one, especially PMMA one.

  12. Dynamic study of sub-micro sized LiFePO4 cathodes by in-situ tender X-ray absorption near edge structure

    NASA Astrophysics Data System (ADS)

    Wang, Dongniu; Wang, Huixin; Yang, Jinli; Zhou, Jigang; Hu, Yongfeng; Xiao, Qunfeng; Fang, Haitao; Sham, Tsun-Kong

    2016-01-01

    Olivine-type phosphates (LiMPO4, M = Fe, Mn, Co) are promising cathode materials for lithium-ion batteries that are generally accepted to follow first order equilibrium phase transformations. Herein, the phase transformation dynamics of sub-micro sized LiFePO4 particles with limited rate capability at a low current density of 0.14 C was investigated. An in-situ X-ray Absorption Near Edge Structure (XANES) measurement was conducted at the Fe and P K-edge for the dynamic studies upon lithiation and delithiation. Fe K-edge XANES spectra demonstrate that not only lithium-rich intermediate phase LixFePO4 (x = 0.6-0.75), but also lithium-poor intermediate phase LiyFePO4 (y = 0.1-0.25) exist during the charge and discharge, respectively. Furthermore, during charge and discharge, a fluctuation of the FePO4 and LiFePO4 fractions obtained by liner combination fitting around the imaginary phase fractions followed Faraday's law and the equilibrium first-order two-phase transformation versus reaction time is present, respectively. The charging and discharging process has a reversible phase transformation dynamics with symmetric structural evolution routes. P K-edge XANES spectra reveal an enrichment of PF6-1 anions at the surface of the electrode during charging.

  13. Synthesis and characterization of LiFePO4 cathode preparation by low temperature method

    NASA Astrophysics Data System (ADS)

    Rajesh, Desapogu; Srinivas Naik, V.; Sunandana, C. S.

    2015-05-01

    We review in detail the physics and technology of the novel material LiFePO4, a potential cathode material for Li-ion batteries. In the present work, nano crystalline LiFePO4 film has been synthesized in both powder and thin film forms from a non-aqueous sol-gel synthesis route based on oxalates of Li and Fe (II). Ferrous oxalate has been synthesized indigenously using a ferrous sulphate based chemical reaction and characterized. Nano powders and thin films of LiFePO4 have been fabricated and coated on stainless steel substrates with the aim of device development in future. The material has been characterized extensively by XRD for crystal structure, FESEM for microstructure, EDS for elemental analysis and FTIR for the internal modes of phosphate ion. Fe3+ impurity characterization has been done by using ESR.

  14. Carbon Surface Layers on a High-Rate LiFePO4

    SciTech Connect

    Gabrisch, Heike; Wilcox, James D.; Doeff, Marca M.

    2005-09-06

    Transmission electron microscopy (TEM) was used to image particles of a high-rate LiFePO4 sample containing a small amount of in situ carbon. The particle morphology is highly irregular, with a wide size distribution. Nevertheless, coatings, varying from about 5-10 nm in thickness, could readily be detected on surfaces of particles as well as on edges of agglomerates. Elemental mapping using Energy Filtered TEM (EFTEM) indicates that these very thin surface layers are composed of carbon. These observations have important implications for the design of high-rate LiFePO4 materials in which, ideally, a minimal amount of carbon coating is used.

  15. Conductive surface modification of LiFePO4 with nitrogen doped carbon layers for lithium-ion batteries

    SciTech Connect

    Yoon, Sukeun; Liao, Chen; Sun, Xiao-Guang; Bridges, Craig A; Unocic, Raymond R; Nanda, Jagjit; Dai, Sheng; Paranthaman, Mariappan Parans

    2012-01-01

    The LiFePO4 rod surface modified with nitrogen doped carbon layer has been prepared using hydrothermal processing followed by post-annealing in the presence of an ionic liquid. The coated LiFePO4 rod exhibits good capacity retention and high rate capability as the nitrogen doped carbon improves conductivity and prevents aggregation of the rod during cycling.

  16. Hierarchical LiFePO4 with a controllable growth of the (010) facet for lithium-ion batteries

    PubMed Central

    Guo, Binbin; Ruan, Hongcheng; Zheng, Cheng; Fei, Hailong; Wei, Mingdeng

    2013-01-01

    Hierarchically structured LiFePO4 was successfully synthesized by ionic liquid solvothermal method. These hierarchically structured LiFePO4 samples were constructed from nanostructured platelets with their (010) facets mainly exposed. To the best of our knowledge, facet control of a hierarchical LiFePO4 crystal has not been reported yet. Based on a series of experimental results, a tentative mechanism for the formation of these hierarchical structures was proposed. After these hierarchically structured LiFePO4 samples were coated with a thin carbon layer and used as cathode materials for lithium-ion batteries, they exhibited excellent high-rate discharge capability and cycling stability. For instance, a capacity of 95% can be maintained for the LiFePO4 sample at a rate as high as 20 C, even after 1000 cycles. PMID:24071818

  17. Structural and Electrical Properties of Lithium-Ion Rechargeable Battery Using the LiFePO4/Carbon Cathode Material.

    PubMed

    Kim, Young-Sung; Jeoung, Tae-Hoon; Nam, Sung-Pill; Lee, Seung-Hwan; Kim, Jea-Chul; Lee, Sung-Gap

    2015-03-01

    LiFePO4/C composite powder as cathode material and graphite powder as anode material for Li-ion batteries were synthesized by using the sol-gel method. An electrochemical improvement of LiFePO4 materials has been achieved by adding polyvinyl alcohol as a carbon source into as-prepared materials. The samples were characterized by elemental analysis (EA), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-EM). The chemical composition of LiFePO4/C powders was in a good agreement with that of the starting solution. The capacity loss after 500 cycles of LiFePO4/C cell is 11.1% in room temperature. These superior electrochemical properties show that LiFePO4/C composite materials are promising candidates as cathode materials. PMID:26413683

  18. Thermal Stability and Phase Transformation of Electrochemically Charged/Discharged LiMnPO4 Cathode for Li-Ion Battery

    SciTech Connect

    Choi, Daiwon; Xiao, Jie; Choi, Young Joon; Hardy, John S.; Vijayakumar, M.; Bhuvaneswari, M. S.; Liu, Jun; Xu, Wu; Wang, Wei; Yang, Zhenguo; Graff, Gordon L.; Zhang, Jiguang

    2011-11-01

    Electrochemically active LiMnPO4 nanoplate at lithiated/delithiated state were subjected to thermal stability and phase transformation evaluate for safety as a cathode material for Li-ion battery. The phase transformation and oxygen evolution temperature on the delithiated MnPO4 were characterized using in-situ hot-stage X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), thermogravimetric - differential scanning calorimetry - mass spectroscopy (TGA-DSC-MS), transmission electron microscopy and scanning electron microscopy (SEM) - energy dispersive X-ray analysis (EDAX).

  19. LiFePO4 - 3D carbon nanofiber composites as cathode materials for Li-ions batteries

    NASA Astrophysics Data System (ADS)

    Dimesso, L.; Spanheimer, C.; Jaegermann, W.; Zhang, Y.; Yarin, A. L.

    2012-03-01

    The characterization of carbon nanofiber 3D nonwovens, prepared by electrospinning process, coated with olivine structured lithium iron phosphate is reported. The LiFePO4 as cathode material for lithium ion batteries was prepared by a Pechini-assisted reversed polyol process. The coating has been successfully performed on carbon nanofiber 3D nonwovens by soaking in aqueous solution containing lithium, iron salts and phosphates at 70 °C for 2-4 h. After drying-out, the composites were annealed at 600 °C for 5 h under nitrogen. The surface investigation of the prepared composites showed a uniform coating of the carbon nonwoven nanofibers as well as the formation of cauliflower-like crystalline structures which are uniformly distributed all over the surface area of the carbon nanofibers. The electrochemical measurements on the composites showed good performances delivering a discharge specific capacity of 156 mAhg- 1 at a discharging rate of C/25 and 152 mAhg- 1 at a discharging rate of C/10 at room temperature.

  20. Electrical relaxation studies of olivine type nanocrystalline LiMPO4 (M=Ni, Mn and Co) materials

    NASA Astrophysics Data System (ADS)

    Cheruku, Rajesh; Kruthika, G.; Govindaraj, G.; Vijayan, Lakshmi

    2015-11-01

    The olivine type LiMPO4 (M=Ni, Mn and Co) materials were synthesized by solution combustion technique using glycine as fuel. The structural characterizations were explored to confirm the phase formation of materials. The scanning electron microscope was used to identify the morphology of olivine materials. The local structure and chemical bonding between MO6 octahedral and (PO4)3- tetrahedral groups were probed by Raman spectroscopy. Grain and grain boundaries were contributed for ion relaxation and dc conduction in olivine materials. Two orders of enhancement in ionic conductivity was observed in these olivine materials than the reported value. Among all the explored olivine samples, LiMnPO4 showed highest enhancement in conductivity due to weak Li-O bonding and largest unit cell volume.

  1. The development of low cost LiFePO4-based high power lithium-ion batteries

    SciTech Connect

    Shim, Joongpyo; Sierra, Azucena; Striebel, Kathryn A.

    2003-11-25

    The cycling performance of low-cost LiFePO4-based high-power lithium-ion cells was investigated and the components were analyzed after cycling to determine capacity fade mechanisms. Pouch type LiFePO4/natural graphite cells were assembled and evaluated by constant C/2 cycling, pulse-power and impedance measurements. From post-test electrochemical analysis after cycling, active materials, LiFePO4 and natural graphite, showed no degradation structurally or electrochemically. The main reasons for the capacity fade of cell were lithium inventory loss by side reaction and possible lithium deposition on the anode.

  2. Can Vanadium Be Substituted into LiFePO4

    SciTech Connect

    Omenya F.; Nam K.; Chernova N.A.; Upreti S.; Zavalij P.Y.; Nam K.-W.; Yang X.-Q.; Whittingham M.S.

    2011-11-08

    Vanadium is shown to substitute for iron in the olivine LiFePO{sub 4} up to at least 10 mol %, when the synthesis is carried out at 550 C. In the solid solution LiFe{sub 1-3y/2}V{sub y}PO{sub 4}, the a and b lattice parameters and cell volume decrease with increasing vanadium content, while the c lattice parameter increases slightly. However, when the synthesis is performed at 650 C, a NASICON phase, Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}, is also formed, showing that solid solution is a function of the synthesis temperature. X-ray absorption near-edge structure indicates vanadium is in the 3+ oxidation state and in an octahedral environment. Magnetic studies reveal a shift of the antiferromagnetic ordering transition toward lower temperatures with increasing vanadium substitution, confirming solid solution formation. The addition of vanadium enhances the electrochemical performance of the materials especially at high current densities.

  3. Investigation of charge transfer kinetics of Li-Intercalation in LiFePO4

    NASA Astrophysics Data System (ADS)

    Heubner, C.; Schneider, M.; Michaelis, A.

    2015-08-01

    Recent studies point out contradictions between classical Butler-Volmer kinetics and the charge transfer kinetics of lithium intercalation in host materials. In this work the charge transfer kinetics of lithium intercalation in LiFePO4 are investigated using current controlled electrochemical impedance spectroscopy with varying amplitudes. The results point out a significant impact of ohmic and diffusion contributions to the total overpotential which is normally extracted from constant current charging - discharging experiments to determine Tafel-plots, exchange currents and charge transfer coefficients. By the accurate separation of the activation overpotential from the total overpotential the authors are able to show that the charge transfer kinetics of lithium intercalation in LiFePO4 perfectly obey the Butler-Volmer equation.

  4. Optimized electrochemical performance of three-dimensional porous LiFePO4/C microspheres via microwave irradiation assisted synthesis

    NASA Astrophysics Data System (ADS)

    Yu, Feng; Lim, San Hua; Zhen, Yongda; An, Yongxin; Lin, Jianyi

    2014-12-01

    Microwave irradiation assisted synthesis (MIAS) is successfully employed to prepare three-dimensional (3D) porous microspherical aggregation of LiFePO4/C nanoparticles as the cathode material of lithium ion battery. XRD, SEM, and TEM studies confirm that highly crystalline LiFePO4 without any impurity phase can be synthesized under microwave irradiation of 700 W for 5 min. The as-obtained LiFePO4/C sample is prepared via MIAS consisting of nanopores (20-30 nm) and nanoparticles (20-30 nm) which are coated with uniform, complete carbon layers (about ˜3 nm). These superior physical characters provide LiFePO4/C (MIAS) excellent electrochemical performance at 0.1C including the high discharge capacity of 156.9 mAh g-1 and the low polarization of 51.5 mV. At the discharge rate of 1C, LiFePO4/C (MIAS) exhibits the low polarization of 202.3 mV, high capacity of 126.7 mAh g-1, high discharge voltage of 3.33 V, and specific energy of 398.5 kWh kg-1, all of which are much better than those measured for the sample prepared via conventional heat treatment (CHT). At even high rate of 5C, LiFePO4/C (CHT) fails to discharge whereas LiFePO4/C (MIAS) is able to deliver the discharge capacity of 95.5 mAh g-1. The low polarization of LiFePO4/C (MIAS) results in the good discharge voltage of 3.06 V, high specific energy of 278.8 Wh kg-1, and excellent energy efficiency of 72.0% at 5C.

  5. Optimized Operating Range for Large-Format LiFePO4/Graphite Batteries

    SciTech Connect

    Jiang, Jiuchun; Shi, Wei; Zheng, Jianming; Zuo, Pengjian; Xiao, Jie; Chen, Xilin; Xu, Wu; Zhang, Jiguang

    2014-06-01

    e investigated the long-term cycling performance of large format 20Ah LiFePO4/graphite batteries when they are cycled in various state-of-charge (SOC) ranges. It is found that batteries cycled in the medium SOC range (ca. 20~80% SOC) exhibit superior cycling stability than batteries cycled at both ends (0-20% or 80-100%) of the SOC even though the capcity utilized in the medium SOC range is three times as large as those cycled at both ends of the SOC. Several non-destructive techniques, including a voltage interruption approach, model-based parameter identification, electrode impedance spectra analysis, ?Q/?V analysis, and entropy change test, were used to investigate the performance of LiFePO4/graphite batteries within different SOC ranges. The results reveal that batteries at the ends of SOC exhibit much higher polarization impedance than those at the medium SOC range. These results can be attributed to the significant structural change of cathode and anode materials as revealed by the large entropy change within these ranges. The direct correlation between the polarization impedance and the cycle life of the batteries provides an effective methodology for battery management systems to control and prolong the cycle life of LiFePO4/graphite and other batteries.

  6. Mesoscale phase distribution in single particles of LiFePO4 following lithium deintercalation

    PubMed Central

    Boesenberg, Ulrike; Meirer, Florian; Liu, Yijin; Shukla, Alpesh K.; Dell’Anna, Rossana; Tyliszczak, Tolek; Chen, Guoying; Andrews, Joy C.; Richardson, Thomas J.; Kostecki, Robert; Cabana, Jordi

    2013-01-01

    The chemical phase distribution in hydrothermally grown micrometric single crystals LiFePO4 following partial chemical delithiation was investigated. Full field and scanning X-ray microscopy were combined with X-ray absorption spectroscopy at the Fe K- and O K-edges, respectively, to produce maps with high chemical and spatial resolution. The resulting information was compared to morphological insight into the mechanics of the transformation by scanning transmission electron microscopy. This study revealed the interplay at the mesocale between microstructure and phase distribution during the redox process, as morphological defects were found to kinetically determine the progress of the reaction. Lithium deintercalation was also found to induce severe mechanical damage in the crystals, presumably due to the lattice mismatch between LiFePO4 and FePO4. Our results lead to the conclusion that rational design of intercalation-based electrode materials, such as LiFePO4, with optimized utilization and life requires the tailoring of particles that minimize kinetic barriers and mechanical strain. Coupling TXM-XANES with TEM can provide unique insight into the behavior of electrode materials during operation, at scales spanning from nanoparticles to ensembles and complex architectures. PMID:23745016

  7. Mesoscale phase distribution in single particles of LiFePO4 following lithium deintercalation.

    PubMed

    Boesenberg, Ulrike; Meirer, Florian; Liu, Yijin; Shukla, Alpesh K; Dell'anna, Rossana; Tyliszczak, Tolek; Chen, Guoying; Andrews, Joy C; Richardson, Thomas J; Kostecki, Robert; Cabana, Jordi

    2013-05-14

    The chemical phase distribution in hydrothermally grown micrometric single crystals LiFePO4 following partial chemical delithiation was investigated. Full field and scanning X-ray microscopy were combined with X-ray absorption spectroscopy at the Fe K- and O K-edges, respectively, to produce maps with high chemical and spatial resolution. The resulting information was compared to morphological insight into the mechanics of the transformation by scanning transmission electron microscopy. This study revealed the interplay at the mesocale between microstructure and phase distribution during the redox process, as morphological defects were found to kinetically determine the progress of the reaction. Lithium deintercalation was also found to induce severe mechanical damage in the crystals, presumably due to the lattice mismatch between LiFePO4 and FePO4. Our results lead to the conclusion that rational design of intercalation-based electrode materials, such as LiFePO4, with optimized utilization and life requires the tailoring of particles that minimize kinetic barriers and mechanical strain. Coupling TXM-XANES with TEM can provide unique insight into the behavior of electrode materials during operation, at scales spanning from nanoparticles to ensembles and complex architectures. PMID:23745016

  8. Modified solid-state reaction synthesized cathode lithium iron phosphate (LiFePO4) from different phosphate sources.

    PubMed

    Ding, Keqiang; Li, Wenjuan; Wang, Qingfei; Wei, Suying; Guo, Zhanhu

    2012-05-01

    A modified solid-state method was used to prepare LiFePO4. With the aid of deionized water, a mixture containing Fe2O3, NH4H2PO4 (or (NH4)2HPO4), LiOH, glucose and oxalic acid was prepared into fluffy powders, which were heated in a carbon-coated crucible at 700 degrees C for 3 hours to synthesize LiFePO4 without any inert gas flow. For the first time, the roles of NH4H2PO4 and (NH4)2HPO4 on the preparation of LiFePO4 were systematically investigated. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), revealing that the crystallinity of the LiFePO4 sample prepared from NH4H2PO4 is superior to that prepared from (NH4)2HPO4 and the particle size of the sample prepared from NH4H2PO4 is smaller than that prepared from (NH4)2HPO4. The specific capacity, cycle property and rate capabilities were also compared between the as-prepared LiFePO4 samples. A better electrochemical performance was observed in the sample prepared from NH4H2PO4. PMID:22852311

  9. LiFePO 4 safe Li-ion polymer batteries for clean environment

    NASA Astrophysics Data System (ADS)

    Zaghib, K.; Charest, P.; Guerfi, A.; Shim, J.; Perrier, M.; Striebel, K.

    The performance of natural graphite-fibers/PEO-based gel electrolyte/LiFePO 4 cells (7 mAh, 4 cm 2) is reported. The gel polymer electrolytes were produced by electron-beam irradiation and then soaked in a liquid electrolyte. The natural graphite-fiber composite anode in gel electrolyte containing 1.5 M LiFSI-EC/GBL (1:3) exhibited high reversible capacity (361 mAh g -1) and high Coulombic efficiency (92%). The LiFePO 4 cathode in the same gel polymer exhibited a reversible capacity of 161 mAh g -1 and 93% Coulombic efficiency. A 1.5 M solution of LiFSI in ethylene carbonate (EC)/?-butyrolactone (GBL) (1:3, v/v) mixed solvent is advantageous for use as the electrolyte in the laminated film bag because of its high flame point (135 °C), high boiling point (219 °C), low vapor pressure and high conductivity (10.2 mS cm -1 at 20 °C). The Li-ion gel polymer battery shows a very low capacity fade of 5% after 500 cycles and also has high-rate capability. The Li-ion gel polymer cell using LiFePO 4 cathodes is suitable for HEV applications.

  10. Electrochemical and kinetic studies of ultrafast laser structured LiFePO4 electrodes

    NASA Astrophysics Data System (ADS)

    Mangang, M.; Gotcu-Freis, P.; Seifert, H. J.; Pfleging, W.

    2015-03-01

    Due to a growing demand of cost-efficient lithium-ion batteries with an increased energy and power density as well as an increased life-time, the focus is set on intercalation cathode materials like LiFePO4. It has a high practical capacity, is environmentally friendly and has low material costs. However, its low electrical conductivity and low ionic diffusivity are major drawbacks for its use in electrochemical storage devices or electric vehicles. By adding conductive agents, the electrical conductivity can be enhanced. By increasing the surface of the cathode material which is in direct contact with the liquid electrolyte the lithium-ion diffusion kinetics can be improved. A new approach to increase the surface of the active material without changing the active particle packing density or the weight proportion of carbon black is the laser-assisted generation of 3D surface structures in electrode materials. In this work, ultrafast laser radiation was used to create a defined surface structure in LiFePO4 electrodes. It was shown that by using ultrashort laser pulses instead of nanosecond laser pulses, the ablation efficiency could be significantly increased. Furthermore, melting and debris formation were reduced. To investigate the diffusion kinetics, electrochemical methods such as cyclic voltammetry and galvanostatic intermittent titration technique were applied. It could be shown that due to a laser generated 3D structure, the lithium-ion diffusion kinetic, the capacity retention and cell life-time can be significantly improved.

  11. Additive-free solvothermal synthesis and Li-ion intercalation properties of dumbbell-shaped LiFePO4/C mesocrystals

    E-print Network

    Cao, Guozhong

    Available online 2 April 2013 Keywords: Mesocrystals Lithium iron phosphate Self-assembly Lithium ion battery Cathode Nanorods a b s t r a c t Hierarchical dumbbell-shaped lithium iron phosphate (LiFePO4 coated in-situ by adding sucrose during the solvothermal process and the LiFePO4/C mesocrystals showed

  12. Surface Chemistry of LiFePO4 Studied by Mssbauer and X-Ray Photoelectron Spectroscopy and Its Effect

    E-print Network

    Ryan, Dominic

    Surface Chemistry of LiFePO4 Studied by Mössbauer and X-Ray Photoelectron Spectroscopy and Its cathode material for lithium-ion batteries despite its low intrinsic electronic conductivity. We show, using a combination of Mössbauer, X-ray diffraction, and X-ray photoelectron spectroscopy XPS

  13. Anomalous magnetic structure and spin dynamics in magnetoelectric LiFePO4

    DOE PAGESBeta

    Toft-Petersen, Rasmus; Reehuis, Manfred; Jensen, Thomas B. S.; Andersen, Niels H.; Li, Jiying; Le, Manh Duc; Laver, Mark; Niedermayer, Christof; Klemke, Bastian; Lefmann, Kim; et al

    2015-07-06

    We report significant details of the magnetic structure and spin dynamics of LiFePO4 obtained by single-crystal neutron scattering. Our results confirm a previously reported collinear rotation of the spins away from the principal b axis, and they determine that the rotation is toward the a axis. In addition, we find a significant spin-canting component along c. Furthermore, the possible causes of these components are discussed, and their significance for the magnetoelectric effect is analyzed. Inelastic neutron scattering along the three principal directions reveals a highly anisotropic hard plane consistent with earlier susceptibility measurements. While using a spin Hamiltonian, we showmore »that the spin dimensionality is intermediate between XY- and Ising-like, with an easy b axis and a hard c axis. As a result, it is shown that both next-nearest neighbor exchange couplings in the bc plane are in competition with the strongest nearest neighbor coupling.« less

  14. Synthesis, characterization and vibrational spectroscopic study of Co, Mg co-doped LiMnPO4

    NASA Astrophysics Data System (ADS)

    Sronsri, Chuchai; Noisong, Pittayagorn; Danvirutai, Chanaiporn

    2016-01-01

    The isostructural olivine-like LiM(II)PO4 compounds [M(II) = Mn, Mn0.9Co0.1, Mn0.8Co0.1Mg0.1] were successfully generated through the solid state reaction from the synthesized NH4M(II)PO4• H2O precursors. The TG/DTG/DTA, AAS/AES, FTIR and XRD methods were employed to confirm both NH4M(II)PO4• H2O and LiM(II)PO4 compounds. Their morphologies were studied by SEM method. The shift of two theta angle of XRD to higher values was observed in metal doping compounds, which indicate the formation of the single phase of isodivalent doping of Co2 + and Mg2 + ions according to the change in the lattice parameters and cell volumes. Their infrared spectra are reported and discussed with respect to the normal vibrations of NH4+, PO43 -, P2O74 - and H2O molecules using factor group analysis. The correlation field splitting analysis of PO43 - in NH4M(II)PO4• H2O (orthorhombic system, Pmn21, C2v7 and Z = 2, [(3 × 5) - 6] × 2 = 18 internal modes) symbolized as Td - Cs - C2v7 suggested the number of vibrational modes to be: ?Vib = A1(6) + A2(3) + B1(6) + B2(3) and A1(6) + A2(3) + B1(3) + B2(6) for zx and yz plane respectively. While, LiM(II)PO4 crystallizes in the orthorhombic system the space group Pnma (D2h16), Z = 4 and the site symmetry of PO43 - is Cs. The correlation field splitting of type Td - Cs - D2h16 were reported in relation to [(3 × 5) - 6] × 4 = 36 internal modes for PO43 - unit in the structure.

  15. Synthesis, characterization and vibrational spectroscopic study of Co, Mg co-doped LiMnPO4.

    PubMed

    Sronsri, Chuchai; Noisong, Pittayagorn; Danvirutai, Chanaiporn

    2016-01-15

    The isostructural olivine-like LiM(II)PO4 compounds [M(II)=Mn, Mn0.9Co0.1, Mn0.8Co0.1Mg0.1] were successfully generated through the solid state reaction from the synthesized NH4M(II)PO4?H2O precursors. The TG/DTG/DTA, AAS/AES, FTIR and XRD methods were employed to confirm both NH4M(II)PO4?H2O and LiM(II)PO4 compounds. Their morphologies were studied by SEM method. The shift of two theta angle of XRD to higher values was observed in metal doping compounds, which indicate the formation of the single phase of isodivalent doping of Co(2+) and Mg(2+) ions according to the change in the lattice parameters and cell volumes. Their infrared spectra are reported and discussed with respect to the normal vibrations of NH4(+), PO4(3-), P2O7(4-) and H2O molecules using factor group analysis. The correlation field splitting analysis of PO4(3-) in NH4M(II)PO4?H2O (orthorhombic system, Pmn21, C2v(7) and Z=2, [(3×5)-6]×2=18 internal modes) symbolized as Td-Cs-C2v(7) suggested the number of vibrational modes to be: ?Vib=A1(6)+A2(3)+B1(6)+B2(3) and A1(6)+A2(3)+B1(3)+B2(6) for zx and yz plane respectively. While, LiM(II)PO4 crystallizes in the orthorhombic system the space group Pnma (D2h(16)), Z=4 and the site symmetry of PO4(3-) is Cs. The correlation field splitting of type Td-Cs-D2h(16) were reported in relation to [(3×5)-6]×4=36 internal modes for PO4(3-) unit in the structure. PMID:26363729

  16. Nanoscale LiFePO4 and Li4Ti5O12 for High Rate Li-ion Batteries

    SciTech Connect

    Jaiswal, A.; Horne, C.R.; Chang, O.; Zhang, W.; Kong, W.; Wang, E.; Chern, T.; Doeff, M. M.

    2009-08-04

    The electrochemical performances of nanoscale LiFePO4 and Li4Ti5O12 materials are described in this communication. The nanomaterials were synthesized by pyrolysis of an aerosol precursor. Both compositions required moderate heat-treatment to become electrochemically active. LiFePO4 nanoparticles were coated with a uniform, 2-4 nm thick carbon-coating using an organic precursor in the heat treatment step and showed high tap density of 1.24 g/cm3, in spite of 50-100 nm particle size and 2.9 wtpercent carbon content. Li4Ti5O12 nanoparticles were between 50-200 nm in size and showed tap density of 0.8 g/cm3. The nanomaterials were tested both in half cell configurations against Li-metal and also in LiFePO4/Li4Ti5O12 full cells. Nano-LiFePO4 showed high discharge rate capability with values of 150 and 138 mAh/g at C/25 and 5C, respectively, after constant C/25 charges. Nano-Li4Ti5O12 also showed high charge capability with values of 148 and 138 mAh/g at C/25 and 5C, respectively, after constant C/25 discharges; the discharge (lithiation) capability was comparatively slower. LiFePO4/Li4Ti5O12 full cells deliver charge/discharge capacity values of 150 and 122 mAh/g at C/5 and 5C, respectively.

  17. Why LiFePO4 is a safe battery electrode: Coulomb repulsion induced electron-state reshuffling upon lithiation.

    PubMed

    Liu, Xiaosong; Wang, Yung Jui; Barbiellini, Bernardo; Hafiz, Hasnain; Basak, Susmita; Liu, Jun; Richardson, Thomas; Shu, Guojiun; Chou, Fangcheng; Weng, Tsu-Chien; Nordlund, Dennis; Sokaras, Dimosthenis; Moritz, Brian; Devereaux, Thomas P; Qiao, Ruimin; Chuang, Yi-De; Bansil, Arun; Hussain, Zahid; Yang, Wanli

    2015-10-21

    LiFePO4 is a battery cathode material with high safety standards due to its unique electronic structure. We performed systematic experimental and theoretical studies based on soft X-ray emission, absorption, and hard X-ray Raman spectroscopy of LixFePO4 nanoparticles and single crystals. The results clearly show a non-rigid electron-state reconfiguration of both the occupied and unoccupied Fe-3d and O-2p states during the (de)lithiation process. We focus on the energy configurations of the occupied states of LiFePO4 and the unoccupied states of FePO4, which are the critical states where electrons are removed and injected during the charge and discharge process, respectively. In LiFePO4, the soft X-ray emission spectroscopy shows that, due to the Coulomb repulsion effect, the occupied Fe-3d states with the minority spin sit close to the Fermi level. In FePO4, the soft X-ray absorption and hard X-ray Raman spectroscopy show that the unoccupied Fe-3d states again sit close to the Fermi level. These critical 3d electron state configurations are consistent with the calculations based on modified Becke and Johnson potentials GGA+U (MBJGGA+U) framework, which improves the overall lineshape prediction compared with the conventionally used GGA+U method. The combined experimental and theoretical studies show that the non-rigid electron state reshuffling guarantees the stability of oxygen during the redox reaction throughout the charge and discharge process of LiFePO4 electrodes, leading to the intrinsic safe performance of the electrodes. PMID:26388021

  18. A simple and novel Si surface modification on LiFePO4@C electrode and its suppression of degradation of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Wenyu; Zhuang, Zhenyuan; Chen, Xiang; Zou, Mingzhong; Zhao, Guiying; Feng, Qian; Li, Jiaxin; Lin, Yingbin; Huang, Zhigao

    2015-12-01

    A simple and novel surface modification device of the electrodes based on the ultrasonic spray technique was set up, which is considered to have the enormous prospect of industrial application due to its simpleness and high efficiency. Then, the nano-sized Si nanoparticles were deposited uniformly on the LiFePO4@C electrodes. In comparison with pristine LiFePO4@C electrode, the surface modification of the nano-sized Si with crystalline Si core and amorphous Si shell on the electrode surface exhibits less coarsening degree, higher rate capability, better cyclicity at high charge/discharge rate, especially at elevated temperature. Moreover, Raman spectra of LiFePO4@C, LiFePO4@C/Si electrodes before cycles and after 100 cycles at 1 C and 60 °C were measured. It is found that the FePO4 and ?-Fe2O3 phases exist in LiFePO4@C after 100 cycles. On the contrary, there hardly exists the FePO4 and ?-Fe2O3 phases, which means that the nano Si surface modification suppresses the degradation of lithium ion batteries. At last, the schematic and phenomenological resistance models of LiFePO4@C electrode modified by the nano-sized silicon particles have been suggested, which is responsible for the enhancement of the electrochemical performances after nano-sized Si surface modification.

  19. Excellent Temperature Performance of Spherical LiFePO4/C Composites Modified with Composite Carbon and Metal Oxides

    PubMed Central

    Zhang, Bao; Zeng, Tao; Zhang, Jiafeng; Peng, Chunli; Zheng, Junchao; Chen, Guomin

    2014-01-01

    Nanosized spherical LiFePO4/C composite was synthesized from nanosized spherical FePO4·2H2O, Li2C2O4, aluminum oxide, titanium oxide, oxalic acid, and sucrose by binary sintering process. The phases and morphologies of LiFePO4/C were characterized using SEM, TEM, CV, EIS, EDS, and EDX as well as charging and discharging measurements. The results showed that the as-prepared LiFePO4/C composite with good conductive webs from nanosized spherical FePO4·2H2O exhibits excellent electrochemical performances, delivering an initial discharge capacity of 161.7?mAh·g?1 at a 0.1?C rate, 152.4?mAh·g?1 at a 1?C rate and 131.7?mAh·g?1 at a 5?C rate, and the capacity retention of 99.1%, 98.7%, and 95.8%, respectively, after 50 cycles. Meanwhile, the high and low temperature performance is excellent for 18650 battery, maintaining capacity retention of 101.7%, 95.0%, 88.3%, and 79.3% at 55°C, 0°C, ?10°C, and ?20°C by comparison withthat of room temperature (25°C) at the 0.5 C rate over a voltage range of 2.2?V to 3.6?V, respectively. PMID:24526888

  20. Aluminium-doped LiFePO4 single crystals. Part I. Growth, characterization and total conductivity.

    PubMed

    Amin, Ruhul; Lin, Chengtian; Maier, Joachim

    2008-06-28

    Single crystals of Al-doped LiFePO4 (1% Al) were grown by an optical floating zone technique. After cleaving from the as-grown ingot they exhibited a blackish-green color. The grown crystals have been characterized by the Laue X-ray technique, single-crystal and powder X-ray diffraction. Phase composition has been determined by chemical analysis to be Li0.985+/-0.009Fe0.984+/-0.12Al0.0126PO3.993+/-0.06. Secondary ion beam spectroscopy (SIMS) indicates a homogeneous distribution of doped Al in the single crystal block. The total conductivities are shown to be electronic conductivities and have been measured along different directions with the help of the cell Ti/LiFe(Al)PO4/Ti. The samples exhibit effectively two-dimensional electronic conductivities along b- and c-directions similar as in pure LiFePO4. This decrease of conductivity on Al-doping compared with undoped crystals is in agreement with our previous conclusion of p-type conductivity of LiFePO4. Unlike nominally pure material not only the association of holes with lithium vacancies plays an important role but also purely ionic association. PMID:18548157

  1. Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model.

    PubMed

    Delmas, C; Maccario, M; Croguennec, L; Le Cras, F; Weill, F

    2008-08-01

    Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO(4) and FePO(4). As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities. PMID:18641656

  2. Desired crystal oriented LiFePO4 nanoplatelets in situ anchored on a graphene cross-linked conductive network for fast lithium storage.

    PubMed

    Wang, Bo; Liu, Anmin; Abdulla, Wael Al; Wang, Dianlong; Zhao, X S

    2015-05-21

    Electron transfer and lithium ion diffusion rates are the key factors limiting the lithium ion storage in anisotropic LiFePO4 electrodes. In this work, we employed a facile solvothermal method to synthesize a "platelet-on-sheet" LiFePO4/graphene composite (LFP@GNs), which is LiFePO4 nanoplatelets in situ grown on graphene sheets with highly oriented (010) facets of LiFePO4 crystals. Such a two-phase contact mode with graphene sheets cross-linked to form a three-dimensional porous network is favourable for both fast lithium ion and electron transports. As a result, the designed LFP@GNs displayed a high rate capability (?56 mA h g(-1) at 60 C) and long life cycling stability (?87% capacity retention over 1000 cycles at 10 C). For comparison purposes, samples ex situ modified with graphene (LFP/GNs) as well as pure LiFePO4 platelets (LFP) were also prepared and investigated. More importantly, the obtained LFP@GNs can be used as a basic unit for constructing more complex structures to further improve electrochemical performance, such as coating the exposed LFP surface with a thin layer of carbon to build a C@LFP@GN composite to further enhance its cycling stability (?98% capacity retention over 1000 cycles at 10 C). PMID:25908535

  3. Etched Colloidal LiFePO4 Nanoplatelets toward High-Rate Capable Li-Ion Battery Electrodes

    PubMed Central

    2014-01-01

    LiFePO4 has been intensively investigated as a cathode material in Li-ion batteries, as it can in principle enable the development of high power electrodes. LiFePO4, on the other hand, is inherently “plagued” by poor electronic and ionic conductivity. While the problems with low electron conductivity are partially solved by carbon coating and further by doping or by downsizing the active particles to nanoscale dimensions, poor ionic conductivity is still an issue. To develop colloidally synthesized LiFePO4 nanocrystals (NCs) optimized for high rate applications, we propose here a surface treatment of the NCs. The particles as delivered from the synthesis have a surface passivated with long chain organic surfactants, and therefore can be dispersed only in aprotic solvents such as chloroform or toluene. Glucose that is commonly used as carbon source for carbon-coating procedure is not soluble in these solvents, but it can be dissolved in water. In order to make the NCs hydrophilic, we treated them with lithium hexafluorophosphate (LiPF6), which removes the surfactant ligand shell while preserving the structural and morphological properties of the NCs. Only a roughening of the edges of NCs was observed due to a partial etching of their surface. Electrodes prepared from these platelet NCs (after carbon coating) delivered a capacity of ?155 mAh/g, ?135 mAh/g, and ?125 mAh/g, at 1 C, 5 C, and 10 C, respectively, with significant capacity retention and remarkable rate capability. For example, at 61 C (10.3 A/g), a capacity of ?70 mAh/g was obtained, and at 122 C (20.7 A/g), the capacity was ?30 mAh/g. The rate capability and the ease of scalability in the preparation of these surface-treated nanoplatelets make them highly suitable as electrodes in Li-ion batteries. PMID:25372361

  4. Comparison between different LiFePO 4 synthesis routes and their influence on its physico-chemical properties

    NASA Astrophysics Data System (ADS)

    Franger, Sylvain; Le Cras, Frédéric; Bourbon, Carole; Rouault, Hélène

    LiFePO 4 powders were synthesized under several different conditions (solid state reactions at high temperatures, co-precipitation in aqueous medium, hydrothermal synthesis or mechanochemical activation). The samples were characterized by X-ray diffraction (XRD), chemical titration and their electrochemical performance were investigated in terms of cycling behavior. We also report, in this work, the benefit of introducing an electronic conductor precursor (typically a sucrose) during or after the synthesis in order to overcome the poor charge transfer associated with the lithium iron phosphate.

  5. Li-Ion Battery with LiFePO4 Cathode and Li4Ti5O12 Anode for Stationary Energy Storage

    SciTech Connect

    Wang, Wei; Choi, Daiwon; Yang, Zhenguo

    2013-01-01

    i-ion batteries based on commercially available LiFePO4 cathode and Li4Ti5O12 anode were investigated for potential stationary energy storage applications. The full cell that operated at flat 1.85V demonstrated stable cycling for 200 cycles followed by a rapid fade. A significant improvement in cycling stability was achieved via Ketjen black coating of the cathode. A Li-ion full cell with Ketjen black modified LiFePO4 cathode and an unmodified Li4Ti5O12 anode exhibited negligible fade after more than 1200 cycles with a capacity of ~130mAh/g. The improved stability, along with its cost-effectiveness, environmentally benignity and safety, make the LiFePO4/ Li4Ti5O12 Li-ion battery a promising option of storing renewable energy.

  6. Sequential Monte Carlo filter for state estimation of LiFePO4 batteries based on an online updated model

    NASA Astrophysics Data System (ADS)

    Li, Jiahao; Klee Barillas, Joaquin; Guenther, Clemens; Danzer, Michael A.

    2014-02-01

    Battery state monitoring is one of the key techniques in battery management systems e.g. in electric vehicles. An accurate estimation can help to improve the system performance and to prolong the battery remaining useful life. Main challenges for the state estimation for LiFePO4 batteries are the flat characteristic of open-circuit-voltage over battery state of charge (SOC) and the existence of hysteresis phenomena. Classical estimation approaches like Kalman filtering show limitations to handle nonlinear and non-Gaussian error distribution problems. In addition, uncertainties in the battery model parameters must be taken into account to describe the battery degradation. In this paper, a novel model-based method combining a Sequential Monte Carlo filter with adaptive control to determine the cell SOC and its electric impedance is presented. The applicability of this dual estimator is verified using measurement data acquired from a commercial LiFePO4 cell. Due to a better handling of the hysteresis problem, results show the benefits of the proposed method against the estimation with an Extended Kalman filter.

  7. Impact of carbon structure and morphology on the electrochemical performance of LiFePO4/C composites

    SciTech Connect

    Doeff, Marca M.; Doeff, Marca M.; Wilcox, James D.; Yu, Rong; Aumentado, Albert; Marcinek, Marek; Kostecki, Robert

    2007-09-19

    The electrochemical performance of LiFePO4/C composites in lithium cells is closely correlated to pressed pellet conductivities measured by AC impedance methods. These composite conductivities are a strong function not only of the amount of carbon but of its structure and distribution. Ideally, the amount of carbon in composites should be minimal (less than about 2 wtpercent) so as not to decrease the energy density unduly. This is particularly important for plug-in hybrid electric vehicle applications (PHEVs) where both high power and moderate energy density are required. Optimization of the carbon structure, particularly the sp2/sp3 and disordered/graphene (D/G) ratios, improves the electronic conductivity while minimizing the carbon amount. Manipulation of the carbon structure can be achieved via the use of synthetic additives including ironcontaining graphitization catalysts. Additionally, combustion synthesis techniques allow co-synthesis of LiFePO4 and carbon fibers or nanotubes, which can act as"nanowires" for the conduction of current during cell operation.

  8. Optical and surface properties of LiFePO4 thin films prepared by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Volkan, ?enay; Özen, Soner; Pat, Suat; Korkmaz, ?adan

    2015-03-01

    LiFePO4 thin films with thickness values of 65 nm and 70 nm were deposited onto glass substrates by RF magnetron sputtering, using a LiFePO4 target in the argon atmosphere. A comprehensive study of the optical properties was performed and the dispersions of the constants were determined. The transmittance and absorbance spectra were measured in the wavelength range of 400-1000 nm. The films showed optical transmittance over 90% in the visible range. The optical band gap value of the films was evaluated as 3 eV. The refractive index value of the films is 1.63 at ? = 550 nm. AFM micrographs indicate smooth surface with low values ofroot mean square roughness. Contact angle measurements of several testing liquids were used to characterize each sample in terms of wettability. The films are hydrophilic as observed from contact angle measurements. The surface free energy of the film surfaces and their components (dispersive and polar) were calculated from the contact angle data using the different theories available in the literature.

  9. Synthesis and characterization of high power LiFePO4/C nano-plate thin films Nan Zhou a,b

    E-print Network

    Cao, Guozhong

    of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, China c Department of Applied Chemistry, Beijing Institute of Petrochemical Technology, Beijing 102617, China a r t i c l e i n battery Solvothermal growth Nano-carbon coating a b s t r a c t Tunable LiFePO4/C thin films demonstrating

  10. Simulation of effect of interfacial lithium flux on miscibility gap in non-equilibrium phase transformation of LiFePO4 particles

    E-print Network

    Liu, Fuqiang

    transformation of LiFePO4 particles N.A. Siddique a , Ashley M. Allen b , Partha P. Mukherjee c,*, Fuqiang Liu a at Arlington, Arlington, TX 76019, USA b Department of Physics, University of Texas at Arlington, Arlington, TX transition. Two-phase transition is found to be remarkably delayed for spherical particles. Growth of Li

  11. Desired crystal oriented LiFePO4 nanoplatelets in situ anchored on a graphene cross-linked conductive network for fast lithium storage

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Liu, Anmin; Abdulla, Wael Al; Wang, Dianlong; Zhao, X. S.

    2015-05-01

    Electron transfer and lithium ion diffusion rates are the key factors limiting the lithium ion storage in anisotropic LiFePO4 electrodes. In this work, we employed a facile solvothermal method to synthesize a ``platelet-on-sheet'' LiFePO4/graphene composite (LFP@GNs), which is LiFePO4 nanoplatelets in situ grown on graphene sheets with highly oriented (010) facets of LiFePO4 crystals. Such a two-phase contact mode with graphene sheets cross-linked to form a three-dimensional porous network is favourable for both fast lithium ion and electron transports. As a result, the designed LFP@GNs displayed a high rate capability (~56 mA h g-1 at 60 C) and long life cycling stability (~87% capacity retention over 1000 cycles at 10 C). For comparison purposes, samples ex situ modified with graphene (LFP/GNs) as well as pure LiFePO4 platelets (LFP) were also prepared and investigated. More importantly, the obtained LFP@GNs can be used as a basic unit for constructing more complex structures to further improve electrochemical performance, such as coating the exposed LFP surface with a thin layer of carbon to build a C@LFP@GN composite to further enhance its cycling stability (~98% capacity retention over 1000 cycles at 10 C).Electron transfer and lithium ion diffusion rates are the key factors limiting the lithium ion storage in anisotropic LiFePO4 electrodes. In this work, we employed a facile solvothermal method to synthesize a ``platelet-on-sheet'' LiFePO4/graphene composite (LFP@GNs), which is LiFePO4 nanoplatelets in situ grown on graphene sheets with highly oriented (010) facets of LiFePO4 crystals. Such a two-phase contact mode with graphene sheets cross-linked to form a three-dimensional porous network is favourable for both fast lithium ion and electron transports. As a result, the designed LFP@GNs displayed a high rate capability (~56 mA h g-1 at 60 C) and long life cycling stability (~87% capacity retention over 1000 cycles at 10 C). For comparison purposes, samples ex situ modified with graphene (LFP/GNs) as well as pure LiFePO4 platelets (LFP) were also prepared and investigated. More importantly, the obtained LFP@GNs can be used as a basic unit for constructing more complex structures to further improve electrochemical performance, such as coating the exposed LFP surface with a thin layer of carbon to build a C@LFP@GN composite to further enhance its cycling stability (~98% capacity retention over 1000 cycles at 10 C). Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01831e

  12. Ink-jet printed porous composite LiFePO4 electrode from aqueous suspension for microbatteries

    NASA Astrophysics Data System (ADS)

    Delannoy, P.-E.; Riou, B.; Brousse, T.; Le Bideau, J.; Guyomard, D.; Lestriez, B.

    2015-08-01

    This work demonstrates ink-jet printed LiFePO4-based composite porous electrodes for microbattery application. As binder and dispersant, we found that aqueous inks with more suitable rheological properties with respect to ink-jet printing are prepared with the low molecular weight poly-acrylic-co-maleic acid copolymer, rather than with the carboxymethyl cellulose standard binder of the lithium-ion technology. The ink-jet printed thin and porous electrode shows very high rate charge/discharge behavior, both in LiPF6/ethylene carbonate-dimethyl carbonate (LP30) and lithium bis(trifluoromethane)sulfonylimide salt (Li-TFSI) in N-methyl-N-propylpyrrolidinium bis(trifluoromethane)suflonylimide ionic liquid (PYR13-TFSI) electrolytes, as well as good cyclability.

  13. Simplified electrochemical multi-particle model for LiFePO4 cathodes in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Mastali Majdabadi, Mehrdad; Farhad, Siamak; Farkhondeh, Mohammad; Fraser, Roydon A.; Fowler, Michael

    2015-02-01

    A simplified physics-based model is developed to predict the performance of an LiFePO4 cathode at various operating and design conditions. Newman's full-order porous-electrode model is simplified using polynomial approximations for electrolyte variables at the electrode-level while a multi-particle model featuring variable solid-state diffusivity is employed at the particle level. The computational time of this reduced-order model is decreased by almost one order of magnitude compared to the full-order model without sacrificing the accuracy of the results. The model is general and can be used to expedite the simulation of any composite electrode with active-material particles of non-uniform properties (e.g., size, contact resistance, material chemistry etc.). In a broader perspective, this model is of practical value for electric vehicle power train simulations and battery management systems.

  14. Metal Foam as Positive Electrode Current Collector for LiFePO4-Based Li-Ion Battery

    NASA Astrophysics Data System (ADS)

    Yang, Gui Fu; Song, Jae Sun; Kim, Hyung Yoon; Joo, Seung Ki

    2013-10-01

    In order to improve the kinetic performance of LiFePO4-based Li-ion batteries, three dimensional metal foams were used as positive current collector. In the case of conventional Ni foam, the organic electrolyte of the cell was decomposed with the ionization of Ni during charge and discharge. The low tolerance of Ni was solved by using NiCrAl foam which was manufactured by alloying NiCrAl powder with Ni foam. From the electrochemical analysis, it shows that the kinetic performance of the cell by using a three dimensional NiCrAl foam was much superior to that in the case of conventional foil type.

  15. Image based modelling of microstructural heterogeneity in LiFePO4 electrodes for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Cooper, S. J.; Eastwood, D. S.; Gelb, J.; Damblanc, G.; Brett, D. J. L.; Bradley, R. S.; Withers, P. J.; Lee, P. D.; Marquis, A. J.; Brandon, N. P.; Shearing, P. R.

    2014-02-01

    Battery and fuel cell simulations commonly assume that electrodes are macro-homogeneous and isotropic. These simulations have been used to successfully model performance, but give little insight into predicting failure. In Li-ion battery electrodes, it is understood that local tortuosity impacts charging rates, which may cause increased degradation. This report describes a novel approach to quantifying tortuosity based on a heat transfer analogy applied to X-ray microscopy data of a commercially available LiFePO4 electrode. This combination of X-ray imaging and image-based simulation reveals the microscopic performance of the electrode; notably, the tortuosity was observed to vary significantly depending on the direction considered, which suggests that tortuosity might best be quantified using vectors rather than scalars.

  16. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ? 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures. PMID:26328435

  17. The effect of Cr doping on Li ion diffusion in LiFePO4 from first principles investigations and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Ouyang, C. Y.; Shi, S. Q.; Wang, Z. X.; Li, H.; Huang, X. J.; Chen, L. Q.

    2004-04-01

    Using the adiabatic trajectory method, the migration energy barriers for the migration of Li ions and Cr ions along the one-dimensional diffusion pathway in pure and Cr doped LiFePO4 are obtained from first principles calculations. The results show that while Li ions can diffuse along the diffusion pathway easily, Cr ions do not easily diffuse away from their initial positions. This means that the heavy Cr ions will block the one-dimensional diffusion pathway of the material. Monte Carlo simulations are performed to evaluate the influences of the blocking behaviours on the electrochemical performance of LiFePO4 cathode material for Li ion secondary batteries. The results show that the evaluated capacity is highly sensitive to the amount of the dopant, the size of the super-cell being used for simulation (particle size of the powder cathode material) and the Monte Carlo steps for statistics (charge-discharge current density).

  18. Synthesis of LiFePO4/C cathode materials by carbothermal reduction method using two kinds of Fe3+ precursors

    NASA Astrophysics Data System (ADS)

    Zhong, M. E.; Zhou, Z. T.

    2009-09-01

    LiFePO4/C cathode materials were synthesized by carbothermal reduction method using FePO4 and citrate ferric (FeC6H5O7·5H2O) as Fe3+ precursors. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectrometry (XPS) and charge-discharge test. The results showed that both the crystallization degree and particle size increased markedly with the increase of synthesis temperature. Among the synthesized cathode materials, LiFePO4/C prepared at 650°C showed the best electrochemical properties with an initial discharge specific capacity of 138 mAh·g-1 at 0.2 C, 128 mAh·g-1 at 0.5 C and 116 mAh·g-1 at 1.0 C, respectively.

  19. Effects of Particle Size, Electronic Connectivity, and Incoherent Nanoscale Domains on the Sequence of Lithiation in LiFePO4 Porous Electrodes.

    PubMed

    Li, Yiyang; Meyer, Sophie; Lim, Jongwoo; Lee, Sang Chul; Gent, William E; Marchesini, Stefano; Krishnan, Harinarayan; Tyliszczak, Tolek; Shapiro, David; Kilcoyne, Arthur L David; Chueh, William C

    2015-11-01

    High-resolution X-ray microscopy is used to investigate the sequence of lithiation in LiFePO4 porous electrodes. For electrodes with homogeneous interparticle electronic connectivity via the carbon black network, the smaller particles lithiate first. For electrodes with heterogeneous connectivity, the better-connected particles preferentially lithiate. Correlative electron and X-ray microscopy also reveal the presence of incoherent nanodomains that lithiate as if they are separate particles. PMID:26423560

  20. Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries

    NASA Astrophysics Data System (ADS)

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-09-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ~20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4.

  1. Electrochemical Behavior of LiFePO4 Thin Film Prepared by RF Magnetron Sputtering in Li2SO4 Aqueous Electrolyte

    NASA Astrophysics Data System (ADS)

    Wu, Jiaxiong; Cai, Wei; Shang, Guangyi

    2014-01-01

    LiFePO4 films were deposited on Au/Si substrate by radio-frequency magnetron sputtering. The effect of annealing on the crystallization and morphology of LiFePO4 thin film has been investigated. X-ray diffraction revealed that the films through annealing were well crystallized compared with as-deposited films. The surface morphology of the thin film was also observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electrochemical tests in 1M Li2SO4 showed that the annealed thin film in 500°C exhibits larger Li-ion diffusion coefficient (3.46 × 10-7 cm2s-1) than as-deposited film and powder. Furthermore, cyclic voltammetry demonstrate a well-defined lithium intercalation/deintercalation reaction at around 0.45 V versus SCE (i.e., 3.6 V versus Li+/Li), suggesting that the annealed LiFePO4 thin film is a promising candidate cathode film for lithium microbatteries.

  2. Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries.

    PubMed

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-01-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ?20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4. PMID:26345306

  3. Increasing the Affinity Between Carbon-Coated LiFePO4/C Electrodes and Conventional Organic Electrolyte by Spontaneous Grafting of a Benzene-Trifluoromethylsulfonimide Moiety.

    PubMed

    Delaporte, Nicolas; Perea, Alexis; Lebègue, Estelle; Ladouceur, Sébastien; Zaghib, Karim; Bélanger, Daniel

    2015-08-26

    The grafting of benzene-trifluoromethylsulfonimide groups on LiFePO4/C was achieved by spontaneous reduction of in situ generated diazonium ions of the corresponding 4-amino-benzene-trifluoromethylsulfonimide. The diazotization of 4-amino-benzene-trifluoromethylsulfonimide was a slow process that required a high concentration of precursors to promote the spontaneous grafting reaction. Contact angle measurements showed a hydrophilic surface was produced after the reaction that is consistent with grafting of benzene-trifluoromethylsulfonimide groups. Elemental analysis data revealed a 2.1 wt % loading of grafted molecules on the LiFePO4/C powder. Chemical oxidation of the cathode material during the grafting reaction was detected by X-ray diffraction and quantified by inductively coupled plasma atomic emission spectrometry. Surface modification improves the wettability of the cathode material, and better discharge capacities were obtained for modified electrodes at high C-rate. In addition, electrochemical impedance spectroscopy showed the resistance of the modified cathode was lower than that of the bare LiFePO4/C film electrode. Moreover, the modified cathode displayed superior capacity retention after 200 cycles of charge/discharge at 1 C. PMID:26186016

  4. Combined operando X-ray diffraction–electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries

    PubMed Central

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-01-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ?20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4. PMID:26345306

  5. LiFePO4 microcrystals as an efficient heterogeneous Fenton-like catalyst in degradation of rhodamine 6G.

    PubMed

    Li, Zhan Jun; Ali, Ghafar; Kim, Hyun Jin; Yoo, Seong Ho; Cho, Sung Oh

    2014-01-01

    We present a novel heterogeneous Fenton-like catalyst of LiFePO4 (LFP). LFP has been widely used as an electrode material of a lithium ion battery, but we observed that commercial LFP (LFP-C) could act as a good Fenton-like catalyst to decompose rhodamine 6G. The catalytic activity of LFP-C microparticles was much higher than a popular catalyst, magnetite nanoparticles. Furthermore, we found that the catalytic activity of LFP-C could be further increased by increasing the specific surface area. The reaction rate constant of the hydrothermally synthesized LFP microcrystals (LFP-H) is at least 18 times higher than that of magnetite nanoparticles even though the particle size of LFP is far larger than magnetite nanoparticles. The LFP catalysts also exhibited a good recycling behavior and high stability under an oxidizing environment. The effects of the experimental parameters such as the concentration of the catalysts, pH, and the concentration of hydrogen peroxide on the catalytic activity of LFP were also analyzed. PMID:24948896

  6. Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P.; Brownrigg, Alex; Wright, Jonathan P.; van Dijk, Niels H.; Wagemaker, Marnix

    2015-09-01

    Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements.

  7. LiFePO4 microcrystals as an efficient heterogeneous Fenton-like catalyst in degradation of rhodamine 6G

    PubMed Central

    2014-01-01

    We present a novel heterogeneous Fenton-like catalyst of LiFePO4 (LFP). LFP has been widely used as an electrode material of a lithium ion battery, but we observed that commercial LFP (LFP-C) could act as a good Fenton-like catalyst to decompose rhodamine 6G. The catalytic activity of LFP-C microparticles was much higher than a popular catalyst, magnetite nanoparticles. Furthermore, we found that the catalytic activity of LFP-C could be further increased by increasing the specific surface area. The reaction rate constant of the hydrothermally synthesized LFP microcrystals (LFP-H) is at least 18 times higher than that of magnetite nanoparticles even though the particle size of LFP is far larger than magnetite nanoparticles. The LFP catalysts also exhibited a good recycling behavior and high stability under an oxidizing environment. The effects of the experimental parameters such as the concentration of the catalysts, pH, and the concentration of hydrogen peroxide on the catalytic activity of LFP were also analyzed. PMID:24948896

  8. Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling

    PubMed Central

    Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P.; Brownrigg, Alex; Wright, Jonathan P.; van Dijk, Niels H.; Wagemaker, Marnix

    2015-01-01

    Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements. PMID:26395323

  9. Particle shapes and surface structures of olivine NaFePO? in comparison to LiFePO?.

    PubMed

    Whiteside, Alexander; Fisher, Craig A J; Parker, Stephen C; Islam, M Saiful

    2014-10-21

    The expansion of batteries into electric vehicle and grid storage applications has driven the development of new battery materials and chemistries, such as olivine phosphate cathodes and sodium-ion batteries. Here we present atomistic simulations of the surfaces of olivine-structured NaFePO4 as a sodium-ion battery cathode, and discuss differences in its morphology compared to the lithium analogue LiFePO4. The calculated equilibrium morphology is mostly isometric in appearance, with (010), (201) and (011) faces dominant. Exposure of the (010) surface is vital because it is normal to the one-dimensional ion-conduction pathway. Platelet and cube-like shapes observed by previous microscopy studies are reproduced by adjusting surface energies. The results indicate that a variety of (nano)particle morphologies can be achieved by tuning surface stabilities, which depend on synthesis methods and solvent conditions, and will be important in optimising electrochemical performance. PMID:25200320

  10. Direct Observation of Active Material Concentration Gradients and Crystallinity Breakdown in LiFePO4 Electrodes During Charge/Discharge Cycling of Lithium Batteries

    PubMed Central

    2014-01-01

    The phase changes that occur during discharge of an electrode comprised of LiFePO4, carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate. PMID:24790684

  11. A method for state-of-charge estimation of LiFePO4 batteries at dynamic currents and temperatures using particle filter

    NASA Astrophysics Data System (ADS)

    Wang, Yujie; Zhang, Chenbin; Chen, Zonghai

    2015-04-01

    The state-of-charge (SOC) estimation for LiFePO4 batteries is one of the most important issues in battery management system (BMS) on electric vehicles (EVs). Significant temperature changes and drift current noises are inevitable in EVs and cause strong interference in SOC estimation, therefore a SOC-Particle filter (PF) estimator is proposed for SOC estimation. This paper tries to make three contributions: (1) a temperature composed battery model is established based on commercial LiFePO4 cells which can be used for SOC estimation at dynamic temperatures. (2) A capacity retention ratio (CRR) aging model is established based on the real history statistical analysis of the running mileage of the battery on an urban bus. (3) The proposed models are combined with an electrochemical model and the PF method is employed for SOC estimation to eliminate the drift noise effects. Experiments under dynamic current and temperature conditions are designed and performed to verify the accuracy and robustness of the proposed method. The numeral results of the validation experiments have verified that accurate and robust SOC estimation results can be obtained by the proposed method.

  12. Electrochemical performance of La2O3/Li2O/TiO2 nano-particle coated cathode material LiFePO4.

    PubMed

    Wang, Hong; Yang, Chi; Liu, Shu-Xin

    2014-09-01

    Cathode material, LiFePO4 was modified by coating with a thin layer of La2O3/Li2O/TiO2 nano-particles for improving its performance for lithium ion batteries. The morphology and structure of the modified cathode material were characterized by powder X-ray diffraction, scanning electron microcopy and AES. The performance of the battery with the modified cathode material, including cycling stability, C-rate discharge was examined. The results show that the battery composed of the coated cathode materials can discharge at a large current density and show stable cycling performance in the range from 2.5 to 4.0 V. The rate of Li ion diffusion increases in the battery with the La2O3/Li2O/TiO2-coated LiFePO4 as a cathode and the coating layer may acts as a faster ion conductor (La(2/3-x)Li(3x)TiO3). PMID:25924344

  13. Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance

    NASA Astrophysics Data System (ADS)

    Asfaw, Habtom D.; Roberts, Matthew R.; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

    2014-07-01

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm-2 at 0.1 mA cm-2 (lowest rate) and 1.1 mA h cm-2 at 6 mA cm-2 (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm-2 at 0.1 mA cm-2 (lowest rate) and 1.1 mA h cm-2 at 6 mA cm-2 (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01682c

  14. Pilot-scale continuous synthesis of a vanadium-doped LiFePO4/C nanocomposite high-rate cathodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Johnson, Ian D.; Lübke, Mechthild; Wu, On Ying; Makwana, Neel M.; Smales, Glen J.; Islam, Husn U.; Dedigama, Rashmi Y.; Gruar, Robert I.; Tighe, Christopher J.; Scanlon, David O.; Corà, Furio; Brett, Dan J. L.; Shearing, Paul R.; Darr, Jawwad A.

    2016-01-01

    A high performance vanadium-doped LiFePO4 (LFP) electrode is synthesized using a continuous hydrothermal method at a production rate of 6 kg per day. The supercritical water reagent rapidly generates core/shell nanoparticles with a thin, continuous carbon coating on the surface of LFP, which aids electron transport dynamics across the particle surface. Vanadium dopant concentration has a profound effect on the performance of LFP, where the composition LiFe0.95V0.05PO4, achieves a specific discharge capacity which is among the highest in the comparable literature (119 mA h g-1 at a discharge rate of 1500 mA g-1). Additionally, a combination of X-ray absorption spectroscopy analysis and hybrid-exchange density functional theory, suggest that vanadium ions replace both phosphorous and iron in the structure, thereby facilitating Li+ diffusion due to Li+ vacancy generation and changes in the crystal structure.

  15. Tungsten diffusion in olivine

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Van Orman, J. A.

    2014-03-01

    Diffusion of tungsten has been characterized in synthetic forsterite and natural olivine (Fo90) under dry conditions. The source of diffusant was a mixture of magnesium tungstate and olivine powders. Experiments were prepared by sealing the source material and polished olivine under vacuum in silica glass ampoules with solid buffers to buffer at NNO or IW. Prepared capsules were annealed in 1 atm furnaces for times ranging from 45 min to several weeks, at temperatures from 1050 to 1450 °C. Tungsten distributions in the olivine were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for W diffusion in forsterite: D=1.0×10-8exp(-365±28 kJ mol/RT) m s Diffusivities for the synthetic forsterite and natural Fe-bearing olivine are similar, and tungsten diffusion in olivine shows little dependence on crystallographic orientation or oxygen fugacity. The slow diffusivities measured for W in olivine indicate that Hf-W ages in olivine-metal systems will close to diffusive exchange at higher temperatures than other chronometers commonly used in cosmochronology, and that tungsten isotopic signatures will be less likely to be reset by subsequent thermal events.

  16. Titanium diffusion in olivine

    NASA Astrophysics Data System (ADS)

    Cherniak, Daniele J.; Liang, Yan

    2014-12-01

    Diffusion of Ti has been characterized in natural olivine and synthetic forsterite. Experiments on the natural olivines were run under buffered conditions (IW and NNO), and those on synthetic forsterite were run in air. Titanium diffusion appears relatively insensitive to crystallographic orientation and oxygen fugacity under the range of investigated conditions, and diffusivities are similar for Fe-bearing olivine and forsterite. For Ti diffusion in synthetic forsterite, we obtain the following Arrhenius relation for diffusion over the temperature range 900-1400 °C:

  17. Rapid Microwave-Assisted Solvothermal Synthesis of Non-Olivine Cmcm Polymorphs of LiMPO4 (M = Mn, Fe, Co, and Ni) at Low Temperature and Pressure.

    PubMed

    Assat, Gaurav; Manthiram, Arumugam

    2015-10-19

    Lithium transition-metal phosphates, LiMPO4 (M = Mn, Fe, Co, and Ni), have attracted significant research interest over the past two decades as an important class of lithium ion battery cathode materials. However, almost all of the investigations thus far have focused on the olivine polymorph that exists in the orthorhombic Pnma space group. In this study, a distinct orthorhombic but non-olivine polymorph of LiMPO4, described by a Cmcm space group symmetry, has been synthesized with M = Mn, Fe, Co, and Ni. Of these, LiMnPO4 in the Cmcm space group is reported for the first time. A rapid microwave-assisted solvothermal (MW-ST) heating process with tetraethylene glycol (TEG) as the solvent and transition-metal oxalates as precursors facilitates the synthesis of these materials. The peak reaction temperatures and pressures were below 300 °C and 30 bar, respectively, which are several orders of magnitude lower than those of the previously reported high-pressure (gigapascals) method. X-ray diffraction (XRD) confirms the crystal structure with the Cmcm space group, and scanning electron micrographs indicate a submicrometer thin platelet-like morphology. The synthesis process conditions have been optimized to obtain impurity-free samples with the correct stoichiometry, as characterized by XRD and inductively coupled plasma-optical emission spectroscopy (ICP-OES). Upon heat treatment to higher temperatures, an irreversible transformation of the metastable Cmcm polymorphs into olivine is observed by XRD and Fourier transform infrared spectroscopy. Although the electrochemical activity of these polymorphs as lithium ion cathodes turns out to be poor, the facile synthesis under mild conditions has permitted easy access to these materials in a nanomorphology, some of which were not even possible before. PMID:26428928

  18. Real-time investigation on the influences of vanadium additives to the structural and chemical state evolutions of LiFePO4 for enhancing the electrochemical performance of lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Hu, Chih-Wei; Chen, Tsan-Yao; Shih, Kai-Sheng; Wu, Pin-Jiun; Su, Hui-Chia; Chiang, Ching-Yu; Huang, An-Feng; Hsieh, Han-Wei; Chang, Chia-Chin; Shew, Bor-Yuan; Lee, Chih-Hao

    2014-12-01

    The influences of adding vanadium to the structure evolution and electrochemical performance of LiFePO4 are systematically investigated by in-situ X-ray powder diffraction and X-ray absorption near edge structure spectroscopy. The results indicate that the addition of a small amount of vanadium (less than at 1%) significantly reduces the formation of non-crystalline (highly disordered) triphylite and remnant heterosite phases in the cathode of battery especially at the rate capability higher than 0.5C. The cycle stability of LiFePO4 cathode with vanadium additive after 80 cycles is improved by 14.9% compared to that without vanadium additive. Such an enhancement could be attributed to the ion diffusion kinetics being improved and inactive triphylite being reduced by the supervalent-vanadium additive in cathode during electrochemical redox cycles.

  19. Electrode Lithiation: Effects of Particle Size, Electronic Connectivity, and Incoherent Nanoscale Domains on the Sequence of Lithiation in LiFePO4 Porous Electrodes (Adv. Mater. 42/2015).

    PubMed

    Li, Yiyang; Meyer, Sophie; Lim, Jongwoo; Lee, Sang Chul; Gent, William E; Marchesini, Stefano; Krishnan, Harinarayan; Tyliszczak, Tolek; Shapiro, David; Kilcoyne, Arthur L David; Chueh, William C

    2015-11-01

    On page 6591, W. Chueh and co-workers use high-resolution X-ray microscopy to study the sequence of lithiation in LiFePO4 battery electrodes and reveal that local electronic connectivity limits the rate capability. For electrodes with homogeneous interparticle electronic connectivity via the carbon black network, the smaller particles lithiate first. For electrodes with heterogeneous connectivity, the better-connected particles preferentially lithiate. PMID:26545179

  20. Artificial meteor ablation studies: Olivine

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.; Cunningham, G. G.

    1973-01-01

    Artificial meteor ablation was performed on a Mg-rich olivine sample using an arc-heated plasma of ionized air. Experimental conditions simulated a meteor traveling about 12 km/sec at an altitude of 70 km. The mineral content of the original olivine sample was 98% olivine (including traces of olivine alteration products) and 2% chromite. Forsterite content of the original olivine was Fo-89. After ablation, the forsterite content had increased to Fo-94 in the recrystallized olivine. In addition, lamella-like intergrowths of magnetite were prevalent constituents. Wherever magnetite occurred, there was an increase in Mg and a corresponding decrease in Fe for the recrystallized olivine. The Allende fusion crust consisted of a recrystallized olivine, which was more Mg-rich and Fe-deficient than the original meteorite's olivine, and abundant magnetite grains. Although troilite and pentlandite were the common opaque mineral constituents in this meteorite, magnetite was the principal opaque mineral found in the fusion crust.

  1. Surface-orientation-dependent distribution of subsurface cation-exchange defects in olivine-phosphate nanocrystals.

    PubMed

    Chung, Sung-Yoon; Choi, Si-Young; Kim, Tae-Hwan; Lee, Seongsu

    2015-01-27

    Atomic-scale exchange between two different cations of similar size in crystalline oxides is one of the major types of point defects when multiple cations in oxygen interstitials are arrayed in an ordered manner. Although a number of studies have been performed on a variety of Li-intercalation olivine phosphates to determine the distribution of exchange defects in bulk, understanding of the thermodynamic stability of the defects in subsurface regions and its dependency on the crystallographic orientation at the surface has remained elusive. Through a combination of small-angle neutron scattering, atomic-scale direct probing with scanning transmission electron microscopy, and theoretical ab initio calculations, we directly demonstrate that the antisite exchange defects are distributed in a highly anisotropic manner near the surfaces of LiFePO4 crystals. Moreover, a substantial amount of cation exchanges between Li and Fe sites is identified as an energetically favorable configuration in some surface regions, showing excellent agreement with the calculation results of negative defect formation energies. The findings in this study provide insight into developing better ways to avoid degradation of lithium mobility through the surface as well as scientifically notable features regarding the distribution of exchange defects in olivine phosphates. PMID:25565086

  2. Conformal Coating Strategy Comprising N-doped Carbon and Conventional Graphene for Achieving Ultrahigh Power and Cyclability of LiFePO4.

    PubMed

    Zhang, Kan; Lee, Jeong-Taik; Li, Ping; Kang, Byoungwoo; Kim, Jung Hyun; Yi, Gi-Ra; Park, Jong Hyeok

    2015-10-14

    Surface carbon coating to improve the inherent poor electrical conductivity of lithium iron phosphate (LiFePO4, LFP) has been considered as most efficient strategy. Here, we also report one of the conventional methods for LFP but exhibiting a specific capacity beyond the theoretical value, ultrahigh rate performance, and excellent long-term cyclability: the specific capacity is 171.9 mAh/g (70 ?m-thick electrode with ?10 mg/cm(2) loading mass) at 0.1 C (17 mA/g) and retains 143.7 mAh/g at 10 C (1.7 A/g) and 95.8% of initial capacity at 10 C after 1000 cycles. It was found that the interior conformal N-C coating enhances the intrinsic conductivity of LFP nanorods (LFP NR) and the exterior reduced graphene oxide coating acts as an electrically conducting secondary network to electrically connect the entire electrode. The great electron transport mutually promoted with shorten Li diffusion length on (010) facet exposed LFP NR represents the highest specific capacity value recorded to date at 10 C and ultralong-term cyclability. This conformal carbon coating approach can be a promising strategy for the commercialization of LFP cathode in lithium ion batteries. PMID:26389552

  3. On the complex ageing characteristics of high-power LiFePO4/graphite battery cells cycled with high charge and discharge currents

    NASA Astrophysics Data System (ADS)

    Groot, Jens; Swierczynski, Maciej; Stan, Ana Irina; Kær, Søren Knudsen

    2015-07-01

    Li-ion batteries are known to undergo complex ageing processes, where the operating conditions have a profound and non-linear effect on both calendar life and cycle life. This is especially a challenge for the automotive industry, where the requirements on product lifetime and reliability are demanding. The aim of the present work is to quantify the ageing in terms of capacity fade and impedance growth as a function of operating conditions typical to high-power automotive applications; high charge and discharge rate, elevated temperatures and wide state-of-charge windows. The cycle life of 34 power-optimised LiFePO4/graphite cells was quantified by testing with charge and discharge rates between 1 and 4C-rate, temperatures between +23 °C and +53 °C, and a depth-of-discharge of either 100% or 60%. Although all cells show similar ageing pattern in general, the cycle life and the impedance growth is remarkably different for the tested cases. In addition, it is concluded that high charging rates, high temperatures or intensive cycling do not always lead to a shorter cycle life. One specifically interesting finding is that the combination of 1C-rate discharge in combination with 3.75C-rate charging was found to degrade the tested cells more rapidly than a symmetric cycle with 3.75C-rate in both directions.

  4. Effects of Laser Energy and Wavelength on the Analysis of LiFePO4 Using Laser Assisted Atom Probe Tomography

    SciTech Connect

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Rich; Janssen, Yuri; Kalifah, Peter; Meng, Ying S.

    2015-01-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative accuracy of atom probe tomography (APT) examinations of LiFePO4 (LFP) are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted APT of LFP has revealed distinctly different behaviors. With the use of UV laser the major issue was identified as the preferential loss of oxygen (up to 10 at. %) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ increased the observed oxygen concentration to near its correct stoichiometry and was well correlated with systematically higher concentrations of 16O2+ ions. This observation supports the premise that lower laser energies lead to a higher probability of oxygen molecule ionization. Conversely, at higher laser energies the resultant lower effective electric field reduces the probability of oxygen molecule ionization. Green laser assisted field evaporation led to the selective loss of Li (~50% deficiency) and correct ratios of the remaining elements, including the oxygen concentration. The loss of Li is explained by selective dc evaporation of lithium between laser pulses and relatively negligible oxygen loss as neutrals during green-laser pulsing. Lastly, plotting of multihit events on a Saxey plot for the straight-flight path data (green laser only) revealed a surprising dynamic recombination process for some molecular ions mid-flight.

  5. Entropy change effects on the thermal behavior of a LiFePO4/graphite lithium-ion cell at different states of charge

    NASA Astrophysics Data System (ADS)

    Jalkanen, K.; Aho, T.; Vuorilehto, K.

    2013-12-01

    The enthalpy and entropy changes in a commercial lithium-ion cell were studied by using potentiometric measurements. The experiments were done on the full cell and individually on its electrode materials, LiFePO4 and artificial graphite. The graphite electrode entropy change follows the amount of intercalated lithium, whereas the LFP electrode entropy change is independent of the lithium content. The full cell entropy change behavior can be concluded to originate from the graphite electrode. For the states of charge between 30 and 75%, the full cell entropy change is positive in the discharge direction, causing the cell to absorb heat. Thus when low discharge currents are used, this entropy effect dominates over the irreversible, heat producing losses, and as a result the cell cools down. In the charge direction the entropy change has the same absolute value but is negative in sign. Because of this, the cell produces extra heat in addition to the irreversible heat production, and thus warms up. These phenomena were confirmed in a calorimetric experiment. The thermal behavior results can be utilized in designing the battery pack cooling system and in choosing favorable states of charge for the battery cycling.

  6. Non-uniform aging of cycled commercial LiFePO4//graphite cylindrical cells revealed by post-mortem analysis

    NASA Astrophysics Data System (ADS)

    Klett, Matilda; Eriksson, Rickard; Groot, Jens; Svens, Pontus; Ciosek Högström, Katarzyna; Lindström, Rakel Wreland; Berg, Helena; Gustafson, Torbjörn; Lindbergh, Göran; Edström, Kristina

    2014-07-01

    Aging of power-optimized commercial 2.3 Ah cylindrical LiFePO4//graphite cells to be used in hybrid electric vehicle is investigated and compared for three different aging procedures; (i) using a simulated hybrid electric vehicle cycle within a narrow SOC-range, (ii) using a constant-current cycle over a 100% SOC-range, and (iii) stored during three years at 22 °C. Postmortem analysis of the cells is performed after full-cell electrochemical characterization and discharge. EIS and capacity measurements are made on different parts of the disassembled cells. Material characterization includes SEM, EDX, HAXPES/XPS and XRD. The most remarkable result is that both cycled cells displayed highly uneven aging primarily of the graphite electrodes, showing large differences between the central parts of the jellyroll compared to the outer parts. The aging variations are identified as differences in capacity and impedance of the graphite electrode, associated with different SEI characteristics. Loss of cyclable lithium is mirrored by a varying degree of lithiation in the positive electrode and electrode slippage. The spatial variation in negative electrode degradation and utilization observed is most likely connected to gradients in temperature and pressure, that can give rise to current density and potential distributions within the jellyroll during cycling.

  7. Experiment and simulation of a LiFePO4 battery pack with a passive thermal management system using composite phase change material and graphite sheets

    NASA Astrophysics Data System (ADS)

    Lin, Chunjing; Xu, Sichuan; Chang, Guofeng; Liu, Jinling

    2015-02-01

    A passive thermal management system (TMS) for LiFePO4 battery modules using phase change material (PCM) as the heat dissipation source to control battery temperature rise is developed. Expanded graphite matrix and graphite sheets are applied to compensate low thermal conductivity of PCM and improve temperature uniformity of the batteries. Constant current discharge and mixed charge-discharge duties were applied on battery modules with and without PCM on a battery thermal characteristics test platform. Experimental results show that PCM cooling significantly reduces the battery temperature rise during short-time intense use. It is also found that temperature uniformity across the module deteriorates with the increasing of both discharge time and current rates. The maximum temperature differences at the end of 1C and 2C-rate discharges are both less than 5 °C, indicating a good performance in battery thermal uniformity of the passive TMS. Experiments on warm-keeping performance show that the passive TMS can effectively keep the battery within its optimum operating temperature for a long time during cold weather uses. A three dimensional numerical model of the battery pack with the passive TMS was conducted using ANSYS Fluent. Temperature profiles with respect to discharging time reveal that simulation shows good agreement with experiment at 1C-discharge rate.

  8. Magnetism in olivine-type LiCo1-xFexPO4 cathode materials: bridging theory and experiment.

    PubMed

    Singh, Vijay; Gershinsky, Yelena; Kosa, Monica; Dixit, Mudit; Zitoun, David; Major, Dan Thomas

    2015-11-18

    In the current paper, we present a non-aqueous sol-gel synthesis of olivine type LiCo1-xFexPO4 compounds (x = 0.00, 0.25, 0.50, 0.75, 1.00). The magnetic properties of the olivines are measured experimentally and calculated using first-principles theory. Specifically, the electronic and magnetic properties are studied in detail with standard density functional theory (DFT), as well as by including spin-orbit coupling (SOC), which couples the spin to the crystal structure. We find that the Co(2+) ions exhibit strong orbital moment in the pure LiCoPO4 system, which is partially quenched upon substitution of Co(2+) by Fe(2+). Interestingly, we also observe a non-negligible orbital moment on the Fe(2+) ion. We underscore that the inclusion of SOC in the calculations is essential to obtain qualitative agreement with the observed effective magnetic moments. Additionally, Wannier functions were used to understand the experimentally observed rising trend in the Néel temperature, which is directly related to the magnetic exchange interaction paths in the materials. We suggest that out of layer M-O-P-O-M magnetic interactions (J?) are present in the studied materials. The current findings shed light on important differences observed in the electrochemistry of the cathode material LiCoPO4 compared to the already mature olivine material LiFePO4. PMID:26548581

  9. Microbial Weathering of Olivine

    NASA Technical Reports Server (NTRS)

    McKay, D. S.; Longazo, T. G.; Wentworth, S. J.; Southam, G.

    2002-01-01

    Controlled microbial weathering of olivine experiments displays a unique style of nanoetching caused by biofilm attachment to mineral surfaces. We are investigating whether the morphology of biotic nanoetching can be used as a biosignature. Additional information is contained in the original extended abstract.

  10. "Black-colored olivines" in peridotites: dehydrogenation from hydrous olivines

    NASA Astrophysics Data System (ADS)

    Arai, Shoji; Hoshikawa, Chihiro; Miura, Makoto

    2015-04-01

    Fresh olivines that are black to the naked eye are found in some dunites. Peridotites are easily converted to be black in color, when serpentinized, due to production of secondary fine magnetite particles. The dunites that contain fresh but black-colored olivines are usually coarse-grained. These coarse olivine grains are sometimes very heterogeneous in color; the blackish part grades to whitish parts in single grains. The black color is due to homegeneous distribution of minute (< 10 microns) black particles in olivine. They are rod-like or plate-like in shape in thin section, sometimes being aligned under crystallographic control of the host olivine. Olivines are clear and free of these inclusions around primary chromian spinel inclusions or chromian spinel lamellae (Arai, 1978). Raman spectroscopy indicates the minute black particles are magnetite always associated with diopside. It is interesting to note that olivine in mantle peridotites accompanied by the black-colored dunites is totally free of the black inclusions, giving the ordinary colors (pale yellow to whitish) of Mg-rich olivine. It is not likely that the magnetite inclusions formed through secondary oxidation of olivine by invasion of oxygen, which is possible along cracks or grain boundaries. They most probably formed due to dehydrogenation from primary OH-bearing olivines upon cooling. Hydrogen was quickly diffused out from the olivines to leave magnetite and excess silica. The excess silica was possibly combined with a monticellite component to form diopside. The OH-bearing (hydrous) olivines can be precipitated from hydrous magmas, and the hydrous nature of the magma can promote an increase in grain size due to faster diffusion of elements. The minute inclusions of magnetite + diopside is thus an indicator of primary hydrous character of host olivine.

  11. Helium Diffusion in Olivine

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Watson, E. B.

    2011-12-01

    Diffusion of helium has been characterized in natural Fe-bearing olivine (~Fo90) and synthetic forsterite. Polished, oriented slabs of olivine were implanted with 3He, at 100 keV at a dose of 5x1015/cm2 or at 3.0 MeV at a dose of 1x1016/cm2. A set of experiments on the implanted olivine were run in 1-atm furnaces. In addition to the one-atm experiments, experiments on implanted samples were also run at higher pressures (2.6 and 2.7 GPa) to assess the potential effects of pressure on He diffusion and the applicability of the measured diffusivities in describing He transport in the mantle. The high-pressure experiments were conducted in a piston-cylinder apparatus using an "ultra-soft" pressure cell, with the diffusion sample directly surrounded by AgCl. 3He distributions following experiments were measured with Nuclear Reaction Analysis using the reaction 3He(d,p)4He. This direct profiling method permits us to evaluate anisotropy of diffusion, which cannot be easily assessed using bulk-release methods. For diffusion in forsterite parallel to c we obtain the following Arrhenius relation over the temperatures 250-950°C: D = 3.91x10-6exp(-159 ± 4 kJ mol-1/RT) m2/sec. The data define a single Arrhenius line spanning more than 7 orders of magnitude in D and 700°C in temperature. Diffusion parallel to a appears slightly slower, yielding an activation energy for diffusion of 135 kJ/mol and a pre-exponential factor of 3.73x10-8 m2/sec. Diffusion parallel to b is slower than diffusion parallel to a (by about two-thirds of a log unit); for this orientation an activation energy of 138 kJ/mol and a pre-exponential factor of 1.34x10-8 m2/sec are obtained. This anisotropy is broadly consistent with observations for diffusion of Ni and Fe-Mg in olivine. Diffusion in Fe-bearing olivine (transport parallel to b) agrees within uncertainty with findings for He diffusion in forsterite. The higher-pressure experiments yield diffusivities in agreement with those from the 1-atm experiments, indicating that the results reported here can be reasonably applied to modeling He transport in the upper mantle. The insensitivity of He diffusion to pressure over the investigated range of conditions suggests that compression of the mineral lattice is not sufficient to significantly influence migration of the relatively small helium atoms, which likely diffuse via crystal interstices. The He diffusivities in this work are generally consistent with results from the study of Futagami et al. (1993), who measured He diffusion in natural olivine by outgassing 4He implanted samples, and with the diffusivities measured by bulk-release of 4He and 3He by Shuster et al. (2003), but are about 2 orders of magnitude slower than the recent findings of Tolstikhin et al. (2010) and Blard et al. (2008) . An up-temperature extrapolation of our data also show reasonable agreement with the higher-temperature measurements of Hart (1984). Blard et al. (2008) GCA 72, 3788-3803; Futagami et al. (1993) GCA 57, 3177-3194; Hart (1984) EPSL 70, 297-302; Shuster et al.( 2003) EPSL 217, 19-32; Tolstikhin et al. (2010) GCA 74, 1436-1447

  12. Electrical conduction in olivine

    SciTech Connect

    Schock, R. N.; Duba, A. G.; Shankland, T. J.

    1989-05-10

    This paper reports detailed measurements of electrical conductivitysigma and thermoelectric effect /ital S/ in the mineral olivine and in syntheticforsterite as functions of temperature in the range from 1000/degree/ to1500 /degree/C and oxygen partial pressure in the range from 10/sup /minus/10/ to10/sup 4/ Pa. The two most striking observations are strong conductivityanisotropy in forsterite and a sign change in /ital S/ in olivine at 1390 /degree/C.These results are interpreted to show that both materials have mixed ionic andextrinsic electronic conduction under these conditions. On the basis ofthese interpretations, we infer that forsterite conductivity is dominatedby electronic conduction in the /ital a/ and /ital b/ directions and probably bymovement involving magnesium vacancies in the /ital c/ direction, wherefar higher /ital P//sub O/sub 2//-independent conductivity is observed. Olivineappears to show mixed conduction under all the circumstances observed; at low temperature, electron holes dominate but are superseded bymagnesium vacancies at high temperatures./copyright/ American Geophysical Union 1989

  13. Studies on graphene enfolded olivine composite electrode material via polyol technique for high rate performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Muruganantham, Rasu; Sivakumar, Marimuthu; Subadevi, Rengapillai; Ramaprabhu, Sundara; Wu, Nae-Lih

    2015-09-01

    The graphene enfolded LiFePO4/C composite cathode material has been prepared via low temperature polyol process, followed by a simple chemical reaction method. The low viscous polyol solvent (DEG) (35.7 mPa s at 25°C) and usage of low temperature process (below 245°C) aid the graphene tightly encapsulated on the LiFePO4 surface that plays an important role, especially in the high rate performances over long cycles, efficiently preventing the separation of the graphene and LiFePO4 during the reaction processes, hence realizing the full potential of the active materials. The graphitization on LiFePO4/C remarkably increased the electronic conductivity of LiFePO4. The layered sheets of graphene wrapped on LiFePO4 particles provide void between graphene sheets and LiFePO4 surfaces, which facilitate the diffusion of Li+. This approach opens up a method to attain the theoretical capacity of LiFePO4. The material exhibits a superior electrochemical performance such as initial discharge capacities of 169.6 and 92 mAhg-1 at 0.1 and 30 C rates, respectively. It has an excellent capacity retention and diminutive capacity fading. The nanosize of LiFePO4 particle causes a shorter diffusion path, which reduces the time for Li+ migration between cathode and electrolyte. [Figure not available: see fulltext.

  14. Defects in Microwave Solvothermally Grown Phospho-Olivine Nanoparticles

    SciTech Connect

    Bridges, Craig A; Harrison, Katharine L; Unocic, Raymond R; Idrobo Tapia, Juan C; Paranthaman, Mariappan Parans; Manthiram, Arumugam

    2013-01-01

    Microwave solvothermally (MW-ST) synthesized crystalline nanopowders of LiFePO4 have been structurally characterized using a combination of high resolution powder neutron diffraction, synchrotron X-ray diffraction and HAADF STEM images. The presence of a significant level of defects has been verified for the samples prepared at 255 oC and 275 oC. These temperatures are significantly higher than what has previously been suggested to be the maximum temperature for defect formation in LiFePO4, and their presence likely relates to the rapid synthesis provided by the MW-ST approach. A defect model has been tentatively proposed, though it has been shown that powder diffraction data alone cannot conclusively determine the precise defect distribution in LiFePO4 samples. The model is consistent with other literature reports on nanopowders synthesized at low temperatures, in which the unit cell volume is significantly reduced relative to defect-free, micron-sized LiFePO4 powders.

  15. A reduced order electrochemical and thermal model for a pouch type lithium ion polymer battery with LiNixMnyCo1-x-yO2/LiFePO4 blended cathode

    NASA Astrophysics Data System (ADS)

    Li, Xueyan; Choe, Song-Yul; Joe, Won Tae

    2015-10-01

    LiNixMnyCo1-x-yO2 (NMC) and LiFePO4 (LFP) as a cathode material have been widely employed for cells designed for high power applications. However, NMC needs further improvements in rate capability and stability that can be accomplished by blending it with LFP. Working mechanism of the blended cells is very complex and hard to understand. In addition, characteristics of the blended cells, particularly the plateau and path dependence of LFP materials, make it extremely difficult to estimate the state of charge and state of health using classical electric equivalent circuit models. Therefore, a reduced order model based on electrochemical and thermal principles is developed with objectives for real time applications and validated against experimental data collected from a large format pouch type of lithium ion polymer battery. The model for LFP is based on a shrinking core model along with moving boundary and then integrated into NMC model. Responses of the model that include SOC estimation and responses of current and voltage are compared with those of experiments at CC/CV charging and CC discharging along with different current rates and temperatures. In addition, the model is used to analyze effects of mass ratios between two materials on terminal voltage and heat generation rate.

  16. Supernova olivine from cometary dust

    NASA Technical Reports Server (NTRS)

    Messenger, Scott; Keller, Lindsay P.; Lauretta, Dante S.

    2005-01-01

    An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

  17. Formation of spinel from olivine

    NASA Astrophysics Data System (ADS)

    Liu, Zongwen; Kelly, Patrick M.; Drennan, John; Mora, Peter; Kanda, Hisao

    2004-03-01

    High-resolution transmission electron microscopy (HRTEM) was used to study the olivine to spinel transformation. HRTEM structure images of Mg2GeO4 olivine deformed under a pressure of 6 GPa at 600 °C clearly show that a shear mechanism dominates the transformation. The transformation is not a nucleation and growth mechanism. It also differs in certain crucial aspects from the type of martensitic transformation proposed before. During the transformation, it is a shear movement that brings the oxygen anions to their positions in the spinel structure. An edge dislocation following each shear then puts the cations in their spinel sites. The Burgers' vector of each dislocation is perpendicular to the anion shear direction.

  18. Drastically Enhanced High-Rate Performance of Carbon-Coated LiFePO4 Nanorods Using a Green Chemical Vapor Deposition (CVD) Method for Lithium Ion Battery: A Selective Carbon Coating Process.

    PubMed

    Tian, Ruiyuan; Liu, Haiqiang; Jiang, Yi; Chen, Jiankun; Tan, Xinghua; Liu, Guangyao; Zhang, Lina; Gu, Xiaohua; Guo, Yanjun; Wang, Hanfu; Sun, Lianfeng; Chu, Weiguo

    2015-06-01

    Application of LiFePO4 (LFP) to large current power supplies is greatly hindered by its poor electrical conductivity (10(-9) S cm(-1)) and sluggish Li+ transport. Carbon coating is considered to be necessary for improving its interparticle electronic conductivity and thus electrochemical performance. Here, we proposed a novel, green, low cost and controllable CVD approach using solid glucose as carbon source which can be extended to most cathode and anode materials in need of carbon coating. Hydrothermally synthesized LFP nanorods with optimized thickness of carbon coated by this recipe are shown to have superb high-rate performance, high energy, and power densities, as well as long high-rate cycle lifetime. For 200 C (18s) charge and discharge, the discharge capacity and voltage are 89.69 mAh g(-1) and 3.030 V, respectively, and the energy and power densities are 271.80 Wh kg(-1) and 54.36 kW kg(-1), respectively. The capacity retention of 93.0%, and the energy and power density retention of 93.6% after 500 cycles at 100 C were achieved. Compared to the conventional carbon coating through direct mixing with glucose (or other organic substances) followed by annealing (DMGA), the carbon phase coated using this CVD recipe is of higher quality and better uniformity. Undoubtedly, this approach enhances significantly the electrochemical performance of high power LFP and thus broadens greatly the prospect of its applications to large current power supplies such as electric and hybrid electric vehicles. PMID:25970716

  19. Electrochemical performance of V-doped spinel Li4Ti5O12/C composite anode in Li-half and Li4Ti5O12/LiFePO4-full cell

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Hu, Huai-Chou; Lin, S. J.; Chien, Wen-Chen

    2014-07-01

    This work reports the preparation of a V-doped Li4Ti5O12/C (donated as V-doped LTO/C) composite material, applying a solid-state method. Both metal doping and carbon coating are applied on the Li4Ti5O12 material, enhancing its rate capability and cycle stability. Furan polymer is used as a carbon source, and vanadium (V) is selected as a dopant. The properties of the materials are examined by X-ray diffraction (XRD), micro-Raman, scanning electron microscopy (SEM), high-resolution transmission microscopy (HR-TEM), the AC impedance method, and the galvanostatic charge/discharge method. For comparison, Li4Ti5O12/C composite materials with and without V doping are also examined. The Li4Ti4.90V0.10O12/C composite material achieves discharge capacities of 165.59 and 76.76 mAh g-1 at a 0.2/1C and 0.2/20C rate, respectively. A Li4Ti5O12/LiFePO4 full cell (LTO capacity-limited) is constructed and investigated. The full cell exhibits discharge capacities of 181, 178, 167, 142, 110, and 78 mAh g-1 at 0.2, 0.5, 1, 3, 5, and 10C, respectively. We determine that the Li4Ti4.95V0.05O12/C composite anode is an outstanding candidate for application in high-power Li-ion batteries.

  20. Multiple origins for olivine at Copernicus crater

    NASA Astrophysics Data System (ADS)

    Dhingra, Deepak; Pieters, Carle M.; Head, James W.

    2015-06-01

    Multiple origins for olivine-bearing lithologies at Copernicus crater are recognized based on integrated analysis of data from Chandrayaan-1 Moon Mineralogy Mapper (M3), Lunar Reconnaissance Orbiter (LRO) Narrow Angle Camera (NAC) and Kaguya Terrain Camera (TC). We report the diverse morphological and spectral character of previously known olivine-bearing exposures as well as the new olivine occurrences identified in this study. Prominent albedo differences exist between olivine-bearing exposures in the central peaks and a northern wall unit (the latter being ?40% darker). The low-albedo wall unit occurs as a linear mantling deposit and is interpreted to be of impact melt origin, in contrast with the largely unmodified nature of olivine-bearing peaks. Small and localized occurrences of olivine-bearing lithology have also been identified on the impact melt-rich floor, representing a third geologic setting (apart from crater wall and peaks). Recent remote sensing missions have identified olivine-bearing exposures around lunar basins (e.g. Yamamoto et al., 2010; Pieters et al., 2011; Kramer et al., 2013) and at other craters (e.g. Sun and Li, 2014), renewing strong interest in its origin and provenance. A direct mantle exposure has commonly been suggested in this regard. Our detailed observations of the morphological and spectral diversity in the olivine-bearing exposures at Copernicus have provided critical constraints on their origin and source regions, emphasizing multiple formation mechanisms. These findings directly impact the interpretation of olivine exposures elsewhere on the Moon. Olivine can occur in diverse environments including an impact melt origin, and therefore it is unlikely for all olivine exposures to be direct mantle occurrences as has generally been suggested.

  1. The ascent of kimberlite: Insights from olivine

    NASA Astrophysics Data System (ADS)

    Brett, R. C.; Russell, J. K.; Andrews, G. D. M.; Jones, T. J.

    2015-08-01

    Olivine xenocrysts are ubiquitous in kimberlite deposits worldwide and derive from the disaggregation of mantle-derived peridotitic xenoliths. Here, we provide descriptions of textural features in xenocrystic olivine from kimberlite deposits at the Diavik Diamond Mine, Canada and at Igwisi Hills volcano, Tanzania. We establish a relative sequence of textural events recorded by olivine during magma ascent through the cratonic mantle lithosphere, including: xenolith disaggregation, decompression fracturing expressed as mineral- and fluid-inclusion-rich sealed and healed cracks, grain size and shape modification by chemical dissolution and abrasion, late-stage crystallization of overgrowths on olivine xenocrysts, and lastly, mechanical milling and rounding of the olivine cargo prior to emplacement. Ascent through the lithosphere operates as a "kimberlite factory" wherein progressive upward dyke propagation of the initial carbonatitic melt fractures the overlying mantle to entrain and disaggregate mantle xenoliths. Preferential assimilation of orthopyroxene (Opx) xenocrysts by the silica-undersaturated carbonatitic melt leads to deep-seated exsolution of CO2-rich fluid generating buoyancy and supporting rapid ascent. Concomitant dissolution of olivine produces irregular-shaped relict grains preserved as cores to most kimberlitic olivine. Multiple generations of decompression cracks in olivine provide evidence for a progression in ambient fluid compositions (e.g., from carbonatitic to silicic) during ascent. Numerical modelling predicts tensile failure of xenoliths (disaggregation) and olivine (cracks) over ascent distances of 2-7 km and 15-25 km, respectively, at velocities of 0.1 to >4 m s-1. Efficient assimilation of Opx during ascent results in a silica-enriched, olivine-saturated kimberlitic melt (i.e. SiO2 >20 wt.%) that crystallizes overgrowths on partially digested and abraded olivine xenocrysts. Olivine saturation is constrained to occur at pressures <1 GPa; an absence of decompression cracks within olivine overgrowths suggests depths <25 km. Late stage (<25 km) resurfacing and reshaping of olivine by particle-particle milling is indicative of turbulent flow conditions within a fully fluidized, gas-charged, crystal-rich magma.

  2. Crystallization kinetics of olivine-phyric shergottites

    NASA Astrophysics Data System (ADS)

    Ennis, Megan E.; McSween, Harry Y.

    2014-08-01

    Crystal size distribution (CSD) and spatial distribution pattern (SDP) analyses are applied to the early crystallizing phases, olivine and pyroxene, in olivine-phyric shergottites (Elephant moraine [EET] 79001A, Dar al Gani [DaG] 476, and dhofar [Dho] 019) from each sampling locality inferred from Mars ejection ages. Trace element zonation patterns (P and Cr) in olivine are also used to characterize the crystallization history of these Martian basalts. Previously reported 2-D CSDs for these meteorites are re-evaluated using a newer stereographically corrected methodology. Kinks in the olivine CSD plots suggest several populations that crystallized under different conditions. CSDs for pyroxene in DaG 476 and EET 79001A reveal single populations that grew under steady-state conditions; pyroxenes in Dho 019 were too intergrown for CSD analysis. Magma chamber residence times of several days for small grains to several months for olivine megacrysts are calculated using the CSD slopes and growth rates inferred from previous experimental data. Phosphorus imaging in olivines in DaG 476 and Dho 019 indicate rapid growth of skeletal, sector-zoned, or patchy cores, probably in response to delayed nucleation, followed by slow growth, and finally rapid dendritic growth with back-filling to form oscillatory zoning in rims. SPD analyses indicate that olivine and pyroxene crystals grew or accumulated in clusters rather than as randomly distributed grains. These data reveal complex solidification histories for Martian basalts, and are generally consistent with the formation at depth of olivine megacryst cores, which were entrained in ascending magmas that crystallized pyroxenes, small olivines, and oscillatory rims on megacrysts.

  3. Olivine-dominated asteroids: Mineralogy and origin

    NASA Astrophysics Data System (ADS)

    Sanchez, Juan A.; Reddy, Vishnu; Kelley, Michael S.; Cloutis, Edward A.; Bottke, William F.; Nesvorný, David; Lucas, Michael P.; Hardersen, Paul S.; Gaffey, Michael J.; Abell, Paul A.; Corre, Lucille Le

    2014-01-01

    Olivine-dominated asteroids are a rare type of objects formed either in nebular processes or through magmatic differentiation. The analysis of meteorite samples suggest that at least 100 parent bodies in the main belt experienced partial or complete melting and differentiation before being disrupted. However, only a few olivine-dominated asteroids, representative of the mantle of disrupted differentiated bodies, are known to exist. Due to the paucity of these objects in the main belt their origin and evolution have been a matter of great debate over the years. In this work we present a detailed mineralogical analysis of twelve olivine-dominated asteroids. We have obtained near-infrared (NIR) spectra (0.7-2.4 ?m) of asteroids (246) Asporina, (289) Nenetta, (446) Aeternitas, (863) Benkoela, (4125) Lew Allen and (4490) Bamberry. Observations were conducted with the Infrared Telescope Facility (IRTF) on Mauna Kea, Hawai'i. This sample was complemented with spectra of six other olivine-dominated asteroids including (354) Eleonora, (984) Gretia, (1951) Lick, (2501) Lohja, (3819) Robinson and (5261) Eureka obtained by previous workers. Within our sample we distinguish two classes, one that we call monomineralic-olivine asteroids, which are those whose spectra only exhibit the 1 ?m feature, and another referred to as olivine-rich asteroids, whose spectra exhibit the 1 ?m feature and a weak (Band II depth ˜4%) 2 ?m feature. For the monomineralic-olivine asteroids the olivine chemistry was found to range from ˜Fo49 to Fo70, consistent with the values measured for brachinites and R chondrites. In the case of the olivine-rich asteroids we determined their olivine and low-Ca pyroxene abundance using a new set of spectral calibrations derived from the analysis of R chondrites spectra. We found that the olivine abundance for these asteroids varies from 0.68 to 0.93, while the fraction of low-Ca pyroxene to total pyroxene ranges from 0.6 to 0.9. A search for dynamical connections between the olivine-dominated asteroids and asteroid families found no genetic link (of the type core-mantel-crust) between these objects.

  4. Nanostructured materials for lithium-ion batteries: Surface conductivity vs. bulk

    E-print Network

    Ryan, Dominic

    Nanostructured materials for lithium-ion batteries: Surface conductivity vs. bulk ion cathode materials for high capacity lithium-ion batteries. Owing to their inherently low electronic-ion batteries. Lithium transition metal phosphates such as LiFePO4,1 LiMnPO4,2 Li3V2(PO4)3 3 and LiVPO4F4 have

  5. An experimental investigation of olivine morphology

    NASA Technical Reports Server (NTRS)

    Donaldson, C. H.

    1976-01-01

    Results are reported for a morphological study of olivine and an experimental investigation performed to determine the degrees of supercooling and the cooling rates necessary to crystallize particular morphologies. Ten arbitrary categories of three-dimensional olivine crystal shape are identified: polyhedral, granular, hopper, chain, lattice, plate, branching, radiate, feather, and swallow-tail. The morphological study establishes that equant and tabular crystals are the common shapes of olivine, nonequant crystals are elongate parallel to the a or c axis, and skeletal crystals result when a particular form is missing or only partially developed. In the experiment, olivine crystals were grown by melting rock samples above their liquidus temperatures before initiating crystallization. The results show that olivine morphology changes systematically as a function of the degree of melt supercooling, the melt cooling rate, and the normative olivine and water contents of the melt. It is also found that each shape has a specific range of temperature stability which is essentially independent of melt composition.

  6. Aligned Olivine in the Springwater Pallasite

    NASA Astrophysics Data System (ADS)

    Fowler-Gerace, N.; Tait, K.; Moser, D.; Barker, I.; Tian, B. Y.

    2014-12-01

    The mechanism by which olivine grains became embedded within iron-nickel alloy in pallasite meteorites continues to be a matter of scientific debate. Geochemical and textural observations have failed to fully elucidate the origin and history of the olivine crystals; however, little research attention has been devoted to their crystallographic orientations within the metal matrix. Klosterman and Buseck [1] found no crystallographic preferred orientation of olivine in nine pallasites, but the Leitz five-axis universal stage method imposed limitations on precision (estimated within ˜4?) and sample size (only 10 crystals were measured in the Springwater pallasite, for instance). Using Electron Backscatter Diffraction, we have collected crystallographic orientation data (accurate to ±0.5? [2]) for 343 crystals within ˜65 cm2 sample surface from Springwater. Though no global crystallographic preferred orientation exists, very low misorientations are observed among [100] axes of olivine crystals within specific texturally-defined domains. Combined with our thorough characterization of large-scale Springwater textures, the definitively non-random spatial distribution of olivine orientations reveals the nature of the olivine's initial formation environment as well as the sequence of events subsequent to metal incorporation. [1] Klosterman and Buseck. 1973. J Geophys Res 78(32):7581-7588. [2] Oxford Instruments. 2013. http://www.ebsd.com/.

  7. Atom Probe Tomography of Olivine

    NASA Astrophysics Data System (ADS)

    Parman, S. W.; Gorman, B.; Jackson, C.; Cooper, R. F.; Jaeger, D.

    2010-12-01

    Here we present atom probe tomographic (APT) analyses of natural olivine. APT provides three-dimensional trace element and isotopic analysis with sub-nanometer spatial resolution. It has been used for many years in engineering and materials science, but has not been applied to geological materials because traditional APT can only be used on conducting (usually metal) samples. The recent development of laser assisted APT has changed this situation, and now semi-conductors and insulators can be analyzed (Marquis et al., 2009, Kelly et al 2007). Potentially, this opens APT to extensive use in geoscience as many Fe-bearing silicates are semi-conductors. In this study, we explore the capability of the new class of APT instrumentation to analyze geological materials. APT involves the controlled evaporation of small, cylindrical specimens (100's nm in diameter) within an electric field. Specimens are typically prepared using in-situ focused-ion-beam (FIB) liftout and shaping techniques. Evaporated atoms are accelerated to a detector plate that records the position of the atom with sub-nm precision. Evaporated atoms are measured using time-of-flight mass spectrometry, allowing both elemental and isotopic determination. Since the method progressively ablates into the needle, the final analytical result is a nm-scale 3-dimensional image in which the position and identity of each detected atom is known. Typical mass resolution is between 200 and 1200 (full-width at half maximum) and typical concentration detection limits are 10 ppm. The number of potential applications of APT to igneous, metamorphic and sedimentary materials is large, ranging from studies of mineral and melt inclusions, to fine scale layering in minerals, to reaction surfaces and diffusion profiles. Much recent progress in the geochemical and petrologic fields has been driven by the increasing spatial resolution of the ion probe and laser ablation ICPMS. The ability of APT to provide atom-scale mass spectrometry should continue this trend. The main limitations to atom probe analysis of geological materials are the ability to control heat flow during laser pulsing and the associated ability to control clustering during field evaporation. Both of these factors can be controlled through specimen preparation and varying the atom probe experimental factors. Olivine specimens were properly analyzed using laser pulsed APT through the use of shallow (nominally 1mm) FIB liftouts and wide shank angle specimen apices. APT settings were found to give the best mass resolution using low specimen temperatures, 0.2 nJ laser energy, and 50 kHz pulse repetition rate. Increasing any of these values increases the amount of thermal tails due to excessive heat buildup, reducing the mass spectrum resolution, and ultimately affecting the spatial resolution of the reconstruction. Marquis EA, Miller MK, Blavette D, Ringer SP, Sudbrack CK and Smith DW (2009). MRS Bulletin 34: 725-730. Thomas F. Kelly, David J. Larson, Keith Thompson, Roger L. Alvis, Joseph H. Bunton, Jesse D. Olson, Brian P. Gorman, Ann. Rev. Mat. Res. 37: 681-727.

  8. Diffusion of highly charged cations in olivine

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Watson, E. B.; Liang, Y.

    2012-12-01

    Diffusion of tungsten, titanium and phosphorus have been measured in natural iron-bearing olivine (~Fo90) and synthetic forsterite. Experiments were run under buffered conditions (with iron-wustite or Ni-NiO buffers) in 1-atm furnaces. The sources of diffusant for experiments were MgWO4 for tungsten diffusion, Mg2TiO4 for Ti diffusion, and AlPO4 for P diffusion; in all cases these compounds were pre-reacted at high temperature with Mg2SiO4 or Fe-bearing olivine prior to diffusion anneals. Samples were placed with the source materials in noble metal or silica capsules, which were sealed under vacuum in silica glass ampoules with solid buffers. Rutherford backscattering spectrometry (RBS) was used to measure depth profiles for all sets of experiments; measurements of P were also made with Nuclear Reaction Analysis using the 31P(?,p)34S reaction. These new data suggest marked differences among diffusivities of these cations, with titanium diffusion faster than diffusion of tungsten, but slower than diffusion of phosphorus over the conditions investigated. Diffusivities of all of these elements appear significantly slower than those of divalent cations in olivine. These results will be discussed in context with extant diffusion data for major, trace and minor elements in olivine. The effects of oxygen fugacity and olivine composition on diffusion, and potential implications for diffusion mechanisms will also be considered.

  9. Shock-produced olivine glass - First observation

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.; Ahrens, T. J.; Lally, J. S.; Nord, G. L., Jr.; Christie, J. M.; Heuer, A. H.

    1977-01-01

    Transmission electron microscope (TEM) observations of an experimentally shock-deformed single crystal of natural peridot, /Mg(0.88)Fe(0.12)/2SiO4, recovered from peak pressures of about 56 billion pascals revealed the presence of amorphous zones located within crystalline regions with a high density of tangled dislocations. This is the first reported observation of olivine glass. The shocked sample exhibits a wide variation in the degree of shock deformation on a small scale, and the glass appears to be intimately associated with the highest density of dislocations. This study suggests that olivine glass may be formed as a result of shock at pressures above about 50 to 55 billion pascals and that further TEM observations of naturally shocked olivines may demonstrate the presence of glass.

  10. The origin of ferrous zoning in Allende chondrule olivines

    NASA Technical Reports Server (NTRS)

    Peck, Julia A.; Wood, John A.

    1987-01-01

    Very similar major and minor element compositions are noted in the ferrous olivine occurring in chondrules at olivine grain boundaries, along cracks in olivine grains, interleaved with enstatite, and in the inner portions of exposed olivine grain surface rims; simultaneous formation by a single process is therefore suggested. The ferrous chondrule olivine probably formed by the reaction of chondrules with very hot nebular vapors over a period of several hours, followed by the condensation of residual metal vapors onto those olivine surfaces that were in direct contact with the gas as the system cooled. The ferrous chondrule olivine that occurs interleaved with enstatite in Allende does not have a composition idendical to, and is not the precursor of, matrix olivine.

  11. Olivine, and the Origin of Kimberlite N. T. ARNDT1

    E-print Network

    Tommasi, Andrea

    Olivine, and the Origin of Kimberlite N. T. ARNDT1Ã , M. GUITREAU2 , A.-M. BOULLIER3 , A. LE ROEX4 ADVANCE ACCESS PUBLICATION JANUARY 12, 2010 Two types of olivine occur in kimberlites from Greenland or polycrystal- line aggregates that are a common constituent of many kimberlites. Olivine compositions

  12. Barred olivine chondrules in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Weisberg, Michael K.

    1987-01-01

    The characteristics of 125 barred olivine chondrules identified in polished thin sections of 26 H-L-LL3-6 chondrites were studied, using an electron microprobe for determining mineral abundances and a broad-beam electron microprobe for determining bulk compositions. Compared with all chondrule types in the H-L-LL3 ordinary chondrites, the barred olivine chondrules were found to be enriched in FeO, Al2O3, Na2O, and K2O and depleted in SiO2 and MgO; they were also found to be enriched in the feldspathic component. It is concluded that the precursor components of barred olivine chondrules consisted of a mixture of an olivine-rich component, a refractory-rich component containing Al2O3, TiO2, and CaO, and a volatile-rich alkalic component. This unusual combination implies high temperatures of melting for the refractory component and low temperatures for the volatile component, supporting the hypothesis of Grossman and Wasson (1983) that the alkalies condensed on the alumina already available.

  13. Transmission electron microscopy of subsolidus oxidation and weathering of olivine

    USGS Publications Warehouse

    Banfield, J.F.; Veblen, D.R.; Jones, B.F.

    1990-01-01

    Olivine crystals in basaltic andesites which crop out in the Abert Rim, south-central Oregon have been studied by high-resolution and analytical transmission electron microscopy. The observations reveal three distinct assemblages of alteration products that seem to correspond to three episodes of olivine oxidation. The olivine crystals contain rare, dense arrays of coherently intergrown Ti-free magnetite and inclusions of a phase inferred to be amorphous silica. We interpret this first assemblage to be the product of an early subsolidus oxidation event in the lava. The second olivine alteration assemblage contains complex ordered intergrowths on (001) of forsterite-rich olivine and laihunite (distorted olivine structure with Fe3+ charge balanced by vacancies). Based on experimental results for laihunite synthesis (Kondoh et al. 1985), these intergrowths probably formed by olivine oxidation between 400 and 800??C. The third episode of alteration involves the destruction of olivine by low-temperature hydrothermal alteration and weathering. Elongate etch-pits and channels in the margins of fresh olivine crystals contain semi-oriented bands of smectite. Olivine weathers to smectite and hematite, and subsequently to arrays of oriented hematite crystals. The textures resemble those reported by Eggleton (1984) and Smith et al. (1987). We find no evidence for a metastable phase intermediate between olivine and smectite ("M" - Eggleton 1984). The presence of laihunite exerts a strong control on the geometry of olivine weathering. Single laihunite layers and laihunite-forsteritic olivine intergrowths increase the resistance of crystals to weathering. Preferential development of channels between laihunite layers occurs where growth of laihunite produced compositional variations in olivine, rather than where coherency-strain is associated with laihunite-olivine interfaces. ?? 1990 Springer-Verlag.

  14. Mechanisms of electrical conductivity in olivine

    SciTech Connect

    Schock, R.N.; Duba, A.G.; Shankland, T.J.

    1984-01-01

    Data on the electrical conductivity and the thermoelectric effect in single crystals indicate that the charge conduction mechanism in pure magnesium forsterite is electrons. The concentration of electrons can be varied by controlling the number of oxygen vacancies through manipulation of the oxygen pressure. For iron bearing olivine, the conduction mechanism is by electron holes localized on an iron ion. Since iron strongly affects the creep process as well, oxidation of iron is probably accompanied by the production of magnesium vacancies. 15 references.

  15. Exploring exogenic sources for the olivine on Asteroid (4) Vesta

    NASA Astrophysics Data System (ADS)

    Le Corre, Lucille; Reddy, Vishnu; Sanchez, Juan A.; Dunn, Tasha; Cloutis, Edward A.; Izawa, Matthew R. M.; Mann, Paul; Nathues, Andreas

    2015-09-01

    The detection of olivine on Vesta is interesting because it may provide critical insights into planetary differentiation early in our Solar System's history. Ground-based and Hubble Space Telescope (HST) observations of Asteroid (4) Vesta have suggested the presence of olivine on the surface. These observations were reinforced by the discovery of olivine-rich HED meteorites from Vesta in recent years. However, analysis of data from NASA's Dawn spacecraft has shown that this "olivine-bearing unit" is actually impact melt in the ejecta of Oppia crater. The lack of widespread mantle olivine, exposed during the formation of the 19 km deep Rheasilvia basin on Vesta's South Pole, further complicated this picture. Ammannito et al. (Ammannito, E. et al. [2013a]. Nature 504, 122-125) reported the discovery of local scale olivine-rich units in the form of excavated material from the mantle using the Visible and InfraRed spectrometer (VIR) on Dawn. These sites are concentrated in the walls and ejecta of craters Arruntia (10.5 km in diameter) and Bellicia (41.7 km in diameter), located in the northern hemisphere, 350-430 km from Rheasilvia basin's rim. Here we explore alternative sources for the olivine in the northern hemisphere of Vesta by reanalyzing the data from the VIR instrument using laboratory spectral measurements of meteorites. Our rationale for using the published dataset was to bypass calibration issues and ensure a consistent dataset between the two studies. Our analysis of the VIR data shows that while the interpretation of their spectra as an olivine-rich unit is correct, the nature and origin of that olivine could be more complicated. We suggest that these olivine exposures could also be explained by the delivery of olivine-rich exogenic material. This hypothesis is supported by meteoritical evidence in the form of exogenic xenoliths containing significant amount of olivine in some of the HED meteorites from Vesta. Previous laboratory work on HEDs show that potential sources of olivine on Vesta could be different types of olivine-rich meteorites, either primitive achondrites (acapulcoites, lodranites, ureilites), ordinary chondrites (H, L, LL), pallasites, or carbonaceous chondrites (e.g., CV). Based on our spectral band parameters analysis, the lack of correlation between the location of these olivine-rich terrains and possible mantle-excavating events, and supported by observations of HED meteorites, we propose that a probable source for the olivine seen in the northern hemisphere corresponds to remnants of impactors made of olivine-rich meteorites. The best curve-matching results with laboratory spectra suggest these units are HED material mixed with either ordinary chondrites, or with some olivine-dominated meteorites such as R-chondrites.

  16. Search for Olivine Spectral Signatures on the Surface of Vesta

    NASA Technical Reports Server (NTRS)

    Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

    2012-01-01

    The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of groundbased and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta s surface in the wavelength range from 0.25 to 5.1 m during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes, olivines and their mixtures.

  17. Shock effects in olivine and implications for Hugoniot data

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.

    1980-01-01

    New observations of shock deformation in single-crystal olivine are presented for the range in peak pressures from about 16 to 75 GPa. A nonequilibrium model is suggested for the behavior of olivine under shock which explains the densification associated with a mixed-phase region and which is consistent with all available observations, yet which bears little similarity to the equilibrium behavior of olivine at high pressure.

  18. Water and Carbon Dioxide Adsorption at Olivine Surfaces

    SciTech Connect

    Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

    2013-11-14

    Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

  19. A scanning electron microscope study of olivine crystal surfaces

    NASA Technical Reports Server (NTRS)

    Olsen, E. J.; Grossman, L.

    1974-01-01

    SEM photographs were taken of euhedral olivine grains from the Murchison C2 chondrite and several terrestrial and lunar occurrences. In general, the crystal faces of the meteorite grains are rough and uneven, with irregular growth patterns. They are very similar to crystal faces on terrestrial olivine grains that formed by sublimation from a vapor phase. They are very different from the relatively smooth and featureless surfaces of magmatic olivine crystals that precipitated from igneous melts. Qualitatively, the surface morphology of the crystal supports the contention that many euhedral crystals of olivine in C2 meteorites condensed from a gas phase.

  20. Vaporization Studies of Olivine via Knudsen Effusion Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Costa, G. C. C.; Jacobson, N. S.

    2014-01-01

    Olivine is the major mineral in the Earth's upper mantle occurring predominantly in igneous rocks and has been identified in meteorites, asteroids, the Moon and Mars. Among many other important applications in planetary and materials sciences, the thermodynamic properties of vapor species from olivine are crucial as input parameters in computational modelling of the atmospheres of hot, rocky exoplanets (lava planets). There are several weight loss studies of olivine vaporization in the literature and one Knudsen Effusion Mass Spectrometry (KEMS) study. In this study, we examine a forsterite-rich olivine (93% forsterite and 7% fayalite, Fo93Fa7) with KEMS to further understand its vaporization and thermodynamic properties.

  1. Discovery of Olivine in the Nili Fossae Region of Mars

    USGS Publications Warehouse

    Hoefen, T.M.; Clark, R.N.; Bandfield, J.L.; Smith, M.D.; Pearl, J.C.; Christensen, P.R.

    2003-01-01

    We have detected a 30,000-square-kilometer area rich in olivine in the Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of grabens and fractures related to the formation of the Isidis impact basin. We propose that post-impact faulting of this area has exposed subsurface layers rich in olivine. Linear mixture analysis of Thermal Emission Spectrometer spectra shows surface exposures of 30% olivine, where the composition of the olivine ranges from Fo30 to Fo70.

  2. Diffusive Fractionation of Lithium Isotopes in Olivine

    NASA Astrophysics Data System (ADS)

    Homolova, V.; Richter, F. M.; Watson, E. B.; Chaussidon, M.

    2014-12-01

    Systematic lithium isotope variations along concentration gradients found in olivine and pyroxene grains from terrestrial, lunar and martian rocks have been attributed to diffusive isotopic fractionation [Beck et al., 2006; Tang et al., 2007]. In some cases, these isotopic excursions are so large that a single grain may display isotopic variability that spans almost the entire range of documented terrestrial values [Jeffcoate et al., 2007]. In this study, we present the results of experiments to examine diffusive isotopic fractionation of lithium in olivine. The experiments comprised crystallographically oriented slabs of San Carlos olivine juxtaposed with either spodumene powder or a lithium rich pyroxene crystal. Experiments were conducted at 1 GPa and 0.1MPa over a temperature range of 1000 to 1125?C. Oxygen fugacity in the 0.1MPa experiments was controlled using the wustite-magnetite and nickel-nickel oxide solid buffer assemblages. Lithium concentrations generally decrease smoothly away from the edges of the grains; however, experiments involving diffusion parallel to the a-axis consistently show peculiar wavy or segmented concentration profiles. Lithium diffusivity parallel to the c-axis is on the order of 1E-14m2/s at 1100?C. The diffusivity parallel to the c-axis is more than an order of magnitude faster than diffusion parallel to the b-axis and correlates positively with oxygen fugacity. The lithium isotopic composition, ?7Li = 1000‰ * ((?7Lisample- ?7Ligrain center)/ ?7Ligrain center), shows a decrease away from the edge of the grain to a minimum value (up to 70‰ lighter) and then an abrupt increase back to the initial isotopic composition of the olivine grain. This isotopic profile is similar to those found in natural grains and an experimental study on diffusive fractionation of lithium isotopes in pyroxene [Richter et al., 2014]. Results from the present study are modeled using the approach of Dohmen et al. [2010], which assumes lithium diffusion occurs on both a metal and interstitial site and that lithium is able to jump between these two sites. The best fits to the results show that diffusive isotopic fractionation may occur on both the interstitial and metal site but the degree of diffusive isotopic fractionation is always greater on the interstitial site.

  3. Mineralogical Comparison of Olivine in Shergottites and A Shocked L Chondrite: Implications for Shock Histories of Brown Olivine

    NASA Technical Reports Server (NTRS)

    Takenouchi, A.; Mikouchi, T.; Yamaguchi, A.; Zolensky, M. E.

    2015-01-01

    Most Martian meteorites are heavily shocked, exhibiting numerous shock features, for example undulatory extinction of olivine and pyroxene, the presence of diaplectic glass ("maskelynite") and the formation of shock melt. Among these shock features, olivine darkening ("brown" olivine) is unique in Martian meteorites because no other meteorite group shows such a feature. Although the presence of brown olivine in shergottites was reported thirty years ago, detailed observation by TEM has not been performed until the NWA 2737 chassignite was discovered, whose olivine is darkened, being completely black in hand specimen. Fe metal nano-particles were found in NWA 2737 olivine which are considered to have been formed by olivine reduction during heavy shock. Subsequently, magnetite nano-particles were also found in other Martian meteorites and the coexistence of Fe metal and magnetite nano-particles was reported in the NWA 1950 shergottite and some Fe metal nano-particles were mantled by magnetite. Therefore, the formation process of nano-particles seems to be complex. Because "brown" olivine is unique to Martian meteorites, they have a potential to constrain their shock conditions. In order to better understand the shock history of Martian meteorites, we compared olivine in several shergottites with that in a highly-shocked L chondrite which contains ringwoodite.

  4. THE ORIGIN OF BROWN OLIVINE IN MARTIAN DUNITE C. M. Pieters1

    E-print Network

    Hiroi, Takahiro

    Carlos Olivine 45-90 µm [EAC] Human Eye Sensitivity Chassigny Olivine Coarse RGB NWA2737 Olivine 45 the visible through the near-infrared part of the spectrum are shown to be due to nano- phase metallic iron

  5. Fast grain growth of olivine in liquid Fe-S and the formation of pallasites with rounded olivine grains

    NASA Astrophysics Data System (ADS)

    Solferino, Giulio F. D.; Golabek, Gregor J.; Nimmo, Francis; Schmidt, Max W.

    2015-08-01

    Despite their relatively simple mineralogical composition (olivine + Fe-Ni metal + FeS ± pyroxene), the origin of pallasite meteorites remains debated. It has been suggested that catastrophic mixing of olivine fragments with Fe-(Ni)-S followed by various degrees of annealing could explain pallasites bearing solely or prevalently fragmented or rounded olivines. In order to verify this hypothesis, and to quantify the grain growth rate of olivine in a liquid metal matrix, we performed a series of annealing experiments on natural olivine plus synthetic Fe-S mixtures. The best explanation for the observed olivine grain size distributions (GSD) of the experiments are dominant Ostwald ripening for small grains followed by random grain boundary migration for larger grains. Our results indicate that olivine grain growth in molten Fe-S is significantly faster than in solid, sulphur-free metal. We used the experimentally determined grain growth law to model the coarsening of olivine surrounded by Fe-S melt in a 100-600 km radius planetesimal. In this model, an impact is responsible for the mixing of olivine and Fe-(Ni)-S. Numerical models suggest that annealing at depths of up to 50 km allow for (i) average grain sizes consistent with the observed rounded olivine in pallasites, (ii) a remnant magnetisation of Fe-Ni olivine inclusions as measured in natural pallasites and (iii) for the metallographic cooling rates derived from Fe-Ni in pallasites. This conclusion is valid even if the impact occurs several millions of years after the differentiation of the target body was completed.

  6. Ringwoodite lamellae in olivine: Clues to olivine–ringwoodite phase transition mechanisms in shocked meteorites and subducting slabs

    PubMed Central

    Chen, Ming; Goresy, Ahmed El; Gillet, Philippe

    2004-01-01

    The first natural occurrence of ringwoodite lamellae was found in the olivine grains inside and in areas adjacent to the shock veins of a chondritic meteorite, and these lamellae show distinct growth mechanism. Inside the veins where pressure and temperature were higher than elsewhere, ringwoodite lamellae formed parallel to the {101} planes of olivine, whereas outside they lie parallel to the (100) plane of olivine. The lamellae replaced the host olivine from a few percent to complete. Formation of these lamellae relates to a diffusion-controlled growth of ringwoodite along shear-induced planar defects in olivine. The planar defects and ringwoodite lamellae parallel to the {101} planes of olivine should have been produced in higher shear stress and temperature region than that parallel to the (100) plane of olivine. This study suggests that the time duration of high pressure and temperature for the growth of ringwoodite lamellae might have lasted at least for several seconds, and that an intracrystalline transformation mechanism of ringwoodite in olivine could favorably operate in the subducting lithospheric slabs in the deep Earth. PMID:15479764

  7. Cotectic proportions of olivine and spinel in olivine-tholeiitic basalt and evaluation of pre-eruptive processes

    USGS Publications Warehouse

    Roeder, P.; Gofton, E.; Thornber, C.

    2006-01-01

    The volume %, distribution, texture and composition of coexisting olivine, Cr-spinel and glass has been determined in quenched lava samples from Hawaii, Iceland and mid-oceanic ridges. The volume ratio of olivine to spinel varies from 60 to 2800 and samples with >0.02% spinel have a volume ratio of olivine to spinel of approximately 100. A plot of wt % MgO vs ppm Cr for natural and experimental basaltic glasses suggests that the general trend of the glasses can be explained by the crystallization of a cotectic ratio of olivine to spinel of about 100. One group of samples has an olivine to spinel ratio of approximately 100, with skeletal olivine phenocrysts and small (100 ??m) spinel crystals that show evidence of two stages of growth, and a volume ratio of olivine to spinel of 100 to well over 1000. The olivine and spinel in this group have crystallized more slowly with little physical interaction, and show evidence that they have accumulated in a magma chamber. ?? 2006 Oxford University Press.

  8. Olivine in the Southern Isidis Basin

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) took this observation of the transition region between Libya Montes and the Isidis Basin on Mars at 17:16 UTC (12:16 p.m. EST) on January 2, 2007, near 3.6 degrees north latitude, 84.1 degrees east longitude. The image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 18 meters (60 feet) across. The image is about 11 kilometers (7 miles) wide at its narrowest point.

    The Isidis Basin resulted from of a gigantic impact on the surface of Mars early in the planet's history. The southern rim, where this target is located, is a region of complex geology and part of the planetary dichotomy boundary that separates the older southern highlands from the lower, younger northern plains. The image on the left was constructed from three visible wavelengths (RGB: 0.71, 0.60, 0.53 microns) and is a close approximation of how the surface would appear to the human eye. The image on the right was constructed from three infrared wavelengths (RGB: 2.49, 1.52, 1.08 microns) chosen to highlight variations in the mineralogy of the area. Of interest is that features in this image not only differ in color, but also in texture and morphology. The gray areas absorb similarly at all wavelengths used in this image, but display absorptions at other wavelengths related to the iron- and magesium-rich mineral pyroxene. The reddest areas absorb strongly at the wavelengths used for green and blue, which is attributable to another iron- and magesium-rich mineral, olivine. The brownish areas show subdued mineral absorptions and could represent some type of mixture between the other two materials. The presence of the mineral olivine is particularly interesting because olivine easily weathers to other minerals; thus, its presence indicates either the lack of weathering in this region or relatively recent exposure.

    CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials -- leading to new understanding of the climate.

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

  9. Boron, beryllium, and lithium, partitioning in olivine

    SciTech Connect

    Neroda, Elizabeth

    1996-05-01

    A one atmosphere experimental study was performed to determine the mineral/melt partition coefficients for B, Be, and Li in forsteritic olivine. Two compositions were chosen along the 1350{degrees}C isotherm, 1b (Fo{sub 17.3} Ab{sub 82.7} An{sub 0} by weight) and 8c (Fo{sub 30} Ab{sub 23.3} An{sub 47.8}, by weight) were then combined in equal amounts to form a composition was doped with 25ppm Li, B, Yb, Nb, Zr, Sr, and Hf, 50ppm Sm, and 100ppm Be, Nd, Ce, and Rb. Electron and ion microprobe analyses showed that the olivine crystals and surrounding glasses were homogeneous with respect to major and trace elements. Partition coefficients calculated from these analyses are as follows: 1b: D{sub B} = 4.41 ({+-} 2.3) E-03, D{sub Be} = 2.86 ({+-} 0.45) E-03, D{sub Li} = 1.54 ({+-} 0.21) E-01, 50/50: D{sub B} = 2.86 ({+-} 0.5) E-03, D{sub Be} = 2.07 ({+-} 0.09) E-03, D{sub Li} = 1.51 ({+-} 0.18) E-01, 8c: D{sub B} = 6.05 ({+-} 1.5) E-03, D{sub Be} = 1.81 ({+-} 0.03) E-03, D{sub Li} = 1.31 ({+-} 0.09) E-01. The results of this study will combined with similar data for other minerals as part of a larger study to understand the partitioning behavior of B, Be, and Li in melting of the upper mantle at subduction zones.

  10. The olivine macrocryst problem: New insights from minor and trace element compositions of olivine from Lac de Gras kimberlites, Canada

    NASA Astrophysics Data System (ADS)

    Bussweiler, Yannick; Foley, Stephen F.; Prelevi?, Dejan; Jacob, Dorrit E.

    2015-04-01

    This study presents detailed petrographical and geochemical investigations on remarkably fresh olivines in kimberlites from the EKATI Diamond Mine™ located in the Tertiary/Cretaceous Lac de Gras kimberlite field within the Slave craton of Canada. Olivine, constituting about 42 vol.% of the analyzed samples, can be divided into two textural groups: (i) macrocrystic olivines, > 100 ?m sub-rounded crystals and (ii) groundmass olivines, < 100 ?m subhedral crystals. Olivines from both populations define two distinct chemical trends; a "mantle trend" with angular cores, showing low Ca (< 0.1 wt.% CaO) and high Ni (0.3-0.4 wt.% NiO) at varying Mg# (0.86-0.93), contrasts with a "melt trend" typified by thin (< 100 ?m) rims with increasing Ca (up to 1.0 wt.% CaO) and decreasing Ni (down to 0.1 wt.% NiO) contents at constant Mg# (~ 0.915). These findings are in agreement with recent studies suggesting that virtually all olivine is composed of xenocrystic (i.e. mantle-related) cores with phenocrystic (i.e. melt-related) overgrowths, thereby challenging the traditional view that the origin of kimberlitic olivine can be distinguished based on size and morphology. The two main trends can be further resolved into sub-groups refining the crystallization history of olivine; the mantle trend indicates a multi-source origin that samples the layered lithosphere below the Slave craton, whereas the melt trend represents multi-stage crystallization comprising a differentiation trend starting at mantle conditions and a second trend controlled by the crystallization of additional phases (e.g. chromite) and changing magma conditions (e.g. oxidation). These trends are also seen in the concentrations of trace elements not routinely measured in olivine (e.g. Na, P, Ti, Co, Sc, Zr). Trace element mapping with LA-ICP-MS reveals the distribution of these elements within olivine grains. The trace element distribution between the two trends appears to be consistent with phenocrystic olivine overgrowths mainly originating from dissolved orthopyroxene, showing enrichment in Zr, Ga, Nb, Sc, V, P, Al, Ti, Cr, Ca and Mn in the melt trend. In a sample of magmatic kimberlite from the Leslie pipe, the amount of xenocrystic and phenocrystic olivine is estimated to be around 23 vol.% and 19 vol.%, respectively. Subtraction of this xenocrystic olivine from the Leslie bulk composition, aimed at estimating the parental kimberlite melt, results in a minor decrease of Mg# (by about 0.01) and SiO2 content (by about 3 wt.%), whereas CaO increases (by about 3 wt.%).

  11. Experimental Reproduction of Olivine rich Type-I Chondrules

    NASA Technical Reports Server (NTRS)

    Smith, Robert K.

    2005-01-01

    Ordinary chondritic meteorites are an abundant type of stony meteorite characterized by the presence of chondrules. Chondrules are small spheres consisting of silicate, metal, and sulfide minerals that experienced melting in the nebula before incorporation into chondritic meteorite parent bodies. Therefore, chondrules record a variety of processes that occurred in the early solar nebula. Two common types of unequilibrated chondrules with porphyritic textures include FeO-poor (type I) and FeO-rich (type II) each subdivided into an A (SiO2-poor) and B (SiO2-rich) series. Type IA chondrules include those with high proportions of olivine phenocrysts (>80% olivine) and type IB chondrules include those with high proportions of pyroxene phenocrysts (<20% olivine). An intermediate composition, type IAB chondrules include those chondrules in which the proportion of olivine phenocrysts is between 20-80%. We conducted high-temperature laboratory experiments (melting at 1550 C) to produce type I chondrules from average unequilibrated ordinary chondrite (UOC) material mixed with small amounts of additional olivine. The experiments were conducted by adding forsteritic rich olivine (San Carlos olivine, Fo 91) to UOC material (GRO 95544) in a 30/70 ratio, respectively. Results of these high temperature experiments suggest that we have replicated type IA chondrule textures and compositions with dynamic crystallization experiments in which a heterogeneous mixture of UOC (GRO 95544) and olivine (San Carlos olivine) were melted at 1550 C for 1 hr. and cooled at 5-1000 C/hr using graphite crucibles in evacuated silica tubes to provide a reducing environment.

  12. Fluorine in Olivines from Plutonic, Extrusive, and Hypabyssal Suites

    NASA Astrophysics Data System (ADS)

    Guggino, S. N.; Hervig, R. L.; Bell, D. R.

    2007-12-01

    Fluorine contents in a wide range of naturally-occurring olivine grains were determined by secondary ion mass spectrometry (SIMS) using a Cs+ primary beam, detection of negative secondary ions and an auxiliary electron gun for charge neutralization. A range of minerals and glasses containing 3 to 1300 ppm F were used to calibrate the secondary ion signal. Matrix effects appear to be small, and because fluorine has a high electron affinity, sensitivity is high (sub-ppm). Olivines from the study by Simkin and Smith (J. Geol., 1970) were analyzed for their F contents and span a range of suites that include upper mantle xenoliths and kimberlites, plutonic intrusives, ophiolites, shallow hypabyssal picrites and teschenites, and extrusive alkaline and tholeiitic basalts. Overall, the olivines in this study show a range of F concentrations from 0.5 to 32 ppm. Olivines from high- pressure environments show the highest individual and average F values, however large variations are also observed in this suite. Mantle xenoliths from this sample collection show a maximum and average F value of 14 and 4.1 ppm, respectively, and one olivine from kimberlite contains 32 ppm F. Earlier analyses from our laboratory (Hervig and Bell, 2005 Fall AGU) show a larger range in F from mantle-derived olivines. Plutonic intrusives and ophiolites, including layered intrusives and cumulates, show a range of F contents from 0.5 to 15 ppm, with an average value of 4 ppm. Olivines from the Kiglapait layered intrusion, Labrador show F content increasing with degree of fractional crystallization until the P2O5 content of the rock begins to increase. At this point, F in olivine decreases, presumably indicating partitioning of F into apatite. In the Hawaiian suites studied, F in olivine was high (8-12 ppm) in evolved andesites and lower (1-8 ppm) in more primitive basalts. Hypabyssal suites include a peridotite dike from Skye, (F < 1 ppm), a chilled olivine dolerite from Bornaskitaig (F = 2 ppm), a picrite from Igdlorsuit, Greenland (F = 4 ppm), and a teschenite from Black Jack Sill, Australia (F = 1.5 ppm). Fluorine measurements on the Simkin and Smith olivines are consistent with earlier observations that F is highest in OH-rich olivines (i.e., upper mantle xenoliths in kimberlites; Hervig & Bell, AGU Fall Mtg 2005).

  13. Detection of new olivine-rich locations on Vesta

    NASA Astrophysics Data System (ADS)

    Palomba, Ernesto; Longobardo, Andrea; De Sanctis, Maria Cristina; Zinzi, Angelo; Ammannito, Eleonora; Marchi, Simone; Tosi, Federico; Zambon, Francesca; Capria, Maria Teresa; Russell, Christopher T.; Raymond, Carol A.; Cloutis, Edward A.

    2015-09-01

    The discovery of olivine on Vesta's surface by the VIR imaging spectrometer onboard the Dawn space mission has forced us to reconsider our views of Vestan petrogenetic models. Olivines were expected to be present in the interior of Vesta: in the mantle of a vertically layered body as invoked by the magma ocean models, or at the base (or within) the mantle-crust boundary as proposed by fractionation models. Olivines have been detected by VIR-Dawn in two wide areas near Arruntia and Bellicia, regions located in the northern hemisphere. Interestingly, these olivine-rich terrains are far from the Rheasilvia and the more ancient Veneneia basins, which are expected to have excavated the crust down to reach the mantle. In this work we present our attempts to identify other undetected olivine rich areas on Vesta by using spectral parameters sensitive to olivine such as the Band Area Ratio (BAR) and other specific parameters created for the detection of olivines on Mars (forsterite, fayalite and a generic olivine index). As a preliminary step we calibrated these parameters by means of VIS-IR spectra of different HED meteorite samples: behaviors versus sample grain size and albedo were analyzed and discussed. We selected the BAR and the Forsterite Index as the best parameters that can be used on Vesta. A cross-correlation analysis has been applied in order to detect olivine signature on the VIR hyperspectral cubes. These detections have then been confirmed by an anti-correlation analysis between the BAR and one of the olivine parameters, independent of the first method applied. In agreement with the recent discovery, Arruntia and Bellicia were found to be as the most olivine-rich areas, i.e. where the parameter values are strongest. In addition we detected 6 new regions, all but one located in the Vesta north hemisphere. This result confirms again that the old petrogenetic models cannot be straightforwardly applied to Vesta and should be reshaped in the view of these new detections. An alternative and very recent option can be represented by the model according to which surface "eruption" of material from the mantle, including olivine can reach the surface of Vesta.

  14. The case for a cognate, polybaric origin for kimberlitic olivines

    NASA Astrophysics Data System (ADS)

    Moore, Andy E.

    2012-01-01

    Kimberlitic olivines typically show a continuous range in size and texture rather than two discrete populations. The cores of small euhedral olivines commonly provide the template for the final crystal shape, which in turn closely matches morphologies produced by crystallization from a moderately under-cooled magma. Cores and edges of the majority of all olivines define a continuous compositional field, which can be interpreted in terms of Raleigh crystallization. Marked chemical gradients at the olivine margins are linked to rapid physico-chemical changes to the magma associated with loss of volatiles during the late stages of emplacement. Thus, rapid crystallization of groundmass olivines would deplete the magma in Ni, but increase Ca activity. The latter would be enhanced by decreasing pressure coupled with loss of CO 2 from the carbonate-bearing kimberlite magma. For mantle olivines and the most refractory olivines in kimberlites (~ Fo 94) to be in equilibrium with bulk rock compositions matching those of Mg-rich macrocrystic and aphanitic kimberlites (Mg# ~ 88) requires a mineral-melt Mg-Fe distribution coefficient of 0.47. This is well within the experimentally determined range for this distribution coefficient in carbonate-bearing systems. In southern African post-Gondwana alkaline pipe clusters, the average bulk rock Mg# and composition of the associated most Mg-rich olivine both decrease sympathetically from the interior to the continental margin, which is also consistent with a cognate origin for the olivines. A kimberlite magma following a plausible P-T trajectory relative to the CO 2/H 2O peridotite solidus would initially experience superheating, resulting in partial resorption of early-formed olivines that crystallized on the cool conduit walls. It would become supersaturated as it crossed the carbonated peridotite "ledge", resulting in tabular and hopper growth forms typical of euhedral olivine cores. With further ascent, the magma would once again become superheated, resulting in partial resorption of these cores. Thus, apparently complex textures and internal zonation patterns of kimberlitic olivines are predicted by a plausible magma P-T trajectory.

  15. Olivines from Kimberlites and Diamonds: Problem of Origin

    NASA Astrophysics Data System (ADS)

    Sobolev, N. V.; Sobolev, A. V.; Tomilenko, A. A.; Kovyazin, S. V.; Kuzmin, D. V.

    2011-12-01

    Mg-rich olivine Fo [100Mg/(Mg + Fe)] 85-94 is the principal mineral of kimberlites, peridotite xenoliths and diamond inclusions. It is completely altered in common kimberlites, however, it is absolutely fresh in a huge block from Udachnaya-East kimberlite in Yakutia (Russia). Pioneering studies of this unaltered kimberlite resulted in a discovery of high role of a mantle chlorine along with very low water content (Kamenetsky et al., 2004, Geology, 32: 845-848). Two olivine populations are distinguished, which are represented by oval-rounded unzoned or partly zoned xenocrysts of olivine I (more than 1 mm) and well defined zoned phenocrysts ( 0.05-1.0 mm) of olivine II (e.g. Kamenetsky et al., 2008, J.Petrol., 49: 823-839). The cores of olivine II are compositionally similar to olivine I with Mg# 86-94, but rims of olivine II and partly preserved rims of olivine I have constant Fo values about 89-90. We report here the results of major and minor elements analyses by EPMA of more than 300 grains of olivine I and olivine II, both of cores and rims by high precision approach (Sobolev et al., 2007, Science, 316: 412-417) to minor elements including Ti, Al, Cr, Ca, Mn, Ni, Co using the high sample current and high counting time, which was found optimal to obtain limit of detection about 10 ppm. Several grains of analyzed olivines contain clinopyroxene (cpx) and pyrope (prp) inclusions confirming their high pressure origin. One large olivine I grain contains clusters of cpx ( 33 grains) and prp ( 6 grains) inclusions., having a range in Cr2O3 (1.52- 2.36 wt%) , Al2O3 (0.99-5.53 wt%) and Na2O (1.45-5.96 wt%) for cpx and Cr2O3 (3.51-4.42 wt%) and CaO (5.64-6.61 wt%) for prp, showing disequilibrium in olivine I core, containing 200 ppm Ti. This is completely different from any peridotite xenoliths, confirming the uniqueness of this assemblage. The systematic high Ti ( more than 150 ppm) of all studied cores of olivine grains containing low T (Ca# 43.3-48) cpx and prp inclusions confirm the listed differences from all olivines from peridotites and diamonds (e.g. Sobolev et al., 2009, Lithos, 112S: 701-713.). Earlier, similar Ti abundance was reported only for olivines from dunite nodules in Greenland kimberlites (e.g. Arndt et al., 2010, J. Petrol., 51: 573-602).We suggest that Ti-bearing olivine, represented more that 70% of studied samples, is a part of high pressure pyrope lherzolite assemblage, which was formed and grew during the formation and early evolution of kimberlites

  16. Olivine and Pyroxene Compositions in Fine-Grained Chondritic Materials

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Frank, D.

    2011-01-01

    Our analyses of the Wild-2 samples returned by the Stardust Mission have illuminated critical gaps in our understanding of related astromaterials. There is a very large database of olivine and low-calcium pyroxene compositions for coarse-grained components of chondrites, but a sparse database for anhydrous silicate matrix phases. In an accompanying figure, we present comparisons of Wild-2 olivine with the available chondrite matrix olivine major element data. We thus have begun a long-term project measuring minor as well as major element compositions for chondrite matrix and chondritic IDPs, and Wild 2 grains. Finally, we wish to re-investigate the changes to fine-grained olivine and low-Ca pyroxene composition with progressive thermal metamorphism. We have examined the LL3-4 chondrites which because of the Hayabusa Mission have become very interesting.

  17. Olivine Deposits Associated with Impact Basins and Craters on Mars

    NASA Astrophysics Data System (ADS)

    Ody, A.; Poulet, F.; Langevin, Y.; Gondet, B.; Bibring, J.; Carter, J.

    2011-12-01

    An analysis of the 1?m olivine spectral signature applied to the entire and final OMEGA dataset [1] shows numerous olivine-bearing deposits in the 3 main basins of Mars (Argyre, Isidis and Hellas). These signatures are among the strongest of Mars, which suggests compositions with higher iron content and/or larger grain size and/or larger abundance than the ones of widespread olivine-bearing deposits observed on large parts of the southern highlands [1]. A spectral modeling based on a radiative transfer model [2] indicates that their compositions are still close to the forsterite one with abundance in the range of [15,40%] and grain sizes of a few hundreds of ?m. These deposits are exclusively localized on Noachian terrains. Distribution of these deposits around Argyre basin clearly takes the form of discontinuous patches of olivine-bearing rocks on the basin terrace, which strongly suggest that their formation is related to the basin formation event. Recent numerical simulations of basin formation show that impact that formed the Argyre basin could have excavated upper mantle materials and emplaced discontinuous patches of melted mantle on the basin terraces [3]. The observed olivine deposits in Argyre are thus interpreted as olivine-bearing material excavated from the upper mantle during the impact. Olivine deposits distribution around the Hellas basin is not as clear as for Argyre because of young resurfacing processes that strongly affected its region. Olivine deposits are fewer and mainly localized on the northern terrace of Hellas. Most of them are detected in crater ejecta, while a few similar to Argyre olivine discontinuous patches are also observed suggesting that a mantle origin as for Argyre is possible. Olivine has been detected by several datasets in the Nili Fossae region and in the south of Isidis basin. The spectral modeling of OMEGA spectra indicates an olivine abundance of about 40% and megacrysts of several millimeters for the region of Nili Fossae [2]. Several plausible hypotheses has been discussed to explain this unusual concentration of olivine-rich outcrops in Nili Fossae assuming three possibilities for their emplacement relative to the formation of the Isidis basin : pre-impact [4,5], contemporaneous [6], or post-impact [7]. The pretty unique settings and compositions of these deposits in comparison to the two other major basins indicate a different origin, with the post-impact one as the preferred one. Other several localized exposures with strong olivine signature are also found throughout the southern highlands and the northern plains mostly associated with craters. Olivine-bearing material is found in craters floors but also in some crater ejecta implying the presence of an olivine-rich underlying layer. Of special interest are some craters totally filled by olivine-rich lava lakes, which could have erupted through local (impact-related) fractures. [1] A. Ody et al. (2011) LPSC XXXXII.[2] F. Poulet et al. (2009), Icarus 201, 84-101.[3] Stewart S. (2010) AGU, San Francisco, abstract #P43A-08. [4] Hoefen et al. (2003) Science,302,627-630.[5] Hamilton and Christensen (2005), Geology,33,433-436.[6]J.F. Mustard et al. (2007), JGR, 112, E08S03.[7] L.L Tornabene et al. (2008), JGR, 113, E10001.

  18. The Microstructure of a Micrometeorite Impact into Lunar Olivine

    NASA Astrophysics Data System (ADS)

    Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

    2015-11-01

    Through TEM analysis of the cross-section of a ~20 µm diameter crater into an olivine single crystal we can see first-hand the effects of a single impact, including the creation of nanophase iron in the melt.

  19. Olivine Weathering: Abiotic Versus Biotic Processes as Possible Biosignatures

    NASA Technical Reports Server (NTRS)

    Longazo, T. G.; Wentworth, S. J.; McKay, D. S.; Southam, G.; Clemett, S. J.

    2001-01-01

    A preliminary study to determine how abiotic versus biotic processes affect the weathering of olivine crystals. Perhaps the differences between these weathering processes could be used as biosignatures. Additional information is contained in the original extended abstract.

  20. Systematics of Vanadium in Olivine from Planetary Basalts

    NASA Technical Reports Server (NTRS)

    Karner, J. M.; Papike, J. J.; Shearer, C. K.

    2002-01-01

    The systematics of vanadium in olivines from the Earth, Moon and Mars allows for the comparison of planetary basalt origin and igneous setting and process. Additional information is contained in the original extended abstract.

  1. Kamacite and olivine in ordinary chondrites - Intergroup and intragroup relationships

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.

    1990-05-01

    Results are presented from high-precision electron microprobe analyses of olivine and kamacite in a suite of 134 ordinary chondrites (OCs). The compositional ranges of these phases are defined for each OC group (high total Fe, low total Fe, and low total Fe/low metallic Fe). Anomalous OCs that have olivine and/or kamacite compositions that lie outside the established ranges are identified. The phases in the chondritic clasts of the Netschaevo iron meteorite are characterized to determine the relationship between Netschaevo and OCs. Intragroup variations of olivine and kamacite compositions with petrologic type are examined and OCs that contain olivine and/or kamacite grains with aberrant compositions are identified as fragmental breccias. Also, a search for new metallic Fe-Ni phases with extreme compositions is conducted. As a result of these analyses, several meteorites are reclassified.

  2. Aluminum speeds up the hydrothermal alteration of olivine

    NASA Astrophysics Data System (ADS)

    Andreani, Muriel; Daniel, Isabelle; Pollet-Villard, Marion

    2014-05-01

    The reactivity of ultramafic rocks toward hydrothermal fluids controls chemical fluxes at the interface between the internal and external reservoirs of silicate planets. On Earth, hydration of ultramafic rocks is ubiquitous and operates from deep subduction zones to shallow lithospheric environments where it considerably affects the physical and chemical properties of rocks and can interact with the biosphere. This process also has key emerging societal implications, such as the production of hydrogen as a source of carbon-free energy. To date, the chemical model systems used to reproduce olivine hydrothermal alteration lead to the formation of serpentine with sluggish reaction rates. Although aluminum is common in geological environments and in hydrothermal systems in particular, its role in serpentinization or olivine dissolution has not been investigated under hydrothermal conditions. Nevertheless, abundant Al supply is expected in fluids released from dehydration of metapelites in subduction zones as well as during the hydrothermal alteration of gabbros at mid-ocean ridges. Aluminum was also abundant in primitive environments of both the Earth and Mars, stored in either Al-rich minerals like plagioclase or Al-enriched ultramafic lavas. We have investigated the role of Al on the hydrothermal alteration of olivine in a series of experiments performed in a low-pressure diamond anvil cell while following the reaction progress in situ by optical imaging and Raman spectroscopy. Experiments were run for 4.5 to 7.5 days with two olivine grains reacted in saline water (0.5 molal NaCl) at 200°C and 300°C, and P=200 MPa. After two days, olivine crystals were fully transformed to an aluminous serpentine, also enriched in iron. The presence of Al in the hydrothermal fluid increases the rate of olivine serpentinization by more than one order of magnitude by enhancing olivine solubility and serpentine precipitation. The mechanism responsible for this increased solubility has to be further investigated but this result motivates a re-evaluation of the natural rates of olivine serpentinization and of olivine hydrolysis in general in a wide range of settings where olivines or peridotites are intimately associated with Al-providers. Such a fast reaction rate may affect the contribution of reaction-enhanced processes at the micrometer-scale, such as reaction-driven cracking, already proposed for enhancing serpentinization or carbonation of olivine. The effect of Al on lower crust and upper mantle metasomatism is expected to be even stronger at higher pressure in subduction zones where those reactions control the rheology and physical properties of the subducting plate and mantle wedge.

  3. Dissolution of olivine in basaltic liquids: experimental observations and applications.

    USGS Publications Warehouse

    Thornber, C.R.; Huebner, J.S.

    1985-01-01

    Rates of olivine dissolution in synthetic lunar basalt 77115 and a silica-enriched 77115 composition (Sil-77115) at superliquidus temperatures have been determined. Dissolution-rate data have been applied to the problem of the thermal history of fragment-laden impact-melt rocks of the lunar highlands. Textural and chemical criteria are discussed for the recognition of olivine resorption (and growth) phenomena in igneous rocks. -J.A.Z.

  4. Galapagos Plume Source Lithology : Implications from Olivine Phenocryst Compositions C. Vidito ,C. Herzberg and D.Geist

    E-print Network

    Geist, Dennis

    83844, USA. Ca (ppm) Mn (ppm) Fe/Mn (ppm) Ni (ppm) Mg-Number Mg-Number Olivines Peridotite Derivative Magmas (13-20% MgO) Olivines Peridotite Derivative Magmas (8-13% MgO) Olivines Peridotite Primary Magmas (8-38% MgO) Olivine Phenocryst Composition Fertile Peridotite Source (3.45% CaO) Olivine Phenocryst

  5. Olivine and pyroxene from the mantle of asteroid 4 Vesta

    NASA Astrophysics Data System (ADS)

    Lunning, Nicole G.; McSween, Harry Y.; Tenner, Travis J.; Kita, Noriko T.; Bodnar, Robert J.

    2015-05-01

    A number of meteorites contain evidence that rocky bodies formed and differentiated early in our solar system's history, and similar bodies likely contributed material to form the planets. These differentiated rocky bodies are expected to have mantles dominated by Mg-rich olivine, but direct evidence for such mantles beyond our own planet has been elusive. Here, we identify olivine fragments (Mg# = 80-92) in howardite meteorites. These Mg-rich olivine fragments do not correspond to an established lithology in the howardite-eucrite-diogenite (HED) meteorites, which are thought to be from the asteroid 4 Vesta; their occurrence in howardite breccias, combined with diagnostic oxygen three-isotope signatures and minor element chemistry, indicates they are vestan. The major element chemistry of these Mg-rich olivines suggests that they formed as mantle residues, in crustal layered intrusions, or in Mg-rich basalts. The trace element chemistry of these Mg-rich olivines supports an origin as mantle samples, but other formation scenarios could be possible. Interpreted as mantle samples, the range of Mg-rich olivine compositions indicates that Vesta's structure differs from that predicted by conventional models: Vesta has a chemically heterogeneous mantle that feeds serial magmatism. The range of olivine major element chemistries is consistent with models of an incompletely melted mantle such as in the model proposed by Wilson and Keil (2013) rather than a whole-mantle magma ocean for Vesta. Trace element chemistries of Mg-rich pyroxenes (Mg# = 85-92) provide support that some of these pyroxenes may represent initial fractional crystallization of mantle partial melts.

  6. Determining the composition of olivine on asteroidal surfaces

    NASA Technical Reports Server (NTRS)

    Sunshine, Jessica M.; Pieters, Carle M.

    1993-01-01

    Olivine was remotely identified as a major component on many S- and A-type asteroids based on qualitative analyses of broad absorption features near 1.0 micron in their telescopic reflectance spectra. Laboratory studies showed that this diagnostic olivine absorption feature is composed of three individual absorption bands resulting from electronic transitions of Fe(+2) in distorted M1 and M2 sites. Both the overall absorption feature and each of the individual absorption bands are also known to vary systematically as a function of olivine composition. Thus, it should be possible to remotely determine the composition of olivine present on the surfaces of the various olivine-rich asteroids. However, extrapolation of laboratory studies to compositional interpretation of asteroid spectra is complicated by several factors: observational noise; lower spectral resolution; compositional heterogeneities (including the presence of other phases such as pyroxenes and/or metal); and the effects of alteration processes. In order to address such complex problems, a quantitative approach to spectral analysis, the modified Gaussian model (MGM) was developed by Sunshine et al., which deconvolves spectra into their constituent absorption bands. The MGM, a refinement of the Gaussian model, more accurately adheres to the physical processes involved in electronic transition absorptions. Under the MGM, each spectrum is modeled in log reflectance and energy as a sum of absorption bands superimposed onto a baseline or continuum. Each absorption band is described by three model parameters (center, width, and strength) which can be interpreted and used to infer composition. One of the strengths of the MGM is that it allows compositional information to be extracted directly from measured spectra and is therefore complementary to other approaches to modeling asteroid spectra which require the use of meteorites and/or terrestrial samples as spectral analogs. A quantitative understanding of the properties of olivine absorptions was established by using the MGM to analyze a laboratory suite of spectra spanning a full range of olivine compositions.

  7. Extraction of in situ cosmogenic 14C from olivine

    USGS Publications Warehouse

    Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay

    2010-01-01

    Chemical pretreatment and extraction techniques have been developed previously to extract in situ cosmogenic radiocarbon (in situ 14C) from quartz and carbonate. These minerals can be found in most environments on Earth, but are usually absent from mafic terrains. To fill this gap, we conducted numerous experiments aimed at extracting in situ 14C from olivine ((Fe,Mg)2SiO4). We were able to extract a stable and reproducible in situ 14C component from olivine using stepped heating and a lithium metaborate (LiBO2) flux, following treatment with dilute HNO3 over a variety of experimental conditions. However, measured concentrations for samples from the Tabernacle Hill basalt flow (17.3 ?? 0.3 ka4) in central Utah and the McCarty's basalt flow (3.0 ?? 0.2 ka) in western New Mexico were significantly lower than expected based on exposure of olivine in our samples to cosmic rays at each site. The source of the discrepancy is not clear. We speculate that in situ 14C atoms may not have been released from Mg-rich crystal lattices (the olivine composition at both sites was ~Fo65Fa35). Alternatively, a portion of the 14C atoms released from the olivine grains may have become trapped in synthetic spinel-like minerals that were created in the olivine-flux mixture during the extraction process, or were simply retained in the mixture itself. Regardless, the magnitude of the discrepancy appears to be inversely proportional to the Fe/(Fe+Mg) ratio of the olivine separates. If we apply a simple correction factor based on the chemical composition of the separates, then corrected in situ 14C concentrations are similar to theoretical values at both sites. At this time, we do not know if this agreement is fortuitous or real. Future research should include measurement of in situ 14C concentrations in olivine from known-age basalt flows with different chemical compositions (i.e. more Fe-rich) to determine if this correction is robust for all olivine-bearing rocks. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.

  8. Tracing Oxygen Fugacity in Asteroids and Meteorites Through Olivine Composition

    NASA Technical Reports Server (NTRS)

    Sunshine, J. M.; Bus, S. J.; Burbine, T. H.; McCoy, T. J.

    2005-01-01

    Olivine absorptions are known to dominate telescopic spectra of several asteroids. Among the meteorite collection, three groups (excluding Martian meteorites), the pallasites, brachinites, and R group chondrites are plausible analogs to olivine-rich asteroids in that they are dominated by olivine. These meteorite groups have distinct petrologic origins. The primitive achondrite brachinites (which include both depleted and undeleted subgroups) are products of relatively minor differentiation and evolved in oxidizing environments. R chondrites are also thought to have formed in high oxygen states, but are closely related to ordinary chondrites (yet with their own distinct compositions and oxygen isotopic signatures). In contrast, pallasites, widely thought to be mantle components from much more evolved bodies, formed in more reducing environments. Petrologic indicators that are identifiable in spectral data must be used in order to infer the petrologic history of asteroids from surveys of their actual population. As discussed below, olivine composition (e.g. Fa#) can provide key constraints in exploring the origin and significance of olivine dominated asteroids.

  9. Olivine Composite Cathode Materials for Improved Lithium Ion Battery Performance

    SciTech Connect

    Ward, R.M.; Vaughey, J.T.

    2006-01-01

    Composite cathode materials in lithium ion batteries have become the subject of a great amount of research recently as cost and safety issues related to LiCoO2 and other layered structures have been discovered. Alternatives to these layered materials include materials with the spinel and olivine structures, but these present different problems, e.g. spinels have low capacities and cycle poorly at elevated temperatures, and olivines exhibit extremely low intrinsic conductivity. Previous work has shown that composite structures containing spinel and layered materials have shown improved electrochemical properties. These types of composite structures have been studied in order to evaluate their performance and safety characteristics necessary for use in lithium ion batteries in portable electronic devices, particularly hybrid-electric vehicles. In this study, we extended that work to layered-olivine and spinel-olivine composites. These materials were synthesized from precursor salts using three methods: direct reaction, ball-milling, and a coreshell synthesis method. X-ray diffraction spectra and electrochemical cycling data show that the core-shell method was the most successful in forming the desired products. The electrochemical performance of the cells containing the composite cathodes varied dramatically, but the low overpotential and reasonable capacities of the spinel-olivine composites make them a promising class for the next generation of lithium ion battery cathodes.

  10. Grain boundary diffusion in olivine (Invited)

    NASA Astrophysics Data System (ADS)

    Marquardt, K.; Dohmen, R.

    2013-12-01

    Olivine is the main constituent of Earth's upper mantle. The individual mineral grains are separated by grain boundaries that have very distinct properties compared to those of single crystals and strongly affect large-scale physical and chemical properties of rocks, e.g. viscosity, electrical conductivity and diffusivity. Knowledge on the grain boundary physical and chemical properties, their population and distribution in polycrystalline materials [1] is a prerequisite to understand and model bulk (rock) properties, including their role as pathways for element transport [2] and the potential of grain boundaries as storage sites for incompatible elements [3]. Studies on selected and well characterized single grain boundaries are needed for a detailed understanding of the influence of varying grain boundaries. For instance, the dependence of diffusion on the grain boundary structure (defined by the lattice misfit) and width in silicates is unknown [2, 4], but limited experimental studies in material sciences indicate major effects of grain boundary orientation on diffusion rates. We characterized the effect of grain boundary orientation and temperature on element diffusion in forsterite grain boundaries by transmission electron microscopy (TEM).The site specific TEM-foils were cut using the focused ion beam technique (FIB). To study diffusion we prepared amorphous thin-films of Ni2SiO4 composition perpendicular to the grain boundary using pulsed laser deposition. Annealing (800-1450°C) leads to crystallization of the thin-film and Ni-Mg inter-diffuse into the crystal volume and along the grain boundary. The inter-diffusion profiles were measured using energy dispersive x-ray spectrometry in the TEM, standardized using the Cliff-Lorimer equation and EMPA measurements. We obtain volume diffusion coefficients that are comparable to Ni-Mg inter-diffusion rates in forsterite determined in previous studies at comparable temperatures, with similar activation energies. Grain boundary diffusion perpendicular to the dislocation lines of the small angle grain boundaries proved to be about an order of magnitude faster than volume diffusion, whereas diffusion in high angle grain boundaries is several orders of magnitude faster. We will discuss the variation of element diffusion rates with grain boundary orientation and the temperature- and/or time-induced transition from one diffusion regime to the next regime. This is done using time series experiments and two-dimensional grain boundary diffusion simulations. Finally, we will debate the differences between our data and other data sets that result from different experimental setups, conditions and analyses.

  11. Effect of Mineralogy on the Rheological Properties of Olivine, Othopyroxene and Olivine/Orthopyroxene Mixtures at High Temperature and Pressure

    NASA Astrophysics Data System (ADS)

    Homburg, J. M.; Mei, S.; Kohlstedt, D. L.

    2013-12-01

    To better understand the influence of mineralogy on the rheological properties of the upper mantle, we have carried out a series of triaxial compressive creep experiments on olivine/orthopyroxene mixtures under high pressures (~6 GPa) and high temperatures (1373 - 1473 K) under anhydrous conditions. Experiments were performed using the deformation-DIA (D-DIA) apparatus on beamline X17B2 at the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of three mineralogical compositions (olivine, orthopyroxene and 50:50 volumetric ratio of olivine:orthopyroxene) were prepared from fine-grained (~10 ?m) mineral separates of San Carlos olivine and orthopyroxene. Orthopyroxene and olivine/orthopyroxene samples were cold pressed to attain a cylinder ~1 mm in length and 1.1 mm in diameter. The cold pressed sample was then stacked with a hot-pressed olivine sample of similar size and assembled with alumina pistons, a boron nitride sleeve and graphite resistance heater into a 6.2-mm edge length cubic pressure medium. Nickel disks were placed at the ends of both samples to act as strain markers. During each experiment, in-situ stress and strain measurements were obtained from X-ray diffraction and radiography, respectively. After annealing the samples at the pressure/temperature conditions of deformation for ~2 hours to insure compaction of the cold pressed sample, experiments were conducted at constant strain rates between 2.2x10^-5 and 3.3x10^-5 s^-1 up to axial strains of 5 to 20%. The orthopyroxene and olivine/orthopyroxene mixture deformed at approximately the same rate with the mixed phase system displaying some weakening relative to the single-phase system. This observation suggests that orthopyroxene may be controlling sample behavior in the mixed phase material. In contrast, the orthopyroxene and olivine/orthopyroxene samples crept ~ 2 - 3 times faster than olivine. This contrast in rheological behavior was observed at lower temperatures/higher differential stresses but not at higher temperatures/lower differential stresses, indicating that the weakening effect of orthopyroxene may be temperature dependent. Alternatively, this behavior may be due to grain size variations between the hot pressed and cold pressed samples; more work needs to be done to better constrain this possibility. Taken together, these findings suggest that variations in orthopyroxene content may significantly alter the rheological behavior of the upper mantle providing an important constraint for future geodynamic models of upper mantle behavior.

  12. Applicability of Henry's Law to helium solubility in olivine

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Parman, S. W.; Kelley, S. P.; Cooper, R. F.

    2013-12-01

    Applicability of Henry's Law to helium solubility in olivine We have experimentally determined helium solubility in San Carlos olivine across a range of helium partial pressures (PHe) with the goal of quantifying how noble gases behave during partial melting of peridotite. Helium solubility in olivine correlates linearly with PHe between 55 and 1680 bar. This linear relationship suggests Henry's Law is applicable to helium dissolution into olivine up to 1680 bar PHe, providing a basis for extrapolation of solubility relationships determined at high PHe to natural systems. This is the first demonstration of Henry's Law for helium dissolution into olivine. Averaging all the data of the PHe series yields a Henry's coefficient of 3.8(×3.1)×10-12 mol g-1 bar-1. However, the population of Henry's coefficients shows a positive skew (skewness = 1.17), i.e. the data are skewed to higher values. This skew is reflected in the large standard deviation of the population of Henry's coefficients. Averaging the median values from each experiment yields a lower Henry's coefficient and standard deviation: 3.2(× 2.3)×10-12 mol g-1 bar-1. Combining the presently determined helium Henry's coefficient for olivine with previous determinations of helium Henry's coefficients for basaltic melts (e.g. 1) yields a partition coefficient of ~10-4. This value is similar to previous determinations obtained at higher PHe (2). The applicability of Henry's Law here suggests helium is incorporated onto relatively abundant sites within olivine that are not saturated by 1680 bar PHe or ~5×10-9 mol g-1. Large radius vacancies, i.e. oxygen vacancies, are energetically favorable sites for noble gas dissolution (3). However, oxygen vacancies are not abundant enough in San Carlos olivine to account for this solubility (e.g. 4), suggesting the 3x10-12 mol g-1 bar-1 Henry's coefficient is associated with interstitial dissolution of helium. Helium was dissolved into olivine using an externally heated pressure vessel (Brown University). The starting materials were prepared by cutting gem-quality San Carlos olivine (~Fo90) into small blocks (~4×2×1 mm) using a diamond wafering blade saw and polishing with alumina slurries and colloidal silica. Analysis was completed by laser ablation-mass spectrometry using a 193 nm excimer laser and a MAP 215-50 specifically tuned for He (Open University, UK). Laser ablation pit depth varied from 2 to 40 ?m, and no correlation between pit depth and [He] is observed after accounting for variations PHe across the different experiments. This lack of correlation indicates a close approach to equilibrium was achieved over the experimental durations. Two analyses yielded spuriously high [He] (>3 std. dev. from the population mean, n = 85), and these analyses were not used to calculate Henry's coefficients. The two spuriously high analyses, in combination with the right skew of Henry's coefficients calculated from individual data points, suggests gem-quality San Carlos olivine contains volumes with anomalously high helium solubility. The nature of these volumes is currently under investigation. However, despite their presence, helium is still highly incompatible in olivine during partial melting. [1] Lux GCA 1987 [2] Heber et al. GCA 2007 [3] Shcheka & Keppler Nature 2012 [4] Walker et al. PEPI 2009

  13. Barred olivine 'chondrules' in lunar spinel troctolite 62295

    NASA Technical Reports Server (NTRS)

    Roedder, E.; Weiblen, P. W.

    1977-01-01

    Several objects have been found in sections of lunar igneous spinel troctolite 62295 that resemble certain meteoritic barred olivine chondrules. Each consists of an apparently spherical single crystal of Fo90 olivine, approximately 0.6-0.8 mm in diameter, containing a set of approximately 30-40 subparallel stringers of An95 plagioclase, whereas the stringers in ordinary meteoritic chondrules consist of glass. The olivine of the 62295 chondrules is also more magnesian, and is radially zoned, having a relatively iron-rich core and rim and an iron-poor intermediate zone. Several possible origins are proposed: impact-generated melt globules solidified in flight, spherical phenocrysts, and meteoritic chondrules, but none of these seems adequate to explain the detailed observations.

  14. An olivine-free mantle source of Hawaiian shield basalts.

    PubMed

    Sobolev, Alexander V; Hofmann, Albrecht W; Sobolev, Stephan V; Nikogosian, Igor K

    2005-03-31

    More than 50 per cent of the Earth's upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent with a deep olivine-bearing source, because this mineral together with pyroxene buffers both nickel and silicon at lower levels. This can be resolved if the olivine of the mantle peridotite is consumed by reaction with melts derived from recycled oceanic crust, to form a secondary pyroxenitic source. Our modelling shows that more than half of Hawaiian magmas formed during the past 1 Myr came from this source. In addition, we estimate that the proportion of recycled (oceanic) crust varies from 30 per cent near the plume centre to insignificant levels at the plume edge. These results are also consistent with volcano volumes, magma volume flux and seismological observations. PMID:15800614

  15. Exogenic olivine on Vesta from Dawn Framing Camera color data

    NASA Astrophysics Data System (ADS)

    Nathues, Andreas; Hoffmann, Martin; Schäfer, Michael; Thangjam, Guneshwar; Le Corre, Lucille; Reddy, Vishnu; Christensen, Ulrich; Mengel, Kurt; Sierks, Holger; Vincent, Jean-Baptist; Cloutis, Edward A.; Russell, Christopher T.; Schäfer, Tanja; Gutierrez-Marques, Pablo; Hall, Ian; Ripken, Joachim; Büttner, Irene

    2015-09-01

    In this paper we present the results of a global survey of olivine-rich lithologies on (4) Vesta. We investigated Dawn Framing Camera (FC) High Altitude Mapping Orbit (HAMO) color cubes (?60 m/pixel resolution) by using a method described in Thangjam et al. (Thangjam, G., Nathues, A., Mengel, K., Hoffmann, M., Schäfer, M., Reddy, V., Cloutis, E.A., Christensen, U., Sierks, H., Le Corre, L., Vincent, J.-B, Russell, C.T. [2014b]. Meteorit. Planet. Sci. arXiv:1408.4687 [astro-ph.EP]). In total we identified 15 impact craters exhibiting olivine-rich (>40 wt.% ol) outcrops on their inner walls, some showing olivine-rich material also in their ejecta and floors. Olivine-rich sites are concentrated in the Bellicia, Arruntia and Pomponia region on Vesta's northern hemisphere. From our multi-color and stratigraphic analysis, we conclude that most, if not all, of the olivine-rich material identified is of exogenic origin, i.e. remnants of A- or/and S-type projectiles. The olivine-rich lithologies in the north are possibly ejecta of the ?90 km diameter Albana crater. We cannot draw a final conclusion on their relative stratigraphic succession, but it seems that the dark material (Nathues, A., Hoffmann, M., Cloutis, E.A., Schäfer, M., Reddy, V., Christensen, U., Sierks, H., Thangjam, G.S., Le Corre, L., Mengel, K., Vincent, J.-B., Russell, C.T., Prettyman, T., Schmedemann, N., Kneissl, T., Raymond, C., Gutierrez-Marques, P., Hall, I. Büttner, I. [2014b]. Icarus (239, 222--237)) and the olivine-rich lithologies are of a similar age. The origin of some potential olivine-rich sites in the Rheasilvia basin and at crater Portia are ambiguous, i.e. these are either of endogenic or exogenic origin. However, the small number and size of these sites led us to conclude that olivine-rich mantle material, containing more than 40 wt.% of olivine, is basically absent on the present surface of Vesta. In combination with recent impact models of Veneneia and Rheasilvia (Clenet, H., Jutzi, M., Barrat, J.-A., Gillet, Ph. [2014]. Lunar Planet Sci. 45, #1349; Jutzi, M., Asphaug, E., Gillet, P., Barrat, J.-A., Benz, W. [2013]. Nature 494, 207-210), which predict an excavation depth of up to 80 km, we are confident that the crust-mantle depth is significantly deeper than predicted by most evolution models (30 km; Mittlefehldt, D.W. [2014]. Asteroid 4 Vesta: A Fully Differentiated Dwarf Planet. NASA Technical Reports Server (20140004857.pdf)) or, alternatively, the olivine-content of the (upper) mantle is lower than our detection limit, which would lead to the conclusion that Vesta's parent material was already depleted in olivine compared to CI meteorites.

  16. Grinding methods to enhance the reactivity of olivine

    SciTech Connect

    Summers, Cathy A.; Dahlin, David C.; Rush, Gilbert E.; O'Connor, William K.; Gerdemann, Stephen J.

    2004-01-01

    The Albany Research Center (ARC) conducted studies of mechanical activation by conventional and ultra-fine grinding techniques to enhance olivine reactivity in mineral carbonation reactions. Activated olivine is one of several solid feed materials used at ARC in reactions with carbon dioxide to form carbonate minerals. This paper compares grinding techniques via energy demand data and product characteristics, including particle size distributions, surface areas, full width at half maximum (FWHM) XRD analyses, and particle morphology by SEM analyses. Reactivity was gauged by percent conversion to carbonate in subsequent carbonation tests.

  17. A Survey of Olivine Alteration Products Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Kuebler, K.; Jolliff, B. L.; Wang, A.; Haskin, L. A.

    2004-01-01

    Identification of mineral alteration products will aid in the crucial task of interpreting past Martian environmental conditions, especially aqueous environments. Olivine has been identified at the surface of Mars and is readily altered in aqueous environments. Using Raman spectroscopy, we studied three rocks with altered olivine and compared the data with mineral chemistry from electron microprobe analysis. Although the alteration in all three samples has loosely been called iddingsite their appearances and modes of occurrences differ as described. Alteration products in all three samples are likely fine-grained mixtures.

  18. Comparison of LiFePO4 from different sources

    SciTech Connect

    Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat; Newman, John

    2004-06-21

    The lithium iron phosphate chemistry is plagued by the poor conductivity and slow diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study, we obtained LiFePO{sub 4} powders and/or electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from 0.4% to 15% ''in-situ'' carbon. In addition, particle sizes varied by as much as an order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of having a distribution in particle sizes, and ideas for making materials in order to maximize the power capability of this chemistry.

  19. Petrogenesis of olivine-phyric shergottite Larkman Nunatak 06319: Implications for enriched components in martian basalts

    E-print Network

    Kah, Linda

    Petrogenesis of olivine-phyric shergottite Larkman Nunatak 06319: Implications for enriched-phyric shergottite Larkman Nunatak (LAR) 06319. The meteorite is porphyritic, consisting of megacrysts of olivine (62

  20. Carbonate mineralization in percolated olivine aggregates: Linking effects of crystallographic orientation and fluid flow

    E-print Network

    Cattin, Rodolphe

    , and magnesite, were precipitated on olivine surfaces. The results showed that the dissolution of olivine in the percolated rock. They are mainly located along the moderate (for dolomite) and the minor (for magnesite) flow

  1. B-type olivine fabric and mantle wedge serpentinization beneath the Ryukyu arc

    E-print Network

    B-type olivine fabric and mantle wedge serpentinization beneath the Ryukyu arc Kimberly McCormack,1. Long (2013), B-type olivine fabric and mantle wedge serpentinization beneath the Ryukyu arc, Geophys

  2. Chemical zonation in olivine-hosted melt inclusions

    NASA Astrophysics Data System (ADS)

    Newcombe, M. E.; Fabbrizio, A.; Zhang, Youxue; Ma, C.; Le Voyer, M.; Guan, Y.; Eiler, J. M.; Saal, A. E.; Stolper, E. M.

    2014-07-01

    Significant zonation in major, minor, trace, and volatile elements has been documented in naturally glassy olivine-hosted melt inclusions from the Siqueiros Fracture Zone and the Galapagos Islands. Components with a higher concentration in the host olivine than in the melt (e.g., MgO, FeO, Cr2O3, and MnO) are depleted at the edges of the zoned melt inclusions relative to their centers, whereas except for CaO, H2O, and F, components with a lower concentration in the host olivine than in the melt (e.g., Al2O3, SiO2, Na2O, K2O, TiO2, S, and Cl) are enriched near the melt inclusion edges. This zonation is due to formation of an olivine-depleted boundary layer in the adjacent melt in response to cooling and crystallization of olivine on the walls of the melt inclusions, concurrent with diffusive propagation of the boundary layer toward the inclusion center. Concentration profiles of some components in the melt inclusions exhibit multicomponent diffusion effects such as uphill diffusion (CaO, FeO) or slowing of the diffusion of typically rapidly diffusing components (Na2O, K2O) by coupling to slow diffusing components such as SiO2 and Al2O3. Concentrations of H2O and F decrease toward the edges of some of the Siqueiros melt inclusions, suggesting either that these components have been lost from the inclusions into the host olivine late in their cooling histories and/or that these components are exhibiting multicomponent diffusion effects. A model has been developed of the time-dependent evolution of MgO concentration profiles in melt inclusions due to simultaneous depletion of MgO at the inclusion walls due to olivine growth and diffusion of MgO in the melt inclusions in response to this depletion. Observed concentration profiles were fit to this model to constrain their thermal histories. Cooling rates determined by a single-stage linear cooling model are 150-13,000 °C h-1 from the liquidus down to ~1,000 °C, consistent with previously determined cooling rates for basaltic glasses; compositional trends with melt inclusion size observed in the Siqueiros melt inclusions are described well by this simple single-stage linear cooling model. Despite the overall success of the modeling of MgO concentration profiles using a single-stage cooling history, MgO concentration profiles in some melt inclusions are better fit by a two-stage cooling history with a slower-cooling first stage followed by a faster-cooling second stage; the inferred total duration of cooling from the liquidus down to ~1,000 °C ranges from 40 s to just over 1 h. Based on our observations and models, compositions of zoned melt inclusions (even if measured at the centers of the inclusions) will typically have been diffusively fractionated relative to the initially trapped melt; for such inclusions, the initial composition cannot be simply reconstructed based on olivine-addition calculations, so caution should be exercised in application of such reconstructions to correct for post-entrapment crystallization of olivine on inclusion walls. Off-center analyses of a melt inclusion can also give results significantly fractionated relative to simple olivine crystallization. All melt inclusions from the Siqueiros and Galapagos sample suites exhibit zoning profiles, and this feature may be nearly universal in glassy, olivine-hosted inclusions. If so, zoning profiles in melt inclusions could be widely useful to constrain late-stage syneruptive processes and as natural diffusion experiments.

  3. Influence of aluminum on the hydrothermal alteration rate of olivine

    NASA Astrophysics Data System (ADS)

    Andreani, M.; Daniel, I.; Pollet-Villard, M.

    2013-12-01

    The reactivity of ultramafic rocks under hydrothermal conditions controls chemical fluxes at the interface between the internal and external reservoirs of silicate planets. On Earth, hydration of ultramafic rocks is ubiquitous and operates from deep subduction zones to shallow lithospheric environments where it considerably affects the physical and chemical properties of rocks and can interact with the biosphere. This process also has key emerging societal implications, such as the production of hydrogen as a source of carbon-free energy. To date, the chemical model systems used to reproduce olivine hydrothermal alteration lead to the formation of serpentine with sluggish reaction rates. Although aluminum is common in geological environments and in hydrothermal systems in particular, its role in serpentinization or olivine dissolution has not been investigated under hydrothermal conditions. Nevertheless, abundant Al supply is expected in fluids released from dehydration of metapelites in subduction zones as well as during the hydrothermal alteration of gabbros at mid-ocean ridges. Aluminum was also abundant in primitive environments of both the Earth and Mars, stored in either Al-rich minerals like plagioclase or Al-enriched ultramafic lavas. We have investigated the role of Al on the hydrothermal alteration of olivine in a series of experiments performed in a low-pressure diamond anvil cell while following the reaction progress in situ by optical imaging and by confocal Raman spectroscopy. Experiments were run for 4.5 to 7.5 days with two olivine grains reacted in saline water (0.5 molal NaCl) at 200°C and 300°C, and P=200 MPa. After two days, olivine crystals were fully transformed to an aluminous serpentine, also enriched in iron. The very fast precipitation of serpentine may inhibit magnetite nucleation here. However, this does not rule out an H2 production since serpentines classically incorporate non negligible amount of ferric iron in their structure. The presence of Al in the hydrothermal fluid increases the rate of olivine serpentinization by more than one order of magnitude by increasing olivine solubility and enhancing serpentine precipitation. The mechanism responsible for this increased solubility has to be investigated further but this result motivates a re-evaluation of the natural rates of olivine serpentinization and of olivine hydrolysis in general in a wide range of settings where olivines or peridotites are intimately associated with Al-providers. Such a fast reaction rate may affect the contribution of reaction-enhanced processes at the micrometer-scale, such as reaction-driven cracking, already proposed for enhancing serpentinization or carbonation of olivine. The effect of Al on lower crust and upper mantle metasomatism is expected to be even stronger at higher pressure in subduction zones where those reactions control the rheology and physical properties of the subducting plate and mantle wedge. Finally, this study also provides a way to accelerate serpentinization reactions towards economically feasible time-scale and temperature for industrial H2 production and/or CO2 remediation.

  4. Trace Element Compositions of Pallasite Olivine Grains and Pallasite Origin

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Herrin, J. S.

    2010-01-01

    Pallasites are mixtures of metal with magnesian olivine. Most have similar metal compositions and olivine oxygen isotopic compositions; these are the main-group pallasites (PMG). The Eagle Station grouplet of pallasites (PES) have distinctive metal and olivine compositions and oxygen isotopic compositions. Pallasites are thought to have formed at the core-mantle boundary of their parent asteroids by mixing molten metal with solid olivine of either cumulatic or restitic origin. We have continued our investigation of pallasite olivines by doing in situ trace element analyses in order to further constrain their origin. We determined Al, P, Ca, Ga and first row transition element contents of olivine grains from suite of PMG and PES by LA-ICP-MS at JSC. Included in the PMG suite are some that have anomalous metal compositions (PMG-am) and atypically ferroan olivines (PMG-as). Our EMPA work has shown that there are unanticipated variations in olivine Fe/Mn, even within those PMG that have uni-form Fe/Mg. Manganese is homologous with Fe2+, and thus can be used the same way to investigate magmatic fractionation processes. It has an advantage for pallasite studies in that it is unaffected by redox exchange with the metal. PMG can be divided into three clusters on the basis of Mn/Mg; low, medium and high that can be thought of as less, typically and more fractionated in an igneous sense. The majority of PMG have medium Mn/Mg ratios. PMG-am occur in all three clusters; there does not seem to be any relationship between putative olivine igneous fractionation and metal composition. The PMG-as and one PMG-am make up the high Mn/Mg cluster; no PMG are in this cluster. The high Mn/Mg cluster ought to be the most fractionated (equivalent to the most Fe-rich in igneous suites), yet they have among the lowest contents of incompatible lithophile elements Al and Ti and the two PMG-as in this cluster also have low Ca and Sc contents. This is inconsistent with simple igneous fractionation on a single, initially homogeneous parent asteroid. For Al and Ti, the low and high Mn/Mg clusters have generally uniform contents, while the medium cluster has wide ranges. This is also true of analyses of duplicate grains from the medium cluster pallasites which can have very different Al and Ti contents. Those from the low and high clusters do not. These observations suggest that pallasite olivines are not cumulates, but rather are restites from high degrees of melting. The moderately siderophile elements P and Ga show wide ranges in the high Mn/Mg cluster, but very uniform compositions in the medium cluster, opposite the case for Al and Ti. There is no correlation of P or Ga and Fe/Mn as might be expected if redox processes controlled the contents of moderately siderophile elements in the olivines. The lack of correlation of P could reflect equilibration with phosphates, although there is no correlation of Ca with P as might be expected

  5. Amoeboid olivine aggregates from CH carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Park, Changkun; Nagashima, Kazuhide

    2014-08-01

    Amoeboid olivine aggregates (AOAs) in CH carbonaceous chondrites are texturally and mineralogically similar to those in other carbonaceous chondrite groups. They show no evidence for alteration and thermal metamorphism in an asteroidal setting and consist of nearly pure forsterite (Fa<3; in wt%, CaO = 0.1-0.8, Cr2O3 = 0.04-0.48; MnO < 0.5), anorthite, Al-diopside (in wt%, Al2O3 = 0.7-8.1; TiO2 < 1), Fe,Ni-metal, spinel, and, occasionally, low-Ca pyroxene (Fs1Wo2-3), and calcium-aluminum-rich inclusions (CAIs). The CAIs inside AOAs are composed of hibonite, grossite, melilite (Åk13-44), spinel, perovskite, Al,Ti-diopside (in wt%, Al2O3 up to 19.6; TiO2 up to 13.9), and anorthite. The CH AOAs, including CAIs within AOAs, have isotopically uniform 16O-rich compositions (average ?17O = -23.4 ± 2.3‰, 2SD) and on a three-isotope oxygen diagram plot along ?slope-1 line. The only exception is a low-Ca pyroxene-bearing AOA 1-103 that shows a range of ?17O values, from -24‰ to -13‰. Melilite, grossite, and hibonite in four CAIs within AOAs show no evidence for radiogenic 26Mg excess (?26Mg). In contrast, anorthite in five out of six AOAs measured has ?26Mg corresponding to the inferred initial 26Al/27Al ratio of (4.3 ± 0.7) × 10-5, (4.2 ± 0.6) × 10-5, (4.0 ± 0.3) × 10-5, (1.7 ± 0.2) × 10-5, and (3.0 ± 2.6) × 10-6. Anorthite in another AOA shows no resolvable ?26Mg excess; an upper limit on the initial 26Al/27Al ratio is 5 × 10-6. We infer that CH AOAs formed by gas-solid condensation and aggregation of the solar nebula condensates (forsterite and Fe,Ni-metal) mixed with the previously formed CAIs. Subsequently they experienced thermal annealing and possibly melting to a small degree in a 16O-rich gaseous reservoir during a brief epoch of CAI formation. The low-Ca pyroxene-bearing AOA 1-103 may have experienced incomplete melting and isotope exchange in an 16O-poor gaseous reservoir. The lack of resolvable ?26Mg excess in melilite, grossite, and hibonite in CAIs within AOAs reflects heterogeneous distribution of 26Al in the solar nebula during this epoch. The observed variations of the inferred initial 26Al/27Al ratios in anorthite of the mineralogically pristine and uniformly 16O-rich CH AOAs could have recorded (i) admixing of 26Al in the protoplanetary disk during the earliest stages of its evolution and/or (ii) closed-system Mg-isotope exchange between anorthite and Mg-rich minerals (spinel, forsterite, and Al-diopside) during subsequent prolonged (days-to-weeks) thermal annealing at high temperature (?1100 °C) and slow cooling rates (?0.01 K h-1) that has not affected their O-isotope systematics. The proposed thermal annealing may have occurred in an impact-generated plume invoked for the origin of non-porphyritic magnesian chondrules and Fe,Ni-metal grains in CH and CB carbonaceous chondrites about 5 Myr after formation of CV CAIs.

  6. Deformation microstructures of olivine in peridotite from Spitsbergen, Svalbard and implications for seismic anisotropy

    E-print Network

    Jung, Haemyeong

    Deformation microstructures of olivine in peridotite from Spitsbergen, Svalbard and implications in the peridotite of Spitsbergen were studied. Seismic anisotropy in the upper mantle can be explained mainly by the lattice- preferred orientation (LPO) of olivine. The LPOs of the olivine in the peridotites were

  7. Martian Dunite NWA 2737: Petrographic constraints on geological history, shock events, and olivine color

    E-print Network

    Treiman, Allan H.

    Martian Dunite NWA 2737: Petrographic constraints on geological history, shock events, and olivine two shock events. The first shock, to stage S5­S6, affected the olivine by producing in it planar­15 nm in diameter. At this stage the olivine became deeply colored, i.e., strongly absorbing at visible

  8. Evidence for equilibrium conditions during the partitioning of nickel between olivine and komatiite liquids.

    USGS Publications Warehouse

    Budahn, J.R.

    1986-01-01

    Olivine-liquid partition coefficients for Ni(DNi), calculated from Ni vs MgO abundance variations in komatiite series basalts, compare favourably with experimentally determined values, if Ni variations in olivine-controlled basalts can be modelled with an equation that assumes equilibrium between the entire olivine crystal and its coexisting liquid.-J.A.Z.

  9. Solar Radiation Management and Olivine Dissolution Methods in Climate Engineering

    NASA Astrophysics Data System (ADS)

    Kone, S.

    2014-12-01

    An overview of solar radiation management and olivine dissolution methods allows to discuss, comparatively, the benefits and consequences of these two geoengineering techniques. The combination of those two techniques allows to concomitantly act on the two main agents intervening in global warming: solar radiation and carbon dioxide. The earth surface temperature increases due mainly to carbon dioxide (a greenhouse gas) that keeps the solar radiation and causes the global warming. Two complementary methods to mitigate climate change are overviewed: SRM method, which uses injected aerosols, aims to reduce the amount of the inbound solar radiation in atmosphere; and olivine dissolution in water, a key chemical reaction envisaged in climate engineering , aiming to reduce the amount of the carbon dioxide in extracting it from atmosphere. The SRM method works on scenarios of solar radiation decrease and the olivine dissolution method works as a carbon dioxide sequestration method. Olivine dissolution in water impacts negatively on the pH of rivers but positively in counteracting ocean acidification and in transporting the silica in ocean, which has benefits for diatom shell formation.

  10. Petrogenesis of olivine-phyric shergottite Yamato 980459, revisited

    E-print Network

    and Physics Department, Washington University, St. Louis, MO 63130, USA Received 13 June 2007; accepted megacrysts have magnesian cores (Fo84­86) that appear to be in equilibrium with the Y-980459 whole-rock composition based on Fe­Mg partitioning. However, crystal size distribution (CSD) plots for Y-980459 olivines

  11. Deformation of olivine in torsion under hydrous conditions

    NASA Astrophysics Data System (ADS)

    Demouchy, Sylvie; Tommasi, Andréa; Barou, Fabrice; Mainprice, David; Cordier, Patrick

    2012-08-01

    We performed torsional deformation experiments on pre-hydrated fine-grained olivine aggregates using an innovative experimental assembly to investigate water weakening in mantle rocks at high shear strains. San Carlos olivine powder was cold-pressed and then hot-pressed under hydrous conditions, producing aggregates with average grain sizes of 7 or 15 ?m. Deformation experiments were performed in a high-resolution gas-medium apparatus equipped with a torsional actuator, under a confining pressure of 300 MPa, a temperature of 1200 °C, and constant shear strain rates ranging from 8 × 10-5 to 1.4 × 10-4 s-1. Maximum shear stresses range from 150 to 195 MPa. These values are 30% lower relative to those determined in previous torsion experiments on dry, fined-grained dunites under similar conditions. Textures and microstructures of the starting and deformed specimens were characterized by scanning and transmission electron microscopy. All deformed aggregates exhibit a shape-preferred orientation marking a foliation and lineation, as well as a reduction in mean grain size from 15 ?m down to 3-4 ?m due to dynamic recrystallization. Olivine crystallographic fabrics developed rapidly (? < 0.1), but their strength, characterized by the J-index, is low compared to naturally deformed peridotites or to polycrystalline olivine deformed at similar finite shear strains under dry conditions. The crystallographic fabrics are consistent with deformation by a dislocation accommodated creep mechanism with activation of multiple {0 k l}[1 0 0] systems, among which the (0 1 0)[1 0 0] slip system is dominant, and minor participation of the (0 1 0)[0 0 1] slip system. Transmission electron microscopy confirmed the occurrence of dislocations with [1 0 0] and [0 0 1] Burgers vectors in most grains. Analysis of unpolarized infrared spectra indicates that hydrogen concentration in the olivine lattice is below the saturation level of 18 ppm wt H2O, which is similar to those typically observed in spinel-bearing peridotite xenoliths, and also provide evidence for water-rich inter-granular material trapped in pores and grain boundaries. Seismic properties computed from the CPO observations correspond to those most commonly observed in naturally deformed mantle peridotites with fast P-wave propagation and S-wave polarization subparallel to the shear direction. These torsion experiments on fine-grained olivine polycrystals under hydrous conditions indicate that water weakening under lithospheric conditions is linked to various defects with hydrogen in the olivine structure, as well as with water-derived species in grain boundaries or pores.

  12. The effect of mineral paragenesis on Al diffusion in olivine

    NASA Astrophysics Data System (ADS)

    Zhukova, Irina; O'Neill, Hugh; Capbell, Ian

    2014-05-01

    Al is the most abundant trivalent impurity of olivine and is particularly important because its concentration in olivine is temperature dependant, and it therefore has potential as a geothermometer (Wan, et al. 2008). Furthermore recent studies show that the incorporation of water into the olivine lattice is affected by the presents of trivalent cations such as Al3+ (Berry, et al. 2007; Hauri, et al. 2006). The Al distribution in olivines from volcanic rocks is often zoned and mantle olivines may also show an inhomogeneous distribution of Al, whereas the majority of other trace elements homogenized by diffusion (Mallmann, et al. 2009; McKibbin, et al.). However, there are no quantitative experimental data for Al diffusion in olivine, probably because the combination of low concentration rate and low diffusion rate make measurement difficult. We investigated the effect of silica activity on the diffusion rate of Al in forsterite at varying temperatures using solid-state buffer assemblages. Our study aimed to quantify the effect of major cation activities on the diffusion and concentration of Al in forsterite and also provide insights into the mechanism of Al substitution into the olivine lattice. The activities of SiO2, MgO and Al2O3 were buffered in each experiment by four different mineral associations: forsterite + periclase + spinel (fo+per+sp); forsterite + spinel + sapphirine (fo+sp+spr); forsterite + sapphirine + cordierite (fo+spr+cor); forsterite + cordierite + enstatite (fo+cor+en). Iron oxide in proportion of FeO/(FeO+MgO) = 0.1 was added to mixtures for San Carlos olivine experiments. Diffusion experiments were performed at the one-atmosphere vertical tube furnaces modified to control the fO2 by CO-CO2 gas mixing or in a box furnace in air for 10 - 28 days at temperatures from 1100 to 1500oC and logfO2 -0.7 and -5.7. The experiment with the San Carlos olivine was performed at 1300oC and at logfO2 = -5.7. In order to obtain equilibrium concentrations of the point defects we performed some experiments with pre-annealing. Diffusion profiles were measured by LA-ICP-MS in a traverse mode. The Al content of forsterite decreases with temperature dependence, increasing the potential of Al in olivine as a geothermometer. We obtain the activation energy of 379 kJ/mol for the high aSiO2 experiments, which is close within error of the value of 364 kJ/mol for the low aSiO2 experiments implying a common diffusion mechanism. The pre-exponential factor, however, increases by 5 orders of magnitude from low aSiO2 (fo+per+sp buffer) to high aSiO2 (fo+cor+en buffer). The much higher diffusivity at high aSiO2 indicates that Al diffusion occurs through octahedral cation site vacancies.

  13. Geoengineering potential of artificially enhanced silicate weathering of olivine

    PubMed Central

    Köhler, Peter; Hartmann, Jens; Wolf-Gladrow, Dieter A.

    2010-01-01

    Geoengineering is a proposed action to manipulate Earth’s climate in order to counteract global warming from anthropogenic greenhouse gas emissions. We investigate the potential of a specific geoengineering technique, carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification, because it influences the global climate via the carbon cycle. If important details of the marine chemistry are taken into consideration, a new mass ratio of CO2 sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per year directly, if olivine is distributed as fine powder over land areas of the humid tropics, but this rate is limited by the saturation concentration of silicic acid. In our calculations for the Amazon and Congo river catchments, a maximum annual dissolution of 1.8 and 0.4 Pg of olivine seems possible, corresponding to the sequestration of 0.5 and 0.1 Pg of C per year, but these upper limit sequestration rates come at the environmental cost of pH values in the rivers rising to 8.2. Open water dissolution of fine-grained olivine and an enhancement of the biological pump by the rising riverine input of silicic acid might increase our estimate of the carbon sequestration, but additional research is needed here. We finally calculate with a carbon cycle model the consequences of sequestration rates of 1–5 Pg of C per year for the 21st century by this technique. PMID:21059941

  14. Diffusive over-hydration of olivine-hosted melt inclusions

    NASA Astrophysics Data System (ADS)

    Hartley, Margaret E.; Neave, David A.; Maclennan, John; Edmonds, Marie; Thordarson, Thor

    2015-09-01

    The pre-eruptive water content of magma is often estimated using crystal-hosted melt inclusions. However, olivine-hosted melt inclusions are prone to post-entrapment modification by H+ diffusion as they re-equilibrate with their external environment. This effect is well established for the case of H+ loss from olivine-hosted inclusions that have cooled slowly in degassed magma. Here we present evidence for the opposite effect: the addition of H+ into inclusions that are held in melts that are enriched in H2O with respect to the trapped melts. The compositional variability in a suite of 211 olivine-hosted inclusions from the Laki and Skuggafjöll eruptions in Iceland's Eastern Volcanic Zone indicates that diffusive H+ gain governs the H2O content of incompatible trace element depleted inclusions. Individual eruptive units contain olivine-hosted inclusions with widely varying incompatible element concentrations but near-constant H2O. Furthermore, over 40% of the inclusions have H2 O /Ce > 380, significantly higher than the H2O/Ce expected in primary Icelandic melts or mid-ocean ridge basalts (150-280). The fact that the highest H2O/Ce ratios are found in the most incompatible element depleted inclusions indicates that hydration is a consequence of the concurrent mixing and crystallisation of compositionally diverse primary melts. Hydration occurs when olivines containing depleted inclusions with low H2O contents are juxtaposed against more hydrous melts during mixing. Melt inclusions from a single eruption may preserve evidence of both diffusive H+ loss and H+ gain. Trace element data are therefore vital for determining H2O contents of melt inclusions at the time of inclusion trapping and, ultimately, the H2O content of the mantle source regions.

  15. Geoengineering potential of artificially enhanced silicate weathering of olivine.

    PubMed

    Köhler, Peter; Hartmann, Jens; Wolf-Gladrow, Dieter A

    2010-11-23

    Geoengineering is a proposed action to manipulate Earth's climate in order to counteract global warming from anthropogenic greenhouse gas emissions. We investigate the potential of a specific geoengineering technique, carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification, because it influences the global climate via the carbon cycle. If important details of the marine chemistry are taken into consideration, a new mass ratio of CO(2) sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per year directly, if olivine is distributed as fine powder over land areas of the humid tropics, but this rate is limited by the saturation concentration of silicic acid. In our calculations for the Amazon and Congo river catchments, a maximum annual dissolution of 1.8 and 0.4 Pg of olivine seems possible, corresponding to the sequestration of 0.5 and 0.1 Pg of C per year, but these upper limit sequestration rates come at the environmental cost of pH values in the rivers rising to 8.2. Open water dissolution of fine-grained olivine and an enhancement of the biological pump by the rising riverine input of silicic acid might increase our estimate of the carbon sequestration, but additional research is needed here. We finally calculate with a carbon cycle model the consequences of sequestration rates of 1-5 Pg of C per year for the 21st century by this technique. PMID:21059941

  16. Olivine as a key to unlocking Kilauea's magmatic history

    NASA Astrophysics Data System (ADS)

    Garcia, M. O.; Norman, M. D.

    2011-12-01

    Olivine is a ubiquitous mineral in Hawaiian basalts. It is on the liquidus at pressures <0.5 GPa and has the potential to record numerous petrologic processes including the histories of parental magma composition changes, crystal fractionation, magma mixing and crustal contamination. These processes are recorded in olivine composition (major and trace elements, and isotopes) and by melt inclusions trapped within olivine. Here we focus on Kilauea's historical lavas (1820-present) to evaluate the magmatic history one of world's most active volcanoes. Kilauea has shown dramatic variations in it eruptive rate and style (from vigorous, quiescent effusion in 1820 to infrequent explosive activity in 1924 and then to its highest effusion during the last decade). Eruption rates correlate with whole-rock compositional and isotopic variations (P-G 1999). Most Kilauea lavas have normally zoned olivine in equilibrium with whole-rock compositions which belies complex magma chamber processes. Parental magma composition changed rapidly based on the heterogeneity of melt inclusion compositions in higher Mg olivine (>86 forsterite). Melt inclusions from single eruptions show wider variation in ratios of Ca/Al and Nb/Y than observed in lavas for the historical period. Thus, the mantle source is heterogeneous on a small scale and small batches of compositionally distinct melt are frequently delivered to the volcano. These magma batches undergo mixing, fractionation and after caldera collapses (e.g.1924), crustal contamination in the summit reservoir. This work demonstrates that an Ernstonian approach, using minerals to understand petrologic processes, is key to unlocking Kilauea's magmatic processes. Pietruszka, A.P. and Garcia, M.O., 1999, J. Petrol. 40, 1321-1342.

  17. Characterization by EBSD of dislocations and disclinations in olivine: implications for the rheology of olivine-rich aggregates

    NASA Astrophysics Data System (ADS)

    Cordier, P.; Demouchy, S. A.; Beausir, B.; Taupin, V.; Fressengeas, C.

    2013-12-01

    The rheology of olivine-rich rocks remains poorly understood. Only intracrystalline deformation mechanisms involving dislocations are quite well known. In orthorhombic olivine only two slip directions, [100] and [001] can be activated. Most characterizations performed so far involve transmission electron microscopy studies at high magnifications or, at a larger scale, optical or scanning electron microscopy on decorated samples. In the latter case, no detailed characterization of the defects could be done. Orientation maps obtained from high-resolution electron backscattered diffraction allow recovering components of the lattice curvature tensor which in turn allow determination of components of the dislocation density tensor. The geometrically necessary dislocation content can thus be imaged. Recently Beausir & Fressengeas (2013) have shown that with this technique, components of the disclination density tensor could also be determined. Several examples have been provided in metallic alloys. In this study we show that olivine aggregates (both experimentally and naturally deformed) contain pervasive evidence of disclinations dipoles at grain boundaries. The implications on the plastic behavior of olivine rocks are discussed based on a numerical model of the response to an applied shear stress of a grain boundary made of disclinations. Beausir, B. & Fressengeas, C., Disclination densities from EBSD orientation mapping. International Journal of Solids and Structures 50 (1), 137-146 (2013).

  18. Olivine vitrophyres - A nonpristine high-Mg component in lunar breccia 14321

    NASA Technical Reports Server (NTRS)

    Shervais, John W.; Taylor, Lawrence A.; Lindstrom, Marilyn M.

    1988-01-01

    The presence of olivine vitrophyres in breccia 14321 is discussed, suggesting that olivine vitrophyres could account for the high-Mg component of soils and breccias in the lunar highlands. The olivine vitrophyre clasts from 14321 have high bulk MgO and the Mg/(Mg+Fe) ratio is 78 percent. The olivine vitrophyres are impact melt rocks and are rich in KREEP. The high MgO concentration is manifest by skeletal quench crystals of olivine that constitute about 30 percent of the mode.

  19. Olivine and Carbonate Globules in ALH84001: A Terrestrial Analog, and Implications for Water on Mars

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2005-01-01

    Carbonate globules in ALH84001 are associated with small olivine grains an unexpected finding because the olivines equilibrated at high T while the carbonate is chemically zoned and unequilibrated. A possible explanation comes from a terrestrial analog on Spitsbergen (Norway), where some carbonate globules grew in cavities left by aqueous dissolution of olivine. For ALH84001, the same process may have acted, with larger olivines dissolved out and smaller ones shielded inside orthopyroxene. Carbonate would have been deposited in holes where the olivine had been. Later shocks crushed remaining void space, and mobilized feldspathic glass around the carbonates.

  20. Chemical variation and zoning of olivine in lunar dunite 72415 - Near-surface accumulation

    NASA Technical Reports Server (NTRS)

    Ryder, Graham

    1992-01-01

    Electron microprobe remeasurements have been used to reevaluate the range of olivine compositions, including CaO, in lunar dunite sample 72415 and compare that range with olivines in established plutonic rocks. Olivines from ferroan anorthosite 62237 and samples from the Stillwater intrusion were analyzed; literature data for other lunar and terrestrial plutonic samples were used for comparisons. The analyses show that the lunar dunite 72415 contains a range of olivine compositions, that the olivines are zoned, and that they have CaO abundances that are consistent with shallow hypabyssal rather than deep plutonic accumulation.

  1. Evidences and consequences of slow hydrogen diffusion in olivine

    NASA Astrophysics Data System (ADS)

    Padron-Navarta, J. A.; Hermann, J.; O'Neill, H. S.

    2014-12-01

    In the most abundant upper mantle phase, olivine, the presence of hydrogen significantly modifies the timescale of chemical diffusion, plastic deformation, electrical conductivity and the attenuation of seismic waves. Early experiments showed that hydrogen is the fastest species able to diffuse through the olivine lattice. We have found, however, experimental and natural evidence suggesting that hydrogen diffusion can also be orders of magnitude slower. In olivine there are four different hydrogen substitution mechanisms, associated with Mg vacancies, Si vacancies, trivalent cations and titanium substitution, hereafter referred to as H[Mg], H[Si], H[triv] and H[Ti] respectively. We experimentally investigated the dehydroxylation of synthetic forsterite with two contrasting hydrous defect populations: (1) dominated by H[Si], and H[Ti] with subsidiary H[Mg] and H[triv]; and (2) H[Si] exclusively. The loss rates of H[Mg] and H[triv] are in agreement with previous measurements of bulk hydrogen diffusion in forsterite, but the decrease in H[Ti] and H[Si] are ~1.5 and ~ 3 orders of magnitude slower, respectively. The activation energy and pre-exponential terms derived in these experiments are in agreement with the empirical correlation recently proposed based on the Meyer-Nedel compensation law (Jones 2014, G3, 15, 2616-2631). Natural observations attest further to slow hydrogen diffusivity in olivine dominated by H[Ti] and H[Si]. Metamorphic olivines formed after dehydration reactions in the Alpine orogeny preserve their original water contents despite long times of exhumation (2-3 Ma). Closure temperature calculations suggest that using previous fast diffusion rates, these olivines should reequilibrate down to 400°C. Only slow hydrogen diffusion coefficients such as those corresponding to H[Si] are able to explain the observed preservation of water content at the peak metamorphic temperature (700-800°C). These findings have implications for estimating the ascent rate of xenoliths, which are more consistent with other independent constrains, as recently noted (Hilchie et al. 2014, Lithos, 202-203, 429-441). They are also required to assess the time necessary to equilibrate experimental charges, since for the different hydrous defects this time would vary by orders of magnitudes.

  2. Real Time Pore Structure Evolution during Olivine Mineral Carbonation

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Fusseis, F.; Lisabeth, H. P.; Xiao, X.

    2014-12-01

    Aqueous carbonation of ultramafic rocks has been proposed as a promising method for long-term, secure sequestration of carbon dioxide. While chemical kinetics data indicate that carbonation reaction in olivine is one of the fastest among the mg-bearing minerals, in practice, the factors that limit the extent and rate of carbonation in ultramafic rocks are fluid supply and flux. On the one hand, reaction products could produce passivating layer that prohibits further reactions. On the other hand, the increases in solid volume during carbonation could lead to cracking and create new fluid paths. Whether carbonation in ultramafic rocks is self-limiting or self-sustaining has been hotly debated. Experimental evidence of precipitation of reaction products during olivine carbonation was reported. To date, reaction-driven cracking has not been observed. In this paper, we present the first real-time pore structure evolution data using the x-ray synchrotron microtomography. Sodium bicarbonate (NaHCO3) solution was injected into porous olivine aggregates and in-situ pore structure change during olivine carbonation at a constant confining pressure (12 MPa) and a temperature of 200oC was captured at 30 min. interval for ~160 hours. Shortly after the experiment started, filling-in of the existing pores by precipitation of reaction products was visible. The size of the in-fills kept increasing as reactions continued. After ~48 hours, cracking around the in-fill materials became visible. After ~60 hours, these cracks started to show a clear polygonal pattern, similar to the crack patterns usually seen on the surface of drying mud. After ~72 hours, some of the cracks coalesced into large fractures that cut-through the olivine aggregates. New fractures continued to develop and at the end of the experiment, the sample was completely disintegrated by these fractures. We also conducted nanotomography experiments on a sub-volume of the reacted olivine aggregate. Orthogonal sets of incipient cracks were observed, providing clear evidence that these cracks are generated by isotropic tensile stresses. This strongly indicates that the observed cracking was caused by volume expansion during mineral carbonation. The experimental results provide a mechanism for near 100% alteration of ultramafic rocks observed in nature.

  3. O storage capacity of olivine at 8 GPa

    NASA Astrophysics Data System (ADS)

    Withers, Anthony C.; Hirschmann, Marc M.

    2008-04-01

    Olivine crystals were grown in the presence of a hydrous silicate fluid during multi-anvil experiments at 8 GPa and 1,000 1,600°C. Experiments were conducted both in a simple system (FeO MgO SiO2 H2O) and in a more complex system containing additional elements (CaO Na2O Al2O3 Cr2O3 TiO2 FeO MgO SiO2 H2O). Silica activity was buffered by the presence of either pyroxene (high a SiO2) or ferropericlase (low a SiO2), and f_{{text{O}}_{text{2}} } was buffered by the presence of Ni + NiO or Fe + FeO, or constrained by the presence of Fe2O3. Raman spectroscopy was used to identify pyroxene polymorphs in the run products. Clinoenstatite was present in the 1,000°C experiment, and enstatite in experiments at 1,400 1,520°C. The H2O content of olivine was measured using secondary ion mass spectroscopy, and infrared spectroscopy was used to investigate the nature of hydrous defects. The H2O storage capacity of olivine decreases with increasing temperature at 8 GPa. In contrast to previous experimental results at ?2 GPa, no significant effect of varying oxygen fugacity is evident, but H2O storage capacity is enhanced under conditions of low silica activity. No significant growth of low wavenumber (<3,400 cm-1) peaks, generally associated with high f_{{text{O}}_{text{2}} } at low pressure, was observed in the FTIR spectra of olivine from the high f_{{text{O}}_{text{2}} } experiments. Our experiments show that previous high pressure H2O storage capacity measurements for olivine synthesized under more oxidizing conditions than the Earth’s mantle are not likely to be compromised by the f_{{text{O}}_{text{2}} } of the experiments. However, the considerable effect of temperature on H2O storage capacity in olivine must be taken into account to avoid overestimation of the bulk upper mantle H2O storage capacity.

  4. Experimental Replication of Relict "Dusty" Olivine in Type 1B Chondrules

    NASA Technical Reports Server (NTRS)

    Lofgren, Gary E.; Le, L.

    2002-01-01

    Introduction: Relict "dusty" olivine is considered to be a remnants of previous chondrule forming events based on petrographic and chemical evidence. Dynamic crystallization experiments confirm that dusty olivine can be produced by reduction of FeO-rich olivine in Unequilibrated Ordinary Chondrite (UOC) material. The results of these experiments compliment those of who also produced dusty olivine, but from synthetic starting materials. Techniques: Dynamic crystallization experiments were conducted in which UOC material was reduced in presence of graphite. Starting material was coarsely ground GR095554 or WSG95300 that contained olivine of Fo 65-98. Approximately 75 mg. of UOC material was placed in a graphite crucible and sealed in an evacuated silica tube. The tube was suspended in a gas-mixing furnace operated at 1 log unit below the IW buffer. The experiments were as brief as 1.5 hrs up to 121 hrs. Results: Dusty olivine was produced readily in experiments melted at 1400 C for I hr. and cooled between 5 and 100 C/hr or melted at 1300-1400 C for 24 hours. Fe-rich olivine (dusty olivine precursors) that have been partially reduced were common in the experiments melted at 1400 C and cooled at 1000 C/hr or melted at 1200 C for 24 hrs. Relict olivine is absent in experiments melted at 1400 for 24 hrs, melted above 1400 C, or cooled more slowly than 10 C/hr. Relict olivine in the experiments has minimum Fo value of 83 . Thus even in the shortest experiments the most Fe-rich olivine has been altered significantly. The precursor olivine disappears in a few to many hours depending on temperature. The experiments show Fe-rich olivine in all stages of transition to the new dusty form. The olivine is reduced to form dusty olivine in a matter of a few hours at temperatures less than 1400 C and in minutes at higher temperatures. The reduction appears to proceed from the rim of the crystal inward with time. The reduction appears initially rectilinear as if controlled by crystallography, but with time Fe-metal blebs are randomly distributed throughout the olivine. In a given experiment, dusty olivine can be found in varying stages of development, but in the longest experiments, the Fe-metal blebs are dominant and they appear to be migrating out of the olivine. The composition of the dusty olivine ranges from Fo 94-99. The Cr, Mn, and Ca content of the newly formed, dusty olivine is slightly less on average that the precursor olivine, but is till with the range of type 1 olivine. Chadacrysts in the low Ca pyroxene are most common in the higher temperature, more slowly cooled experiments and range in composition from Fo 90-99. Application to chondrule formation: These experiments place time-temperature limits on the preservation of Fe-rich olivine and the production of dusty olivine during chondrule forming events. The reduction process proceeds in a few hours at temperatures above 1400 C and in 10's of hours at temperature between 1200 and 1300 C. This result further confirms th at chondrules form in a few hours to days as suggested earlier. The experiments also confirm that dusty olivine can form from typical Fe-rich olivine in UOC material during the recycling of such olivine in the chondrule forming process.

  5. Infrared spectra of olivine polymorphs: ?, ? phase and spinel

    NASA Astrophysics Data System (ADS)

    Jeanloz, Raymond

    1980-04-01

    Infrared (IR) absorption spectra are presented for olivine (?) and spinel (?) phases of A2SiO4 (A=Fe, Ni, Co) and Mg2GeO4. IR spectra of ? phase (“modified spinel”) Co2SiO4 and of ? Mg2SiO4 are also included. These results provide reference spectra for the identification of olivine high-pressure polymorphs. Isostructural and isochemical correlations are used to support a general interpretation of the spectra and to predict the spectrum of ? Mg2SiO4. A ? Mg2GeO4 sample equilibrated at 1,000° C shows evidence of partial inversion, but one equilibrated at 730° C does not. This suggests that partial inversion could occur in silicate spinels at elevated temperatures and pressures, however no evidence of inversion is seen in the ir spectra of the silicates in this study.

  6. Grinding methods to enhance the reactivity of olivine

    SciTech Connect

    Summers, Cathy A.; Dahlin, David C.; Rush, Gilbert E.; O'Connor, William K.; Gerdemann, Stephen J.

    2005-08-01

    The Albany Research Center (ARC) conducted studies of mechanical activation by conventional and ultrafine grinding techniques to enhance olivine reactivity in mineral carbonation reactions. Activated olivine is one of several solid feed materials used at ARC in reactions with carbon dioxide to form carbonate minerals. This paper compares grinding techniques via energy demand data and product characteristics, including particle size distributions, surface areas, full-width-at-half-maximum (FWHM) XRD analyses, and particle morphology by SEM analyses. Reactivity was calculated by percent conversion to carbonate in subsequent carbonation tests. Particle size reduction has the greatest impact on reactivity, and wet grinding is more energy efficient than dry grinding. Large additional inputs of energy to increase surface area or reduce crystallinity do not result in proportional improvements in reactivity.

  7. Helium diffusion in olivine based on first principles calculations

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Brodholt, John; Lu, Xiancai

    2015-05-01

    As a key trace element involved in mantle evolution, the transport properties of helium in the mantle are important for understanding the thermal and chemical evolution of the Earth. However, the mobility of helium in the mantle is still unclear due to the scarcity of measured diffusion data from minerals under mantle conditions. In this study, we used first principles calculations based on density functional theory to calculate the absolute diffusion coefficients of the helium in olivine. Using the climbing images nudged elastic band method, we defined the diffusion pathways, the activation energies (Ea), and the prefactors. Our results demonstrate that the diffusion of helium has moderate anisotropy. The directionally dependent diffusion of helium in olivine can be written in Arrhenius form as follows.

  8. Space Weathering Evolution on Airless Bodies - Laboratory Simulations with Olivine

    NASA Astrophysics Data System (ADS)

    Kohout, Tomas; Cuda, J.; Bradley, T.; Britt, D.; Filip, J.; Tucek, J.; Malina, O.; Kaslik, J.; Siskova, K.; Kletetschka, G.; Zboril, R.

    2013-10-01

    Lunar-type space weathering of airless bodies is associated with nanophase iron (npFe0) production in Fe bearing silicate minerals that is often responsible for observable changes of its reflectance spectra. A new method of controlled npFe0 production on olivine grains was developed in order to quantitatively evaluate spectral changes related to space weathering and presence of npFe0. Through a two-step thermal treatment a series of olivine samples with increasing concentration of iron nanoparticles on the grain surfaces was prepared. The grain size of the npFe0 particles was kept in the same range 5-20 nm). Magnetic methods were used to estimate npFe0 concentration. Compared to fresh olivine, treated samples exhibit the spectral characteristics of lunar type space weathering (darkening, shallowing of 1 µm olivine absorption band, and reddening) related to increasing presence of npFe0. From quantitative point of view, a logarithmic trend was found between spectral changes and npFe0 concentration. One sample with additional population of larger ~50 nm npFe0 particles follows the darkening and the 1 µm band shallowing trend, but does not fully follow the reddening trend. This is due to fact that the larger 40 50 nm sized) npFe0 particles do not contribute to the spectral slope change. The observed logarithmic trend between the spectral changes and the npFe0 concentration give constrains on time evolution of space weathering. In the case of constant micro impact, solar wind and cosmic radiation on a regolith, the npFe0 concentration increases linearly with time while spectral changes related to space weathering evolve logarithmically with time.

  9. Experimental study of Mg isotope fractionation during olivine dissolution

    NASA Astrophysics Data System (ADS)

    Qiu, L.; Wang, Z.

    2012-12-01

    The dissolution of silicate minerals plays important roles in modifying the chemical composition of the ocean and earth crust. Previous studies show secondary clay minerals produced as a by-product of dissolution are enriched in heavy Mg isotopes compared with their protolith. In this study, batch olivine dissolution experiments were conducted in an autoclave to understand the evolution of Mg isotope composition in the solution as a function of controlled experimental conditions, including initial pH of the fluid (10.02 or 2.02), temperature (50, 100, or 200oC), olivine-grain size (<30?m powder or single olivine grain of ~0.2g/each), and duration of the experiments (up to ~60 hours). At the end of experiments, solid minerals were characterized by SEM and EM, and the solution was analyzed for major and trace element, and Mg isotope compositions by Element-XR and Neptune at Yale University. The Mg/Si ratio of the solution and the SEM and EM characterization of the solid phases indicate the formation of secondary mineral-talc in experiments with alkaline solutions, is consistent with the calculated saturation index. Significant Mg isotope fractionations were also observed in these experiments, which decrease with increasing temperature (e.g., up to ~ -5.8‰ at 50oC vs. -0.72 ‰ at 200oC), but increase with increasing the duration of the experiments. In contrast, little fractionation was observed in experiments with acidic solutions at low temperatures, or short duration of the experiments at high temperatures. These results indicate that dissolution of olivine (even in our closed system experiments) is a surface controlled process, during which Mg isotopes fractionate insignificantly, whereas secondary minerals formed during the process are strongly enriched in heavy Mg isotopes, leaving the solutions depleted in 26Mg. The fractionation factors between solution and talc have been estimated for these experiments as well.

  10. Chemical frost weathering of olivine: Experimental study and implications

    NASA Technical Reports Server (NTRS)

    Harris, S. L.; Huguenin, R. L.

    1987-01-01

    New experimental results are reported on the frost weathering of olivine. After first weathering, a decrease in Fe sup 2(+)M(2) absorption bands were noted. This decrease is related to the protonation of O(+) in the mineral. It is contented that this reaction may result in the regolith storage of 100 to 1000 m of H(sub 2) over the history of Mars.

  11. Olivine-rich asteroids in the main asteroid belt

    NASA Astrophysics Data System (ADS)

    DeMeo, Francesca E.; Polishook, David; Carry, Benoit; Moskovitz, Nick; Burt, Brian; Binzel, Rick

    2015-11-01

    Olivine-dominated asteroids, classified as A-types with near-infrared spectral measurements are largely thought to be the mantle remnants of disrupted differentiated small bodies. These A-type asteroids hold clues to asteroid differentiation and to the collisional history of those differentiated bodies. Preliminary studies of the abundance and distribution of A-type asteroids were performed by Carvano et al. (2010) and DeMeo & Carry (2013, 2014) using the Sloan Digital Sky Survey (SDSS). To confidently identify these olivine-dominated A-type asteroids, however, near-infrared spectral measurements are needed to identify the distinct broad and deep 1-micron olivine absorption feature. Using the Sloan Digital Sky Survey Moving Object Catalog to select A-type asteroid candidates, we have performed a near-infrared spectral survey of over 70 asteroids with SpeX on the IRTF. We present the abundance and distribution of A-type asteroids throughout the main asteroid belt and compare these results with similar surveys for basalt-rich V-type asteroids (e.g. Moskovitz et al. 2008). This work is supported by NASA under grant number NNX12AL26G issued through the Planetary Astronomy Program.

  12. The Olivine to Spinel Transformation Unmasked: A Direct Atomic View

    NASA Astrophysics Data System (ADS)

    Drennan, J.; Liu, Z.; Kelly, P.

    2002-12-01

    High-resolution transmission electron microscopy (HRTEM) of partially transformed samples of Mg2GeO4 have revealed a clear picture of the atomic re-arrangements that take place when the olivine form of the compound transforms to the spinel type under the influence of high pressure and temperatures. This important transformation is an anolog of the olivine-spinel transition in mantle silicates and has been the subject of much speculation. In this study it was found that when Mg2GeO4 was subjected to 6Gpa pressure at 600oC for 10 minutes, samples could be produced that contained both structure types with perfectly preserved interface regions. Examination of the atomic structure images of well-prepared specimens revealed a mechanism of transformation, which combines both, a shear component on the anion sub-lattice followed by the passage of a correcting dislocation which very effectively rearranges the cations. The shearing action transforms the hexagonal close packed array of anions in the olivine structure to a packing sequence that defines the face centred close packed structure of the spinel form. The dislocation associated with each shear has a Burgers' vector perpendicular to the anion shear direction and the passage of these dislocations places the cations in the correct spinel sites. These effects are directly observed in atomic resolution images and uniquely define the process, which may have implications in the continuing search for the cause of "deep earthquakes".

  13. Creep behavior of Fe-bearing olivine under hydrous conditions

    NASA Astrophysics Data System (ADS)

    Tasaka, Miki; Zimmerman, Mark E.; Kohlstedt, David L.

    2015-09-01

    To understand the effect of iron content on the creep behavior of olivine, (MgxFe(1 - x))2SiO4, under hydrous conditions, we have conducted tri-axial compressive creep experiments on samples of polycrystalline olivine with Mg contents of x = 0.53, 0.77, 0.90, and 1. Samples were deformed at stresses of 25 to 320 MPa, temperatures of 1050° to 1200°C, a confining pressure of 300 MPa, and a water fugacity of 300 MPa using a gas-medium high-pressure apparatus. Under hydrous conditions, our results yield the following expression for strain rate as a function of iron content for 0.53 ? x ? 0.90 in the dislocation creep regime: ??=??0.90((1-x/0.1))1/2exp[226×1030.9-x/RT]. In this equation, the strain rate of San Carlos olivine, ??0.90, is a function of T, ?, and fH2O. As previously shown for anhydrous conditions, an increase in iron content directly increases creep rate. In addition, an increase in iron content increases hydrogen solubility and therefore indirectly increases creep rate. This flow law allows us to extrapolate our results to a wide range of mantle conditions, not only for Earth's mantle but also for the mantle of Mars.

  14. The effect of water on the electrical conductivity of olivine.

    PubMed

    Wang, Duojun; Mookherjee, Mainak; Xu, Yousheng; Karato, Shun-ichiro

    2006-10-26

    It is well known that water (as a source of hydrogen) affects the physical and chemical properties of minerals--for example, plastic deformation and melting temperature--and accordingly plays an important role in the dynamics and geochemical evolution of the Earth. Estimating the water content of the Earth's mantle by direct sampling provides only a limited data set from shallow regions (<200 km depth). Geophysical observations such as electrical conductivity are considered to be sensitive to water content, but there has been no experimental study to determine the effect of water on the electrical conductivity of olivine, the most abundant mineral in the Earth's mantle. Here we report a laboratory study of the dependence of the electrical conductivity of olivine aggregates on water content at high temperature and pressure. The electrical conductivity of synthetic polycrystalline olivine was determined from a.c. impedance measurements at a pressure of 4 GPa for a temperature range of 873-1,273 K for water contents of 0.01-0.08 wt%. The results show that the electrical conductivity is strongly dependent on water content but depends only modestly on temperature. The water content dependence of conductivity is best explained by a model in which electrical conduction is due to the motion of free protons. A comparison of the laboratory data with geophysical observations suggests that the typical oceanic asthenosphere contains approximately 10(-2) wt% water, whereas the water content in the continental upper mantle is less than approximately 10(-3) wt%. PMID:17066032

  15. Olivine crystals align during diffusion creep of Earth's upper mantle.

    PubMed

    Miyazaki, Tomonori; Sueyoshi, Kenta; Hiraga, Takehiko

    2013-10-17

    The crystallographic preferred orientation (CPO) of olivine produced during dislocation creep is considered to be the primary cause of elastic anisotropy in Earth's upper mantle and is often used to determine the direction of mantle flow. A fundamental question remains, however, as to whether the alignment of olivine crystals is uniquely produced by dislocation creep. Here we report the development of CPO in iron-free olivine (that is, forsterite) during diffusion creep; the intensity and pattern of CPO depend on temperature and the presence of melt, which control the appearance of crystallographic planes on grain boundaries. Grain boundary sliding on these crystallography-controlled boundaries accommodated by diffusion contributes to grain rotation, resulting in a CPO. We show that strong radial anisotropy is anticipated at temperatures corresponding to depths where melting initiates to depths where strongly anisotropic and low seismic velocities are detected. Conversely, weak anisotropy is anticipated at temperatures corresponding to depths where almost isotropic mantle is found. We propose diffusion creep to be the primary means of mantle flow. PMID:24132289

  16. New measurements of activation volume in olivine under anhydrous conditions

    NASA Astrophysics Data System (ADS)

    Durham, W. B.; Mei, S.; Kohlstedt, D. L.; Wang, L.; Dixon, N. A.

    2009-01-01

    A new cell assembly for the deformation-DIA (D-DIA) shows promise for limiting the water content of samples and providing a more mechanically stable environment for deformation. The 6-mm cubic cell consists of a 6-mm diameter mullite sphere cradled in a web of unfired pyrophyllite. The pyrophyllite flows during initial compression of the D-DIA to form gaskets between the six anvils while the mullite flows to become a nearly cubic-shaped pressure medium. Measurements on olivine indicate more than one order of magnitude drop in water content to <40 ppm H/Si compared with the boron-epoxy medium. Improved mechanical stability is achieved by elimination of the thermocouple from the assembly and determination of temperature from calibration curves of furnace power vs. temperature. Three samples of polycrystalline orthopyroxene-buffer San Carlos olivine have been deformed in high-temperature creep in the new cell, at pressures of 2.7-4.9 GPa and temperatures near 1473 K. Strength is consistent with that measured in the gas-apparatus at lower pressures. Over the pressure range investigated we resolve an activation volume for creep of dry olivine of V* = 9.5 ± 7 × 10 -6 m 3/mol.

  17. From olivine to ringwoodite: a TEM study of a complex process

    NASA Astrophysics Data System (ADS)

    Pittarello, Lidia; Ji, Gang; Yamaguchi, Akira; Schryvers, Dominique; Debaille, Vinciane; Claeys, Philippe

    2015-05-01

    The study of shock metamorphism of olivine might help to constrain impact events in the history of meteorites. Although shock features in olivine are well known, so far, there are processes that are not yet completely understood. In shock veins, olivine clasts with a complex structure, with a ringwoodite rim and a dense network of lamellae of unidentified nature in the core, have been reported in the literature. A highly shocked (S5-6), L6 meteorite, Asuka 09584, which was recently collected in Antarctica by a Belgian-Japanese joint expedition, contains this type of shocked olivine clasts and has been, therefore, selected for detailed investigations of these features by transmission electron microscopy (TEM). Petrographic, geochemical, and crystallographic studies showed that the rim of these shocked clasts consists of an aggregate of nanocrystals of ringwoodite, with lower Mg/Fe ratio than the unshocked olivine. The clast's core consists of an aggregate of iso-oriented grains of olivine and wadsleyite, with higher Mg/Fe ratio than the unshocked olivine. This aggregate is crosscut by veinlets of nanocrystals of olivine, with extremely low Mg/Fe ratio. The formation of the ringwoodite rim is likely due to solid-state, diffusion-controlled, transformation from olivine under high-temperature conditions. The aggregate of iso-oriented olivine and wadsleyite crystals is interpreted to have formed also by a solid-state process, likely by coherent intracrystalline nucleation. Following the compression, shock release is believed to have caused opening of cracks and fractures in olivine and formation of olivine melt, which has lately crystallized under postshock equilibrium pressure conditions as olivine.

  18. A New Spinel-Olivine Oxybarometer: Near-Liquidus Partitioning of V between Olivine-Melt, Spinel-Melt, and Spinel-Olivine in Martian Basalt Composition Y980459 as a Function of Oxygen Fugacity

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Le, L.; Burger, P. V.; Shearer, C. K.; Bell, A. S.; Jones, J.

    2013-01-01

    Our research on valence state partitioning began in 2005 with a review of Cr, Fe, Ti, and V partitioning among crystallographic sites in olivine, pyroxene, and spinel [1]. That paper was followed by several on QUE94201 melt composition and specifically on Cr, V, and Eu partitioning between pyroxene and melt [2-5]. This paper represents the continuation of our examination of the partitioning of multivalent V between olivine, spinel, and melt in martian olivine-phyric basalts of Y980459 composition [6, 7]. Here we introduce a new, potentially powerful oxybarometer, V partitioning between spinel and olivine, which can be used when no melt is preserved in the meteorite. The bulk composition of QUE94201 was ideal for our study of martian pyroxene-phyric basalts and specifically the partitioning between pyroxene-melt for Cr, V, and Eu. Likewise, bulk composition Y980459 is ideal for the study of martian olivine-phyric basalts and specifically for olivine-melt, spinel-melt, and spinel-olivine partitioning of V as a function of oxygen fugacity.

  19. Fe/Mn in olivine of carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Steele, Ian M.

    1993-01-01

    Olivines in primitive meteorites show a range of Fe/Mn both within one grain and among grains suggesting that they have recorded changing conditions during or after growth. Because olivine should be an early forming phase, Fe/Mn is used here to infer these earliest conditions. Initial Fe/Mn in cores of isolated, euhedral forsterite in both C2 and C3 meteorites ranges from 25 to 35 but differs at grain edge. Murchison (C2) forsterites show Fe/Mn approaching 1.0 at the grain edge while Ornans Fe/Mn is near 60 at grain edge. These values are lower than the matrix Fe/Mn for both meteorites and the distinct difference in zoning profile indicates different processes operating during and after grain growth. The Fe/Mn of bulk samples from a particular source such as the Moon is nearly constant. Individual samples show variation suggesting that there is some fractionation of Mn from Fe. Minerals have their individual ranges of Fe/Mn which has been used to recognize different types of olivine within one meteorite. Extreme values of Fe/Mn below 1.0 occur in forsterite from some IDP's, UOC matrix, and C1 meteorites. There are apparently no detailed studies of Fe/Mn variation within single olivine grains. Forsterite grains in C2 and C3 carbonaceous chondrites show complex zoning, and the nearly pure forsterites (Fo greater than approximately 99.5) have high levels of some minor elements including Ti, Al, V, and Sc. There is disagreement on the original source of these grains and both chondrule and vapor growth have been proposed. In addition, there is clear evidence that diffusion has affected the outer margins but in some cases the whole grain. Within the cores, the FeO range is limited, and if growing under constant conditions, the Fe/Mn should be near constant as there is little fractionation of Mn from Fe by forsterite. Additionally, there are apparently no co-crystallizing phases as evidenced by a lack of common inclusions in the forsterites. These observations are now followed by analyses of isolated olivine grains in C2 and C3 meteorites.

  20. Enhanced olivine carbonation within a basalt as compared to single-phase experiments: the impact of redox and bulk composition on the dissolution kinetics of olivine

    NASA Astrophysics Data System (ADS)

    Sissmann, O.; Brunet, F.; Martinez, I.; Guyot, F. J.; Verlaguet, A.; Pinquier, Y.; Garcia, B.; Chardin, M.; Kohler, E.; Daval, D.

    2014-12-01

    Olivine (Mg,Fe)2SiO4, which is one of the major mineral constituents of mafic and ultramafic rocks, has an attractive potential for CO2 mineral sequestration, as it possesses a high content of carbonate-forming divalent cations and exhibits one of the highest dissolution rate amongst rock-forming minerals. This study reports drastic differences in carbonation yields between experiments performed on olivine-rich basalt samples and on olivine separates (a more restricted chemical system). Batch experiments were conducted in water at 150°C and pCO2 = 280 bars on a Mg-rich tholeiitic basalt (9.3 wt.% MgO and 12.2 wt.% CaO), composed of olivine, Ti-magnetite, plagioclase and clinopyroxene. After 45 days of reaction, 56 wt.% of the initial MgO has reacted with CO2 to form Fe-bearing magnesite (Mg0.8Fe0.2)CO3 along with minor calcium carbonates. The substantial decrease of olivine content upon carbonation supports the idea that ferroan magnesite formation mainly follows from olivine dissolution. In contrast, in experiments performed under similar run durations and P/T conditions with a San Carlos olivine separate (47.8 wt.% MgO) of similar grain size, only 5 wt.% of the initial MgO content reacted to form Fe-bearing magnesite. The overall carbonation kinetics of the basalt is enhanced by a factor of 40. It could be accounted for by differences in chemical and textural properties of the secondary-silica layer which covers reacted olivine grains in both types of sample. A TEM inspection of mineral surfaces shows that the thin amorphous silica layer (~100 nm) is porous in the case of the basalt sample and that it contains significant amounts of iron and aluminum. Thus, we propose that the composition of the olivine environment itself can strongly influence the olivine dissolution-carbonation process. Consequently, laboratory data obtained on olivine separates might yield a conservative estimate of the true carbonation potential of olivine-bearing basaltic rocks. More generally, this study questions the approach which consists in evaluating the carbonation potential of a rock based on experiments on separate minerals. It also emphasizes the impact of fO2 and potential co-injected gases on the olivine dissolution-carbonation process.

  1. LIME silicates in amoeboid olivine aggregates in carbonaceous chondrites: Indicator of nebular and asteroidal processes

    NASA Astrophysics Data System (ADS)

    Komatsu, Mutsumi; Fagan, Timothy J.; Mikouchi, Takashi; Petaev, Michail I.; Zolensky, Michael E.

    2015-07-01

    MnO/FeO ratios in olivine from amoeboid olivine aggregates (AOAs) reflect conditions of nebular condensation and can be used in concert with matrix textures to compare metamorphic conditions in carbonaceous chondrites. LIME (low-iron, Mn-enriched) olivine was identified in AOAs from Y-81020 (CO3.05), Kaba (CV~3.1), and in Y-86009 (CV3), Y-86751 (CV3), NWA 1152 (CR/CV3), but was not identified in AOAs from Efremovka (CV3.1-3.4) or Allende (CV>3.6). According to thermodynamic models of nebular condensation, LIME olivine is stable at lower temperatures than Mn-poor olivine and at low oxygen fugacities (dust enrichment <10× solar). Although this set of samples does not represent a single metamorphic sequence, the higher subtypes tend to have AOA olivine with lower Mn/Fe, suggesting that Mn/Fe decreases during parent body metamorphism. Y-81020 has the lowest subtype and most forsteritic AOA olivine (Fo>95) in our study, whereas Efremovka AOAs are slightly Fe-rich (Fo>92). AOA olivines from Kaba are mostly forsteritic, but rare Fe-rich olivine precipitated from an aqueous fluid. A combination of precipitation of Fe-rich olivine and diffusion of Fe into primary olivine grains resulted in iron-rich compositions (Fo97-59) in Allende AOAs. Variations from fine-grained, nonporous matrix toward higher porosity and coarser lath-like matrix olivine can be divided into six stages represented by (1) Y-81020, Efremovka, NWA 1152; (2) Y-86751 lithology B; (3) Y-86009; (4) Kaba; (5) Y-86751 lithology A; (6) Allende. These stages are inferred to represent general degree of metamorphism, although the specific roles of thermally driven grain growth and diffusion versus aqueous dissolution and precipitation remain uncertain.

  2. [Study on the FTIR spectra of OH in olivines from mengyin kimberlite].

    PubMed

    Ai, Qun; Yang, Zhi-jun; Zeng, Xiang-qing; Zheng, Yun-long; Hu, Piao-ye

    2013-09-01

    The results of FTIR spectra study of OH in olivines from Mengyin kimberlite show that there are more than 60 OH absorption peaks in the range of 3800-3000 cm(-1). We identified four major spectral features in the OH absorption bands of kimberlitic olivines. One is with nuOH in the range of 3800-3700 cm(-1), which is caused by the vapour of the room circumstance, and can not be regarded as intrinsic or non-intrinsic nuOH of the olivines. Another one is with nuOH in the range of 3710-3620 cm(-1), which belongs to three "water"-bearing minerals including serpentine, talc and Mg-bearing amphiboles, which is the non-intrinsic nuOH of the olivines. There is the possibility that H in hydrous minerals mainly entered into olivines during post-emplacement processes of the kimberlite magma. The third one is with nuOH in the range of 3620-3425 cm(-1), which originated from H occupying the Si-defect in the olivine structure, forming humite-like defects, and/or the defects that H occupies (Mg,Fe)-depletion, which is certainly attributed to the intrinsic nuOH of the olivines. In this case, H possibly entered into olivines following its immersion in the high temperature and rich fluid kimberlite magma in the mantle circumstance. The last one is with nuOH in the range of 3425-3000 cm(-1). In this area, nuOH is assigned to fluid inclusions of the olivines, and is the non-intrinsic nuOH of olivines. Fluid inclusions can enter into the olivines either during post-emplacement processes of the kimberlite magma or during the periods that olivines were formed in the mantle. PMID:24369634

  3. Mid-Infrared Reflectance Spectra of Pulsed Laser Irradiated Olivine Grains

    NASA Astrophysics Data System (ADS)

    Yang, Y. Z.; Yuan, Y.; Wang, Z. W.; Zhang, H.; Jin, W. D.; Hsu, W. B.

    2015-11-01

    To understand the effects of space weathering processes on VNIR and MIR reflectance spectra, we carried out pulsed laser irradiation simulations and reflectance spectroscopic measurements of olivine grains.

  4. Magmatic history and parental melt composition of olivine-phyric shergottite LAR 06319: Importance of magmatic degassing and olivine antecrysts in Martian magmatism

    NASA Astrophysics Data System (ADS)

    Balta, J. Brian; Sanborn, Matthew; McSween, Harry Y.; Wadhwa, Meenakshi

    2013-08-01

    Several olivine-phyric shergottites contain enough olivine that they could conceivably represent the products of closed-system crystallization of primary melts derived from partial melting of the Martian mantle. Larkman Nunatak (LAR) 06319 has been suggested to represent a close approach to a Martian primary liquid composition based on approximate equilibrium between its olivine and groundmass. To better understand the olivine-melt relationship and the evolution of this meteorite, we report the results of new petrographic and chemical analyses. We find that olivine megacryst cores are generally not in equilibrium with the groundmass, but rather have been homogenized by diffusion to Mg# 72. We have identified two unique grain types: an olivine glomerocryst and an olivine grain preserving a primary magmatic boundary that constrains the time scale of eruption to be on the order of hours. We also report the presence of trace oxide phases and phosphate compositions that suggest that the melt contained approximately 1.1% H2O and lost volatiles during cooling, also associated with an increase in oxygen fugacity upon degassing. We additionally report in situ rare earth element measurements of the various mineral phases in LAR 06319. Based on these reported trace element abundances, we estimate the oxygen fugacity in the LAR 06319 parent melt early in its crystallization sequence (i.e., at the time of crystallization of the low-Ca and high-Ca pyroxenes), the rare earth element composition of the parent melt, and those of melts in equilibrium with later formed phases. We suggest that LAR 06319 represents the product of closed-system crystallization within a shallow magma chamber, with additional olivine accumulated from a cumulate pile. We infer that the olivine megacrysts are antecrysts, derived from a single magma chamber, but not directly related to the host magma, and suggest that mixing of antecrysts within magma chambers may be a common process in Martian magmatic systems.

  5. Deformation of olivine single crystals under lithospheric conditions

    NASA Astrophysics Data System (ADS)

    Demouchy, S.; Tommasi, A.; Cordier, P.

    2012-12-01

    The rheology of mantle rocks at lithospheric temperatures (<1000°C) remains poorly constrained, in contrast to the extensive experimental data on creep of olivine single crystals and polycrystalline aggregates at high temperature (T > 1200°C). Consequently, we have performed tri-axial compression experiments on oriented single crystals and polycrystalline aggregates of San Carlos olivine at temperatures ranging from 800° to 1090°C. The experiments were carried out at a confining pressure of 300 MPa in a high-resolution gas-medium mechanical testing apparatus at constant strain rates ranging from 7 × 10-6 s-1 to 1 × 10-4 s-1 . Compression was applied along three different crystallographic directions: [101]c, [110]c and [011]c, to activate the several slip systems. Yield differential stresses range from 88 to 1076 MPa. To constrain hardening, stick-and-slip, or strain localization behaviors, all samples were deformed at constant displacement rate for finite strains between 4 to 23 %. Hardening was observed in all experiments and the maximum differential stress often overcame the confining pressure. EBSD mapping highlights macroscale bending of the crystalline network in three crystals. TEM observations on several samples show dislocations with [100] and [001] Burgers vectors in all samples, but dislocation arrangements vary. The results from the present study permit to refining the power-law expressing the strain rate dependence on stress and temperature for olivine, allowing its application to the lithospheric mantle. Our experiments confirm that previous published high-temperature power flow laws overestimate the strength of lithospheric mantle and that the transition to low-temperature creep occurs at higher temperatures than it has previously been established.

  6. Chromium valences in ureilite olivine and implications for ureilite petrogenesis

    NASA Astrophysics Data System (ADS)

    Goodrich, C. A.; Sutton, S. R.; Wirick, S.; Jercinovic, M. J.

    2013-12-01

    Ureilites are a group of ultramafic achondrites commonly thought to be residues of partial melting on a carbon-rich asteroid. They show a large variation in FeO content (olivine Fo values ranging from ?74 to 95) that cannot be due to igneous fractionation and suggests instead variation in oxidation state. The presence of chromite in only a few of the most ferroan (Fo 75-76) samples appears to support such a model. MicroXANES analyses were used in this study to determine the valence states of Cr (previously unknown) in olivine cores of 11 main group ureilites. The goal of this work was to use a method that is independent of Fo to determine the oxidation conditions under which ureilites formed, in order to evaluate whether the ureilite FeO-variation is correlated with oxidation state, and whether it is nebular or planetary in origin. Two of the analyzed samples, LEW 88774 (Fo 74.2) and NWA 766 (Fo 76.7) contain primary chromite; two others, LAP 03587 (Fo 74.4) and CMS 04048 (Fo 76.2) contain sub-micrometer-sized exsolutions of chromite + Ca-rich pyroxene in olivine; and one, EET 96328 (Fo 85.2) contains an unusual chromite grain of uncertain origin. No chromite has been observed in the remaining six samples (Fo 77.4-92.3). Chromium in olivine in all eleven samples was found to be dominated by the divalent species, with valences ranging from 2.10 ± 0.02 (1?) to 2.46 ± 0.04. The non-chromite-bearing ureilites have the most reduced Cr, with a weighted mean valence of 2.12 ± 0.01, i.e., Cr2+/Cr3+ = 7.33. All low-Fo chromite-bearing ureilites have more oxidized Cr, with valences ranging from 2.22 ± 0.03 to 2.46 ± 0.04. EET 96328, whose chromite grain we interpret as a late-crystallizing phase, yielded a reduced Cr valence of 2.15 ± 0.07, similar to the non-chromite-bearing samples. Based on the measured Cr valences, magmatic (1200-1300 °C) oxygen fugacities (fO2) of the non-chromite-bearing samples were estimated to be in the range IW-1.9 to IW-2.8 (assuming basaltic melt composition), consistent with fO2 values obtained by assuming olivine-silica-iron metal (OSI) equilibrium. For the primary chromite-bearing-ureilites, the corresponding fO2 were estimated (again, assuming basaltic melt composition) to be ?IW to IW+1.0, i.e., several orders of magnitude more oxidizing than the conditions estimated for the chromite-free ureilites. In terms of Fo and Cr valence properties, ureilites appear to form two groups rather than a single “Cr-valence (or fO2) vs. Fo” trend. The chromite-bearing ureilites show little variation in Fo (?74-76) but significant variation in Cr valence, while the non-chromite-bearing ureilites show significant variation in Fo (?77-95) and little variation in Cr valence. These groups are unrelated to petrologic type (i.e., olivine-pigeonite, olivine-orthopyroxene, or augite-bearing). The chromite-bearing ureilites also have lower contents of Cr in olivine than most non-chromite-bearing ureilites, consistent with predictions based on Cr olivine/melt partitioning in spinel saturated vs. non-spinel-saturated systems. Under the assumption that at magmatic temperatures graphite-gas equilibria controlled fO2 at all depths on the ureilite parent body, we conclude: (1) that ureilite precursor materials having the Fo and Cr valence properties now observed in ureilites are unlikely to have been preserved during planetary processing; and (2) that the Fo and Cr valence properties now observed in ureilites are consistent with having been established by high-temperature carbon redox control over a range of depths on a plausible-sized ureilite parent body. The apparent limit on ureilite Fo values around 74-76 suggests that the precursor material(s) had bulk mg# ? that of LL chondrites.

  7. Phosphorus as indicator of magmatic olivine residence time, morphology and growth rate

    NASA Astrophysics Data System (ADS)

    Sobolev, Alexander; Batanova, Valentina

    2015-04-01

    Phosphorus is among of slowest elements by diffusion rate in silicate melts and crystals (e.g. Spandler et al, 2007). In the same time it is moderately incompatible to compatible with olivine (Brunet & Chazot, 2001; Grant & Kohn, 2013). This makes phosphorus valuable tracer of olivine crystallization in natural conditions. Indeed, it is shown that natural magmatic olivine crystals commonly posses strong and complicated zoning in phosphorus (Milman-Barris et al, 2008; Welsch et al, 2014). In this paper we intend to review phosphorus behavior in olivine in published experimental and natural olivine studies and present large set of new EPMA data on phosphorus zoning in olivine phenocrysts from MORBs, OIBs, komatiites and kimberlites. We will show that sharp olivine zones enriched in phosphorus by a factor of 10-20 over prediction by equilibrium partition may be due to formation of P-rich boundary layer on the interface of fast growing olivine. This is proved by finding of small-size (normally 10 mkm or less) exceptionally P-rich melt inclusions in olivine, which are otherwise similar in composition to typical melt. These observations could provide potential olivine growth speedometer. We will also demonstrate, that sharp zoning in phosphorus may provide valuable information on the residence time of olivine crystals in different environments: magma chambers and conduits as well as mantle sources. This study has been founded by Russian Science Foundation grant 14-17-00491. References: Spandler, et al, 2007, Nature, v. 447, p. 303-306; Brunet & Chazot, 2001, Chemical Geology, v. 176, p. 51-72; Grant & Kohn, 2013, American Mineralogist, v. 98, p. 1860-1869; Milman-Barris et al, 2008, Contr. Min. Petrol. v. 155, p.739-765; Welsch et al, 2014, Geology, v. 42, p.867-870.

  8. Temperature-dependent Infrared Optical Constants of Olivine and Enstatite

    NASA Astrophysics Data System (ADS)

    Zeidler, S.; Mutschke, H.; Posch, Th.

    2015-01-01

    Since the Infrared Space Observatory (ISO) mission, it has become clear that dust in circumstellar disks and outflows consists partly of crystalline silicates of pyroxene and olivine type. An exact mineralogical analysis of the dust infrared emission spectra relies on laboratory spectra, which, however, have been mostly measured at room temperature so far. Given that infrared spectral features depend on the thermal excitation of the crystal's vibrational modes, laboratory spectra measured at various (low and high) temperatures, corresponding to the thermal conditions at different distances from the star, can improve the accuracy of such analyses considerably. We have measured the complex refractive index in a temperature range of 10-973 K for one mineral of each of those types of silicate, i.e., for an olivine and an enstatite of typical (terrestrial) composition. Thus, our data extend the temperature range of previous data to higher values and the compositional range to higher iron contents. We analyze the temperature dependence of oscillator frequencies and damping parameters governing the spectral characteristics of the bands and calculate absorption cross-sectional spectra that can be compared with astronomical emission spectra. We demonstrate the usefulness of our new data by comparing spectra calculated for a 100 K dust temperature with the ISO SWS spectrum of IRAS 09425-6040.

  9. Systematics of Ni, Co, Cr and V in Olivine from Planetary Melt Systems: Martian Basalts

    NASA Technical Reports Server (NTRS)

    Herd, C. D. K.; Jones, J. H.; Shearer, C. K.; Papike, J. J.

    2001-01-01

    Secondary Ion Mass Spectrometry (SIMS) data for Ni, Co, Cr, and V in olivine in martian basalts is compared to data from lunar and terrestrial basalts. We use experimentally-derived and published D values to calculate as-yet unsampled, olivine-bearing, non-cumulus melt compositions. Additional information is contained in the original extended abstract.

  10. Simultaneous Modeling of Thermopower and Electrical Conduction in Olivine Steven Constable1

    E-print Network

    Key, Kerry

    Simultaneous Modeling of Thermopower and Electrical Conduction in Olivine Steven Constable1 Abstract. Measurements of conductivity and thermopower as a function of oxygen fu- gacity (fO2 ) are used to derive a model for conduction in olivine. Thermopower at 1000­ 1200 C is between 50 and 400 µV/K and has

  11. Hydrous olivine unable to account for conductivity anomaly at the top of the asthenosphere.

    PubMed

    Yoshino, Takashi; Matsuzaki, Takuya; Yamashita, Shigeru; Katsura, Tomoo

    2006-10-26

    The oceanic asthenosphere is observed to have high electrical conductivity, which is highly anisotropic in some locations. In the directions parallel and normal to the plate motion, the conductivity is of the order of 10(-1) and 10(-2) S m(-1), respectively, which cannot be explained by the conductivity of anhydrous olivine. But because hydrogen can be incorporated in olivine at mantle pressures, this observation has been attributed to olivine hydration, which might cause anisotropically high conductivity by proton migration. To examine this hypothesis, here we report the effect of water on electrical conductivity and its anisotropy for hydrogen-doped and undoped olivine at 500-1,500 K and 3 GPa. The hydrous olivine has much higher conductivity and lower activation energy than anhydrous olivine in the investigated temperature range. Nevertheless, extrapolation of the experimental results suggests that conductivity of hydrous olivine at the top of the asthenosphere should be nearly isotropic and only of the order of 10(-2) S m(-1). Our data indicate that the hydration of olivine cannot account for the geophysical observations, which instead may be explained by the presence of partial melt elongated in the direction of plate motion. PMID:17066031

  12. Relict olivine grains, chondrule recycling, and implications for the chemical, thermal, and mechanical processing

    E-print Network

    Floss, Christine

    . Louis, MO 63130, USA Received 7 March 2008; accepted in revised form 20 August 2008; available online 11 elements (Cr, Mn, P, Rb, Fe) in olivine. Redox effects are evidenced in various ways, and imply that Fe, Co conditions in the most FeO-poor melts. There is no obvious evidence for systematic variations in olivine

  13. ORIGINAL PAPER The legacy of crystal-plastic deformation in olivine

    E-print Network

    Jung, Haemyeong

    ORIGINAL PAPER The legacy of crystal-plastic deformation in olivine: high-diffusivity pathways Abstract Crystal-plastic olivine deformation to produce subgrain boundaries composed of edge dislocations is an inevitable consequence of asthenospheric mantle flow. Although crystal-plastic deformation

  14. Olivine friction at the base of oceanic seismogenic Margaret S. Boettcher,1,2

    E-print Network

    New Hampshire, University of

    Olivine friction at the base of oceanic seismogenic zones Margaret S. Boettcher,1,2 Greg Hirth,1 31 January 2007. [1] We investigate the strength and frictional behavior of olivine aggregates demonstrate that deformation was accommodated by frictional processes. Sample strengths were pressure

  15. Mineral replacement rate of olivine by chrysotile and brucite under high alkaline conditions

    E-print Network

    Montes-Hernandez, German

    Mineral replacement rate of olivine by chrysotile and brucite under high alkaline conditions Romain Available online 8 March 2012 Keywords: A1. Mineral replacement rate A1. Serpentinization A1. TG analyses B1. Alkaline medium B2. Chrysotile nanotubes a b s t r a c t Olivine mineral replacement by serpentine is one

  16. Olivine fabric transitions and shear wave anisotropy in the Ryukyu subduction system

    E-print Network

    Olivine fabric transitions and shear wave anisotropy in the Ryukyu subduction system Erik A fabrics with flow-parallel seismically fast directions to a flow-normal B-type olivine fabric in the cold fore-arc mantle of the Ryukyu wedge. We test the B-type fabric hypothesis by comparing observed

  17. The x ray microprobe determination of chromium oxidation state in olivine from lunar basalt and kimberlitic diamonds

    NASA Technical Reports Server (NTRS)

    Sutton, S. R.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    The synchrotron x-ray microprobe is being used to obtain oxidation state information on planetary materials with high spatial resolution. Initial results on chromium in olivine from various sources including laboratory experiments, lunar basalt, and kimberlitic diamonds are reported. The lunar olivine was dominated by Cr(2+) whereas the diamond inclusions had Cr(2+/Cr(3+) ratios up to about 0.3. The simpliest interpretation is that the terrestrial olivine crystallized in a more oxidizing environment than the lunar olivine.

  18. In situ observation of crystallographic preferred orientation of deforming olivine at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Ohuchi, Tomohiro; Nishihara, Yu; Seto, Yusuke; Kawazoe, Takaaki; Nishi, Masayuki; Maruyama, Genta; Hashimoto, Mika; Higo, Yuji; Funakoshi, Ken-ichi; Suzuki, Akio; Kikegawa, Takumi; Irifune, Tetsuo

    2015-06-01

    Simple-shear deformation experiments on polycrystalline olivine and olivine single-crystal were conducted at pressures of 1.3-3.8 GPa and temperatures of 1223-1573 K to understand the achievement of steady-state fabric strength and the process of dynamic recrystallization. Development of crystallographic preferred orientation (CPO) of olivine was evaluated from two-dimensional X-ray diffraction patterns, and shear strain was measured from X-ray radiographs. The steady-state fabric strength of the A-type fabric was achieved within total shear strain of ? = 2. At strains higher than ? = 1, an increase in concentration of the [0 1 0] axes mainly contributes to an increase in fabric strength. At strains higher than ? = 2, the magnitude of VSH/VSV (i.e., ratio of horizontally and vertically polarized shear wave velocities) scarcely increased in most of the runs. The VSH/VSV of peridotite (70 vol.% olivine + 30 vol.% minor phases) having the steady-state A-type olivine fabric coincides with that of recent global one-dimensional models under the assumption of horizontal flow, suggesting that the seismic anisotropy observed in the shallow upper mantle is mostly explained by the development of A-type olivine fabric. Experimental results on the deformation of single-crystal olivine showed that the CPO of olivine is influenced by the initial orientation of the starting single crystal because strain is concentrated in the recrystallized areas and the relic of the starting single crystal remains. In the upper mantle, the old CPO of olivine developed in the past may affect the olivine CPO developed in the present.

  19. Mantle-crust interactions in the oceanic lithosphere: Constraints from minor and trace elements in olivine

    NASA Astrophysics Data System (ADS)

    Sanfilippo, Alessio; Tribuzio, Riccardo; Tiepolo, Massimo

    2014-09-01

    Minor and trace element compositions of olivines are used as probes into the melt-rock reaction processes occurring at the mantle-crust transition in the oceanic lithosphere. We studied mantle and lower crustal sections from the Alpine Jurassic ophiolites, where lithospheric remnants of a fossil slow-spreading ocean are exposed. Olivines from plagioclase-harzburgites and replacive dunites (Fo = 91-89 mol%) and from olivine-rich troctolites and troctolites (Fo = 88-84 mol%) were considered. Positive correlations among the concentrations of Mn, Ni, Co, Sc and V characterize the olivines from the dunites. These chemical variations are reconciled with formation by melts produced by a mixed source consisting of a depleted peridotite and a pyroxene-rich, garnet-bearing component melted under different pressure conditions. We thereby infer that the melts extracted through these dunites channels were not fully aggregated after their formation into the asthenospheric mantle. Olivines from the olivine-rich troctolites and the troctolites are distinct by those in the dunites by lower Ni and higher concentrations of Mn and incompatible trace elements (Ti, Zr, Y and HREE). Fractional crystallization cannot reproduce the chemical variations of the olivines from the olivine-rich troctolites and the troctolites. In these rock-types, the olivines commonly show heterogeneous Ti, Zr, Y and HREE compositions, which produce variable Ti/Y and Zr/Y values. We correlate these olivine characteristics with events of reactive melt migration occurred during the formation of the primitive lower oceanic crust. We propose that the migrating melts formed at the mantle-crust transition via interaction with mantle peridotites during periods of low melt supply.

  20. Remote compositional analysis of lunar olivine-rich lithologies with Moon Mineralogy Mapper (M3) spectra

    USGS Publications Warehouse

    Isaacson, P.J.; Pieters, C.M.; Besse, S.; Clark, R.N.; Head, J.W.; Klima, R.L.; Mustard, J.F.; Petro, N.E.; Staid, M.I.; Sunshine, J.M.; Taylor, L.A.; Thaisen, K.G.; Tompkins, S.

    2011-01-01

    A systematic approach for deconvolving remotely sensed lunar olivine-rich visible to near-infrared (VNIR) reflectance spectra with the Modified Gaussian Model (MGM) is evaluated with Chandrayaan-1 Moon Mineralogy Mapper (M 3) spectra. Whereas earlier studies of laboratory reflectance spectra focused only on complications due to chromite inclusions in lunar olivines, we develop a systematic approach for addressing (through continuum removal) the prominent continuum slopes common to remotely sensed reflectance spectra of planetary surfaces. We have validated our continuum removal on a suite of laboratory reflectance spectra. Suites of olivine-dominated reflectance spectra from a small crater near Mare Moscoviense, the Copernicus central peak, Aristarchus, and the crater Marius in the Marius Hills were analyzed. Spectral diversity was detected in visual evaluation of the spectra and was quantified using the MGM. The MGM-derived band positions are used to estimate the olivine's composition in a relative sense. Spectra of olivines from Moscoviense exhibit diversity in their absorption features, and this diversity suggests some variation in olivine Fe/Mg content. Olivines from Copernicus are observed to be spectrally homogeneous and thus are predicted to be more compositionally homogeneous than those at Moscoviense but are of broadly similar composition to the Moscoviense olivines. Olivines from Aristarchus and Marius exhibit clear spectral differences from those at Moscoviense and Copernicus but also exhibit features that suggest contributions from other phases. If the various precautions discussed here are weighed carefully, the methods presented here can be used to make general predictions of absolute olivine composition (Fe/Mg content). Copyright ?? 2011 by the American Geophysical Union.

  1. Martian Dunite NWA 2737: Petrographic Constraints on Geological History, Shock Events, and Olivine Color

    SciTech Connect

    Treiman,A.; Dyar, M.; McCanta, M.; Noble, S.; Pieters, C.

    2007-01-01

    Meteorite Northwest Africa (NWA) 2737 is the second known chassignite, an olivine-rich igneous rock with mineral compositions and isotopic ratios that suggest it formed on Mars. NWA 2737 consists of ?85% vol. olivine (Mg, molar Mg/(Mg + Fe), of 78.3 {+-} 0.4%), which is notable because it is black in hand sample and brown in thin section. Other minerals include chromite, pyroxenes (augite, pigeonite, orthopyroxene), and diaplectic glass of alkali-feldspar composition. Aqueous alteration is minimal and appears only as slight dissolution of glass. NWA 2737 formed by accumulation of olivine and chromite from a basaltic magma; the other minerals represent magma trapped among the cumulus grains. Minerals are compositionally homogeneous, consistent with chemical equilibration in late and postigneous cooling. Two-pyroxene thermometry gives equilibration temperatures 1150 C, implying a significant time spent at the basalt solidus. Olivine-spinel-pyroxene equilibria give ?825 C (possibly the T of mesostasis crystallization) at an oxidation state of QMF-1. This oxidation state is consistent with low Fe3+ in olivine (determined by EMP, Moessbauer spectra, and synchrotron micro-XANES spectroscopy) and with {approx}10% of the iron in pyroxene being Fe3+. NWA 2737 experienced two shock events. The first shock, to stage S5-S6, affected the olivine by producing in it planar deformation features, intense mosaicism and lattice strain, and abundant droplets of iron-nickel metal, 5-15 nm in diameter. At this stage the olivine became deeply colored, i.e., strongly absorbing at visible and near-infrared (NIR) wavelengths. This shock event and its thermal pulse probably occurred at {approx}170 Ma, the Ar-Ar age of NWA 2737. The colored olivine is cut by ribbons of coarser, uncolored olivine with long axes along [100] and shorter axes on {l_brace}021{r_brace} planes: These are consistent with the easy slip law for olivine [100]{l_brace}021{r_brace}, which is activated at moderate strain rate at high temperature. Within these ribbons the olivine was coarsened and the iron metal globules coalesced to micron-sized grains. The ribbons also are mosaicized and cut by planar fractures, which bespeak a second shock event, possibly that of ejection from Mars. The deeply colored olivine in NWA 2737 is unusual and represents a new 'ground truth' type for remote sensing of Mars. Understanding the occurrence of the brown color in olivine in NWA 2737 places important constraints on interpretation of optical measurements.

  2. Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.

    1980-01-01

    The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

  3. Serpentinization of Sintered Olivine during Seawater Percolation Experiments

    NASA Astrophysics Data System (ADS)

    Luquot, L.; Andreani, M.; Godard, M.; Gouze, P.; Gibert, B.; Lods, G.

    2010-12-01

    Hydration of the mantle lithosphere exposed at slow spreading ridges leads to significant changes of the rock rheological, geophysical, mineralogical and geochemical properties, and to the production of large amounts of H2 and CH4, and of complex carbon molecules that support primitive ecosystems. The onset and efficiency of these hydrothermal processes requires penetration and renewal of fluids at the mineral-fluid interface. However, the mechanisms and the depth of fluid penetration are still poorly understood. Moreover, serpentinization is exovolumic, if a mass-conservative system is assumed, or chemical elements are leached out to conserve rock volume. Thus, the durability and extent of serpentinisation depends of the system capacity to create space and/or to drive mass transfers. In order to investigate these hydrodynamic and chemical mechanisms, we did a series of laboratory experiments during which seawater was injected in sintered San Carlos olivine samples at conditions representative of low temperature ultramafic hydrothermal systems. The percolation-reaction experiments were carried out using the ICARE 2 experimental bench at a confined pressure of 19 MPa and a temperature of 190°C; water flow was set at a constant specific discharge of 0.06 mL/h. During experiments (up to 23 days), permeability decreases continuously although the high Si concentrations in outlet fluids indicate steady olivine dissolution. Fluids are also depleted in Fe and Mg, suggesting precipitation of Fe- and Mg-rich mineral phases; SEM and AEM/TEM analyses of the reacted samples allowed to characterize hematite and poorly crystallized serpentine, both formed at the expense of olivine. Mass balance calculations indicate that, on average, 15 wt. % olivine was dissolved while the same mass of serpentine (+/- brucite) was formed; concurrently, porosity decreased from ~ 12% to 5 %. We infer that the structure of the newly formed serpentine resulted in the clogging of fluid paths and explain the decrease of permeability during experiments. Hematite (<1 wt.%) is also observed, indicating redox reactions. The estimated total hydrogen content of outlet fluids is 4.5 mmol/kg. Although these values are in the same range as those measured at the Lost City hydrothermal vent (e.g., Kelley et al, 2001), they are significantly lower than theoretical estimates of hydrogen composition of serpentinisation fluids (e.g., 21-170 mmol/kg, Wetzel & Shock, 2000). We infer that these differences result, in part, from poor fluid renewal at the mineral interface during experiments, and maybe also in natural systems. These experimental results are used to constrain numerical reactive transport models and better understand the scale and efficiency of serpentinization reactions (effective reaction rates in porous/fractured media) at the scale of spreading ridges. Ref.: Kelley et al., Nature, 412, 145-149, 2001; Wetzel & Shock, JGR, 105, 8319-8340, 2000.

  4. Phyllosilicate and Olivine around a Fracture in Nili Fossae

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) took this observation of part of the Nili Fossae region at the western margin of the Isidis impact basin at 3:07 (UTC) on December 12, 2006, near 21.9 degrees north latitude, 78.2 degrees east longitude. The image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 18 meters (60 feet) across. The image is about 11 kilometers (7 miles) wide at its narrowest point.

    The Isidis basin resulted from a gigantic impact on the surface of Mars early in the planet's history. The image of the Isidis basin at the top left is the colored elevation data from the Mars Orbiter Laser Altimeter (MOLA) overlain on a digital image mosaic from the Viking mission. Reds represent higher elevations, and blue lower elevations. The western rim of the Isidis basin has numerous, concentric troughs (or 'fossae') which may have formed during faulting associated with the impact event. Since then, the Nili Fossae region has since been heavily eroded, and is one of the most mineralogically diverse spots on Mars.

    This CRISM image targets one of region's smaller fractures. The image is shown overlain on the Viking digital image mosaic at lower left. The lower right CRISM image was constructed from three visible wavelengths (0.71, 0.60 and 0.53 microns in the red, green and blue image planes, respectively) and is close to what the human eye would see. The blue on the right of the image is an artifact from light scattering in the atmosphere. The upper right image was constructed from three infrared channels (2.38, 1.80 and 1.15 microns in the red, green and blue image planes, respectively) to highlight the mineralogy of the area. The bright green areas are rich in 'phyllosilicates,' a category of minerals including clays. The purple material along the walls of the fracture likely contains small amounts of the iron- and magnesium-rich mineral pyroxene. The yellow-brown material contains the iron- and magnesium-rich mineral olivine. Olivine and pyroxene are minerals associated with igneous activity.

    Overlaying CRISM data with images from the High-Resolution Imaging Science Experiment (HiRISE) camera shows that the phyllosilicates are in small, eroded outcrops of rock. The olivine is most abundant in sand dunes on the surface. The use of these two instruments together reveals more about the history of the region: Olivine sands covered the area shown in the image after the interaction of water and rock formed the phyllosilicates and after the fracture formed.

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

  5. Collisional Processing of Comet Surfaces: Impact Experiments into Olivine

    NASA Technical Reports Server (NTRS)

    Lederer, S. M.; Jensen, E. A.; Cintala, M. J.; Smith, D. C.; Nakamura-Messenger, K.; Keller, L. P.; Wooden, D. H.; Fernandez, Y. R.; Zolensky, M. E.

    2011-01-01

    A new paradigm has emerged where 3.9 Ga ago, a violent reshuffling reshaped the placement of small bodies in the solar system (the Nice model). Surface properties of these objects may have been affected by collisions caused by this event, and by collisions with other small bodies since their emplacement. In addition, objects in the Kuiper Belt are believed to undergo extensive collisional processing while in the Kuiper Belt. Physical manifestations of shock effects (e.g., planar dislocations) in minerals typically found in comets will be correlated with spectral changes (e.g. reddening, loss and shift of peaks, new signatures) to allow astronomers to better understand geophysical impact processing that has occurred on small bodies. Targets will include solid and granular olivine (forsterite), impacted over a range of impact speeds with the Experimental Impact Laboratory at NASA JSC. Analyses include quantification of the dependence of the spectral changes with respect to impact speed, texture of the target, and temperature.

  6. Serpentinization of sintered olivine during seawater percolation experiments

    NASA Astrophysics Data System (ADS)

    Luquot, Linda; Andreani, Muriel; Godard, Marguerite; Gouze, Philippe; Gibert, Benoit

    2010-05-01

    Hydration of the mantle lithosphere exposed along detachment faults at slow-spreading ridges leads to strong modification of rock rheological, geophysical and geochemical properties, and to the emission of large amounts of H2 and CH4, and of complex carbon molecules that support primitive ecosystems. The sustainability and efficiency of this hydration process, serpentinisation, and of associated reactions, requires penetration and renewal of fluids at the mineral-fluid interface. However, precipitation of material along flow paths will affect porosity and permeability that, in turn, will have feedbacks effects on the reactions. It is thus necessary to investigate the sustainability of flow paths, and the evolution of reaction rates for a dynamic system under representative conditions. We investigate these processes by percolation experiments carried out under P, T representative conditions, using the ICARE Microlab experimental bench. We present the preliminary results of seawater percolation within samples of sintered San Carlos olivine. The experiments were carried out under a confined pressure of 190 bars and a temperature of 190° C and water flow was set at a constant specific discharge of 0.06 ml/h.. The experiments were performed at very slow flow rate to be more representative of natural systems. ICARE Microlab allows measuring continuously the permeability changes during the percolation experiment and sampling the brine at the outlet of the sample. After 20 days of experiments, poorly crystallized serpentine and iron oxide formed within the micro-cracks while permeability strongly decreases. Such rapid precipitation of serpentine results in clogging of fluid paths. The chemical composition of the outlet fluid is dominated by Si and is depleted in Mg relative to stoechiometric dissolution of olivine during the whole experiment suggesting that brucite possibly formed. SEM and AEM/TEM are used to characterize the reactive interfaces and the neoformed materials.

  7. Stereochemically constrained complex organic molecules extracted from olivine crystal matrix

    NASA Astrophysics Data System (ADS)

    Gerasimenko, I.; Freund, F. T.; Imanaka, H.; Rodgers, R.

    2011-12-01

    Paradoxically, the dense solid state of magmatic minerals is a medium, in which organic synthesis can take place. The reason is that gas-fluid components such as H2O, CO/CO2/N2 and H2S are omnipresent in terrestrial magmatic environments. Any silicate mineral that crystallizes from such magmas will incorporate small quantities of the fluid-phase components in the form of structurally incompatible low-z impurities. During cooling the solute species undergo a redox conversion, resulting in chemically reduced low-z elements. To the extent that these low-z impurities are diffusively mobile, they will exsolve to the surface and/or to major structural defects inside the crystal matrix such as dislocations. Dislocations provide a 3-D structured environment, where the low-z impurities will tend to form stereochemically constrained polyatomic Cn-H-O-N-S entities, which we call organic protomolecules. In Nature, during weathering, such protomolecules will be released into the environment in the form of complex organic molecules. In our study we crush samples under clean conditions as a way to expose Cn-H-O-N-S entities at the fracture surfaces. We conduct identical experiments with selected large olivine single crystals, mm-sized olivine from peridiotite nodules from the San Carlos Volcanic Field, Arizona, and the vesiculated basalt that had carried the nodules upward in the volcanic conduit. We Soxhlet-extract the crushed powders with water, THF and ethyl acetate. The extracts are analyzed at the FTICR-MS facility at Florida State University using ultrahigh resolution Mass Spectrometry techniques capable of determining the chemical composition of the organic molecules up to 600 amu and more. So far we have found several analog sequences of oxygen-rich aliphatic hydrocarbons, families with up to 34 carbon atoms, probably poly-carboxylic acids, and some families containing sulfur.

  8. Olivine friction at the base of oceanic seismogenic zones

    USGS Publications Warehouse

    Boettcher, M.S.; Hirth, G.; Evans, B. M.

    2007-01-01

    We investigate the strength and frictional behavior of olivine aggregates at temperatures and effective confining pressures similar to those at the base of the seismogenic zone on a typical ridge transform fault. Triaxial compression tests were conducted on dry olivine powder (grain size ???60 ??m) at effective confining pressures between 50 and 300 MPa (using Argon as a pore fluid), temperatures between 600??C and 1000??C, and axial displacement rates from 0.06 to 60 ??m/s (axial strain rates from 3 ?? 10-6 to 3 ?? 10-3 s-1). Yielding shows a negative pressure dependence, consistent with predictions for shear enhanced compaction and with the observation that samples exhibit compaction during the initial stages of the experiments. A combination of mechanical data and microstructural observations demonstrate that deformation was accommodated by frictional processes. Sample strengths were pressure-dependent and nearly independent of temperature. Localized shear zones formed in initially homogeneous aggregates early in the experiments. The frictional response to changes in loading rate is well described by rate and state constitutive laws, with a transition from velocity-weakening to velocity-strengthening at 1000??C. Microstructural observations and physical models indicate that plastic yielding of asperities at high temperatures and low axial strain rates stabilizes frictional sliding. Extrapolation of our experimental data to geologic strain rates indicates that a transition from velocity weakening to velocity strengthening occurs at approximately 600??C, consistent with the focal depths of earthquakes in the oceanic lithosphere. Copyright 2007 by the American Geophysical Union.

  9. Effect of Sulfur on Siderophile Element Partitioning Between Olivine and Martian Primary Melt

    NASA Technical Reports Server (NTRS)

    Usui, T.; Shearer, C. K.; Righter, K.; Jones, J. H.

    2011-01-01

    Since olivine is a common early crystallizing phase in basaltic magmas that have produced planetary and asteroidal crusts, a number of experimental studies have investigated elemental partitioning between olivine and silicate melt [e.g., 1, 2, 3]. In particular, olivine/melt partition coefficients of Ni and Co (DNi and DCo) have been intensively studied because these elements are preferentially partitioned into olivine and thus provide a uniquely useful insight into the basalt petrogenesis [e.g., 4, 5]. However, none of these experimental studies are consistent with incompatible signatures of Co [e.g., 6, 7, 8] and Ni [7] in olivines from Martian meteorites. Chemical analyses of undegassed MORB samples suggest that S dissolved in silicate melts can reduce DNi up to 50 % compared to S-free experimental systems [9]. High S solubility (up to 4000 ppm) for primitive shergottite melts [10] implies that S might have significantly influenced the Ni and Co partitioning into shergottite olivines. This study conducts melting experiments on Martian magmatic conditions to investigate the effect of S on the partitioning of siderophile elements between olivine and Martian primary melt.

  10. Oxygen isotopic composition of relict olivine grains in cosmic spherules: Links to chondrules from carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Prasad, M. Shyam; Nagashima, K.; Jones, R. H.

    2015-09-01

    Most olivine relict grains in cosmic spherules selected for the present study are pristine and have not been disturbed during their atmospheric entry, thereby preserving their chemical, mineralogical and isotopic compositions. In order to understand the origin of the particles, oxygen isotope compositions of relict olivine grains in twelve cosmic spherules collected from deep sea sediments of the Indian Ocean were studied using secondary ion mass spectrometry. Most of the data lie close to the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line, with ?17O ranging from -5‰ to 0‰. The data overlap oxygen isotopic compositions of chondrules from carbonaceous chondrites such as CV, CK, CR and CM, which suggests that chondrules from carbonaceous chondrites are the source of relict grains in cosmic spherules. Chemical compositions of olivine in cosmic spherules are also very similar to chondrule olivine from carbonaceous chondrites. Several olivine relict grains in three cosmic spherules are 16O-rich (?17O -21.9‰ to -18.7‰), similar to oxygen isotopic compositions observed in calcium aluminum rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), and some porphyritic chondrules from carbonaceous chondrites. These grains appear to have recorded the initial oxygen isotopic composition of the inner solar nebula. Three olivine grains from two cosmic spherules have ?18O values >+20‰, which could be interpreted as mixing with stratospheric oxygen during atmospheric entry.

  11. Oxygen isotopic composition of individual olivine grains from the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Weinbruch, S.; Zinner, E. K.; El Goresy, A.; Steele, I. M.; Palme, H.

    1993-01-01

    The oxygen isotopic composition of a variety of individual olivine grains (including refractory forsterite grains, cores of isolated olivine grains, FeO-rich rims, and individual matrix olivine grains) from the Allende CV3 meteorite was investigated by ion microprobe mass spectrometry, in order to obtain information on the formation mechanism of these samples. It was found that the most primitive (i.e., refractory) olivine in Allende is far less enriched in O-16 than are spinel and pyroxene in Ca,Al-rich inclusions, suggesting that Allende olivine must have formed in an environment that is less enriched in O-16 compared to the gas from which Ca,Al-inclusions are formed. FeO-rich (26-30 wt pct) rims of isolated olivine grains are significantly higher in delta-O-17 and delta-O-18 than forsteritic cores, suggesting that these rims formed by condensation from an oxidized gas with higher delta-O-17 than delta-O-18. Matrix olivine was found to be highest in FeO and to have the lowest enrichment in O-16.

  12. Magnetic properties of natural and synthetic olivines: high-field measurements

    NASA Astrophysics Data System (ADS)

    Ferre, E. C.; Martin-Hernandez, F.

    2004-12-01

    Olivine [(Fex, Mg1-x)2 SiO4] is an orthosilicate solid solution between fayalite [Fe2 SiO4] and forsterite [Mg2 SiO4]. Olivine is a major constituent of the Earth mantle that is abundant in oceanic and continental peridotites and mantle xenoliths. The magnetic properties of olivines have been previously investigated using gem quality natural crystals known as peridots (Zabargad) or using laboratory grown synthetic crystals. Magnetic investigations are generally performed using low magnetic field or neutron diffraction techniques. Optical microscopy and TEM imagery reveal that most olivine crystals host iron oxides formed by exsolution during cooling. Theoretically, the magnetic susceptibility of olivine should decrease linearly from fayalite to fayalite as a function of the Fe content. The magnetic behavior should range from antiferromagnetic at high Fe content, paramagnetic at intermediate Fe contents and diamagnetic at very low Fe contents. New magnetic measurements, performed on various high field instruments (vibrating sample magnetometer, torque magnetometer, cantilever magnetometer), both on natural and synthetic samples, display ferromagnetic behavior, interpreted as due to the systematic presence of titanomagnetite inclusions in olivine crystals. These results emphasize the need to conduct measurements in high field in order to isolate the intrinsic paramagnetic properties of olivines. These measurements demonstrate the orthorhombic nature of the intrinsic paramagnetic properties, but also yield new data concerning the relationship between crystallographic axes, magnetic anisotropy and other physical anisotropies: [100] = K1, [010] = K2 and [001] = K3. Preliminary results also indicate substantial variations in degree of paramagnetic anisotropy (P) and paramagnetic shape factor (T). For Fo92, P = 1.359 and T = -0.845. These intrinsic paramagnetic properties are used to model the magnetic behavior of olivine across a range of temperatures relevant to planetary exploration. They are also used to evaluate the possible effects of olivine deformation on its intrinsic properties. For example, deformation-induced striped iron zoning is anticipated to strongly modify crystal magnetic anisotropy.

  13. Melt Connectivity and Its Effect on Grain Growth in Natural Olivine Aggregates: An Experimental Study

    NASA Astrophysics Data System (ADS)

    Hashim, L.; Sifre, D.; Précigout, J.; Gardés, E.; Le Trong, E.; Gaillard, F.

    2014-12-01

    To better constrain the rheology of the mantle, experimental studies on olivine grain growth have been conducted (Faul and Scott, 2006; Karato, 1989; Nichols and Mackwell, 1991) since the grain size is an important parameter under dynamic regimes (e.g. diffusion creep and grain boundary sliding). In order to better define the melt effect on the rheological response of a partially molten olivine aggregate, we have experimentally investigated the effect of melt on olivine grain growth and the connectivity of this melt phase. Experiments were performed in 3/4" piston cylinders at 500 MPa confining pressure, different temperatures (i.e. 1100°C, 1250°C and 1400°C) and four durations (1h, 12h, 72h and 15 days). Starting material was composed of natural San Carlos olivine (5 ?molivines were previously handpicked and annealed under controlled oxygen fugacity conditions close to the FMQ buffer. After the experiments, the melt connectivity was assessed through scanning electron microscope (SEM) images in backscattered electron mode. Electron backscatter diffraction (EBSD) maps of each sample were also collected in order to determine the olivine grain sizes as a function of time and melt content. References Faul, U. H., Scott, D., 2006. Grain growth in partially molten olivine aggregates. Contributions to Mineralogy and Petrology 151 (1), 101-111. Karato, S.-I., 1989. Grain growth kinetics in olivine aggregates. Tectonophysics 168 (4), 255-273. Nichols, S. J., Mackwell, S. J., 1991. Grain growth in porous olivine aggregates. Physics and Chemistry of Minerals 18 (4), 269-278. Sifré, D., Gardés, E., Massuyeau, M., Hashim, L., Hier-Majumder, S., Gaillard, F., 2014. Electrical conductivity during incipient melting in the oceanic low-velocity zone. Nature 509 (7498), 81-85.

  14. H Diffusion in Olivine and Pyroxene from Peridotite Xenoliths and a Hawaiian Magma Speedometer

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.; Bizimis, M.

    2014-01-01

    Hydrogen is present as a trace element in olivine and pyroxene and its content distribution in the mantle results from melting and metasomatic processes. Here we examine how these H contents can be disturbed during decompression. Hydrogen was analyzed by FTIR in olivine and pyroxene of spinel peridotite xenoliths from Salt Lake Crater (SLC) nephelinites which are part of the rejuvenated volcanism at Oahu (Hawaii) [1,2]. H mobility in pyroxene resulting from spinel exsolution during mantle upwelling Most pyroxenes in SLC peridotites exhibit exsolutions, characterized by spinel inclusions. Pyroxene edges where no exsolution are present have less H then their core near the spinel. Given that H does not enter spinel [3], subsolidus requilibration may have concentrated H in the pyroxene adjacent to the spinel exsolution during mantle upwelling. H diffusion in olivine during xenolith transport by its host magma and host magma ascent rates Olivines have lower water contents at the edge and near fractures compared to at their core, while the concentrations of all other chemical elements appear homogeneous. This suggests that some of the initial water has diffused out of the olivine. Water loss from the olivine is thought to occur during host-magma ascent and xenolith transport to the surface [4-6]. Diffusion modeling matches best the data when the initial water content used is that measured at the core of the olivines, implying that mantle water contents are preserved at the core of the olivines. The 3225 cm(sup -1) OH band at times varies independantly of other OH bands, suggesting uneven H distribution in olivine defects likely acquired during mantle metasomatism just prior to eruption and unequilibrated. Diffusion times (1-48 hrs) combined with depths of peridotite equilibration or of magma start of degassing allow to calculate ascent rates for the host nephelinite of 0.1 to 27 m/s.

  15. Minor and trace elements in olivines as probes into early igneous and mantle melting processes

    NASA Astrophysics Data System (ADS)

    Foley, Stephen F.; Prelevic, Dejan; Rehfeldt, Tatjana; Jacob, Dorrit E.

    2013-02-01

    The trace element composition of olivine is a rapidly growing research area that has several applications of great potential. Mantle olivines can be distinguished from volcanic olivines by lower concentrations of Ca (<700 ppm), Ti (<70 ppm), and often Cr. The melting of pyroxenites derived from recycled ocean crust can be recognized in volcanic olivines by correlations of Mn, Al, Sc and Co in addition to Ni. High Ni is characteristic of olivine derived from olivine-free source rocks, but alone it does not distinguish between recycling of ocean crust, continental crust, mantle wedge hybridization, and intra-mantle melt migration. Trace elements help to identify different types of non-peridotitic ultramafic rocks, including those not formed by ocean crust recycling. High Li may be caused by recycling of continental crust, as in Mediterranean post-collisional volcanics or by interaction with carbonatitic melts, and correlation with further elements such as Zn, Na, Ti and Ca will help to identify minerals in the source assemblages, such as phlogopite, spinel, garnet, amphiboles and carbonates, and thus the source of the olivine-free assemblages. Olivines often store the earliest chemical signals of melt loss in peridotites, but later absorb trace elements from passing melts, and are thus excellent monitors of the chemistry of metasomatic agents. Trace elements distinguish between Ti-enrichment by silicate melt metasomatism (high Ti, low Ca) and high-Ca signatures associated with plumes and rift regions that may be due to carbonate-silicate melts. Li may be enriched in olivine in the orogenic mantle, indicating the involvement of melted continental crustal material. Experimental data on element partitioning and diffusion currently partly conflicts with information from natural rocks.

  16. Using Diffusion Modeling to Understand Ni Variability and Magmatic Histories of Hawaiian Olivines

    NASA Astrophysics Data System (ADS)

    Lynn, K. J.; Garcia, M. O.; Shea, T.

    2014-12-01

    The Ni content of olivine has been used extensively for inferring the source lithology, and depth and temperature of generation for basaltic magma in various tectonic settings. Conflicting interpretations have been derived using Ni because Hawaiian basalts show large variations in olivine Ni content (up to a factor of two) for a given forsterite (Fo). A detailed study of historical basalts at Kilauea volcano was undertaken using high-precision EPMA to better understand the cause of Ni variation in Hawaiian basalts. Experimental studies predict that Ni abundance in olivine should be positively correlated with Fo during growth. Element maps and core-rim transects of crystals strongly zoned in Fo show that many Kilauea olivines violate this relationship. They have decoupled profiles in which Fo decreases towards the rim by up to 5 mol% and Ni remains nearly constant. Here, we evaluate whether the Ni variability and Fo-Ni decoupling result from (1) diffusive re-equilibration and/or (2) sectioning effects rather than being primary growth features of those olivines. We used 1D diffusion modeling of Mg, Ni, and Ca from EPMA profiles to determine if decoupling is caused by diffusive re-equilibration. Calculated timescales (e.g. 2.2-3.1 yr) are in excellent agreement for all elements and transects within individual crystals, suggesting that the Fo-Ni decoupling is a primary growth feature of the olivine. Sectioning effects on Fo-Ni zoning were evaluated using 3D diffusion models of numerical olivines, which were constructed using realistic morphologies found in nature. Off-center and highly oblique sections have Fo and Ni extremums offset from the geometric center in 2D sections. Analyses of normally zoned olivine with decoupled Fo-Ni will yield similar Ni at variable Fo, introducing "Ni-enriched", low Fo data. These "Ni-enriched" olivine compositions may contribute to the range of interpretations derived from current datasets

  17. Olivines in the Kaba carbonaceous chondrite and constraints on their formation

    NASA Technical Reports Server (NTRS)

    Hua, X.; Buseck, P. R.

    1993-01-01

    Kaba is unique in containing almost pure fayalitic olivine (Fo(sub 0.1)). Its coexistence with pure forsterite up to Fo(sub 99.6) and normal (Fo(sub 92) to Fo(sub 59)) and reversely (Fo(sub 0.4) to Fo(sub 4.7)) zoned olivines suggest that the Kaba olivines are in thermodynamic disequilibrium and experienced a complicated history. The fayalite is sufficiently pure that it is unlikely that it could have been produced by fractional crystallization. A gas-solid reaction under oxidizing conditions (H2O/H2 ratio approximately 10) is probably responsible for its formation.

  18. 3D Quantitative Confocal Laser Microscopy of Ilmenite Volume Distribution in Alpe Arami Olivine

    NASA Astrophysics Data System (ADS)

    Bozhilov, K. N.

    2001-12-01

    The deep origin of the Alpe Arami garnet lherzolite massif in the Swiss Alps proposed by Dobrzhinetskaya et al. (Science, 1996) has been a focus of heated debate. One of the lines of evidence supporting an exhumation from more than 200 km depth includes the abundance, distribution, and orientation of magnesian ilmenite rods in the oldest generation of olivine. This argument has been disputed in terms of the abundance of ilmenite and consequently the maximum TiO2 content in the discussed olivine. In order to address this issue, we have directly measured the volume fraction of ilmenite of the oldest generation of olivine by applying confocal laser scanning microscopy (CLSM). CLSM is a method which allows for three-dimensional imaging and quantitative volume determination by optical sectioning of the objects. The images for 3D reconstruction and measurements were acquired from petrographic thin sections in reflected laser light with 488 nm wavelength. Measurements of more than 80 olivine grains in six thin sections of our material yielded an average volume fraction of 0.31% ilmenite in the oldest generation of olivine from Alpe Arami. This translates into 0.23 wt.% TiO2 in olivine with error in determination of ±0.097 wt.%, a value significantly different from that of 0.02 to 0.03 wt.% TiO2 determined by Hacker et al. (Science, 1997) by a broad-beam microanalysis technique. During the complex geological history of the Alpe Arami massif, several events of metamorphism are recorded which all could have caused increased mobility of the mineral components. Evidence for loss of TiO2 from olivine is the tendency for high densities of ilmenite to be restricted to cores of old grains, the complete absence of ilmenite inclusions from the younger, recrystallized, generation of olivine, and reduction in ilmenite size and abundance in more serpentinized specimens. These observations suggest that only olivine grains with the highest concentrations of ilmenite are close to the original amount of TiO2 incorporated in the olivine. Our measurements show maximum volume fraction of ilmenite of 1.21%, corresponding to 0.9±0.38 wt.% of TiO2. Even the most conservative scenario reveals concentration of TiO2 in olivine of more than 0.5 wt.%, a value comparable to that reported by Dobrzhinetskaya et al. (1996) and an order of magnitude greater than any previous measurement of TiO2 in olivine. Experiments by Dobrzhinetskaya et al. (Chem. Geol, 2000) found that such high solubility can occur, but only at P>10GPa at mantle temperatures.

  19. Cellular Precipitates Of Iron Oxide in Olivine in a Stratospheric Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1996-01-01

    The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at approx. 1100 C during atmospheric entry flash (5-15 s) heating.

  20. Reactive flow as dominant evolution process in the lowermost oceanic crust: evidence from olivine of the Pineto ophiolite (Corsica)

    NASA Astrophysics Data System (ADS)

    Sanfilippo, Alessio; Tribuzio, Riccardo; Tiepolo, Massimo; Berno, Davide

    2015-10-01

    The Jurassic Pineto ophiolite from Corsica exposes a ~1-km-thick troctolite-olivine-gabbro sequence, interpreted to represent a lowermost sector of the gabbroic oceanic crust from a (ultra-)slow spreading system. To constrain the petrogenesis of the olivine-gabbros, minor and trace element analyses of olivine (forsterite = 84-82 mol%) were carried out. Olivine from the olivine-gabbros is depleted in incompatible trace elements (Sc, V, Ti, Y, Zr and heavy rare earth elements) with respect to olivines from associated troctolites. Depleted incompatible element compositions are also shown by olivine (forsterite = 86 mol%) from a clinopyroxene-rich troctolite. The incompatible element compositions of olivine argue against a petrogenetic process entirely driven by fractional crystallization. We propose that melts migrating through an olivine-plagioclase crystal mush chemically evolved by reaction with the existing minerals, changing in composition as it flowed upward. The melt residual from these interactions led to partial dissolution of preexisting olivine and to crystallization of clinopyroxene, generating olivine-gabbro bodies within a troctolite matrix. Reactive flow was the major evolution process active in the ~1-km crustal transect exposed at the Pineto ophiolite, producing lithological variations classically attributed to fractional crystallization processes.

  1. Cr, Mn, and Ca distributions for olivine in angritic systems: Constraints on the origins of Cr-rich and Ca-poor core olivine in angrite LEW87051

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Mckay, G.; Le, L.

    1994-01-01

    Angrite meteorites are a type of basaltic achondrites that are noted for their very old cyrstallization ages (4.55 b.y.) and unusual chemical and mineralogical properties. In spite of great interest, only four angrites have been found. LEW87051 is the smallest one which weighs 0.6 g. It is a porphyritic rock with coarse subhedral to euhedral olivines set in a fine-grained groundmass which clearly represents a crystallized melt. The largest uncertainty about the petrogenesis of LEW87051 is the relationship between the large olivine crystals and the groundmass. Prinz et al. suggests that olivines are xenocrysts, while McKay et al. proposed a fractional cyrstallization model based on experimental studies. However, the crystals have Cr-rich and Ca-poor cores which do not match experimental olivines. Although Jurewicz and McKay tried to explaine the zoning of the rim by diffusion, some features are not explained. There also exists a definite composition boundary of Fe(2+) and MnO between the core and the rim. To clarify the origin of these olivines, we have performed experiments using LEW87051 analogs to measure the effects of oxygen fugacity on distribution coefficients of various elements in an angritic system.

  2. An Olivine-Rich Crater in Tyrrhena Terra

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image of the ejecta of a crater in the Tyrrhena Terra region was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0328 UTC on February 23, 2007 (10:28 p.m. EST on February 22, 2007), near 13 degrees south latitude, 67 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 18 meters (60 feet) across. The region covered is roughly 9 kilometers (5.6 miles) wide at its narrowest point.

    Named for a classic albedo feature, Tyrrhena Terra is an extensive, heavily-cratered part of Mars' southern highlands, some 2,300 kilometers (1,430 miles) at its broadest extent. It is located to the northeast of the Hellas basin. The region imaged by CRISM is to the north of Hellas Planitia and just east of the crater Huygens in Tyrrhena Terra's western end.

    The uppermost image in the montage above reveals the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM image is located inside a large, flat-floored crater measuring about 52 kilometers (32 miles) across. The image includes a small crater and its ejecta blanket, an apron of material thrown out during a crater's formation, both located inside the larger crater.

    The lower left image is an infrared false-color image that reveals the extent of the ejecta blanket. It also includes ejecta from another small crater located just east of the CRISM image.

    The lower right image shows the strengths of mineral absorptions, and reveals the composition of the ejecta and surrounding material. The ejecta surrounding the small impact crater is thickest at the crater's rim, and becomes thinner to discontinuous at the blanket's outer edge. This small crater's ejecta blanket shows an enhanced spectral signature of the mineral olivine, as does the ejecta from the small crater just out of view to the east. In contrast the surrounding material is rich in the volcanic mineral pyroxene. This relationship demonstrates the layered characteristic of rocks forming the southern highlands: olivine-rich rock was buried by pyroxene-rich materials on the larger crater's floor, probably volcanic lavas. Later, the small crater penetrated the pyroxene-rich rock, excavated the underlying olivine-bearing unit, and deposited it as ejecta.

    CRISM is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and the Mars Science Laboratory for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter.

  3. Reinvestigation of the olivine-spinel transformation in Ni2SiO4 and the incongruent melting of Ni2SiO4 olivine

    NASA Technical Reports Server (NTRS)

    Ma, C.-B.

    1974-01-01

    The olivine-spinel transformation and the melting behavior of Ni2SiO4 were investigated over the PT ranges of 20-40 kbar, 650-1200 C, and 5-13 kbar, 1600-1700 C, respectively. It was confirmed that Ni2SiO4 olivine melts incongruently at high pressures and that it is a stable phase until melting occurs. The PT slope of the incongruent melting curve is approximately 105 bars/deg. The olivine-spinel transformation curve was shown to be a reversible univariant curve, and could be expressed by the linear equation P(bars) equals 23,300 + 11.8 x T(deg C). The transformation curve determined by Akimoto et al. (1965) is nearly parallel to that of the present work, but lies at pressures about 12% lower.

  4. Trace element composition of olivine - implications for the evolution of the olivine gabbro-troctolite-hosted Voisey's Bay Ni-Cu-Co sulfide deposit, Labrador

    NASA Astrophysics Data System (ADS)

    Bulle, F.; Layne, G. D.

    2011-12-01

    The Mesoproterozoic Voisey's Bay intrusion is part of the Nain Plutonic Suite, which transects the 1.85 Ga collisional boundary between the Proterozoic Churchill Province and the Archean Nain Province in Eastern Labrador. The intrusion comprises a group of troctolitic to olivine gabbroic bodies linked by olivine gabbro dikes; together these rocks host the world-class Voisey's Bay Ni-Cu-Co sulfide deposit. Zones of massive and disseminated sulfide mineralization (Reid Brook, Discovery Hill, Mini-Ovoid and Ovoid) occur within a dike and at the entry line of this dike into a larger intrusion termed the Eastern Deeps [1, 2, 3]. At least two pulses of magma have generated the intrusion and the associated sulfide mineralization; an initial surge that achieved sulfide saturation by interacting with upper crustal rocks, and a later pulse of fresh, undepleted magma that forced the initial magma upwards and both remobilized the immiscible sulfide liquid and upgraded it in metal content [1, 2, 3]. Previous research [1, 2] has shown that the Ni content of olivine from the distinct sulfide-bearing host rocks is highly variable, and also indicative of both magma mixing and interaction of silicate magmas with sulfide. To further validate the significance of the olivine chemistry as a tracer for ore-forming petrological processes, we have determined the abundances of Cr, Mn, Co, Ni, Zn in olivines from the various mafic lithologies of the Eastern Deeps intrusion using Secondary Ion Mass Spectrometry. We present systematic variations in Mn, Co, Ni and Zn with Fo-content in olivines for both sulfide-free and sulfide-bearing zones. Olivines from mineralized and brecciated troctolitic/gabbroic zones display significantly higher Mn (up to 11,000 ppm) and Zn (up to 550 ppm) concentrations than those from nominally barren counterparts. The barren troctolite, broadly termed normal troctolite (NT), is a petrographically homogenous plagioclase and olivine cumulate. However, olivine compositional data establish the presence of "reef-like" horizons with, for instance, elevated Ni concentrations (up to 2,500 ppm), versus surrounding horizons where values of ? 1,500 ppm are predominant. These horizons correspond with deflections in the whole-rock MgO, Fe2O3 and MnO contents. If these horizons are widespread and traceable laterally within the intrusion it would imply that: (1) a "cryptic-layering" might be preserved in olivines from the otherwise homogenous NT - indicating either crystallization from an input of fresh, undepleted mafic magma, or an interaction of those olivines with a Ni-rich sulfide liquid [1, 2], (2) the high Mn and Zn concentrations, coupled with lower forsterite values, are probably a result of crystallization from a country rock-contaminated mafic magma, and therefore, might act as a mineral-based indicator for the assimilation of upper crustal material. These observations may assist in developing a signature for olivines that have been in contact with highly contaminated (and thus potentially sulfide saturated) magmas. [1] Li et al. (2000) Econ. Geol. 95, 771-799. [2] Li and Naldrett (1999) Lithos 47, 1-31. [3] Lightfoot and Naldrett (1999) GAC Vol. 13, 1-30.

  5. Optical absorption and radiative heat transport in olivine at high temperature

    NASA Technical Reports Server (NTRS)

    Shankland, T. J.; Nitsan, U.; Duba, A. G.

    1979-01-01

    Results are presented of measurements of the optical absorption spectra (300-8000 nm) of olivine as a function of temperature (300-1700 K) under conditions of controlled and known oxygen fugacity within the stability field of the samples. The absorption spectra are used to calculate the temperature-dependent radiative transfer coefficient of olivine and to numerically study the accuracy of the method. The present absorption measurements in olivine under oxidizing conditions known to be within the olivine stability field indicate that the effective radiative conductivity K(R) is lower than that obtained in previous studies under different experimental conditions. The lower value of K(R) makes it more likely that some of the earth's internal heat is removed by convection and less likely that thermal models involving conduction and radiation alone will satisfactorily explain thermal conditions in the earth's mantle.

  6. FULL PAPER Open Access Characterization of olivine fabrics and mylonite in

    E-print Network

    Jung, Haemyeong

    of the surrounding anorthosite complex is displayed in ultramafic lenses as a modal variation in olivine, pyroxenes, and spinel, and the Caledonian eclogite-facies structure in the surrounding anorthosite gabbro is represented

  7. Petrography and olivine mineral chemistry of chondrules and inclusions in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Simon, S. B.; Haggerty, S. E.

    1979-01-01

    The examination of 19 polished-thin sections from a sample of the Allende meteorite reveals that anhedral olivine chondrules (OCs) are the most abundant chondrule type (19.7% of total chondrules + inclusions), followed by recrystallized OCs (7.5%), euhedral OCs (2.9%), glassy/skeletal OCs (2.7%), and barred OCs (2.3%). The most abundant inclusions are those comprised of many small olivine crystals with varying amounts of opaque minerals and glass (31.5%), followed by fine grained inclusions (16.1%) and single olivine crystals (15.7%). Microprobe analyses of olivines show that recrystallized and barred chondrules are the most forsteritic and exhibit relatively narrow compositional ranges, whereas single crystals have the widest range, from Fa sub 0.3 to Fa sub 49.

  8. Comparison of the Temperature Effects on Reflectance Spectra of Fresh and Experimentally Space Weathered Olivine

    NASA Astrophysics Data System (ADS)

    Corley, L. M.; Gillis-Davis, J. J.; Lucey, P. G.

    2015-11-01

    Reflectance spectra of fresh and laser irradiated olivine are measured at temperatures between 100–255 K to determine if an anticorrelation between temperature and reflectance in LOLA data is due to the influence of temperature on space weathering.

  9. Relation of the spectroscopic reflectance of olivine to mineral chemistry and some remote sensing implications

    NASA Technical Reports Server (NTRS)

    King, Trude V. V.; Ridley, W. Ian

    1987-01-01

    High-resolution visible and near-IR diffuse spectral reflectance are used to systematically investigate apparent wavelength shifts as a function of mineral chemistry in the Fe/Mg olivine series from Fo(11) to Fo(91). The study also shows that trace amounts of nickel can be spectrally detected in the olivine structure. Significant compositional information can only be extracted at relatively high resolution, because the overall spectral characteristics of the olivines change only subtly as a function of the Fe/Mg ratio. This laboratory study is expected to aid in the interpretation of remotely sensed data from both terrestrial and extraterrestrial bodies. Terrestrial applications may include the recognition of ultramafic, ultrabasic, and basaltic terrains which in themselves may have mineral potential. Among extraterrestrial applications, the asteroids are obvious candidates for further examination. Some permutations of Fe-Mg-Ni relations in olivines are discussed as they apply to the interpretation of asteroid surfaces and other extraterrestrial bodies.

  10. Simultaneous precipitation of magnesite and lizardite from hydrothermal alteration of olivine under high-carbonate alkalinity

    E-print Network

    Montes-Hernandez, German

    Simultaneous precipitation of magnesite and lizardite from hydrothermal alteration of olivine under alteration High-carbonate alkalinity Magnesite Lizardite Crystal growth Hydrothermal systems The present, competitive precipitation of magnesite and serpentine (preferentially lizardite type) was clearly determined

  11. Calorimetric Investigation of Olivine Carbonation as a mechanism of Carbon Sequestration

    E-print Network

    Qiu, Bo

    method due to the long-term stability of product minerals, magnesite and quartz. Examining reaction rate and thermodynamics of olivine-CO2-H2O reaction to form magnesite and quartz can provide data needed to determine

  12. Serpentine Mineral Replacements of Natural Olivine and their Seismic Implications: Oceanic

    E-print Network

    Demouchy, Sylvie

    that of the peridotite. These results have some relevance to the seismic anisotropy of serpen- tinized mantle. Anisotropy with increasing serpentinization. KEY WORDS: serpentinized peridotite; lizardite; antigorite^olivine topotaxy

  13. ELEMENTAL ABUNDANCE CONSTRAINTS ON CONDENSATION OF ALLENDE MATRIX OLIVINE. L. Grossman1

    E-print Network

    at 1450-1250K at reasonable nebular pressures, causing the co-condensing olivine to be pure forsterite+ to condense at equilibrium, it must diffuse into the interiors of previously condensed forsterite grains

  14. Are Megacrysts in Olivine-Phyric Shergottites Xenocrysts, Phenocrysts, or Something Else?

    NASA Astrophysics Data System (ADS)

    Balta, J. B.; McSween, H. Y.

    2011-03-01

    We argue based on detailed analyses and modeling of shergottite LAR 06319 that its olivines are antecrysts, formed from a melt similar to the current groundmass and entrained from a cumulate pile prior to eruption.

  15. Olivine-Orthopyroxene Equilibrium in Metal-rich Systems: Applications to Achondrites and Equilibrated Chondrites

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.; Benedix, G. K.; McCoy, T. J.

    2003-01-01

    Olivine and orthopyroxene are major minerals in every type of stony meteorite. The majority of achondritic meteorites and silicate-bearing iron meteorites have experienced high temperatures. If these temperatures persisted for an extended period of time then the iron contents of olivine and orthopyroxene should be in equilibrium. In their study of ungrouped clasts and chondritic meteorites, suggested that the equilibrium compositions of olivine and orthopyroxene should fall on a mixing line between LL chondrites and aubrites. Here we show that this is not necessarily the case and that a range of FeO contents in olivine and orthopyroxene can be in equilibrium with each other. The key parameters that determine the equilibrium Fe content in these minerals are temperature, oxygen fugacity (fO2), and silica activity (aSiO2).

  16. Systematic Ion Irradiation Experiments to Olivine: Comparison with Space Weathered Rims of Itokawa Regolith Particles

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Tsuchiyama, A.; Watanabe, N.; Yasuda, K.; Miyake, A.; Nakauchi, Y.; Okada, T.; Abe, M.; Yada, T.; Uesugi, M.; Karouji, Y.; Nakato, A.; Hashiguschi, M.; Kumagai, K.

    2015-11-01

    We performed H and He ion irradiation experiments using olivine fragments, in order to reveal formation time-scales of space weathered rims and formation processes of blisters by solar wind irradiation.

  17. First-principles investigation of Li intercalation kinetics in phospho-olivines

    E-print Network

    Malik, Rahul

    2013-01-01

    This thesis focuses broadly on characterizing and understanding the Li intercalation mechanism in phospho-olivines, namely LiFePO? and Li(Fe,Mn)PO?, using first-principles calculations. Currently Li-ion battery technology ...

  18. Phase behavior and phase transformation kinetics during electrochemical cycling of lithium transition metal olivine compounds

    E-print Network

    Meethong, Nonglak

    2009-01-01

    Olivine LiMPO4 (M = Fe, Mn, Co, Ni) compounds have received most attention from the battery research community as the cathodes for Li-ion batteries because of several advantages, including a high theoretical capacity, 170 ...

  19. An Interactive Computer Program for Simulating the Effects of Olivine Fractionation from Basaltic and Ultrabasic Liquids.

    ERIC Educational Resources Information Center

    Pearce, Thomas H.

    1983-01-01

    Describes interactive computer program (listing available from author) which simulates olivine fractionation from basaltic/ultrabasic liquid. The menu-driven nature of the program (for Apple II microcomputer) allows students to select ideal Rayleigh fractionation or equilibrium crystallization. (JN)

  20. Measurement of Activation Volume of Dry Olivine at High Pressure

    NASA Astrophysics Data System (ADS)

    Durham, W. B.; Kohlstedt, D. L.; Mei, S.; Dixon, D. A.; Wang, L.

    2007-12-01

    Despite considerable effort to measure the activation volume V* of creep of olivine using a new generation of high-pressure deformation machines, namely the Rotational Drickamer Apparatus (RDA) and the Deformation- DIA (D-DIA) in conjunction with synchrotron x-ray sources, progress has been marred by a combination of an apparently weak signal (i.e., low V*) and measurement noise. The latter has a broad spectrum of causes, from inherent limitations of measurement systems (of stress, primarily) to limited time available for creep experiments at synchrotron sources to investigator-induced variations of sample state during measurement. We report here measurements following a significant advance in regulation of sample state: deforming polycrystalline olivine in a dry state under more uniform mechanical conditions gives us our first clear signal of a positive activation volume. The advance has been made possible by a choice of assembly materials that assures anhydrous conditions around the sample, and a technique for testing in the absence of a thermocouple within the sample assembly. The key to the anhydrous assembly is a self-gasketing D-DIA cube of hybrid composition: a sphere of mullite embedded in a cube of unfired pyrophyllite, where the diameter of the sphere matches the edge length of the cube (6-mm in our case). Unfired pyrophyllite is an excellent gasketing material, being soft and (in notable contrast with mullite) non-friable. Additionally, as a cube-filling "web" around the mullite sphere, the pyrophyllite is ideally configured for D-DIA self gasketing: maximum volume at the cube corners, minimum (zero) volume at cube faces. Thus the configuration under pressure is a bone-dry mullite pressure medium gasketed by pyrophyllite. Removal of the thermocouple from the deformation piston results in a demonstrably more symmetric deformation column within the assembly for the entire duration of the experiment, and the absence of the thermocouple is reliably compensated by off-line calibration of furnace power vs temperature. Results of creep experiments in the new cell indicate a value of V*/n (where n is the stress exponent) of 3 ± 1 × 10-6 m3/mol between 3 and 6 GPa. The value of n will be better resolved in future experiments, but if the deformation is in the dislocation creep regime (n ~ 3.5), then V* ~ 10 × 10-6 m3/mol.

  1. Water in Olivine and its High-Pressure Polymorphs

    NASA Astrophysics Data System (ADS)

    Thomas, S. M.; Jacobsen, S. D.; Bina, C. R.; Reichart, P.; Moser, M.; Dollinger, G.; Hauri, E. H.

    2014-12-01

    Theory and high-pressure experiments imply a significant water storage capacity of nominally anhydrous minerals (NAMs), such as olivine, wadsleyite and ringwoodite, composing the Earth's upper mantle and transition zone to a depth of 660 km. The presence of water, dissolved as OH into such nominally anhydrous high-pressure silicates, notably influences phase relations, melting behavior, conductivity, elasticity, viscosity and rheology. The first direct evidence for hydration of the transition zone has recently been reported by Pearson et al. (2014) and Schmandt et al. (2014). Knowledge of absolute water contents in NAMs is essential for modeling the Earth's interior water cycle. To take advantage of IR spectroscopy as highly sensitive water quantification tool, mineral-specific absorption coefficients are required. Such calibration constants can be derived from hydrogen concentrations determined by independent techniques, such as secondary ion mass spectrometry (SIMS), Raman spectroscopy or proton-proton(pp)-scattering. Broad beam pp-scattering has been performed on double-polished mm-sized mineral platelets (Thomas et al. 2008), but until recently analysis was not feasible for smaller samples synthetized in high-pressure apparati. Here we present first results from pp-scattering microscopy studies on ?m-sized single crystals of hydrous olivine, wadsleyite and ringwoodite, which were synthesized at various pressure-temperature conditions in a multi-anvil press. The method allows us to quantify 3D distributions of atomic hydrogen in ?m dimensions. These self-calibrating measurements were carried out at the nuclear microprobe SNAKE at the Munich tandem accelerator lab using a 25 MeV proton microbeam. We provide hydrogen depth-profiles, hydrogen maps and H2O concentrations. Pp-scattering data and results from independent Raman and SIMS analyses are in good agreement. Water contents for a set of high-pressure polymorphs with varying Fe-concentrations range from 0.8 wt% to 2.5 wt% H2O. From experimental data for Fo83, Fo87, Fo90 and Fo100 compositions we calculate mineral-specific absorption coefficients for the quantification of H2O using IR-spectroscopy, compare them with previously estimated values and discuss IR calibrations for major phases of the Earth's mantle.

  2. Clast-laden nature and the origin of Luna 24 olivine-vitrophyres

    NASA Technical Reports Server (NTRS)

    Basu, A.; Mckay, D. S.; Fruland, R. M.

    1978-01-01

    The study shows that Luna 24 olivine-vitrophyric particles are actually fragments of clast-laden melt and are not from a very low titanium (VLT) mare basalt flow. Diversity of composition and clast population, and morphological similarity to ropy glasses suggest an impact melt origin. Compositionally, the olivine-vitrophyres resemble the high magnesian VLT basalts, which may have been the target and source of the impact melt.

  3. Chemical zoning and homogenization of olivines in ordinary chondrites and implications for thermal histories of chondrules

    NASA Technical Reports Server (NTRS)

    Miyamoto, Masamichi; Mckay, David S.; Mckay, Gordon A.; Duke, Michael B.

    1986-01-01

    The extent and degree of homogenization of chemical zoning of olivines in type 3 ordinary chondrites is studied in order to obtain some constraints on cooling histories of chondrites. Based on Mg-Fe and CaO zoning, olivines in type 3 chondrites are classified into four types. A single chondrule usually contains olivines with the same type of zoning. Microporphyritic olivines show all four zoning types. Barred olivines usually show almost homogenized chemical zoning. The cooling rates or burial depths needed to homogenize the chemical zoning are calculated by solving the diffusion equation, using the zoning profiles as an initial condition. Mg-Fe zoning of olivine may be altered during initial cooling, whereas CaO zoning is hardly changed. Barred olivines may be homogenized during initial cooling because their size is relatively small. To simulated microporphyritic olivine chondrules, cooling from just below the liquidus at moderately high rates is preferable to cooling from above the liquidus at low rates. For postaccumulation metamorphism of type 3 chondrites to keep Mg-Fe zoning unaltered, the maximum metamorphic temperature must be less than about 400 C if cooling rates based on Fe-Ni data are assumed. Calculated cooling rates for both Fa and CaO homogenization are consistent with those by Fe-Ni data for type 4 chondrites. A hot ejecta blanket several tens of meters thick on the surface of a parent body is sufficient to homogenize Mg-Fe zoning if the temperature of the blanket is 600-700 C. Burial depths for petrologic types of ordinary chondrites in a parent body heated by Al-26 are broadly consistent with those previously proposed.

  4. Effect of metamorphism on isolated olivine grains in CO3 chondrites

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.

    1993-01-01

    The presence of a metamorphic sequence in the CO3 chondrite group has been shown previously to result in changes in properties of chondrule silicates. However, the role of isolated olivine grains during metamorphism of these chondrites has not been addressed. Isolated olivine grains in two metamorphosed CO3 chondrites, Lance and Isna, have been investigated in this study in order to assess the compositional properties of isolated olivine grains that may be attributable to metamorphism. Compositional changes in isolated olivines with increasing petrologic subtype are very similar to changes in chondrule olivines in the same chondrites. Olivine compositions from all occurrences (chondrules, isolated grains, and matrix) converge with increasing petrologic subtype. The degree of equilibration of minor elements is qualitatively related to the diffusion rate of each element in olivine, suggesting that diffusion-controlled processes are the most important processes responsible for compositional changes within the metamorphic sequence. The data are consistent with metamorphism taking place in a closed system on the CO3 chondrite parent body. Fe-poor olivine grains in metamorphosed chondrites are characterized by an Fe-rich rim, which is the result of diffusion of Fe into the grains from Fe-rich matrix. In some instances, 'complex', Fe-rich rims have been identified, which appear to have originated as igneous overgrowths and subsequently to have been overprinted by diffusion processes during metamorphism. Processes experienced by CO3 chondrites are more similar to those experienced by the ordinary chondrites than to those encountered by other carbonaceous chondrites, such as the CV3 group.

  5. Angrite LEW87051: Are the olivines pheno's or xeno's? A continuing story

    NASA Technical Reports Server (NTRS)

    Jurewicz, A. J. G.; Mckay, G. A.

    1993-01-01

    The achondrite LEW87051 is a porphyritic basalt consisting of large subhedral to euhedral zoned olivines in a finer-grained groundmass. The texture of this groundmass looks remarkably like a quenched melt. However, although the rock is clearly igneous, its exact origins and history are under dispute. From petrographic observations, Prinz felt that the large olivines were xenocrysts and that the zoning reflected interaction with an unrelated, CAI-enriched melt. McKay et al. was able to model the olivines as phenocrysts, whose zoning was the result of a parent melt that changed in composition as material crystallized, e.g., fractional crystallization in a closed system, and calculated a parent melt composition. Jurewicz and McKay compared the calculated parent melt composition with actual partial melts from CV and CM chondrites. They showed that the calculated melt was substantially different from equilibrium melts of these chondrites; however, the LEW87051 groundmass composition was similar to some of the low temperature partial melts, although slightly enriched in AN (or depleted in OL) components. This study presents the results of an independent petrologic look at other olivines in LEW87051 and the preliminary results of a quantitative model for the major zoning in these olivines as diffusive-exchange with an olivine-saturated, low temperature angritic melt.

  6. Single-Crystal Elasticity of San Carlos Olivine in the Earth's Mantle

    NASA Astrophysics Data System (ADS)

    Mao, Z.; Lin, J. F.; Fan, D.; Yang, J.; Zhuravlev, K. K.; Tkachev, S. N.

    2014-12-01

    Olivine is the most abundant mineral in the Earth's upper mantle. Studies on the elasticity of olivine attracted extensive research interests in the past few decades and have provided important constraints on the composition and structure of the Earth's upper mantle. Of particular importance is the single-crystal elasticity of olivine which is essential for understanding the anisotropy structure of the upper mantle. However, previous experimental studies on the single-crystal elasticity of olivine are limited to high pressure and ambient temperature or high temperature and ambient pressure. Much of our current knowledge on the velocity and anisotropy structures of the upper mantle heavily relies on extrapolations of limited experimental results. Here, we have studied the single-crystal elasticity of San Carlos olivine, [(Mg0.9Fe0.1)2SiO4], up to 20 GPa and 900 K using Brillouin spectroscopy and X-ray diffraction in an externally-heated diamond anvil cell at GSECARS of the Advanced Photon Source, Argonne National Laboratory. The simultaneously high pressure-temperature experiments allow us to investigate the combined effect of pressure and temperature on the velocity and anisotropy of olivine. These results have been applied to model the velocity structure, Vp and Vs anisotropy, Vp/Vs ratio, and Poisson's ratio of the Earth's upper mantle. Comparing the modeling results with seismic observations allow us to have a more comprehensive understanding on the velocity and anisotropy structure of the Earth's upper mantle.

  7. A comparison of FeO-rich, porphyritic olivine chondrules in unequilibrated chondrites and experimental analogues

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.; Lofgren, Gary E.

    1993-01-01

    Experimentally produced analogues of porphyritic olivine (PO) chondrules in ordinary chondrites provide an important insight into chondrule formation processes. We have studied experimental samples with PO textures grown at three different cooling rates (2, 5 and 100 C/h), and samples that have been annealed at high temperatures (1000-1200 C) subsequent to cooling. These are compared with natural chondrules of similar composition and texture from the ordinary chondrites Semarkona (LL3.0) and ALH 81251 (LL3.3). Zoning properties of olivine grains indicate that the Semarkona chondrules cooled at comparable rates to the experiments. Zoning in olivine from chondrules in ALH 81251 is not consistent with cooling alone but indicates that the chondrules underwent an annealing process. Chromium loss from olivine is very rapid during annealing and calculated diffusion coefficients for Cr in olivine are very similar to those of Fe-Mg interdiffusion coefficients under the same conditions. Annealed experimental samples contain an aluminous, low-Ca pyroxene which forms by reaction of olivine and liquid. No similar reaction texture is observed in ALH 81251 chondrules, and this may be evidence that annealing of the natural samples took place at considerably lower temperatures than the experimental analogues. The study supports the model of chondrule formation in a cool nebula and metamorphism of partly equilibrated chondrites during reheating episodes on the chondrite parent bodies.

  8. Particle dynamics and aggregation of crystals in a magma chamber with application to Kilauea Iki olivines

    NASA Astrophysics Data System (ADS)

    Schwindinger, Kathleen R.

    1999-03-01

    Crystals settling in relative proximity to each other will settle faster than their respective Stokes' velocities ( US) due to their mutual interactions. Pairs of equant spheres (within 100 diameters of each other) are accelerated to 1.55 US. Modification of Han and Lawler's [Han, M., Lawler, D.F., 1991. Interactions of two settling spheres: settling rates and collision efficiency. Journal of Hydraulic Engineering 117 (10) 1269-1289] equations to include inertia shows that the velocities of a pair of spheres differ and change during descent, allowing them to come into contact. In quiescent settling experiments with olivine-shaped clay prisms, the pairs of prisms usually settled faster than their US. The clay prisms aggregated 80% of the time, with the pairs of prisms rotating and tumbling as they fall, coming into and out of contact. Size variations in Kilauea Iki olivines control aggregation during quiescent settling. The settling velocities of individual crystals are variable, increasing when they are incorporated into aggregates. A suspension of olivine crystals (more than 0.01 vol.%) in a magma will settle slower than the average Stokes' velocities, except when a buoyant phase is present. Addition of a buoyant phase, such as CO 2 bubbles, can increase the settling velocity of the olivines when the total concentration (olivine plus bubbles) ( ?) is <35%, or carry the olivines in a packed bed when ?>35%.

  9. Characterization and Petrologic Interpretation of Olivine-Rich Basalts at Gusev Crater, Mars

    NASA Technical Reports Server (NTRS)

    McSween, H. Y.; Wyatt, M. B.; Gellert, R.; Bell, J. F., III; Morris, R. V.; Herkenhoff, K. E.; Crumpler, L. S.; Milam, K. A.; Stockstill, K. R.; Tornabene, L. L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N. A.; Christensen, P. R.; Clark, B. C.; Crisp, A.; DesMarais, D. J.; Economou, T.; Farmer, J. D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.

    2006-01-01

    Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and shergottites appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and shergottites in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times.

  10. Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars

    USGS Publications Warehouse

    McSween, H.Y.; Wyatt, M.B.; Gellert, Ralf; Bell, J.F.; Morris, R.V.; Herkenhoff, K.E.; Crumpler, L.S.; Milam, K.A.; Stockstill, K.R.; Tornabene, L.L.; Arvidson, R.E.; Bartlett, P.; Blaney, D.; Cabrol, N.A.; Christensen, P.R.; Clark, B.C.; Crisp, J.A.; Des Marais, D.J.; Economou, T.; Farmer, J.D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.; Hamilton, V.E.; Johnson, J.R.; Joliff, B.L.; Klingelhofer, G.; Knudson, A.T.; McLennan, S.; Ming, D.; Moersch, J.E.; Rieder, R.; Ruff, S.W.; Schrorder, C.; de Souza, P.A.; Squyres, S.W.; Wanke, H.; Wang, A.; Yen, A.; Zipfel, J.

    2006-01-01

    Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and shergottites appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and shergottites in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times. Copyright 2006 by the American Geophysical Union.

  11. Geochemistry and origin of metal, olivine clasts, and matrix in the Dong Ujimqin Qi mesosiderite

    NASA Astrophysics Data System (ADS)

    Kong, Ping; Su, Wen; Li, Xianhua; Spettel, Bernhard; Palme, Herbert; Tao, Kejie

    2008-03-01

    The Dong Ujimqin Qi mesosiderite is the first recorded fall of a stony-iron meteorite in China. According to silicate textures and metal composition, this meteorite is classified as a member of subgroup IB. Instrumental neutron activation analyses (INAA) of metals show that the matrix metal has lower concentrations of Os, Ir, Re, and Pt, but higher concentrations of Ni and Au than the 7.5 cm metal nodule present in the meteorite. We attribute these compositional differences to fractional crystallization of molten metal. Studies of olivine clasts show that FeO contents are uniform in individual olivine crystals but are variable for different olivine clasts. Although concentrations of rare earth elements (REEs) change within olivine clasts, they all exhibit a vee-shaped pattern relative to CI chondrites. The relatively high concentrations of REEs in olivine and the shape of REE patterns require a liquid high in REEs and especially in light REEs. As such a liquid was absent from the region where basaltic and gabbroic clasts formed, mesosiderite olivine must have formed in a part of the differentiated asteroid that is different from the location where other mesosiderite silicate clasts formed.

  12. Disclinations provide the missing mechanism for deforming olivine-rich rocks in the mantle.

    PubMed

    Cordier, Patrick; Demouchy, Sylvie; Beausir, Benoît; Taupin, Vincent; Barou, Fabrice; Fressengeas, Claude

    2014-03-01

    Mantle flow involves large strains of polymineral aggregates. The strongly anisotropic plastic response of each individual grain in the aggregate results from the interactions between neighbouring grains and the continuity of material displacement across the grain boundaries. Orthorhombic olivine, which is the dominant mineral phase of the Earth's upper mantle, does not exhibit enough slip systems to accommodate a general deformation state by intracrystalline slip without inducing damage. Here we show that a more general description of the deformation process that includes the motion of rotational defects referred to as disclinations can solve the olivine deformation paradox. We use high-resolution electron backscattering diffraction (EBSD) maps of deformed olivine aggregates to resolve the disclinations. The disclinations are found to decorate grain boundaries in olivine samples deformed experimentally and in nature. We present a disclination-based model of a high-angle tilt boundary in olivine, which demonstrates that an applied shear induces grain-boundary migration through disclination motion. This new approach clarifies grain-boundary-mediated plasticity in polycrystalline aggregates. By providing the missing mechanism for describing plastic flow in olivine, this work will permit multiscale modelling of the rheology of the upper mantle, from the atomic scale to the scale of the flow. PMID:24572356

  13. Disclinations provide the missing mechanism for deforming olivine-rich rocks in the mantle

    NASA Astrophysics Data System (ADS)

    Cordier, Patrick; Demouchy, Sylvie; Beausir, Benoît; Taupin, Vincent; Barou, Fabrice; Fressengeas, Claude

    2014-03-01

    Mantle flow involves large strains of polymineral aggregates. The strongly anisotropic plastic response of each individual grain in the aggregate results from the interactions between neighbouring grains and the continuity of material displacement across the grain boundaries. Orthorhombic olivine, which is the dominant mineral phase of the Earth's upper mantle, does not exhibit enough slip systems to accommodate a general deformation state by intracrystalline slip without inducing damage. Here we show that a more general description of the deformation process that includes the motion of rotational defects referred to as disclinations can solve the olivine deformation paradox. We use high-resolution electron backscattering diffraction (EBSD) maps of deformed olivine aggregates to resolve the disclinations. The disclinations are found to decorate grain boundaries in olivine samples deformed experimentally and in nature. We present a disclination-based model of a high-angle tilt boundary in olivine, which demonstrates that an applied shear induces grain-boundary migration through disclination motion. This new approach clarifies grain-boundary-mediated plasticity in polycrystalline aggregates. By providing the missing mechanism for describing plastic flow in olivine, this work will permit multiscale modelling of the rheology of the upper mantle, from the atomic scale to the scale of the flow.

  14. Water in Pyroxene and Olivine from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.

    2012-01-01

    Water in the interior of terrestrial planets can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) like olivine, pyroxene, or feldspar [1-3]. Although these minerals contain only tens to hundreds of ppm H2O, this water can amount to at least one ocean in mass when added at planetary scales because of the modal dominance of NAM in the mantle and crust [4]. Moreover these trace amounts of water can have drastic effects on melting temperature, rheology, electrical and heat conductivity, and seismic wave attenuation [5]. There is presently a debate on how much water is present in the martian mantle. Secondary ionization mass spectrometry (SIMS) studies of NAM [6], amphiboles and glass in melt inclusions [7-10], and apatites [11, 12] from Martian meteorites report finding as much water as in the same phases from Earth's igneous rocks. Most martian hydrous minerals, however, generally have the relevant sites filled with Cl and F instead of H [13, 14], and experiments using Cl [15] in parent melts can reproduce Martian basalt compositions as well as those with water [16]. We are in the process of analyzing Martian meteorite minerals by Fourier transform infrared spectrometry (FTIR) in order to constrain the role of water in this planet s formation and magmatic evolution

  15. Steady diffusion model for olivine-plagioclase corona growth

    NASA Astrophysics Data System (ADS)

    Nishiyama, Tadao

    1983-02-01

    This paper describes an application of a steady diffusion model ( JOESTEN, 1977) to an olivineplagioclase corona and some new results about a theoretical background on the steady diffusion equations. The olivine-plagioclase corona in a metanorite from Mt. Ikoma. Japan, has a layer sequence of olivinecummingtonite-hornblende + spinel-plagioclase. An analysis of a set of steady diffusion equations for the corona in the four-component system, MgO-AlO 3/2-SiO 2-Na 0.1Ca 0.9O 0.95 (NC) with excess H 2O. successfully gives the exchange cycle ( FISHER, 1973) in the layer sequence with specific values of the phenomenological coefficients' ratios; L MgMg/L SiSi, L MgMg/L AlAl and L MgMg/L NCNC. The factor which controls most strictly the stability of the layer sequence under isobaric-isothermal conditions is L MgMg/L AlAl. Theoretical considerations on the steady diffusion equations show that the L-ratios does not depend on concentrations even if the phenomenological coefficients themselves are functions of concentrations. Equivalence of the steady state condition and the minimum rate of entropy production law ( PRIGOGINE, 1967) is also proved for the system with fixed chemical potential gradients under isobaric-isothermal conditions, such as reaction bands. These results give a strong background for the model.

  16. Diffusion modelling of coronas around olivine in an open system

    NASA Astrophysics Data System (ADS)

    Ashworth, J. R.; Birdi, J. J.

    1990-09-01

    An open-system modification is introduced to Joesten's theory for steady-state diffusion-controlled growth of layered structures. The modified theory produces a model which is fully consistent with data for coronas between olivine and plagioclase from NE Scotland, having the layer sequence Pl|Hbl + Spl|Hbl|Opx|Ol. Relative immobility of Al and Si, inferred from the two-mineral symplectite, leads to the useful approximation of closure to Al and Si. The resulting model is consistent with Al, Si immobility, because it requires an Onsager diffusion coefficient for Al ( LAlAl) lower by an order of magnitude than that for Mg, while L AlAl/L SiSi?1 . Iron is less constrained than Mg to be mobile, with Ca and Na unconstrained, because their fluxes are relatively small. The results are insensitive to small errors in the data, except in Al and Si contents. Low Al/Si in plagioclase, as an example, requires lower L AlAl/L SiSi in the model. Variation of metasomatic inputs can explain the layer sequence Pl|Hbl + Spl|Opx + Spl|Opx|Ol, reported in the literature but not accounted for by the more restricted version of the theory previously available. The modified theory remains simple, and is likely to be applicable to other coronas, though complex examples may reveal its limitations.

  17. Reaction rim growth on olivine in silicic melts: Implications for magma mixing

    USGS Publications Warehouse

    Coombs, M.L.; Gardner, J.E.

    2004-01-01

    Finely crystalline amphibole or pyroxene rims that form during reaction between silicic host melt and cognate olivine xenocrysts, newly introduced during magma mixing events, can provide information about the timing between mixing and volcanic eruptions. We investigated rim growth experimentally by placing forsteritic olivine in rhyolitic and rhyodacitic melts for times between 25 and 622 h at 50 and 150 MPa, H2O-saturated, at the Ni-NiO buffer. Rims of orthopyroxene microlites formed from high-silica rhyolite and rhyodacite melts at 885??C and 50 MPa, and in the rhyolite at 150 MPa and 885??C. Rims of amphibole with lesser orthopyroxene formed in the rhyolite at 150 MPa and 800??C and in the rhyodacite at 150 MPa and 885??C. Irregular, convolute olivine edges and mass balance between olivine, melt, and rim phases show that olivine partly dissolved at all conditions. Iron-rich zones at the exteriors of olivines, which increased in width parabolically with time, show that Fe-Mg interdiffusion occurring in olivines was not outpaced by olivine dissolution. Linear increases of the square of rim widths with time suggest that diffusion within the melt is the rate-controlling process for olivine dissolution and rim growth. Rims grew one-half to one order-of-magnitude faster when melt water contents were doubled, unless conditions were far above the liquidus. Rim growth rate in rhyolite increases from 0.055 ?? 0.01 ??m2/h at 885 ??C and 50 MPa to 0.64 ?? 0.13 ??m2/h at 800 ??C and 150 MPa. Melt composition has a lesser effect on rim growth rates, with growth rate increasing as melt SiO2 content decreases. Pyroxene rims on olivines in andesite erupted from Arenal volcano (Costa Rica) grew at a rate of 3.0 ?? 0.2 ??m2/h over an eleven-year period. This rate is faster than those of the experiments due to lower melt viscosity and higher temperatures, and suggests that a magma mixing event preceded the start of the eruption by days.

  18. Temperature Dependence and Recoil-free Fraction Effects in Olivines Across the Mg-Fe Solid Solution

    NASA Technical Reports Server (NTRS)

    Sklute, E. C.; Rothstein, Y.; Dyar, M. D.; Schaefer, M. W.; Menzies, O. N.; Bland, P. A.; Berry, F. J.

    2005-01-01

    Olivine and pyroxene are the major ferromagnesian minerals in most meteorite types and in mafic igneous rocks that are dominant at the surface of the Earth. It is probable that they are the major mineralogical components at the surface of any planetary body that has undergone differentiation processes. In situ mineralogical studies of the rocks and soils on Mars suggest that olivine is a widespread mineral on that planet s surface (particularly at the Gusev site) and that it has been relatively unaffected by alteration. Thus an understanding of the characteristics of Mossbauer spectra of olivine is of great importance in interpreting MER results. However, variable temperature Mossbauer spectra of olivine, which are needed to quantify recoil-free fraction effects and to understand the temperature dependence of olivine spectra, are lacking in the literature. Thus, we present here a study of the temperature dependence and recoil-free fraction of a series of synthetic olivines.

  19. Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures

    NASA Technical Reports Server (NTRS)

    Longazo, Teresa G.; Wentworth, Susan J.; Clemett, Simon J.; Southam, Gordon; McKay, David S.

    2001-01-01

    We are investigating the weathering of silicate minerals by both purely inorganic, and biologically mediated processes using field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDS). By resolving surface textures and chemical compositions of weathered surfaces at the sub-micron scale we hope to be able to distinguish abiotic from biotic weathering processes and so establish a new biosignature applicable to the study of astromaterials including but not limited to the Martian meteorites. Sterilized olivine grains (San Carlos, Arizona) no more than 1-2 mm in their longest dimension were optically assayed to be uniform in color and free of inclusions were selected as weathering subjects. Prior to all experiments surface morphologies and Fe/Mg ratios were determined for each grain using FE-SEM and EDS. Experiments were divided into two categories abiotic and biotic and were compared with "naturally" weathered samples. For the preliminary experiments, two trials (open and closed to the ambient laboratory environment) were performed under abiotic conditions, and three trials under biotic conditions (control, day 1 and day 2). The open system abiotic trials used sterile grains heated at 98 C and 200 C for both 24 and 48 hours in 1L double distilled de-ionized water. The closed system abiotic trials were conducted under the same conditions but in a sealed two layer steel/Teflon "bomb" apparatus. The biotic trials used sterile grains mounted in a flow-through device attached to a wellhead on the Columbia River aquifer. Several discolored, altered, grains were selected to document "natural" weathering surface textures for comparison with the experimental samples. Preliminary results indicate there are qualitative differences in weathered surface textures among all the designed experiments. The olivine grains in abiotic trials displayed etching, pitting, denticulate margins, dissolution and clay formation. The scale of the features ranged from tens to a few microns with textures that remained relatively sharp and were crystallographically controlled. These results were comparable to that observed in the "naturally" weathered comparison/reference grains. Chemical analysis by EDS indicates these textures correlated with the relative loss of Mg and Fe cations by diffusional processes. In contrast the biotic results indicated changes in the etching patterns on the scale of hundreds of nm, which are neither sharp nor crystallographically controlled (nanoetching). Organisms, organic debris and/or extracellular polymeric substances (biofilm) were often in close proximity or direct contact with the nanoetching. While there are many poorly constrained variables in natural weathering experiments to contend with, such as the time scale, the chemistry of the fluids and degree of biologic participation, some preliminary observations can be made: (1) certain distinct surface textures appear correlated with the specific processes giving rise to these textures; (2) the process of diffusing cations can produce many similar styles of surface textural changes; and (3) the main difference between abiotic and biotically produced weathering is the scale (microns versus nanometers) and the style (crystallographically versus noncrystallographically controlled) of the textural features. Further investigation into nanosize scale surface textures should attempt to quantify both textures and chemical changes of the role of microorganisms in the weathering of silicates. Additional experiments addressing nanoscale textures of shock features for comparison with the current data set.

  20. Experimental constraints on formation of hematite in olivine at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Zhang, Yanfei; Wang, Chao; Wu, Yao; Liu, Wenlong; Jin, Zhenmin

    2015-10-01

    Iron-rich oxides, such as magnetite or hematite, have been reported in olivine grains in many orogenic garnet peridotites from continental collision zones. Whether these iron-rich minerals originate from dry oxidation, dehydrogenation-oxidation or exsolution from a precursor wadsleyite phase is debatable. This paper explores high-pressure and high-temperature experiments in a hydrous harzburgite system, by taking advantage of electron backscattered diffraction (EBSD) analyses, to examine the formation of hematite in olivine. Experimental results show that hematite can be formed within olivine grains at pressures >6 GPa and temperatures in the 1073-1473 K range. EBSD analysis suggests that hematite rods (not associated with clinopyroxene) and host olivine have the following crystallographic relations: < 0001 rangle _{{Hem}} // [100]_{{Ol}} , < 10{-}10rangle _{{Hem}} //[001]_{{Ol}} , < 11{-}20rangle _{{Hem}} //[010]_{{Ol}} , which are consistent with those observed in natural garnet peridotite from the Dabie-Sulu ultra-high-pressure (UHP) metamorphic terrane. It is postulated that both hydroxide (OH-) and hydrogen (H+) ions have the potential to oxidize Fe2+ to Fe3+, followed by rapid dehydrogenation and slow Fe diffusion, thus forming hematite within the olivine grains. It is proposed that dehydrogenation-oxidation is the most likely formation mechanism of hematite inclusions within olivine, with the following two requirements: an ample amount of H2O and specific P- T conditions (>6 GPa, at 1073 K). Such conditions are consistent with those calculated in natural garnet peridotites from the Dabie-Sulu UHP metamorphic terranes. The present study also indicates that hematite (or magnetite?) inclusions in olivine contain important clues about the tectonic evolution of UHP rocks in continental crust collision zones.

  1. Experimental constraints on formation of hematite in olivine at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Zhang, Yanfei; Wang, Chao; Wu, Yao; Liu, Wenlong; Jin, Zhenmin

    2015-06-01

    Iron-rich oxides, such as magnetite or hematite, have been reported in olivine grains in many orogenic garnet peridotites from continental collision zones. Whether these iron-rich minerals originate from dry oxidation, dehydrogenation-oxidation or exsolution from a precursor wadsleyite phase is debatable. This paper explores high-pressure and high-temperature experiments in a hydrous harzburgite system, by taking advantage of electron backscattered diffraction (EBSD) analyses, to examine the formation of hematite in olivine. Experimental results show that hematite can be formed within olivine grains at pressures >6 GPa and temperatures in the 1073-1473 K range. EBSD analysis suggests that hematite rods (not associated with clinopyroxene) and host olivine have the following crystallographic relations: < 0001 rangle _{{Hem}} // [100]_{{Ol}} , < 10{-}10rangle _{{Hem}} //[001]_{{Ol}} , < 11{-}20rangle _{{Hem}} //[010]_{{Ol}} , which are consistent with those observed in natural garnet peridotite from the Dabie-Sulu ultra-high-pressure (UHP) metamorphic terrane. It is postulated that both hydroxide (OH-) and hydrogen (H+) ions have the potential to oxidize Fe2+ to Fe3+, followed by rapid dehydrogenation and slow Fe diffusion, thus forming hematite within the olivine grains. It is proposed that dehydrogenation-oxidation is the most likely formation mechanism of hematite inclusions within olivine, with the following two requirements: an ample amount of H2O and specific P-T conditions (>6 GPa, at 1073 K). Such conditions are consistent with those calculated in natural garnet peridotites from the Dabie-Sulu UHP metamorphic terranes. The present study also indicates that hematite (or magnetite?) inclusions in olivine contain important clues about the tectonic evolution of UHP rocks in continental crust collision zones.

  2. Calculations of Li Ion Diffusion in Olivine Phosphates

    SciTech Connect

    Dathar, Gopi Krishna Phani; Sheppard, Daniel; Stevenson, Keith J.; Henkelman, Graeme

    2011-09-13

    Kinetic pathways of Li-ion diffusion in olivine phosphates are calculated from density functional theory (DFT). Previously reported theoretical diffusion rates for Li ions and vacancies in defect-free crystalline FePO? and LiFePO? are six orders of magnitude faster than experimentally measured values. This discrepancy can be resolved by considering the different components of Li kinetics, including diffusion in the bulk, on the surface, in the presence of defects, and in varying local environments. Using DFT+U, we quantify each of these effects and determine that, while bulk diffusion is affected by strain and Li concentration, these are not significant enough to explain the slow diffusion observed in experiment. However, surface diffusion is observed to have have high barriers, which could contribute to slow kinetics in nanostructured cathodes. Anti-site defects also provide a possible explanation for slow diffusion, but only for vacancy diffusion in LiFePO?, which has a barrier of 0.71 eV, compared to 0.29 eV in defect-free channels. In FePO?, a concerted Li-ion diffusion mechanism around the anti-site defect is found to have a low barrier of 0.35 eV, allowing for facile cross-channel diffusion at room temperature. The difference between Li-ion and vacancy diffusion is understood in terms of a favorable coordination between Li ions and localized electrons on Fe centers at the transition states for Li-ion hopping in FePO?. Greater distances between vacancies and holes at the transition states for vacancy diffusion lead to higher diffusion barriers.

  3. Space Weathering in Olivine and the Mineralogy of (Some) M-Class Asteroids

    NASA Astrophysics Data System (ADS)

    Britt, Daniel; Kohout, Tomas; Schelling, Patrick; Consolmagno, Guy J.

    2014-11-01

    One aspect of space weathering of airless bodies is the production of nanophase iron (npFe0) from Fe bearing silicate minerals. The combined effects of low oxygen fugacity and solar-wind implanted H tend to result in strongly-reduced surfaces that can be chemically activated by heating due to micrometeorite impacts. The mineral kinetics of olivine makes it particularly vulnerable to reduction, decomposition, and npFe0 production. Kohout et al. has recently developed a new method of controlled npFe0 production on olivine powder grains that mimics the essential features of this weathering process and was developed to quantitatively evaluate spectral changes related to space weathering and presence of npFe0. Compared to fresh olivine the treated samples exhibit spectral characteristics of space weathering including spectral darkening, shallowing and attenuation of 1 µm olivine absorption band, and reddening. The attenuation of the 1 µm band significantly shrinks the band FWHM and shifts the much reduced band center to shorter wavelengths around 0.95 µm. These spectral changes are related to increasing amounts of npFe0 and the disruption of the crystal structure of the parent olivine. Significantly, the darkened, reddened, and band attenuated olivine spectra are a close match to a number of M-class asteroids. What is particularly interesting is the match with the weak absorption band near 0.95 µm seen in many M-class asteroids (i.e. 16 Psyche, 22 Kalliope, 55 Pandora to name a few). One of the major issues in asteroid science is the relative scarcity of olivine asteroids (the ”Great Dunite Shortage” coined by Bell et al in Asteroids II). One possibility worth further study is that asteroidal olivine may be hidden by the relative ease with which it weathers. The surface chemical and micrometeorite environment in the asteroid belt may produce over time a spectrum for an olivine-rich surface that is remarkably similar to that of an M-class asteroid.

  4. Replacement of olivine by serpentine in the carbonaceous chondrite Nogoya (CM2)

    NASA Astrophysics Data System (ADS)

    Velbel, Michael A.; Tonui, Eric K.; Zolensky, Michael E.

    2012-06-01

    Coarse (chondrule and isolated) olivine in some CM chondrites is replaced by serpentine in both centripetal and meshwork replacement textures. Locally preserved textures formed by partial replacement of coarse olivine by serpentine in the carbonaceous chondrite Nogoya (CM2) establish unique associations between each individual mass of serpentine and the specific olivine from which that serpentine formed. Electron probe microanalyses show that the composition of serpentine replacing coarse olivine is uniform throughout all analyzed volumes of Nogoya, and is independent of the composition of the olivine being replaced. If, as previously proposed, late-stage alteration fluids were Mg-rich because Fe-source minerals were depleted in earlier stages, then the uniform Mg-rich composition of the serpentine replacing large silicate grains during advanced stages of alteration may indicate diffusional homogenization of the aqueous solutions over progressively larger spatial scales, enabled by long timescales and previously proposed stagnant or slow-moving fluids. The range of olivine compositions replaced in Nogoya is even larger than previously reported from ALH 81002 (CM2). This militates against hypotheses of strong primary-mineral control on the compositions of alteration products, at least at advanced stages of alteration. The serpentine formed by olivine replacement in Nogoya is more magnesian than the counterpart serpentine replacing all anhydrous primary silicates in ALH 81002. This intermeteorite heterogeneity of replacement-serpentine composition between ALH 81002 and Nogoya indicates that the aqueous solutions in which the olivine-serpentine replacement reactions occurred were of different compositions in the two different CM parent-body volumes sampled by ALH 81002 and Nogoya. The more magnesian character of serpentines in Nogoya than in ALH 81002 indicates that the Nogoya aqueous-alteration environment was even more highly evolved toward Mg-rich solutions than the environment indicated by the composition of the serpentine in ALH 81002. Persistence of primary-silicate remnants within centripetal and meshwork serpentine indicates that either the aqueous alteration episodes in the parent-body volumes represented by individual meteorites were too short to allow complete replacement of olivine by serpentine, or one or more reactants (most likely water) were completely consumed before the coarse primary silicate was completely replaced. Seemingly incompatible arguments for and against primary-mineral control of serpentine composition during CM chondrite alteration may be reconciled by considering the different grain sizes and reaction timescales that likely existed in different textural settings.

  5. Space weathering simulations through controlled growth of iron nanoparticles on olivine

    NASA Astrophysics Data System (ADS)

    Kohout, Tomáš; ?uda, Jan; Filip, Jan; Britt, Daniel; Bradley, Todd; Tu?ek, Ji?í; Skála, Roman; Kletetschka, Gunther; Kašlík, Josef; Malina, Ond?ej; Šišková, Karolína; Zbo?il, Radek

    2014-07-01

    Airless planetary bodies are directly exposed to space weathering. The main spectral effects of space weathering are darkening, reduction in intensity of silicate mineral absorption bands, and an increase in the spectral slope towards longer wavelengths (reddening). Production of nanophase metallic iron (npFe0) during space weathering plays major role in these spectral changes. A laboratory procedure for the controlled production of npFe0 in silicate mineral powders has been developed. The method is based on a two-step thermal treatment of low-iron olivine, first in ambient air and then in hydrogen atmosphere. Through this process, a series of olivine powder samples was prepared with varying amounts of npFe0 in the 7-20 nm size range. A logarithmic trend is observed between amount of npFe0 and darkening, reduction of 1 ?m olivine absorption band, reddening, and 1 ?m band width. Olivine with a population of physically larger npFe0 particles follows spectral trends similar to other samples, except for the reddening trend. This is interpreted as the larger, ?40-50 nm sized, npFe0 particles do not contribute to the spectral slope change as efficiently as the smaller npFe0 fraction. A linear trend is observed between the amount of npFe0 and 1 ?m band center position, most likely caused by Fe2+ disassociation from olivine structure into npFe0 particles.

  6. Space weathering simulations through controlled growth of iron nanoparticles on olivine

    NASA Astrophysics Data System (ADS)

    Kohout, T.; ?uda, J.; Filip, J.; Britt, D.; Bradley, T.; Tu?ek, J.; Skála, R.; Kletetschka, G.; Kašlík, J.; Malina, O.; Šišková, K.; Zbo?il, R.

    2014-07-01

    Airless planetary bodies are directly exposed to space weathering. The main spectral effects of space weathering are darkening, reduction in intensity of silicate mineral absorption bands, and an increase in the spectral slope towards longer wavelengths (reddening). Production of nanophase metallic iron (npFe^{0}) during space weathering plays a major role in these spectral changes. A laboratory procedure for the controlled production of npFe^{0} in silicate mineral powders has been developed. The method is based on a two-step thermal treatment of low-iron olivine, first in ambient air and then in a hydrogen atmosphere. Through this process, a series of olivine powder samples was prepared with varying amounts of npFe^{0} in the 7-20-nm size range. A logarithmic trend is observed between the amount of npFe^{0} and darkening, reduction of 1-? m olivine absorption band, reddening, and the 1-? m band width. Olivine with a population of physically larger npFe^{0} particles follows spectral trends similar to other samples, except for the reddening trend. This is interpreted as follows: the larger, ˜40-50-nm sized npFe^{0} particles do not contribute to the spectral slope change as efficiently as the smaller npFe^{0} fraction. A linear trend is observed between the amount of npFe^{0} and the 1-? m band center position, most likely caused by the Fe^{2+} disassociation from the olivine structure into npFe^{0} particles.

  7. Olivine in terminal particles of Stardust aerogel tracks and analogous grains in chondrite matrix

    NASA Astrophysics Data System (ADS)

    Frank, David R.; Zolensky, Michael E.; Le, Loan

    2014-10-01

    The dearth of both major and minor element analyses of anhydrous silicate phases in chondrite matrix has thus far hindered their comparison to the Wild 2 samples. We present 68 analyses of olivine (Fa0-97) in the coarse-grained terminal particles of Stardust aerogel tracks and a comprehensive dataset (>103 analyses) of analogous olivine grains (5-30 ?m) isolated in CI, CM, CR, CH, CO, CV3-oxidized, CV3-reduced, C3-ungrouped (Acfer 094 and Ningqiang), L/LL 3.0-4, EH3, and Kakangari chondrite matrix. These compositions reveal that Wild 2 likely accreted a diverse assortment of material that was radially transported from various carbonaceous and ordinary chondrite-forming regions. The Wild 2 olivine includes amoeboid olivine aggregates (AOAs), refractory forsterite, type I and type II chondrule fragments and/or microchondrules, and rare relict grain compositions. In addition, we have identified one terminal particle that has no known compositional analog in the meteorite record and may be a signature of low-temperature, aqueous processing in the Kuiper Belt. The generally low Cr content of FeO-rich olivine in the Stardust samples indicates that they underwent mild thermal metamorphism, akin to a petrologic grade of 3.05-3.15.

  8. Olivine to spinel transformation in Mg2SiO4 via faulted structures

    NASA Astrophysics Data System (ADS)

    Boland, J. N.; Liu, L.-G.

    1983-05-01

    The olivine-to-spinel (alpha-to-gamma) transformation in forsterite (Mg2SiO4) was studied by transmission electron microscopy. Synthetic olivine was compressed in a diamond-anvil cell to about 220 kbar, laser heated to 1000 C, and air quenched; pressure was released over 30 min, and the ion-thinned central 50-micron region was examined in an electron microscope. The presence of residual olivine (less than one percent) was confirmed by X-ray powder diffraction. Olivine and spinel were found to be intercalated, a transformational growth pattern consistent with a martensitic transformation, and this explanation of the phenomena is supported by the orientation relationship of the two phases and the high density of stacking faults and dislocations in the residual olivine grains. The transformation mechanism for Mg2SiO4 is thus seen as similar to that proposed for Fe2SiO4 and different from that in Mg2GeO4 and Ni2SiO4.

  9. Atomic-scale simulation of space weathering in olivine and orthopyroxene

    NASA Astrophysics Data System (ADS)

    Quadery, Abrar H.; Pacheco, Shaun; Au, Alan; Rizzacasa, Natalie; Nichols, Joshua; Le, Timothy; Glasscock, Cameron; Schelling, Patrick K.

    2015-04-01

    Classical molecular dynamics was used to study the annealing of anion and cation Frenkel defects in olivine and orthopyroxene minerals. While it was found that for both minerals, reorganization of the Si-O bonds, often accompanied by large Si displacements, occurs to maintain the fourfold coordination of the SiO4 tetrahedra, important differences are observed in their annealing behavior. Specifically, cation defects are substantially more mobile in olivine than in orthopyroxene leading to rapid annihilation of cation Frenkel defects and formation of extended defects in olivine. By contrast, the diffusion rate of anion defects in orthopyroxene is much higher than that in olivine and also exhibits large anisotropy. Consequently, it was found that diffusion in orthopyroxene occurs without significant annihilation of anion Frenkel defects or trapping of anion interstitials or vacancies into clusters. The results obtained here are discussed in the context of space weathering of olivine and orthopyroxene. Specifically, two important observations are made which may explain previous experimental results. First, ion irradiation experiments that show reduced tolerance for radiation damage in orthopyroxene may be explained by the rapid, one-dimensional anion mobility which prevents healing of the lattice. Second, laser heating experiments which show that orthopyroxene has enhanced tolerance to reduction and the evolution of nanophase Fe inclusions could be due to the observed rapid anion diffusion in orthopyroxene, which might allow the bulk to act as a reservoir for the surface.

  10. Olivine + halides: a recipe for iron mobilization in volcanic ash?

    NASA Astrophysics Data System (ADS)

    Hoshyaripour, G.; Hort, M. K.; Langmann, B.

    2013-12-01

    During the last decade, scientific evidences strongly suggest that volcanic ash iron has fertilization impact upon the surface ocean. Still, it is not well constrained how the insoluble iron in ash (i.e., as a component in minerals and also glass) could be mobilized during volcanic eruptions and atmospheric transport. Here we investigate the volcanic plume controls on ash iron solubility. We develope a conceptual box model to simulate the high, mid and low temperature chemical, physical and thermodynamic processes in eruption plumes to better constrain the iron mobilization in volcanic ash. We take into account the interaction of different species in a solid-liquid-gas system representing various volcanic settings (convergent plate, divergent plate and hot spot). Results show that the hot core of a volcanic plume (T>600°C) does not produce soluble iron directly but significantly controls the Fe mineralogy and oxidation state at the ash surface. The final iron mineralogy at the ash surface (i.e. the ash's oxidation front with 1-100 nm thickness) is likely to be independent of temperature and oxygen fugacity and is closely correlated to the ratio of H2 and H2S content of the magmatic gas to the amount of entrained oxygen. As the plume continues rising and cooling, sulfuric acid condenses at about 150°C followed by water condensation at about 50°C which also dissociates sulfuric acid and produces H+ ions in the liquid phase. The aqueous phase scavenges the surrounding gas species (e.g. SO2, HCl, HF) and concurrently dissolves the ash surface constituents. Since HCl is about 4 orders of magnitudes more soluble than SO2, its dissolution mainly controls the pH of the liquid. Hence, high HCl concentrations in the gas phase results in lower pH in the aqueous phase (pH<0.5) and consequently an increase in the ash dissolution rate. Moreover reduced iron carrying minerals (e.g. fayalite) show a much higher dissolution rate in comparison with oxidized species (e.g. hematite). Thus, the presence of the reduced iron species in the mineral assemblage seems to be more favorable for the soluble iron production. We conclude that bio-available iron production is weakly correlated with the tectonic setting and is instead controlled by the halide content of the eruption plume and the oxidation state of the iron at the ash mineral assemblage (e.g. presence of olivine). This hypothesis could satisfactorily explain the extraordinary iron release from the ash of Hekla eruption in 2000 and also the fertilization impact caused by the ash erupted from Kasatochi in 2008.

  11. Unusual olivine and pyroxene composition in interplanetary dust and unequilibrated ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Klock, W.; Mckay, D. S.; Thomas, K. L.; Palme, H.

    1989-01-01

    The presence, in both a number of interplanetary dust particles (IDPs) and in meteorite matrices, of olivine and orthopyroxene grains, low in FeO but containing up to 5 wt pct MnO, is reported. The majority of olivines and pyroxenes in meteorites contain less than 0.5 wt pct MnO. The presence of these low-iron, manganese-enriched (LIME) olivines and pyroxenes in IDPs and meteorites may indicate a link between the origin and history of IDPs and the matrix material of primitive meteorites. The origin of the LIME silicates could be explained by condensation from a gas of solar composition. Forsterite is the first major silicate phase to condense from a solar nebula gas, and Mn, which is not stable as a metal under solar nebula conditions, would condense at about 1100 K as Mn2SiO4 in solid solution with forsterite.

  12. Chemical zoning and diffusion of Ca, Al, Mn, and Cr in olivine of springwater pallasite

    NASA Technical Reports Server (NTRS)

    Zhou, Y.; Steele, Ian M.

    1993-01-01

    The pallasites, consisting mainly of Fe-Ni metal and olivine, are thought to represent the interior of a planetary body which slowly cooled from high temperature. Although the olivines are nearly homogeneous, ion microprobe studies revealed variations of Ca, Ti, Co, Cr, and Ni near grain edges. These variations were thought to represent diffusion in response to falling temperature of the parent body. Pallasite cooling rates have been estimated based on kamacite taenite textures but results differ by x100. In principle elemental profiles in olivine can allow estimates of cooling rate if diffusion coefficients are known; in addition, given a cooling rate, diffusion coefficients could be derived. Data are presented which show that apparent diffusion profiles can be measured for Al, Ca, Cr, and Mn which qualitatively agree with expected diffusion rates and have the potential of providing independent estimates of pallasite cooling rates.

  13. Modeling the creep properties of olivine by 2.5-dimensional dislocation dynamics simulations

    NASA Astrophysics Data System (ADS)

    Boioli, Francesca; Carrez, Philippe; Cordier, Patrick; Devincre, Benoit; Marquille, Matthieu

    2015-07-01

    In this work we performed 2.5-dimensional (2.5D) dislocation dynamics simulations coupling climb with the glide dislocation motion to model the creep behavior of olivine, one of the main component of the Earth's upper mantle. In particular, we present an application of this method to determine the creep strain rate in a material with high lattice resistance, such as olivine. We show that by including the climb mechanism we reach steady state creep conditions. Moreover, we find that a creep power law with a stress exponent close to 3 can be extracted from our simulations and we provide a model based on Orowan's law to predict the creep strain rates in the high temperature and low stress regime. The model presented is relevant to describe the plastic flow of olivine in the Earth's mantle deformation conditions and can be useful to derive the high temperature creep behavior of other materials.

  14. Geochemistry of Pallasite Olivines and the Origin of Main-Group Pallasites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Rumble, D., III

    2006-01-01

    Main-group pallasites (PMG) are mixtures of iron-nickel metal and magnesian olivine thought to have been formed at the core-mantle boundary of an asteroid [1]. Some have anomalous metal compositions (PMG-am) and a few have atypically ferroan olivines (PMG-as) [2]. PMG metal is consistent with an origin as a late fractionate of the IIIAB iron core [2]. Most PMG olivines have very similar Fe/Mg ratios, likely due to subsolidus redox reaction with the metal [3]. In contrast, minor and trace elements show substantial variation, which may be explained by either: (i) PMG were formed at a range of depths in the parent asteroid; the element variations reflect variations in igneous evolution with depth, (ii) the pallasite parent asteroid was chemically heterogeneous; the heterogeneity partially survived igneous processing, or (iii) PMG represent the core-mantle boundaries of several distinct parent asteroids [4, 5]. We have continued doing major, minor and trace elements by EMPA and INAA on a wider suite of PMG olivines, and have begun doing precise oxygen isotope analyses to test these hypotheses. Manganese is homologous with Fe(2+), and can be used to distinguish between magmatic and redox processes as causes for Fe/Mg variations. PMG olivines have a range in molar 1000*Mn/Mg of 2.3-4.6 indicating substantial igneous fractionation in olivines with very similar Fe/Mg (0.138-0.148). The Mg-Mn-Fe distributions can be explained by a fractional crystallization-reduction model; higher Mn/Mg ratios reflect more evolved olivines while Fe/Mg is buffered by redox reactions with the metal. There is a positive association between Mn/Mg and Sc content that is consistent with igneous fractionation. However, most PMG olivines fall within a narrow Mn/Mg range (3.0-3.6), but these show a substantial range in Sc (1.00-2.29 micro-g/g). Assuming fractional crystallization, this Sc range could have resulted from approx.65% crystallization of an ultramafic magma. This is inconsistent with formation at the core-mantle boundary of a single asteroid [4]. One alternative is that the PMG are fragments of several asteroids, and these could have had different initial Sc contents, Mn/Mg and differences in igneous history. Our preliminary O isotope data and those of [6, 7] do not support this, although the coverage of PMG olivines is incomplete. The PMG-as Springwater is not easily fit in any scenario. Its olivine has among the highest Mn/Mg suggesting it is one of the most evolved, but the lowest Sc content suggesting it is the least evolved. The O isotopic composition of Springwater olivine is the same as that of other PMG. Thus there is no indication that it represents a distinct parent asteroid. Our preliminary O isotopic data favor a single PMG parent asteroid. In this case, the olivines are more likely melt-residues, and that the parent asteroid was initially heterogeneous in chemical, but not isotopic, composition.

  15. The influence of bulk composition and dynamic melting conditions on olivine chondrule textures

    NASA Technical Reports Server (NTRS)

    Connolly, Harold C., Jr.; Hewins, Roger H.

    1991-01-01

    The effects of the bulk composition and the dynamic melting conditions on the texture of olivine chondrules were investigated in a series of heating experiments. It is shown that variations in the olivine chondrule textures can be produced by varying the FeO/(FeO + MgO) ratio between the average Type IA and Type II chondrule compositions, could affect the texture of a chondrule at a constant initial melting temperature and heating time. A range of the heating times and the masses of precursor spheres caused variations in the degree of melting and in chondrule textures. Chondrule textures were distributed on a graph of initial temperatures vs. FeO/(FeO + MgO) ratios as bands parallel to the olivine disappearance curve. This graph could be used to predict chondrule textures from Fe/(FeO + MgO) ratios at specific initial melting temperatures.

  16. Thermal histories of CO3 chondrites - Application of olivine diffusion modelling to parent body metamorphism

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.; Rubie, David C.

    1991-01-01

    The petrologic sequence observed in the CO3 chondrite group has been suggested to be the result of thermal metamorphism on a parent body. A model developed to examine the possibility that chondrule and matrix olivines equilibrated in situ, during parent body metamorphism is presented. The model considers Fe-Mg interdiffusion between chondrule and matrix olivines. Zoning profiles comparable to those observed in chondrule olivines from partially equilibrated members of the series are reproduced successfully. Metamorphism of CO3 chondrites on a parent body is therefore a viable model for the observed equilibration. Results indicate that peak metamorphic temperatures experienced by the CO3 chondrites were around 500 C, and that the range of peak temperatures between unequilibrated and equilibrated subtypes was relatively narrow, around 100 C.

  17. Diffusive modification of primary zoning in olivine cores in Angrite LEW 87051. [Abstract only

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Mckay, G.; Miyamoto, M.; Takeda, H.

    1994-01-01

    Angrite LEW 87051 consists of large olivine crystals set in a fine-grained groundmass that clearly represents a crystallized melt. A few olivines contain Ca-poor, Cr-rich cores that crystallized from a very different melt than the outer part of the crystals constituting the majority of olivine in LEW 87051. We evaluate a model in which the cores formed through fractional crystallization of one melt, then were incorporated into a different melt as xenocrysts, whereupon the original zoning patterns were modified by diffusion. Using a similar approach, we calculate zoning patterns for the cores that would result from perfect fractional crystallization, compare them with the observed zoning, and determine whether the differences could result from diffusive modification consistent with known diffusion rates for Ca, Mn, and Cr. Using distribution coefficients from the 1400 C, IW + 1 experiments, we computed CaO, Cr2O3, and MnO abundances in the hypothetical parent melt by inverting the olivine at the centers of the cores. We further assumed that the primary zoning profile for CaO is essentially unmodified, because the diffusion rate of Ca in olivine is slow. We carried out the fractional crystallization calculation until the calculated Ca content was that observed at break in zoning profiles at the outer edge of the core. We then normalized the distance of this calculated profile to the length of the observed profile in the olivine core and calculated profiles for MnO and Cr2O3. The CaO zoning profile agrees well with the observed profile. The observed MnO profile is slightly higher than the calculated profile near the edge. Diffusion calculations indicate that reversal of the general trend of primary zoning through diffusion would require that diffusion of Cr is 5-10x faster than that of Mn.

  18. Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt.

    PubMed

    de Vries, B L; Acke, B; Blommaert, J A D L; Waelkens, C; Waters, L B F M; Vandenbussche, B; Min, M; Olofsson, G; Dominik, C; Decin, L; Barlow, M J; Brandeker, A; Di Francesco, J; Glauser, A M; Greaves, J; Harvey, P M; Holland, W S; Ivison, R J; Liseau, R; Pantin, E E; Pilbratt, G L; Royer, P; Sibthorpe, B

    2012-10-01

    Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets. Collisions between such bodies produce small dust particles, the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg(2-2x)Fe(2x)SiO(4)) has been done for the protoplanetary disk HD?100546 (refs 3, 4) and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids (x???0.29). In the cold outskirts of the ??Pictoris system, an analogue to the young Solar System, olivine crystals were detected but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets. Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of ??Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15-45 astronomical units from the star (one astronomical unit is the Sun-Earth distance), determine their magnesium-rich composition (x = 0.01?±?0.001) and show that they make up 3.6?±?1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System, even though ??Pictoris is more massive and more luminous and has a different planetary system architecture. PMID:23038467

  19. Rheological contrast between olivine and garnet at high pressures under anhydrous conditions

    NASA Astrophysics Data System (ADS)

    Mei, S.; Suzuki, A. M.; Kohlstedt, D. L.; Durham, W. B.; Dixon, N. A.

    2010-12-01

    In this study, we carried out experiments investigating the rheological contrast between olivine and garnet, two major components of the mantle, at mantle temperatures and pressures. Experiments were carried out using a deformation-DIA at the National Synchrotron Light Source at Brookhaven National Laboratory. Samples were fabricated from powdered minerals; olivine was from San Carlos and garnet from the Dabie-Sulu orogenic belt in China. In the experiments, a cold-pressed cylinder of fine-grained olivine and one of garnet, each with a diameter of ~1.1 mm and a length of ~0.8 mm, were stacked together, separated by a nickel foil disk. This duplex sample was assembled with alumina pistons, a boron nitride sleeve, and graphite resistance heater into a 6.2-mm edge length cubic mullite-pyrophyllite pressure cell. Experiments were carried out at 1373 - 1573 K and pressures of 3 - 5 GPa. With the synchrotron x-ray beam, a time series of in-situ radiographs enables monitoring of the instantaneous lengths of both deforming samples at the same temperature, pressure, and load. At our experimental conditions, both samples deform with stress exponents of n ? 3 and with activation energies of Q ? 300 kJ/mol. Samples of olivine deform only a factor of ~1.5 faster than samples of garnet of similar grain size, indicating that there is no significant rheological contrast between samples of olivine and garnet under anhydrous conditions. This result, which is the first direct comparison of the rheological behavior of olivine and garnet, provides a solid basis for modeling the rheological structures of subducted lithosphere.

  20. XANES Measurements of Cr Valence in Olivine and their Applications to Planetary Basalts (Invited)

    NASA Astrophysics Data System (ADS)

    Bell, A. S.; Burger, P.; Le, L.; Shearer, C. K.; Papike, J.; Sutton, S. R.; Newville, M.; Jones, J. H.

    2013-12-01

    The oxidation state and partitioning behavior of trace Cr in terrestrial and planetary basaltic magmas has long been a subject of petrologic inquiry. We have performed a series of experiments designed to examine the relationship between oxygen fugacity and the ratio of divalent to trivalent Cr present in olivine crystals grown from a basaltic liquid. The experimental olivine crystals were grown at fO2 values ranging from IW-1 to IW+3.4. The melt composition used in this work was modeled after the bulk composition of the primitive, basaltic martian meteorite Yamato 980459 (Y-98). Chromium valence in the olivine crystals was measured with X-ray-Absorption-Near-Edge-Spectroscopy (XANES) at the Advanced Photon Source, Argonne National Laboratory. Chromium K-edge XANES data were acquired with the x-ray microprobe of GSECARS beamline 13-ID-E. Beam focusing was accomplished with dynamically-figured Kirkpatrick-Baez focusing mirrors; this configuration yielded a beam focused to a final spot size of ~ 4 ?m2. Results from the XANES measurements indicate that the ratio of divalent to trivalent Cr in the olivine is systematically correlated with fO2 in a manner that is consistent with the expected redox systematics for Cr2+- Cr3+ in the melt. In this way, measurements of the Cr2+/Cr3+ in olivine phenocrysts can indirectly reveal information about the Cr valence ratio and fO2 the liquid from which it grew even in the absence of a quenched melt phase. Although the results from the experiments presented in this work specifically apply to the Yamato 98 parental liquid, the concepts and XANES analytical techniques used in this study present a novel, generalized methodology that may be applicable to any olivine-bearing basalt. Furthermore, the XANES based measurements are made on a micron-scale, thus potential changes of the Cr2+/Cr3+ in the melt occurring during crystallization may be recorded in detail.

  1. Reaction-induced fracturing during olivine serpentinization: A mechanistic investigation at the interface scale

    NASA Astrophysics Data System (ADS)

    Plümper, O.; Røyne, A.; Malthe-Sørenssen, A.; King, H. E.; Jamtveit, B.

    2012-04-01

    Serpentinization of the Earth's impermeable upper mantle is one of the most fundamental metamorphic hydration reactions. It governs lithospheric weakening, geochemical subduction zone input and possibly even the formation of life-essential building blocks. Serpentinization relies on fluid pathway generation due to low initial permeability and the large positive solid volume change associated with hydration. Although these pathways can be produced as a tectonic stress response, there is substantial evidence that the volume increase during olivine serpentinization itself generates stresses sufficient to fracture the rock. Nonetheless, the actual fracturing mechanism during olivine serpentinization is largely unexplored. Unconstrained batch experiments (Okamoto et al. 2011, this study) produce comparable hierachial fracture patterns to those found in natural samples demonstrating that no external forces (e.g., tensile stress) are required for fracturing to take place. Combining this with the observation that fluid-mediated mineral replacement advances via an interface-coupled dissolution-reprecipitation mechanism (e.g., Putnis 2009) without solid-state diffusion into the dissolving mineral indicates that classical (stress) corrosion cracking mechanisms cannot describe fracturing during olivine serpentinization. By uniting micro- and nanostructural characteristics ubiquitous to serpentinized olivine grains with a coupled diffusion-reaction-deformation model and crack growth theory this study explores the sub-critical fracturing mechanism at the interfacial scale. We present a new multistep reaction process and test the feasibility of a molecular wedge-assisted fracturing mechanism based on the following ubiquitously identified features: (1) no rotation of grain domains during fragmentation, (2) isotropic fracture orientation distribution with a uniform average width of individual finite length serpentine veins, (3) cumulative fragment area distribution with a log-normal scaling behavior following a hierachical fracturing model, (4) etch pit development at olivine-lizardite reaction interfaces, (5) crack initiation at these surface perturbations and (6) amorphous layer formation during olivine dissolution prior to serpentine nucleation (e.g., Rumori et al. 2004). Based on these observations we propose an entirely self-propagating reaction-driven fracturing process, where fractures nucleate at dissolution-induced surface perturbations assisted by a molecular wedge of amorphous 'gel', followed by further olivine dissolution and serpentine (±brucite) reprecipitation coupled with the force of crystallization. This process results in the observed hierarchical fracture network. Our results suggest that the mechanical force needed to advance serpentinization at the grain-scale does not rely on external forces but is due to interface-coupled, chemomechanical feedback during olivine re-equilibration in the presence of a fluid phase. Nevertheless, the influence of tectonic forces will need to be accounted for at larger scales.

  2. Acoustic emissions produced by anticrack faulting during the olivine-spinel transformation

    NASA Astrophysics Data System (ADS)

    Green, H. W., II; Scholz, C. H.; Tingle, T. N.; Young, T. E.; Koczynski, T. A.

    1992-04-01

    Anticrack faulting during the phase transformations of olivine to its denser polymorphs is a principal contender for the mechanism of deep-focus earthquakes. The original work on Mg2GeO4 established that initiation of faulting by this mechanism is not due to brittle fracture, and subsequent experiments on olivine of mantle composition showed that it can operate at pressures of at least 14 GPa. Acoustic emissions accompanying anticrack faulting in Mg2GeO4 are reported, thereby confirming that this mechanism involves a dynamic instability accompanied by elastic radiation.

  3. First finding of burkeite in melt inclusions in olivine from sheared lherzolite xenoliths.

    PubMed

    Korsakov, Andrey V; Golovin, Alexander V; De Gussem, Kris; Sharygin, Igor S; Vandenabeele, Peter

    2009-08-01

    For the first time burkeite was observed as a daughter phase in the melt inclusions in olivine by Raman spectroscopy. The olivine comes from sheared lherzolite xenoliths from the Udachnaya-East kimberlite pipe (Yakutia, Russia). This anhydrous sulfate-carbonate mineral (Na(6)(CO(3))(SO(4))(2)) is generally considered to be a characteristic mineral in saline soils or in continental lacustrine evaporite deposits. Recently, however, this mineral was identified in hydrothermal fluids. Our observations indicate that burkeite can also be formed from a mantle-derived melt. PMID:19058996

  4. Short- and long-term olivine weathering in Svalbard: implications for Mars.

    PubMed

    Hausrath, E M; Treiman, A H; Vicenzi, E; Bish, D L; Blake, D; Sarrazin, P; Hoehler, T; Midtkandal, I; Steele, A; Brantley, S L

    2008-12-01

    Liquid water is essential to life as we know it on Earth; therefore, the search for water on Mars is a critical component of the search for life. Olivine, a mineral identified as present on Mars, has been proposed as an indicator of the duration and characteristics of water because it dissolves quickly, particularly under low-pH conditions. The duration of olivine persistence relative to glass under conditions of aqueous alteration reflects the pH and temperature of the reacting fluids. In this paper, we investigate the utility of 3 methodologies to detect silicate weathering in a Mars analog environment (Sverrefjell volcano, Svalbard). CheMin, a miniature X-ray diffraction instrument developed for flight on NASA's upcoming Mars Science Laboratory, was deployed on Svalbard and was successful in detecting olivine and weathering products. The persistence of olivine and glass in Svalbard rocks was also investigated via laboratory observations of weathered hand samples as well as an in situ burial experiment. Observations of hand samples are consistent with the inference that olivine persists longer than glass at near-zero temperatures in the presence of solutions at pH approximately 7-9 on Svalbard, whereas in hydrothermally altered zones, glass has persisted longer than olivine in the presence of fluids at similar pH at approximately 50 degrees C. Analysis of the surfaces of olivine and glass samples, which were buried on Sverrefjell for 1 year and then retrieved, documented only minor incipient weathering, though these results suggest the importance of biological impacts. The 3 types of observations (CheMin, laboratory observations of hand samples, burial experiments) of weathering of olivine and glass at Svalbard show promise for interpretation of weathering on Mars. Furthermore, the weathering relationships observed on Svalbard are consistent with laboratory-measured dissolution rates, which suggests that relative mineral dissolution rates in the laboratory, in concert with field observations, can be used to yield valuable information regarding the pH and temperature of reacting martian fluids. PMID:19191538

  5. The olivine-ilmenite thermometer. [partitioning effect of temperature on iron ions and magnesium

    NASA Technical Reports Server (NTRS)

    Andersen, D. J.; Lindsley, D. H.

    1979-01-01

    It is noted that the partitioning of Fe(2+) and Mg between olivine and ilmenite is temperature-dependent and can serve as a geothermometer if the activity-composition relations are determined. The paper reports on the study of the partitioning from 700-980 C at 1 kbar and 800-900 C at 13 kbar, and develops a solution model to account for the nonideality of olivine in the binary system fosterite-fayalite and for ilmenite in the ternary system ilmenite-geikielite-hematite. A comparison with crystallization experiments shows that this thermometer may be safely extrapolated to temperatures higher than those of the exchange experiments.

  6. Experimental shock metamorphism of mono- and polycrystalline olivine - A comparative study

    NASA Technical Reports Server (NTRS)

    Bauer, J. F.

    1979-01-01

    The paper reports on a series of controlled shock recovery experiments which have been performed on over 40 samples including monocrystalline, polycrystalline, dunite, and porous particulate olivine-bearing targets. Results of the mineralogical and petrological analyses of these samples are used to establish a general and comparative diagnosis of shock effects generated in various olivine-bearing materials. Finally, some experiments are conducted under different ambient pO2 conditions so that information on the distribution of observed impact features is derived as a function not only of peak pressure and texture of the target sample, but also of specific environmental conditions.

  7. Olivine Composition of the Mars Trojan 5261 Eureka: Spitzer IRS Data

    NASA Technical Reports Server (NTRS)

    Lim, L. F.; Burt, B. J.; Emery, J. P.; Mueller, M.; Rivkin, A. S.; Trilling, D.

    2011-01-01

    The largest Mars trojan, 5261 Eureka, is one of two prototype "Sa" asteroids in the Bus-Demeo taxonomy. Analysis of its visible/near-IR spectrum led to the conclusion that it might represent either an angritic analog or an olivine-rich composition such as an R chondrite. Spitzer IRS data (5-30 micrometers) have enabled us to resolve this ambiguity. The thermal-IR spectrum exhibits strong olivine reststrahlen features consistent with a composition of approximately equals Fo60-70. Laboratory spectra of R chondrites, brachinites, and chassignites are dominated by similar features.

  8. Ringwoodite Lamellae in Olivine from the S6 Chondrite Tenham: The Transformation Mechanism

    NASA Astrophysics Data System (ADS)

    Xie, Z.; Sharp, T. G.; Decarli, P. S.

    2006-12-01

    Ringwoodite lamellae in partially transformed olivine have been reported to occur in the shock-induced melt veins or near the melt veins in heavily shocked (S6) chondrites [1-4]. These features were interpreted to have formed by a coherent intracrystalline transformation mechanism like that observed in experimentally transformed samples by Kerschhofer et al. [5-7]. However, our SEM and TEM observations on the partially transformed olivine suggest that the transformation is incoherent and occurs along specific orientation [4], which is in agreement with the new interpretation of ringwoodite lamellae based on new SEM and SXRD observations [8]. Here we report more detailed TEM results, which are crucial to understand the transformation mechanism. Abundant ringwoodite lamellae were found in olivine grains, which occur as host-rock fragments entrained in melt veins and pockets. These partially transformed olivines are commonly intergrown with enstatite and plagioclase in multi-phase fragments. High-resolution SEM images reveal that the ringwoodite lamellae are not continuous, but rather polycrystalline ringwoodite with crystal size about 1 mm. Preliminary TEM results show that olivine are heavily deformed or occur as fine olivine grains, and ringwoodite lamellae consist of individual ringwoodite grains in the matrix of olivine fine grains. The discontinuous lamellar textures that we observe strongly suggest that the lamellae consist of many distinct ringwoodite crystallites rather than single-crystal lamella. It is possible that lamellae of polycrystalline ringwoodite in olivine could form by a mechanism analogous to the formation of planar deformation features (PDF), representing preferential transformation along specific crystallographic defect planes of the host phase. [1 Chen et al. (2004) Proceedings. of NAS 101(42), 15033-15037. [2] Ohtani et al. (2004) EPSL 227(3-4), 505- 515. [3] Beck, et al. (2005) Nature 435, 1071-1074. [4] Xie and Sharp (2006), LPSC XXXVII, 2306.pdf. [5] Kerschhofer et al. (1996) Science 274 (5284), 79-81. [6] Kerschhofer et al. (1998) Mineralogical magazine 62(5),617-638. [7] Kerschhofer et al. (2000) PEPI 121, 59-76. [8] Chen et al. (2006) Meteoritics Planet. Sci. (41), 731-737.

  9. A valid Margules formulation for an asymmetric ternary solution - Revision of the olivine-ilmenite thermometer, with applications

    NASA Technical Reports Server (NTRS)

    Andersen, D. J.; Lindsley, D. H.

    1981-01-01

    A derivation of a valid asymmetric ternary Margules expression for the excess free energy is presented, and the olivine-ilmenite thermometer is revised accordingly. Although the effect on the thermometer is relatively small, the revision results in improved precision. Estimated temperatures of equilibration are presented for olivine and ilmenite from lunar and terrestrial rocks.

  10. Stress, strain, and B-type olivine fabric in the fore-arc mantle: Sensitivity tests using

    E-print Network

    van Keken, Peter

    Stress, strain, and B-type olivine fabric in the fore-arc mantle: Sensitivity tests using high-arc mantle. The presence of B-type olivine fabric in the mantle wedge may provide an explanation that provide insights into the distribution and magnitude of B-type fabric using two-dimensional, high

  11. B-type olivine fabric in the mantle wedge: Insights from high-resolution non-Newtonian subduction zone models

    E-print Network

    van Keken, Peter

    B-type olivine fabric in the mantle wedge: Insights from high-resolution non-Newtonian subduction of subduction zones. These include 3-D flow effects, parallel melt filled cracks, and B-type olivine fabric. We predict the distribution of B- type and other fabrics with high-resolution thermal and stress models

  12. A new systematic approach using the Modified Gaussian Model: Insight for the characterization of chemical composition of olivines, pyroxenes and olivine-pyroxene mixtures

    NASA Astrophysics Data System (ADS)

    Clénet, Harold; Pinet, Patrick; Daydou, Yves; Heuripeau, Frédérick; Rosemberg, Christine; Baratoux, David; Chevrel, Serge

    2011-05-01

    An automatic procedure has been implemented on the original MGM approach ( Sunshine et al., 1990) in order to deal with an a priori unknown mafic mineralogy observed in the visible-near infrared by reflectance spectroscopy in the case of laboratory or natural rock spectra. We consider all the mixture possibilities involving orthopyroxene, clinopyroxene and olivine, and use accordingly for each configuration different numbers of Gaussians, depending on the potential complexity of the mixture. A key issue is to initialize the MGM procedure with a proper setting for the Gaussians parameters. An automatic analysis of the shape of the spectrum is first performed. The continuum is handled with a second order polynomial adjusted on the local maxima along the spectrum and Gaussians parameters initial settings are made on the basis of laboratory results available in the literature in the case of simple mixtures of mafic minerals. The returned MGM solutions are then assessed on spectroscopic grounds and either validated or discarded, on the basis of a mineralogical sorting. The results presented in this paper are a first quantitative step to characterize both modal and chemical compositions of pyroxenes and olivines. A demonstration of the methodology on specific examples of binary and ternary olivine-pyroxenes mixtures has been made, which shows that the different non-linear effects which affect the Gaussian parameters (center and strength) can be successfully handled. Of note is the fact that the band center positions associated with the different mafic minerals are not set here in the inverse problem, and thus the MGM outputs are truly informative of the chemical composition of pyroxenes and olivines. With the consideration of some limits on the detection thresholds, these results are quite promising for increasing the operational use of the Modified Gaussian Model with large hyperspectral data sets in view of establishing detailed mineralogical mappings of magmatic units.

  13. Reduced chromium in olivine grains from lunar basalt 15555 - X-ray Absorption Near Edge Structure (XANES)

    NASA Technical Reports Server (NTRS)

    Sutton, S. R.; Jones, K. W.; Gordon, B.; Rivers, M. L.; Bajt, S.; Smith, J. V.

    1993-01-01

    The oxidation state of Cr in 200-micron regions within individual lunar olivine and pyroxene grains from lunar basalt 15555 was inferred using X-ray Absorption Near Edge Structure (XANES). Reference materials had previously been studied by optical absorption spectroscopy and included Cr-bearing borosilicate glasses synthesized under controlled oxygen fugacity and Cr-doped olivines. The energy dependence of XANES spectral features defined by these reference materials indicated that Cr is predominantly divalent in the lunar olivine and trivalent in the pyroxene. These results, coupled with the apparent f(02)-independence of partitioning coefficients for Cr into olivine, imply that the source magma was dominated by divalent Cr at the time of olivine crystallization.

  14. Telling zoned from zoned: LA-MC-ICPMS and SIMS iron isotopic measurements of olivine

    NASA Astrophysics Data System (ADS)

    Sio, C.; Dauphas, N.; Teng, F.; Chaussidon, M.; Helz, R. L.; Roskosz, M.

    2012-12-01

    Previous studies have revealed that iron and magnesium isotopes may be used to distinguish diffusion-driven zoning from crystal growth zoning in olivine crystals [1-3]. In magmatic systems, Mg-rich olivine is an early crystallizing phase. As the melt evolves, it becomes more Fe-rich, so that in reaching equilibrium, Fe diffuses into and Mg diffuses out of the initial olivine crystal. Because light isotopes diffuse faster than heavy isotopes [4], such diffusion-driven mechanism is accompanied with 1) a negative correlation of Fe and Mg isotopes, and 2) a negative correlation of Fe isotopes and a positive correlation of Mg isotopes with Fo#. Teng et al. [1] showed these correlations in olivine fragments from Kilauea Iki lava lake. Sio et al. [3] used microdrilling techniques to spatially resolve the same correlations in an olivine phenocryst from the Kilauea Iki lava lake. LA-MC-ICPMS and SIMS were used to measure Fe isotopes in the same olivine phenocryst [5]. These techniques provide lateral and depth resolution approximately an order of magnitude higher than microdrilling. There is perfect agreement in iron isotopic measurements between these three techniques. The rim of the olivine is at -0.2 ‰ and the core is at -1.3 ‰ in ?56Fe relative to IRMM-014. The thermal history and petrography of the Kilauea Iki lava lake is known, so diffusion-controlled zoning in the olivine phenocryst may be modeled as in a laboratory experiment. After measuring the crystallographic orientation of the olivine with TEM in a FIB section, the average Mg-Fe interdiffusion coefficient is calculated as a fraction of DMg-Fe along the [001] axis. The derived DFe-Mg[001] appears to be 1.1 to 8.6 times higher than the parameterization given by [6]. The large range in DFe-Mg[001] results from slight uncertainties in the initial lake temperature and the geometry of the olivine phenocryst used in the modeling. The empirical ?, used to relate diffusivities of isotopes of the same element expressed in Dl/Dh = (mh/ml)^? where l stands for the light isotope, and h stands for the heavy isotope, is 0.22-0.29 for 54Fe and 56Fe, and 0.16-0.20 for 24Mg and 26Mg. These ?-values are significantly higher than those documented in magmas [4]. LA-MC-ICPMS and SIMS provide the means to measure iron isotopic compositions with high spatial resolution in olivines. Such techniques can be employed on zoned crystals to understand their crystallization and cooling histories. Our work establishes LA-MC-ICPMS and SIMS Fe isotopic analyses as a powerful tool of petrology in the study of zoned minerals. [1] Teng et al. (2011) EPSL 308, 317-324. [2] Dauphas et al. (2010) Geochim. Cosmochim. Acta 74, 3274-3291. [3] Sio et al. (2011) Goldschmidt Abstract 1884. [4] Richter et al. (2009) Geochim. Cosmochim. Acta 73, 4250-4263. [5] Sio et al. (2011) Goldschmidt Abstract 974. [6] Dohmen et al. (2007) Phys Chem Minerals 34, 597-598

  15. Space Weathering of Olivine in Lunar Soils: A Comparison to Itokawa Regolith Samples

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Berger, E. L.

    2014-01-01

    Regolith particles from airless bodies preserve a record of the space weathering processes that occurred during their surface exposure history. These processes have major implications for interpreting remote-sensing data from airless bodies. Solar wind irradiation effects occur in the rims of exposed grains, and impact processes result in the accumulation of vapordeposited elements and other surface-adhering materials. The grains returned from the surface of Itokawa by the Hayabusa mission allow the space weathering "style" of a chondritic, asteroidal "soil" to be compared to the lunar case. Here, we present new studies of space-weathered olivine grains from lunar soils, and compare these results to olivine grains from Itokawa. Samples and Methods: We analyzed microtome thin sections of olivine grains from the 20-45 micron fractions of three lunar soils: 71061, 71501 and 10084 (immature, submature and mature, respectively). Imaging and analytical data were obtained using a JEOL 2500SE 200kV field-emission scanning-transmission electron microscope equipped with a thin-window energy-dispersive x-ray spectrometer. Similar analyses were obtained from three Hayabusa olivine grains. Results and Discussion: We observed lunar grains showing a range of solar flare track densities (from <10(exp 9) to approx.10(exp 12)/sq cm). The lunar olivines all show disordered, highly strained, nanocrystalline rims up to 150-nm thick. The disordered rim thickness is positively correlated with solar flare track density. All of the disordered rims are overlain by a Si-rich amorphous layer, ranging up to 50-nm thick, enriched in elements that are not derived from the host olivine (e.g., Ca, Al, and Ti). The outmost layer represents impact-generated vapor deposits typically observed on other lunar soil grains. The Hayabusa olivine grains show track densities <10(exp 10)/sq cm and display disordered rims 50- to 100-nm thick. The track densities are intermediate to those observed in olivines in immature and submature lunar soils and indicate surface exposures of approx. 10(exp 5) years. The outermost few nanometers of the disordered rims on Hayabusa olivines are more Si-rich and Mg- and Fe-depleted relative to the cores of the grains and likely represent a minor accumulation of impact-generated vapors or sputter deposits. Nanophase Fe metal particles are less abundant in the Hayabusa rims compared to the rims on lunar grains. Conclusions: The Hayabusa and lunar olivine grain rims have widths and microstructures consistent with formation from atomic displacement damage from solar wind ions. The space weathering features in the Hayabusa grains are similar to those observed in olivines from immature to submature lunar soils. A major difference, however, is that the Hayabusa grains appear to lack the hypervelocity impact products (melt spherules, thick vapor deposits, and abundant nanophase Fe metal particles) that are common in lunar soil grains with a similar exposure history.

  16. Olivine Weathering and Sulfate Formation Under Cryogenic Conditions

    NASA Astrophysics Data System (ADS)

    Niles, P. B.; Golden, D. C.; Michalski, J. R.

    2013-12-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one of the most important discoveries being wide-spread layered sedimentary deposits associated with sulfate minerals across the low to mid latitude regions of Mars. The mechanism for sulfate formation on Mars has been frequently attributed to playa-like evaporative environments under prolonged warm conditions. An alternate view of the ancient martian climate contends that prolonged warm temperatures were never present and that the atmosphere and climate has been similar to modern conditions throughout most of its history. This view has had a difficult time explaining the sedimentary history of Mars and in particular the presence of sulfate minerals which seemingly need more water. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars. This study seeks to test whether sulfate formation may be possible at temperatures well below 0°C in water limited environments removing the need for prolonged warm periods to form sulfates on early Mars. To test this idea we performed laboratory experiments to simulate weathering of mafic minerals under Mars-like conditions. The weathering rates measured in this study suggest that fine grained olivine on Mars would weather into sulfate minerals in short time periods if they are exposed to H2SO4 aerosols at temperatures at or above -40°C. In this system, the strength of the acidic solution is maximized through eutectic freezing in an environment where the silicate minerals are extremely fine grained and have high surface areas. This provides an ideal environment despite the very low temperatures. On Mars the presence of large deposits of mixed ice and dust is undisputed. The presence of substantial sulfur-rich volcanism, and sulfur-rich surface deposits also makes it very likely that sul-fate aerosols have also been an important component of the martian atmosphere. Thus mixtures of ice, dust, and sulfate aerosols are likely to have been common on the martian surface. Given the fact that it is not difficult to achieve surface temperatures above -40°C on Mars throughout its history, it seems likely that sulfate formation on Mars is controlled by the availability of sulfate aerosols and not by the martian climate. The current polar regions of Mars and Earth provide interesting analogs. Large regions of sulfate-rich material have been detected on and around the modern north polar region of Mars. The prevalence of ice-dust mixtures in this region and the existence of sulfates within the ice cap itself are strong evidence for the origin of the sulfates from inside the ice deposits. In addition sulfates have been found in ice deposits in Greenland and Mount Fuji on Earth that have been attributed to forming within the ice deposit. These sulfates can form either through interaction with dust particles in the atmosphere or through weathering inside the ice itself.

  17. Olivine Weathering aud Sulfate Formation Under Cryogenic Conditions

    NASA Technical Reports Server (NTRS)

    Niles, Paul B.; Golden, D. C.; Michalski, J.

    2013-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one of the most important discoveries being wide-spread layered sedimentary deposits associated with sulfate minerals across the low to mid latitude regions of Mars. The mechanism for sulfate formation on Mars has been frequently attributed to playa-like evaporative environments under prolonged warm conditions. An alternate view of the ancient martian climate contends that prolonged warm temperatures were never present and that the atmosphere and climate has been similar to modern conditions throughout most of its history. This view has had a difficult time explaining the sedimentary history of Mars and in particular the presence of sulfate minerals which seemingly need more water. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars. This study seeks to test whether sulfate formation may be possible at temperatures well below 0degC in water limited environments removing the need for prolonged warm periods to form sulfates on early Mars. To test this idea we performed laboratory experiments to simulate weathering of mafic minerals under Mars-like conditions. The weathering rates measured in this study suggest that fine grained olivine on Mars would weather into sulfate minerals in short time periods if they are exposed to H2SO4 aerosols at temperatures at or above -40degC. In this system, the strength of the acidic solution is maximized through eutectic freezing in an environment where the silicate minerals are extremely fine grained and have high surface areas. This provides an ideal environment despite the very low temperatures. On Mars the presence of large deposits of mixed ice and dust is undisputed. The presence of substantial sulfur-rich volcanism, and sulfur-rich surface deposits also makes it very likely that sulfate aerosols have also been an important component of the martian atmosphere. Thus mixtures of ice, dust, and sulfate aerosols are likely to have been common on the martian surface. Given the fact that it is not difficult to achieve surface temperatures above -40degC on Mars throughout its history, it seems likely that sulfate formation on Mars is controlled by the availability of sulfate aerosols and not by the martian climate. The current polar regions of Mars and Earth provide interesting analogs. Large regions of sulfaterich material have been detected on and around the modern north polar region of Mars. The prevalence of ice-dust mixtures in this region and the existence of sulfates within the ice cap itself are strong evidence for the origin of the sulfates from inside the ice deposits. In addition sulfates have been found in ice deposits in Greenland and Mount Fuji on Earth that have been attributed to forming within the ice deposit. These sulfates can form either through interaction with dust particles in the atmosphere or through weathering inside the ice itself.

  18. The whole-block method and water diffusion in olivine

    NASA Astrophysics Data System (ADS)

    Ferriss, E.; Plank, T. A.; Walker, D.

    2013-12-01

    Accurate knowledge of the diffusion rates and mechanisms of water (hydrogen) in geologic materials is critical for geologic applications such as understanding the deep earth water cycle and determining ascent rates of pre-eruptive magmas. However, diffusion rates and mechanisms are often poorly known. Obtaining robust diffusion profile data for water with transmission FTIR traditionally requires cutting the sample after an experiment to isolate the central slice. Here we develop a method for interpreting diffusion profile data in three dimensions without cutting the sample. This 'whole-block' method is nondestructive, which simplifies the analytical procedure and allows multiple experiments on the same sample (e.g., a time series or reversal). Whole-block data represent concentration values that are integrated through the entire sample in the direction parallel to the infrared beam ray path during the measurement, and they are determined by taking the average value of a non-path-integrated 3 dimensional model (e.g., based on error functions or infinite sums in a rectangular parallelepiped) down the ray path for a given position. The whole-block method was tested by comparing whole-block profiles with profiles cut from the center of an oriented diopside sample after a dehydration experiment [1]. Water profiles were measured in the cut slice by both SIMS and FTIR. The results of the two methods are in good agreement both with each other and with diffusion profiles calculated based on the results of the whole-block method. Interpreting whole block measurements without taking into account the integration effects through the crystal can lead to errors in calculated diffusivities and inferred mechanisms. We have used numerical simulations to demonstrate as much as a half an order of magnitude error (typically indicating diffusivities that are too fast) if whole-block data are interpreted using non-path integrated diffusion models. The largest errors are in short and/or fast directions, in which diffusion profiles are well developed. Whole block data also inevitably involve central values that are contaminated by edge concentrations integrated in the signal. This integration effect results in a plateau in the whole-block data that may complicate the interpretation of the whole-block data. For example, previous experimental work on water diffusion in olivine has identified a central plateau using whole block measurements, and this plateau is interpreted to result from a transitional state between two diffusion mechanisms [2]. However, a whole-block model also produces a reasonable fit to this data using the observed initial concentration of zero and a single-step diffusion mechanism. Thus, whole block effects need to be taken into account for the accurate determination of diffusivities and mechanisms. [1] Ferriss et al 2012 AGU; [2] Demouchy&Mackwell 2006 Phys Chem Mineral 33(5).

  19. Generation of Forsteritic Olivine (Fo998) by Subsolidus Oxidation in Basaltic Flows

    E-print Network

    Meyers, Stephen R.

    Generation of Forsteritic Olivine (Fo99·8) by Subsolidus Oxidation in Basaltic Flows MADALYN S with compositions up to Fo99·8, which are found in multiple primitive basaltic lava flows from a monogenetic volcano in the Big Pine Volcanic Field, California, USA. In this study, we show that the forsterite in these basalts

  20. Author's personal copy Neon diffusion kinetics in olivine, pyroxene and feldspar

    E-print Network

    Shuster, David L.

    Author's personal copy Neon diffusion kinetics in olivine, pyroxene and feldspar: Retentivity of cosmogenic and nucleogenic neon Loraine Gourbet a,b , David L. Shuster b,c, , Greg Balco b , William S, pyroxene and feldspar to study diffusion kinetics of neon. This is important in evaluating the utility

  1. In situ Ultrasonic Velocity Measurements Across the Olivine-spinel Transformation in Fe2Si04

    SciTech Connect

    Liu, Q.; Liu, W; Whitaker, M; Wang, L; Li, B

    2010-01-01

    Compressional (P) and shear (S) wave velocities across the olivine-spinel transformation in Fe{sub 2}SiO{sub 4} were investigated in situ using combined synchrotron X-ray diffraction, X-ray imaging, and ultrasonic interferometry up to 5.5 GPa along the 1173 K isotherm. The onset of the spinel to olivine transformation at 4.5 GPa and olivine to spinel transition for Fe{sub 2}SiO{sub 4} at 4.8 GPa was concurrently observed from X-ray diffraction, the amplitude of the ultrasonic signals, the calculated velocities, and the ratio of P and S wave velocities (v{sub P}/v{sub S}). No velocity softening was observed prior to the fayalite to spinel transition. The velocity contrasts across the Fe{sub 2}SiO{sub 4} spinel to fayalite phase transition are derived directly from the measured velocities, which are 13 and 12% for P and S waves, respectively, together with a density contrast of 9.4%. A comparison with literature data indicates that the changes in compressional-wave velocity and density across the olivine-spinel transformation in Fe{sub 2}SiO{sub 4} are comparable to those with different iron concentrations in the (Mg,Fe){sub 2}SiO{sub 4} solid solution, whereas the shear wave velocity contrast decreases slightly with increasing iron concentration.

  2. The fate of fluid inclusions during high-temperature experimental deformation of olivine aggregates

    NASA Astrophysics Data System (ADS)

    Carter, Matthew J.; Zimmerman, Mark E.; Teyssier, Christian

    2015-05-01

    Torsion experiments on initially wet and dry olivine aggregates at equivalent deformation conditions investigated the fate of fluid inclusions (FIs) during high-temperature deformation. Wet samples were produced by adding water to San Carlos olivine powders before hot pressing; those hot pressed without water are considered dry. After hot pressing, wet and dry aggregates have comparable grain sizes, but wet aggregates have more abundant primary FIs. Talc jackets were fitted around some wet and dry samples prior to deformation to hydrate samples during deformation via talc dehydration at elevated temperature, whereas other samples were deformed without talc. At similar strain rates (~1.0 × 10-4 s-1), the peak shear stress for the dry sample (no talc) was 190-220 MPa, whereas all other samples reached 180 MPa; the strengths of wet (± talc) and dry (+ talc) specimens appear similar. Deformed samples reveal abundant FIs, reduced grain size, shape preferred orientation of olivine, and a pervasive low-angle fabric (C') to the shear plane defined by aligned FIs. Samples deformed with talc have FI-rich and FI-depleted domains; where FIs are abundant, the C' fabric is better developed and grain size is smaller. Electron backscatter diffraction pole figures suggest that olivine deformed in the dislocation creep regime via the (010)[100] slip system. Results of these experiments suggest that FIs are redistributed during dislocation creep, leading to the development of grain-scale, high-diffusivity pathways.

  3. An experimental study of the influence of graphite on the electrical conductivity of olivine aggregates

    E-print Network

    . Olivine aggregates containing diamonds were annealed to transform diamond to graphite with nearly equilibrium morphology. Graphite formed by the transformation from diamond has thin disk-shape morphology roughly the same amount in the mantle [Wood et al., 1996; Dasgupta and Hirschmann, 2010], and both

  4. Iron Partitioning in the Lower Mantle: New Experimental Data from Al-Enriched Olivine

    NASA Astrophysics Data System (ADS)

    Piet, H.; Nabiei, F.; Gillet, P.; Badro, J.

    2014-12-01

    The partitioning of iron between the major phases of the lower mantle has an important impact on their physical and chemical properties. A series of experimental studies of Fe-Mg exchange between bridgemanite (magnesium silicate perovskite) and ferropericlase have shown that stark differences in partitioning are observed if olivine [1, 2] or a pyrolitic [3, 4] starting composition are used. The discrepancy has been attributed to the presence of alumina, to that of ferric iron, to multiphase equilibria and even to the activity of FeO in the system. In order to mitigate the discrepancy, we synthesized a sample with San Carlos olivine composition that was doped in alumina. We then used this as starting material for experiments in the laser-heated diamond anvil cell at lower mantle (P,T) conditions along the geotherm. Samples were pressurized, heated, transformed to bridgemanite and ferropericlase, equilibrated, quenched, and decompressed. Thin sections were recovered from the hotspot using a focused ion beam microscope and the composition of the two phases was analyzed using analytical transmission electron microscopy. Iron partitioning in Al-rich olivine will be discussed through a detailed comparison with the Al-rich pyrolitic trend and the Al-free olivine trend. References [1] A-L. Auzende et al., Earth Planet. Sci. Lett., 2008. [2] R. Sinmyo et al., J. Geophys. Res., 2008.[3] R. Irifune et al., Science, 2010. [4] R. Sinmyo et al., Phys. Chem. Minerals, 2013.

  5. Mn-Cr ages of Fe-rich olivine in two Rumuruti (R) chondrites

    NASA Astrophysics Data System (ADS)

    Sugiura, N.; Miyazaki, A.

    2006-05-01

    Mn-Cr systematics in olivine of two Rumuruti (R) chondrites was investigated. Mn/52Cr ratios up to 1800 and 1300, and ?53Cr of up to 25° and 7° were observed for NWA 753 and Sahara 99531, respectively. All data points of NWA 753 show a linear correlation between ?53Cr values and Mn/52Cr ratios on the isochron diagram. The inferred initial 53Mn/55Mn ratio for NWA 753 is (1.84 ± 0.42(2?)) × 10-6. In the case of Sahara 99531, a positive correlation interpreted as an isochron for 53Mn/55Mn = 2.75 ± 1.55 (2?) × 10-6 was obtained for only one chondrule. Data from other chondrules in Sahara 99531 give an upper limit of 53Mn/55Mn = 0.49 × 10-6. The Mn-Cr ages of NWA 753 and a chondrule in Sahara 99531 are slightly older than that of the angrite LEW 86010 (Lugmair and Shukolyukov, 1998). Other chondrules in Sahara 99531 are at least 5 Ma younger than the LEW 86010. The Mn-Cr ages of olivine in R chondrites correspond to the time when olivine became a closed system either during slow cooling from the peak metamorphic temperature or during rapid cooling by impact excavation. In either case the olivine closure occurred earlier than the final assembly of the brecciated chondrites.

  6. Spinel from Apollo 12 Olivine Mare Basalts: Chemical Systematics of Selected Major, Minor, and Trace Elements

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Karner, J. M.; Shearer, C. K.; Spilde, M. N.

    2002-01-01

    Spinels from Apollo 12 Olivine basalts have been studied by Electron and Ion microprobe techniques. The zoning trends of major, minor and trace elements provide new insights into the conditions under which planetary basalts form. Additional information is contained in the original extended abstract.

  7. INVITED REVIEW Thermal infrared (vibrational) spectroscopy of MgFe olivines: A review and

    E-print Network

    Hamilton, Victoria E.

    in the minerals. Although band positions move to lower wavenumbers (longer wavelengths) across the forsterite common cations in olivine are Mg2 + and Fe2 + , forming a solid solution between forsterite (Mg2SiO4 of forsterite (Fo) and fayalite (Fa) (e.g., Fo90Fa10), or in shortened form, by just their forsterite number

  8. FeO IN CHONDRITIC OLIVINE: IMPLICATIONS FOR . L. Grossman1,2

    E-print Network

    and Si as pure forsterite and enstatite at tempera- tures above 1300K at most nebular pressures, in olivine is so low that diffusion of Fe into the pre- existing forsterite crystals ceases before XFa, where it would be nearly pure forsterite, and would reach XFa=0.20 at 1200K. At these high temperatures

  9. Midinfrared spectroscopy of synthetic olivines: Thermal emission, specular and diffuse reflectance, and attenuated total reflectance

    E-print Network

    Glotch, Timothy D.

    , and attenuated total reflectance studies of forsterite to fayalite Melissa D. Lane,1 Timothy D. Glotch,2 M. Darby] Synthetic olivine samples ranging in composition from forsterite to fayalite are analyzed in the midinfrared is identified of a specific emissivity maximum/reflectivity minimum (the flection position). From forsterite

  10. Effects of hydration on the elastic properties of olivine Steven D. Jacobsen,1

    E-print Network

    Duffy, Thomas S.

    and single-crystal elastic constants of hydrous forsterite (hy-Fo100) and hydrous olivine (hy-Fo97 obtain KS0 = 124.4(±0.4) GPa and G0 = 75.3(±0.3) GPa. Compared with anhydrous forsterite, the combined

  11. Phosphorus-rich olivine overgrowths: Evidence for additional impact to the Main Group pallasite parent body

    NASA Astrophysics Data System (ADS)

    Fowler-Gerace, Neva; Tait, Kimberly

    2015-04-01

    Phosphorus-rich olivine (1-7 wt% P2O5) is a metastable phase known from fewer than a dozen meteoritic or terrestrial occurrences. We have thoroughly examined P-rich olivine in the Springwater pallasite to characterise its distribution, textural relationships, and geochemical signature. P-rich olivine is abundant in Springwater as randomly distributed millimetre-scale partial overgrowths on the nominally P-free forsterite crystals. Geochemical analyses support the substitution mechanism of P into the tetrahedral Si site with octahedral site vacancies for charge balance; observed trace element variations, on the other hand, are not related to P substitution. Element mapping reveals fine-scale oscillatory P zoning in unusual serrate patterns, indicating rapid crystal nucleation from a melt and a subsequently variable rate of crystallisation. We constrain P-rich olivine formation in Springwater to at least 10-100 Myr subsequent to the introduction of the metal but before cooling below 700°C. Because the P-rich overgrowths overprint specific host grain boundary modifications, we suggest an impact to the Main Group pallasite parent body may have triggered the episode of extremely rapid cooling necessary to crystallise and preserve this rare phase.

  12. Gochimie des olivines plantaires : une approche micro-analytique par EPMA et LA-ICPMS

    E-print Network

    Cattin, Rodolphe

    Géochimie des olivines planétaires : une approche micro-analytique par EPMA et LA-ICPMS Directeur-louis BODINIER(Géochimie, Modélisation, DR) + Andrea TOMMASI (texture et petrophysique), Claude MERLET (Sonde électronique et ionique, IR), Olivier BRUGUIER (LA-(HR)ICP-MS, IR) Thématique : Sciences de la Terre et des

  13. Chlorine/Bromine Ratios in Fracture-filling Aqueous Alteration Products in Nakhla Olivine

    NASA Technical Reports Server (NTRS)

    Sutton, S. R.; Rao, M. N.; Dreibus, G.; McKay, D. S.; Waenke, H.; Wentworth, S.; Newville, M.; Trainor, T.; Flynn, G. J.

    2002-01-01

    The Cl/Br ratios in fracture-filling materials in veins in Nakhla olivine was determined using x-ray microprobe (Br) and EDX (Cl) techniques. The Cl/Br ratio of 55 (standard deviation: 13) shows that the secondary altered material is pristine, extraterrestrial and akin to the Martian soil. Additional information is contained in the original extended abstract.

  14. Influence of hydrogen on the electronic states of olivine: Implications for electrical conductivity

    E-print Network

    Influence of hydrogen on the electronic states of olivine: Implications for electrical conductivity; accepted 29 February 2012; published 28 March 2012. [1] The influence of hydrogen on the electronic states of electrons. We find that the dissolution of hydrogen modifies the electronic states when hydrogen

  15. Pyroxenes and olivines: Structural implications of shock-wave data for high pressure phases

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.; Ahrens, T. J.

    1975-01-01

    The nature of the shock-induced, high-pressure phases of olivine and pyroxene rocks is examined in the light of data for the densities of a new class of perovskite-related silicate structures. Also examined are some new Hugoniot and release adiabat data for bronzite. Reexamining available shock data for magnesian pyroxenes and olivines leads to the conclusion that they define a mixed phase (or disequilibrium) region to about the 100 GPa range, related to the kinetics of phase transformation in these silicates. By recognizing this point, certain discrepancies in previous interpretations of shock data can be explained. A set of theoretical Hugonoits for pyroxene and olivine stoichiometry, perovskite-bearing assemblages was constructed based on their properties deduced from high-pressure work, showing that the shock data is compatible with transformations to perovskites in the 45-7GPa region. Finally, the shock data indicate very similar properties for olivine and pyroxene at high pressures making them both equally likely candidates for the lower mantle.

  16. Correlative Microscopy and Visible/Near-Infrared Spectral Analysis of Simulated Solar Wind Implanted Olivine

    NASA Astrophysics Data System (ADS)

    Kuhlman, K. R.; Kvit, A. V.; Baba, K.; Poplawsky, J. D.; Hiroi, T.; Isheim, D.

    2015-11-01

    Here we present the results of the first atom probe tomography (APT) and scanning transmission electron microscopy study (STEM) of San Carlos olivine (Fo90.1) exposed to simulated solar wind-based space weathering due to hydrogen (~1keV/amu).

  17. Measurement of activation volume for creep of dry olivine at upper mantle pressure

    NASA Astrophysics Data System (ADS)

    Dixon, N. A.; Durham, W. B.; Suzuki, A. M.; Mei, S.; Kohlstedt, D. L.; Hustoft, J. W.

    2011-12-01

    Olivine is the most abundant and weakest phase in the upper mantle, and thus its rheological properties have a critical role in controlling convective flow in this region. A resilient obstacle to understanding the behavior of olivine in the mantle has been the difficulty of determining activation volume (V*), the influence of hydrostatic pressure on flow strength. The bulk of previous studies examining V* were conducted at low pressure (<300 MPa) and small pressure ranges in gas-medium deformation apparatuses, limiting precision and raising questions about application to relevant geological conditions. For this study, we conducted deformation experiments on dry polycrystalline olivine in the D-DIA apparatus. The development of a new hybrid soft-fired pyrophyllite/mullite sample assembly allowed for a broadened pressure range (2-9 GPa), while stress and strain were measured in-situ with synchrotron x rays. Refinement in diffraction technique has allowed stress resolution of ±0.01 GPa. For the pressure range in this study, we have measured an average activation volume of about 17 cm^3/mol for dry polycrystalline San Carlos olivine. This is a substantial pressure effect, representing a pressure-induced viscosity increase of nearly 7 orders of magnitude from the base of the lithosphere to the bottom of the upper mantle.

  18. The dissolution of olivine added to soil: Implications for enhanced P. Renforth a,b,

    E-print Network

    Jones, Peter JS

    online 27 May 2015 Editorial handling by M. Kersten a b s t r a c t Chemical weathering of silicateThe dissolution of olivine added to soil: Implications for enhanced weathering P. Renforth a,b, , P system on long timescales. Artificial acceleration of such weather- ing (``enhanced weathering'') has

  19. Methodology of Space Weathering Simulation and Its Application on Olivine and Pyroxene Samples

    NASA Astrophysics Data System (ADS)

    Malina, O.; Kohout, T.; Tucek, J.; Filip, J.; Britt, D.; Zboril, R.

    2015-11-01

    We reported here a new two-step thermal treatment method for the simulation of space weathering process in laboratory. The two-step synthesis method has been used for two different materials (olivine and pyroxene) and spectral changes were compared.

  20. PIGEONITE MASQUERADING AS OLIVINE AT MARS: FIRST RESULTS FROM MARS SPECTROSCOPY CONSORTIUM. C. M. Pieters1

    E-print Network

    Hiroi, Takahiro

    PIGEONITE MASQUERADING AS OLIVINE AT MARS: FIRST RESULTS FROM MARS SPECTROSCOPY CONSORTIUM. C. M has recently been established to ana- lyze whole rock and mineral separates from Mars mete- orites for whole rock analyses. The remaining mass was gently crushed by hand at Mt. Holyoke under acetone

  1. Deformation mechanisms of olivine single crystals compressed at 300 MPa and 800-1100°C

    NASA Astrophysics Data System (ADS)

    Cordier, Patrick; Demouchy, Sylvie; Mussi, Alexandre; Tommasi, Andrea

    2013-04-01

    Rheology of mantle rocks at lithospheric temperatures remains poorly constrained, since most experimental studies on creep mechanisms of olivine single crystals ((MgFe)2SiO4, Pbnm) and polycrystalline olivine aggregates were performed at high-temperatures (T >> 1200oC). In this study, we have performed deformation experiments on oriented single crystals of San Carlos olivine and polycrystalline olivine aggregate at temperatures relevant of the uppermost mantle (ranging from 800o to 1090oC) in tri-axial compression. The experiments were carried out at a confining pressure of 300 MPa in a high-resolution gas-medium mechanical testing apparatus at various constant strain rates (from 7 × 10-6 s-1 to 1 × 10-4 s-1). Mechanical tests yield differential stresses ranging from 88 to 1076 MPa. All samples were deformed at constant displacement rate and for finite strains ranging from 4 to 23 %, to provide insight into possible effects of hardening, softening or stick-and-slip. The single crystals were compressed along several crystallographic directions to test the possibility of activating different slip systems (e.g. [100](001), [001](100), [001](010) and [100](010)). We will present the characterization of the dislocation microstructures performed in the TEM.

  2. Methodology of Space Weathering Simulation and Its Application on Olivine and Pyroxene Samples

    NASA Astrophysics Data System (ADS)

    Malina, Ondrej; Kohout, Tomas; Tucek, Jiri; Filip, Jan; Britt, Daniel; Zboril, Radek

    2015-11-01

    Here, we reported a two-step thermal treatment method [1] for the space weathering simulation and the differences in the formation of metallic iron nanoparticles (npFe0) on the surface of olivine and pyroxene samples are discussed.In general, the main goal is in controlled size of npFe0 formed on the surface of olivine and pyroxene and in quantification of the related spectral changes. The transmission electron microscopy (TEM) after double-heating method revealed two significant features. First, different sizes and concentration of npFe0 are observed, and secondly, due to more resistance of pyroxene (e.g. [2]), higher temperatures are needed to produce the same amount of npFe0 as in the olivine case. [1]Results from TEM are fully consistent with reflectance spectra, which show progressive changes as a function of the increasing npFe0 amount. The reason for the observed differences in reflectance spectra can be found in the crystal structure and local environment at each crystallographic position of both samples. It is very similar as in the case of laser heating experiments (e.g. [2]), where the surface of orthopyroxene is significantly more resistant to reduction than olivine due to mobility of oxygen and cation diffusions from the bulk to surface of the samples.References:[1] Kohout T. et al. (2014) Icarus, 237, 75-83[2] Quadery A. et al (2015) JGR-Planets 120, 1-19.

  3. Oxygen isotope heterogeneity and disequilibria of olivine crystals in large volume Holocene basalts from Iceland: Evidence

    E-print Network

    Bindeman, Ilya N.

    Oxygen isotope heterogeneity and disequilibria of olivine crystals in large volume Holocene basalts glass is relatively homogeneous with respect to oxygen isotopes, plagioclase phenocrysts exhibit crystal ), Nu´pahraun (ca. 4000 BP, >1 km3 ) and Thjo´rsa´rhraun (ca 8000 BP, >20 km3 ). We present oxygen

  4. Crystallographic preferred orientations and melt-rock interactions : olivine-rich troctolites from IODP Hole U1309D

    NASA Astrophysics Data System (ADS)

    Drouin, M.; Ildefonse, B.; Hirth, G.; Waters, C. L.; Godard, M.

    2010-12-01

    IODP Expeditions 304-305 sampled the Atlantis Massif, an oceanic core complex located at 30°N in the inside corner of the intersection of the Mid-Atlantic Ridge with the Atlantis Fracture Zone. The most primitive end-members of the recovered gabbroic sequence, olivine-rich troctolites (ol > ~70%), have textures and geochemical compositions intermediate between those of mantle peridotites and primitive cumulates, indicative of melt impregnation processes (Drouin et al., 2009). Olivine-rich troctolites from Hole U1309D (about 5% of recovered rocks) display poikilitic textures, with olivine ranging from coarse-grained subhedral crystals, commonly containing well-developed subgrains, to medium-grained rounded crystals with fewer or no substructures. Olivine substructures reveal dislocation creep that is consistent with activation of the main high-temperature slip systems, dominantly (010)[100]. Olivine crystallographic preferred orientation is very weak, but generally shows a relatively stronger, uncommon [001] concentration (Drouin et al., 2010). These unusual olivine fabrics are interpreted as resulting from dunitisation and melt impregnation of a previously deformed olivine matrix; the solid olivine framework is eventually disrupted by olivine corrosion along grain and subgrain boundaries, and the high-temperature plastic fabric is modified in a liquid-dominated regime. Similar fabrics are described in impregnated peridotites from the mantle/crust transition zone in the Oman ophiolite. A reduction of fabric strength in the presence of melt is also documented in deformation experiments performed in a gas-medium high-pressure high-temperature vessel. Experiments were conducted with olivine + melt (10 to 30 wt%) isostatically hot-pressed initial material. The olivine crystallographic preferred orientation is weaker in deformed sampled than in the undeformed hot pressed material. We propose that very weak fabrics such as those measured in the Atlantis Massif olivine-rich troctolites, in this case with unusual preferred [001] maxima, are a common result of melt-rock interactions in melt-impregnated peridotites or ultramafic cumulates in mid-ocean ridge environments. The joint study of in situ crystal geochemistry and microstructures is needed to characterize complex crystallization histories in open system with percolation of large volume of MORB-type melt that postdate olivine crystal-plastic deformation. - Drouin, M., Godard, M., Ildefonse, B., Bruguier, O., and Garrido, C., 2009. Chem. Geol., doi:10.1016/j.chemgeo.2009.02.013 - Drouin, M., B. Ildefonse, and M. Godard, 2010. Geochem. Geophys. Geosyst., doi:10.1029/2009GC002995

  5. Origin of Aristarchus Olivine Deposits Based on M3, WAC, and Diviner Analyses

    NASA Astrophysics Data System (ADS)

    Wiseman, S. M.; Mustard, J. F.; Donaldson Hanna, K. L.; Isaacson, P.; Jolliff, B. L.; Besse, S.; Staid, M.; Pieters, C. M.

    2011-12-01

    The Aristarchus region contains geologically diverse deposits and the Aristarchus impact crater, located on the SE margin of the plateau near the contact between plateau materials and western Procellarum basalts, has exposed materials with variable compositions. Of particular interest is the origin of olivine-bearing deposits that occur on the SE portion of the crater rim and ejecta in association with impact melt [1]. NW portions of the rim and ejecta expose plateau materials and are spectrally dominated by pyroxene in the VNIR. Spectra of the NW rim and ejecta are consistent with a noritic composition and with the inferred origin of the plateau as uplifted upper crust [2,3,4]. Therefore, it is unlikely that the olivine- bearing materials, which exhibit a strong 1 micron olivine absorption and only minor pyroxene contributions, are derived from plateau materials similar to those exposed in the NW portion of the crater. Potential sources of the olivine-bearing material excavated by the impact include western Procellarum basalts or buried material associated with the Marius Hills volcanic complex. Alternatively, the olivine-bearing deposits could be derived from a shallow pluton that is not represented by other surface exposures or could have formed as re-crystallized impact melt. Both the western Procellarum basalts [5,6] and some units associated with the Marius Hills [7] are olivine-bearing. In order to differentiate between these hypotheses, we are integrating spectral data in the UV/VIS (LRO WAC), VIS/NIR (Chandrayaan-1 M3), and TIR (LRO Diviner) to further characterize the assemblages of minerals that occur in association with the olivine-bearing deposits in Aristarchus crater, western Procellarum, and units within the Marius Hills volcanic complex. [1] Mustard et al., 2011, JGR 116. [2] McEwen et al., 1994, Science 266. [3] Lucey et al., 1986, LPSC 16. [4] Chevrel et al., 2009, Icarus 199. [5] Staid and Pieters 2001, JGR. [6] Staid et al., 2011, JGR 116. [7] Besse et al., 2011, JGR 116.

  6. UNDERSTANDING OLIVINE CO2 MINERAL SEQUESTRATION MECHANISMS AT THE ATOMIC LEVEL: OPTIMIZING REACTION PROCESS DESIGN

    SciTech Connect

    M.J. McKelvy; H. Bearat; A.V.G. Chizmeshya; R. Nunez; R.W. Carpenter

    2003-08-01

    Carbonation of Mg-rich minerals offers an intriguing candidate carbon sequestration process technology, which can provide large-scale CO{sub 2} disposal. Such disposal bypasses many long-term storage problems by (i) providing containment in the form of mineral carbonates that have proven stable over geological time, (ii) generating only environmentally benign materials, and (iii) essentially eliminating the need for continuous site monitoring. The primary challenge for viable process development is reducing process cost. This is the primary focus of the CO{sub 2} Mineral Sequestration Working Group managed by Fossil Energy at DOE, which includes members from the Albany Research Center, Los Alamos National Laboratory, the National Energy Technology Laboratory, Penn State University, Science Applications International Corporation, and the University of Utah, as well as from our research group at Arizona State University. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a leading process candidate, which converts CO{sub 2} into the mineral magnesite (MgCO{sub 3}). As olivine carbonation is exothermic, it offers intriguing low-cost potential. Recent studies at the Albany Research Center have found aqueous-solution carbonation is a promising approach. Cost effectively enhancing carbonation reactivity is central to reducing process cost. Many of the mechanisms that impact reactivity occur at the solid/solution interface. Understanding these mechanisms is central to the ability to engineer new and modified processes to enhance carbonation reactivity and lower cost. Herein, we report the results of our UCR I project, which focused on exploring the reaction mechanisms that govern aqueous-solution olivine carbonation using model olivine feedstock materials. Carbonation was found to be a complex process associated with passivating silica layer formation, which includes the trapping of magnesite nanocrystals within the passivating silica layers, cracking and exfoliation of the layers, silica surface migration, olivine etch pit formation, transfer of the Mg and Fe in the olivine into the product carbonate, and the nucleation and growth of magnesite crystals on/in the silica/olivine reaction matrix. These phenomena occur in concert with the large solid volume changes that accompany the carbonation process, which can substantially impact carbonation reactivity. Passivating silica layer formation appears to play a major role in inhibiting carbonation reactivity. New approaches that can mitigate the effectiveness of passivating layer formation may offer intriguing potential to enhance carbonation reactivity and lower process cost.

  7. Elasticity of single-crystal olivine at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Mao, Zhu; Fan, Dawei; Lin, Jung-Fu; Yang, Jing; Tkachev, Sergey N.; Zhuravlev, Kirill; Prakapenka, Vitali B.

    2015-09-01

    Elasticity of single-crystal San Carlos olivine has been derived from sound velocity and density measurements at simultaneous high pressure-temperature conditions up to 20 GPa and 900 K using in situ Brillouin spectroscopy and single-crystal X-ray diffraction in externally-heated diamond anvil cells. These experimental results are used to evaluate the combined effect of pressure and temperature on full elastic constants of single-crystal olivine to better understand its velocity profiles and anisotropies in the deep mantle. Analysis of the results shows that the shear moduli display strong concave behaviors as a function of pressure at a given high temperature, while the longitudinal modulus, C11, and the off-diagonal moduli, C12 and C13, exhibit greater temperature dependence at higher pressures than at relatively lower pressures. Using a finite-strain theory and thermal equation of state modeling for a pyrolitic mantle composition along an expected mantle geotherm, our results show that the magnitude of the VP and VS jumps at the 410-km depth are 6% and 6.4%, respectively, which are greater than that found in seismic observations, suggesting a mantle olivine content of 40-50 vol%, which is less than what is expected for the pyrolite model. Our modeled velocity profiles for a metastable olivine wedge in the subduction slabs along a representative cold slab geotherm are 6% and 10% lower than those of wadsleyite and ringwoodite, respectively, at corresponding depths of the normal mantle. Our modeled results also show that metastable olivine in the cold slabs could have strong VP and VS anisotropies. The maximum VP anisotropy is estimated to be 19-22% at transition zone depth, whereas the maximum VS splitting is 13-23% and increases with depth. As a result, the presence of a metastable olivine wedge at the transition zone depth would exhibit a seismic signature of low velocity and strong seismic anisotropy which are consistent with recent seismic observations for various locations of the slabs and can be used as mineral physics constraints for future seismic detections of the metastable olivine wedges in the deep mantle.

  8. Kinetics of the olivine-ringwoodite transformation and seismic attenuation in the Earth's mantle transition zone

    NASA Astrophysics Data System (ADS)

    Perrillat, J. P.; Chollet, M.; Durand, S.; van de Moortèle, B.; Chambat, F.; Mezouar, M.; Daniel, I.

    2016-01-01

    In regions of the mantle where multi-phases coexist like at the olivine-wadsleyite-ringwoodite transitions, the stress induced by the seismic waves may drive a mineralogical reaction between the low to high pressure phases, a possible source of dissipation. In such a situation, the amount of attenuation critically depends on the timescale for the phase transformations to reach equilibrium relative to the period of the seismic wave. Here we report synchrotron-based measurements of the kinetics of the olivine to ringwoodite transformation at pressure-temperature conditions of the co-stability loop, for iron-rich olivine compositions. Both microstructural and kinetic data suggest that the transformation rates are controlled by growth processes after the early saturation of nucleation sites along olivine grain boundaries. Transformation-time data show an increase of reaction rates with temperature and iron content, and have been fitted to a rate equation for interface-controlled transformation: G =k0 ? T ? exp ? [ n ?XFa ] ? exp ? [ - (?Ha + PV*) / RT ] × [ 1 - exp ? (?Gr / RT) ], where XFa is the fayalite fraction, the exponential factor n = 9.7, ln ?k0 = - 9.1 ms-1. XFa-1 and ?Ha = 199 kJ /mol, assuming V* = 0 cm3 /mol. Including these new kinetic results in a micro-mechanical model of a two-phase loop (Ricard et al., 2009), we predict QK-1 and Q?-1 significantly higher than the PREM values for both body waves and normal modes. This attests that the olivine-wadsleyite transition can significantly contribute to the attenuation of the Earth's mantle transition zone.

  9. Microstructural development in olivine aggregates during dislocation creep under hydrous conditions

    NASA Astrophysics Data System (ADS)

    Tasaka, M.; Zimmerman, M. E.; Kohlstedt, D. L.

    2014-12-01

    Since hydrogen plays an important role in dynamic processes in the mantle, we conducted high-strain torsion experiments on aggregates of Fe-bearing olivine [(Mg,Fe)2SiO4; Fo50] under hydrous condition. Olivine with a composition of Fo50 was used because of its enhanced grain growth kinetics and low strength relative to Fo90. Two pieces of an oriented San Carlos olivine crystal were embedded in the aggregates to monitor water fugacity both before and after deformation. We deformed samples to high enough strain, ? ? 4, to achieve a steady-state microstructure. A non-linear, least-squares fit to the stress versus strain rate data yielded a stress exponent, n ? 3.5, indicative of deformation involving dislocations. The water content determined from Fourier transform infrared (FTIR) spectroscopy analyses of the single crystals demonstrate that the samples are water saturated after deformation. Fabric analyses of the polycrystalline olivine samples, determined using electron backscatter diffraction (EBSD), indicate that the strength of the lattice preferred orientation (LPO) increases with increasing strain. Further, at low strain, ? < 2, two slip systems contribute to deformation: (i) [100] axes parallel to the shear direction with the [001] axes normal to the shear plane, indicative of the (001)[100] slip system, plus (ii) [001] axes are parallel to the shear direction with the [100] axes normal to the shear plane, suggestive of the (100)[001] slip system. With increasing strain, the LPO evolves until (100)[001] becomes the dominant slip system at ? > 3. We interpret the observed fabric evolution to represent the competition between the two easiest slip systems in olivine, (100)[001] and (001)[100]. The evolution of fabric can be applied to investigations of upper mantle seismic anisotropy especially in a mantle wedge or in a shear zone, locations in which hydrous conditions prevail.

  10. The Nature and Role of Kinking in Olivine Deformation at High Pressure

    NASA Astrophysics Data System (ADS)

    Burnley, P. C.; Cline, C. J., II; Drue, A.

    2011-12-01

    A significant challenge for modeling the deformation of polycrystalline olivine is understanding the accommodation mechanisms operating in olivine grains that are not well oriented for slip. One such accommodation mechanism is kinking. We have studied kinking in experimentally deformed polycrystalline Mg2GeO4 olivine using electron backscatter diffraction. We find that some degree of kinking occurs in all grains for which the angle between [001] and the compression direction is less than 35 degrees. All of the kinked grains we measured have kinks that rotate the kinked domains about the [010] axis and have kink band boundaries that cluster about the (001) plane. Thus we conclude that the kinks have formed on the [001](100) slip system. The maximum degree of rotation between the kink bands within a single grain varies between about 4 and 75 degrees. Although the kink band boundaries are quite sharp, the amount of rotation about the [010] axis varies continuously between the minimum and maximum within each kinked grain. Thus, there is a substantial amount of deformation within each kinked domain. Several conclusions can be drawn from this study: 1) At the conditions at which these samples were deformed [001](100) is the dominant slip system in Mg2GeO4 olivine. This is consistent with recent observation by other groups that [001] slip becomes the dominant slip system in (Mg,Fe)2SiO4 olivine at high pressure. 2) In a randomly oriented polycrystal deforming plastically via [001](100) slip, ~18% of the grains will accommodate shortening by kinking. This result will be useful for modeling studies.

  11. Dislocation-accommodated grain boundary sliding as the major deformation mechanism of olivine in the Earth's upper mantle.

    PubMed

    Ohuchi, Tomohiro; Kawazoe, Takaaki; Higo, Yuji; Funakoshi, Ken-Ichi; Suzuki, Akio; Kikegawa, Takumi; Irifune, Tetsuo

    2015-10-01

    Understanding the deformation mechanisms of olivine is important for addressing the dynamic processes in Earth's upper mantle. It has been thought that dislocation creep is the dominant mechanism because of extrapolated laboratory data on the plasticity of olivine at pressures below 0.5 GPa. However, we found that dislocation-accommodated grain boundary sliding (DisGBS), rather than dislocation creep, dominates the deformation of olivine under middle and deep upper mantle conditions. We used a deformation-DIA apparatus combined with synchrotron in situ x-ray observations to study the plasticity of olivine aggregates at pressures up to 6.7 GPa (that is, ~200-km depth) and at temperatures between 1273 and 1473 K, which is equivalent to the conditions in the middle region of the upper mantle. The creep strength of olivine deforming by DisGBS is apparently less sensitive to pressure because of the competing pressure-hardening effect of the activation volume and pressure-softening effect of water fugacity. The estimated viscosity of olivine controlled by DisGBS is independent of depth and ranges from 10(19.6) to 10(20.7) Pa·s throughout the asthenospheric upper mantle with a representative water content (50 to 1000 parts per million H/Si), which is consistent with geophysical viscosity profiles. Because DisGBS is a grain size-sensitive creep mechanism, the evolution of the grain size of olivine is an important process controlling the dynamics of the upper mantle. PMID:26601281

  12. Dislocation-accommodated grain boundary sliding as the major deformation mechanism of olivine in the Earth’s upper mantle

    PubMed Central

    Ohuchi, Tomohiro; Kawazoe, Takaaki; Higo, Yuji; Funakoshi, Ken-ichi; Suzuki, Akio; Kikegawa, Takumi; Irifune, Tetsuo

    2015-01-01

    Understanding the deformation mechanisms of olivine is important for addressing the dynamic processes in Earth’s upper mantle. It has been thought that dislocation creep is the dominant mechanism because of extrapolated laboratory data on the plasticity of olivine at pressures below 0.5 GPa. However, we found that dislocation-accommodated grain boundary sliding (DisGBS), rather than dislocation creep, dominates the deformation of olivine under middle and deep upper mantle conditions. We used a deformation-DIA apparatus combined with synchrotron in situ x-ray observations to study the plasticity of olivine aggregates at pressures up to 6.7 GPa (that is, ~200-km depth) and at temperatures between 1273 and 1473 K, which is equivalent to the conditions in the middle region of the upper mantle. The creep strength of olivine deforming by DisGBS is apparently less sensitive to pressure because of the competing pressure-hardening effect of the activation volume and pressure-softening effect of water fugacity. The estimated viscosity of olivine controlled by DisGBS is independent of depth and ranges from 1019.6 to 1020.7 Pa·s throughout the asthenospheric upper mantle with a representative water content (50 to 1000 parts per million H/Si), which is consistent with geophysical viscosity profiles. Because DisGBS is a grain size–sensitive creep mechanism, the evolution of the grain size of olivine is an important process controlling the dynamics of the upper mantle. PMID:26601281

  13. Olivine in Martian Meteorite Allan Hills 84001: Evidence for a High-Temperature Origin and Implications for Signs of Life

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Leshin, L. A.; Adcock, C. T.

    1999-01-01

    Olivine from Martian meteorite Allan Hills (ALH) 84001 occurs as clusters within orthopyroxene adjacent to fractures containing disrupted carbonate globules and feldspathic shock glass. The inclusions are irregular in shape and range in size from approx. 40 microns to submicrometer. Some of the inclusions are elongate and boudinage-like. The olivine grains are in sharp contact with the enclosing orthopyroxene and often contain small inclusions of chromite The olivine exhibits a very limited range of composition from Fo(sub 65) to Fo(sub 66) (n = 25). The delta(sup 18)O values of the olivine and orthopyroxene analyzed by ion microprobe range from +4.3 to +5.3% and are indistinguishable from each other within analytical uncertainty. The mineral chemistries, O-isotopic data, and textural relationships indicate that the olivine inclusions were produced at a temperature greater than 800 C. It is unlikely that the olivines formed during the same event that gave rise to the carbonates in ALH 84001, which have more elevated and variable delta(sup 18)O values, and were probably formed from fluids that were not in isotopic equilibrium with the orthopyroxene or olivine The reactions most likely instrumental in the formation of olivine could be either the dehydration of hydrous silicates that formed during carbonate precipitation or the reduction of orthopyroxene and spinel If the olivine was formed by either reaction during a postcarbonate beating event, the implications are profound with regards to the interpretations of McKay et al. Due to the low diffusion rates in carbonates, this rapid, high-temperature event would have resulted in the preservation of the fine-scale carbonate zoning' while partially devolatilizing select carbonate compositions on a submicrometer scale. This may have resulted in the formation of the minute magnetite grains that McKay et al attributed to biogenic activity.

  14. Olivine Weathering in Soil, and Its Effects on Growth and Nutrient Uptake in Ryegrass (Lolium perenne L.): A Pot Experiment

    PubMed Central

    ten Berge, Hein F. M.; van der Meer, Hugo G.; Steenhuizen, Johan W.; Goedhart, Paul W.; Knops, Pol; Verhagen, Jan

    2012-01-01

    Mineral carbonation of basic silicate minerals regulates atmospheric CO2 on geological time scales by locking up carbon. Mining and spreading onto the earth's surface of fast-weathering silicates, such as olivine, has been proposed to speed up this natural CO2 sequestration (‘enhanced weathering’). While agriculture may offer an existing infrastructure, weathering rate and impacts on soil and plant are largely unknown. Our objectives were to assess weathering of olivine in soil, and its effects on plant growth and nutrient uptake. In a pot experiment with perennial ryegrass (Lolium perenne L.), weathering during 32 weeks was inferred from bioavailability of magnesium (Mg) in soil and plant. Olivine doses were equivalent to 1630 (OLIV1), 8150, 40700 and 204000 (OLIV4) kg ha?1. Alternatively, the soluble Mg salt kieserite was applied for reference. Olivine increased plant growth (+15.6%) and plant K concentration (+16.5%) in OLIV4. At all doses, olivine increased bioavailability of Mg and Ni in soil, as well as uptake of Mg, Si and Ni in plants. Olivine suppressed Ca uptake. Weathering estimated from a Mg balance was equivalent to 240 kg ha?1 (14.8% of dose, OLIV1) to 2240 kg ha?1 (1.1%, OLIV4). This corresponds to gross CO2 sequestration of 290 to 2690 kg ha?1 (29 103 to 269 103 kg km?2.) Alternatively, weathering estimated from similarity with kieserite treatments ranged from 13% to 58% for OLIV1. The Olsen model for olivine carbonation predicted 4.0% to 9.0% weathering for our case, independent of olivine dose. Our % values observed at high doses were smaller than this, suggesting negative feedbacks in soil. Yet, weathering appears fast enough to support the ‘enhanced weathering’ concept. In agriculture, olivine doses must remain within limits to avoid imbalances in plant nutrition, notably at low Ca availability; and to avoid Ni accumulation in soil and crop. PMID:22912685

  15. Mineralogy and Petrology of Amoeboid Olivine Inclusions in CO3 Chondrites: Relationship to Parent-Body Aqueous Alteration

    NASA Technical Reports Server (NTRS)

    Chizmadia, Lysa J.; Rubin, Alan E.; Wasson, John T.

    2003-01-01

    Petrographic and mineralogic studies of amoeboid olivine inclusions (AOIs) in CO3 carbonaceous chondrites reveal that they are sensitive indicators of parent-body aqueous and thermal alteration. As the petrologic subtype increases from 3.0 to 3.8, forsteritic olivine (Fa(sub 0-1)) is systematically converted into ferroan olivine (Fa(sub 60-75)). We infer that the Fe, Si and O entered the assemblage along grain boundaries, forming ferroan olivine that filled fractures and voids. As temperatures increased, Fe(+2) from the new olivine exchanged with Mg(+2) from the original AOI to form diffusive haloes around low-FeO cores. Cations of Mn(+2), Ca(+2) and Cr(+3) were also mobilized. The systematic changes in AOI textures and olivine compositional distributions can be used to refine the classification of CO3 chondrites into subtypes. In subtype 3.0, olivine occurs as small forsterite grains (Fa(sub 0-1)), free of ferroan olivine. In petrologic subtype 3.2, narrow veins of FeO-rich olivine have formed at forsterite grain boundaries. With increasing alteration, these veins thicken to form zones of ferroan olivine at the outside AOI margin and within the AOI interior. By subtype 3.7, there is a fairly broad olivine compositional distribution in the range Fa(sub 63-70), and by subtype 3.8, no forsterite remains and the high-Fa peak has narrowed, Fa(sub 64-67). Even at this stage, there is incomplete equilibration in the chondrite as a whole (e.g., data for coarse olivine grains in Isna (CO3.8) chondrules and lithic clasts show a peak at Fa(sub39)). We infer that the mineral changes in A01 identified in the low petrologic types required aqueous or hydrothermal fluids whereas those in subtypes greater than or equal to 3.3 largely reflect diffusive exchange within and between mineral grains without the aid of fluids.

  16. Potential Temperatures of Sources of MORB, OIB and LIPs Based on AL Partitioning Between Olivine and Spinel

    NASA Astrophysics Data System (ADS)

    Sobolev, A. V.; Batanova, V. G.; Krasheninnikov, S.; Borisov, A.; Arndt, N.; Kuzmin, D.; Krivolutskaya, N.; Sushevskaya, N.

    2013-12-01

    Knowledge of potential temperatures of convecting mantle is required for the understanding the global processes on the Earth [1]. The common way to estimate these is the reconstruction of primary melt compositions and liquidus temperatures based on the Fe-Mg partitioning between olivine and melt. This approach requires knowledge of the compositions of primitive melts in equilibrium with olivine alone as well as composition of olivine equilibrium with primary melts. This information is in most cases unavailable or of questionable quality. Here we report a new approach to obtain crystallization temperatures of primary melts based on the olivine-spinel Al-Cr geothermometer [2]. The advantages of this approach are: (1) low rate of diffusion of Al in the olivine, which promises to preserve high magmatic temperatures and (2) common presence of spinel in assemblage with high-Mg olivine. In order to decipher influence of elevated Ti concentrations in spinel we have run several experiments at high temperatures (1400-1200 degree C), atmospheric pressure and controled oxygen fugacity. We also analysed over two thousand spinel inclusions and high-Mg host olivines from different MORB, OIB, LIP and Archean komatiites on the JXA-8230 EPMA at ISTerre, Grenoble, France. Concentrations of Al, Ti, Na, P, Zn, Cr, Mn, Ca, Co, Ni were determined with a precision of 10 ppm (2 standard errors) using a newly developed protocol [3]. When available, we also analysed matrix glass and glass inclusions in olivine and found that temperature estimations from olivine-spinel (Al-Cr) and olivine-melt (Fe-Mg) [4] equilibrium match within (+/-30 degree C). The results show contrasting crystallization temperatures of Mg-rich olivine of the same Fo content from different types of mantle-derived magmas, from the lowest (down to 1220 degree C) for MORB to the highest (up to 1550 degree C) for komatiites and Siberian meimechites. These results match predictions from Fe-Mg olivine-melt equilibrium and confirm the relatively low temperature of the convecting mantle source of MORB and higher temperatures in the mantle plumes that produce the OIB of Iceland, Hawaii, Gorgona, Archean komatiites and several LIPs (e.g. Siberian, Decan). [1] McKenzie & Bickle, 1988, J. Petr. 29, p 625-679. [2] Wan et al, 2008, Am. Min. 93, p1142-1147. [3] Batanova & Sobolev, 2013, Min. Mag.,p 667, DOI :10.1180/minmag2013.077.5.2 [4] Ford et al, 1983, J. Petr. 24, p 256-265.

  17. Reduced chromium in olivine grains from lunar basalt 15555: X-ray absorption near edge structure (XANES)

    SciTech Connect

    Sutton, S.R.; Rivers, M.L.; Bajt, S.; Smith, J.V. Brookhaven National Lab., Upton, NY ); Jones, K.W.; Gordon, B. )

    1993-01-01

    The oxidation state of Cr in 200 [mu]m regions within individual lunar olivine and pyroxene grains from lunar basalt 15555 was inferred using X-ray Absorption Near Edge Structure (XANES). Reference materials had previously been studied by optical absorption spectroscopy and included Cr-bearing borosilicate glasses synthesized under controlled oxygen fugacity and Cr-doped olivines. The energy dependence of XANES spectral features defined by these reference materials indicated that Cr is predominantly divalent in the lunar olivine and trivalent in the pyroxene. These results coupled with the apparent f[sub o[sub 2

  18. Rock magnetic properties of dusty olivine: comparison and calibration of non-heating paleointensity methods

    NASA Astrophysics Data System (ADS)

    Lappe, S. L.; Harrison, R. J.; Feinberg, J. M.

    2012-12-01

    The mechanism of chondrule formation is an important outstanding question in cosmochemistry. Magnetic signals recorded by Fe-Ni nanoparticles in chondrules could carry clues to their origin. Recently, research in this area has focused on 'dusty olivine' in ordinary chondrites as potential carriers of pre-accretionary remanence. Dusty olivine is characterised by the presence of sub-micron Fe-Ni inclusions within the olivine host. These metal particles form via subsolidus reduction of the olivine during chondrule formation and are thought to be protected from subsequent chemical and thermal alteration by the host olivine. Three sets of synthetic dusty olivines have been produced, using natural olivine (average Ni-content of 0.3 wt%), synthetic Ni-containing olivine (0.1wt% Ni) and synthetic Ni-free olivine as starting materials. The starting materials were ground to powders, packed into a 8-27 mm3 graphite crucible, heated up to 1350°C under a pure CO gas flow and kept at this temperature for 10 minutes. After this the samples were held in fixed orientation and quenched into water in a range of known magnetic fields from 0.2 mT to 1.5 mT. We present a comparison of all non-heating methods commonly used for paleointensity determination of extraterrestrial material. All samples showed uni-directional, single-component demagnetization behaviour. Saturation REM ratio (NRM/SIRM) and REMc ratio show non-linear behaviour as function of applied field and a saturation value < 1. Using the REM' method the samples showed approximately constant REM' between 100 and 150 mT AF-field. Plotting the average values for this field range again shows non-linear behaviour and a saturation value < 1. Another approach we examined to obtain calibration curves for paleointensity determination is based on ARM measurents. We also present an analysis of a new FORC-based method of paleointensity determination applied to metallic Fe-bearing samples [1, 2]. The method uses a first-order reversal curve (FORC) diagram to generate a Preisach distribution of coercivities and interaction fields within the sample and then physically models the acquisition of TRM as function of magnetic field, temperature and time using thermal relaxation theory. The comparison of observed and calculated NRM demagnetisation spectra is adversely effected by a large population of particles in the single-vortex state. Comparison of observed and calculated REM' curves, however, yields much closer agreement in the high-coercivity SD-dominated range. Calculated values of the average REM' ratio show excellent agreement with the experimental values - including the observed non-linearity of the remanence acquisition curve - suggesting that this method has the potential to reduce the uncertainties in non-heating paleointensity methods for extraterrestrial samples. [1] AR Muxworthy and D Heslop(2011) A Preisach method for estimating absolute paleofield intensity under the constraint of using only isothermal measurements: 1. Theoretical framework. Journal of Geophysical Research, 116, B04102, doi:10.1029/2010JB007843. [2] AR Muxworthy, D Heslop, GA Paterson, and D Michalk. A Preisach method for estimating absolute paleofield intensity under the constraint of using only isothermal measurements: 2. Experimental testing. Journal of Geophysical Research, 116, B04103, doi:10.1029/2010JB007844.

  19. Volatile Content in Melt Inclusions in Variable &?18O Olivines From Klyuchevskoy Volcano, Kamchatka, Russia.

    NASA Astrophysics Data System (ADS)

    Auer, S. L.; Bindeman, I.; Ponomareva, V.; Wallace, P.

    2005-12-01

    Klyuchevskoy group volcanos in the Central Kamchatka Depression have the highest magma production rates in the world. Among these, the 4750m high Klyuchevskoy volcano, only approximately 7000 years old, erupts every 5 to 10 years, with the latest summit eruption in March 2005. Magma compositions range from high-Al to high-Mg basalt and basaltic andesite with 5 to 11 wt% MgO. Mg-rich olivines are present throughout the different magma compositions, and range in Fo content from 92 to 75%. Klyuchevskoy basalts also exhibit the highest ?18O in the world with d18O olivine ranging from 5.6 to 7.2 ‰, including olivines of this study. To constrain the primary volatile concentrations of the parental magmas, we analyzed H2O in olivine-hosted melt inclusions from tephrochronologically-dated tephra layers on the flanks of the volcano. Analyzed samples include three tephra layers of high-Al composition and one high-Mg sample. Olivine from these tephra layers span 1.5 permil in d18O from high-d18O to normal-d18O values. The range in H2O contents of melt inclusions from each tephra layer are similar (0.9 to >4 wt% H2O) the latter numbers being higher than measured previously for Klyuchevskoy, but similar to maximum values found for some other arc basalts. In particular, even high-Mg basalts have high H2O concentration, which we believe reflects a primary magma signature. Melt inclusions with lower H20 contents were probably trapped from partially degassed melts at various depths during ascent and/or represent recycling of low pressure, variable Fo olivines that were syneruptively entrained in magma. We are correlating the measured volatile concentrations with Mg#, d18O, age, and metl inclusion composition, but the preliminary results suggest only subtle correlations. These are studied in an attempt to explain the origin of the uniquely high-d18O signature of Klyuchevskoy as being a primary signature of high-d18O subduction fluids vs. assimilation of water bearing, high-d18O crustal compositions. Additionally, the petrogenetic history of high-Al and high-Mg basalts seem to be intertwined in the sampled Klyuchevskoy tephrochronological record.

  20. Weathering of olivine and pyroxene on Mars: Evidence from missions, meteorites, and terrestrial mineral analogs

    NASA Astrophysics Data System (ADS)

    Velbel, M. A.

    2010-12-01

    Mineral-water interactions modify primary minerals, produce new minerals as alteration products, and modify the solute loads of the solutions. Except for situations in which the solutions still coexist with reactant and product minerals, properties of the solutions (e.g., the abundances of various solutes; the duration of their contact with the minerals) must be inferred from the mineral assemblages left behind. Abundant literature exists on identifying and interpreting the paleoenvironmental significance of mineral products of such reactions on Mars (e.g., clay minerals and other phyllosilicates; sulfates; carbonates). Less literature exists on interpreting the paleoenvironmental significance of primary minerals and their properties in altered Mars materials. Since the arrival of the Mars Exploration Rovers in 2004 and the Phoenix Mars Lander in 2008, a number of new observations of primary-mineral destruction have been enabled by deployment of microscopic imagers on Mars and continued microscopic investigation of Mars meteorites in terrestrial laboratories. These include examples of alteration of both of the major minerals of Mars’ igneous rocks, olivine and pyroxene. Olivine alteration is indicated by selective removal of euhedral olivine from weathered rinds on basalt at Gusev crater, and elongate cavities of non-uniform width in olivine in the Mars meteorite Nakhla; the latter exhibit some similarities to and some differences from common arrays of corrosion pits on weathered terrestrial olivine. Pyroxene dissolution and corrosion are indicated by sharp pointed alteration features on clinopyroxene in the Mars meteorite Nakhla, scaly features on orthopyroxene at the orthopyroxene-carbonate interface in the Allan Hills 84001 Mars meteorite, and angular sawtooth features on soil grains from the Phoenix landing site, all of which are similar or identical to common corrosion textures on weathered terrestrial pyroxene and related chain-silicate minerals. Primary-mineral corrosion occurs in Mars meteorites of a range of alteration ages, from ~3.9 Ga (~ Mid-Noachian; orthopyroxene corrosion and associated carbonate formation in ALH 84001), through ~670 Ma (~ Mid-Late Amazonian; clinopyroxene corrosion and diverse alteration minerals in nakhlites), and possibly quite recently (Late Amazonian; pre-terrestrial carbonate and sulfate in the ~170 Ma-old shergottite EET 79001). Primary-mineral removal of indeterminate but possibly quite recent age is also recorded from Mars-surface microscopic imagery, including euhedral olivine molds in weathered rinds on basaltic boulders at Gusev crater and possible pyroxene corrosion in unconsolidated granular material at the Phoenix landing site, preserved despite possible physical transport and abrasion processes. These occurrences of primary-mineral modification and destruction record aqueous alteration processes over a broad range of times in the paleoenvironmental history of Mars’ surface.

  1. The Effect of Temperature on OH in Olivine at 8 GPa

    NASA Astrophysics Data System (ADS)

    Withers, A. C.; Aubaud, C.; Hirschmann, M. M.

    2006-12-01

    To investigate the effects of oxygen fugacity and silica activity on H2O incorporation in mantle minerals, we have performed a series of experiments in the multi-anvil at 8 GPa and 1400-1600 °C. Starting materials consisted of bulk compositions similar in composition to a mantle mineral (olivine, clinopyroxene or garnet), to which was added 10 wt. % of a second phase, or mixture of phases, to buffer silica activity, and 5 wt.% H2O, which provided a flux for melting. Olivines of composition fo 90 were buffered in a SiO2 by either orthopyroxene or magnesiowüstite in the FeO-MgO-SiO2-H2O system, or clinopyroxene in the Na2O-FeO-CaO-MgO-MnO-Al2O3-Cr2O3-SiO2-TiO2- H2O system. A double AuPd capsule arrangement was used with a metal/oxide fO2 buffer between the two capsules. The electron microprobe was used to check for the presence of secondary phases and for elemental analysis, and SIMS was used for quantitative analysis of H2O. Water contents of olivines at 8 GPa and 1400 °C varied between 560 and 1080 ppm, while clinopyroxenes synthesised under similar conditions contained 2000 ppm H2O. Garnets synthesized without aSiO2 buffer at 1500 °C had 336 ppm H2O. With increasing temperature, water contents of olivines decreased to 327 ppm at 1600 °C. The water contents of olivines from this study at 1400-1600 °C are significantly lower than those previously reported for experiments at 1000-1200 °C, most likely due to dilution of the H2O component of the melt with increasing temperature. This observation highlights the necessity of taking into account the diminishing aH2O in the melt phase when extrapolating low temperature solubility measurements to mantle conditions. The high H2O content of clinopyroxene suggests that more water may in fact be stored in clinopyroxene than in olivine in the mantle overlying the transition zone, despite the lower relative abundance of clinopyroxene.

  2. Heterogeneity and O-16-Enrichments in Oxygen Isotope Ratios of Olivine from Chondrules in the Mokoia CV3 Chondrite

    NASA Technical Reports Server (NTRS)

    Jones, R. H.; Leshin, L. A.; Guan, Y.

    2002-01-01

    Two chondrules from Mokoia contain olivine in which oxygen isotopes are extremely heterogeneous, with some grains highly enriched in O-16. These data provide an important link between CAIs and chondrules. Additional information is contained in the original extended abstract.

  3. The Effect of Alkalis and Titanium on the Fe-Mg K(sub D) Between Olivine and Liquid

    NASA Technical Reports Server (NTRS)

    Xirouchakis, D.; Hirschmann, M. M.; Draper, D. S.

    2000-01-01

    Experimental evidence shows that compositional effects on Fe-Mg exchange between olivine and liquid cannot be overlooked. High contents of alkalis and/or titanium decrease K(sub D), in contrast to the weak positive pressure dependence.

  4. Olivine flotation and settling experiments on the join Mg2SiO4-Fe2SiO4

    NASA Technical Reports Server (NTRS)

    Herzberg, C. T.; Baker, M. B.; Wendlandt, R. F.

    1982-01-01

    Results are presented of a study of some unusual density relations between olivine and coexisting liquid in the system fosterite-fayalite. At 1 atmosphere pressure it is found that olivine floats on its coexisting liquid for intermediate compositions on this binary because of extreme partitioning of Fe into the melt phase. At 20 kilobars, the usual behavior of olivine settling is found to occur because the partitioning of Fe in the melt is reduced, aided possibly by the dissolution of CO2 in the melt from the use of a graphite container. It is determined that olivine flotation and settling are rapid in a time period of only a few hours because viscosities are slightly greater than that of paraffin oil at room temperature. Some adcumulate textures with good triple junction grain boundaries are found to be developed. Observations of differentiated magmatic systems suggest that the mechanisms by which magmas can differentiate vary considerably in the ultramafic to tholeiitic compositional range.

  5. An experimental study of trace element partitioning between olivine, orthopyroxene and melt in chondrules - Equilibrium values and kinetic effects

    NASA Technical Reports Server (NTRS)

    Kennedy, A. K.; Lofgren, G. E.; Wasserburg, G. J.

    1993-01-01

    Mineral/melt partition coefficients were measured using an ion microprobe for 32 elements in orthopyroxene and olivine in equilibrium and dynamic crystallization experiments on compositions corresponding to chondrules. The mineral/melt partition coefficients calculated from the measured concentrations for both olivine and orthopyroxene show very little change between equilibrium experiments and dynamic experiments with cooling rates of up to 100 C/h. The results provide a self-consistent set of partition coefficients that can be used in thermodynamic models of equilibrium and kinetic partitioning between olivine, orthopyroxene, and melt. These data can be used in models of partial melting and crystal fractionation in olivine- and orthopyroxene-rich systems, such as chondrules. The results may also be applicable to mantle peridotites, komatiitic and picritic lavas, and ultramafic intrusions.

  6. Origin of iron-rich olivine in the matrices of type 3 ordinary chondrites - an experimental study

    NASA Astrophysics Data System (ADS)

    Nagahara, H.; Kushiro, I.

    1987-10-01

    The reaction of metallic iron and enstatite, with and without forsterite and SiO2, is experimentally studied at temperatures between 1150 and 800 C in order to investigate the origin of iron-rich olivine in the matrices of type 3 chondrites. The composition of olivine is shown to become more iron-rich with increasing silica/enstatite ratio. Possible scenarios for the origin of this olivine include: (1) free silica having been present if the iron-rich olivine was formed by solid-state reactions under oxidizing conditions in the solar nebula; and (2) the reaction of silicon-rich gas with metallic iron having taken place under oxidizing conditions in the solar nebula.

  7. Temperature Dependence of Individual Absorptions Bands in Olivine: Implications for Inferring Compositions of Asteroid Surfaces from Spectra

    NASA Technical Reports Server (NTRS)

    Sunshine, J. M.; Hinrichs, J. L.; Lucey, P. G.

    2000-01-01

    The temperature variations of individual absorptions in olivine are modeled and found to narrow, move slightly in position, and change in relative strength as predicted by theory. These thermal changes may be confused with compositional differences.

  8. Petrography and classification of Ca, Al-rich and olivine-rich inclusions in the Allende CV3 chondrite

    NASA Technical Reports Server (NTRS)

    Kormacki, A. S.; Wood, J. A.

    1984-01-01

    The results of a detailed, systematic petrographic survey of Ca, Al-rich and olivine-rich inclusions in the Allende CV3 chondrite are reported, and a new classification system based on clearly defined and readily applied petrographic criteria is presented. Most Allende inclusions are aggregates containing one or more of three distinct constituents: (1) rimmed concentric objects enriched in Al- and Ti-rich oxide minerals and various amounts of Ca-rich silicates; (2) porous, 'fine-grained' chaotic material enriched in Ca-rich silicates, especially clinopyroxenes and garnets; and (3) porous, 'fine-grained', mafic inclusion matrix, enriched in olivine, pyroxene, and feldspathoids. Two texturally distinct varieties of inclusions consist primarily of inclusion matrix: unrimmed olivine aggregates and rimmed olivine aggregates. Ca, Al-rich inclusions are classified on the basis of the size and abundance of their constituent concentric objects. Some fundamental relationships among Allende inclusions that previusly have not been emphasized are discussed.

  9. Compositional and Microstructural Evolution of Olivine During Pulsed Laser Irradiation: Insights Based on a FIB/Field-Emission TEM Study

    NASA Astrophysics Data System (ADS)

    Christoffersen, R.; Loeffler, M. J.; Dukes, C. A.; Baragiola, R. A.

    2015-11-01

    Field-emission TEM shows multi-layer vapor and melt deposits produced on olivine by pulsed laser irradiation contain abundant nanophase metallic Fe and have some microstructural similarities to melt deposits in micrometeorite impact craters.

  10. Alteration of Al-rich inclusions inside amoeboid olivine aggregates in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Hashimoto, Akihiko; Grossman, Lawrence

    1987-01-01

    The primary phases of Al-rich inclusions in amoeboid olivine aggregates have undergone alteration reactions with the solar nebular gas. The simplest interpretation of the present observations is that melilite was the first primary phase to disappear with falling temperature, and was replaced by grossular + anorthite + feldspathoids, followed by fassaite; spinel was the last phase to be altered. Thermodynamic calculations suggest that Na-rich phlogopite could have formed at about 470 K and chlorite at about 328 K at a water fugacity of 0.000001, which is that of a gas of solar composition in this temperature range. The olivine around Al-rich inclusions is not serpentized, indicating the cessation of gas-solid equilibrium above 274 K.

  11. Strain Partitioning and Crystallographic Textures of Experimentally Deformed Olivine + Orthopyroxene Aggregates

    NASA Astrophysics Data System (ADS)

    Sundberg, M.; Cooper, R. F.

    2005-12-01

    The plastic deformation of polycrystalline rocks incorporates the grain matrix deformation of the individual grains (via chemical diffusion and/or dislocation propagation) acting in kinetic series with inter-grain sliding along grain- and phase-boundaries. In a polyphase aggregate where multiple types of interfaces exist, plastic deformation necessarily leads to strain partitioning and phase separation predicated on the relative effective viscosities of grain- and phase-boundaries. This segregation is sensitive both to lithology and stress, and manifests itself both in the grain-scale microstructures and in the lattice preferred orientations of the component phases. We have deformed fine-grained (~5 ?m) aggregates of Balsam Gap dunite + Bamble, Norway orthopyroxene in triaxial compression and in (nominally) simple shear to investigate textural development in polyphase mantle rocks. Constant-load triaxial compression tests were conducted at P=300 MPa, T=1200°C in a Paterson-type gas medium apparatus. Simple shear tests were conducted at P=1.6 GPa and T=1200°C in a Griggs apparatus using a molten-salt cell at strain rates of 10-5s-1 to 10-4s-1. Samples were dried for 12 h (CO:CO2 buffer at 950-1000°C) prior to sintering to ensure that these experiments were conducted in an anhydrous environment. No melt was produced during these experiments. Constant-load tests, conducted over the range of strain-rates used in the constant displacement-rate shear experiments, on a 50:50 mixture of olivine and orthopyroxene, reveal a stress exponent of 1.5±0.2. Similar experiments conducted on a 35:65 mixture of olivine and orthopyroxene reveal a stress exponent of 2.0±0.2. The fine grain size of the aggregates and the small stresses (<15 MPa) used in the creep tests would seem to preclude significant contribution of dislocation motion to the rheology. Samples composed of 35 vol% orthopyroxene deformed in shear at a constant strain-rate of 10-5s-1 develop a pronounced olivine lineation oriented ~35o antithetic to the shear plane. Samples of identical composition deformed at a shear strain-rate of 10-4s-1 do not display this behavior. Samples with greater than 50 vol% olivine do not display an olivine or orthopyroxene lineation regardless of strain-rate. Olivine LPOs created in our two-phase aggregates are not consistent with patterns found in experimentally deformed, pure olivine aggregates. In samples with 65 vol% olivine deformed to ?=2, the [100] axes align in the shear plane perpendicular to the shear direction, while the [010] planes rotate 10-20° below the shear direction. In aggregates composed of 50 vol% or more pyroxene deformed to similar strains, the [100] axis lineation is identical, however the [010] planes back-rotate 10-20° from the shear plane.

  12. THE IRRADIATION-INDUCED OLIVINE TO AMORPHOUS PYROXENE TRANSFORMATION PRESERVED IN AN INTERPLANETARY DUST PARTICLE

    SciTech Connect

    Rietmeijer, Frans J. M.

    2009-11-01

    Amorphization of crystalline olivine to glass with a pyroxene composition is well known from high-energy irradiation experiments. This report is on the first natural occurrence of this process preserved in a chondritic aggregate interplanetary dust particle. The Fe-rich olivine grain textures and compositions and the glass grain compositions delineate this transformation that yielded glass with Fe-rich pyroxene compositions. The average glass composition, (Mg, Fe){sub 3}Si{sub 2}O{sub 7}, is a serpentine-dehydroxylate with O/Si = 3.56 +- 0.25, (Mg+Fe)/Si = 1.53 +- 0.24, and Mg/(Mg+Fe) = 0.74 +- 0.1. These measured atomic ratios match the ratios that have been proposed for amorphous interstellar silicate grains very well, albeit the measured Mg/(Mg+Fe) ratio is lower than was proposed for amorphous interstellar silicate grains, Mg/(Mg+Fe) > 0.9.

  13. Magnetic petrology of eastern North America diabases. I - Olivine-normative dikes from western South Carolina

    NASA Technical Reports Server (NTRS)

    Warner, Richard D.; Wasilewski, Peter J.

    1990-01-01

    The oxide mineralogy and the magnetic behavior of 15 olivine-normative samples obtained from South-Caroline diabase dikes were investigated using electron microprobe and SEM analyses and measurements of natural remanence magnetization (NRM), saturation isothermal remanence magnetization (SIRM), and anhysteritic remanence magnetization. It was found that chromite (which for these olivine-normative diabases is a sensitive petrologic indicator) constitutes up to 0.5 vol pct and that its abundance and composition correlate with bulk rock Cr. Microscopic analyses showed that titanomagnetite compositions were mostly between 0.4 and 0.55. The values of NRM and the NRM/SIRM ratios varied between 4 and 0.01 A sq m/kg and 0.0019 and 0.032, respectively. These properties inversely correlate with Cr content and demonstrably contrast Cr-rich and Cr-poor samples.

  14. Ar-Ar and Rb-Sr Ages of the Tissint Olivine-phyric Martian Shergottite

    NASA Technical Reports Server (NTRS)

    Park, J.; Herzog, G. F.; Nyquist, L. E.; Shih, C.-Y.; Turin, B.; Lindsay, F. N.; Delaney, J. S.; Swisher, C. C., III; Agee, C.

    2013-01-01

    The fifth martian meteorite fall, Tissint, is an olivine-phyric shergottite that contains olivine macrocrysts (approximately 1.5 mm) [1]. [2] reported the Sm-Nd age of Tissint as 596 plus or minus 23 Ma along with Rb-Sr data that defined no isochron. [3] reported Lu-Hf and Sm-Nd ages of 583 plus or minus 86 Ma and 616 plus or minus 67 Ma, respectively. The cosmic-ray exposure ages of Tissint are 1.10 plus or minus 0.15 Ma based on 10Be [4], and 1.0-1.1 Ma, based on 3He, 21Ne, and 38Ar [5,6].We report Ar-Ar ages and Rb-Sr data.

  15. Origins and Distribution of Chondritic Olivine Inferred from Wild 2 and Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Frank, D. R.; Zolensky, M. E.

    2014-01-01

    To date, only 180 particle impact tracks from Wild 2 have been extracted from the Stardust aerogel collector and even fewer have been thoroughly characterized. In order to provide a cohesive compositional dataset that can be compared to the meteorite record, we have made both major and minor element analyses (TEM/EDXS) of olivine and low-Ca pyroxene for 39 particles harvested from 26 tracks. However, the dearth of equivalent analyses for these phases in chondrite matrix hinders their comparison to the Wild 2 samples. To properly permit comparison of chondritic olivine and pyroxene to the Wild 2 samples, we have also provided a large, comprehensive EPMA dataset (greater than10(exp 3) analyses) of analogous grains (5-30 micrometers) isolated in L/LL3.0-4, CI, CM, CR, CH, CO, CV, Acfer 094, EH3, EL6, and Kakangari matrix

  16. Partition coefficients for Al, Ca, Ti, Cr, and Ni in olivine obtained by melting experiment on an LL6 chondrite

    NASA Technical Reports Server (NTRS)

    Miyamoto, M.; Mikouchi, T.; Mckay, G. A.

    1994-01-01

    We report the partition coefficients for Ca, Al, Ti, Cr, and Ni in olivine obtained through a series of melting experiments on an LL6 chondrite under varying conditions of temperature and oxygen fugacity. It is necessary to examine the variation of partition coefficients up to extremely reducing conditions in order to study meteoritic olivines. For Ca, Al, and Cr, the partition coefficients tend to decrease as temperature increases, but do not change even under extremely reducing conditions.

  17. Characterization of olivine fabrics and mylonite in the presence of fluid and implications for seismic anisotropy and shear localization

    NASA Astrophysics Data System (ADS)

    Jung, Sejin; Jung, Haemyeong; Austrheim, Håkon

    2015-04-01

    The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies shear zones and pseudotachylytes. To understand how a superimposed tectonic event may influence olivine fabric and change seismic anisotropy, two lenses of spinel lherzolite were studied by SEM and EBSD techniques. The granulite foliation of the surrounding anorthosite complex is displayed in ultramafic lenses as a modal variation in olivine, pyroxenes and spinel, and the Caledonian eclogite-facies structure in the surrounding anorthosite gabbro is represented by thin (<1 cm) garnet-bearing ultramylonite zones. The olivine fabrics in the spinel bearing assemblage were E-type and B-type and a combination of A- and B-type LPOs. There was a change in olivine fabric from a combination of A- and B-type LPOs in the spinel bearing assemblage to B- and E-type LPOs in the garnet lherzolite mylonite zones. FTIR analyses reveal that the water content of olivine in mylonite is much higher (~600 ppm H/Si) than that in spinel lherzolite (~350 ppm H/Si), indicating that water caused the difference in olivine fabric. Fabric strength of olivine gets weaker as the grain size reduced, and as a result calculated seismic properties for the two deformation stages reveal that P- and S-velocity anisotropies are significantly weaker in the mylonite. Microtextures and LPO data indicate that the deformation mechanism changed from dominant dislocation creep in spinel lherzolite to dislocation creep accompanied by grain-boundary sliding in mylonite. Shear localization in the mylonite appears to be originated from the grain size reduction through (1) enhanced dynamic recrystallization of olivine in the presence of water and (2) Zener pinning of clinopyroxene, or (3) by ultracommunition during the pseudotachylyte stage.

  18. Characterization of olivine fabrics and mylonite in the presence of fluid and implications for seismic anisotropy and shear localization

    NASA Astrophysics Data System (ADS)

    Jung, Sejin; Jung, Haemyeong; Austrheim, Håkon

    2014-12-01

    The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies shear zones and pseudotachylytes. To understand how a superimposed tectonic event may influence olivine fabric and change seismic anisotropy, two lenses of spinel lherzolite were studied by scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD) techniques. The granulite foliation of the surrounding anorthosite complex is displayed in ultramafic lenses as a modal variation in olivine, pyroxenes, and spinel, and the Caledonian eclogite-facies structure in the surrounding anorthosite gabbro is represented by thin (<1 cm) garnet-bearing ultramylonite zones. The olivine fabrics in the spinel bearing assemblage were E-type and B-type and a combination of A- and B-type lattice preferred orientations (LPOs). There was a change in olivine fabric from a combination of A- and B-type LPOs in the spinel bearing assemblage to B- and E-type LPOs in the garnet lherzolite mylonite zones. Fourier transform infrared (FTIR) spectroscopy analyses reveal that the water content of olivine in mylonite is much higher (approximately 600 ppm H/Si) than that in spinel lherzolite (approximately 350 ppm H/Si), indicating that water caused the difference in olivine fabric. Fabric strength of olivine gets weaker as the grain size reduced, and as a result, calculated seismic properties for the two deformation stages reveal that P- and S-velocity anisotropies are significantly weaker in the mylonite. Microtextures and LPO data indicate that the deformation mechanism changed from dominant dislocation creep in spinel lherzolite to dislocation creep accompanied by grain-boundary sliding in mylonite. Shear localization in the mylonite appears to be originated from the grain size reduction through (1) enhanced dynamic recrystallization of olivine in the presence of water and (2) Zener pinning of clinopyroxene or (3) by ultracomminution during the pseudotachylyte stage.

  19. Natural Fumarolic Alteration of Fluorapatite, Olivine, and Basaltic Glass, and Implications for Habitable Environments on Mars

    PubMed Central

    Tschauner, Oliver

    2013-01-01

    Abstract Fumaroles represent a very important potential habitat on Mars because they contain water and nutrients. Global deposition of volcanic sulfate aerosols may also have been an important soil-forming process affecting large areas of Mars. Here we identify alteration from the Senator fumarole, northwest Nevada, USA, and in low-temperature environments near the fumarole to help interpret fumarolic and acid vapor alteration of rocks and soils on Mars. We analyzed soil samples and fluorapatite, olivine, and basaltic glass placed at and near the fumarole in in situ mineral alteration experiments designed to measure weathering under natural field conditions. Using synchrotron X-ray diffraction, we clearly observe hydroxyl-carbonate-bearing fluorapatite as a fumarolic alteration product of the original material, fluorapatite. The composition of apatites as well as secondary phosphates has been previously used to infer magmatic conditions as well as fumarolic conditions on Mars. To our knowledge, the observations reported here represent the first documented instance of formation of hydroxyl-carbonate-bearing apatite from fluorapatite in a field experiment. Retreat of olivine surfaces, as well as abundant NH4-containing minerals, was also characteristic of fumarolic alteration. In contrast, alteration in the nearby low-temperature environment resulted in formation of large pits on olivine surfaces, which were clearly distinguishable from the fumarolic alteration. Raman signatures of some fumarolically impacted surfaces are consistent with detection of the biological molecules chlorophyll and scytenomin, potentially useful biosignatures. Observations of altered minerals on Mars may therefore help identify the environment of formation and understand the aqueous history and potential habitability of that planet. Key Words: Fumaroles—Mars—Olivine—Acidophile—Geothermal—Search for life (biosignatures)—Synchrotron X-ray diffraction. Astrobiology 13, 1049–1064. PMID:24283927

  20. Experimental Deformation of Olivine Single Crystals at Mantle Pressures and Temperatures

    SciTech Connect

    Raterron, P.; Amiguet, E; Chen, J; Li, L; Cordier, P

    2008-01-01

    Deformation experiments were carried out in a deformation-DIA high-pressure apparatus (D-DIA) on oriented San Carlos olivine single crystals, at pressure (P) ranging from 3.5 to 8.5 GPa, temperature (T) from 1373 to 1673 K, and in poor water condition. Oxygen fugacity (fO2) was maintained within the olivine stability field and contact with enstatite powder ensured an orthopyroxene activity aopx = 1. Two compression directions were tested, promoting either [1 0 0] slip alone or [0 0 1] slip alone in (0 1 0) crystallographic plane, here called, respectively, a-slip and c-slip. Constant applied stress (s) and specimen strain rates ({bar {var_epsilon}}) were monitored in situ using time-resolved X-ray synchrotron diffraction and radiography, respectively. Transmission electron microscopy (TEM) investigation of run products revealed that dislocation creep was responsible for sample deformation. Comparison of the obtained high-P deformation data with the data obtained at room-P by Bai et al. [Bai, Q., Mackwell, S.L., Kohlstedt D.L., 1991, High-temperature creep of olivine single crystals. 1. Mechanical results for buffered samples, Journal of Geophysical Research, 96, 2441-2463] - on identical materials deformed at comparable T-sefO2-aopx conditions - allowed quantifying the P effect on a-slip and c-slip rheological laws. A slip transition with increasing pressure, from dominant a-slip to dominant c-slip, is documented. a-slip appears sensitive to pressure, which translates into the high activation volume V*{sub a} = 12 {+-} 4 cm{sup 3}/mol in the corresponding rheological law, while pressure has little effect on c-slip with V*{sub c} = 3 {+-} 4 cm{sup 3}/mol. These results may explain the discrepancy between olivine low-P and high-P deformation data which has been debated in the literature for more than a decade.

  1. Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

    USGS Publications Warehouse

    Teng, F.-Z.; Dauphas, N.; Helz, R.T.; Gao, S.; Huang, S.

    2011-01-01

    Diffusion plays an important role in Earth sciences to estimate the timescales of geological processes such as erosion, sediment burial, and magma cooling. In igneous systems, these diffusive processes are recorded in the form of crystal zoning. However, meaningful interpretation of these signatures is often hampered by the fact that they cannot be unambiguously ascribed to a single process (e.g., magmatic fractionation, diffusion limited transport in the crystal or in the liquid). Here we show that Mg and Fe isotope fractionations in olivine crystals can be used to trace diffusive processes in magmatic systems. Over sixty olivine fragments from Hawaiian basalts show isotopically fractionated Mg and Fe relative to basalts worldwide, with up to 0.4??? variation in 26Mg/24Mg ratios and 1.6??? variation in 56Fe/54Fe ratios. The linearly and negatively correlated Mg and Fe isotopic compositions [i.e., ??56Fe=(??3.3??0.3)????26Mg], co-variations of Mg and Fe isotopic compositions with Fe/Mg ratios of olivine fragments, and modeling results based on Mg and Fe elemental profiles demonstrate the coupled Mg and Fe isotope fractionation to be a manifestation of Mg-Fe inter-diffusion in zoned olivines during magmatic differentiation. This characteristic can be used to constrain the nature of mineral zoning in igneous and metamorphic rocks, and hence determine the residence times of crystals in magmas, the composition of primary melts, and the duration of metamorphic events. With improvements in methodology, in situ isotope mapping will become an essential tool of petrology to identify diffusion in crystals. ?? 2011 Elsevier B.V.

  2. On high-temperature formation of iron-rich olivine in the early solar system

    NASA Technical Reports Server (NTRS)

    Dorofeyeva, V. A.; Makalkin, A. B.; Vityazev, A. V.

    1993-01-01

    A kinetic restriction on the formation of fayalite-rich olivine in equilibrium with the cooling solar-composition gas appears to exist at the low temperature of approximately 500 K. We offer a high-temperature formation mechanism (different from simple condensation) which operates at high hydrogen depletion (up to 300 times) relative to solar abundance. We show how the necessary depletion rate decreases with temperature (thermodynamical equilibrium is suggested). The consequences for planet formation are considered.

  3. High-silica glass inclusions in olivine of Luna-24 samples

    NASA Technical Reports Server (NTRS)

    Roedder, E.; Weiblen, P. W.

    1977-01-01

    Optical examination of nine polished grain mounts of Luna-24 drill-core material (0.09-0.50 mm size) revealed melt inclusions in olivine crystals. Two inclusions consist of clear glass with exceptionally high Si, yet contain no visible daughter minerals and have had no reaction effects with the olivine walls. Their compositions (one has SiO2 93.8, Al2O3 1.51, FeO 2.32, MgO 1.61, CaO 0.06, Na2O less than 0.05, K2O 0.11, total 99.41%; the other is similar) are unique and quite unlike the high-Si high-K melt of granitic composition that is found as inclusions in late-stage minerals of these (and the Apollo) samples, from silicate liquid immiscibility. The host olivines are Fo73 and Fo51. The origin of the melt in the inclusions and the lack of reaction effects are perplexing unsolved problems.

  4. Polycrystalline olivine rheology in dislocation creep: Revisiting experimental data to 8.1 GPa

    NASA Astrophysics Data System (ADS)

    Bollinger, Caroline; Raterron, Paul; Cordier, Patrick; Merkel, Sébastien

    2014-03-01

    The rheology of polycristalline San Carlos olivine is investigated on synchrotron beamline in the Deformation-DIA (D-DIA) at pressure (P) between 3.8 and 8.1 GPa, temperature (T) within 1373-1673 K, and at steady-state strain rates ranging from 1.1 × 10-5 to 5.8 × 10-5 s-1. Transmission electron microscopy (TEM) on run products reveals microstructures characteristic of the so-called “dislocation creep regime”. Fourier transform infrared (FTIR) measurements reveal hydroxyl concentrations within 153-1526 ppm H/Si (Paterson’s calibration), indicating ‘wet’ conditions of deformation. Analysis of our data together with previously published ‘wet’ deformation data obtained at room and high P, assuming a stress exponent n = 3.5 in classical power law, results in a linear dependence of the activation enthalpy with P, i.e., in an activation volume of V? = 12.8 ± 5 cm3 mol-1. This value of V? is also consistent with a global dataset including ‘wet’ data and ‘dry’ published deformation data for olivine aggregates. We thus conclude that, up to 8 GPa, the effect of P on ‘dry’ and ‘wet’ olivine dislocation creep is consistent with V? = 12.8 ± 5 cm3 mol-1.

  5. Comparison of domestic olivine and European magnesite for electrically charged thermal energy storage

    SciTech Connect

    Laster, W.R.; Gay, B.M.; Palmour, H.; Schoenhals, R.J.

    1982-01-01

    Electrically charged thermal energy storage (TES) heaters employing high heat capacity ceramic refractories for sensible heat storage have been in use in Europe for several years. With these devices, low cost off-peak electrical energy is stored by heating a storage core composed of ceramic material to approximately 800/sup 0/C. During the peak period, no electrical energy is used as the building heating needs are supplied by extracting the stored energy from the core by forced air circulation. The recent increase in use of off-peak TES units in the U.S. has led to the search for a domestic supply of high heat capacity ceramic refractory material. North Carolina's extensive but underutilized supply of refractory grade olivine has been proposed as a source of storage material for these units. In this paper the suitability of North Carolina olivine for heat storage applications is assessed by comparing its thermal performance with that of European materials. Using the method of ASHRAE Standard 94.2, the thermal performance of two commercially available room-size TES units was determined experimentally with two different storage materials, North Carolina olivine and German magnesite. Comparisons are made and conclusions are drawn.

  6. Trace elements of olivine in silicate inclusions of IAB iron meteorites reflecting low-temperature history

    NASA Astrophysics Data System (ADS)

    Zipfel, J.; Weinbruch, S.; Specht, S.; Palme, H.

    1994-07-01

    IAB iron meteorites with silicate inclusions may have formed at the core-mantle boundary of planetary bodies. Important constraints on the thermal evolution and the size of these bodies are given by cooling rates obtained from these meteorites. Recent metallographic cooling rates determined in metal grains enclosed in silicates of IAB irons are between 30 and 70 C/m.y. An independent method for obtaining cooling rates of IAB silicates inclusions was suggested by Kohler (1991). The Ca contents of olivines are zoned from core to rim reflecting cooling from about 650 to 500 C, at similar temperatures as kamacite-taenite exsolution occurs. Calcium zoning of ol was observed in Landes, Caddo County, Woodbine, and Persimmon Creek (recent ion microprobe data). In addition, the central Ca content of olivine grains of different IAB meteorites should also reflect cooling rates. Olivine core compositions in silicates of several IAB meteorites, e.g., Persimmon Creek (PC), El Taco (ET), Woodbine (WB), Landes (LA), Caddo County (CC), and Copiapo (COP) were determined with the electron microprobe. Results of the electron microporbe study are discussed. The use of Ca core contents and Ca profiles as indicators of low-temperature cooling rates requires further work. Nickel in ol may provide additional constraints on the thermal histories.

  7. Work function measurements of olivine: Implication to photoemission charging properties in planetary environments

    NASA Astrophysics Data System (ADS)

    Gan, Hong; Li, Xiongyao; Wei, Guangfei; Wang, Shijie

    2015-12-01

    For understanding the ubiquitous photoemission charging of solid surface in planetary environments, it is important to characterize the photoemission charging properties of silicate minerals such as the work function. In this study, we measured the work function of olivine mineral based on the measurements of contact potential difference by using an ultrahigh vacuum Kelvin probe force microscopy. Our results showed that work function on olivine mineral surface is mainly affected by surface morphology and crystal orientation and that the variation range of work function is 7.3-8.5 eV. It implicates that photoemission of the olivine mineral occurs under the X-ray and solar ultraviolet irradiation with wavelength of <171 nm. Consequently, it is possible to form electrostatic field of +(5-10) V on the sunlit planet, moon or asteroid surfaces due to dust photoemission charging, which even induces the migration of dust grains and the formation of dust-plasma atmosphere. Those are important problems worried to be solved for future lunar missions. Additionally, our work can help to instruct the dust mitigation technology and the electrostatic beneficiation in future space missions.

  8. Extracting Olivine (Fo-Fa) Compositions from Raman Spectral Peak Positions

    NASA Technical Reports Server (NTRS)

    Kuebler, K.; Jolliff, B. J.; Wang, Alian; Haskin, L. A.

    2005-01-01

    Olivine and pyroxene are two major basaltic minerals that have been identified at Gusev Crater and Meridiani Planum by the Mars Exploration Rovers. Full petrologic characterization of a sample (rock or soil), however, requires determining the range of mineral compositions, extent of zoning, range of grain sizes, mineral associations, presence of xenocrysts, etc. Information of this sort will aid the interpretation of sample crystallization and differentiation histories and help discriminate between lithologies. In Raman spectroscopic experiments, minerals are identified by their spectral patterns and mineral compositions can be inferred from the peak positions. Instruments currently in use or slated for impending surface exploration missions provide only average elemental compositions for relatively large rock or soil targets or bulk mineral analysis. No techniques currently in use or scheduled for flight can characterize both structure and composition of individual mineral grains, in-situ, like the Mars Microbeam Raman Spectrometer (MMRS). The MMRS is designed to take 100 spectra along a 1 cm linear traverse on the surface of a sample, with contributions from one or a few mineral phases per spectrum. We presented a method to extract structural and compositional information from the Raman spectra of quadrilateral pyroxenes. The pyroxene calibration was applied to a Raman spectroscopic study of Martian meteorite EETA79001 along with a preliminary olivine calibration, where we demonstrated the capability to discriminate related lithologies using Raman point counts. This paper presents an improved olivine calibration that will further aid sample characterization and the study of alteration processes.

  9. Mg Fe partitioning between olivine and ultramafic melts at high pressures

    NASA Astrophysics Data System (ADS)

    Mibe, Kenji; Fujii, Toshitsugu; Yasuda, Atsushi; Ono, Shigeaki

    2006-02-01

    Precise determination of the partitioning of Mg and Fe 2+ between olivine and ultramafic melt has been made at pressures from 5 to 13 GPa using a MA-8 type multi-anvil high-pressure apparatus (PREM) installed at Earthquake Research Institute, University of Tokyo. A very short rhenium capsule (<100 ?m sample thickness) was adopted to minimize temperature variation within the sample container. Synthetic gels with the composition of the upper mantle peridotite were used as starting materials to promote the homogeneity. Analyses of quenched melts and coexisting olivines were made with an electron probe microanalyzer. The obtained partition coefficient, KD [=(FeO/MgO) ol/(FeO/MgO) melt], decreases from 0.35 to 0.25 with increasing pressure from 5 to 13 GPa, suggesting a negative correlation between pressure and KD above 5 GPa. Our result is consistent with a parabolic relationship between KD and degree of polymerization (NBO/T) of melts reported by previous studies at lower pressures. The negative correlation between pressure and KD suggests that olivine crystallizing in a magma ocean becomes more Mg-rich with depth and that primary magmas generated in the upper mantle become more Fe-rich with depth than previously estimated.

  10. Modal abundances of pyroxene, olivine, and mesostasis in nakhlites: Heterogeneity, variation, and implications for nakhlite emplacement

    NASA Astrophysics Data System (ADS)

    Corrigan, Catherine M.; Velbel, Michael A.; Vicenzi, Edward P.

    2015-09-01

    Nakhlites, clinopyroxenite meteorites from Mars, share common crystallization and ejection ages, suggesting that they might have been ejected from the same place on Mars by the same ejection event (impact) and are different samples of the same thick volcanic flow unit or shallow sill. Mean modal abundances and abundance ranges of pyroxene, olivine, and mesostasis vary widely among different thin-sections of an individual nakhlite. Lithologic heterogeneity is the main factor contributing to the observed modal-abundance variations measured in thin-sections prepared from different fragments of the same stone. Two groups of nakhlites are distinguished from one another by which major constituent varies the least and the abundance of that constituent. The group consisting of Nakhla, Lafayette, Governador Valadares, and the Yamato nakhlite pairing group is characterized by low modal mesostasis and pyroxene-olivine covariance, whereas the group consisting of the Miller Range nakhlite pairing group and Northwest Africa 5790 is characterized by low modal olivine and pyroxene-mesostasis covariance. These two groups sample the slowest-cooled interior portion and the chilled margin, respectively, of the nakhlite emplacement body as presently understood, and appear to be also related to recently proposed nakhlite groups independently established using compositional rather than petrographic observations. Phenocryst modal abundances vary with inferred depth in the nakhlite igneous body in a manner consistent with solidification of the nakhlite stack from dynamically sorted phenocryst-rich magmatic crystal-liquid mush.

  11. Helium solubility in olivine and implications for high 3He/4He in ocean island basalts.

    PubMed

    Parman, Stephen W; Kurz, Mark D; Hart, Stanley R; Grove, Timothy L

    2005-10-20

    High 3He/4He ratios found in ocean island basalts are the main evidence for the existence of an undegassed mantle reservoir. However, models of helium isotope evolution depend critically on the chemical behaviour of helium during mantle melting. It is generally assumed that helium is strongly enriched in mantle melts relative to uranium and thorium, yet estimates of helium partitioning in mantle minerals have produced conflicting results. Here we present experimental measurements of helium solubility in olivine at atmospheric pressure. Natural and synthetic olivines were equilibrated with a 50% helium atmosphere and analysed by crushing in vacuo followed by melting, and yield a minimum olivine-melt partition coefficient of 0.0025 +/- 0.0005 (s.d.) and a maximum of 0.0060 +/- 0.0007 (s.d.). The results indicate that helium might be more compatible than uranium and thorium during mantle melting and that high 3He/4He ratios can be preserved in depleted residues of melting. A depleted source for high 3He/4He ocean island basalts would resolve the apparent discrepancy in the relative helium concentrations of ocean island and mid-ocean-ridge basalts. PMID:16237441

  12. Pressure-induced structural modifications in Mg2GeO4-olivine: A Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Reynard, Bruno; Petit, Pierre-Emmanuel; Guyot, François; Gillet, Philippe

    1994-05-01

    Raman spectra of Mg2GeO4-olivine were obtained from ambient pressure up to 34 GPa at ambient temperature. Under quasi-hydrostatic pressure conditions, the following modifications in the Raman spectra occur as pressure increases: 1) near 11 GPa, two sharp extra bands appear in the 600 700 cm-1 frequency range, and increase in intensity with respect to the olivine bands; 2) above 22 GPa, these two bands become very intense, and the number, position and relative intensity of the other vibrational bands drastically change; 3) the intensity of sharp bands progressively decreases above 25 GPa. The transformation occurs at lower pressures under non-hydrostatic conditions. During decompression to atmospheric pressure, the high-pressure phase partially reverts to olivine. These observations can be interpreted as the progressive metastable transformation from the olivine structure to a crystalline phase with four-fold coordinated Ge, in which the GeO4 tetrahedra are polymerized. We propose that the metastable high-pressure phase is a structurally disordered spinelloid close to the hypothethical ?- or ?*-phase, and forms by a shear mechanism assisted by the development of a dynamical instability in the olivine structure. Implications for the transformations undergone by olivines under far-from-equilibrium conditions (e.g. in subducting lithospheric slabs and in shocks) are discussed.

  13. Laboratory Simulation of Space Weathering: ESR Measurements of Nanophase Metallic Iron in Laser-irradiated Olivine and Pyroxene Samples

    NASA Technical Reports Server (NTRS)

    Kurahashi, E.; Yamanaka, C.; Nakamura, K.; Sasaki, S.

    2003-01-01

    S-type asteroids are believed to be parent bodies of ordinary chondrites. Although both S-type asteroids and ordinary chondrites contain the same mineral assemblage, mainly olivine and pyroxene, the reflectance spectra of the asteroids exhibit more overall depletion (darkening) and reddening, and more weakening of absorption bands relative to the meteorites. This spectral mismatch is explained by space weathering process, where high-velocity dust particle impacts should change the optical properties of the uppermost regolith surface of asteroids. In order to simulate the space weathering, we irradiated nanosecond pulse laser beam onto pellet samples of olivine (8.97wt% FeO) and pyroxene (enstatite: 9.88wt% FeO, hypersthene: 16.70wt%). We got spectral changes in our samples similar to that by space weathering on asteroids and confirmed nanophase alpha-metallic iron particles, which were theoretically predicted, not only on olivine but also on pyroxene samples by Transmission Electron Microscopy (TEM). Nanophase metallic iron particles were widely scattered throughout the amorphous rims developed along the olivine grains, whereas they were embedded in aggregates of amorphous in enstatite samples. Recently, we also measured laser-irradiated samples by ESR (Electron Spin Resonance). Strong ESR signals, characteristic to nanophase iron particles, are observed on irradiated olivine samples. In this paper, we report the quantities of nanophase metallic iron particles in pyroxene samples by ESR observations in addition to olivine samples.

  14. Recycling bacteria for the synthesis of LiMPO4 (M = Fe, Mn) nanostructures for high-power lithium batteries.

    PubMed

    Zhou, Yanping; Yang, Dan; Zeng, Yi; Zhou, Yan; Ng, Wun Jern; Yan, Qingyu; Fong, Eileen

    2014-10-15

    In this work, a novel waste-to-resource strategy to convert waste bacteria into a useful class of cathode materials, lithium metal phosphate (LiMPO4; M = Fe, Mn), is presented. Escherichia coli (E. coli) bacteria used for removing phosphorus contamination from wastewater are harvested and used as precursors for the synthesis of LiMPO4. After annealing, LiFePO4 and LiMnPO4 nanoparticles with dimensions around 20 nm are obtained. These particles are found to be enveloped in a carbon layer with a thickness around 3-5 nm, generated through the decomposition of the organic matter from the bacterial cell cytoplasm. The battery performance for the LiFePO4 is evaluated. A high discharge capacity of 140 mAh g(-1) at 0.1 C with a flat plateau located at around 3.5 V is obtained. In addition, the synthesized particles display excellent stability and rate capabilities. Even under a high C rate of 10 C, a stable discharge capacity of 75.4 mAh g(-1) can still be achieved. PMID:24930375

  15. Thermal analysis of large-capacity LiFePO4 power batteries for electric vehicles

    NASA Astrophysics Data System (ADS)

    Lin, Chunjing; Xu, Sichuan; Li, Zhao; Li, Bin; Chang, Guofeng; Liu, Jinling

    2015-10-01

    Excellent design of a thermal management system requires good understanding of the thermal behaviors of power batteries. In this study, the electrochemical and heat performances of a prismatic 40 Ah C/LiFePO4 battery are investigated with a focus on the influence of temperature on cell capacity in a mixed charge-discharge cycle. In addition, the heat generation and energy efficiency of a battery are determined during charge and discharge at different current rates. The experimental results indicate that in certain temperature ranges, both the charging and discharging capacities increase significantly as the temperature increases. In addition, the energy efficiency reaches more than 95% when the battery runs at a current rate of 0.33 C-2 C and temperature of 25-45 °C. A thermal mathematical model based on experimentally obtained internal resistances and entropy coefficients is developed. Using this model, the increase in the battery temperature is simulated based on specific heat values that are measured experimentally and calculated theoretically. The results from the simulation indicate that the temperature increase agrees well with the experimental values, the measured specific heat provides better results than the calculated specific heat and the heat generated decreases as the temperature increases.

  16. TEM Study of Fracturing in Spherical and Plate-like LiFePO4Particles

    SciTech Connect

    Gabrisch, H.; Wilcox, J.; Doeff, M.M.

    2007-12-20

    An investigation of fracturing in LiFePO{sub 4} particles as a function of the particle morphology and history is presented. Two types of samples, one subjected to electrochemical cycling and another to chemical delithiation are compared. We observe the formation of micro fractures parallel to low indexed lattice planes in both samples. The fracture surfaces are predominantly parallel to (100) planes in the chemically delithiated powder and (100) and (010) planes in the electrochemically cycled powder. A consideration of the threshold stresses for dislocation glide shows that particle geometry plays an important role in the observed behavior.

  17. A high precision EPMA data of olivine: comparison with LA ICP-MS

    NASA Astrophysics Data System (ADS)

    Batanova, V. G.; Sobolev, A. V.; Kuzmin, D.

    2013-12-01

    Composition of olivine provides critical information on the composition and origin of primary mantle derived melts and their sources. Especially informative are minor and trace elements Ni, Mn, Ca, Al, Cr, Co, Ti, Zn, P, Na [1, 2], which being in the concentration range over 10 ppm are assessable by EPMA. The analytical protocol built up on new JEOL JXA 8230 EPMA in ISTerre, UJF, Grenoble, France. Facility has tungsten source gun, is equipped by five WDS and one SDD EDS and placed in the environment with controlled temperature (22+/-0.3 degrees C) and humidity (50+/-3%). The analytical conditions are the following: acceleration voltage 25kV, 900 nA beam current, WDS recording for trace elements (Ni, Mn, Ca, Al, Cr, Co, Ti, Zn, P, Na) and EDS recording for Si, Mg, Fe, total counting time 12 minutes, ZAF correction. Instrumental drift during analytical sessions is monitored by repeated measurements of olivine standards. For trace elements this protocol yields detection limits from 3 to 10 ppm and average precision of individual analysis of 10 ppm (2 standard errors). For Fo of olivine precision is 300 ppm (2 standard errors). Comparison of EPMA and LA ICP-MS data for the large range of olivine compositions suggests that accuracy of EPMA is similar to precision noted above. For elements with concentration over 100 ppm the obtained EPMA precision and accuracy are better than these of LA ICP-MS. For the concentration of elements between 50-100 ppm both methods show similar precision and accuracy; and for concentration between 10-50 ppm LA ICP-MS yields better precision and accuracy. Spatial resolution of EPMA, however, is significantly better: 3-5 micrometres compared to 30-50 for LA ICP-MS. This makes our new EPMA protocol of great advantage for measurement of zoned or small olivine grains. [1] Sobolev et al., 2007. Science 316 (5823), p.412-417. [2] De Hoog et al., 2010. Chemical Geology 270, p. 196-2015

  18. Anisotropic lattice thermal diffusivity in olivines and pyroxenes to high temperatures

    NASA Astrophysics Data System (ADS)

    Harrell, Michael Damian

    The anisotropic lattice thermal diffusivity of three olivines (Fo 0, Fo78, and Fo91), one orthopyroxene (En 91), and one clinopyroxene (Di72He9Jd3Cr 3Ts12) have been measured via impulsive stimulated light scattering, permitting the calculation of their lattice thermal diffusivity tensors to high temperatures. For Fo0 olivine, measurements extend from room temperature to 600°C, for Fo78 to 900°C, and for Fo91 to 1000°C, all in steps of 100°C. The orthopyroxene also was taken in steps to 1000°C, while the clinopyroxene was measured at room temperature. A limited set of room-temperature measurements to 5 GPa on a fourth olivine (Fo89) is also included. Diffusivities have been combined with calculations of density and specific heat to determine the lattice thermal conductivity tensors. An earlier theory that explains the observed behavior in terms of a positive lower bound on the phonon mean free path is discussed, and the data are used to constrain a model of thermal conductivity at high temperature. The relative contributions of optic and acoustic modes are evaluated from analysis of published dispersion curves. Five conclusions are reached: First, the anisotropy of lattice thermal conductivity remains essentially unchanged over the observed range of temperatures, indicating that anisotropy remains significant under upper-mantle conditions, and, in regions displaying preferred alignment, may account for observed lateral variations in the geotherm. Second, thermal conductivity departs significantly from earlier predictions of its temperature dependence; this may be understood in terms of a phonon mean free path that cannot diminish below 1.75 times the mean interatomic spacing. Third, for olivine, the optic modes have group velocities that are approximately one-third those of the acoustic modes, and do not dominate lattice conduction despite their greater number. Fourth, impurity scattering is significant along the olivine Fe-Mg solid solution series, but is not appreciable near the endpoints and therefore likely does not play a major role in the upper mantle. Fifth, the historic underestimation of lattice thermal conductivity at temperature has led to an overestimation of radiative conductivity; radiative transport, although significant, plays an even smaller role in the upper mantle than has heretofore been assumed.

  19. Elasticity of Hydrous Olivine Polymorphs: Implications for Seismic Structure of the Transition Zone

    NASA Astrophysics Data System (ADS)

    Duffy, T. S.; Mao, Z.; Jacobsen, S. D.; Jiang, F.; Smyth, J. R.; Holl, C. M.; Frost, D. J.

    2007-12-01

    The presence of water in the upper mantle and transition zone has the potential to explain various phenomena such as shear velocity anomalies or uplift and broadening of the 410-km discontinuity. The presence of H2O in the transition zone has also been frequently invoked to reconcile laboratory elasticity data on olivine polymorphs with seismic data for the amplitude of the 410-km discontinuity (Li et al., 2001; Chambers et al., 2005). Recently, we have measured the single-crystal elastic properties of hydrous olivine (Jacobsen et al., 2006) and a suite of hydrous wadsleyites (Mao et al., 2007a) at ambient conditions and one hydrous wadsleyite composition (0.84 wt% H2O) up to 12 GPa (Mao et al., 2007b). These data provide new constraints on elastic moduli and their pressure derivatives for hydrous olivine and wadsleyite. Using this data, we first examine the effect of H2O on bulk sound velocities under transition zone conditions because anelastic effects can be neglected in this case. At 410 km depth (~13.8 GPa, along a 1400°C adiabat), the bulk sound velocity of wadsleyite with 1 wt% H2O is 3.1% lower than for dry wadsleyite. Comparison of the seismic velocity jump across the 410-km discontinuity with the measured velocity contrast between wadsleyite and olivine provides a means to estimate the olivine abundance at 410-km depth. For mantle wadsleyite with 0.1-0.2 wt% H2O (Huang et al., 2005) and using experimentally determined olivine- wadsleyite H2O partition coefficients, the olivine abundance is found to be 40%, much lower than a pyrolite model. In order for a pyrolite composition to satisfy the seismic data, 1.2 wt. % H2O is needed in wadsleyite- a value greater than its maximum solubility under these conditions. The anomalously steep seismic gradient in the transition zone has been another feature of the region that has long defied explanation. We show that the seismic gradient can be matched if there is a gradient in H2O concentration across the transition zone such that the H2O content drops, for example, from 0.3 wt% at 410 km to 0.1 wt% at 520 km dpeth. For compressional and shear wave velocities, 0.1 wt% H2O in wadsleyite would lead to 0.3% and 0.4% reductions in VP and VS, respectively, neglecting any anelasticity. If the water content of wadsleyite was instead 1.0 wt. %, then the corresponding velocity reductions would be 3.3% and 3.6%. Following the work of Karato and Jung (1998), we have implemented a preliminary model accounting for the effect of H2O on anelasticity. This model indicates that 0.1 wt% H2O in wadsleyite could be responsible for reductions in shear velocities up to 1.0%.

  20. Incorporation of OH in olivine at high pressure: new experimental results

    NASA Astrophysics Data System (ADS)

    Mosenfelder, J. L.; Deligne, N. I.; Asimow, P. D.; Rossman, G. R.

    2002-12-01

    Numerous studies of natural and experimentally hydrated samples show that olivine can incorporate substantial amounts of hydrogen at high pressures, which has important implications for the rheology, melting behavior and transport properties of the mantle. We have conducted new experiments to further investigate the incorporation of hydroxide in olivine at high pressures (2-10 GPa) and temperatures (1100-1300°C) and varying oxygen fugacity and silica activity. In contrast to previous experiments, we calculate the concentration of OH in olivine by integrating the total absorbance from three FTIR spectra polarized in orthogonal directions and applying the new calibration of Bell et al. (in press). This procedure is inherently more accurate than the use of nominally unpolarized spectra and the generic calibration of Paterson (1982). We have used both fine-grained natural Fo90 olivine powders and oriented single crystals (500 x 600 x 700 ?m) as starting materials. Water in the experiments is provided by dehydration of talc and/or brucite, the ratio of which is chosen in order to establish equilibrium with either orthopyroxene or (Mg,Fe)O. In some experiments, Ni + NiO or Re + ReO is also added to the charge in order to influence the oxygen fugacity of the experiment. In experiments using fine-grained powders at 1150-1300°C, significant grain growth takes place, resulting in grain diameters up to ~300 ?m; suitably oriented grains for polarized spectroscopy are then identified using a variety of techniques. Our preliminary results include the following: 1) The spectra in all samples are dominated by sharp peaks in the range of ~3650-3400 cm-1, regardless of estimated silica activity. This is consistent with most previous experimental studies and, broadly speaking, with the spectra of most natural olivines. 2) The shapes of the spectra in all our samples are similar regardless of whether grain growth occurred under hydrous conditions or diffusion of H into existing large crystals took place. This strongly suggests that the mechanism of incorporation is identical in both cases. However, in experiments at 1100°C, large single crystals exhibit strongly zoned concentration profiles, consistent with the most recent diffusion data for OH in olivine (Kohlstedt and Mackwell, 1998). This complicates interpretation of these experiments and casts uncertainty on interpretation of previous experiments that used the same technique. 3) Comparison of experiments using Ni-NiO or Re-ReO as buffers shows little effect of oxygen fugacity (in this range, ~2 log units in fO2) on either concentration or incorporation mechanism. 4) Concentrations measured in the samples that used fine-grained starting materials are 2.5-3 times higher than the previous estimates for OH solubility measured by Kohlstedt et al. (1996). This difference is primarily attributed to use of the new calibration and measurement of polarized spectra. We are conducting further experiments to understand more quantitatively the roles of silica activity, oxygen fugacity, and starting point defect structure on incorporation of OH in olivine.

  1. Reaction Progress of Olivine Alteration as a Function of Time and CO2 Supply at 150°C - An Experimental Study

    NASA Astrophysics Data System (ADS)

    Prikryl, J.; Stefansson, A.

    2014-12-01

    Increased anthropogenic CO2 emissions have caused an imbalance in the Earth's carbon cycle causing climate changes. Interaction of CO2 with water and rock plays important role in geochemical cycle of carbon and among potential ways of reducing atmospheric CO2 by sequestration into carbonates. Olivine, among the main constituents of mafic and ultramafic rocks, is rich in Mg and Fe that can react with CO2 to form Mg-Fe carbonates like siderite and magnesite. Laboratory experiments were performed in batch-type titanium reactors to study the interaction between CO2-rich water and olivine under hydrothermal conditions. The experimental were conducted at 150°C, for 1 to 4 weeks, the CO2 concentration was 5 to 30 mmol/kg and the initial pH was around neutral. The olivine used was forsterite 93% from Åheim Olivine Pit-Norway. The alteration products and fluid chemistry were monitored as a function of time. Moreover, the results were supported with reaction path modeling to further constrain the olivine alteration and carbonate mineral formation mechanism. Initially forsterite dissolved releasing elements into solution. During this stage limited alteration products were formed and the solution pH was buffered by H+ uptake by olivine dissolution and CO2 concentration. Upon further reactions secondary phases started to form including chrysotile, brusite and mainly solid solution of iron-containing magnesite. This resulted in decrease of CO2 concentrations and eventually increased solution pH. Experiments with higher initial CO2 concentrations required longer period until CO2was consumed. Furthermore experiments with longer duration had quantitatively larger amount of precipitated minerals. Findings of this research represent platform for kinetic numerical simulations of olivine alteration and therefore provide insight into carbon storage in mafic rocks under in-situ conditions.

  2. Olivine compositions from the Hawaii Scientific Drilling Project, Phase 2: Evidence for a peridotite mantle source region

    SciTech Connect

    Putirka, K D; Ryerson, F J

    2008-10-27

    To the extent that mantle plumes reflect whole mantle convection, Hawaii may provide the clearest window into Earth's lower mantle. Samples from the Hawaii Scientific Drilling Project (HSDP) thus provide valuable tests for models of mantle mineralogy and composition. In this vein, it has been argued recently that Hawaiian olivines, especially those from the shield-building phase as sampled by HSDP, are so high in Ni (Sobolev et al., 2005, 2007), and that Hawaiian whole rocks are so low in CaO (Herzberg, 2006) and high in SiO{sub 2} (Hauri, 1996) that a peridotite mantle source cannot generate such compositions. The Hawaiian plume, so the argument goes, is thus supposedly rich in pyroxenite, and possibly olivine-free. However, comparisons of HSDP olivines to lherzolites, and HSDP whole rocks to lherzolites and partial melting experiments belie these premises. Testable predictions of the pyroxenite model also fail. New comparisons instead show that Hawaiian lavas can be produced from a peridotite source. First, it is unclear that the Hawaiian source is enriched in NiO. The NiO contents of olivines hosted by lherzolites (GEOROC) have the same range as olivines from the HSDP; indeed, the maximum NiO for olivines from lherzolites (0.6 wt.%) is as high as that reported for olivines from any oceanic volcano locality. There is a compositional separation between lherzolite- and HSDP-hosted olivines. But HSDP olivines are not NiO enriched so much as lherzolite olivines are higher in Fo at a given NiO. Lower Fo contents at Hawaii (at a given NiO) ensue because olivine compositions there follow a liquid line of descent, where both Ni and Mg decrease with differentiation. In contrast, subsolidus equilibria involving orthopyroxene enforce a higher and less variable Fo content for lherzolite-derived olivines. Moreover, the pyroxenite mantle model predicts that whole rocks with low CaO and high SiO{sub 2} should host olivines with high NiO. But in HSDP samples, neither correlation is evident. Whole rock compositions also support the peridotite mantle view. Primitive HSDP lavas (15% < MgO < 21%; F=0.2; D(Ni) = 4.2) indicate that the Hawaiian mantle has Ni = 1962 ppm, remarkably similar to estimates of pyrolite mantle (1960 ppm; McDonough and Sun, 1990) and somewhat less than the average lherzolite (2165 ppm). Ni contents at Hawaii are higher than MORB, but that is because the MORB source is Ni-depleted (relative to lherzolites), rather than the Hawaiian source being enriched. Finally, experimentally produced, peridotite-equilibrated liquids bracket the compositions of primitive HSDP lavas for all oxides but TiO{sub 2}. One experiment in particular (Takahashi et al., 1993; 46 kbar, 1720 C) comes remarkably close to reproducing primitive HSDP compositions. TiO{sub 2}, the sole exception, must be 0.68 wt.% in the Hawaiian source (F = 0.2; D(TiO{sub 2}) = 0.21), which falls at the 99.8% quantile for lherzolite TiO{sub 2} contents. Enrichments are not isolated to Ti, but extend to other high field strength elements (Hf, Zr and Y), and moderately incompatible elements (Eu, Na); none, however, require mantle source concentrations in excess of observed lherzolite values. These same enrichments are evident, though more subdued, in the MORB mantle source, and so are apparently characteristic of the convective mantle.

  3. Highly impregnated slow-spread lithosphere : microstructure and geochemistry of olivine-rich troctolites from IODP Hole U1309D

    NASA Astrophysics Data System (ADS)

    Ildefonse, B.; Drouin, M.; Godard, M.

    2009-04-01

    IODP Expeditions 304-305 sampled the Atlantis Massif, an oceanic core complex located at 30°N in the inside corner of the intersection of the Mid-Atlantic Ridge with the Atlantis Fracture Zone. IODP Hole U1309D was drilled to 1415.5 meters below seafloor; it is the second deepest hole in slow-spreading crust, after Ocean Drilling Program (ODP) Hole 735B on the Southwest Indian Ridge. The recovered rocks are mostly gabbroic. We present a petrostructural (EBSD) and in-situ geochemical (EPMA, LA-ICPMS and LA-HR-ICPMS) study of olivine-rich troctolites (ol > 70%; 5.5 % of recovered section) and associated gabbros. Olivine-rich troctolites from Hole U1309D display poikilitic textures, with olivine ranging from coarse-grained subhedral crystals to medium-grained rounded crystals, embedded in large, undeformed clinopyroxene and plagioclase poikiloblasts. Trace element compositions of clinopyroxene and plagioclase poikiloblasts indicate that they crystallized from the same depleted MORB melt in both olivine-rich troctolites and associated gabbros. Olivine trace element compositions appear too depleted in light REE to be in equilibrium with plagioclase and clinopyroxene. Olivine crystallographic preferred orientations are weak, and misorientations are consistent with deformation by dislocation creep with activation of the high-temperature (010) [100] slip system, commonly described in asthenospheric mantle. The fabrics also display a relatively strong uncommon [001] concentration that we interpret as resulting from abundant melt impregnation. The joint study of geochemical processes and microstructures in these rocks suggest a complex crystallization history in an open system with percolation of large volume of MORB-type melt that postdate olivine crystal-plastic deformation. Although the mantle origin of the olivine is difficult to demonstrate unequivocally, we propose that olivine-rich troctolites represent the ultimate residue of melt-mantle reaction processes. Our results are consistent with the formation of oceanic core complexes associated with relatively strong magmatic activity, and with the crystallization of most of melt in the Atlantis Massif lithosphere without basaltic counterpart erupted on the seafloor.

  4. P-rich olivines in a melt vein of a composite mantle xenolith: implications for crystal growth and kinetics

    NASA Astrophysics Data System (ADS)

    Baziotis, Ioannis; Asimow, Paul D.; Ntaflos, Theodoros; Koroneos, Antonios; Perugini, Diego; Stolper, Edward M.

    2014-05-01

    The mineral chemistry of mantle xenoliths, and in particular the presence of phosphorus (P) - a moderately incompatible and slowly diffusing element - may preserve the history of mineral growth and constrain timescales of pre-eruption petrogenetic processes (Boesenberg & Hewins 2010). P-rich zones in olivine may reflect incorporation of P in excess of equilibrium partitioning during rapid growth, in which case zoning patterns primarily record crystal growth rate variations (Milman-Barris et al. 2008; Stolper et al. 2009). We investigated using EMP analyses and X-ray maps a composite amphibole-bearing, mantle xenolith (sample: Ci-1-196) from Cima Volcanic Field (California, USA) that contains second generation P-rich olivines. The xenolith contains multiple lherzolite, websterite, and dunite layers. The host magma (not preserved in our hand-specimen) is thought to be a hawaiite (Wilshire et al. 1988). A thin (average ~200 ?m width), dark layer is present along the contact between lherzolite and websterite. Interpreted as a rapidly crystallized melt, this layer consists of olivine + glass + plagioclase + spinel + clinopyroxene + apatite + ilmenite. The layer contains olivines (Fo83-89.3) with 0.03-0.52 wt.% P2O5; the P-rich olivines (P2O5 >0.1 wt.%) are Fo85 to Fo89.3. Apatite inclusions are present near the rim of P-rich olivine (Fo85) and in plagioclase (An54). Glass is widespread (~15 vol.%) in the layer, having variable composition with P2O5 up to 1.2 wt.%. Plagioclase occurs as prismatic, flow-oriented crystals, parallel to the elongation of the layer or intergranular crystals between olivine and/or clinopyroxene. Clinopyroxene formed either as crystallized products within the melt layer or by reaction at the interface between melt and matrix olivine. Spinel occurs as inclusions in the olivine or associated with plagioclase and glass, showing anhedral shape and linear edges; spinel composition varies from chromite to Ti-chromite from core to rim, with an outer rim rich in ulvöspinel. Ilmenite occurs as idiomorphic crystals within the layer or as thin rims (

  5. CO2 Geological Storage in Olivine Rich Basaltic Aquifers: New Insights From Flow-Through Experiments

    NASA Astrophysics Data System (ADS)

    Peuble, S.; Godard, M.; Luquot, L.; Gibert, B.; Mainprice, D.; Martinez, I.; Gouze, P.

    2012-04-01

    Injection of CO2-rich fluids into (ultra-)mafic aquifers is one of the methods envisaged for mitigation of increasing atmospheric CO2 concentrations. These rocks, rich in Mg, Fe and Ca, have a high potential to trap CO2 as carbonates minerals. However, the role of reaction-transport processes has not been investigated to predict the capacity and sustainability for CO2 storage in these highly reactive systems. We performed three percolation-reaction experiments on the ICARE-2 bench (Luquot et al., 2012) at 180°C and total pressure of 12 MPa. NaHCO3 rich water (0.5 mol/L) mixed with CO2 (Pco2 = 10 MPa) were injected at an initial injection rate of 1 mL/h for exp. 1 and 2, and 0.1 mL/h for exp. 3 into sintered olivine analogues of accumulation zones in basaltic flows. The sintered samples comprise mainly olivine Fo87 (Mg1.75Fe0.24Ni0.01SiO4) with minor basalt and spinel (Mg0.57Cr1.19Ti0.03Mn0.01Fe0.66Al0.54O4). The initial porosity and permeability of samples ranges from 4 to 7 % and 30x10-18 to 400x10-18 m2 respectively. All experiments resulted in a strong permeability decrease (down to 10-18 m2) after 90 hours for exp. 1 and 2 and 55 hours for exp 3. The enrichment in several major and trace elements observed in outlet fluids indicates that dissolution of olivine (Si, Co), basalt (Al, Zr) and spinel (Cr, V) occurred, while the depleted Ca and Mg composition of outlet fluids indicates precipitation of Ca-Mg rich phases. Analyses of reacted samples indicate that all basalt grains were dissolved and the spatial distribution of etch pits on forsterite surfaces suggest the anisotropic dissolution of olivine. Ankerite and calcite is observed in pores of samples after exp. 1 and 2, and well-developed magnesite (Mg0.88Fe0.11Ca0.01CO3) and dolomite replacing dissolved olivine is found in exp.3 sample. The (001) planes of magnesite and dolomite are parallel to the (100) plane of forsterite. Downstream, no carbonates were found but the growth of relatively large (up to 5 µm) Mg-Fe rich phyllosilicates plates perpendicular to (at the expense of ?) olivine surfaces was observed. The precipitation of these serpentine type minerals may explain the strong decrease in permeability during experiments. Carbonation was relatively efficient in our experiments: between 0.003g (exp.3) and 0.015 g (exp.1 & 2) of CO2 per gram of sample was trapped as carbonates. When these analyses are upscaled to the size of an injection site, they correspond to an average yield of 3.6 to 10.6 Mtons of CO2/km3/day. Our results indicate a strong control of flow rates on carbonation, and also on hydration reactions. This implies not only variations of the CO2 storage capacity of the basaltic aquifer with distance to the injection well, but also that controlling the injection rate would allow enhancing the efficiency of in situ carbonation. Luquot L., Andreani M., Gouze P., Camps P. (2012) CO2 percolation experiment through chlorite/zeolite-rich sandstone (Pretty-Hill Formation - Otway-Basin-Australia), Chemical Geology 294-295, 75-88, doi:10.1016/j.chemgeo.2011.11.018.

  6. Natural dissociation of olivine to (Mg,Fe)SiO3 perovskite and magnesiowüstite in a shocked Martian meteorite

    PubMed Central

    Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Shin; Kimura, Makoto; El Goresy, Ahmed; Sakai, Takeshi; Nagase, Toshiro; Hiraga, Kenji; Hirao, Naohisa; Ohishi, Yasuo

    2011-01-01

    We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine (Fa34-41) adjacent to or entrained in the shock melt vein and melt pockets of Martian meteorite olivine-phyric shergottite Dar al Gani 735 dissociated into (Mg,Fe)SiO3 perovskite (Pv)+magnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular (Mg,Fe)SiO3 Pv and Mw have 50–100 nm in diameter, and lamellar (Mg,Fe)SiO3 Pv and Mw have approximately 20 and approximately 10 nm in thickness, respectively. Partitioning coefficient, KPv/Mw = [FeO/MgO]/[FeO/MgO]Mw, between (Mg,Fe)SiO3 Pv and Mw in equigranular and lamellar textures are approximately 0.15 and approximately 0.78, respectively. The dissociation of olivine implies that the pressure and temperature conditions recorded in the shock melt vein and melt pockets during the dynamic event were approximately 25 GPa but 700?°C at least. PMID:21444781

  7. Microstructural evidence for complex formation histories of amoeboid olivine aggregates from the ALHA77307 CO3.0 chondrite

    NASA Astrophysics Data System (ADS)

    Han, Jangmi; Brearley, Adrian J.

    2015-05-01

    The microstructures and compositions of olivine and refractory components in six amoeboid olivine aggregates (AOAs) in the Allan Hills A77307 CO3.0 chondrite have been characterized in detail using the focused ion beam sample preparation technique with transmission electron microscopy. In the AOAs, refractory components (perovskite, melilite, spinel, anorthite, and Al-Ti-bearing diopside) provide evidence of a high degree of textural and compositional heterogeneity, suggesting that these phases have formed by disequilibrium gas-solid condensation at high temperatures under highly dynamic conditions. We infer different possible reactions of early-condensed solid minerals (perovskite and spinel) with a nebular gas, forming diopside with wide ranges of Al and Ti contents and/or anorthite. The progressive, incomplete consumption of spinel in these reactions may have resulted in the Cr enrichment in the remaining, unreacted spinel in the AOAs. In contrast to the refractory components, olivines in the AOAs have equilibrated textures with 120° triple junctions, indicating that the AOAs were subjected to high-temperature annealing after agglomeration of olivine and refractory components. Because the AOAs consist of fine-grained olivine grains with numerous pores, the annealing is constrained by experimental data to have occurred for a short duration of the order of a few hours to tens of hours depending on the annealing temperature. In comparison, the effects of annealing on the refractory components are minimal, probably due to pinning of grain boundaries in the multiphase assemblages that inhibited grain growth.

  8. Natural dissociation of olivine to (Mg,Fe)SiO3 perovskite and magnesiowustite in a shocked Martian meteorite.

    PubMed

    Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Shin; Kimura, Makoto; El Goresy, Ahmed; Sakai, Takeshi; Nagase, Toshiro; Hiraga, Kenji; Hirao, Naohisa; Ohishi, Yasuo

    2011-04-12

    We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine (Fa(34-41)) adjacent to or entrained in the shock melt vein and melt pockets of Martian meteorite olivine-phyric shergottite Dar al Gani 735 dissociated into (Mg,Fe)SiO(3) perovskite (Pv)+magnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular (Mg,Fe)SiO(3) Pv and Mw have 50-100 nm in diameter, and lamellar (Mg,Fe)SiO(3) Pv and Mw have approximately 20 and approximately 10 nm in thickness, respectively. Partitioning coefficient, K(Pv/Mw) = [FeO/MgO]/[FeO/MgO](Mw), between (Mg,Fe)SiO(3) Pv and Mw in equigranular and lamellar textures are approximately 0.15 and approximately 0.78, respectively. The dissociation of olivine implies that the pressure and temperature conditions recorded in the shock melt vein and melt pockets during the dynamic event were approximately 25 GPa but 700?°C at least. PMID:21444781

  9. Natural fumarolic alteration of fluorapatite, olivine, and basaltic glass, and implications for habitable environments on Mars.

    PubMed

    Hausrath, Elisabeth M; Tschauner, Oliver

    2013-11-01

    Fumaroles represent a very important potential habitat on Mars because they contain water and nutrients. Global deposition of volcanic sulfate aerosols may also have been an important soil-forming process affecting large areas of Mars. Here we identify alteration from the Senator fumarole, northwest Nevada, USA, and in low-temperature environments near the fumarole to help interpret fumarolic and acid vapor alteration of rocks and soils on Mars. We analyzed soil samples and fluorapatite, olivine, and basaltic glass placed at and near the fumarole in in situ mineral alteration experiments designed to measure weathering under natural field conditions. Using synchrotron X-ray diffraction, we clearly observe hydroxyl-carbonate-bearing fluorapatite as a fumarolic alteration product of the original material, fluorapatite. The composition of apatites as well as secondary phosphates has been previously used to infer magmatic conditions as well as fumarolic conditions on Mars. To our knowledge, the observations reported here represent the first documented instance of formation of hydroxyl-carbonate-bearing apatite from fluorapatite in a field experiment. Retreat of olivine surfaces, as well as abundant NH4-containing minerals, was also characteristic of fumarolic alteration. In contrast, alteration in the nearby low-temperature environment resulted in formation of large pits on olivine surfaces, which were clearly distinguishable from the fumarolic alteration. Raman signatures of some fumarolically impacted surfaces are consistent with detection of the biological molecules chlorophyll and scytenomin, potentially useful biosignatures. Observations of altered minerals on Mars may therefore help identify the environment of formation and understand the aqueous history and potential habitability of that planet. PMID:24283927

  10. Survival times of anomalous melt inclusions from element diffusion in olivine and chromite.

    PubMed

    Spandler, C; O'Neill, H St C; Kamenetsky, V S

    2007-05-17

    The chemical composition of basaltic magma erupted at the Earth's surface is the end product of a complex series of processes, beginning with partial melting and melt extraction from a mantle source and ending with fractional crystallization and crustal assimilation at lower pressures. It has been proposed that studying inclusions of melt trapped in early crystallizing phenocrysts such as Mg-rich olivine and chromite may help petrologists to see beyond the later-stage processes and back to the origin of the partial melts in the mantle. Melt inclusion suites often span a much greater compositional range than associated erupted lavas, and a significant minority of inclusions carry distinct compositions that have been claimed to sample melts from earlier stages of melt production, preserving separate contributions from mantle heterogeneities. This hypothesis is underpinned by the assumption that melt inclusions, once trapped, remain chemically isolated from the external magma for all elements except those that are compatible in the host minerals. Here we show that the fluxes of rare-earth elements through olivine and chromite by lattice diffusion are sufficiently rapid at magmatic temperatures to re-equilibrate completely the rare-earth-element patterns of trapped melt inclusions in times that are short compared to those estimated for the production and ascent of mantle-derived magma or for magma residence in the crust. Phenocryst-hosted melt inclusions with anomalous trace-element signatures must therefore form shortly before magma eruption and cooling. We conclude that the assumption of chemical isolation of incompatible elements in olivine- and chromite-hosted melt inclusions is not valid, and we call for re-evaluation of the popular interpretation that anomalous melt inclusions represent preserved samples of unmodified mantle melts. PMID:17507980

  11. A record of lower crustal chamber sizes from Icelandic olivine-hosted melt inclusions

    NASA Astrophysics Data System (ADS)

    Maclennan, J.

    2014-12-01

    Melt inclusions hosted in olivines from single Icelandic eruptions of basalt have highly variable compositions, particularly in terms of their incompatible element concentrations, concentration ratios and Pb-isotopes. This compositional diversity reflects variation in the composition of mantle melts supplied to individual volcanic plumbing systems. The variance of inclusion compositions decreases as the forsterite content of the host olivine decreases: a relationship that is readily understood in terms of concurrent mixing and crystallisation of primitive melts. The availability of a large number of melt inclusion analyses from Icelandic olivines (>500) allows for robust quantification of the relative rates of melt cooling and passive tracer mixing in the lower crustal chambers where inclusion entrapment occurred. This coupling of cooling and mixing is likely to reflect convection in the melt layer of the chambers. The fact that the Icelandic observations preserve a record of both mixing and cooling indicates that the characteristic timescales of these processes are similar. A simple 1D model of convection in a basaltic sill was developed, with the cooling either controlled by temperature dependence of viscosity of the melt or by the rate of conduction of heat through the rocks of the chamber roof. The timescales of cooling of melt and mixing of passive tracers are proportional to different powers of the Rayleigh number of the sill. Therefore, models that match the Icelandic observations involve sills with a surprisingly small range of thicknesses: the model timescales of mixing and cooling are similar only if the thickness of the sill is <10 m. These sill thicknesses are similar to those proposed for the lower oceanic crust based on observations from ophiolites, and may indicate that small sills play a dominant role in the evolution of basaltic melts.

  12. Oxygen diffusion in olivine: Effect of oxygen fugacity and implications for creep

    SciTech Connect

    Ryerson, F. J.; Durham, W. B.; Cherniak, D. J.; Lanford, W. A.

    1989-04-10

    Oxygen self-diffusion experiments on single crystals of San Carlosolivine (/similar to/Fo/sub 92/) at 1200/degree/less than or equal to/ital T/less than or equal to1400 /degree/C, oxygen fugacities(/ital f//sub O2/) along the Ni-NiO and Fe-FeO buffers, and silica activityat the olivine-orthopyroxene buffer yielded results that follow therelationship /ital D/=2.6/times/10/sup /minus/10//ital f/ /sub O2//sup 0.21+-0.03/ exp (/minus/266+-11)(kJ mol/sup /minus/1///ital RT/), where/ital D/ is the diffusion coefficient in m/sup 2/ s/sup /minus/1/ and /ital f//sub O2/ is givenin pascals. The activation energy compares reasonably well with results forpure forsterite. The positive dependence of /ital f//sub O/sub 2// implies that theoxygen defect responsible for diffusion is an interstitial rather than a morestericaly reasonable oxygen vacancy. Diffusion of oxygen in other close-packedoxides has also shown a positive dependence on /ital f//sub O2/. The rate ofcreep of single-crystal olivine at fixed orthopyroxene activity also showsa positive /ital f//sub O2/ dependence. If oxygen interstitials should be shown tobe unimportant in oxygen diffusion in oxides, then coupled mechanisms such ascountervacancy diffusion must be appealed to in order to explain the positive/ital f//sub O2/ dependence. Such processes are rate-limited by the diffusion ofmetal vacancies which also display a positive /ital f//sub O2/ dependence inolivine. Compared with data for silicon diffusion in forsterite, our dataindicate that oxygen is not the slowest diffusing species in olivine.

  13. Octahedral cation ordering in Mg, Fe2+-olivine: an optical absorption spectroscopic study

    NASA Astrophysics Data System (ADS)

    Taran, Michail N.; Koch-Müller, Monika

    2006-11-01

    Polarized optical absorption spectra of natural olivine, Fa10Fo90, were measured before and after annealing/quenching experiments performed at 650, 800, 1,000 and 1,200°C under controlled oxygen fugacity. It was found that the annealing induces weak but definite changes in the olivine spectra. The intensity of the spin-allowed Z > X-polarized band at 9,560 cm-1 and shoulder at ˜8,300 cm-1 attributed to Fe2+(M2), continuously decreases with annealing temperature, whereas a weaker band at ˜11,600 cm-1 assigned to electronic spin-allowed transitions of Fe2+(M1), increases. This evidently shows that annealing treatments cause a redistribution of Fe2+ from M2 to M1. The fractionation increases with increasing temperature. This observation is in good correspondence with many diffraction structural studies of natural and synthetic olivines, as well as with recent Raman and Mössbauer investigations by Kolesov and Geiger (Mitt Österr Mineral Ges 149:48, 2004) and Morozov et al. (Eur J Mineral 17:495 500, 2005) evidencing a weak tendency of Fe to order into the M1 site with increasing temperature. However, this deduction is incompatible with the results of the in situ neutron power diffraction study of synthetic FeMgSiO4 by Redfern et al. (Phys Chem Minerals 27:630 637, 2000). Polarization properties of the UV absorption edge, attributed to ligand-to-metal charge-transfer transitions in Fe3+, changes from Y > X ? Z in natural samples to a weak Y ? X ? Z-pleochroism in annealed ones. This may be due to redistribution of a small content of Fe3+ among M1 and M2 structural sites.

  14. Comparison and calibration of nonheating paleointensity methods: A case study using dusty olivine

    NASA Astrophysics Data System (ADS)

    Lappe, Sophie-Charlotte L. L.; Harrison, Richard J.; Feinberg, Joshua M.; Muxworthy, Adrian

    2013-07-01

    We present a comparative study of nonheating paleointensity methods, with the aim of determining the optimum method for obtaining paleointensities from "dusty olivine" in chondritic meteorites. The REM method, whereby thermoremanent magnetization (TRM) is normalized by saturation isothermal remanent magnetization (SIRM), is shown to "over normalize" TRM in dusty olivine due to the transformation of stable single-vortex (SV) states to metastable single-domain (SD) states in a saturating field. The problem of over normalization is reduced in the REMc and REM' methods, which more effectively isolate the high-coercivity stable SD component of remanence. A calibration factor of f = 1600 (1000 < f < 2900) is derived for the REM' method. Anhysteric remanent magnetization (ARM) is shown to be a near perfect analogue of TRM in the stable SD component of dusty olivine. ARM normalization of the high-coercivity (100-150 mT) remanence with a calibration factor fARM = 0.91 (0.7 < fARM < 1.2) yields paleofield estimates within ± 30% of the actual field values for SD dominated samples. A Preisach method for simulating TRM acquisition using information extracted from first-order reversal curve (FORC) diagrams is shown to work well for SD dominated samples, but fails when there is a large proportion of SV remanence carriers. The failure occurs because (1) SV states are not properly incorporated into the Preisach distribution of remanence carriers, and (2) the acquisition of TRM by SV states is not properly modeled by the underlying SD thermal relaxation theory.

  15. Alignment of olivine crystals during diffusion creep in oceanic peridotite mylonites

    NASA Astrophysics Data System (ADS)

    Deems, N. J.; Warren, J. M.; Wolfson-Schwehr, M.

    2014-12-01

    At small grain sizes (<10 µm), olivine is expected to deform by diffusion creep at lithospheric conditions. Microstructural analysis by electron backscatter diffraction of 13 peridotite mylonites from St. Paul's Rocks (SPR) indicates that olivine has a pronounced axial-[010] lattice preferred orientation (i.e. [010] clusters perpendicular to foliation, while [100] and [001] are dispersed in the foliation plane) and a mean grain size of ~7µm. Holtzman et al. (2003) has observed similar LPOs in partially molten samples experimentally deformed under simple shear at lithospheric conditions. The occurrence of a lattice preferred orientation (LPO) is typically interpreted as indicating deformation by dislocation creep. In addition, compositional maps of the samples show that amphibole (pargasite) is ubiquitous. As the presence of pargasite in peridotites is controlled in part by the activity of plagioclase and water at high temperatures (Lynkins and Jenkins, 1992), we infer this as evidence for the presence of pre- to syn-tectonic trapped melt. In order to explain the observed LPO in SPR mylonites, we evaluate the hypothesis that alignment occurred during diffusion creep, such as observed in experiments by Sundberg and Cooper (2008) and Miyazaki et al., (2013). To explore this hypothesis, we conducted analyses of low angle (2-10°) rotation axis inverse pole figures (IPFs), which can often provide insight into the operative slip system(s). Analyses of low angle IPFs from SPR, however, showed no definitive correlation to any one particular slip system. On the other hand, high angle IPFs showed intense clustering of rotational axes at 75-90° about [010], indicating that [100] and [001] align nearly perpendicular to [010]. Based on the IPF analysis and evidence of pre- to syn-tectonic melt, we conclude that the presence of melt lubricated grain boundaries, which resulted in rigid rotation of grains and alignment of the [010] axes controlled by the orthorhombic crystal habit of olivine. That is, as [010] is shortest in terms of habit, this allows [010] to align perpendicular to the shear plane, while the [100] and [001] axes are dispersed in the plane parallel to shear. Thus, SPR mylonites represent a natural example of olivine LPO formation during diffusion creep.

  16. Comparative pathological aspects of chronic olivine and silica inhalation in mice.

    PubMed

    Wilson, T; Scheuchenzuber, W J; Eskew, M L; Zarkower, A

    1986-04-01

    A comparative study was done in mice on the effects of silica and olivine inhalation. The exposure periods in the dust chambers were for periods of 150, 300, and 570 days, with the longest time period covering a large portion of the predicted life span of the Balb/c mouse. Detailed necropsies including histology were done at the end of the exposures and at 30 and 150 days following removal of animals from the 150- and 300-day dust exposures. The results indicate that silica causes considerably more tissue damage in lungs and mediastinal lymph nodes, leading to granulomas. PMID:3007105

  17. Petrology and Mineral Chemistry of New Olivine-Phyric Shergottite RBT04262

    NASA Technical Reports Server (NTRS)

    Dalton, H. A.; Peslier, A. H.; Brandon, A. D.; Lee, C.-T. A.; Lapen, T. J.

    2008-01-01

    RBT04262 was found by the 2004-2005 ANSMET team at the Roberts Massif in Antarctica. It is paired with RBT04261 and is classified as an olivine-phyric shergottite. RBT04261 is 4.0 x 3.5 x 2.5 cm and 78.8 g, and RBT04262 is 6.5 x 5.5 x 3.5 cm and 204.6 g. Both were partially covered by a fusion crust [1]. Chemical analysis and mapping of this meteorite was performed using the Cameca SX100 electron microprobe at NASA Johnson Space Center.

  18. Sulfidation of Mg-rich olivine and the stability of niningerite in enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Fleet, M. E.; Macrae, N. D.

    1987-06-01

    When Mg-rich olivine is heated with excess (Fe,Ni) monosulfide and graphite in a sealed silica vessel at 1200 C, it is sulfidized to niningerite and clinoenstatite. The quenched experimental assemblage of clinoenstatite + troilite + niningerite + alloy + silicide + graphite is equivalent to the reduced mineral assemblage of EH enstatite chondrites. The present phase relations suggest that niningerite in EH chondrites could have been produced by sulfidation of Mg-rich silicates during either accretion or metamorphism at low CO fugacities; niningerite, however, is unstable under the anticipated conditions of recrystallization of EL enstatite chondrites.

  19. Estimates of olivine-basaltic melt electrical conductivity using a digital rock physics approach

    NASA Astrophysics Data System (ADS)

    Miller, Kevin J.; Montési, Laurent G. J.; Zhu, Wen-lu

    2015-12-01

    Estimates of melt content beneath fast-spreading mid-ocean ridges inferred from magnetotelluric tomography (MT) vary between 0.01 and 0.10. Much of this variation may stem from a lack of understanding of how the grain-scale melt geometry influences the bulk electrical conductivity of a partially molten rock, especially at low melt fraction. We compute bulk electrical conductivity of olivine-basalt aggregates over 0.02 to 0.20 melt fraction by simulating electric current in experimentally obtained partially molten geometries. Olivine-basalt aggregates were synthesized by hot-pressing San Carlos olivine and high-alumina basalt in a solid-medium piston-cylinder apparatus. Run conditions for experimental charges were 1.5 GPa and 1350 °C. Upon completion, charges were quenched and cored. Samples were imaged using synchrotron X-ray micro-computed tomography (?-CT). The resulting high-resolution, 3-dimensional (3-D) image of the melt distribution constitutes a digital rock sample, on which numerical simulations were conducted to estimate material properties. To compute bulk electrical conductivity, we simulated a direct current measurement by solving the current continuity equation, assuming electrical conductivities for olivine and melt. An application of Ohm's Law yields the bulk electrical conductivity of the partially molten region. The bulk electrical conductivity values for nominally dry materials follow a power-law relationship ?bulk = C?melt?m with fit parameters m = 1.3 ± 0.3 and C = 0.66 ± 0.06. Laminar fluid flow simulations were conducted on the same partially molten geometries to obtain permeability, and the respective pathways for electrical current and fluid flow over the same melt geometry were compared. Our results indicate that the pathways for flow fluid are different from those for electric current. Electrical tortuosity is lower than fluid flow tortuosity. The simulation results are compared to existing experimental data, and the potential influence of volatiles and melt films on electrical conductivity of partially molten rocks is discussed.

  20. The influence of magma degassing on entrapment pressures recorded in olivine-hosted melt inclusions

    NASA Astrophysics Data System (ADS)

    Gaetani, G. A.

    2013-12-01

    The concentrations of H2O and CO2 in olivine-hosted melt inclusions provide estimates for the pressures at which they were entrapped, and represent an important source of information on the depths at which basaltic magmas crystallize [1]. Results from recent dehydration experiments demonstrate that diffusive loss of H2O from melt inclusions, driven by degassing of the external magma, leads to significant decreases to pressure within the inclusion [2, 3]. This, in turn, lowers the solubility of CO2 in the included melt causing a vapor to exsolve and form a bubble. This process has the potential to significantly modify estimates of entrapment pressures derived from volatile concentrations in olivine hosted melt inclusions. I have developed a quantitative model that describes this process, allowing the influence of degassing on entrapment pressures to be rigorously evaluated. Diffusive loss of H2O from the inclusions was determined using the model of [3]. An equation of state (EOS) for the silicate melt was taken from the results of [4] and [5], while the EOS for H2O-CO2 vapor was taken from [6]. The solubilities of H2O and CO2 in the silicate melt were derived from VolatileCalc [7]. Modeling results demonstrate that degassing of H2O-rich magma produces significant pressure drops, so that entrapment pressures never exceed crustal values and always represent a minimum. Conversely, degassing of H2O-poor magma does not significantly perturb the H2O content of olivine-hosted melt inclusions. Therefore, these inclusions preserve reliable records of the pressures at which they were entrapped. These results are consistent with a global compilation of olivine-hosted melt inclusion entrapment pressures presented by [3]. References: [1] Wanless, VD, and Shaw, AM, Nature Geosci, 5, 651-655 (2012); [2] Gaetani, GA, et al., Geology, 40, 915-918 (2012); [3] Bucholz, CE, et al., Earth Planet Sci Lett, 374, 145-155 (2013); [4] Lange, R. A., and Carmichael, ISE, Geochim Cosmochim Acta, 51, 2931-2946, (1987); [5] Kress, VC, and Carmichael, ISE, Contrib Mineral Petrol, 108, 82-92 (1991); [6] Duan, Z, and Zhang, Z, Geochim Cosmochim Acta, 70, 2311-2324 (2006); [7] Newman, S, and Lowenstern, JB, Comput Geosci, 28, 597-604 (2002).

  1. Catalytic reforming of toluene as tar model compound: effect of Ce and Ce-Mg promoter using Ni/olivine catalyst.

    PubMed

    Zhang, Ruiqin; Wang, Huajian; Hou, Xiaoxue

    2014-02-01

    Tar produced by biomass gasification as a route of renewable energy must be removed before the gas can be used. This study was undertaken using toluene as a model tar compound for evaluating its steam reforming conversion with three Ni-based catalysts, Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. Effects of Ce and Mg promoters on the reaction activity and coke deposition were studied. Overall the performance of Ce and Mg promoted Ni/olivine catalysts is better than that of only Ce promoter and Ni/olivine alone. The experimental results indicate that Ni-Ce-Mg/olivine catalysts could improve the resistance to carbon deposition, enhance energy gases yield and resist 10ppm H2S poison at 100mLmin(-1) for up to 400min. Furthermore, the activity of catalysts was related to the steam/carbon (S/C) ratios; at S/C ratio=5, T=790°C, space velocity=782h(-1) and t=2h, the Ni-Ce-Mg/olivine system yielded 89% toluene conversion, 5.6Lh(-1) product gas rate, 62.6mol% H2 content and 10% (mol useful gas mol(-1) toluene) energy yield. Moreover, at low S/C ratio, it had higher reaction activity and better ability to prevent coking. There is a small amount of carbon deposition in the form of amorphous carbon after 7h. Various characterization techniques such as XRD, FTIR and thermogravimetric were performed to investigate the coke deposition of Ni/olivine, Ni-Ce/olivine and Ni-Ce-Mg/olivine. It is suggested that 3% Ni-1% Ce-1% Mg/olivine was the most promising catalyst due to its minimum coke amount and the lower activation energy of coke burning. PMID:24275153

  2. Variations of olivine abundance and grain size in the Snap Lake kimberlite intrusion, Northwest Territories, Canada: A possible proxy for diamonds

    NASA Astrophysics Data System (ADS)

    Field, M.; Gernon, T. M.; Mock, A.; Walters, A.; Sparks, R. S. J.; Jerram, D. A.

    2009-11-01

    The Snap Lake hypabyssal kimberlite is a 15° inclined intrusion that intrudes Archaean rocks of the Slave craton. Mapping has identified two main lithofacies within the intrusion, olivine-rich kimberlite (ORK) and olivine-poor kimberlite (OPK). Extensive bulk sampling has demonstrated that diamonds vary in both abundance and size across the intrusion. Since fresh forsteritic olivine and diamond possess similar densities they can be expected to be hydraulically equivalent. This study investigates the local scale variation of olivine grain size and content using image analysis, and whether olivine can be used as a proxy for diamond concentration and size. Direct measurement of diamonds is made difficult by extremely low concentrations of around 0.4 ppm and by the inability of the sampling methodology to sample selectively. Olivines from the two kimberlite varieties possess distinctly different crystal size distributions and this, together with contrasting groundmass textures, mineralogy and phlogopite compositions, indicates that the OPK and ORK represent two distinct batches of kimberlite magma. The general lack of sorting of olivine grains and the presence of decussate phlogopite textures in the ORK indicate that this magma crystallized rapidly, but was probably preceded by the OPK which had a more complex crystallization history as revealed by complex zoning patterns of its phlogopite grains. A methodology for comparing olivine and diamond size distributions has been developed, and a strong correlation between diamond and olivine size distributions is demonstrated. The correlation is used to demonstrate that diamond size distributions can be predicted from the proportions of OPK and ORK that comprise each bulk sample. It can be concluded that the two textural varieties of kimberlite possess distinctly different olivine (and diamond?) populations and that olivines are a good proxy for understanding diamond distributions at a local scale in the Snap Lake intrusion.

  3. Three-Dimensional Coherent X-Ray Diffraction Imaging of Molten Iron in Mantle Olivine at Nanoscale Resolution

    NASA Astrophysics Data System (ADS)

    Jiang, Huaidong; Xu, Rui; Chen, Chien-Chun; Yang, Wenge; Fan, Jiadong; Tao, Xutang; Song, Changyong; Kohmura, Yoshiki; Xiao, Tiqiao; Wang, Yong; Fei, Yingwei; Ishikawa, Tetsuya; Mao, Wendy L.; Miao, Jianwei

    2013-05-01

    We report quantitative 3D coherent x-ray diffraction imaging of a molten Fe-rich alloy and crystalline olivine sample, synthesized at 6 GPa and 1800°C, with nanoscale resolution. The 3D mass density map is determined and the 3D distribution of the Fe-rich and Fe-S phases in the olivine-Fe-S sample is observed. Our results indicate that the Fe-rich melt exhibits varied 3D shapes and sizes in the olivine matrix. This work has potential for not only improving our understanding of the complex interactions between Fe-rich core-forming melts and mantle silicate phases but also paves the way for quantitative 3D imaging of materials at nanoscale resolution under extreme pressures and temperatures.

  4. RESEARCH PAPER Facile synthesis of porous-carbon/LiFePO4 nanocomposites

    E-print Network

    Park, Byungwoo

    RESEARCH PAPER Facile synthesis of porous-carbon/LiFePO4 nanocomposites Sungun Wi · Seunghoon Nam online: 27 November 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Porous-carbon/LiFePO4? diffusivity. Keywords Li-ion batteries Á LiFePO4 Á Nanocomposites Á Porous carbon Introduction Olivine lithium

  5. Doped LiFePO? cathodes for high power density lithium ion batteries

    E-print Network

    Bloking, Jason T. (Jason Thompson), 1979-

    2003-01-01

    Olivine LiFePO4 has received much attention recently as a promising storage compound for cathodes in lithium ion batteries. It has an energy density similar to that of LiCoO 2, the current industry standard for cathode ...

  6. Influence of Water on Olivine-Wadsleyite Phase Transformation and Water Partitioning near 410-km Seismic Discontinuity

    SciTech Connect

    Litasov, Konstantin D.; Ohtani, Eiji; Ghosh, Sujoy; Kagi, Hiroyuki

    2006-05-15

    In order to evaluate influence of water on the pressure and transition interval of the olivine-wadsleyite transition, synthesis experiments were carried out in hydrous Forsterite90 composition at 9-16 GPa and 1273-1873 K. Three additional starting materials, representing (a) Mg2SiO4 (b) San-Carlos olivine (Fo89) and (c) CaO-MgO-Al2O3-FeO-SiO2 peridotite, were loaded in every experimental assembly simultaneously. We observed significant expansion of olivine + wadsleyite stability loop to the lower pressure for 2-3 GPa at 1473 K, whereas there was no significant shift of the phase transition boundary at 1873 K. These results are consistent with thermodynamic calculations made by Wood and inconsistent with recent experimental data by Chen et al. We report here preliminary results on water content of coexisting phases. Water solubility of olivine increases with pressure up to 0.15 wt.% H2O at 14 GPa. At 12-15 GPa H2O content of olivine is almost the same at temperatures from 1373 to 1773 K, whereas the H2O content of wadsleyite decreases from about 2.1 wt.% at 1373 K to 0.7 wt.% at 1773 K. We determined the partition coefficient of H2O between two phases. Dwd/ol is 11.8 at 1473 K, 7.2 at 1673 K and 4.5 at 1773 K. However if we apply recent calibration of H2O content in olivine by Bell et al. these Dwd/ol values are three times lower.

  7. Disclinations and grain boundary migration: evidence for a new deformation mechanism in olivine-rich rocks (Invited)

    NASA Astrophysics Data System (ADS)

    Cordier, P.; Demouchy, S. A.; Beausir, B.; Taupin, V.; Fressengeas, C.

    2013-12-01

    The rheology of olivine-rich rocks remains poorly understood. In particular, the ability of orthorhombic olivine to bear large strains represents an apparent violation of the von Mises criterion due to a lack of slip systems. In this study we show that a more general description of the deformation process including the motion of rotational defects referred to as disclinations can solve the olivine deformation paradox. Disclinations were proposed together with dislocations by Volterra (1907) to account for elastic distorsions (distorzione) in solids. They have recently been experimentally evidenced from orientation maps in several polycrystalline metallic alloys (Beausir & Fressengeas, 2013). Using high-resolution EBSD orientation maps we show that disclinations decorate grain boundaries in olivine samples deformed experimentally and in nature. We present a disclination-based model of a high-angle tilt boundary in olivine, which demonstrates that an applied shear induces grain boundary migration through disclination motion. This new approach allows further understanding of grain boundary-mediated plasticity in polycrystalline aggregates. By providing the missing mechanism for describing plastic flow in olivine, the present work allows multiscale modeling of the rheology of the upper mantle, from the atomic scale to the scale of the flow. Beausir, B. & Fressengeas, C., Disclination densities from EBSD orientation mapping. International Journal of Solids and Structures 50 (1), 137-146 (2013). Volterra, V., Sur l'équilibre des corps élastiques multiplement connexes. Annales scientifiques de l'École Normale Supérieure 24, 401-517 (1907). Acknowledgement for support: ERC grant RheoMan, Marie Curie fellowship PoEM and ANR NanoMec.

  8. Magnetic Susceptibility of Submicroscopic Metallic Iron Formation Through Laser Irradiation of Olivine

    NASA Astrophysics Data System (ADS)

    Markley, M. M.; Kletetschka, G.

    2014-12-01

    Surfaces of exposed solids change their integrity due to solar wind and micrometeorite impacts, resulting in significant modification of exposed mineral grains. Apart from the possibility of in-situ ice generation, initial iron rich composition allows for re-precipitation of iron. The importance of characterizing these SMFe (submicroscopic metallic iron) particles exists to better our interpretations in remote sensing of planetary surface minerals. For example, the presence of SMFe changes the spectral reflectance of silicate minerals in the visible (VIS) to near-infrared (NIR) wavelengths, and contributes to "space weathering": (1) SMFe darkens the overall reflectance, (2) steepens (or reddens) the spectral slope, and (3) decreases the contrast in the 1 µm band. Irradiating olivine samples with energies simulating micrometeorite impact energies revealed single domain (SD) and superparamagnetic (SPM) iron grains varying in size. All samples exhibit general VIS-NIR space weathering effects, but also magnetic anomalies in the immediate surface proximity and frequency dependent magnetic susceptibility changes due to the production of SMFe. Planetary minerals such as olivine produce more SMFe when micrometeorite impacts and/or solar wind irradiation increases. Magnetic textures found during the scanning of the laser irradiated samples reveal anomalies that are dominantly caused by metallic iron and are in superparamagnetic state while at room temperature. We observed an increased dispersion of these metallic anomalies when irradiation energy increased. Frequency dependent magnetic susceptibility measurements creates a data set that has potential to become a tool in remote detection of these surfaces by deep penetration radar incidence.

  9. Melt migration in a silicate liquid-olivine system - An experimental test of compaction theory

    NASA Technical Reports Server (NTRS)

    Riley, G. N., Jr.; Kohlstedt, D. L.; Richter, F. M.

    1990-01-01

    An experimentally derived melt migration profile is compared with those obtained from compaction theory. A couple is prepared in which a source-for-melt (a disk composed of a silicate glass and olivine) was placed in contact with a sink-for-melt (a disk of polycrystalline olivine) in order to induce melt migration under laboratory conditions. It is noted that melt infiltrates into the sink disk along triple junctions driven by capillary forces. In order to analyze the melt migration profile in terms of compaction theory, the equations developed by McKenzie (1984) to describe porous flow of a liquid in a deformable matrix were modified. The bouyancy force term is replaced with a capillary force term and governing equations are then solved numerically with the initial boundary conditions specified by the experimental design. Also, it is determined that compaction theory provides a good description of the experimental results provided that the permeability of these solid-liquid materials increases linearly with increasing liquid fraction.

  10. Pressure sensitivity of olivine slip systems and seismic anisotropy of Earth's upper mantle.

    PubMed

    Mainprice, David; Tommasi, Andréa; Couvy, Hélène; Cordier, Patrick; Frost, Daniel J

    2005-02-17

    The mineral olivine dominates the composition of the Earth's upper mantle and hence controls its mechanical behaviour and seismic anisotropy. Experiments at high temperature and moderate pressure, and extensive data on naturally deformed mantle rocks, have led to the conclusion that olivine at upper-mantle conditions deforms essentially by dislocation creep with dominant [100] slip. The resulting crystal preferred orientation has been used extensively to explain the strong seismic anisotropy observed down to 250 km depth. The rapid decrease of anisotropy below this depth has been interpreted as marking the transition from dislocation to diffusion creep in the upper mantle. But new high-pressure experiments suggest that dislocation creep also dominates in the lower part of the upper mantle, but with a different slip direction. Here we show that this high-pressure dislocation creep produces crystal preferred orientations resulting in extremely low seismic anisotropy, consistent with seismological observations below 250 km depth. These results raise new questions about the mechanical state of the lower part of the upper mantle and its coupling with layers both above and below. PMID:15716950

  11. Melt migration in a silicate liquid-olivine system: An experimental test of compaction theory

    SciTech Connect

    Riley, G.N. Jr.; Kohlstedt, D.L. ); Richter, F.M. )

    1990-11-01

    To investigate the kinetics of porous flow in partially molten peridotite, a melt migration couple - formed from a disc of fine-grained olivine plus {approximately}15% of a synthetic K-Al silicate glass and a disc of polycrystalline olivine - was heated at 1,255C under a confining pressure of 300 MPa for 2 hr. Driven by capillary forces, silicate liquid in the source disc infiltrates along three-grain junctions into the sink disc. To analyze the resulting melt migration profile in terms of compaction theory, the equations developed by McKenzie (1984) to describe porous flow of a liquid in a deformable matrix were modified by replacing the buoyancy force term with a capillary force term. The governing equations were then solved numerically with the governing equations were then solved numerically with the initial and boundary conditions specified by the experimental design. Comparison of the melt migration profile obtained from the experiment with those generated by numerical simulation demonstrates that compaction theory provides a good description of the experimental results provided that the permeability of these solid-liquid materials increases linearly with increasing liquid fraction.

  12. The effect of nonhydrostatic stress on the ??? and ??? olivine phase transformations

    NASA Astrophysics Data System (ADS)

    Green, Harry W., II; Young, Thomas E.; Walker, David; Scholz, Christopher H.

    The importance of phases with the composition (Mg,Fe)2SiO4 in the earth's upper mantle has led to great interest in the phase relations and mechanisms of transformation between the ? (olivine), ? (spinelloid) and ? (spinel) polymorphs of this system. The very high pressures of these transformations, however, has severely limited direct experimentation, hence several compounds that exhibit analogous transformations have been studied in order to infer the behavior of the mantle system. Such use of analogue materials can be a powerful approach but it carries with it the possibility of serious error because none of the systems available are completely analogous. Here, we use the microstructures exhibited by specimens of Mg2GeO4 to demonstrate how very faithfully this compound proxies for important nonhydrostatic stress effects in Mg-rich silicate olivine. In particular, both systems exhibit (i) martensitic and incoherent nucleation mechanisms for the ??? transformation, (ii) stress controlled anisotropy of nucleation and growth in densification transformations, and (iii) transformation-induced anticrack faulting. These results suggest that quantitative studies on carefully chosen analogues of other deep mantle phases can provide important insights into their mechanisms of transformation and rheology.

  13. The Mg2GeO4 olivine-spinel phase transition

    NASA Astrophysics Data System (ADS)

    Ross, Nancy L.; Navrotsky, Alexandra

    1987-09-01

    Enthalpies and entropies of transition for the Mg2GeO4 olivine-spinel transformation have been determined from self-consistency analyses of Dachille and Roy's (1960), Hensen's (1977) and Shiota et al.'s (1981) phase boundary studies. When all three data sets are analyzed simultaneously, ?H 973 and ?S 973 are constrained between -14000 to -15300 J mol-1 and -13.0 to -14.1·J mol-1 K-1, respectively. High-temperature solution calorimetric experiments completed on both polymorpha yield a value of -14046±1366 J mol-1 for ?H 973. Kieffer-type lattice vibrational models of Mg2GeO4 olivine and spinel based on newly-measured infrared and Raman spectra predict a value of -13.3±0.6 J mol-1 K-1 for ?S 1000. The excellent agreement between these three independent determinations of ?H and ?S suggests that the synthesis runs of Shiota et al. (1981) at high pressures and temperatures bracket equilibrium conditions. In addition, no configurational disorder of Mg and Ge was needed to obtain the consistent parameters quoted. The Raman spectrum and X-ray diffractogram show that little disorder, if any, is present in Mg2GeO4 spinel synthesized at 0.2 GPa and 973 1048 K.

  14. Anticrack-associated faulting at very high pressure in natural olivine

    NASA Astrophysics Data System (ADS)

    Green, Harry W.; Young, Thomas E.; Walker, David; Scholz, Christopher H.

    1990-12-01

    SHALLOW earthquakes are produced by brittle shear fracture of rock and/or fictional sliding on pre-existing fault surfaces1. At very high pressures, however, brittle fracture and frictional sliding are impossible because frictional resistance to movement on any potential fault surface is so great that ductile stress-relief processes accomodate strain at lower shear stresses than those necessary to activate faulting. Nevertheless, more than 20% of earthquakes with magnitudes greater than five occur at depths greater than 300km, where the pressure exceeds l0 GPa (ref. 2). Possible explanations for this paradox have been offered by several recent experimental studies of shearing instabilities associated with phase transformations at high 3-8. One of these mechanisms is associated with anticrack development during the olivine --> spinel (? --> ?) phase transformation in Mg2GeO4 at pressures of 1-2 GPa (refs 4-6) it is particularly attractive because it operates between mineral structures known to occur in the mantle. We show here that this mechanism also can operate in natural silicate olivine, (Mg,Fe)2SiO4, during onset of the ? --> ? transformation at the much higher pressures at which deep earthquakes occur. These results lend strong support to the hypothesis that the anticrack mechanism is responsible for such earthquakes4.

  15. Olivine cooling speedometers. [cooling rate indicator for lunar and terrestrial rock thermal histories

    NASA Technical Reports Server (NTRS)

    Onorato, P. I. K.; Uhlmann, D. R.; Taylor, L. A.; Coish, R. A.; Gamble, R. P.

    1978-01-01

    Several kinetic models of zoning in olivines are discussed at length. The effects on predicted cooling rates of various assumptions used in the analyses are evaluated. It is concluded that the models of Walker et al. (1977) and Taylor et al. (1977) both provide underestimates of the cooling rate required to preserve a given compositional profile, and that both models as well as the model of Taylor et al. (1978) can be used to provide order-of-magnitude estimates of cooling rates. A new model is described which considers diffusion in both solid and liquid during crystallization as well as diffusion in the solid after crystallization is complete. The model provides a description of the compositional gradients which develop during crystallization as well as after cooling at various rates. Applied to olivine crystals nucleated at 1272 C in a high-iron analogue to Lunar Composition 15555, the model predicts only slight compositional gradients - in accord with electron beam microprobe measurements on crystals grown isothermally at this temperature.

  16. State of stress in the lithosphere: Inferences from the flow laws of olivine

    USGS Publications Warehouse

    Kirby, S.H.

    1977-01-01

    The experimental flow data for rocks and minerals are reviewed and found to fit a law of the form {Mathematical expression} where {Mathematical expression} This law reduces to the familiar power-law stress dependency at low stress and to an exponential stress dependency at high stress. Using the material flow law parameters for olivine, stress profiles with depth and strain rate are computed for a representative range of temperature distributions in the lithosphere. The results show that the upper 15 to 25 km of the oceanic lithosphere must behave elastically or fail by fracture and that the remainder deforms by exponential law flow at intermediate depths and by power-law flow in the rest. A model computation of the gravitational sliding of a lithospheric plate using olivine rheology exhibits a very sharp decoupling zone which is a consequence of the combined effects of increasing stress and temperature on the flow law, which is a very sensitive function of both. ?? 1977 Birkha??user Verlag.

  17. Carbon solubility in olivine and the mode of carbon storage in the Earth's mantle.

    PubMed

    Keppler, Hans; Wiedenbeck, Michael; Shcheka, Svyatoslav S

    2003-07-24

    The total amount of carbon in the atmosphere, oceans and other near-surface reservoirs is thought to be negligible compared to that stored in the Earth's mantle. Although the mode of carbon storage in the mantle is largely unknown, observations of microbubbles on dislocations in minerals from mantle xenoliths has led to the suggestion that carbon may be soluble in silicates at high pressure. Here we report measurements of carbon solubility in olivine, the major constituent of the upper mantle, at pressures up to 3.5 GPa. We have found that, contrary to previous expectations, carbon solubility in olivine is exceedingly low--of the order of 0.1 to 1 parts per million by weight. Together with similar data for pyroxenes, garnet and spinel, we interpret this to imply that most carbon must be present as a separate phase in the deeper parts of the upper mantle, probably as a carbonate phase. Large-scale volcanic eruptions tapping such a carbonate-bearing mantle reservoir might therefore rapidly transfer large amounts of carbon dioxide into the atmosphere, consistent with models that link global mass extinctions to flood basalt eruptions via a sudden increase in atmospheric carbon dioxide levels. PMID:12879066

  18. In-situ X-ray Synchrotron Microtomography: Real Time Pore Structure Evolution during Olivine Carbonation

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Fusseis, F.; Lisabeth, H. P.; Xiao, X.

    2013-12-01

    Mineral carbonation has been proposed as a promising method for long-term, secure sequestration of carbon dioxide. In porous rocks, fluid-rock interactions can significantly alter the pore space and thus exert important controls over the rate and extent of carbonation. We constructed an x-ray transparent pressure cell [Fusseis et al., 2013] to investigate the real time pore structure evolution during mineral carbonation in porous olivine aggregates. In each experiment, a sintered olivine sample was subjected to a confining pressure of 13 MPa and a pore pressure of 10 MPa, with a sodium bicarbonate solution (NaHCO3 at 1.5 M) as pore fluid. At these pressure conditions, the cell was heated to 473 K. Constant pressure and temperature conditions were maintained during the length of the experiments, lasting 72-120 hours. Using a polychromatic beam in the 2-BM upstream hutch at the Advanced Photon Source, 3-dimensional (3-D) microtomography data were collected in 20 seconds with 30-minute interval. A novel phase retrieval reconstruction algorithm [Paganin et al., 2002] was used to reconstruct microtomographic datasets with a voxel size of ~1.1 micron. The microtomography images at different stages of the carbonation process reveal progressive growth of new crystals in the pore space. Integration of a x-ray transparent pressure vessel with flow through capacity and 3-D microtomography provides a novel research direction of studying the coupled chemo-hydro-thermal-mechanical processes in rocks.

  19. Solubility of Cr, Ti, and Al in co-existing olivine, spinel, and liquid at 1 atm

    NASA Technical Reports Server (NTRS)

    Akella, J.; Williams, R. J.; Mullins, O.

    1976-01-01

    The partitioning of chromium between olivines, spinels and silicate liquids was studied as a function of temperature, oxygen fugacity, and cooling rate between 1175 and 1300 C and redox states near the Fe-FeO buffer. It is found that the weight ratio of Cr2O3 in olivine to that in the liquid increases slightly as oxygen fugacity decreases, but the effect is very small. The cooling experiments showed that the Cr2O3 content does not re-equilibrate with cooling.

  20. Microstructures of olivine-plagioclase corona in meta-ultramafic rocks from Sefuri Mountains, NW Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Ikeda, T.; Nishiyama, T.; Yamada, S.; Yanagi, T.

    2007-09-01

    Two types of reaction rims occur between olivine and plagioclase in ultramafic rocks from the Sefuri Mountains, NW Kyushu, Japan, which were metamorphosed under granulite-facies conditions. One occurs as a thin film of orthopyroxene along the boundary between olivine and plagioclase (orthopyroxene zone). The other is composed of two zones: symplectite of calcic amphibole and spinel on the plagioclase-side (symplectite zone) and calcic amphibole with sporadic orthopyroxene on the olivine-side (tremolite zone). In the tremolite zone, calcic amphibole shows a systematic decrease in Al content and increase in Mg/(Fe +Mg) with decreasing distance from olivine. Local equilibria maintained during the diffusion-controlled corona-forming reaction enable us to apply equilibrium thermodynamics to calcic amphibole and adjacent orthopyroxene. An integrated formulation of the Gibbs method for an Fe-Mg exchange reaction constrains the equilibrium temperature recorded in the tremolite zone to be 600-710 °C. It is significantly lower than the temperature of the granulite-facies metamorphism (800-900 °C) estimated using conventional geothermobarometry. Except for H 2O, the association of calcic amphibole and spinel in the symplectite zone is chemically equivalent to the association of olivine, plagioclase and orthopyroxene that was stable before the corona formation. This suggests that the following orthopyroxene-consuming reaction describes the paragenetic change taking place between 800-900 °C and 600-710 °C, olivine + plagioclase + orthopyroxene + aqueous fluid = calcic amphibole + spinel. In contrast, the overall reaction inferred from microstructures produces orthopyroxene as well as calcic amphibole and spinel at the expense of olivine and plagioclase. This reaction requires removal mainly of MgO that is also responsible for destabilizing the local association of olivine and plagioclase. These features suggest that the presence of orthopyroxene as a product in the corona is not always indicative of an orthopyroxene-producing reaction being responsible for the change of paragenetic relation. Microstructural features should be carefully applied to infer the reaction describing paragenetic change by which we argue the P- T path of the rocks.

  1. Bacterial Oxidation of Iron in Olivine: Implications for the Subsurface Biosphere, Global Chemical Cycles, and Life on Mars

    NASA Astrophysics Data System (ADS)

    Fisk, M. R.; Popa, R.; Smith, A. R.; Popa, R.; Boone, J.

    2011-12-01

    We isolated 21 species of bacteria from subseafloor and terrestrial basalt environments and which thrive on olivine at neutral pH. Cell numbers increase four to five orders of magnitude over three weeks in media where the only metabolic energy comes from the oxidation of Fe(II) in olivine. The subseafloor bacteria were isolated from a borehole on the flank of Juan de Fuca Ridge in the northeast Pacific basin where the temperature ranged from 4 up to 64 °C over four years. Terrestrial isolates originated from the basalt-ice boundary in a lava tube on the flank of Newberry Caldera in the Cascades of Oregon. The borehole water was either seawater or seawater plus subseafloor formation water and the lava tube ice was frozen meteoric or ground water. Although microorganisms capable of oxidizing iron for growth are known, microbes that oxidize iron from silicate minerals at neutral pH have not previously been cultured. The 21 species in this study are the first neutrophilic, iron-oxidizing bacteria (nFeOB) to be isolated and cultured that grow on olivine. These nFeOB are primary producers and we believe that they are a widespread component of the subsurface biosphere. In addition to their ability use iron from olivine, these microbes assimilate carbon from bicarbonate in solution and can grow when oxygen pressures are low. They also use nitrate as an alternative electron acceptor to oxygen in anaerobiosis. Since basalt is the most common rock in the Earth's crust and iron is the fourth most abundant element in the crust, we believe nFeOB are likely to be a significant portion of the subsurface biosphere. They are likely to affect, and perhaps in some environments control, the weathering rate of olivine and possibly of pyroxene and basalt glass. Olivine is a component of Mars's surface and it is present on other rocky bodies in the solar system. The ability of these bacteria to use Fe(II) from olivine, to assimilate carbon, to grow at low temperature, and to use low levels of oxygen and nitrate as oxidants would allow them to survive below the surface of Mars. These cultured organisms, which are the first known to oxidize iron from olivine at neutral pH, may be a major component of the subsurface biosphere, may affect global chemical cycles of elements in basalt, and could potentially, live in the Martian subsurface.

  2. Geobarometry of ultramafic xenoliths from Loihi Seamount, Hawaii, on the basis of CO2 inclusions in olivine

    USGS Publications Warehouse

    Roedder, E.

    1983-01-01

    Abundant fluid inclusions in olivine of dunite xenoliths (???1-3 cm) in basalt dredged from the young Loihi Seamount, 30 km southeast of Hawaii, are evidence for three coexisting immiscible fluid phases-silicate melt (now glass), sulfide melt (now solid), and dense supercritical CO2 (now liquid + gas)-during growth and later fracturing of some of these olivine crystals. Some olivine xenocrysts, probably from disaggregation of xenoliths, contain similar inclusions. Most of the inclusions (2-10 ??m) are on secondary planes, trapped during healing of fractures after the original crystal growth. Some such planes end abruptly within single crystals and are termed pseudosecondary, because they formed during the growth of the host olivine crystals. The "vapor" bubble in a few large (20-60 ??m), isolated, and hence primary, silicate melt inclusions is too large to be the result of simple differential shrinkage. Under correct viewing conditions, these bubbles are seen to consist of CO2 liquid and gas, with an aggregate ??{variant} = ??? 0.5-0.75 g cm-3, and represent trapped globules of dense supercritical CO2 (i.e., incipient "vesiculation" at depth). Some spinel crystals enclosed within olivine have attached CO2 blebs. Spherical sulfide blebs having widely variable volume ratios to CO2 and silicate glass are found in both primary and pseudosecondary inclusions, demonstrating that an immiscible sulfide melt was also present. Assuming olivine growth at ??? 1200??C and hydrostatic pressure from a liquid lava column, extrapolation of CO2 P-V-T data indicates that the primary inclusions were trapped at ??? 220-470 MPa (2200-4700 bars), or ??? 8-17 km depth in basalt magma of ??{variant} = 2.7 g cm-3. Because the temperature cannot change much during the rise to eruption, the range of CO2 densities reveals the change in pressure from that during original olivine growth to later deformation and rise to eruption on the sea floor. The presence of numerous decrepitated inclusions indicates that the inclusion sample studied is biased by the loss of higher-density inclusions and suggests that some part of these olivine xenoliths formed at greater depths. ?? 1983.

  3. Composition of komatiite melts from Abitibi and Belingwe inferred from melt inclusions in olivine phenocrysts.

    NASA Astrophysics Data System (ADS)

    Asafov, Evgeny; Sobolev, Alexander; Arndt, Nicholas; Batanova, Valentina

    2015-04-01

    Komatiites are the products of extreme amounts of partial melting and hence are best indicators of the composition of their mantle sources. However, the most known komatiites are highly altered, and this prevents the use of their compositions to estimate the volatile and mobile element contents of the mantle. To estimate the concentrations of these elements, we analyzed melt inclusions in high-Mg olivine phenocrysts from two 2.7 Ga sample suites, one from Abitibi greenstone belt, Canada and the other from the Belingwe greenstone belt, Zimbabwe. Fresh olivine grains 0.2-0.5 mm across were heated for 5 minutes and quenched at 1350°C in a C-O-H atmosphere with oxygen fugacity corresponding to quartz-fayalite-magnetite buffer. Homogenized melt inclusions were exposed at the surface of grains and analyzed by electron probe micro-analyzer for concentrations of Mg, Si, Ti, Al, Fe, Mn, Ca, Na, Cr, P, K, Cl and S. The size of melt inclusions ranges from 20 to 80 µm. The measured compositions were adjusted to equilibrium with host olivine with iron loss correction using Petrolog3 software (Danyushevsky & Plechov, G-cubed 12, 2011). Cracked inclusions were filtered out using their low S contents. Data on the volatile components Cl and S were thus obtained for the first time for the melt inclusions in Abitibi komatiites. Calculated melt compositions range from 19.5 to 27.1 wt.% MgO in Abitibi samples and from 18.9 to 22 wt.% in Belingwe samples. Other elements, except Cl and K, show strong negative correlation with MgO and follow an olivine fractionation trend. Concentrations of Si, Ti, Al, and Ca are consistent with the corresponding compositions of whole rocks. Variations of Cl and K cannot be explained by fractionation of olivine and are attributed to the variations in parental melt. The melt inclusion compositions from Abitibi and Belingwe komatiites have similar Ca, Na, K and S concentrations at the same concentration of Mg but Al and Ti are lower in Belingwe samples, and Si and Cl are higher. In Abitibi samples, Cl correlates strongly with K2O with a constant ratio (Cl/K2O= 0.7); in Belingwe samples the correlation is weak with Cl/K2O=1.4. In general, Cl/K2O ratios are a factor of 10-20 higher than in estimated Phanerozoic mantle reservoirs. Possible explanations of obtained data including crustal contamination of parental melt; presence of recycled components in the mantle sources or specific composition of Archean mantle sources will be discussed. This study has been founded by Russian Science Foundation grant 14-17-00491.

  4. Are CI Chondrites Cometary Samples? A Search for Olivine and Use as a Discrimination Index.

    NASA Astrophysics Data System (ADS)

    Le Gac, Y.; Kearsley, A. T.; Bland, P. A.; Russell, S. S.

    2009-04-01

    CI chondrites are among the most unusual type of carbonaceous chondrites. There are only five CI1 meteorite falls. They are heavily altered (BULLOCK et al., 2005), yet show a similar bulk composition to the solar photosphere (ANDERS and GREVESSE, 1989; LODDERS, 2003). There still remains uncertainties about the origin and formation of the parent bodies for such meteorites. One theory is that CI chondrites derive from cometary nuclei, based on evidence from textural and mineralogical arguments (CAMPINS and SWINDLE, 1998) and orbital parameters (GOUNELLE et al., 2006). We now have known cometary material to compare to CI chondrites. The NASA sample return mission Stardust returned to Earth on January 2006. This mission collected cometary dust particles by flying through the coma of comet 81P/Wild 2. The Preliminary Examination (Science, 314, 2006) and subsequent studies (MaPS, 43, 2008), showed that expected hydrated minerals seem to be absent. This may in part be because finer-grained hydrated minerals are less likely to survive the collection process (ISHII et al., 2008) although experimental studies (BURCHELL et al., 2006; NOGUCHI et al., 2007) have shown that coarser (> m) phyllosilicates can survive capture under conditions analogous to the Stardust encounter. To determine the relationship between CIs and returned cometary material, we may therefore have to focus on the distinctive composition of anhydrous minerals, which are rare in CI meteorites. Olivine is a common mineral in the solar system, and has been reported in diverse compositions within Stardust samples, especially with distinctive levels of Fe, Cr and Mn. In cold cometary bodies it is unlikely that the chemical composition of olivine will have been affected by parent body processing, so olivines are likely to be unaltered and could provide evidence for any primary genetic link between CIs and cometary material. In this study we present an optimised analytical technique to detect micrometer-sized olivine grains in large area searches of the matrix of CI chondrites, locating the sparse grains, which can then be characterised by microanalysis (Electron Microprobe, TEM, TOF-SIMS). We then compare CI olivine compositions with Stardust ones, in order to distinguish any genetic link. References: ANDERS E. and GREVESSE N. (1989) Abundances of the elements - Meteoritic and solar. Geochimica et Cosmochimica Acta 53, 197-214. BULLOCK E. S., GOUNELLE M., LAURETTA D. S., GRADY M. M. and RUSSELL S. S. (2005) Mineralogy and texture of Fe-Ni sulfides in CI1 chondrites: Clues to the extent of aqueous alteration on the CI1 parent body. Geochimica et Cosmochimica Acta 69, 2687-2700. BURCHELL M. J., GRAHAM G. and KEARSLEY A. (2006) Cosmic Dust Collection in Aerogel. Annual Review of Earth and Planetary Sciences 34, 385-418. CAMPINS H. and SWINDLE T. D. (1998) Expected characteristics of cometary meteorites. Meteoritics & Planetary Science 33, 1201-1211. GOUNELLE M., SPURNY, PAVEL and BLAND P. A. (2006) The orbit and atmospheric trajectory of the Orgueil meteorite from historical records. Meteoritics & Planetary Science 41, 135-150. ISHII H. A., BRADLEY J. P., DAI Z. R., CHI M., KEARSLEY A. T., BURCHELL M. J., BROWNING N. D. and MOLSTER F. (2008) Comparison of Comet 81P/Wild 2 Dust with Interplanetary Dust from Comets. Science 319(5862), 447-450. LODDERS K. (2003) Solar System Abundances and Condensation Temperatures of the Elements. Astrophysical Journal 591, 1220-1247. NOGUCHI T., NAKAMURA T., OKUDAIRA K., YANO H., SUGITA S. and BURCHELL M. J. (2007) Thermal alteration of hydrated minerals during hypervelocity capture to silica aerogel at the flyby speed of Stardust. Meteoritics and Planetary Science 42, 357-372.

  5. Deducing Wild 2 Components with a Statistical Dataset of Olivine in Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Frank, D. R.; Zolensky, M. E.; Le, L.

    2012-01-01

    Introduction: A preliminary exam of the Wild 2 olivine yielded a major element distribution that is strikingly similar to those for aqueously altered carbonaceous chondrites (CI, CM, and CR) [1], in which FeO-rich olivine is preferentially altered. With evidence lacking for large-scale alteration in Wild 2, the mechanism for this apparent selectivity is poorly understood. We use a statistical approach to explain this distribution in terms of relative contributions from different chondrite forming regions. Samples and Analyses: We have made a particular effort to obtain the best possible analyses of both major and minor elements in Wild 2 olivine and the 5-30 micrometer population in chondrite matrix. Previous studies of chondrite matrix either include larger isolated grains (not found in the Wild 2 collection) or lack minor element abundances. To overcome this gap in the existing data, we have now compiled greater than 10(exp 3) EPMA analyses of matrix olivine in CI, CM, CR, CH, Kakangari, C2-ungrouped, and the least equilibrated CO, CV, LL, and EH chondrites. Also, we are acquiring TEM/EDXS analyses of the Wild 2 olivine with 500s count times, to reduce relative errors of minor elements with respect to those otherwise available. Results: Using our Wild 2 analyses and those from [2], the revised major element distribution is more similar to anhydrous IDPs than previous results, which were based on more limited statistics (see figure below). However, a large frequency peak at Fa(sub 0-1) still persists. All but one of these grains has no detectable Cr, which is dissimilar to the Fa(sub 0-1) found in the CI and CM matrices. In fact, Fa(sub 0-1) with strongly depleted Cr content is a composition that appears to be unique to Kakangari and enstatite (highly reduced) chondrites. We also note the paucity of Fa(sub greater than 58), which would typically indicate crystallization in a more oxidizing environment [3]. We conclude that, relative to the bulk of anhydrous IDPs, Wild 2 may have received a larger contribution from the Kakangari and/or enstatite chondrite forming regions. Alternatively, Wild 2 may have undergone accretion in an anomalously reducing region, marked by nebular condensation of this atypical forsterite. In [4], a similar conclusion was reached with an Fe-XANES study. We will also use similar lines of reasoning, and our previous conclusions in [5], to constrain the relative contributions of silicates that appear to have been radially transported from different ordinary and carbonaceous chondrite forming regions to the Kuiper Belt. In addition, the widespread depletion of Cr in these FeO-rich (Fa(sub greater than 20)) fragments is consistent with mild thermal metamorphism in Wild 2.

  6. Olivine Hydration and Carbonation Reactions in Porous Open Systems: Insights from Reactive Percolation Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Godard, M.; Peuble, S.; Gouze, P.; Andreani, M.; Luquot, L.

    2013-12-01

    Hydrothermal exchanges between fluids (seawater, hydrothermal and mantle-derived CO2-rich fluids) and mantle-dominated lithosphere at ridges represent a major means of mass exchange between the mantle and the Earth's envelopes. It results from/in a suite of strongly interconnected thermal, mineralogical, and (bio-) chemical processes within the seafloor, that contributes to the Earth's carbon budget through carbonation reactions (dissolution of silicates and precipitation of carbonates) and the production of complex carbon compounds. Recent experimental studies were realized to constrain the chemical parameters controlling these reactions (pH, T, kinetics, catalysis), one of the main applications being the development of techniques for geological storage of excess atmospheric CO2 into ultramafic ophiolitic massifs and in basaltic reservoirs. However, although these reactions will occur only if fluids can flow through the reacting rocks, the mechanisms controlling the hydrodynamic properties of the system during hydration and carbonation reactions remain poorly constrained. We present the results of three sets of percolation-reaction experiments during which CO2-depleted to CO2-saturated fluids were injected into olivine cores, dunitic samples and magmatic olivine with trace basalts. These experiments allowed us to explore the role of the initial mineralogy and structure of rocks, the composition of fluids (pCO2...) and flow rate and their effects on hydrodynamic properties and carbonation/hydration efficiency. The experiments produced broadly similar results, i.e. dissolution of olivine (× mafic minerals and glass when present), precipitation of carbonates and of serpentine type minerals and a steady decrease in permeability with time. In details, differences in the compositions of the fluids and of the reaction products were observed from one set of experiments to the other as well as in the rate at which chemical and permeability changes occurred during the experiments: (i) during the earliest stages of the reactions, Ca-Mg-(Fe-)rich carbonates precipitate in low flow zones while Si-rich layer develop at olivine surface in higher flow zones, which provide a transient mechanism maintaining constant permeability; (ii) porosity changes are small and permeability decrease is triggered mainly by the precipitation of serpentine-type minerals at the expense of olivine, in low flow zones and/or downstream; (iii) carbonation efficiency at the scale of porous samples is controlled to the first order by feedback effects between flow rate, local pCO2 and the kinetics of (catalyzed) hydration reactions. These experiments show that reactions are controlled at pore scale, which results in the development of chemical microenvironments and of mineralogical, chemical and hydrodynamic heterogeneities at the scale of the samples. The spatial distribution of mixing, triggered by the variability of the velocity field in pores, controls the occurrence and the rate of reactions and must be taken into account to model the efficiency and the sustainability of carbonation in these environments.

  7. Deformation fabrics of olivine in Val Malenco peridotite found in Italy and implications for the seismic anisotropy in the upper mantle

    E-print Network

    Jung, Haemyeong

    Deformation fabrics of olivine in Val Malenco peridotite found in Italy and implications peridotite Upper mantle Water An exhumed huge body of ultramafic rocks is preserved in Val Malenco, Italy. In this study, petrofabrics and deformation microstructures of olivine in the Val Malenco peridotite were

  8. Lattice-preferred orientation of olivine found in diamond-bearing garnet peridotites in Finsch, South Africa and implications for seismic

    E-print Network

    Jung, Haemyeong

    Lattice-preferred orientation of olivine found in diamond-bearing garnet peridotites in Finsch in the upper mantle provides important constraints on mantle dynamics, continental evolution and global for the pressure-induced LPO of natural olivine because samples from the deep upper mantle are rare and often

  9. THERMAL INFRARED SPECTROSCOPY OF A SYNTHETIC OLIVINE SERIES (FORSTERITE-FAYALITE) AND INTERPRETATION OF THE NILI FOSSAE, SYRTIS MAJOR, AND ISIDIS REGIONS

    E-print Network

    Hiroi, Takahiro

    THERMAL INFRARED SPECTROSCOPY OF A SYNTHETIC OLIVINE SERIES (FORSTERITE- FAYALITE the solid solution series between Mg2SiO4 (forsterite [Fo100]) to Fe2SiO4 (fayalite [Fo0]). Changes. Synthetic olivine samples, ranging in composition from forsterite to fayalite [1], have been analyzed us

  10. Lunar highland rocks - Element partitioning among minerals. II - Electron microprobe analyses of Al, P, Ca, Ti, Cr, Mn and Fe in olivine

    NASA Technical Reports Server (NTRS)

    Smith, J. V.; Hansen, E. C.; Steele, I. M.

    1980-01-01

    Lunar olivines from anorthosites, granulitic impactites, and rocks in the Mg-rich plutonic trend were subjected to electron probe measurements for Al, P, Ca, Ti, Cr and Mn, which show that the FeO/MnO ratio for lunar olivines lies between 80 and 110 with little difference among the rock types. The low values of Ca in lunar olivines indicate slow cooling to subsolidus temperatures, with blocking temperatures of about 750 C for 67667 and 1000 C for 60255,73-alpha determined by the Finnerty and Boyd (1978) experiments. An important paradox is noted in the low Ti content of Fe-rich olivines from anorthosites, although both Ti and Fe tend to become enriched in liquid during fractional distillation. Except for Ca and Mn, olivine from anorthosites has lower minor element values than other rock types. Formation from a chemically distinct system is therefore implied.

  11. P-V-T-X evolution of olivine-hosted melt inclusions during high-temperature homogenization treatment

    NASA Astrophysics Data System (ADS)

    Schiavi, Federica; Provost, Ariel; Schiano, Pierre; Cluzel, Nicolas

    2016-01-01

    During low-high temperature (T) cycles imposed on olivine-hosted melt inclusions (MIs) we observe a systematic increase in homogenization temperature (Th) with time, regardless of their initial major-element and H2O contents. Bubble persistence at high T suggests that inclusion internal pressure (Pint) is lower than its original, trapping pressure. We explore how reversible and irreversible processes modify the composition (X), volume (V) and Pint of heated MIs, and compare the results of theoretical modeling with experimental observations of MIs from FAMOUS Zone (FZ, Mid-Atlantic Ridge) and La Sommata (SOM, Vulcano, Aeolian Islands) basaltic samples. Due to olivine dissolution at inclusion walls and thermoelastic deformation, Pint-V-X conditions change significantly upon heating. Olivine dissolution induces changes in major-element composition (i.e., enrichment in Fe and Mg), morphology and volume (up to +25% at 1500 °C). We provide equations for the thermoelastic deformation of olivine bearing a two-phase, liquid-gas inclusion for the end-member cases of chemical equilibrium and no exchange between gas and liquid. These equations allow Pint-V evolution to be related to variations in bubble volume fraction. Upon heating, both Pint and V variations are smaller in the presence of a gas bubble than for a homogeneous liquid inclusion, at the same T. Dissolution-reprecipitation and thermoelastic deformation of the olivine host are reversible processes, so initial Pint-V-X conditions are restored upon cooling. On the contrary, water loss from MIs and plastic deformation of the olivine host are processes that irreversibly lower Pint, and account for the systematic increase of Th with time. Our theoretical and experimental investigations suggest that the increase of Th in volatile-rich SOM MIs is mainly related to progressive release of water. Compared to larger MIs located at a similar distance from the olivine rim, smaller MIs show a faster increase in Th with time, consistent with the effects of diffusive water loss. Nonetheless, we cannot exclude the combined effect of incipient plastic deformation, which would enhance water loss by diffusion along dislocations. The increase in Th in volatile-poor FZ MIs is driven mainly by elasto-plastic deformation of the olivine host, which becomes more marked with increasing T and decreased distance from MI wall to olivine rim. Occurrence of plastic deformation in FZ olivines is testified by dislocation patterns observed around inclusions. In general, conducting homogenization experiments at 1 atm prevents MI homogenization happening at a Th equal to entrapment T. This is due to a drop in Pint caused by the elastic deformation that affects olivine phenocrysts bearing pressurized MIs during magma ascent. Predicted increase in Th ranges from a few degrees to tens of degrees depending on entrapment conditions, melt composition and volatile contents.

  12. Volatile Systematics of the Icelandic Mantle from Olivine-Hosted Melt Inclusions

    NASA Astrophysics Data System (ADS)

    Miller, W. G. R.; Maclennan, J.; Thordarson, T.

    2014-12-01

    The behaviour of volatiles within a volcanic system can tell us about melt storage depths, melt evolution, and degassing processes. It is therefore important to be able to quantify the amount of each volatile species entering the system. Olivine-hosted melt inclusions can provide compositions of the primitive mantle melt entering volcanic systems. In some cases they have been unaffected by processes such as melt mixing, fractional crystallisation and degassing; so chemical variations are source signatures. With the knowledge that volatiles behave as very incompatible elements, and with measured volatile/trace-element ratios, we can estimate volatile concentrations within the Icelandic mantle source. Abundances of CO2, H2O, Cl, F, S and trace elements have been measured by SIMS for over 100 olivine-hosted (Fo87.8-88.6) melt inclusions from Kistufell, a monogenic subglacial eruption known to have elevated 3He/4He (15.5 R/Ra)[1] and situated above the inferred locus of the Icelandic mantle plume. H2O concentrations in the melt inclusions are near uniform and similar to that of the carrier glass (0.10-0.15 wt%), likely due to diffusive equilibration through the olivine host at low pressure. CO2 shows more variation, ranging from 1200 to 0ppm, probably from a combination of melt heterogeneity and degassing. The majority of melt inclusions are incompatible trace element-depleted (La/Yb = 1.3), indicating that they were probably generated by high fraction melting of a depleted source in the shallow mantle. The CO2/Nb ratio of this source mantle is ~308, very similar to that of Borgarhraun, ~314[2], which has a lower 3He/4He ratio (12.2 R/Ra)[3]. This CO2/Nb ratio, along with H2O/Ce ~200 and F/Nd ~18, are consistent with other measured melt inclusion suites from Iceland, suggesting limited volatile/trace-element ratio variation within the Icelandic depleted melt source. By analysing more eruptions across Iceland, we hope to identify any spatial variations in volatile/trace-element ratios within the Icelandic mantle. [1] K. Breddam (2002) J. Petrology 43, 2, 345-373; [2] E. H. Hauri (2002) Goldschmidt Abstract; [3] C. Macpherson et al (2005) EPSL 233,411-427.

  13. Deformation of Olivine at Subduction Zone Conditions Determined from In situ Measurements with Synchrotron Radiation

    SciTech Connect

    H Long; D Weidner; L Li; J Chen; L Wang

    2011-12-31

    We report measurements of the deformation stress for San Carlos olivine at pressures of 3-5 GPa, temperatures of 25-1150 C, and strain rates of 10{sup -7}-10{sup -5} s{sup -1}. We determine a deformation stress of approximately 2.5 GPa that is relatively temperature and strain rate independent in the temperature range of 400-900 C. The deformation experiments have been carried out on a deformation DIA (D-DIA) apparatus, Sam85, at X17B2, NSLS. Powder samples are used in these experiments. Enstatite (MgSiO{sub 3}) (3-5% total quality of sample) is used as the buffer to control the activity of silica. Ni foil is used in some experiments to buffer the oxygen fugacity. Water content is confirmed by IR spectra of the recovered samples. Samples are compressed at room temperature and are then annealed at 1200 C for at least 2 h before deformation. The total (plastic and elastic) strains (macroscopic) are derived from the direct measurements of the images taken by X-ray radiograph technique. The differential stresses are derived from the diffraction determined elastic strains. In the regime of 25-400 C, there is a small decrease of stress at steady state as temperature increases; in the regime of 400 C to the 'transition temperature', the differential stress at steady state ({approx}2.5 GPa) is relatively insensitive to the changes of temperature and strain rate; however, it drastically decreases to about 1 GPa and becomes temperature-dependent above the transition temperature and thereafter. The transition temperature is near 900 C. Above the transition temperature, the flow agrees with power law creep measurements of previous investigations. The anisotropy of differential stress in individual planes indicates that the deformation of olivine at low temperature is dominated by [0 0 1](1 0 0). Accounting to a slower strain rate in the natural system, the transition temperature for the olivine in the slab is most likely in the range of 570-660 C.

  14. Olivine or impact melt: Nature of the “Orange” material on Vesta from Dawn

    NASA Astrophysics Data System (ADS)

    Le Corre, Lucille; Reddy, Vishnu; Schmedemann, Nico; Becker, Kris J.; O'Brien, David P.; Yamashita, Naoyuki; Peplowski, Patrick N.; Prettyman, Thomas H.; Li, Jian-Yang; Cloutis, Edward A.; Denevi, Brett W.; Kneissl, Thomas; Palmer, Eric; Gaskell, Robert W.; Nathues, Andreas; Gaffey, Michael J.; Mittlefehldt, David W.; Garry, William B.; Sierks, Holger; Russell, Christopher T.; Raymond, Carol A.; De Sanctis, Maria C.; Ammanito, Eleonora

    2013-11-01

    NASA’s Dawn mission observed a great variety of colored terrains on asteroid (4) Vesta during its survey with the Framing Camera (FC). Here we present a detailed study of the orange material on Vesta, which was first observed in color ratio images obtained by the FC and presents a red spectral slope. The orange material deposits can be classified into three types: (a) diffuse ejecta deposited by recent medium-size impact craters (such as Oppia), (b) lobate patches with well-defined edges (nicknamed “pumpkin patches”), and (c) ejecta rays from fresh-looking impact craters. The location of the orange diffuse ejecta from Oppia corresponds to the olivine spot nicknamed “Leslie feature” first identified by Gaffey (Gaffey, M.J. [1997]. Icarus 127, 130-157) from ground-based spectral observations. The distribution of the orange material in the FC mosaic is concentrated on the equatorial region and almost exclusively outside the Rheasilvia basin. Our in-depth analysis of the composition of this material uses complementary observations from FC, the visible and infrared spectrometer (VIR), and the Gamma Ray and Neutron Detector (GRaND). Several possible options for the composition of the orange material are investigated including, cumulate eucrite layer exposed during impact, metal delivered by impactor, olivine-orthopyroxene mixture and impact melt. Based on our analysis, the orange material on Vesta is unlikely to be metal or olivine (originally proposed by Gaffey (Gaffey, M.J. [1997]. Icarus 127, 130-157)). Analysis of the elemental composition of Oppia ejecta blanket with GRaND suggests that its orange material has ?25% cumulate eucrite component in a howarditic mixture, whereas two other craters with orange material in their ejecta, Octavia and Arruntia, show no sign of cumulate eucrites. Morphology and topography of the orange material in Oppia and Octavia ejecta and orange patches suggests an impact melt origin. A majority of the orange patches appear to be related to the formation of the Rheasilvia basin. Combining the interpretations from the topography, geomorphology, color and spectral parameters, and elemental abundances, the most probable analog for the orange material on Vesta is impact melt.

  15. Rapid olivine and pyroxene weathering in volcanic plume during the Mount Etna pyroclastic activity (2001)

    NASA Astrophysics Data System (ADS)

    Antonella Randazzo, Loredana; Andò, Sergio; Censi, Paolo; Zuddas, Pierpaolo; Garzanti, Eduardo

    2010-05-01

    Mt. Etna is the most active volcano in Europe and a continuous source of pyroclastic products. In summer 2001 began the most spectacular Etna's eruptive activity in the last 300 years producing an impressive eruptive plume with several million of m3 of volcanic ejecta. Samples of ash collected during the falling of pyroclastic material were separated with sodium metatungstate. Heavy and light fractions have recovered and mounted on slides for optical observations. Selected olivine and pyroxenes were hand-picked and mounted on a stub to Scanning Electron Microscopy observations. On the same minerals Raman spectra spectrum analysis were carried out, both to confirm their chemical nature and to analyse the possible relationship between crystallographic orientation of different faces and dissolution features. Observations at different scales reveal, on selected minerals surfaces, the presence of common corrosion features such as grooves, each pits and irregular shapes with signs of favoured dissolution on particular areas. Chemical analyses carried out by Raman and EDS, confirm the chemical nature of olivine and augite and highlight an intense weathering on particular crystals faces, according to specific crystallographic direction, that is parallel to c axes, in correspondence of cleavages and rim intersection. In particular we have observed well developed etch pits and saw termination in clinopyroxenes, mainly on (001) and (111) faces. Moreover clinopyroxenes have got smooth or not so deeply corroded surfaces on the prismatic faces: (100);(110);(010). Olivines have shown a deeply corrosion on oblique faces respect the c axis and well preserved surfaces, without signs of corrosion, on the prismatic faces parallel to c axis. We interpret these structures as index of chemical and physical alteration processes whose minerals are subject in the volcanic plume, before interaction with seawater or weathering on land. In particular there are clear dissolution features in minerals sites where cations (Ca2+ and Mg2+) can be easily extracted by Cl- and F- into the plume and where cleavages interact, that is in (001) face, in which we can see typical alteration forms such as "sawteeth". The alteration process is thus anisotropic since minerals are undergone to a selective attack on their surface. Knowledge about morphological and chemical features and the dissolution degree of minerals just after their emission, takes a relevant importance if we consider the following environmental dynamics, such as minerals-seawater interactions. In fact it allow us to well understanding the minerals dissolution behaviour and the following trace metal release in marine system.

  16. Atom Probe Tomography and Visible/Near-Infrared Spectral Analysis of Simulated Solar Wind Hydrogen Implanted Olivine

    NASA Astrophysics Data System (ADS)

    Kuhlman, K. R.; Poplawsky, J. D.; Hiroi, T.; Baba, K.

    2015-07-01

    We present the results of the first atom probe tomography (APT) and visible/near-infrared (VNIR) spectral study of a sample of San Carlos olivine (Fo90.1) exposed to simulated space weathering due to hydrogen at solar wind energy (~1keV/amu).

  17. Reply to comment by Nozaka (2014) on “Dehydration breakdown of antigorite and the formation of B-type olivine CPO”

    NASA Astrophysics Data System (ADS)

    Nagaya, Takayoshi; Wallis, Simon R.; Kobayashi, Hiroaki; Michibayashi, Katsuyoshi; Mizukami, Tomoyuki; Seto, Yusuke; Miyake, Akira; Matsumoto, Megumi

    2014-12-01

    We would like to thank Dr. Nozaka for his interest in our work and also for supplying some of the crystal orientation data that we used in our study. He presents a detailed discussion of differences in interpretation between our two studies. The main difference is whether the strong B-type olivine CPO developed as a result of topotactic static growth after breakdown of antigorite (Nagaya et al., 2014) or if it developed due to homoepitaxial growth on a limited number of olivine grains that already showed a general B-type CPO (Nozaka, 2014). In both of our studies static growth of olivine due to the breakdown of antigorite is key in the strengthening or formation of B-type olivine CPO. This conclusion has potentially far reaching implications for the interpretation of mantle seismic anisotropy in subduction zones and is the most important take home message. However, the details of interpretation are also important. In our reply, we focus on what we consider to be the 5 main points of disagreement. We refer to Fig. 1 to explain different microstructural domains.

  18. Single-crystal Brillouin Spectroscopy with Laser Heating and Variable q: Design, Demonstration and New Results on Olivine

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Bass, J. D.

    2014-12-01

    We have developed a novel Brillouin spectroscopy system integrated with CO2 laser heating and Raman spectroscopic capabilities. High-pressure laser heating experiments on liquid water compressed in a diamond-anvil cell up to 2500 ± 150 K demonstrate the flexibility and performance of the system. Temperature is determined from the grey-body thermal radiation of the heated samples,. New single-crystal laser heating Brillouin measurements were made on San Carlos Olivine in the (111) plane at pressures up to ~13 GPa, and T~1300 ± 200 K. We obtain quantitative values for the thermal pressure in the diamond cell. Using KCl and KBr and pressure-transmitting media, we show that pressure gradients in the sample chamber are small at high P-T conditions based on observations of the olivine-wadsleyite transition. This system is additionally designed for continuously varying scattering angles from near forward scattering (0º scattering angle) up to near back scattering (~141º). Our results on the sound velocities of olivine at high pressure-temperature conditions have implications for the nature of the 410 km discontinuity and the olivine content of the upper mantle.

  19. Physics of the Earth and Planetary Interiors 141 (2004) 253267 Stresses along the metastable wedge of olivine in a subducting

    E-print Network

    Gable, Carl W.

    2004-01-01

    Physics of the Earth and Planetary Interiors 141 (2004) 253­267 Stresses along the metastable wedge Physics, University of California, Los Angeles, CA 90095, USA b Earth and Environmental Sciences Division calculation of the stresses associated with changes in volume during phase transitions of olivine

  20. Noble gas systematics for coexisting glass and olivine crystals in basalts and dunite xenoliths from Loihi Seamount

    USGS Publications Warehouse

    Kaneoka, I.; Takaoka, N.; Clague, D.A.

    1983-01-01

    Noble gas isotopes including 3He 4He, 40Ar 36Ar and Xe isotope ratios were determined for coexisting glass and olivine crystals in tholeiitic and alkalic basalts and dunite xenoliths from Loihi Seamount. Glass and coexisting olivine crystals have similar 3He 4He ratios (2.8-3.4) ?? 10-5, 20 to 24 times the atmospheric ratio (RA), but different 40Ar 36Ar ratios (400-1000). Based on the results of noble gas isotope ratios and microscopic observation, some olivine crystals are xenocrysts. We conclude that He is equilibrated between glass and olivine xenocrysts, but Ar is not. The apparent high 3He 4He ratio (3 ?? 10-5; = 21 RA) coupled with a relatively high 40Ar 36Ar ratio (4200) for dunite xenoliths (KK 17-5) may be explained by equilibration of He between MORB-type cumulates and the host magma. Except for the dunite xenoliths, noble gas data for these Loihi samples are compatible with a model in which samples from hot spot areas may be explained by mixing between P (plume)-type and M (MORB)-type components with the addition of A (atmosphere)-type component. Excess 129Xe has not been observed due to apparent large mass fractionation among Xe isotopes. ?? 1983.