Editor''s note     

C. John Mann 《Mathematical Geology》1990,22(2):149

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The Little Ice Age : By Jean Grove. Methuen Publishers, London/New York, 498 pp     

Daniel H. Mann 《Quaternary Research》1990,34(3)

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The compressibility of silicate liquids containing Fe2O3 and the effect of composition,temperature, oxygen fugacity and pressure on their redox states     

Victor C. Kress  Ian S. E. Carmichael 《Contributions to Mineralogy and Petrology》1991,108(1-2):82-92

Ultrasonic longitudinal acoustic velocities in oxidized silicate liquids indicate that the pressure derivative of the partial-molar volume of Fe₂O₃ is the same in iron-rich alkali-, alkaline earth- and natural silicate melt compositions at 1 bar. The dV/dP for multicomponent silicate liquids can be expressed as a linear combination of partial-molar constants plus a positive excess term for Na₂O−Al₂O₃ mixing. Partial-molar properties for FeO and Fe₂O₃ components allow extension of the empirical expression of Sack et al. (1980) to permit the calculation of Fe-redox equilibrium in a natural silicate liquid as a function of composition, temperature, fo₂ and pressure; a more formal thermodynamic expression is presented in the Appendix. The predicted equilibrium fo₂ of natural silicate melts, of fixed oxygen content, closely parallels that defined by the metastable assemblage fayalite+magnetite+β-quartz (FMQ), in pressure-temperature space. A silicate melt initially equilibrated at 3 GPa and FMQ, will remain within approximately 0.5 log₁₀ units of FMQ during its closed-system ascent. Thus, for magmas closed to oxygen, iron-redox equilibrium in crystal-poor pristine glassy lavas represents an excellent probe of the relative oxidation state of their source regions.  相似文献   

Rates of surface processes on slopes,slope retreat and denudation: A reply     

Ian Saunders  Anthony Young 《地球表面变化过程与地形》1985,10(1):85-86

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Editor's note     

C. John Mann 《Mathematical Geosciences》1985,17(8):853-853

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Algal uptake of U and some other metals: Implications for global geochemical cycling     

H. Mann  W.S. Fyfe 《Precambrian Research》1985,30(4):337-349

Freshwater green algae Ankistrodesmus sp, cultured in dilute solutions of metals chelated with EDTA, revealed massive uptake of U. Examination of Thames River waters and selected micro-organisms of its aquatic ecosystem revealed an average dissolved U concentration of 1.46 ppb, representing about twice the global mean riverine solute concentration of 0.6 ppb U. Suspended particulates, principally algae, contain U at 10³ to 10⁵ times that of their river habitat, averaging 28 300 ppb U. One community of the filamentous algae Spirogyra sp. contained intracellular crystals tentatively identified as the Ca-oxylate weddelite. Studies of algae from a variety of environments have shown large concentration factors for a wide range of elements. Algae from an acid U mine tailings site contain up to 2.7% U (dry weight) plus very high concentrations of other metals. Micro-organisms may act as an important sink for metal solutes in the hydrosphere.  相似文献   

Relationships among dissolved organic matter,iron, and discharge in a moorland stream     

Ian C. Grieve 《地球表面变化过程与地形》1984,9(1):35-41

Dissolved organic matter (DOM) and iron in a moorland stream were determined at 8-hour intervals over a 6-month period to examine relationships with streamflow. Regression of both solutes on discharge were positive and explained 50–70 per cent of the variance in the solute data, but better predictions were obtained in both cases when a covariate reflecting temporal variation in the relationships was introduced (explained variance 80–90 per cent). Variations in the regression of Fe on DOM were also identified, indicating differences in the complexing power of DOM for Fe and possible variations in the chemical composition of the DOM.  相似文献   

Characteristics and origins of lee-side stratification sequences in late pleistocene drumlins,northern Ireland     

George F. Dardis  A. Marshall McCabe  W. Ian Mitchell 《地球表面变化过程与地形》1984,9(5):409-424

Spindle- and parabolic-shaped drumlins examined at fifty-five localities in northern Ireland possess stratification sequences on their lee-side flanks. These forms lack the distinctive steep stoss- and tapering lee-ends of classical drumlins and tend to occur in linear zones transverse to late Pleistocene ice-flow. In most cases (90 per cent) the stratified deposits infill embayments excavated in the lee-side of barkhanoid forms and, in the remainder (10 per cent), they are superimposed on the lee-side of whaleback forms. The stratification sequences developed as a result of sedimentation in interconnected subglacial water-filled cavities and are unlike remanie proglacial sediments moulded by ice into drumlin form. Stratigraphic evidence indicates that the lee-side sequences developed during drumlin streamlining, which supports the view that subglacial hydraulic processes played an important role in drumlin formation.  相似文献   

Atmospheric effects from post-nuclear fires     

Paul J. Crutzen  Ian E. Galbally  Christoph Brühl 《Climatic change》1984,6(4):323-364

During a large nuclear war, the atmosphere would be loaded with huge quantities of pollutants, which are produced by fires in urban and industrial centers, cultivated lands, forests and grasslands. Especially detrimental are the effects of light absorbing airborne particles. An analysis of the amounts of the various types of fuels which could burn in a nuclear war indicates that more than 10¹⁴ g of black smoke could be produced by fires started by the nuclear explosions. Due to this, the penetration of sunlight to the earth's surface would be reduced greatly over extended areas of the northern hemisphere, maybe even globally. This could temporarily cause extreme darkness in large areas in midlatitudes and reduce crop growth and biospheric productivity.This situation would last for several weeks and cause very anomalous meteorological conditions. Much solar radiation would be absorbed in the atmosphere instead of at the earth's surface. The land areas and lower atmosphere would, therefore, cool and the overlying atmosphere warm, creating strong vertical thermal stability in a highly polluted atmosphere. For extended periods and in large parts of the world, weather conditions would be abnormal. The resulting cold, probably freezing, temperatures at the ground would interfere severely with crop production during the growing season and cause extreme conditions for large sections of the biosphere. The combination of lack of sunlight, frost and other adverse meteorological conditions would add enormously to the already huge problems of the survivors.  相似文献   

Finite strains from non-coaxial strain paths. I. Computational techniques     

Patrick J. Shore  Ian J. Duncan 《Tectonophysics》1984,110(1-2)

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