Crystallization of tholeiitic basalt in Alae Lava Lake,Hawaii     

D. L. Peck  T. L. Wright  J. G. Moore 《Bulletin of Volcanology》1966,29(1):629-655

The eruption of Kilauea Volcano August 21–23, 1963, left 600,000 cubic meters of basaltic lava in a lava lake as much as 15 meters deep in Alae pit crater. Field studies of the lake began August 27 and include repeated core drilling, measurements of temperature in the crust and melt, and precise level surveys of the lake surface. The last interstitial melt in the lake solidified late in September 1964; by mid August 1965 the maximum temperature was 690°C at a depth of 11.5 meters. Pumice air-quenched from about 1140°C contains only 5 percent crystals — clinopyroxene, cuhedral olivine (Fo ₈₀), and a trace of plagioclase, (An ₇₀). Drill cores taken from the zone of crystallization in the lake show that olivine continued crystallizing to about 1070°C; below that it reacts with the melt, becoming corroded and mantled by pyroxene and plagioclase. Below 1070°C, pyroxene and plagioclase crystallized at a constant ratio. Ilmenite first appeared at about 1070°C and was joined by magnetite at about 1050°C; both increased rapidly in abundance to 1000°C. Apatite first appeared as minute needles in interstitial glass at 1000°C. Both the abundance and index of refraction of glass quenched from melt decreased nearly linearly with falling temperature. At 1070°C the quenched lava contains about 65 percent dark-brown glass with an index of 1.61; at 980°C it contains about 8 percent colorless glass with an index of 1.49. Below 980°C, the percentage of glass remained constant. Progressive crystallization forced exsolution of gases from the melt fraction; these formed vesicles and angular pores, causing expansion of the crystallizing lava and lifting the surface of the central part of the lake an average of 19.5 cm. The solidified basalt underwent pneumatolitic alteration, including deposition of cristobalite at 800°C, reddish alteration of olivine at 700°C, tarnishing of ilmenite at 550°C, deposition of anhydrite at 250°C, and deposition of native sulfur at 100°C. Ferric-ferrous ratios suggest that oxidation with maximum intensity between 550°C and 610°C moved downward in the crust as it cooled; this was followed by reduction at a temperature of about 100°C. The crystallized basalt is a homogeneous fine-grained rock containing on the average 48.3 percent by volume intergranular pyroxene (augite > pigeonite), 34.2 percent plagioclase laths (An_{60 70}), 7.9 percent interstitial glass, 6.9 percent opaques (ilmenite > magnetite), 2.7 percent olivine (Fo_{70 80}), and a trace of apatite. Chemical analyses of 18 samples, ranging from initially quenched pumice to lava cored more than a year after the eruption from the center and from near the base of the lake, show little variation from silica-saturated tholeiitic basalt containing 50.4 percent SiO₂, 2.4 percent Na₂O, and 0.54 percent K₂O. Apparently there was no significant crystal settling and no appreciable vapor-phase transport of these components during the year of crystallization. However, seven samples of interstitial liquid that had been filter-pressed into gash fractures and drill holes from partly crystalline mush near the base of the crust show large differences from the bulk composition of the solidified crust—lower MgO, CaO, and Al₂O₃; and higher total iron, TiO₂, Na₂O, K₂O, P₂O₅, and F, and, in most samples, SiO₂. The minor elements Ba, Ga, Li, Y, and Yb and possibly Cu tend to be enriched in the filter-pressed liquids, and Cr and possibly Ni tend to be depleted.  相似文献   

The University of Durham Mark 6 Gamma Ray Telescope     

P. Armstrong  P. M. Chadwick  P. J. Cottle  J. E. Dickinson  M. R. Dickinson  N. A. Dipper  S. E. Hilton  W. Hogg  J. Holder  T. R. Kendall  T. J. L. McComb  C. M. Moore  K. J. Orford  S. M. Rayner  I. D. Roberts  M. D. Roberts  M. Robertshaw  S. E. Shaw  K. Tindale  S. P. Tummey  K. E. Turver 《Experimental Astronomy》1999,9(2):51-80

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The search for our beginning: Roben Hutchison, 1983. Oxford University Press, 164 pp., U.S. $16.95     

Carleton B. Moore 《Geochimica et cosmochimica acta》1985,49(2):616

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Thorium adsorption in the ocean: reversibility and distribution amongst particle sizes     

Robert M Moore  Keith A Hunter 《Geochimica et cosmochimica acta》1985,49(11):2253-2257

Experiments have been carried out to determine whether the adsorption of Th by marine suspended particles is a reversible process. The results indicate reversibility on a time scale of hours. The distribution of Th between the ‘dissolved’ state (<0.22 μm particle size) and various particle size fractions has been compared with predictions based on a hyperbolic size distribution of marine particles assuming spherical geometry and surface adsorption. Thorium is present in small particles to a much smaller degree than such a model would predict, so that the use of 1 μm pore size filters to separate ‘dissolved’ and ‘particulate’ Th does not introduce serious errors. The implications of these results on the reversible exchange model of Bacon and Anderson (1982) and on the settling model of Tsunogai and Minagawa (1978) are discussed.  相似文献   

ERTS Imagery for Ground-Water Investigations     

Gerald K. Moore  Morris Deutsch 《Ground water》1975,13(2):214-226

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High pressure crystallization of the Ewarara,Kalka and Gosse Pile intrusions,Giles Complex,central Australia     

A. D. T. Goode  A. C. Moore 《Contributions to Mineralogy and Petrology》1975,51(2):77-97

Evidence is presented for the primary high pressure crystallization of the Ewarara, Kalka and Gosse Pile layered intrusions which form part of the Giles Complex in central Australia. These pressures are estimated at 10 to 12 kb. The high pressure characteristics include subsolidus reactions between olivine and plagioclase, orthopyroxene and plagioclase, and orthopyroxene and spinel; spinel and rutile exsolution in both ortho- and clino-pyroxene; spinel exsolution in plagioclase; high Al₂O₃ and Cr₂O₃ contents of both ortho- and clinopyroxene; high Al^VI in clinopyroxene; dominance of orthopyroxene as an early crystallizing phase; high distribution coefficients for co-existing pyroxene pairs; and thin chilled margins. Such phenomena are rare in documented layered basic intrusions.  相似文献   

A mechanical interpretation of the vein and dyke systems of the S. W. England orefield     

J. McMahon Moore 《Mineralium Deposita》1975,10(4):374-388

Geological plans and sections showing the traces of veins, faults and porphyry dykes associated with the Hercynian batholith, have been used to construct diagrams representing the trajectories of the minimum and intermediate principal stress axes as they were at the time of intrusion of the dykes and as the veinlode fissures formed. The dykes and veins were emplaced during a complicated series of events and the trajectory diagrams represent stress conditions during these overlapping periods of time towards the end of intrusion of the batholith. The mineralizing fluids emanated from the cores of plutons by means of pregranite faults, primary igneous joints, and structures created by intrusion, including faults and extension fissures. The trajectory diagrams indicate that the mapped configuration of veins and porphyry dykes results from fluid pressures, exerted by the mobile cores of granitic cupolas situated within a regional stress field. The stress models also indicate that fugitive dyke magma or hydrothermal fluids, emanating from a cupola, will make the mechanically easiest exit through the flanks of the intrusion. This explains the asymmetrical disposition of belts of mineralization which border the granite cupolas of southwest England.  相似文献   

Lithium,sodium and potassium abundances in carbonaceous chondrites     

Walter Nichiporuk  Carleton B Moore 《Geochimica et cosmochimica acta》1974,38(11):1691-1701

Concentrations of lithium, sodium, and potassium in 18 carbonaceous chondrites were determined in the same sample solution by atomic absorption. Mean abundances in carbonaceous Type I chondrites are, in atoms 10⁶ Si: Li = 60.1, Na = 5800, K = 3700. Relative to Type I carbonaceous chondrites, abundances in Type II's are: Li = 0.87, Na = 0.61, K = 0.58; and in Type III's Li = 0.82, Na = 0.49, K = 0.36. Evidently there is a differential depletion of potassium relative to sodium in Type III's, suggesting a fractionation after accretion.  相似文献   

A spectral optimally interpolated mean sea surface from satellite radar altimetry     

R. A. Cullen  P. Moore 《Journal of Geodesy》2001,75(4):188-198

 A technique is presented for the development of a high-precision and high-resolution mean sea surface model utilising radar altimetric sea surface heights extracted from the geodetic phase of the European Space Agency (ESA) ERS-1 mission. The methodology uses a cubic-spline fit of dual ERS-1 and TOPEX crossovers for the minimisation of radial orbit error. Fourier domain processing techniques are used for spectral optimal interpolation of the mean sea surface in order to reduce residual errors within the initial model. The EGM96 gravity field and sea surface topography models are used as reference fields as part of the determination of spectral components required for the optimal interpolation algorithm. A comparison between the final model and 10 cycles of TOPEX sea surface heights shows differences of between 12.3 and 13.8 cm root mean square (RMS). An un-optimally interpolated surface comparison with TOPEX data gave differences of between 15.7 and 16.2 cm RMS. The methodology results in an approximately 10-cm improvement in accuracy. Further improvement will be attained with the inclusion of stacked altimetry from both current and future missions. Received: 22 December 1999 / Accepted: 6 November 2000  相似文献   

Subsidence of Surtsey volcano, 1967–1991     

James G Moore  Sveinn Jakobsson  Josef Holmjarn 《Bulletin of Volcanology》1992,55(1-2):17-24

The Surtsey marine volcano was built on the southern insular shelf of Iceland, along the seaward extension of the east volcanic zone, during episodic explosive and effusive activity from 1963 to 1967. A 1600-m-long, east-west line of 42 bench marks was established across the island shortly after volcanic activity stopped. From 1967 to 1991 a series of leveling surveys measured the relative elevation of the original bench marks, as well as additional bench marks installed in 1979, 1982 and 1985. Concurrent measurements were made of water levels in a pit dug on the north coast, in a drill hole, and along the coastline exposed to the open ocean. These surveys indicate that the dominant vertical movement of Surtsey is a general subsidence of about 1.1±0.3 m during the 24-year period of observations. The rate of subsidence decreased from 15–20 cm/year for 1967–1968 to 1–2 cm/year in 1991. Greatest subsidence is centered about the eastern vent area. Through 1970, subsidence was locally greatest where the lava plain is thinnest, adjacent to the flanks of the eastern tephra cone. From 1982 onward, the region closest to the hydrothermal zone, which is best developed in the vicinity of the eastern vent, began showing less subsidence relative to the rest of the surveyed bench marks. The general subsidence of the island probably results from compaction of the volcanic material comprising Surtsey, compaction of the sea-floor sediments underlying the island, and possibly downwarping of the lithosphere due to the laod of Surtsey. The more localized early downwarping near the eastern tephra cone is apparently due to greater compaction of tephra relative to lava. The later diminished local subsidence near the hydrothermal zone is probably due to a minor volume increase caused by hydrous alteration of glassy tephra. However, this volume increase is concentrated at depth beneath the bottom of the 176-m-deep cased drillhole.  相似文献