Behavior and effects of phosphorus in the system Na2O−K2O−Al2O3−SiO2−P2O5−H2O at 200 MPa(H2O)

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.     

In situ vane system for seafloor strength investigations

The In Situ Vane (ISV) system has been developed to determine the strength profile within the upper 1.5 m of deep sea clays. The system is designed to operate in 6000-m water depth after one-year dormancy on the bottom and consists of four integrated packages; controller and data acquisition system, mechanical system, volume compensator, and power supply. This paper describes development of a prototype which was used under a pressure of 550 bars after a 30-day dormancy and of the full system which was successfully used in a deep water (5800 m) test. In the first full application of the system the ISV will be used to measure changes in sediment strength caused by high temperature (300degC) as part of the U.S. Subseabed Disposal Program.     

Feasibility of interferometric swath bathymetry using GLORIA, along-range sidescan

The feasibility of adding an interferometric swath bathymetric system to GLORIA, a 6.6 kHz long-range sidescan sonar, is discussed. The size of GLORIA's low-frequency transducer arrays and towfish precludes significant modifications, but even without such changes bathymetric errors could be several tens of metres over a usable swath somewhat smaller than the normal GLORIA swath. A swath bathymetry based on GLORIA will have random errors depending strongly on wind speed, water depth, and swath width. Within the range of these parameters, root-mean-square bathymetry errors in the range of 1-100 m can be expected     

On the Utility of ENSO and PNA Indices for Long-Lead Forecasting of Summer Weather over the Crop-Growing Region of the Canadian Prairies

Summary The well known ENSO (El Ni?o-Southern Oscillation) phenomenon is quantitatively identified in terms of SST (sea surface temperature) anomalies over the equatorial central and eastern Pacific and sea level pressure difference over eastern and western regions of the equatorial Pacific. The PNA (Pacific North American) atmospheric flow pattern, originally identified by Wallace and Gutzler (1981) is representative of a certain preferred configuration of the mid-tropospheric geopotential height field in the longitudinal sector extending from the mid-Pacific to the southeastern United States. The PNA index is defined as a linear combination of normalized geopotential height anomalies at the 700 mb level at four selected locations. Using multiple regression analysis, suitable linear combinations of predictors based on monthly values of ENSO and PNA indices are obtained which can foreshadow the summer season’s weather over the crop-growing region of the Canadian prairie provinces with a lead time of 2 to 7 months. The utility of the ENSO and PNA indices for advance indication of summer weather with implications for grain yields over the Canadian prairies is further discussed. Received September 10, 1996 Revised October 13, 1997