Geochemistry of Germanium,benchmark papers in Geology: edited by Jon N. Weber. series editor Rhodes W. Fairbeidge. Dowden,Hutchinson & Ross,Inc., 466 pp., 1973. $23.00     

Tony A Finkerty  John T Wasson 《Geochimica et cosmochimica acta》1975,39(5):774-775

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Volatiles from Hawaiian submarine basalts determined by dynamic high temperature mass spectrometry     

John S. Killingley  David W. Muenow 《Geochimica et cosmochimica acta》1975,39(11):1467-1473

Quantitative measurements of volatiles from Hawaiian submarine basalts have been made using a Knudsen cell dynamic-mass spectrometer system. The principal advantage of the technique is the ability to determine simultaneously the absolute amounts of more than one volatile released from the same sample.From mass pyrograms it was observed that the release of water was bimodal, with the major release occurring above 600°C. Water released below this temperature is believed not to have been present in the magma at the time of extrusion. Sulfur dioxide was evolved only after the bulk of the water was released and coincided with the general expansion and melting of the sample. Sulfur and carbon- containing gases which were released in surges (above 1000°C) correspond to the bursting of bubbles from the softened basalt.The molar amounts of vesicle gases were plotted as a function of extrusion depth. A change in the slope of the resulting linear curve indicates saturation of the basalt with respect to water.  相似文献   

Sr isotopes and the structural state of feldspars as indicators of post-magmatic hydrothermal activity in continental dolerites     

P. J. Patchett  O. van Breemen  R. F. Martin 《Contributions to Mineralogy and Petrology》1979,69(1):65-73

Late-crystallised interstitial alkali feldspars and a single epidote from selected Proterozoic dolerites in Sweden have higher initital ⁸⁷Sr/⁸⁶Sr ratios, (e.g., 0.709) than the early-crystallised minerals of the same rocks ( 0.704); anomalies in Rb and Sr concentrations are also noted. This radiogenically-enriched Sr must originate in the older host rocks of the intrusions. As the contaminated phases often occupy <1 % of the dolerite, only an aqueous fluid would have been capable of transporting the contamination through the 99% solid intrusions. Textural association of late feldspars with hydrous alteration products supports this interpretation. Feldspar structural data suggest that most dolerites have been affected by subsolidus aqueous fluids, causing extensive structural re-equilibration in interstitial K-feldspars, as well as occasional metasomatic effects. Anomalies in ⁸⁷Sr developed only where the fluids interacted with host rocks.  相似文献   

Estimating the surface wind speed over drifting pack ice from surface weather charts     

Uri Feldman  Philip J. Howarth  John A. Davies 《Boundary-Layer Meteorology》1979,16(4):421-429

Routine surface wind speed data, vital for the study of drifting pack ice, are not available for the polar oceans. Over sea, it has been demonstrated by Hasse that estimates of surface wind speed may be obtained from the geostrophic wind speed using linear formulae. Comparing estimated with observed data for six sites in Canada, it is found that the formulae may also be applied to obtain estimates of surface wind speed over pack ice.  相似文献   

REPLY TO the preceding Discussion by Moid U. Ahmad of "Fossil Ground-Water Gradients in Arid Regional Sedimentary Basins"     

John W. Lloyd 《Ground water》1979,17(2):218-218

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Chemical Changes in an Industrial Waste Liquid During Post-Injection Movement in a Limestone Aquifer, Pensacola, Florida     

G. G. Ehrlich  E. M. Godsy  C. A. Pascale  John Vecchioli 《Ground water》1979,17(6):562-573

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Long base line tilt and strain measurement     

Paul Davis  Keith Evans  John Hosfall  Geoffrey King 《Tectonophysics》1979,52(1-4)

Two types of noise afflict strain and tilt measurement. They may be categorized as “active” noise, which is due to atmospheric pressure variations, temperature variations, water-table variations and so forth; and “passive” or signal-generated noise which is a consequence of the interaction of the strain field of interest with inhomogeneities of material properties local to the measurement site.The reason why both types of noise are normally reduced by the use of long base line instruments is explained and a simple, practical long base line tiltmeter is described.  相似文献   

A geochemical study of magmatism associated with the initial stages of back-arc spreading   总被引：4，自引：0，他引：4  

Stephen D. Weaver  Andrew D. Saunders  Robert J. Pankhurst  John Tarney 《Contributions to Mineralogy and Petrology》1979,68(2):151-169

Bransfield Strait is a narrow basin separating the South Shetland Islands from the Antarctic Peninsula and is attributed to recent back-arc extension behind the South Shetland volcanic arc. The volcanic islands of Deception and Bridgeman are situated close to the axis of spreading, whereas Penguin Island lies slightly to the north of this axis. The mineralogy, petrology and geochemistry of the lavas of the three volcanoes have been studied in order to provide information on the nature of magmatism associated with the initial stages of back-arc spreading.Deception Island lavas range from olivine basalt to dacite, and all are highly sodic, with high Na/K, K/Rb, Ba/Rb and Zr/Nb ratios and with Ce_N/Yb_N = 2. Incompatible elements increase systematically between basalt and rhyodacite, while Sr decreases, suggesting that fractional crystallisation is the dominant process relating lava compositions. The rhyodacites have high concentrations of Zr, Y and the REE and negative Eu anomalies and are compositionally similar to oceanic plagiogranite. Bridgeman Island lavas are mostly basaltic andesites, but the levels of many incompatible elements, including REE, are significantly lower than those of Deception lavas, although Ce_N/Yb_N ratios and ⁸⁷Sr/⁸⁶Sr ratios (0.7035) are the same. Penguin Island lavas are magnesian, mildly alkaline olivine basalts with a small range of composition that can be accommodated by fractional crystallisation of olivine, clinopyroxene and/or chromite. Penguin lavas have higher ⁸⁷Sr/⁸⁶Sr (0.7039) and Ce_N/ Yb_N (4) ratios than Deception and Bridgeman lavas. The Rb/Sr ratios of Deception and Penguin basalts (ca. 0.01) are much too low to account for their present ⁸⁷Sr/⁸⁶Sr ratios.Modelling suggests that the source regions of the lavas of the three volcanoes share many geochemical features, but there are also some significant differences, which probably reflects the complex nature of the mantle under an active island arc combined with complex melting relationships attending the initial stages of back-arc spreading. Favoured models suggest that Bridgeman lavas represent 10–20% melting and the more primitive Deception lavas 5–10% melting of spinel-peridotite, whereas Penguin lavas represent less then 5% melting of a garnet-peridotite source. The mantle source for Bridgeman lavas seems to have undergone short-term enrichment in K, Rb and Ba, possibly resulting from dewatering of the subducted slab. Hydrous melting conditions may also account for the more siliceous, high-alumina nature and low trace element contents of Bridgeman lavas.  相似文献   

The geochemistry and petrogenesis of dolerites and gabbros from the Tertiary central volcanic complex of Slieve Gullion,North East Ireland     

John A. Gamble 《Contributions to Mineralogy and Petrology》1979,69(1):5-19

Basaltic magmas emplaced into the root zone of the Slieve Gullion volcano have crystallised to rocks varying in texture from dolerite to gabbro. A mineralogical variation from olivine bearing to quartz bearing varieties has been recorded and with the presence of coexisting Ca-rich and Ca-poor pyroxenes, a tholeiitic assemblage is indicated.Geochemical data confirm this prognosis and a continuous spread of compositions from basalt to tholeiitic andesite are interpreted in terms of fractional crystallisation. Modelling of the fractional crystallisation processes indicate an approach to cotectic conditions with fractionation at low pressures involving olivine, plagioclase, clinopyroxene and Ti-magnetite. Primitive magma compositions, indicated by low values of D.I. and 100 Mg/Mg + Fe²⁺ (atomic)>61, show low concentrations of the large ion lithophile elements such as Rb, Ba, Zr, Y, and K. The relatively high CaO content (>11 %) of these rocks invite comparison with high-calcium low-alkali tholeiitic liquids recognised in extrusive and intrusive magmas elsewhere in the North Atlantic Tertiary volcanic province and with magmas currently erupted at active spreading ridges.In north west Britain the field and stratigraphic distribution of these high-calcium low-alkali magmas suggests that they occupy a distinct chronological niche towards the top of the Palaeocene-Eocene volcanic succession succeeding eruption of mildly alkali and transitional basalts. As such, the refractory (high CaO, MgO, etc.) and large ion lithophile depleted geochemistry can be explained either by differential partial melting in the upper mantle source region or melting of a depleted and refractory mantle source which has already contributed to basalt genesis.  相似文献   

Finite-element analysis of the transport of water and solutes in title-drained soils     

John F. Pickens  Robert W. Gillham  Douglas R. Cameron 《Journal of Hydrology》1979,40(3-4):243-264

The finite-element method based on a Galerkin technique was used to formulate the problem of simulating the two-dimensional (cross-sectional) transient movement of water and solute in saturated or partially saturated nonuniform porous media. The numerical model utilizes linear triangular elements. Nonreactive, as well as reactive solutes whose behaviour can be described by a distribution coefficient or first-order reaction term were considered. The flow portion of the model was tested by comparison of the model results with experimental and finite-difference results for transient flow in an unsaturated sand column and the solute transport portion of the model was tested by comparison with analytical solution results. The model was applied to a hypothetical case involving movement of water and solutes in tile-drained soils. The simulation results showed the development of distinct solute leaching patterns in the soil as drainage proceeded. Although applied to a tile drainage problem in this study, the model should be equally useful in the study of a wide range of two-dimensional water and solute migration problems.  相似文献