Phase relations in a portion of the granite system, KAlSi3O8‐NaAlSi3O8‐SiO2‐H2O have been studied in the pressure range 4 to 10 kb. At 10 kb, melting begins at 625°C at an isobaric invariant point involving albite + orthoclase + quartz + liquid + vapor. The anhydrous composition of the liquid at this isobaric quaternary eutectic corresponds to 21 orthoclase: 56 albite: 23 quartz in contrast to that at the isobaric quaternary minimum at 0.5 kb, where the liquid corresponds to 31 orthoclase: 30 albite: 39 quartz. This represents a shift of the liquid, in anhydrous projection, almost directly toward NaAlSi with increasing P. The quaternary minimum in this system becomes a eutectic at approximately 3.6 kb. Compositional comparisons among granites, aplites, zoned pegmatites, and the quaternary minimum and eutectic suggest that igneous pegmatites and aplites represent magmas that were saturated or nearly saturated with water when they began to crystallize. Trends in bulk composition among pegmatites further suggest selective losses of alkalies during crystallization, probably by diffusion through aqueous fluids coexisting with the silicate melts and their solid products.
In plate tectonic theory, lithosphere that descends into the mantle has a largely derivative composition, because it is produced as a refractory residue by partial melting, and cannot be resorbed readily by the parent mantle. We suggest that lithosphere sinks through the asthenosphere, or outer mantle, and accumulates progressively beneath to form an accretionary mesosphere, or inner mantle. According to this model, there is an irreversible physicochemical evolution of the mantle and its layers. We make the key assumption that the rate at which mass has been transferred from the lithosphere to the mesosphere is proportional to the rate of radiogenic heat production. Calculations of mass transfer with time demonstrate that the entire mass of the present mesosphere could have been produced in geologically reasonable times (3 x 10(9) to 4.5 x 10(9) years). The model is consistent with the generation of the continental crust during the last 3 x 1O(9) years and predicts an end to plate tectonic behavior within the next 10(9) years.
A collaborative study was conducted using a modified AOAC method (sugars in chocolate) for the determination of fructose, glucose, sucrose, and maltose in presweetened cereals by high pressure liquid chromatography (HPLC). Eight samples consisting of 6 products were analyzed in duplicate by the HPLC method and the AOAC Lane-Eynon method. The AOAC method was modified to use water-alcohol (1 + 1) and Sep-Pak C18 cartridges for sample cleanup. The HPLC results indicate precision comparable to the Lane-Eynon method and the chocolate method. The modified HPLC method has been adopted official first action.
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