The Evolving Earth : L.R.M. Cocks (editor) Brit. Museum (Nat. Hist.). Cambridge Univ. Press, Cambridge, 1981, VII + 264 pp., £stg 30.00 (Hardcover),  stg. 10.50 (softcover)     

Martin Schwarzbach 《Tectonophysics》1982,86(4):403-404

  相似文献   

A scheme for computing surface fluxes from mean flow observations   总被引：3，自引：0，他引：3  

Martin I. Hoffert  Joel Storch 《Boundary-Layer Meteorology》1979,17(4):429-442

A computational scheme is developed for estimating turbulent surface stress, sensible heat flux and humidity flux from mean velocity, temperature and humidity at a single height in the atmospheric surface layer; conditions at this reference level are presumed known from observations or from a numerical atmospheric circulation model. The method is based on coupling a Monin-Obukhov similarity profile to a force-restore formulation for the evolution of surface soil temperature to yield the local values of shear stress, heat flux and surface temperature. A self-contained formulation is presented including parameterizations for solar and infrared radiant flux at the surface.In addition to reference-level mean flow properties, the parameters needed to implement the scheme are thermal heat capacity of the soil, surface aerodynamic roughness, latitude, solar declination, surface albedo, surface emissivity and atmospheric transmissivity.Sample calculations are presented for (a), constant atmospheric forcing at the reference level, and (b) variable atmospheric forcing corresponding to Kahle's (1977) measurements of windspeed, air temperature and radiometer soil surface temperature under dry vegetatively sparse conditions in the Mohave Desert in California. The latter case simulated the observed diurnal variations resonably well for the parameters used.Consultant, Atmospheric Sciences Division, Department of Energy and Environment, Brookhaven National Laboratory, Upton, N.Y., pc11973, U.S.A.  相似文献   

Ground retreat and slope evolution on regraded surface-mine dumps,waunafon, gwent     

Martin J. Haig 《地球表面变化过程与地形》1979,4(2):183-189

Ground retreat was monitored on two vegetated and two unvegetated profiles over a five-year period. The average annual retreat of the two unvegetated profiles was 5.84 mm and 3.62 mm; that of the two vegetated profiles 2.34 mm and 2.07 mm. Slope evolution was controlled by the mid-slope-ward migration of two zones of accelerated erosion and the resulting replacement of a central rectilinear slope segment by the upper and lower slope elements.  相似文献   

An investigation of rare-earth mobility: Fenitized quartzites,Borralan complex,N.W. Scotland     

Martin  Robert F.  Whitley  John E.  Woolley  Alan R. 《Contributions to Mineralogy and Petrology》1978,66(1):69-73

Examples of fenitization of pure quartzites provide valuable insight into the relative mobility of elements. This investigation of fenites from the Borralan complex shows that rare-earth elements are mobile and added during fenitization of quartzite. The resulting normalized patterns are distinctive in their enrichment of the light rare earths and steep drops in the interval Nd-Eu. In terms of rare-earth geochemistry, no difference can be found between the sodic and the potassic trends of fenitization at Borralan. Concentrations of mobile elements define straight-line plots through the origin, heretofore considered a criterion indicative of a fractional crystallization process.Present address: Department of Geological Sciences, McGill University, 3450 University Street, Montreal, Que. H3A 2A7, Canada  相似文献   

An event-based stochastic model of phosphorus loading into a lake     

Lucien Duckstein  Istvan Bogardi  Martin Fogel 《Advances in water resources》1978,1(6):321-329

In most lakes, phosphorus (P) is the nutrient controlling the trophic state. Thus, for effective control of eutrophication, the uncertainty in P-loading should be encoded as a probability density function (pdf). Specifically, the pdf of P-loading Y from non-point agricultural sources is sought by means of an event-based stochastic model.P-loading events are triggered by precipitation events (X₁, X₂, T), in which X₁ is the rainfall amount, X₂ the duration, and T the interarrival time between events. (X₁, X₂) are dependent random variables, while T is assumed to be exponentially distributed. The precipitation event causes runoff, which carries dissolved P into the lake with a concentration C₁ and sediment yield, Z, which carries fixed or sorbed P into the lake in a fraction C₂ of Z. Seasonal loading of P is calculated by adding random numbers of random variables. The model accounts separately for dissolved P and sorbed P. Explicit expressions are given for the mean and variance of each type of P-loadings. The case study of a sub-watershed of Lake Balaton, Hungary, is used to illustrate the methodology. Precipitation data, empirical rainfall-runoff-sediment yield relationships and a small number of observations of events are used to calibrate the model and estimate the means and variances of loading per event and per season. Then a simulation method is used to estimate complete pdf of these random variables. Use of the model for alternative methods of controlling P-loading is briefly discussed, as well as the economics of control.  相似文献   

Strontium isotope geochemistry of alpine tectonite lherzolites: Data compatible with a mantle origin     

Martin M. Menzies  V. Rama Murthy 《Earth and Planetary Science Letters》1978,38(2):346-354

Constituent minerals from three alpine lherzolites (Beni Bouchera, Morocco; Lanzo, Italy; and Ronda, Spain) and a clinopyroxene from the Othris complex, Greece, reveal the following range in Sr isotopic composition: clinopyroxenes, 0.70228–0.70370; orthopyroxenes, 0.70265–0.70429; and olivines, 0.70290–0.70831. Collectively the data: (1) indicate that whole-rock lherzolites (weighted recalculations of ⁸⁷Sr/⁸⁶Sr= 0.7025–0.7028) have isotopic compositions which attest to a simple mantle origin and not the complex models proposed to date; (2) are incompatible with the published range for alpine peridotites 0.7063–0.7290; (3) reveal either similar or different isotopic compositions for coexisting minerals, the latter possibly being the result of Rb mobility and introduction of radiogenic Sr into the peridotite system; and (4) indicate the past existence of liquids with “alkalic” affinities within the lherzolite framework. The lherzolites are therefore believed to be residual, having experienced a small degree of partial melting.  相似文献   

Ultramafic inclusions from San Carlos,Arizona: Petrologic and geochemical data bearing on their petrogenesis   总被引：5，自引：0，他引：5  

Frederick A. Frey  Martin Prinz 《Earth and Planetary Science Letters》1978,38(1):129-176

Ultramafic inclusions from San Carlos, Arizona, are classified into two groups. Group I inclusions are dominated by magnesian (Mg/Mg + ΣFe= 0.86 – 0.91), olivine-rich peridotites containing Cr-rich clinopyroxene and spinel. The less abundant Group I pyroxenites (containing Mg- and Cr-rich pyroxenes) occur as discrete inclusions and as portions of composite inclusions where they have a sharp, planar interface with lherzolite. Group II inclusions are dominated by clinopyroxene-rich peridotites containing Al- and Ti-rich augite and commonly abundant, Al-rich spinel. Compared to Group I inclusions, they are more Fe-rich (Mg/Mg + ΣFe= 0.62 – 0.78) and more hetereogeneous in composition and modal proportions. Similar groups occur at many ultramafic inclusion localities.Our petrographic and geochemical results lead to the following conclusions. Olivine-rich Group I inclusions are not genetically related to the host basanite, and they are formed from two components. Component A is a partial melting residue; it comprises the major portion of these inclusions and determines the modal mineralogy and major and compatible trace element composition. Component B results from a small degree (<5%) of garnet peridotite melting (probably, within the low-velocity zone). This highly LIL-element-enriched melt has migrated upwards into the overlying component A where it crystallized primarily as clinopyroxene and amphibole, and thus, introduced LIL elements into the residual component A. Subsequent cooling and subsolidus recrystallization have removed textural evidence of this mixing. This model has also been proposed for olivine-rich Group I inclusions from Victoria, Australia. At Victoria and San Carlos some relatively clinopyroxene-rich Group I lherzolites are not contaminated by component B, and they represent the best estimates of upper mantle composition prior to melting. Group I orthopyroxenites may be fragments of tectonic layers formed in lherzolite, but they could also be early cumulates (now metamorphosed) from the melt in equilibrium with component A. Group I clinopyroxenites have geochemical features of clinopyroxene in equilibrium with a magma. Thus, they could also represent early cumulates (now metamorphosed) from a magma unrelated to the host basanite. Alternatively, their geochemical characteristics could result from more complex models such as residues from partial remelting of pyroxenite dikes and veins or intradike segregation processes such as filter pressing. All Group II inclusions studied appear to be cumulates derived from a SiO₂-undersaturated magma, possibly an early magma in the same volcanic episode which culminated with eruption of the host basanite. The poikilitic texture of amphibole-rich (kaersutite) inclusions is consistent with a cumulate origin. The bulk compositions of Group II inclusions are not equivalent to typical basaltic compositions.  相似文献   

Spinel compositional variation in the crustal and mantle lithologies of the Othris ophiolite     

Martin Menzies 《Contributions to Mineralogy and Petrology》1975,51(4):303-309

Spinels from cumulus and non-cumulus members of the Othris ophiolite display a considerable variation in composition. Cumulus picrites and gabbros contain either a primary chromite and/or a reaction spinel formed by reaction with co-existing silicates (Cr-Al varia tion) or intercumulus liquid (Cr-Fe variation). Non-cumulus peridotites contain spinels which vary along a Cr-Al trend. Harzburgites contain a Cr-spinel and lherzolites a more aluminous spinel. The occurence of gabbroic segregations within the host lherzolite appears to affect the spinel chemistry. Spinels adjacent to these plagioclase—diopside veinlets are richer in aluminium than the spinels scattered within the depleted lherzolite surrounding the veinlet. [Protoclastic harzburgites contain a highly aluminous spinel phase either as an exsolution phase within pyroxenes or as a groundmass spinel.] The Cr-Al variation of the peridotites is believed to have resulted from interaction with interstitial aluminous liquid—in situ basaltic melt from a fused peridotite?  相似文献   

The crystal structure of sarkinite,Mn2AsO4(OH)     

Dr. A. Dal Negro  Dr. G. Giuseppetti  Dr. J. M. Martin Pozas 《Mineralogy and Petrology》1974,21(3-4):246-260

Summary Sarkinite is a basic manganese arsenate, Mn₂AsO₄(OH). The lattice parameters are:a=12.779 (2) Å,b=13.596 (2) Å,c=10.208 (2) Å, =108°53 (6). Space groupP2₁/a,Z=16. The crystal structure has been solved by direct methods from three-dimensional X-ray diffractometer data and refined by least-squares methods toR=0.052 for 3519 independent reflections. The crystal structure is built up by a three-dimensional framework of MnO₄(OH)₂ octahedra, MnO₄(OH) trigonal bipyramids and AsO₄ tetrahedra, as found in wagnerite. Isotypy of sarkinite with triploidite is confirmed.

---

Die Kristallstruktur des Sarkinits, Mn₂AsO₄(OH)

Zusammenfassung Die Kristallstruktur des basischen Manganarsenates Sarkinit, Mn₂AsO₄(OH), mit den Gitterkonstantena=12,779 (2) Å,b=13,596 (2) Å,c=10,208 (2) Å, =108°53 (6). RaumgruppeP2₁/a,Z=16, wurde mit dreidimensionalen Röntgendiffraktometermessungen durch direkte Methoden gelöst und nach dem kleinste-Quadrate-Verfahren verfeinert (R=0,052 für 3519 unabhängige Reflexe). Die Struktur besteht aus einem dreidimensionalen Gerüst aus MnO₄(OH)₂-Oktaedern, trigonalen Bipyramiden von MnO₄(OH) und AsO₄-Tetraedern wie in Wagnerit. Die Isotypie von Sarkinit mit Triploidit wurde bestätigt.

---

---

With 1 Figure  相似文献   

Induction of abnormal polychaete larvae by heavy metals     

D.J. Reish  F. Piltz  J.M. Martin  J.Q. Word 《Marine pollution bulletin》1974,5(8):125-126

A little known observation that exposure to sublethal concentrations of detergent cause fatal abnormalities in the second generation of a polychaete has been followed up and similar abnormalities have been observed in the first or second generation of larvae exposed to sublethal concentrations of copper and zinc. Few toxicity tests extend beyond the responses of the exposed individuals. The discovery of a delayed reaction to sublethal concentrations of common contaminants of the sea has unknown but potentially important ecological implications.  相似文献