The SAURON project – IV. The mass-to-light ratio, the virial mass estimator and the Fundamental Plane of elliptical and lenticular galaxies     

Michele Cappellari  R. Bacon  M. Bureau  M. C. Damen  Roger L. Davies  P. T. de Zeeuw  Eric Emsellem  Jesús Falcón-Barroso  Davor Krajnovi&#;  Harald Kuntschner  Richard M. McDermid  Reynier F. Peletier  Marc Sarzi  Remco C. E. van den Bosch  Glenn van de Ven 《Monthly notices of the Royal Astronomical Society》2006,366(4):1126-1150

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Distribution and ecology of the crabs Cyclograpsus lavauxi and C. insularum in Northern New Zealand     

Marjorie R. Bacon 《新西兰海洋与淡水研究杂志》2013,47(3-4):415-426

The differences between the crabs Cyclograpsus lavauxi (Milne Edwards, 1853) and C. insularum (Campbell and Griffin, 1966) are outlined. Cyclograpsus lavauxi has long been known to be very common in New Zealand, but C insularum was considered very rare and had been collected only six times since 1929.

In 1970, 60 spot surveys in the northern part of the North Island of New Zealand revealed 14 new populations of Cyclograpsus insularum.

Both species are found under boulders high on the beach. Cyclograpsus lavauxi occurs at maximum density higher on the shore than the maximum numbers of C. insularum, but the zones overlap widely. Cyclograpsus insularum occurs on substrates of smaller sand and silt content than those on which C. lavauxi is found.  相似文献   

Morphology and kinematics of the ionised gas in early-type galaxies     

Jesús Falcn-Barroso  Marc Sarzi  Roland Bacon  Martin Bureau  Michele Cappellari  Roger L. Davies  Eric Emsellem  Kambiz Fathi  Davor Krajnovi&#x;  Harald Kuntschner  Richard M. McDermid  Reynier F. Peletier  Tim de Zeeuw 《New Astronomy Reviews》2006,49(10-12):515

We present results of our ongoing study of the morphology and kinematics of the ionised gas in 48 representative nearby elliptical and lenticular galaxies using the SAURON integral-field spectrograph on the 4.2m William Herschel Telescope. Making use of a recently developed technique, emission is detected in 75% of the galaxies. The ionised-gas distributions display varied morphologies, ranging from regular gas disks to filamentary structures. Additionally, the emission-line kinematic maps show, in general, regular motions with smooth variations in kinematic position angle. In most of the galaxies, the ionised-gas kinematics is decoupled from the stellar counterpart, but only some of them present signatures of recent accretion of gaseous material. The presence of dust is very common in our sample and is usually accompanied by gas emission. Our analysis of the [Oiii]/Hβ emission-line ratios, both across the whole sample as well as within the individual galaxies, suggests that there is no unique mechanism triggering the ionisation of the gas.  相似文献   

Stable isotope and petrologic evidence for open-system degassing during the climactic and pre-climactic eruptions of Mt. Mazama, Crater Lake, Oregon     

Charles W. Mandeville  James D. Webster  Bruce E. Taylor  Akira Sasaki  Charles R. Bacon 《Geochimica et cosmochimica acta》2009,73(10):2978-3012

Evaluation of the extent of volatile element recycling in convergent margin volcanism requires delineating likely source(s) of magmatic volatiles through stable isotopic characterization of sulfur, hydrogen and oxygen in erupted tephra with appropriate assessment of modification by degassing. The climactic eruption of Mt. Mazama ejected approximately 50 km³ of rhyodacitic magma into the atmosphere and resulted in formation of a 10-km diameter caldera now occupied by Crater Lake, Oregon (lat. 43°N, long. 122°W). Isotopic compositions of whole-rocks, matrix glasses and minerals from Mt. Mazama climactic, pre-climactic and postcaldera tephra were determined to identify the likely source(s) of H₂O and S. Integration of stable isotopic data with petrologic data from melt inclusions has allowed for estimation of pre-eruptive dissolved volatile concentrations and placed constraints on the extent, conditions and style of degassing.Sulfur isotope analyses of climactic rhyodacitic whole rocks yield δ³⁴S values of 2.8-14.8‰ with corresponding matrix glass values of 2.4-13.2‰. δ³⁴S tends to increase with stratigraphic height through climactic eruptive units, consistent with open-system degassing. Dissolved sulfur concentrations in melt inclusions (MIs) from pre-climactic and climactic rhyodacitic pumices varies from 80 to 330 ppm, with highest concentrations in inclusions with 4.8-5.2 wt% H₂O (by FTIR). Up to 50% of the initial S may have been lost through pre-eruptive degassing at depths of 4-5 km. Ion microprobe analyses of pyrrhotite in climactic rhyodacitic tephra and andesitic scoria indicate a range in δ³⁴S from −0.4‰ to 5.8‰ and from −0.1‰ to 3.5‰, respectively. Initial δ³⁴S values of rhyodacitic and andesitic magmas were likely near the mantle value of 0‰. Hydrogen isotope (δD) and total H₂O analyses of rhyodacitic obsidian (and vitrophyre) from the climactic fall deposit yielded values οf −103 to −53‰ and 0.23-1.74 wt%, respectively. Values of δD and wt% H₂O of obsidian decrease towards the top of the fall deposit. Samples with depleted δD, and mantle δ¹⁸O values, have elevated δ³⁴S values consistent with open-system degassing. These results imply that more mantle-derived sulfur is degassed to the Earth’s atmosphere/hydrosphere through convergent margin volcanism than previously attributed. Magmatic degassing can modify initial isotopic compositions of sulfur by >14‰ (to δ³⁴S values of 14‰ or more here) and hydrogen isotopic compositions by 90‰ (to δD values of −127‰ in this case).  相似文献   

The SAURON project – XIII. SAURON–GALEX study of early-type galaxies: the ultraviolet colour–magnitude relations and Fundamental Planes     

Hyunjin Jeong  Sukyoung K. Yi  Martin Bureau  Roger L. Davies  Jesús Falcón-Barroso  Glenn van de Ven †  Reynier F. Peletier  Roland Bacon  Michele Cappellari  Tim de Zeeuw  Eric Emsellem  Davor Krajnovi&#;  Harald Kuntschner  Richard M. McDermid  Marc Sarzi  Remco C. E. van den Bosch 《Monthly notices of the Royal Astronomical Society》2009,398(4):2028-2048

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Reinterpretation of an archaeological pebble culture from the Middle Mekong River valley,Cambodia     

Fabrice Demeter  Elise Patole‐Edoumba  Philippe Duringer  Anne‐Marie Bacon  Pheng Sytha  Maxim Bano  Vin Laychour  Mao Cheangleng  Vn Sari 《Geoarchaeology》2010,25(1):75-95

In 1963, E. Saurin and J.‐P. Carbonnel discovered the Sre Sbov site on an alluvial terrace of the Mekong River in central Cambodia. Saurin described a lithic typology dating to the Lower/Middle Pleistocene from this site. Although the original lithic assemblage has been lost, this typology has been used continuously as a reference by Southeast Asian prehistorians. In 2007, a Khmer–French team conducted excavations at Sre Sbov that yielded numerous pebbles and cobbles showing apparently convincing handmade removals, as Saurin had previously described. However, an in‐depth study of this assemblage, combined with a geological survey of the area, led to the conclusion that the stones were, in fact, of natural origin, and that for this reason their typology should be disregarded. Using satellite imagery and geological surveys, we explain how such a misinterpretation may have occurred and define a “buffer zone,” corresponding to the maximal extent of the proto‐Mekong River, where fluvially reworked pebbles and cobbles resembling artifacts may be recovered. © 2009 Wiley Periodicals, Inc.  相似文献   

Heavy metals deposited from the atmosphere on upland Scottish soils: Chemical and lead isotope studies of the association of metals with soil components   总被引：2，自引：0，他引：2  

Jeffrey R. Bacon  Irene J. Hewitt 《Geochimica et cosmochimica acta》2005,69(1):19-33

Three soil profiles taken from the Hartwood Research Station in Central Scotland have been analyzed using chemical digestion and extraction techniques to investigate the chemical association of heavy metals deposited from the atmosphere. Total digestion, EDTA extraction and the BCR (Bureau Communitaire de Reference) sequential extraction procedure were used. In addition, lead isotope ratios in the whole soils and in the fractions from the sequential extraction procedure were measured using thermal ionisation mass spectrometry. All the digestion and extraction procedures gave clear indication of enhanced concentrations of heavy metals in surface soils, in particular for lead and zinc. Whereas total digestion gave a good indication of the heavy metal status of the soils, the extraction procedures were necessary to provide information on chemical association of the metals with soil components, information needed to understand the soil processes involved in mobilization of metals. Lead isotope analysis of the whole soils revealed a consistent picture of lower ²⁰⁶Pb/²⁰⁷Pb ratios in surface soils (1.140-1.147) than in soils at 20-30 cm depth (1.182-1.190). The steady progression from the lower to higher ratios down the profile was clear indication that anthropogenic lead had penetrated to some degree into the deeper soils. The combination of sequential extraction and lead isotope analysis proved to be a powerful approach to studying this effect in more detail and showed that the fractions extractable from 20 to 30 cm soils contained lead with much lower ²⁰⁶Pb/²⁰⁷Pb ratios (1.174-1.178) than the residual fraction (1.196-1.200). As the extractable fractions contained ≥85% of the lead in the soil, a substantial portion of lead at 20-30 cm depth was of anthropogenic origin. The ²⁰⁶Pb/²⁰⁷Pb ratios of 1.174-1.178 found in the extractable fractions suggested that the mobile component of the anthropogenic lead was that deposited before the introduction of leaded petrol.  相似文献   

Ion microprobe measurement of strontium isotopes in calcium carbonate with application to salmon otoliths     

Peter K. Weber  Charles R. Bacon  B. Lynn Ingram 《Geochimica et cosmochimica acta》2005,69(5):1225-1239

The ion microprobe has the capability to generate high resolution, high precision isotopic measurements, but analysis of the isotopic composition of strontium, as measured by the ⁸⁷Sr/⁸⁶Sr ratio, has been hindered by isobaric interferences. Here we report the first high precision measurements of ⁸⁷Sr/⁸⁶Sr by ion microprobe in calcium carbonate samples with moderate Sr concentrations. We use the high mass resolving power (7000 to 9000 M.R.P.) of the SHRIMP-RG ion microprobe in combination with its high transmission to reduce the number of interfering species while maintaining sufficiently high count rates for precise isotopic measurements. The isobaric interferences are characterized by peak modeling and repeated analyses of standards. We demonstrate that by sample-standard bracketing, ⁸⁷Sr/⁸⁶Sr ratios can be measured in inorganic and biogenic carbonates with Sr concentrations between 400 and 1500 ppm with ∼2‰ external precision (2σ) for a single analysis, and subpermil external precision with repeated analyses. Explicit correction for isobaric interferences (peak-stripping) is found to be less accurate and precise than sample-standard bracketing. Spatial resolution is ∼25 μm laterally and 2 μm deep for a single analysis, consuming on the order of 2 ng of material. The method is tested on otoliths from salmon to demonstrate its accuracy and utility. In these growth-banded aragonitic structures, one-week temporal resolution can be achieved. The analytical method should be applicable to other calcium carbonate samples with similar Sr concentrations.  相似文献   

Targeted GOES Satellite Observations to Improve Hurricane Track Forecast: A Case Study of Hurricane Floyd     

Zafer Boybeyi  Elena Novakovskaia  Rosalyn MacCracken  David P. Bacon  Michael L. Kaplan 《Pure and Applied Geophysics》2007,164(10):2083-2100

This study performs a set of Observing System Simulation Experiments (OSSEs) using Geostationary Operational Environmental Satellite (GOES) soundings. The primary objective of the OSSEs is to demonstrate that targeted observations can improve forecast accuracy by enhancing the initial conditions and mitigating their uncertainties. Hurricane Floyd (1999) is chosen as a study case. The main reason for choosing hurricane Floyd as a test case is that the movement of the storm was dictated by a mid-level complex polar jet steering flow region. This well-defined feature allowed us to examine the inaccuracy of analysis over the steering flow area using GOES soundings as targeted observations and its impact on the forecast track error. The set of experiments starts from a baseline forecast of hurricane Floyd using the Operational Multiscale Environment model with Grid Adaptivity (OMEGA). From GOES satellite soundings, atmospheric vertical profiles were extracted to simulate targeted observations. These data extracts were assimilated in the initial conditions to simulate new forecasts of hurricane Floyd which were then compared against both the baseline track and observed track. It was found that targeted observations in a forecast sensitive area can help to reduce hurricane forecast track error. Assimilation of only the subset of data (about 50 soundings) from the subjectively chosen fully sampled target region produced a considerable reduction of the track forecast errors (about 30%) within the first critical three days of the forecast.  相似文献   

Recent seismicity of southeastern Ghana     

M. Bacon  J.K.A. Banson 《Earth and Planetary Science Letters》1979,44(1):43-46

Recent studies of DSDP samples from layer 2A of oceanic basement have found complex magnetic stratigraphies that seem incompatible with the frequent existence of linear short-wavelength anomalies caused by palaeomagnetic field behavior. Statistical models are developed for the lateral variation of the average magnetization of layer 2A: a Poisson series for reversals of the earth's field and a stairstep random series for discrete magnetic units. It is shown with the power-density spectra of these statistical models that lateral inhomogeneities must average out over distances of less than a few hundred meters. Specifically, individual magnetic units of the type seen at DSDP Site 332 cannot extend uniformly for distances greater than a few hundred meters.  相似文献