High temperature rock mass

SUPERCRITICAL WATER/ROCK INTERACTIONS AND GENERATION OF ARTIFICIAL GEOTHERMAL RESERVOIRS IN DEEP-SEATED HIGH TEMPERATURE ROCK MASSES... 

There are two principal sources of reliable partitioning data for any trace element glassy volcanic rocks and high temperature experiments. For the reasons outlined above, both sources rely on analytical techniques with high spatial resolution. Typically these are microbeam techniques, such as electron-microprobe (EMPA), laser ablation ICP-MS, ion-microprobe secondary ion mass spectrometry (SIMS) or proton-induced X-ray emission (PIXE). 

As for the determination of argon, since argon is a gas, it is extracted from rock by fusing the sample at a very high temperature (over 1600°C) and then, using a mass spectrometer, measuring the amount of gas released (Layer et al. 1987). 

The mineral corundum provides a good example. Corundum is an extremely hard substance. Small bits of corundum are part of the rock called emery which has been used since ancient times as an abrasive, to cut and grind metal and stone. Pure corundum is still used for this purpose today. Another property of corundum is that it remains solid and stable at very high temperatures, well past the melting point of iron. Therefore, masses of small corundum crystals pressed together are shaped into alumina firebricks, crucibles, and other apparatus to use in furnaces. Corundum is also the basis of several gemstones. 

Many of these reactions are in the direction needed to close the marine mass balances for major ions (Fig. 2.4). The exceptions are that they supply an unnecessary additional siiik for SO4 (CaSO precipitation) and a vast additional source of K+. The additional sink for SO4 does little damage to the marine SO4 mass balance in Fig. 2.4 because its removal affects ordy Ca + and only at the level of about 15% of the Ca + riverine inflow. The hydrothermal source for K+ cannot be rationalized as easily, because there is no adequate sink in the marine environment. Research into the sources and sinks of alkali metals reveals that K+ (and other alkali metals) that are released from basalts at high temperature are reincorporated back into basaltic rock on the sea floor at low temperature. Thus, is recycled in the vicinity of hydrothermal vents. The rates of release and incorporation are uncertain enough to obscure whether the net K+ flux is into or from the ocean in these regions. It is possible that the low-temperature removal of K+ to basalt represents a net sink large enough to accommodate the river inflow. 

Even though the experimental results are still limited, it appears that the predicted occurrence conditions provide the general trend compatible with the experimental results. Thus, it may be possible to examine the fracture process to be expected for hydraulic stimulation in supercritical rock masses on the basis of the fracture mechanism map given in Fig. 4. The ratio of the minimum horizontal tectonic stress to the vertical tectonic stress usually falls in the range of 0.5-1.0 for brittle rock masses (Brace Kohlstedt, 1980.). The actual difference of the tectonic stresses may be significantly smaller in supercritical rock masses due to the high temperature creep deformation (Fournier, 1999 Muraoka et al., 20()0). If we limit... 

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