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1.
ACOSTA-VIGIL ANTONIO; LONDON DAVID; DEWERS THOMAS A.; MORGAN GEORGE B. VI 《Journal of Petrology》2002,43(10):1885-1908
The mechanisms and kinetics of equilibration between peraluminousminerals and granitic melt were investigated experimentallyby the dissolution of corundum and andalusite into H2O-saturatedmetaluminous haplogranitic melt at 800°C and 200 MPa. Mineraland haplogranitic glass rods were juxtaposed inside platinumcapsules, and then subjected to experimental conditions fortimes ranging from 12 to 2900 h. Upon melting, the mineral meltinterface retreats with the square root of time. The compositionof the melt at the interface changes with time, but its ASI[aluminum saturation index = molar Al2O3/(CaO + Na2O + K2O)]remains constant at 相似文献
2.
Morozov E. G. Frey D. I. Polukhin A. A. Krechik V. A. Artemiev V. A. Gavrikov A. V. Kasian V. V. Sapozhnikov F. V. Gordeeva N. V. Kobylyansky S. G. 《Oceanology》2020,60(5):573-588
Oceanology - Results of a mesoscale survey in the Powell Basin in the northern part of the Weddell Sea are analyzed. The survey included 24 CTD casts (6 × 4) with an interval of six nautical... 相似文献
3.
Antonio?Acosta-Vigil David?LondonEmail author George?B.?Morgan VI 《Contributions to Mineralogy and Petrology》2005,149(3):276-287
This study examines hydration–diffusion in the metaluminous haplogranite system at 200 MPa H2O and 800–300°C. At 800°C hydration is accompanied by melting and uphill diffusion of sodium from anhydrous glass toward the region of hydration and melting, whereas potassium diffuses away from the hydration front and into anhydrous glass. Silicon and aluminum are simply diluted upon hydration. There is no change in molecular Al/(Na + K) throughout the entire hydration-diffusion aureole and, therefore, (1) there is no loss of alkalis to the vapor, and (2) K migrates to replace Na in order to maintain local charge balance required by IVAl. Alkali diffusion occurs over a viscosity contrast from 104.1 Pa s in hydrous liquid to 1011.8–1013.5 Pa s in anhydrous glass. From these results, we interpret that: (1) Na is structurally or energetically favored over K as a charge-balancing cation for IVAl in hydrous granitic liquids, whereas the opposite behavior has been observed for anhydrous melts, and (2) the diffusion of alkalis through silicate melts is largely independent of viscosity. Results from 600°C are similar to those at 800°C, but hydration at 300°C involves a loss of Na and concomitant increase in molar Al/(Na + K) in the hydration zone due to hydrogen-alkali exchange between fluid and glass. Hydration behavior at 400°C is transitional between those at 300°C and 600°C, suggesting that the change in hydration mechanism occurs near the glass transition. 相似文献
4.
The influence of the sea surface temperature (SST) on the carbon dioxide (CO2) exchange with the atmosphere at different spatial and temporal scales, which has a multidirectional character, was studied. The initial data included the monthly averages of the CO2 flux during the period of 1982–2011 at grid nodes of 4° by latitude and 5° by longitude, as well as the SST satellite data from January 1, 1982 to December 31, 2012 at the geographical grid nodes of 0.25° × 0.25°. Statistical models of estimation of the resulting global CO2 flux were suggested on the basis of data on SST anomalies. It is demonstrated that the SST variations in the equatorial zone mostly control the interannual fluctuations of the resulting CO2 flux in the ocean-atmosphere system. 相似文献
5.
V. I. Gordeeva L. Sh. Bazarov E. I. Petrushin 《Journal of Volcanology and Seismology》2011,5(2):114-122
The morphology and internal convective structure of continuous roll flows in magma melts were experimentally studied with
regard to peripheral (shallow) magma chambers and downgoing circular gravity flows in conduits. We found properties of continuous
convective mixing in a magma melt in a peripheral chamber due to convective roll flows. We investigated the mechanism that
is responsible for cumulus generation at the bottom of a peripheral chamber when homogeneous and heterogeneous melts are emplaced.
We conducted an experimental study of how the contact surface is formed at the cumulus-melt boundary. We made a qualitative
study of the mechanism that affects the composition of magma melts over time in a peripheral and a mantle (deeper) chamber
owing to crystallization, as well as the special mechanism that is responsible for cumulus generation in the peripheral chamber. 相似文献
6.
Crystallization of the Little Three layered pegmatite-aplite dike, Ramona District, California 总被引:5,自引:4,他引:1
Subhorizontally layered pegmatite-aplite bodies are characterized by fine-grained, sodic to granitic aplite that is usually
juxtaposed abruptly above by much coarser-grained, commonly graphic potassic pegmatite. Although well studied, there currently
is little concensus as to how such dikes form. The Little Three dike near Ramona, California, is representative of such zoned
bodies in this and other regions, and contains discontinuous miarolitic pockets near the base of the graphic pegmatite zone.
Tourmaline, garnet, biotite, and muscovite show no changes in major- or minor-element compositions indicative of progressive
magmatic fractionation until the immediate vicinity of the main miarolitic zone, where they record abrupt and extreme enrichments
in Li, F, and Mn. There is no correlation of chemical changes in the dike with the appearance of small miarolitic vugs well
below the main miarolitic zone, nor is there any indication that the aplite, graphic pegmatite, or miarolitic pockets represent
separate magma injections. The chemistries of tourmaline, garnet, and micas, however, preclude conventional models of Rayleigh
fractionation or traditional zone refining. Textural features and modeled cooling histories indicate that the dike cooled
quickly and might have solidified partially or totally to glass before crystallization commenced. Geothermometry based on
the compositions of coexisting plagioclase and homogeneous, nonperthitic K-feldspar indicates inward crystallization of the
dike, from ∼400–435 °C at the margins to ∼350–390 °C within 20–30 cm of the pocket horizon, then a sharp decrease to 240–275 °C
in the pockets where K-feldspar is perthitic. We interpret the feldspar geothermometry (except perhaps in the miarolitic cavities)
to reflect the temperatures at crystallization fronts that advanced into the pegmatite, first from the foot wall and eventually
joined by a similar front downward from the hanging wall. Crystallization down from the hanging wall may have commenced after
∼70–80% of the foot wall aplite had crystallized. The very abrupt increases of Li, Mn, and F in tourmaline and garnet near
the miarolitic zone appear to be explained best by the process of constitutional zone refining, in which a fluxed crystallization
front sweeps an incompatible element-enriched boundary layer through a solid or semi-solid. After these two highly fluxed
boundary layers merged near the main miarolitic zone, compositional evolution could have proceeded by crystal-melt fractionation.
Received: 24 March 1998 / Accepted: 10 March 1999 相似文献
7.
Behavior and effects of phosphorus in the system Na2O−K2O−Al2O3−SiO2−P2O5−H2O at 200 MPa(H2O) 总被引:1,自引:1,他引:1
David London George B. Morgan VI Harold A. Babb Jennifer L. Loomis 《Contributions to Mineralogy and Petrology》1993,113(4):450-465
The addition of phosphorus to H2O-saturated and initially subaluminous haplogranitic (Qz–Ab–Or) compositions at 200 MPa(H2O) promotes expansion of the liquidus field of quartz, a marked decrease of the solidus temperature, increased solubility limits of H2O in melt at low phosphorus concentrations, and fractionation of melt out of the haplogranite plane (projected along an Or28 isopleth) toward a peralkaline, silica-poor but quartz-saturated minimum composition. The partition coefficient for P2O5 between aqueous vapor and melt with an ASI (aluminum saturation index, mol Al/[mol Na+K])=1 is negligible (0.06), and consequently so are the effects of phosphorus on other melt-vapor relations involving major components. Phosphorus becomes more soluble in vapor, however, as the concentration of a NaPO3 component increases via the fractionation of melt by crystallization of quartz and feldspar. The experimental results here corroborate existing concepts regarding the interaction of phosphorus with alkali aluminosilicate melt: phosphorus has an affinity for alkalis and Al, but not Si. Phosphorus is incorporated into alkali feldspars by the exchange component AlPSi-2. For subaluminous compositions (ASI=1), the distribution coefficient of phosphorus between alkali feldspar and melt, D[P]Af/m, is 0.3. This value increases to D[P]Af/m=1.0 at a melt ASI value of 1.3. The increase in D[P]Af/m with ASI is expected from the fact that excess Al promotes the AlPSi-2 exchange. With this experimental data, the P2O5 content of feldspars and whole rocks can reveal important facets of crystallization and phosphorus geochemistry in subaluminous to peraluminous granitic systems. 相似文献
8.
We consider the interannual variability of the intensity of the Gulf Stream and interannual fluctuations of seawater parameters in the Gulf Stream and in the Labrador Current during intense climate warming. We show that this intensity has increased during this period. The scales of fluctuations and their contribution to variance in the initial time series was determined from wavelet analysis of the Gulf Stream north wall. We noted a considerable decrease in water density of the main branch of the Gulf Stream, caused by the increase in temperature due to global climate warming, and an absence of trends in water density of the main branch of the Labrador Current. 相似文献
9.
Water Resources - The interaction between hydrological cycle components in the ocean–atmosphere–land system was considered. Calculations were made with the use of various reanalysis... 相似文献
10.
David London Richard L. Hervig George B. Morgan VI 《Contributions to Mineralogy and Petrology》1988,99(3):360-373
Vapor-saturated experiments at 200 MPa with peraluminous, lithophile-element-rich rhyolite obsidian from Macusani, Peru, reveal high miscibility of H2O and silicate melt components. The H2O content of melt at saturation (11.5+-0.5 wt.%) is almost twice that predicted by existing melt speciation models. The corresponding solubility of melt components in vapor decreases from 15 wt.% dissolved solids (750°–775° C) to 9 wt.% at 600° C. With regard to major and most minor components, macusanite melt dissolves congruently in vapor. Among the elements studied (B, P, F, Li, Rb, Cs, Be, Sr, Ba, Nb, Zr, Hf, Y, Pb, Th, U, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm), only boron has a vapor/melt partition coefficient (D[B]) consistently 1 at superliquidus temperatures (>645° C). Phosphorus and fluorine behave similarly, with D[P] and D[F]<0.5. Little or no significant vapor/melt fractionation is evident among most periodic groups (alkalis, alkaline earths, Zr/Hf, or the REE). The temperature dependence of vapor/melt partition coefficients is generally greatest for cations with charge +3 (except Nb and U); most vapor/melt partition coefficients for trace elements increase with decreasing temperature to the liquidus. Crystallization proceeds by condensation of crystalline phases from vapor; most coexisting melts are aphyric. Changes in the major element content of melt are dominated by the mineral assemblage crystallized from vapor, which includes subequal proportions of white mica, quartz, albite, and orthoclase. The volumetric proportion of (mica + or-thoclase)/albite increases slightly with decreasing T, creating a sodic, alkaline vapor. Vapor deposition of topaz (T500° C), which consumes F from melt, returns K/Na ratios of melt to near unity with the vapor-deposition of albite. The abundances of most trace elements in residual melt change little with the crystallization of major phases, but in some cases are strongly controlled by the deposition of accessory phases including apatite (T550° C), which depletes the melt in P and REE. Below the liquidus, boron increasingly favors the vapor over melt with decreasing temperatures. 相似文献