Effect of water on the fluorine and chlorine partitioning behavior between olivine and silicate melt     

Bastian?JoachimEmail authorView author&#;s OrcID profile  André?Stechern  Thomas?Ludwig  Jürgen?Konzett  Alison?Pawley  Lorraine?Ruzié-Hamilton  Patricia?L.?Clay  Ray?Burgess  Christopher?J.?Ballentine 《Contributions to Mineralogy and Petrology》2017,172(4):15

Halogens show a range from moderate (F) to highly (Cl, Br, I) volatile and incompatible behavior, which makes them excellent tracers for volatile transport processes in the Earth’s mantle. Experimentally determined fluorine and chlorine partitioning data between mantle minerals and silicate melt enable us to estimate Mid Ocean Ridge Basalt (MORB) and Ocean Island Basalt (OIB) source region concentrations for these elements. This study investigates the effect of varying small amounts of water on the fluorine and chlorine partitioning behavior at 1280?°C and 0.3 GPa between olivine and silicate melt in the Fe-free CMAS+F–Cl–Br–I–H₂O model system. Results show that, within the uncertainty of the analyses, water has no effect on the chlorine partitioning behavior for bulk water contents ranging from 0.03 (2) wt% H₂O (D_Cl ^ol/melt = 1.6?±?0.9 × 10^?4) to 0.33 (6) wt% H₂O (D_Cl ^ol/melt = 2.2?±?1.1 × 10^?4). Consequently, with the effect of pressure being negligible in the uppermost mantle (Joachim et al. Chem Geol 416:65–78, 2015), temperature is the only parameter that needs to be considered for the determination of chlorine partition coefficients between olivine and melt at least in the simplified iron-free CMAS+F–Cl–Br–I–H₂O system. In contrast, the fluorine partition coefficient increases linearly in this range and may be described at 1280?°C and 0.3 GPa with (R ²?=?0.99): \(D_{F}^{\text{ol/melt}}\ =\ 3.6\pm 0.4\ \times \ {{10}^{-3}}\ \times \ {{X}_{{{\text{H}}_{\text{2}}}\text{O}}}\left( \text{wt }\!\!\%\!\!\text{ } \right)\ +\ 6\ \pm \ 0.4\times \,{{10}^{-4}}\). The observed fluorine partitioning behavior supports the theory suggested by Crépisson et al. (Earth Planet Sci Lett 390:287–295, 2014) that fluorine and water are incorporated as clumped OH/F defects in the olivine structure. Results of this study further suggest that fluorine concentration estimates in OIB source regions are at least 10% lower than previously expected (Joachim et al. Chem Geol 416:65–78, 2015), implying that consideration of the effect of water on the fluorine partitioning behavior between Earth’s mantle minerals and silicate melt is vital for a correct estimation of fluorine abundances in OIB source regions. Estimates for MORB source fluorine concentrations as well as chlorine abundances in both mantle source regions are within uncertainty not affected by the presence of water.  相似文献   

Experimental boron isotope fractionation between tourmaline and fluid: confirmation from in situ analyses by secondary ion mass spectrometry and from Rayleigh fractionation modelling     

Horst R. Marschall  Christian Meyer  Bernd Wunder  Thomas Ludwig  Wilhelm Heinrich 《Contributions to Mineralogy and Petrology》2009,158(5):675-681

Tourmaline synthesised in an experiment with low boron excess was analysed in situ by secondary ion mass spectrometry. It revealed significant B isotope zonation with ¹¹B/¹⁰B ratios increasing in the growth direction of the crystals. Trend, magnitude and absolute values strongly support results from high-B-excess isotope fractionation experiments. Furthermore, the closed system B-isotopic evolution of the experimental fluid was modelled by Rayleigh fractionation. The model results are in excellent agreement with the measured B-isotope composition of the run-product fluid. Consequently, low-element-excess experiments are proposed as an ideal approach to determine fluid-solid isotope fractionation factors for systems that are characterised by Rayleigh fractionation.  相似文献   

Modelling the poroelasticity of rocks and ice   总被引：1，自引：0，他引：1  

Thomas Keller  Uwe Motschmann  & Ludwig Engelhard 《Geophysical Prospecting》1999,47(4):509-526

For many geophysical and astrophysical applications the relationship between physical bulk properties and porosity is needed. As part of the preparation for the 'Rosetta' comet rendezvous mission, a simple model for the porosity dependence of the elastic properties of granular media, i.e. the elastic moduli and the propagation velocities of elastic waves, has been developed based on textural properties and the contact stiffness of the constituent particles. It is shown that the derived relationships fit very well with sandstone data. The model is also consistent with data for snow and ice and is in agreement with the transformation mechanisms from snow to ice. A short review shows the relevance to another physical bulk property, the thermal conductivity.  相似文献   

Hemispherical asymmetries in sunspot areas and auroral frequencies     

Ludwig Schlamminger 《Solar physics》1991,135(2):407-413

One thousand and fifty-two aurorae boreales and 554 aurorae australes recorded during the nineteenth century at medium latitudes 55° N or 55° S are compared statistically with the known hemispherical asymmetry of the sums of the areas of sunspots. According to the present study, the solar hemispherical asymmetry may be accompanied by an analogous pattern of the hemispherical frequency of auroral days. For the number of auroral days in each hemisphere beyond the two auroral ovals, a remarkable degree of phase equality with the sunspot areas during the second Gleissberg cycle can be demonstrated.  相似文献   

Hydrogen incorporation in orthopyroxene: interaction of different trivalent cations     

Roland?StalderEmail author  Stephan?Klemme  Thomas?Ludwig  Henrik?Skogby 《Contributions to Mineralogy and Petrology》2005,150(5):473-485

The incorporation of hydrogen into ferrosilite, Fe-bearing enstatite and orthopyroxene containing different trivalent cations (Cr³⁺ and Al³⁺, Cr³⁺ and Fe³⁺) was investigated experimentally at 25 kbar. Hydrogen concentration was determined by FTIR-spectroscopy on oriented crystal sections and by secondary ion mass spectroscopy, whereas Mößbauer spectroscopy and optical spectroscopy were used to characterise the valence state of Fe in orthopyroxene. Results suggest that hydrogen incorporation in ferrosilite is achieved by a similar mechanism as in pure enstatite. In Cr-bearing samples, however, hydrogen incorporation is reduced by the presence of other trivalent cations by an increased tendency to form Tschermaks substitutions, e.g. Si _T ⁴⁺ + Mg _M1 ²⁺ ? Al _T ³⁺ + Cr _M1 ³⁺ . Thus, hydrogen solubility in natural orthopyroxenes from the Earth’s mantle, containing significant amounts of Cr³⁺, Al³⁺, and Fe³⁺, may be much more limited than expected from their trivalent cation content, as a large fraction of the trivalent cations does not participate in H-incorporating reactions as 2 Mg _M1 ²⁺ ? M _M1 ³⁺ + V_M1 + H _i ⁺ .  相似文献   

Evolution of a tourmaline-bearing lawsonite eclogite from the Elekdağ area (Central Pontides,N Turkey): evidence for infiltration of slab-derived B-rich fluids during exhumation   总被引：3，自引：0，他引：3  

Rainer?AltherrEmail author  Gültekin?Topuz  Horst?Marschall  Thomas?Zack  Thomas?Ludwig 《Contributions to Mineralogy and Petrology》2004,148(4):409-425

An undated high-pressure low-temperature tectonic mélange in the Elekda area (central Pontides, N Turkey) comprises blocks of MORB-derived lawsonite eclogite within a sheared serpentinite matrix. In their outer shells, some of the eclogite blocks contain large (up to 6 cm) tourmaline crystals. Prograde inclusions in poikiloblastic garnet from a well-preserved eclogite block are lawsonite, epidote/clinozoisite, omphacite, rutile, glaucophane, chlorite, Ba-bearing phengite, minor actinolite, winchite and quartz. In addition, glaucophane, lawsonite and rutile occur as inclusions in omphacite. These inclusion assemblages document the transition from a garnet-lawsonite-epidote-bearing blueschist to a lawsonite eclogite with the peak assemblage garnet + omphacite I + lawsonite + rutile. Peak metamorphic conditions are not well-constrained but are estimated approximately 400–430°C and >1.35 GPa, based on Fe–Mg exchange between garnet and omphacite and the coexistence of lawsonite + omphacite + rutile. During exhumation of the eclogite–serpentinite mélange in the hanging wall of a subduction system, infiltration of B-rich aqueous fluids into the rims of eclogite blocks caused retrogressive formation of abundant chlorite, titanite and albite, followed by growth of tourmaline at the expense of chlorite. At the same time, omphacite I (X_Jd=0.24–0.44) became unstable and partially replaced by omphacite II characterized by higher X_Jd (0.35–0.48), suggesting a relatively low silica activity in the infiltrating fluid. Apart from Fe-rich rims developed at the contact to chlorite, tourmaline crystals are nearly homogeneous. Their compositions correspond to Na-rich dravite, perhaps with a small amount of excess (tetrahedral) boron (~5.90 Si and 3.10 B cations per 31 anions). ¹¹ B values range from –2.2 to +1.7. The infiltrating fluids were most probably derived from subducting altered oceanic crust and sediments.  相似文献   

Einige Messungen zum Wärmehaushalt poikilohydrer Flechten und Moose     

Otto Ludwig Lange 《Theoretical and Applied Climatology》1954,5(2):182-190

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Harvesting strategies for a randomly fluctuating population   总被引：2，自引：0，他引：2  

Ludwig  Donald 《ICES Journal of Marine Science》1980,39(2):168-174

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Bestimmung der optischen Natur durchsichtiger Einschlußkörper,entwickelt am Fluorit     

Dr. Ludwig Stegmüller 《Contributions to Mineralogy and Petrology》1952,3(3):186-192

Ohne Zusammenfassung  相似文献   

Status of the physics of substellar objects project     

H. R. A. Jones  S. Viti  J. Tennyson  B. Barber  G. Harris  J. C. Pickering  R. Blackwell‐Whitehead  J.‐P. Champion  F. Allard  P. H. Hauschildt  U. G. Jorgensen  P. Ehrenfreund  E. Stachowska  H.‐G. Ludwig  E. L. MartÍn  Ya. Pavlenko  Yu. Lyubchik  R. L. Kurucz 《Astronomische Nachrichten》2005,326(10):920-924

A full understanding of the properties of substellar objects is one of the major challenges facing astrophysics. Since their discovery in 1995, hundreds of brown dwarfs and extrasolar planets have been discovered. While these discoveries have enabled important comparisons with theory, observational progress has been much more rapid than the theoretical understanding of cool atmospheres. The reliable determination of mass, abundances, gravities and temperatures is not yet possible. The key problem is that substellar objects emit their observable radiation in the infrared region of the spectrum where our knowledge of atomic, molecular and line broadening data is poor. Here we report on the status of our PoSSO (Physics of SubStellar Objects) project. In order to understand brown dwarfs and extrasolar planets increasing more like those in our solar system, we are studying a wide range of processes. Here we give an update on the project and sketch an outline of atoms, molecules and processes requiring study. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献