Crystalline rocks

Marble is a metamorphic, highly crystalline rock that may be high calcium or dolomitic limestone of varying purity. It occurs in virtually every color in diverse motded effects and is the most beautiful form of limestone. It is usually very hard and can be cut and poHshed to a very smooth surface. 

Petit J-C, Langevin Y, Dran J-C (1985a) Radiation-enhanced release of uranium from accessory minerals in crystalline rocks. Geochim Cosmochim Acta 49 871-876 Petit J-C, Langevin Y, Dran J-C (1985b) " U/ U disequilibrium in natnre theoretical reassessment of the varions proposed models. Brill Mineral 108 745-753... 

In Africa, Precambrian crystalline rocks are exposed over about one quarter to one third of the arid/semi-arid land surfaces (Dregne, 1976). While mountain chains are located in the northwest, east and south, much of the rest of the arid and semi-arid land consists of sandstone, limestone, loose... 

The extent to which molecular diffusion affects dating of fractured rock has yet to be evaluated thoroughly with proper models. Although diffusion is a slow process in dense crystalline rocks, it could still have an important influence on dates of very old groundwater. With atmospherically derived radionuclides, dates of water affected by this slow diffusion should appear too old. On the other hand, dating of water based on the accumulation of helium which diffuses out of solid rock into... 

In light of the small solubilities of many minerals, the extent of reaction predicted by this type of calculation may be smaller than expected. Considerable amounts of diagenetic cements are commonly observed, for example, in sedimentary rocks, and crystalline rocks can be highly altered by weathering or hydrothermal fluids. A titration model may predict that the proper cements or alteration products form, but explaining the quantities of these minerals observed in nature will probably require that the rock react repeatedly as its pore fluid is replaced. Local equilibrium models of this nature are described later in this section. 

Precambian crystalline rocks (Uzanda) Cenozoic volcanic rocks (Tanzania) ... 

In weakly consolidated, stratified sediments, the injection pressure must be controlled so that the surrounding formation is not fractured. If fracturing occurs, there is usually a severe loss in hydraulic conductivity because the bedding planes are disturbed. Pressures that will cause fracturing range from a low of 0.5 psi/ft of depth for poorly consolidated coastal plain sediments, to 1.2 psi/ft depth for crystalline rock. For most recharge wells in unconsolidated sediments, the injection pressure should be carefully controlled so that the positive head (in psi at the surface) does not exceed 0.2 x h, where h is the depth (in ft) from the ground surface to the top of the screen or filter pack. 

Fig. 5.18 illustrates the difference in water chemistry of rivers draining CaC03 (cal-cite) or crystalline rocks. 

Case Study Chemical Weathering of Crystalline Rocks... 

Case Study Chemical Weathering of Crystalline Rocks in the Catchment Area of Acidic Ticino Lakes, Switzerland... 

Giovanoli, R., J. L. Schnoor, L. Sigg, W. Stumm, and J. Zobrist (1989), "Chemical Weathering of Crystalline Rocks in the Catchment Area of Acidic Ticino Lakes, Switzerland," Clays Clay Min. 36, 521-529. 

Kaufmaim RS (1989) Equilibrium exchange models for chlorine stable isotope fractionation in high temperature environments. In Proc 6 Int S>mp Water-Rock Interaction. Miles DL (ed) p 365-368 Kaufmann RS, Frape SK, Fritz P, Bentley H (1987) Chlorine stable isotope composition of Canadian Shield brines. In Saline Water and Gases in Crystalline Rocks, Fritz P, Frq)e SK (eds) Geological Association of Canada Special Paper 33 89-93... 

Somewhat unusual isotopic compositions have been observed in highly saline deep waters from Precambrian crystalline rocks as well as in deep drill holes, which plot above or to the left of the Meteoric Water Line (Frape et al. 1984 Kelly et al. 1986 Frape and Fritz 1987). There are two major theories about the origin of these Ca-rich brines ... 

B) The brines are produced by leaching of saline fluid inclusions in crystalline rocks or by intense water/rock interactions (Frape and Fritz 1987)... 

Frape SK, Fritz P (1987) Geochemical trends from groundwaters from the Canadian Shield, In P, Fritz, SK Frape (eds,) Saline water and gases in crystalline rocks, Geol Ass Canada Spec Paper 33 19-38... 

Battelle Pacific Northwest Laboratory Researchers discovered microbial communities in deep crystalline rock aquifers within the Columbia River Basalt (CRB) Group at a U.S. Department of Energy site in Hanford, Washington. While most subsurface microbial communities depend upon photosynthesis for energy (directly or indirectly), SLiME was found to derive energy from hydrogen that comes from reactions between water and basalt. SLiME could potentially be used in deep strata because they are preadapted to these conditions. 

Studies of the sorption of natural radionuclides from groundwater have established that minor minerals, such as clays coating the fractures in crystalline rock and Fe- and Mn-oxyhydroxides, are important sinks for radionuclides. For example, investigations carried out at the Aspo facility (Smellie Karlsson 1999) showed qualitatively that rare earth elements (REEs), Sc, Th, U, Ra, and Ba have been scavenged by Fe-oxyhydroxide and calcite precipitates,... 

Landstrom, 0., Klockars, C.-E., Holmberg, K.-E. and Westerberg, S., "In Situ Experiments on Nuclide Migration in Fractured Crystalline Rocks", KBS TR 110, 1978... 

Apps, J. A., Cook, N.G. W. and Witherspoon, P. A., "An Appraisal of Underground Radioactive Waste Disposal in Argillaceous and Crystalline Rocks Some Geochemical, Geomechanical and Hydrogeological Questions", LBL-7047, UC-70, Lawrence Berkeley Laboratory, Berkeley 1978... 

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