Coupled U-Pb Dating and Hf Isotopic Analysis of Detrital Zircon of Modern River Sand From the Yalu River (YarlungTsangpo) Drainage System in Southern Tibet:Constraints on the Transport Processes and Evolution of Himalayan Rivers     

ZHANG Jinyu  YIN An  LIU Wencan  WU Fuyuan  DING Lin  GROVE Marty 《《地质学报》英文版》2013,87(Z1):102-102

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Adsorption of xenon ions onto defects in organic surfaces: Implications for the origin and the nature of organics in primitive meteorites     

Yves Marrocchi  Bernard Marty  François Robert 《Geochimica et cosmochimica acta》2011,75(20):6255-6266

Noble gases trapped in primitive meteorites are quantitatively hosted by a poorly defined organic phase, labeled phase Q. Xenon is enriched in heavy isotopes by +1.30 ± 0.06% per atomic mass unit (amu, 1σ) in phase Q relative to solar. To understand the origin of this fractionation, we have performed adsorption experiments of xenon atoms and ions, ionized in a radiofrequency plasma. Within the reaction vessel, anthracite was heated and the resulting smoke deposited onto the walls of the vessel, resulting in carbon-rich films. Xenon was trapped in the carbon films either as ions in the ionization zone of the vessel, or as neutral atoms outside this zone. Xenon trapped as ionic Xe is tightly bound and is enriched by +1.36 ± 0.05%/amu (1σ) in heavy isotopes, reproducing the isotopic fractionation of xenon trapped in phase Q relative to solar. Neutral xenon is more loosely trapped, is in much lower concentration, and is not isotopically fractionated. Ionized conditions allow the constant xenon isotopic composition observed in meteorite during stepwise heating release to be reproduced. Furthermore, the trapping efficiency of Xe⁺ estimated from these experiments is consistent with the high xenon concentration measured in phase Q of primitives meteorites.Xenon was not trapped in the film by implantation because the energies of the incident Xe atoms and ions were far too low (<1 eV). From the difference of behavior between ionic and neutral forms, we propose that xenon ions were trapped via chemical bonding at the surface of the newly created C-rich film. The observed mass-dependent fractionation of xenon is unlikely to have occurred in the gas phase. It is more probably related to variations in chemical bonding strengths of Xe isotopes as chemical bonds involving heavy Xe isotopes are more stable than those involving light ones. For young stars, including the young Sun, photons emitted in the far UV energy range able to ionize noble gases (<100 nm) were orders of magnitude more abundant than for the Present-day Sun, allowing efficient ionization of gaseous species. A way to achieve Q-noble gas fractionation and trapping was UV irradiation by nearby young stars from O/B association of the surface of growing organic grains in the outer part of the solar system or by the young Sun at the edge of the disk.  相似文献   

Segregating gas from melt: an experimental study of the Ostwald ripening of vapor bubbles in magmas     

Nicole C. Lautze  Thomas W. Sisson  Margaret T. Mangan  Timothy L. Grove 《Contributions to Mineralogy and Petrology》2011,161(2):331-347

Diffusive coarsening (Ostwald ripening) of H₂O and H₂O-CO₂ bubbles in rhyolite and basaltic andesite melts was studied with elevated temperature–pressure experiments to investigate the rates and time spans over which vapor bubbles may enlarge and attain sufficient buoyancy to segregate in magmatic systems. Bubble growth and segregation are also considered in terms of classical steady-state and transient (non-steady-state) ripening theory. Experimental results are consistent with diffusive coarsening as the dominant mechanism of bubble growth. Ripening is faster in experiments saturated with pure H₂O than in those with a CO₂-rich mixed vapor probably due to faster diffusion of H₂O than CO₂ through the melt. None of the experimental series followed the time^1/3 increase in mean bubble radius and time⁻¹ decrease in bubble number density predicted by classical steady-state ripening theory. Instead, products are interpreted as resulting from transient regime ripening. Application of transient regime theory suggests that bubbly magmas may require from days to 100 years to reach steady-state ripening conditions. Experimental results, as well as theory for steady-state ripening of bubbles that are immobile or undergoing buoyant ascent, indicate that diffusive coarsening efficiently eliminates micron-sized bubbles and would produce mm-sized bubbles in 10²–10⁴ years in crustal magma bodies. Once bubbles attain mm-sizes, their calculated ascent rates are sufficient that they could transit multiple kilometers over hundreds to thousands of years through mafic and silicic melt, respectively. These results show that diffusive coarsening can facilitate transfer of volatiles through, and from, magmatic systems by creating bubbles sufficiently large for rapid ascent.  相似文献   

Melts of garnet lherzolite: experiments, models and comparison to melts of pyroxenite and carbonated lherzolite   总被引：2，自引：2，他引：0  

Timothy L. Grove  Eva S. Holbig  Jay A. Barr  Christy B. Till  Michael J. Krawczynski 《Contributions to Mineralogy and Petrology》2013,166(3):887-910

Phase equilibrium experiments on a compositionally modified olivine leucitite from the Tibetan plateau have been carried out from 2.2 to 2.8 GPa and 1,380–1,480 °C. The experiments-produced liquids multiply saturated with spinel and garnet lherzolite phase assemblages (olivine, orthopyroxene, clinopyroxene and spinel ± garnet) under nominally anhydrous conditions. These SiO₂-undersaturated liquids and published experimental data are utilized to develop a predictive model for garnet lherzolite melting of compositionally variable mantle under anhydrous conditions over the pressure range of 1.9–6 GPa. The model estimates the major element compositions of garnet-saturated melts for a range of mantle lherzolite compositions and predicts the conditions of the spinel to garnet lherzolite phase transition for natural peridotite compositions at above-solidus temperatures and pressures. We compare our predicted garnet lherzolite melts to those of pyroxenite and carbonated lherzolite and develop criteria for distinguishing among melts of these different source types. We also use the model in conjunction with a published predictive model for plagioclase and spinel lherzolite to characterize the differences in major element composition for melts in the plagioclase, spinel and garnet facies and develop tests to distinguish between melts of these three lherzolite facies based on major elements. The model is applied to understand the source materials and conditions of melting for high-K lavas erupted in the Tibetan plateau, basanite–nephelinite lavas erupted early in the evolution of Kilauea volcano, Hawaii, as well as younger tholeiitic to alkali lavas from Kilauea.  相似文献   

X-ray and γ-ray spectra and variability of the black hole candidate GX 339–4     

Grzegorz Wardzi&#;ski  rzej A. Zdziarski  Marek Gierli&#;ski  J. Eric Grove  Keith Jahoda  W. Neil Johnson 《Monthly notices of the Royal Astronomical Society》2002,337(3):829-839

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Investigating the nexus of climate,energy, water,and land at decision-relevant scales: the Platform for Regional Integrated Modeling and Analysis (PRIMA)     

Ian Kraucunas  Leon Clarke  James Dirks  John Hathaway  Mohamad Hejazi  Kathy Hibbard  Maoyi Huang  Chunlian Jin  Michael Kintner-Meyer  Kerstin Kleese van Dam  Ruby Leung  Hong-Yi Li  Richard Moss  Marty Peterson  Jennie Rice  Michael Scott  Allison Thomson  Nathalie Voisin  Tristram West 《Climatic change》2015,129(3-4):573-588

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Some principles of data storage and information retrieval and their implications for information exchange     

J. A. Gilliland  G. Grove 《Mathematical Geology》1973,5(1):1-10

The definition of objectives and question of interpretation must be considered when setting up data banks. The objective will determine the type of data to be collected. A hierarchy of data-processing systems exists where the amount of interpretation in the data increases as the order of the system increases. The remarkable continuity of basic data can be embodied in the axiom: Any fundamental data free of interpretation cannot be discontinuous. The measurement of space and time remain invariant for all orders of data systems and are essential for relating data containing various amounts of interpretation. In general, only basic data should be exchanged. Where this is not feasible the object described should be clearly defined in space and time.  相似文献   

Modified passive capillary samplers for collecting samples of snowmelt infiltration for stable isotope analysis in remote,seasonally inaccessible watersheds 2: field evaluation     

Marty D. Frisbee  Fred M. Phillips  Andrew R. Campbell  Jan M. H. Hendrickx  Emily M. Engle 《水文研究》2010,24(7):834-849

Twelve modified passive capillary samplers (M‐PCAPS) were installed in remote locations within a large, alpine watershed located in the southern Rocky Mountains of Colorado to collect samples of infiltration during the snowmelt and summer rainfall seasons. These samples were collected in order to provide better constraints on the isotopic composition of soil‐water endmembers in the watershed. The seasonally integrated stable isotope composition (δ¹⁸O and δ²H) of soil‐meltwater collected with M‐PCAPS installed at shallow soil depths < 10 cm was similar to the seasonally integrated isotopic composition of bulk snow taken at the soil surface. However, meltwater which infiltrated to depths > 20 cm evolved along an isotopic enrichment line similar to the trendline described by the evolution of fresh snow to surface runoff from snowmelt in the watershed. Coincident changes in geochemistry were also observed at depth suggesting that the isotopic and geochemical composition of deep infiltration may be very different from that obtained by surface and/or shallow‐subsurface measurements. The M‐PCAPS design was also used to estimate downward fluxes of meltwater during the snowmelt season. Shallow and deep infiltration averaged 8·4 and 4·7 cm of event water or 54 and 33% of the measured snow water equivalent (SWE), respectively. Finally, dominant shallow‐subsurface runoff processes occurring during snowmelt could be identified using geochemical data obtained with the M‐PCAPS design. One soil regime was dominated by a combination of slow matrix flow in the shallow soil profile and fast preferential flow at depth through a layer of platy, volcanic rocks. The other soil regime lacked the rock layer and was dominated by slow matrix flow. Based on these results, the M‐PCAPS design appears to be a useful, robust methodology to quantify soil‐water fluxes during the snowmelt season and to sample the stable isotopic and geochemical composition of soil‐meltwater endmembers in remote watersheds. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Rethinking the nature of urban environmental politics: Security, subjectivity, and the non-human     

Kevin Grove 《Geoforum》2009,40(2):207-216

The growing field of urban political ecology (UPE) has greatly advanced understandings of the socio-ecological transformations through which urban economies and environments are produced. However, this field has thus far failed to fully consider subjective (and subject-forming) dimensions of urban environmental struggle. I argue that this can be overcome through bringing urban political ecology into conversation with both post-structural political ecology and critical geopolitics. Bridging these literatures focuses attention on practices of socio-ecological exclusion and attachment through which environmental subjectivities are formed. This argument is drawn out through a case study of the politics of local economic development and conservation within the watershed of the Big Darby Creek near Columbus, Ohio. This struggle was driven by a preservationist movement that coalesced around a shared understanding of socio-ecological hybridity as a source of metaphysical insecurity. Hybridity appears here as a site of political and ethical struggle over social and ecological exclusions produced in the pursuit of security. This case study demonstrates a paradox of environmental politics: the non-human is at once a site of constituent possibilities for identity and subjectivity as well as forces which seek to foreclose this radical openness. Recognizing the paradoxical nature of environmental struggle allows for a more complex and nuanced account of the multifarious forces that shape the formation of environmental subjectivities.  相似文献   

AuPdFe ternary solution model and applications to understanding the fO2 of hydrous, high-pressure experiments     

Jay A. Barr  Timothy L. Grove 《Contributions to Mineralogy and Petrology》2010,160(5):631-643

This study provides an experimental calibration of the equilibrium constant for AuPdFe alloys with Fe-bearing silicate melts. The ideal metal capsules for H₂O-bearing experiments are pure Au, because of its slow hydrogen diffusivity. However, above the melting point of Au, other materials must be used. The solution to this problem is to use AuPd alloy capsules. However, under most relevant fO₂ conditions, this alloy absorbs Fe from the coexisting silicate melt, thus changing the bulk composition of the experimental charge. This study combines previous work on the Au–Pd, Pd–Fe, and Au–Fe binary systems to develop a ternary thermodynamic solution model for AuPdFe. This solution model is used with experiments to calculate an equilibrium reaction coefficient for the FeO_melt → Fe_alloy + 1/2O₂ exchange reaction. Using a non-ideal ternary solution model, the fO₂ conditions of hydrous, piston cylinder experiments can be estimated by analyzing the sample capsule alloy and the coexisting liquid composition.  相似文献