Silica variation

Kennedy, V. C. 1971. Silica variations in stream water with time and discharge. In Nonequilibrium systems in natural-water chemistry, Adv. Chem. Ser. 106, pp. 94-130. Washington, DC Am. Chem. Soc. 

Silica Variation in Stream Water with Time and Discharge... 

Silica concentration in the Mattole River displays a consistent pattern with respect to stream flow, specific conductance, and sediment concentration. However, the silica variation is out of phase with respect to both discharge and dissolved electrolytes, and silica varies inversely with sediment concentration. Any explanation of the silica variation must account for these facts. 

The fact that the pattern of silica variation in Conklin Creek is very similar to that in the Mattole River, even though the stream basins are different by a factor of about 40 in size, indicates that the observed variation in the Mattole basin is not owing to travel time effects. 

There is little correlation between silica concentration and discharge of Pescadero Creek (Figure 17). When the silica concentration, the ratio of Si02 Spec. Cond., and water discharge are plotted against time for a storm period (Figure 18), one can see that the silica variation and the... 

Surface activity a Activated silica Deactivated silica Variation in a with increase in silica activation temperature (150-400 )... 

Linear capacity" Activated silica Deactivated silica Variation of sample selectivity (relative K° values)... 

Fig. 6.14 Silica-variation diagrams of the silicic porphyries of the Wyatt Formation and of the Ackerman Formation in the La Gorce Mountains and in the upper Scott Glacier area (Data by Stump et al. 1986 Minshew 1967)...

In addition, the rocks of both formations are peraluminous because their molar ratios of AI2O3/ (K O + Na O + CaO) are greater than 1.0 in all samples analyzed by Stump et al. (1986). The silica-variation diagrams in Fig. 6.14 suggest that the concentrations of the major rock-forming elements were affected by fractional crystallization of the respective parent magmas. 

Fig. 7.5 Silica-variation diagram of whole-rock samples of the Wyatt Formation in the Wisconsin Range of the Horlick Mountains. The x represents a sample of the porphyritic quartz monzonite (Data from Minshew 1967 Faure unpublished in Appendix 7.8.1)...

Eastin (1970) also reported the chemical analyses in Appendix 8.5.14 of seven samples of the Gambacorta Formation provided by D.L. Schmidt. Silica-variation diagrams in Fig. 8.13 indicate that the concentrations of alkali metals, alkaline earths, and oxides of iron vary regularly with increasing silica concentrations from 72% to 78%. The only sample that deviates from the smooth trends ( 294) is a pyroclastic rhyolite clast from the basal part of the Elliott Sandstone (Pemberton Section) 1.6 km west of Wiens Peak. The Elliott... 

Fig. 8.14 These silica variation diagrams support the conjecture that the Serpan Gneiss formed as a border facies of the magma of the Serpan Granite that was contaminated by assimilating rocks of the Patuxent Formation. Consequently, these bodies of plutonic igneous rocks have the same age but different Rb/Sr ratios. A straight line fitted to these samples in a Rb-Sr isochron diagram is a mixing line that cannot be used to calculate the age of these rocks. The chemical analyses of these rocks were provided by D.L. Schmidt to Eastin (1970)...

Precipitated silica (silica P) abrasive SiOj have been introduced in toothpaste formulation in the 1970s. They are synthetic, noncrystaUine, or amorphous silica. They represent -80% of the world production of synthetic amorphous silica. Variation in the particle size allows the control of the abrasivity and the thickness of the product. Amorphous silica is obtained by reaction of a sodium silicate solution at pH >7 with an add such as H2SO4 or HCl, according to the following reaction ... 

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