Nickel partitioning between olivine and liquid in natural basalts Henry's law behavior—Reply to B.O. Mysen     

Peter I. Nabelek 《Earth and Planetary Science Letters》1981,52(1):225-226

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Discussion of “Thermodynamic parameters of CaMgSi2O6-Mg2Si2O6 pyroxenes based on regular solution and cooperative disordering models” by Holland,Navrotsky, and Newton     

Donald H. Lindsley  Paula M. Davidson  T. J. B. Holland  A. Navrotsky  R. C. Newton 《Contributions to Mineralogy and Petrology》1981,75(3):301-306

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Nontidal circulation and mixing processes in the lower Potomac estuary     

Andrew D. Hamilton  Robert E. Wilson 《Estuaries and Coasts》1980,3(1):11-19

An analysis of the vertical structure of nontidal longitudinal currents and salinity in a reach of the lower Potomac River Estuary suggests that values for vertical eddy viscosity and eddy diffusivity scale with water depth H, tidal current amplitude U and bulk Richardson number according to conventional empirical formulas. However, the constant which relates the vertical eddy coefficients under conditions of neutral stability to UH is found to be an order of magnitude less than that expected for tidal conditions. Analyses also suggest that the degree of enhancement of longitudinal dispersion by the shear effect associated with the nontidal currents is a strong function of bulk Richardson number.  相似文献   

Chemical characteristics of island-arc basalts: Implications for mantle sources   总被引：3，自引：0，他引：3  

M.R. Perfit  D.A. Gust  A.E. Bence  R.J. Arculus  S.R. Taylor 《Chemical Geology》1980,30(3):227-256

Major-element, trace-element and isotopic compositions of approximately 1200 basalts (< 53 wt. % SiO₂) from intra-oceanic island arcs have been compiled to assess the nature and possible sources of primitive island-arc basalts (IAB). The chemical characteristics of IAB are examined with reference to those of mid-ocean ridge basalts (MORB) and intraplate oceanic basalts (IPB). Major-element compositions of primitive [$\text{Mg}\text{(}\text{Mg +Fe}{}^{\mathrm{2+}}\text{)}\text{> 65}$] IAB and MORB are similar, but differ significantly from IPB. In general, IAB do not have higher Al₂O₃, lower TiO₂ or a lack of Fe enrichment compared to primitive MORB but many do have greater K₂O contents. Differences in major- and minor-element contents between more evolved IAB and MORB result from the dominance of plagioclase + olivine crystal fractionation in MORB magmas vs. clinopyroxene + olivine controlled fractionation in IAB suites. This difference in crystallization history may be related to the higher P_H2O or greater depth of crystallization of IAB magmas compared to those inferred for MORB.IAB are characteristically enriched in large-ion-lithophile (LIL) elements and depleted in high-field-strength ions (e.g., Zr, Nb and Hf) relative to normal MORB (N-type) and IPB. The enrichment of some LIL elements (e.g., Sr, Rb, Ba and Pb) relative to the rare-earth elements in IAB is difficult to explain by simple partial melting alone and suggests a multistage petrogenesis involving an LIL-enriched component. Low abundances of high-field-strength ions in evolved IAB are explicable in terms of fractional crystallization, but the cause for consistently low abundances in primitive IAB remains problematic.Island-arc lavas contain greater concentrations of volatiles and have higher $\text{CO}{}_2\text{H}{}_2\text{O}$ and Cl/F ratios than either MORB or IPB, suggesting involvement of a slab-derived volatile component. However, this is not consistent with ${}^3\text{He}{}^4\text{He}$ data which indicate that only near-trench volcanics have been significantly affected by dehydration of the oceanic crust.Sr-, Nd-, Pb- and O-isotopic data, in conjunction with the trace-element data, clearly indicate that IAB are derived from heterogeneous, LIL-depleted mantle sources most similar to those which give rise to enriched MORB (E-type). The marked shift towards higher ${}^{87}\text{Sr}{}^{86}\text{Sr}$ in IAB compared to oceanic lavas with similar ${}^{143}\text{Nd}{}^{144}\text{Nd}$ values cannot be explained simply by the addition of radiogenic Sr from the slab. Variable degrees of contamination from a crustally-derived sedimentary component is consistent with the isotopic and trace-element data from a number of arcs. However, the lack of correlation between LIL/REE ratios and more radiogenic isotopic ratios suggests that this enrichment/contamination process is complex. A multi-stage petrogenetic model involving subducted oceanic crust (± sediments), dehydration/volatile transfer, and partial melting of metasomatized mantle beneath island arcs is considered the most reasonable, although least constrained, method to generate a variety of primitive IAB.  相似文献   

Stability of titanian clinohumite: Experiments and thermodynamic analysis   总被引：2，自引：0，他引：2  

Martin Engi  Donald H. Lindsley 《Contributions to Mineralogy and Petrology》1980,72(4):415-424

Reversed hydrothermal experiments on a natural titanoclinohumite [Ti-Cl; approximate formula Mg_7.5FeTi_0.5O₁₆(OH)] show that it breaks down at 475°±11° C (3.5 kbar), 620°±11° C (14 kbar) and 675°±8° C (21 kbar) to the assemblage olivine +ilmenite+vapor. An internal-consistency analysis of the data yields _r G _s ^/0 (298 K, 1 bar)=36,760±3,326 cal (mole Ti-Cl)^–1. _r S _s ^/0 (298 K, 1 bar)=34.14±5.91 cal deg^–1(mole Ti-Cl)^–1. Linear correlation coefficient r _G–S 1.0. A solution model that accounts for TiO₂-M(OH)₂ and F-OH substitution shows that the results for our nearly F-free Ti-Cl are in reasonable agreement with the unreversed breakdown experiments of Mer-rill et al. (1972) on a F-bearing Ti-Cl.Because fluorine is necessary to stabilize Ti-Cl under mantle conditions, we suggest that Ti-Cl is much more likely to be a storage device for fluorine than for water in the mantle.  相似文献   

Southern Oscillation simulation in the OSU coupled upper ocean-atmosphere GCM     

Kenneth R Sperber  Sultan Hameed 《Climate Dynamics》1991,6(2):83-97

The Southern Oscillation is a major component in the interannual variations of global climate. The Oregon State University global climate model, with a dynamically interactive upper ocean, reproduces in qualitatively correct fashion some of the major characteristics of the Southern Oscillation. This model simulates the observed anti-correlation of annually averaged sea-level pressure (SLP) between the eastern Pacific and the Indonesian region, the primary atmospheric signal of the Southern Oscillation. In the composite of the simulated warm events positive sea-surface temperature (SST) anomalies expand eastward towards South America from the tropical western Pacific during the first half of the calendar year. The SST anomalies develop in conjunction with eastward mixed layer current anomalies in the tropical Pacific. In the late summer and early fall anomalously warm water near South America develops and moves westward to merge with the central Pacific anomalies. This lagged development in the eastern Pacific is analogous to the evolution of the 1982/83 and 1986/87 El Ninos. The temperature of the thermocline layer also increases, with the slope of the equatorial Pacific thermocline decreasing in response to the relaxation of the surface forcing. Enhanced precipitation occurs in the mid-Pacific while in the Indian and Australian monsoon regions a deficit occurs. The peak of the warm phase occurs in late northern fall/early winter, somewhat earlier than during observed El Ninos. The cold phase of the Southern Oscillation, enhancement of the zonal circulation, evolves in a fashion similar to the warm phase with the signs of the anomalies reversed, similar to observations. Occurrence of Southern Oscillation in this coarse resolution GCM indicates that high resolution ocean waves do not play a crucial role in the generation of this phenomenon as suggested by Pacific basin models. These results also show that ocean-atmosphere global climate models are useful tools for investigation of time dependent changes on the interannual timescale in addition to their hitherto accepted use for studying equilibrium properties of climate.  相似文献   

Multilayer Sampling in the Water-Table Region of a Sandy Aquifer     

Edward Kaplan  Sujit Banerjee  Daniel Ronen  Mordeckai Magaritz  Albert Machlin  Michael Sosnow  Eric Koglin 《Ground water》1991,29(2):191-198

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Boundary skin friction and sediment transport about an animal-tube mimic   总被引：6，自引：0，他引：6  

James E.  Eckman†Arthur R. M.  Nowell‡ 《Sedimentology》1984,31(6):851-862

ABSTRACT
A flume study was made of fluid flow, boundary skin friction, and sediment transport about an animal-tube mimic. The effect of a tube on momentum transfer depends most strongly on its height. A tube increases the net boundary skin friction locally and tends to promote sediment entrainment near its base. Flow in this region appears to be governed by the same similarity laws that apply to cylinders with much larger body Reynolds number. Particles travelling as suspended load may be deposited immediately downstream of the tube. The net sedimentological effect of any tube (i.e. deposition or scour) will depend both on its height and on the boundary shear stress imposed by the external flow. The near-wake region of a tube is dominated by a strong cross-stream exchange of momentum. Wake perturbations decay downstream seemingly in accordance with similarity laws which also govern mounted, two-dimensional structures.  相似文献   

Experimentally determined compositions of diopside-jadeite pyroxene in equilibrium with albite and quartz at 1200–1350°C and 15–34 kbar     

Tibor Gasparik 《Geochimica et cosmochimica acta》1985,49(3):865-870

Equilibrium compositions of diopside-jadeite pyroxene coexisting with albite and quartz were experimentally determined at 25 different P-T conditions, using an electron microprobe for analysis. The new data and the 600°C data of Holland (1983) provided the following mixing properties of the diopside (Di)-jadeite (Jd) solid solution (J, K): G^xs = X_JdX_Di[12600 ? 9.45T + (12600 ? 7.6T)(X_Jd ? X_Di) ? (21400 ? 16.2T)(X_Jd ? X_Di)²]. The Di-Jd solution is close to ideal above 1000°C but immiscible below 565°C. The Di-Jd solvus is slightly asymmetric with the crest at composition Di_42.4Jd_57.6. Excess enthalpy is positive but smaller than indicated by the enthalpy of solution measurements of Woodet al. (1980). Disorder in the Di-Jd solution is significantly smaller than complete disorder implied by the ionic two-site model.  相似文献   

Texture and structural interpretation of the alteration of pyroxene to other biopyriboles     

Yoshiharu Nakajima  Paul H. Ribbe 《Contributions to Mineralogy and Petrology》1982,78(3):230-239

In a metamorphosed gabbro from Hokkaido, Japan, augite containing exsolved orthohypersthene and minor pigeonite has been altered to a variety of biopyriboles. High resolution transmission electron microscopy of slightly altered augite shows only narrow (010) lamellae of clinoamphibole which always contain even numbers of double chains. In more highly altered regions, all three pyroxenes are changed to double-, triple- and more highly polymerized multiple-chain biopyriboles, with chlorite d ₀₀₁ 14.5 Å) found only in orthopyroxene. Several (010) lamellae containing only one double chain have been observed, and their textural relationship to the surrounding single-chain host may explain how the rotated domains of biopyribole initially attain their orientation in the host pyroxene.A structural model is proposed for the polymerization of single chains in the tetrahedral layers of pyroxene which involves small movements of oxygens and tetrahedral atoms (Si, Al) with a minimum of bond breaking and re-forming, concommitant with hydroxylization of certain oxygens and the diffusion of Mg, Fe and/or Ca along the rift in the octahedral layer.  相似文献