Co-existing fluid and silicate inclusions in mantle diamond   总被引：1，自引：0，他引：1  

E.L. Tomlinson  A.P. Jones  J.W. Harris 《Earth and Planetary Science Letters》2006,250(3-4):581-595

We document the compositions of co-existing silicate macro-inclusions and fluid micro-inclusions in the fibrous coats of eight coated diamonds from the Panda kimberlite (Canada). The mineral inclusions in the diamond coats come from either the peridotite suite (Cr-pyrope, orthopyroxene, olivine and Cr-diopside) or the eclogite suite (omphacite). Therefore, fibrous diamonds grow in the same paragenetic environments as octahedral diamonds. The inclusions document a more fertile source composition (lower Mg# and higher CaO) than for equivalent phases in octahedral diamonds from Panda and worldwide. However, moderate to high Cr₂O₃ contents in garnet and clinopyroxene inclusions suggest that this apparent fertility is due to a secondary process. Geothermometry of the silicate inclusions yields low equilibration temperatures of 930 to 1010 °C. The co-existing fluid micro-inclusions are dominated by H₂O, carbonate and KCl. Fluid inclusions in both the peridotitic and eclogitic samples fall along linear arrays between Fe–Ca–Mg carbonate and KCl. Inclusions in the one eclogitic sample also contain quartz. We suggest that the diamonds have trapped both metasomatised minerals and the metasomatic fluid, and so provide a snap shot of a metasomatic event in the mantle.  相似文献   

Circumstellar disks and planetary formation     

Rodger I. Thompson  Peter A. Strittmatter 《Earth, Moon, and Planets》1978,19(2):207-210

The role of circumstellar disks in star and planetary formation is briefly reviewed. The observed disk around MWC 349 is used as an example and a table of evolutionary time scales and parameters is presented. The disk about MWC 349 is characteristic of that expected about a massive star. Disk structure about solar mass stars is more completely reviewed by Cameron (1978). The parameters for the disk indicate that there is a deduced region where conditions are appropriate for dust condensation and possible aggregation of material to planetary masses. For the purposes of the discussion we are assuming that the infrared as well as optical radiation arises from the disk which extends the known extent of the disk to 10¹⁴cm. It is not yet certain that this is the case.Paper presented at the Conference on Protostars and Planets, held at the Planetary Science Institute, University of Arizona, Tucson, Arizona, between January 3 and 7, 1978.  相似文献   

Deliberate omission or unfortunate oversight: Should stygofaunal surveys be included in routine groundwater monitoring programs?     

Moya Tomlinson  Andrew J. Boulton  Peter J. Hancock  Peter G. Cook 《Hydrogeology Journal》2007,15(7):1317-1320

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Galaxy Evolution in the Northern HDF     

Rodger I. Thompson 《Astrophysics and Space Science》2002,281(1-2):445-448

The history of star formation in the Northern Hubble Deep Field is probed using a combination of optical and near infrared images taken with WFPC2 and NICMOS on the Hubble Space Telescope. These images cover more than a factor of five in wavelength. This broad wavelength coverage allows accurate photometric determinations of redshift, extinction and intrinsic spectral energy distribution for each galaxy. From these parameters the star formation rate for each galaxy is determined by relating the 1500 angstrom flux to the net star formation rate. We then correct the rates at high redshift for the effects of surface brightness dimming by using a standard form of the star formation intensity distribution. Our measurements show that the star formation rate in the Northern HDF is roughly constant from a redshift of 1 through 6. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

The determination of α-amino acids in seawater using a fluorimetric analyser     

Rodger Dawson  Richard Gary Pritchard 《Marine Chemistry》1978,6(1):27-40

A method is described for the detection of free α-amino acids in the picomole range in seawater samples of less than 100 ml volume. The modifications made to a standard amino acid analyser to incorporate a fluorimetric detection system are described in detail, together with the methods for desalting the seawater samples on cation exchange resin and the concentration procedures prior to analysis. A complete analysis of up to 30 amino acids requires around 3 h with a detection limit of around 0.05 μg of an individual acid per litre. Twenty samples of seawater from different depths in the open Baltic have been analysed for their FAA contents together with 3 samples taken from the Kiel Fjord. The total FAA content of the samples ranges from 4.5 to 84 μg/l with a mean of around 25 μg/l. Five samples were hydrolysed prior to analysis in order to estimate the CAA content of the seawater. The values lay in the range 438–805 μg/l.  相似文献   

HST Imaging of an Old Galaxy Group at Z=1.55     

Andrew J. Bunker  Hyron Spinrad  Ross McLure  Arjun Dey  James Dunlop  John Peacock  Daniel Stern  Rodger Thompson  Ian Waddington  Rogier Windhorst 《Astrophysics and Space Science》2002,281(1-2):527-528

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The GRIS     

Rodger I. Thompson 《Experimental Astronomy》1994,3(1-4):193-194

The GRIS is a prism cross-dispersed spectrometer utilizing a NICMOS 3 detector array for moderate and high dispersion spectroscopy in the near infrared spectral region. The spectrometer is cryogenically cooled with liquid nitrogen and operates on the 2.3 m Steward Observatory Telescope. Initial use proves it to be an excellent tool for near infrared astrophysics.  相似文献   

Radar Campaign to Determine the Dependence of Initial Radii of Meteor Plasma Trains on Trajectory and Orbit     

W. J. Baggaley  G. E. Plank  L. Tomlinson  J. Grant 《Earth, Moon, and Planets》2004,95(1-4):663-669

Experimental and theoretical work on the transverse dimensions of meteoric plasma trains have not converged to provide generally accepted values especially uncertain is the dependence of the train radii on meteor speeds. The roles of the meteoroid structure, fragmentation and plasma processes such as ion–electron instabilities need establishing. Knowledge of the quantitative spatial distribution of plasma in meteor trains is essential for a correct interpretation of fluxes and orbital characteristics. A current project is described which employs the AMOR 26 MHz radar facility in conjunction with a frequency managed radar operating at longer wavelengths designed to measure the ionization train radii, heights, atmospheric speeds and orbits of individual meteors.  相似文献   

Performance of grass and eucalyptus riparian buffers in a pasture catchment,Western Australia,part 1: riparian hydrology     

Lucy A. McKergow  Ian P. Prosser  David M. Weaver  Rodger B. Grayson  Adrian E. Reed 《水文研究》2006,20(11):2309-2326

Rainfall takes many flowpaths to reach a stream, and the success of riparian buffers in water quality management is significantly influenced by riparian hydrology. This paper presents results from hydrometric monitoring of riparian buffer hydrology in a pasture catchment. Runoff processes and riparian flowpaths were investigated on two planar hillslopes with regenerating grass and E. globulus buffers. Surface runoff and subsurface flows (A‐ and B‐horizons) were measured for 3 years using surface runoff collectors, subsurface troughs and piezometers. Water volumes moving through the riparian buffers via the measured flowpaths were ranked B‐horizon ? surface runoff ≈ A‐horizon. Runoff volumes through the B‐horizon troughs were an order of magnitude greater than those recorded for the most productive surface runoff plots or the A‐horizon troughs. Subsurface runoff and saturation‐excess overland flow (SOF) were limited to the winter months, whereas infiltration‐excess overland flow (IEOF) can occur all year round during intense storms. Surface runoff was recorded on 33 occasions, mostly during winter (late May–early October), and total annual surface runoff volumes collected by the 20 unconfined (2 m wide) runoff plots varied between > 80 and < 20 m³. Subsurface flow only occurred in winter, and the 6 m wide B‐horizon subsurface troughs flowed above 1 l s^?1 continuously, whereas the A‐horizon troughs flowed infrequently (<6 days per year). In summer, surface runoff occurred as IEOF during intense storms in the E. globulus buffer, but not in the grass buffer. Observations suggest that surface crusting reduced the soil's infiltration capacity in the E. globulus buffer. During winter, SOF and seepage were observed in both buffers, but subsurface flow through the B‐horizon was the dominant flowpath. Key hydrologic differences between the grass and tree buffers are the generation of IEOF in the E. globulus buffer during intense summer storms, and the smaller subsurface runoff volumes and fewer flow days in the E. globulus buffer. Low surface runoff volumes are likely to limit the potential of these buffers to filter pollutants from surface runoff. High subsurface flow volumes and saturated conductivities are also likely to limit the residence time of water in the subsurface domain. Based on their hydrologic performance, the key roles of riparian buffers in this landscape are likely to be displacing sediment and nutrient‐generating activities away from streams and stabilizing channel morphology. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Performance of grass and eucalyptus riparian buffers in a pasture catchment,Western Australia,part 2: water quality     

Lucy A. McKergow  Ian P. Prosser  David M. Weaver  Rodger B. Grayson  Adrian E. G. Reed 《水文研究》2006,20(11):2327-2346

Declining water quality on the south coast of Western Australia has been linked to current agricultural practices. Riparian buffers were identified as a tool available to farmers and catchment managers to achieve water quality improvements. This study compares 10 m wide regenerating grass and Eucalyptus globulus buffer performance. Surface and subsurface water quality were monitored over a 3‐year period. Nutrient and sediment transport were both dominated by subsurface flow, in particular through the B‐horizon, and this may seriously limit the surface‐runoff‐related functions of the riparian buffers. Riparian buffer trapping efficiencies were variable on an event basis and annual basis. The grass buffer reduced total phosphorus, filterable reactive phosphorus, total nitrogen and suspended sediment loads from surface runoff by 50 to 60%. The E. globulus buffer was not as effective, and total load reductions in surface runoff ranged between 10 and 40%. A key difference between the grass and E. globulus buffers was the seasonality of sediment and nutrient transport. Surface runoff, and therefore sediment and nutrient transport, occurred throughout the year in the E. globulus buffer, but only during the winter in the grass buffer. As a consequence of high summer nutrient and sediment concentrations, half the annual loads moving via surface runoff pathways through the E. globulus buffer were transported during intense summer storms. This study demonstrates that grass and E. globulus riparian buffers receiving runoff from pasture under natural rainfall can reduce sediment and nutrient loads from surface runoff. However, in this environment the B‐horizon subsurface flow is the dominant flowpath for nutrient transport through the riparian buffers, and this subsurface flow pathway carries contaminant loads at least three times greater than surface runoff. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献