Rock Environment

Coal geology is a branch within the field of geology which is focused on coal, which is an abundant fossil fuel with a number of uses. 

The study of coal geology includes a wide variety of topics, including coal formation, occurrence, and properties. Coal formation is of great interest because the process of formation can determine the geological composition of the coal, which in turn determines how coal can be used. Knowledge of coal formation can help geologists find new coal deposits and determine the extent and value of existing deposits. 

Cycads are seed plants characterized by a large crown of compound leaves and a trunk. They are evergreen and have large pinnately (feather-Uke or multi-divided features arising from both sides of a common axis in plant) compound leaves. They are frequently confused with and mistaken for palms or ferns, but are only distantly related to both. 

Coal formation began during the Carboniferous Period (known as the first coal age), which spanned 360 to 290 million years before present. The Carboniferous Period is divided into two parts. The Lower Carboniferous, also called the Mississippian, began approximately 360 million years ago and ended 310 million years ago. The Upper Carboniferous, or Pennsylvanian, extended from about 310 to 290 million years ago, the beginning of the Permian Period. 

Coal formation continued throughout the Permian, Triassic, Jurassic, Cretaceous, and Tertiary Periods (known collectively as the second coal age), which spanned 290 to 1.6 million years before present. During that time, coal formation started from thick layers of dead plants that piled up in ancient swamps. The dead plant layers were buried deeper and deeper under even thicker layers of sand and mud. During burial, pressure and heat changed the plant material into coal. Coal from the western United States usually formed during or after the era of the dinosaurs (about 50-100 million years ago). 

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Ma Q.Y., Logan T.J., Traina S.J. Lead immobilization from aqueous solutions and contaminated soils using phosphate rocks. Environ Sci Technol 1995 29 1118-1126. 

Goff, F. and Lackner, K.S., Carbon dioxide sequestering using ultramafic rocks, Environ. Geosci., 5(3), 89,1998. 

Other models considering the same variables but different equilibria may be considered. Empirical data outlining the phases present in a specific environment will lend support to a particular model as being valid. The solids chosen here are commonly found in the sedimentary rock environment, both ancient and recent. 

Kinniburgh, D. G., and Miles, D. L. (1983). Extraction and chemical analysis of interstitial water from soils and rocks. Environ. Sci. Technol. 17(6), 362-368. 

A continuum of subterranean environments exists, ranging from very hard rocks such as granites and basalts, through sedimentary rocks and sandstones, to as yet unconsolidated, fairly soft sediments. Two main subterranean rock environments can be defined hard rocks - those too hard and impermeable to allow microbes to pass, except via fractures, and... 

Table 1 Chemistry and mineralogy of representative rock t)fpes from crystalline rock environments (analyses normalized to 100%, including MnO, P2O5, water free oxides are in wt.%).

The data in Table 2 are from groundwaters found in a variety of crystalline rock environments on several different continents. The ages and size of the rock complexes vary. The oldest are billions of years, the youngest tens of millions. Some are individual plutons or batholiths others are massive complexes composed of many rock types of variable age. To attempt to subdivide the data based on crystalline rock type, size of rock complex or rock age would result in so many subdivisions that any discussion of origin and evolution would be unnecessarily cumbersome. 

In the next section, the data from Table 2 are combined with a much larger database of chemical and isotopic analyses taken from numerous published documents (e.g., Blomqvist, 1999) and data previously unpublished by two of the authors (Frape and Blomqvist). The following figures and text are designed as a brief summary of the geochemical and isotopic distribution and trends found in groundwaters from a number of crystalline rock environments. 

Figure 2 Stable isotopic composition for groundwaters from crystalline rock environments (a) coded for...

The most noticeable isotopic difference between saline waters from crystalline rocks and sedimentary formation waters is their position above the meteoric waterline. This is postulated to be due to mineral hydration reactions in a very water-depleted environment (Fritz and Frape, 1982). Several recent smdies have suggested that hydration reactions in low water to rock environments can occur and result in increasing salinity. The incorporation of OH into primary silicate such as amphiboles and phyUosUicates (where OH crystal lattice sites are part of the mineral structure) is suggested as one mechanism for controlling solute concentration (KuUemd, 2000). The formation of secondary OH containing mineral phases such as zeolites and clays can also continue to consume water molecules and concentrate the residual fluids both chemically... 

Many authors have proposed that the rock environment, through a series of chemical reactions, will extensively modify fluids in contact with it (Chebotarev, 1955 Collins, 1975 Edmunds et al., 1984, 1987). Early research in this area suggested that long-term evolution of subsurface saline fluids favored the formation of calcium chloride brines that are very old. However, the origin of these brines could not be determined (Krotova, 1958 Rittenhouse, 1967). 

Numerous secondary mineral-fluid reactions have been shown to occur in crystalline rock environments (Bucher and Stober, 2000). As mentioned previously, reactions in ultramaflc and maflc rocks can have considerable control on pH, carbonate precipitation, and most likely the accumulation of excess H2 gas (Barnes and O Neil, 1971 Sherwood Lollar et al., 1993b). A typical reaction (Equation (1)) (not balanced) that would involve olivine dissolution (Drever, 1988) and in closed systems would also consume water and concentrate solutes is as follows ... 

Continental-scale hydrologic forces can control the flow of basinal brines and are another major potential external source of saline fluids that may enter crystalline rock environments. Studies by Bottomley et al. (1999) suggest that hydraulic gradients in northwestern Alberta are such that brines are forced from Devonian strata into the underlying Canadian Shield. Similarly, it appears that western Canadian sedimentary basin brines have entered the Canadian Shield in some parts of the Lac du Bonnet batholith, Manitoba (Gascoyne et al., 1987). 

A wide range of groundwater chemistry has been recorded in crystalline rock environments. Shallow groundwaters (usually <200 m) are dominantly Ca-Na-HCOa formed by the interaction of atmospherically recharged meteoric water with the soil and shallow bedrock. These waters are fresh with dilute dissolved loads and young, as indicated by the presence of tritium. Occasionally, saline intrusions from adjacent seawater bodies or upwelhng of deeper saline fluids can influence the chemistry of shallow groundwaters. 

The debate on the origin and evolution of the fluids in crystalline rocks is very much an ongoing research area. A number of experimental and research sites such as the ones discussed in this chapter will continue to produce hydrogeochem-ical information well into the middle of this century as researchers around the globe attempt to understand the hydrogeology and geochemistry of crystalline rock environments. 

An increase in pressure always leads to an increase in the solubility of minerals. Why In what natural water-rock environments is the effect of pressure on important ... 

Whether apatite represents the tail or the dog in halogen mass balance during metamorphism most likely depends on the environment. In high fluid/rock environments where fluid composition controls rock composition (e.g., veins, skams and ore deposits). 

This section deals with the comparison of MOTIF modelling results with three field experiments and a large bench-scale experiment. While the inherent experimental uncertainties in fractured rock environments are such that an absolute validation is difficult to achieve, the comparison provides some confidence in the suitability of the code to model various subsurface processes in fractured or porous rock. 

Because of the long half-lives of these nuclides they must have been formed at the time of (or possibly even before) the formation of the solar system and of the earth. When the earth s crust solidified, these radionuclides became trtq[>ped in rocks. As they decayed, decay products accumulated in the closed rock environment. By measuring the amount of parent and daughter nuclides, it is possible with the half-life to calculate how long this environment (e.g. a rock formation) has existed. This is the bases for nuclear dating (also called "radioactive clocks ), and almost all of the nuclides in Table 5.2 can be used for this purpose. In 5.8 we discuss dating methods for the K—Ar and Rb—Sr systems. 

The source bed concept postulates that all coal seams are derived from plant material that was deposited syngeneticaUy at one particular horizon of the sedimentary basin constituting the field, and that changes to the plant material changed (evolved) to coal in varying degrees under the influence of rise in temperature and pressure of the rock environment. 

The influence of petrophysical properties on the salt weathering of porous building rocks. Environ. Geol. 2007,52(2) 197-206. 

The proposed solution to manage HLW is the development of a Geological Disposal Facility (GDF) where HLW is placed in a deep rock environment which is stable and unaffected by environmental change for hundred thousands of years. Under this condition radioactive waste which is protected from underground water by a geological, concrete and metallic barrier undertakes a natural process of radiation reduction called radioactive decay (NDA 2010). 

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