The Hinode Spectro-Polarimeter     

B. W. Lites  D. L. Akin  G. Card  T. Cruz  D. W. Duncan  C. G. Edwards  D. F. Elmore  C. Hoffmann  Y. Katsukawa  N. Katz  M. Kubo  K. Ichimoto  T. Shimizu  R. A. Shine  K. V. Streander  A. Suematsu  T. D. Tarbell  A. M. Title  S. Tsuneta 《Solar physics》2013,283(2):579-599

The joint Japan/US/UK Hinode mission includes the first large-aperture visible-light solar telescope flown in space. One component of the Focal Plane Package of that telescope is a precision spectro-polarimeter designed to measure full Stokes spectra with the intent of using those spectra to infer the magnetic-field vector at high precision in the solar photosphere. This article describes the characteristics of the flight hardware of the Hinode Spectro-Polarimeter, and summarizes its in-flight performance.  相似文献   

Tectonic implications of the immobile trace‐element geochemistry of mafic rocks bounding the Wonaminta Block     

A. C. Edwards 《Australian Journal of Earth Sciences》2013,60(7-8):459-465

The Wonaminta Block is bounded on its eastern and western margins by Lower Cambrian or upper Vendian intrusive and extrusive igneous rocks. The extrusive rocks include pillow lavas. Low‐grade metamorphism has not influenced the distribution of P2O3, Zr, Y, and Nb, but remobilization of Ti has occurred in rocks containing Ti within the oxide phases rather than in the silicate phases. Immobile trace‐element discrimination techniques indicate that the basalts on the western margin of the Wonaminta Block are alkaline whereas those on the eastern margin are tholeiitic. The possibility that these rocks represent petrological variants across an arc system is discussed.  相似文献   

Diatoms and ostracods as mid-Holocene palaeoenvironmental indicators,North Stromatolite Lake,Coorong National Park,South Australia ∗     

S. Edwards  Y. Bone  P. A. Gell  V. A. Gostin 《Australian Journal of Earth Sciences》2013,60(4):651-663

The Holocene carbonate sequence of perennial North Stromatolite Lake, located adjacent to the Coorong Lagoon near Salt Creek, South Australia, includes a prominent sapropelic unit (7 – 12% total organic carbon), in places more than 2 m thick, that was sampled for the purpose of radiocarbon dating and documenting its diatom and ostracod biostratigraphy. The recovered ostracods were also subjected to carbon and oxygen isotopic analysis. The bulk organic matter at the base of the sapropel yielded an uncalibrated ¹⁴C age of 6080 ± 60 y BP. Diatoms, where preserved, are almost exclusively benthic. Stratigraphic variation of the proportions of key indicator species in diatom assemblages records a marked oscillation between oligosaline and eusaline conditions in the hypolimnion during deposition of the sapropel. Ostracod carbon isotope data indicate that the lake at this time was eutrophic, thereby enriching the dissolved inorganic carbon of the hypolimnion in ¹³C. However, the observed secular variation in δ¹³C implies a mid-sapropel drop in productivity, caused by a freshening of the lake. Ostracod δ¹⁸O values display an overall increase through the sapropel consistent with the rising salinity of the hypolimnion. The existence of a flourishing benthic ostracod community, together with the valve ornamentation of Osticythere baragwanathi, indicates that the bottom waters were well oxygenated. Thus, anoxia was not a prerequisite for sapropel accumulation. The biostratigraphy and chemostratigraphy of the sapropel concur in suggesting a lack of climatic uniformity during its deposition, a period of ～1200 years. This study therefore highlights the potential of diatoms and ostracods in shallow perennial alkaline lakes along the Coorong coastal plain as proxies for short-term (10² – 10³ years) Holocene palaeoenvironmental change in southeastern Australia.  相似文献   

Metamorphism and Metasomatism at King Island Scheelite Mine     

A. B. Edwards  G. Baker  K. J. Callow 《Australian Journal of Earth Sciences》2013,60(3):55-98

Abstract

The King Island Scheelite Mine lies in the contact aureole of a granodiorite stock. Its open cut and numerous drill cores expose a contact metamorphosed and metasomatized series of finely interbedded argillaceous and calcareous sediments, with interleaved flows of picrite-basalt and basic pyroclastics, the scheelite ore being limited to two limestone horizons. The range and gradation in composition of the original rocks has resulted in an unusual variety of meta-morphic rocks, including forsterite-phlogopite-spinel-tremolite hornfels, anthophyllite-cordierite hornfels, biotite hornfels, actinolite hornfels, a variety of calc-flinta, and marbles. The original sedimentation gave rise to a rapid alternation of limestone and shale, many times repeated, and during metamorphism these rocks reacted with each other to produce narrow bands of calc-flinta.

Subsequent pyrometasomatism selectively converted the greater part of the marble beds to scheelite-bearing andradite skarn, leaving the various hornfels and calc-flinta very little affected. The replacement of the marble was a volume for volume process, and the conversion of 1,000,000 tons of marble to average grade ore involved the introduction of about 350,000 tons of SiO₂, 250,000 tons of Fe₂O₃, 55,000 tons AI₂O₃, 30,000 tons of H₂O and 82,500 tons of CaO.

The temperature of the contact metamorphism attained over 500° C, and the rocks cooled to about 400° C. before the pyrometasomatism occurred. The rocks giving rise to the various hornfels underwent varying degrees of contraction during metamorphism, whereas the limestones probably expanded during metamorphism, and became more permeable to solutions.  相似文献   

The GEOIDE Network –Integrating Research and Development for the Benefit of the Canadian Geomatics Industry     

Geoffrey Edwards  & Tom DeGroeve 《Transactions in GIS》2000,4(2):91-97

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The detection of lateral anisotropy of the ocean floor by electromagnetic methods   总被引：2，自引：0，他引：2  

Liming Yu  R. N. Edwards 《Geophysical Journal International》1992,108(2):433-441

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Results of a sea-floor electromagnetic survey over a sedimented hydrothermal area on the Juan de Fuca Ridge     

D. C. Nobes  L. K. Law  R. N. Edwards 《Geophysical Journal International》1992,110(2):333-346

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Cultured red alga to measure pollution     

Peter Edwards 《Marine pollution bulletin》1972,3(12):184-188

The red alga Callithamnion grew equally well in seawater samples from unpolluted and polluted localities. The species was insensitive to nitrate and phosphate levels of the medium and thus cannot be used as an indicator of eutrophication. Relatively small copper concentrations depressed the growth of the species. No difference in copper tolerance was demonstrated between isolates from unpolluted north-east Scotland and polluted County Durham, but the isolate from unpolluted south-west England was apparently less resistant to copper.  相似文献   

The ICE-MOSES experiment: Mapping permafrost zones electrically beneath the Beaufort Sea     

R. N. Edwards  P. A. Wolfgram  A. S. Judge 《Marine Geophysical Researches》1988,9(3):265-290

A novel variation of the geophysical technique known as MOSES, for Magnetometric Off-Shore Electrical Sounding, has been developed to map the electrical properties of the sea floor in Aretic regions. The particular target is the permafrost layer under the Beaufort Sea, a layer containing frozen or partially frozen sediment from 100 to 600 m thick underlying shallow sea water, typically 10 to 100 m deep, and several tens of metres of soft sediment. A detailed knowledge of the location and physical properties of the permafrost layer is essential for accurate interpretation of reflection seismic data. The permafrost can contain pockets, regions or layers of gas hydrate. The latter is both a possible resource and a hazard to drilling operations or hydrocarbon production. A local map of the permafrost zone is essential geotechnical information required prior to the construction of an offshore structure or pipeline.The MOSES method is particularly suitable for offshore electrical mapping as it can be made relatively insensitive to the shielding effects of the highly conductive sea water, in sharp contrast to many other electrical techniques. The transmitter is a vertical, long-wire bipole, extending from the sea surface to the sea floor. A commutated current is fed to two large electrodes: one near the sea surface and the other on the sea floor. The return current is through the sea water and the subjacent sediment. The receiver consists of two horizontal orthogonal coils located on the sea floor, and the data are measurements of two components of the magnetic field as a function of frequency and transmitter-receiver horizontal separation.The electrical conductivity of a sample of frozen material is much smaller than that of unfrozen or partially frozen sediment of the same type. Frozen and unfrozen thin layers are often observed sequentially throughout the geological section. The resistivity measured as a function of depth by an electrical logging tool is consequently highly variable. The resulting depth-averaged resistivity, the resistivity resolved by a surface electrical method, is macro-an-isotropic. An experimental design study reveals that both the vertical and horizontal averaged resistivities could be determined in a MOSES sounding without vertical scale distortion.A test of the methodology in very shallow water was conducted in the spring of 1986 at a site, approximate coordinates (70° N, 134.5° W), 85 km north-west of the town of Tuktoyaktuk. The instrumentation was lowered and subsequently recovered through holes in the ice which covers the Beaufort Sea at that time of the year. The transmitter power was obtained from a single lead-acid battery. Transmitter-receiver separations ranged from 10 to 300 m. A rapid increase in sediment resistivity with depth was observed. The higher resistivity values are consistent with those expected for a partially frozen zone.  相似文献   

Long-term and regional variability of phytoplankton biomass in the Northeast Atlantic (1960-1995)   总被引：2，自引：0，他引：2  

Edwards  Martin; Reid  Philip; Planque  Benjamin 《ICES Journal of Marine Science》2001,58(1):39-49

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