Rock-mass

In combination, carbon is found as carbon dioxide in the atmosphere of the earth and dissolved in all natural waters. It is a component of great rock masses in the form of carbonates of calcium (limestone), magnesium, and iron. Coal, petroleum, and natural gas are chiefly hydrocarbons. 

Deposits which are forming are frequentiy characterized by venting streams of hot (300°C) mineralized fluid known as smokers. These result in the local formation of metalliferous mud, rock chimneys, or mounds rich in sulfides. In the upper fractured zone or deep in the rock mass beneath the vents, vein or massive sulfide deposits may be formed by the ckculating fluids and preserved as the cmstal plates move across the oceans. These off-axis deposits are potentially the most significant resources of hydrothermal deposits, even though none has yet been located. 

Metamorphic rocks are formed from either igneous, sedimentary, or possibly other metamorphic rock masses. These original rock masses are subjected to heat. 

Fig. 2.47. Model predicting mineral assemblages and proportions produced when basalt reacts with seawater in different water/rock mass ratios. The model is based on experimental data but is close to actual observed assemblages in recovered greenschist facies metabasalts (Mottl, 1983).

The relative area of mine solid waste tails (per 100,000 M3 of rock mass) is 0.7-0.8 of the total area. On average, the disturbed areas of uranium ore exploration site are partitioned as follows 32.3% of disturbed land is occupied by dumps, 27.2%, by pits, 20.3%, by industrial areas, 13.3%, by tails, and about 10%, by other types of land disturbance. 

The most common, and certainly the most familiar, inorganic fibers are the mineral fibers known as asbestos. Several minerals have been mined as asbestos (Fig. 1.1 A, C see chapter 2 for a detailed discussion of the asbestos minerals). These minerals are widespread in nature, but mining is economical only when they occur as continuous fibrous aggregates (veins) crosscutting rock masses. The veins are made up of hairlike fibers in parallel array that, on close inspection, appear bent (Fig. I.IB). Not surprisingly, a mineralogical term, asbestiform, has been used to describe this subset of inorganic materials. 

Silicate minerals that usually occur as spherulitic aggregates of fibers have formed as a result of the alteration of the many minerals subsumed within the category of biopyriboles. Alteration of the micas under hydrothermal conditions produces compositional variants on recrystallization such as hydrous muscovite. Some of these samples have been labeled asbestiform, probably because they are found in veins that criss-cross rock masses. Fibrous micaceous minerals also occur as discrete disseminated particles, although few detailed analyses of crystallites from the disperse occurrences have been made. Fibrous mica found in veins usually grades (composition-ally) into members of the serpentine mineral group, the clays or the chlorites. 

As must be obvious, we have only touched on the natural occurrences of crystalline fibrous Si02- For example, Si02, usually quartz, often replaces fibrous minerals of another composition as rock masses are altered. Si02 also occurs in fibrous form within some plants (phytoliths) and in the soil. To summarize, in addition to the usual and common occurrences of the mineral quartz and its varieties, several silica polymorphs occur as fibers in a variety of biologic and geologic environments. 

Temperature was set at 35 °C. Brine-rock mass ratio was set to 0.4 10, which corresponds to a porosity of approximately 10%. The mineral content and brine compositions were set to measured values (Table 1). Debyc-Hiickel equations were used to correct activity coefficients for saline solutions. The brine was allowed to come to equilibrium with the C02, then the 10 kg of sandstone was added and equilibrium assemblages were computed a second time. 

Bruel, D. 1995. Heat extraction modeling from forced fluid flow through stimulated fractures rock masses Applications to the Rosemanowes hot-dry rock reservoir. Geothermics, 24, 361-374. 

Tunnels are subsurface constructions to overcome topographic barriers to transportation. They can serve various purposes (highway, railway, pipelines). Depending on local geologic conditions the tunnels can serve, especially in mountainous terrain, as heat/fluid sources railway and road tunnels as well as major galleries drain water from their surrounding rock masses. 

The absence of such minerals as biotite, which could have formed at temperatures as low as 300°C., supports the assumption of a lower maximum temperature for the rock mass. Fresh chlorite, the low temperature analogue of biotite, is abundant in the slate and is unstable only at higher temperatures. In view of these things, it is proposed that the slate and the anthraxolite were heated together at great depth, to a maximum temperature between 300° and 600°C., but probably much closer to the lower value. 

When we assume that the first minerals crystallized from a magma, a liquid rock mass, then the movement of the crystals in the magma will mainly be determined by their densities. Light minerals will rise to the surface, whereas heavy ones will sink. A number of densities of elements are listed in table 7.3 which will give you some idea of the occurrence of the various elements in the different earth layers. Please bear in mind that compounds are and were formed during the transport in magma and that this can lead to drastic changes in density. 

Igneous rocks are also called solidification, eruption or magma rocks. They are formed from the solidification of magma, a liquid rock mass in which gases can also be present. When this solidification process takes place in the earth s crust, we speak of effusive or volcanic... 

The Soxhlet extractor (figure 8.4) is filled with fine grains of one of the two kinds of rock which are most common on the earth s surface, viz. basalt and granite. Next water is constantly passed through this rock mass and for a very long time. This results in a continuous extraction of materials from the rock in other words the rock is exposed to... 

When we call the rock mass through which the water perculates zone A and mass which is occasionally submerged zone B, then figure... 

Kanatani, K. 1985. Measurement of crack distribution in a rock mass from observation of its surfaces. 

CW/R = water/rock mass ratio. dDO = dissolved oxygen. 

Applications. In the following paragraphs, the conditions (temperature, time, water/rock mass ratio, surface area) and the results on closed system oxygen consumption and redox conditions of the basalt-water experiments are compared to expected conditions in the open system backfill and near-field environment of an NWRB. Crushing of basalt for pneumatically emplaced backfill could result in a substantial fraction of finegrained basalt with a variety of active surface sites for reaction similar to the crushed basalt used in the experiments. The effects of crushing on rates of mineral-fluid reactions are well documented (10,26). 

It can be seen in Table 9.7 that the particulate load constitutes by far the most important contribution (88%) of total river discharge of materials to the ocean. The amount carried as solids should be increased by bed load transport, which usually is considered to be about 10% of the total suspended load (Blatt et al 1980). The mean chemical composition of river suspended matter closely approximates that of average shale (Table 9.8). This resemblance is expected because suspended solids in rivers are derived mainly from shales. Sedimentary rocks constitute about 66% of the rocks exposed at the Earth s surface fine-grained rocks, like shales, comprise at least 65% of the sedimentary rock mass. Thus, roughly 50% of surface erosion products come from shaly rocks. 

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