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71.
G. W. Lester A. H. Clark T. K. Kyser H. R. Naslund 《Contributions to Mineralogy and Petrology》2013,166(1):329-349
Isobaric (200 MPa) experiments have been performed to investigate the effects of H2O alone or in combination with P, S, F or Cl on liquid-phase separation in melts in the systems Fe2SiO4–Fe3O4–KAlSi2O6–SiO2, Fe3O4–KAlSi2O6–SiO2 and Fe3O4–Fe2O3–KAlSi2O6–SiO2 with or without plagioclase (An50). Experiments were heated in a rapid-quench internally heated pressure vessel at 1,075, 1,150 or 1,200 °C for 2 h. Experimental fO2 was maintained at QFM, NNO or MH oxygen buffers. H2O alone or in combination with P, S or F increases the temperature and composition range of two-liquid fields at fO2 = NNO and MH buffers. P, S, F and Cl partition preferentially into the Fe-rich immiscible liquid. Two-liquid partition coefficients for Fe, Si, P and S correlate well with the degree of polymerization of the SiO2-rich liquid and plot on similar but distinct power-law curves compared with equivalent anhydrous or basaltic melts. The addition of 2 wt% S to the system Fe3O4–Fe2O3–KAlSi2O6–SiO2 stabilizes three immiscible melts with Fe-, FeS- and Si-rich compositions. H2O-induced suppression of liquidus temperatures in the experimental systems, considered with the effects of pressure on the temperature and composition ranges of two-liquid fields in silicate melts, suggests that liquid-phase separation may be stable in some H2O-rich silicate magmas at pressures in excess of 200 MPa. 相似文献
72.
S. Sembay G. Branduardi‐Raymont J.P. Eastwood D.G. Sibeck A. Abbey P. Brown J.A. Carter C.M. Carr C. Forsyth D. Kataria S. Kemble S. Milan C.J. Owen A.M. Read L. Peacocke C.S. Arridge A.J. Coates M.R. Collier S.W.H. Cowley A.N. Fazakerley G. Fraser G.H. Jones R. Lallement M. Lester F.S. Porter T. Yeoman 《Astronomische Nachrichten》2012,333(4):388-392
AXIOM (Advanced X‐ray Imaging Of the Magnetosphere) is a concept mission which aims to explain how the Earth's magnetosphere responds to the changing impact of the solar wind using a unique method never attempted before; performing wide‐field soft X‐ray imaging and spectroscopy of the magnetosheath, magnetopause and bow shock at high spatial and temporal resolution. Global imaging of these regions is possible because of the solar wind charge exchange (SWCX) process which produces elevated soft X‐ray emission from the interaction of high charge‐state solar wind ions with primarily neutral hydrogen in the Earth's exosphere and near‐interplanetary space (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
73.
Complex movement patterns by foraging loggerhead sea turtles outside the breeding season identified using Argos‐linked Fastloc‐Global Positioning System 下载免费PDF全文
Antoine M. Dujon Gail Schofield Rebecca E. Lester Kostas Papafitsoros Graeme C. Hays 《Marine Ecology》2018,39(1)
We used Argos‐linked Fastloc‐Global Positioning System (Argos‐linked Fastloc‐GPS) satellite tags to investigate how loggerhead sea turtles use neritic foraging habitats at multiple scales. Out of 24 turtles, six individuals used more than one foraging site, with all sites being separated by >25 km. These six individuals used up to four sites, remaining at each site for a mean of 150 days and returning to the same site a minimum of 52 days later. The other 18 turtles remained in a single site. The area within sites was not used uniformly, with 15 out of 24 turtles exhibiting complex movement patterns within and amongst up to five focal patches, which were typically 0.1–5.0 km apart within a single site. Movements between sites and patches might sometimes have reflected overwintering behaviour; however, similar movement patterns occurred at multiple times of the year, suggesting other factors were also involved. Use of multiple sites and patches might be driven by differences in resource availability, such as food and/or night‐time refuges, competition, or exploratory movement to investigate or locate alternative patches. We confirmed competition via direct visual observations of aggressive interactions between individuals at one foraging patch. Our results illustrate the importance of standardizing data to the same number of locations per day and night to accurately delineate key areas used by turtles or for evidence‐based marine protected area planning. 相似文献
74.
I. Kristen H. Wilkes A. Vieth K.-G. Zink B. Plessen J. Thorpe T. C. Partridge H. Oberhänsli 《Journal of Paleolimnology》2010,44(1):143-160
Comparing the organic matter (OM) composition of modern and past lake sediments contributes to the understanding of changes
in lacustrine environments over time. We investigate modern plant and lake-water samples as well as modern and ancient sediment
samples from the Tswaing Crater in South Africa using biomarker and stable carbon isotope analyses on bulk OM and specific
biomarker compounds. The characteristic molecular markers for higher land plants (predominantly C3-type deciduous angiosperms)
in Lake Tswaing are long-chain n-alkanes (n-C27−33), n-alkanols (n-C28+30), stigmasterol, β-sitosterol, β-amyrin, α-amyrin and lupeol. The C17
n-alkane, tetrahymanol, gammaceran-3-one and C29 sterols dominate the lipid fraction of autochthonously produced OM. By comparing stable carbon isotope analyses on bulk OM
and the characteristic biomarkers, we follow the modern carbon cycle in the crater environment and find indications for methanotrophic
activity in the lake from isotopically depleted moretene. A comparative study of core sediments reveals changes in the terrestrial
(C3 versus C4) and aquatic bioproductivity and allows insights into the variability of the carbon cycle under the influence
of changing climatic conditions for the time from the end of the last glacial (Termination I) to the late Holocene, ca. 14,000–2,000
calibrated years before present (years BP). The most pronounced changes occur in the aquatic realm after ca. 10,000 years
BP when our results imply climate swings from more humid to more arid and after 7,500 years BP to gradually more humid conditions
again, which can be related to a shift in the position of the Inter-Tropical Convergence Zone or to changes in the tropical
atmosphere–ocean interaction. Long-chain alkenones (LCAs) have been identified in ancient lake sediments from Africa for the
first time. They occur in samples older than 7,500 years BP and their distribution (dominance of C38 and of tri- over tetra-unsaturated LCAs) is distinctly different from other published records suggesting a to date unknown
source organism. 相似文献
75.
During summer of 2009, multi-channel marine seismic reflection data and wide-angle refraction data were acquired as part of the joint NSF and Taiwanese-funded TAIGER program with the goal of understanding the dynamics of arc-continent collision in Taiwan. One of the principle difficulties of crustal-scale imaging with marine reflection data such as these is the prevalent multiple contamination that obscures many of the deep crustal targets. Without effective treatment of multiples, many of the objectives of the TAIGER active source program may not be achieved. We present three profiles, one from each acquisition leg, that demonstrate the effectiveness of 2D surface-related multiple elimination (SRME) and radon filtering in attenuating much of this unwanted energy in broad ranges of water depths, seafloor topographies and lithologies. Two profiles from south of Taiwan image 3–4 km of sedimentary strata overlying moderately extended continental crust along the Eurasia continental shelf and a 5–6 km thick sedimentary section overlying thin crust consisting of faulted blocks and volcanic bodies along the continental slope. Our multiple attenuation efforts also reveal a seaward-dipping normal fault that penetrates into the upper mantle and separates thick crust of the continental shelf from thin crust of the continental slope. A profile from east of Taiwan reveals thin ocean crust of the Philippine Sea plate subducting beneath the Ryukyu trench that may be traced beneath the accretionary prism and Ryukyu forearc. These profiles demonstrate the success of our imaging strategy in the range of imaging environments spanned by the TAIGER marine reflection seismic data. 相似文献
76.
Abstract: This article tracks the passage of Aboriginal protection, as a contested imperial institution, from the Caribbean to Australia and Aotearoa New Zealand via the Cape Colony and Britain. In doing so, it reconfigures the historical geographies of colonial philanthropy, and of those individuals who sought to implement and resist it, as a set of specific, intersecting trajectories. These trajectories, of people, ideas and texts, both connected and remade multiple colonial places. The article also advocates positioning the contemporary politics of the colonial past in Britain, Australia and Aotearoa New Zealand, within a wider, trans‐imperial, set of connections. 相似文献
77.
Kristen Coppin Mark Halpern Douglas Scott Colin Borys James Dunlop Loretta Dunne Rob Ivison Jeff Wagg Itziar Aretxaga Elia Battistelli rew Benson rew Blain Scott Chapman Dave Clements Simon Dye Duncan Farrah David Hughes Tim Jenness Eelco van Kampen Cedric Lacey Angela Mortier Alexandra Pope Robert Priddey Stephen Serjeant Ian Smail Jason Stevens Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2008,384(4):1597-1610
A follow-up survey using the Submillimetre High-Angular Resolution Camera (SHARC-II) at 350 μm has been carried out to map the regions around several 850-μm-selected sources from the Submillimetre HAlf Degree Extragalactic Survey (SHADES). These observations probe the infrared (IR) luminosities and hence star formation rates in the largest existing, most robust sample of submillimetre galaxies (SMGs). We measure 350-μm flux densities for 24 850-μm sources, seven of which are detected at ≥2.5σ within a 10 arcsec search radius of the 850-μm positions. When results from the literature are included the total number of 350-μm flux density constraints of SHADES SMGs is 31, with 15 detections. We fit a modified blackbody to the far-IR (FIR) photometry of each SMG, and confirm that typical SMGs are dust-rich ( M dust ≃ 9 × 108 M⊙ ) , luminous ( L FIR ≃ 2 × 1012 L⊙ ) star-forming galaxies with intrinsic dust temperatures of ≃35 K and star formation rates of ≃400 M⊙ yr−1 . We have measured the temperature distribution of SMGs and find that the underlying distribution is slightly broader than implied by the error bars, and that most SMGs are at 28 K with a few hotter. We also place new constraints on the 350-μm source counts, N 350 (>25 mJy) ∼ 200–500 deg−2 . 相似文献
78.
79.
Weather observations on Whistler Mountain during five storms 总被引:1,自引:0,他引:1
Julie M. Thériault Kristen L. Rasmussen Teresa Fisico Ronald E. Stewart Paul Joe Ismail Gultepe Marilys Clément George A. Isaac 《Pure and Applied Geophysics》2014,171(1-2):129-155
A greater understanding of precipitation formation processes over complex terrain near the west coast of British Colombia will contribute to many relevant applications, such as climate studies, local hydrology, transportation, and winter sport competition. The phase of precipitation is difficult to determine because of the warm and moist weather conditions experienced during the wintertime in coastal mountain ranges. The goal of this study is to investigate the wide range of meteorological conditions that generated precipitation on Whistler Mountain from 4–12 March 2010 during the SNOW-V10 field campaign. During this time period, five different storms were documented in detail and were associated with noticeably different meteorological conditions in the vicinity of Whistler Mountain. New measurement techniques, along with the SNOW-V10 instrumentation, were used to obtain in situ observations during precipitation events along the Whistler mountainside. The results demonstrate a high variability of weather conditions ranging from the synoptic-scale to the macro-scale. These weather events were associated with a variation of precipitation along the mountainside, such as events associated with snow, snow pellets, and rain. Only two events associated with a rain–snow transition along the mountainside were observed, even though above-freezing temperatures along the mountainside were recorded 90 % of the time. On a smaller scale, these events were also associated with a high variability of snowflake types that were observed simultaneously near the top of Whistler Mountain. Overall, these detailed observations demonstrate the importance of understanding small-scale processes to improve observational techniques, short-term weather prediction, and longer-term climate projections over mountainous regions. 相似文献
80.
N.J.T. Edberg A.I. Eriksson U. Auster S. Barabash A. Bößwetter C.M. Carr S.W.H. Cowley E. Cupido M. Fränz K.-H. Glassmeier R. Goldstein M. Lester R. Lundin R. Modolo H. Nilsson I. Richter M. Samara J.G. Trotignon 《Planetary and Space Science》2009,57(8-9):1085-1096
We present the first two-spacecraft near-simultaneous observations of the Martian bow shock (BS), magnetic pileup boundary (MPB) and photo-electron boundary (PEB) obtained by the plasma instruments onboard Rosetta and Mars Express during the Rosetta Mars flyby on February 25, 2007. Our observations are compared with shape models for the BS and MPB derived from previous statistical studies. The MPB is found at its expected position but the BS for this event is found significantly closer to the planet than expected for the rather slow and moderately dense solar wind. Cross-calibration of the density measurements on the two spacecraft gives a density profile through the magnetosheath, indicating an increasing solar wind flux during the Rosetta passage which is consistent with the multiple BS crossings at the Rosetta exit. 相似文献