Rock type characterization

Sedimentary rocks are highly important for hydrocarbon exploration most commercial reservoirs occur in this rock type characterized by its porosity and permeabihty. Sedimentary rocks cover more than 50% of the earth s surface and are therefore also of fundamental importance in many aspects of our lives, from agriculture to the foundations of buildings, and from groundwater resources to the whole environment. 

The results from VIRS analyses are amenable to several methods of interpretation. In the simplest sense, the spectra can be used as empirical measurements on given rock types or formations, without specific reference to the causative minerals. We have found that superficially identical rock types with different geological contexts can in some cases be effectively characterized and discriminated. The comparison of measured spectra with reference spectra from minerals is the main tool used for identification, and is very effective in cases where samples are monomineralic or dominated by a single infrared active species. The size of the area analyzed is 1 cm in diameter. Computer programs with variable levels of automation can speed the process of identification, but... 

Supergroup. The principal rock-types in the intrusion are syenites, granites and gabbros, and associated pegmatitic bodies hosting rare metal mineralization. Five distinct zones of rare metal mineralization have been identified as potentially economic. The Lake Zone is one of them and is characterized by its enrichment in the more valuable HREE (Eu, Tb, and Dy), relative to light rare earths (LREE, i.e.. La and Ce) (Palmer Broad 2007). 

During the summer of 2006, 200 petrographic and lithogeochemical samples were collected from the rocks that host the Boomerang massive sulfide deposit. In order to characterize the different rock types sampled ICP-AES and XRF analysis of these samples was completed by ALS Chemex (Sudbury Ontario), and Memorial University of Newfoundland, respectively. 

Five different vein phases (Types i to V) are recognized at both deposits, aii have variabie amounts of carbonates and quartz gangue. Type i veins contain oniy brecciated quartz and carbonate minerals and at ED are spatially associated with disseminated arsenopyrite, chalcopyrite, pyrrhotite, and pyrite in the mafic host rock. Type II veins in both deposits are partly brecciated and contain 5-80% sulfides of dominantly pyrite, arsenopyrite, and at GB chalcopyrite. Type III veins are quartz-calcite-tetrahedrite-bismuthinite microveins that cut both Types I and II veins. The fine-grained sulfides replace and enclose arsenopyrite and pyrite in Type II veins and are also visible in microfractures within the Type II sulfides. Type IV veins are base-metal rich and characterized by galena, sphalerite, chalcopyrite, pyrite, and stibnite with a maximum width of 20 cm. The Type V veins are late barren-carbonate veins cutting all previous veins and textural features. 

Characterization of the natural setting is usually a major portion of the field investigation. At most sites, permeability of the local soil and rock types, the depth of the water table, and the direction of groundwater flow will strongly influence movement of contaminants from the point of disposal. The anomalies which occur naturally within the geohydrologic section must be taken into consideration. Surface drainage, sewers, and buried utilities can affect surface and groundwater flow around a hazardous waste site. 

A geographic region that is characterized by a rock type or a suite of rock types that have a common origin (e.g., glacial terrain). 

Expert System for the Characterization of Rock Types (ESCORT) is an expert system based on Bayesian rules providing probabilities for the occurrence of rock types based on geochemical and nongeochemical data. 

We have emphasized that the modelling and the associated rock mass characterization should be determined by the rock engineering objective. This means that different types of information will be required for THMC modelling for the different types of application, as illustrated by the themes of this conference and the associated papers. However, site investigation has limited methods of approach, e.g. surface outcrop studies, borehole and borehole core measurements, and geophysics, which means that we will not have as much information as we would like and concessions have to be made on both the site investigation and modelling sides. 

The rocks of the Dufek intrusion have a wide range of densities which correlate positively with the abundance of pyroxene. This relationship in Fig. 13.44 was worked out by Ford and Nelson (1972, Fig. 1) who measured the densities of approximately 600 rock samples of the Dufek intrusion. The results indicate that the different rock types can be characterized by their densities in grams per cubic centimeters ... 

Fig. 23. Lanthanide abundance patterns for Mid-Ocean Ridge Basalts (MORE) and Ocean-Island Basalts (OIB) (data are from table 16). Note the depletion in the light lanthanides (La-Sm) in MORE derived from a depleted mtmtle source, and the enriehment of light lanthanides in OIB. Nd isotopic evidence indicates that the source of both these rock types was characterized by long term depletion of Nd relative to Sm, indicating the observed light lanthanide enrichment in OIB is a recent event.

As there is a wide spectrum of landslide types, the potential or already occurred landslides should be classifled as clear as feasible. The criteria used by the UNESCO Working Party on World Landslide Inventory in classiflcation of landslides follow Varnes (1978) in emphasizing the type of movement and type of material. The divisions of materials are rock, debris, and earth. Rock is characterized as an intact hard or Arm mass in its natural place prior to the initial movement, whereas soil is referred to as an aggregate of unconsolidated solid particles, either transported or derived in place via the weathering processes. The latter is further divided into earth, in which 80% or more of the particles are smaller than 2 mm in size, and dehris, whereby 20%-80% of the solid particles are larger than 2 mm. 

For safety reasons, it was not possible to take actual field samples for laboratory analysis to correlate with the specific ReLIBS samples. Thus the spectral types based on different emission lines relative intensities as an indicator of the rock types were determined. In order to do this, the spectra of the well characterized rock samples, were measured in laboratory conditions. Based on calibration curves... 

Although the choice of method is often dependent on the rock type, a combination of several extraction and characterization techniques may frequently be used to provide data that aid understanding of hydrogeological features, particularly when pore-water compositions can be compared with groundwater data. 

Figure 8.13 shows the results with a separation of the three carbonate rock types. The vuggy Wetterstein dolomite is characterized by high formation factors. In a forthcoming paper (MiiUer-Huber et al., 2015), a comparison with model calculations demonstrates the effect of pore geometry, expressed by the ratio of pore-body and pore-throat radius (see Section 8.4.5). 

Sedimentary rocks are characterized by a broad scatter of thermal properties within a single lithological type. This is originated mainly by the complex influence of mineral composition, texture and grain cementation, porosity, and pore fluids (Table 9.7). 

Oceanic crustal rocks are characterized by positive values (0 to + 10). In marked contrast, the continental crust has negative values (-10 to -30). Hence, the weathering of different rock types delivers Nd, in dissolved and particulate river matter, with regionally distinct isotopic compositions (Goldstein and Jacobsen 1987, 1988b). Rivers... 

Bismuth(V) oxide and bismuthates are even less well established though a recent important development has been the synthesis and structural characterization of LisBiOs, prepared by heating an intimate mixture of Li20 and Q -Bi203 at 650° for 24 h in dry O2. The structure is of the defect rock-salt type with an ordering of... 

The heavier metal tantalum is distinctly less inclined than niobium to form oxides in lower oxidation states. The rutile phase TaOz is known but has not been studied, and a cubic rock-salt-type phase TaO with a narrow homogeneity range has also been reported but not yet fully characterized. TazOs has two well-established polymorphs which have a reversible transition temperature at 1355°C but the detailed structure of these phases is too complex to be discussed here. 

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