Growth zoning

The obvious application of microfocus Raman spectroscopy is the measurement of individual grains, inclusions, and grain boundary regions in polycrystalline materials. No special surface preparation is needed. Data can be obtained from fresh fracture surfeces, cut and polished surfaces, or natural surfeces. It is also possible to investigate growth zones and phase separated regions if these occur at a scale larger than the 1-2 pm optical focus limitation. 

As indicated earlier, heavy contamination can be buried, sealed or removed. Burying of the material should be well below the root growth zone, and this is normally taken as 3.0 m below the final ground-surface level. Sealing for heavy contamination to prevent vertical or lateral leaching through groundwater flow can be with compacted clay or proprietary plastic membranes. Removal from site of the contaminants is normally only contemplated in a landscaped scheme where the material, even at depth, could be a hazard to public health directly or phytotoxic to plant life. 

Contaminated groundwater (leachate) should be kept below the root growth zone. Only rainwater or clean irrigation water should meet the needs of plants. 

Silk, W.K., Hsiao, T.C., Diedenhoffen, D. Matson, C. (1986). Spatial distribution of potassium, solutes, and their deposition rates in the growth zone of the primary corn root. Plant Physiology, 82, 853-8. 

Fig. 1.15. Diagram showing the homogenization temperature of fluid inclusions vs. the iron content of the host sphalerite growth zone for sample locality NJP-X on the OH vein. The line shows the predicted iron content of the sphalerite if the sulfur fugacity of the system had been buffered by the triple point — Fe-chlorite (daphnite), pyrite, hematite (Hayba et al., 1985).

Further advances in the interpretation of mineral data could come from in situ analyses (unfortunately only possible presently on U-Th rich accessory minerals like zircon), or from detailed studies of particularly large phenocrysts, whose successive growth zones could be sampled (e g., through microdrillings) and analyzed. Ra measurements in such crystals could allow a direct determination of their growth rates. A systematic study of successive, well-dated eruptions of a given volcano, combining U-series measurements in both whole rocks and minerals, should also help with the interpretation of mineral data. 

Dashek WV, Rosen WG. Electron microscopical localization of chemical components in the growth zone of Lilium pollen tubes. Protoplasma 1966 61 191-204. 

The selected study area inFranklin County, Ohio, encompasses the city of Columbus as well as the city s suburban growth zone. We utilized Franklin County Tax Assessor data, updated in October 2000, as our database for analysis. The Franklin County Tax Assessor database contains 378,092 records, each representing a tax-lot within Franklin County. Of these 378,092 records, 79,894 were suitable for analysis. Many records had to be eliminated because of missing values in essential data fields number of stories, lot square feet, house square feet, year built, or street address. 

Cathodoluminescence images from the GB deposit show primary quartz of Type II veins (blue CL), with visible growth zoning in CL. These are crosscut by later hydrothermal Type III vein quartz that exhibits growth textures in short-lived blue and red CL colors. Both Type-ll and -III veins are weakly to moderately brecciated and are overprinted by later fluids that modified the primary quartz to red and/or yellow hydrothermal quartz characteristic of higher temperature and likely reflects... 

Hauri et al. (2002). The latter authors have shown 8 C variations of about 10%o and more than 20%c in which are associated with cathodolnminescence-imaged growth zones. Although the origin of these large variations is still unclear, they point to complex growth histories of diamonds. 

Figure 5-24 A BSE image of zircon showing a core and many growth zones. The height of the image is 240 gm. Courtesy of Charles W. Car-rigan.

Jiang J. and Lasaga A.C. (1990) The effect of post-growth thermal events on growth-zoned garnet implications for metamorphic P-T history calculations. Contrib. Mineral. Petrol. 105, 454-459. 

Crystals of platinum ditelluride can be grown when charges of platinum, sulfur, phosphorus, and tellurium in the molar ratio of 1 3 1 2 are held at 875° and the growth zone is cooled to 690°. In the preparation of both the sulfide and the telluride, adding chlorine to a pressure of 75-100 torr enhances the transport, but its presence is not essential. However, the presence of both phosphorus and sulfur is necessary. 

Coalescence Growth Mechanism. Following the very early step of the growth represented by Eq. (1), many nuclei exist in the growth zone. Hence Eq. (2) would be a major step for the crystal growth. Since there are many nuclei and embryos with various sizes in the zone, Uy in Eq. (2) can be assumed to be a random variable. Due to mathematical statistics, the fraction of volume approaches a Gaussian after many coalescence steps (3). A lognormal distribution function is defined by... 

Calcium ions are essential for building cell walls. Once absorbed by the plant, calcium ions are relatively immobile that is, they do not travel well from one part of the plant to another. The plant therefore is not so capable of reallocating calcium supplies in times of need. This is why new-growth zones, such as the tips of roots and stems, are most susceptible to calcium deficiencies. The results are twisted and deformed growth patterns. 

Cooling rate, growth zone 10°C./hour 10°C./hour... 

---