Clayey rocks

Properties of clays and clayey rocks, and also the processes in them depend on a number of factors. Then the mathematical simulation of the properties and processes, as one of the methods of their examination, is a rather difficult problem. Physically it is clear that the speciflc properties of clay rocks (low permeability, plasticity in moist condition) are caused by the existence of clay minerals in their composition, and these properties are a manifestation of surface capacities, which exist between particles of the clay minerals, which are included in the composition of clays. The most useful conception of the activity of surface capacities is the conception of disjoining pressure between colloid particles, Mitchell (1976). In this work we provide a description of the physical and mechanical clay properties and transport processes in them. The description is based on methods of theory of filtration consolidation. Nikolaevskiy (1996), and also on the theory of stability of lyophobic colloids (theory of Deijaguin-Landau-Verwey-Overbeeck, or DLVO theory), which uses the conception of disjoining pressure. 

Khramchenkov, M.G. 2000. Mathematical simulation of clayey rock s transport and storage properties. Environmental Geoscience 4 pp. 401 - 405 (in Russian). 

CHARACTERIZING IN THE LABORATORY PERMEABILITY CHANGES INDUCED BY DEVIATORIC STRESS IN CLAYEY ROCKS... 

Bornert, M, Vales, F, Gharbi, H., Minh, D.N. 2010. Multiscale full-field strain measurements for micro-mechanical investigations of the hydromechanical behaviour of clayey rocks. Strain 46(1) 33-46. 

In Uruguay, vertisols are widespread soils that are basaltic, silty clayey rock and loess weathered products. In the south, Quaternary clayey and silty clayey sediments as Libertad Fm. cover Precambrian (igneous and metamorphic) rocks, sedimentary rocks and Cenozoic sediments. Clayey soils developed in Libertad Fm. are very often found and when clay dominant there are smectite (Musso 2001). These soils have more than 90 % of silt and clay, low and medium Atterberg limits and its bearing capacity of foundation is from 100 to 200 kPa (Departmento Geotecnica 1997). 

In vertisols on diorite, basalt, alluvions, and dolerite, total Mn is in the range of 1250-2750 mg/kg, while brown isohumic soils on calcareous sandstone and clayey sediments contain 550-1670 mg/kg Mn. Soils in the Adelaide and Southeast regions contain 140-1400 mg/kg total Mn. In solods on granitic rocks and alluvions, total Mn is 60-990 mg/kg. 

Meade (1966) shows that claystones have a porosity decreasing to 0% at 1 Km depths and sandstones, 20% porosity at the same depth. Manheim (1970) shows that ionic diffusion rates in sediments are 1/2 to 1/20 that of free solutions when the sediments have porosities between 100 - 20%. It is evident that the burial of sediments creates a very different physical environment than that of sedimentation. As a result of reduced ionic mobility in the solutions, a different set of silicate-solution equilibria will most certainly come into effect with the onset of burial. The activity of ions in solution will become more dependent upon the chemistry of the silicates as porosity decreases and the system will change from one of perfectly mobile components in the open sea to one approaching a "closed" type where ionic activity in solution is entirely dictated by the mass of the material present in the sediment-fluid system. Although this description is probably not entirely valid even in rocks with measured zero porosity, for practical purposes, the pelitic or clayey sediments must certainly rapidly approach the situation of a closed system upon burial. 

Abrasive coasts are mostly composed of clayey deposits, poorly-cemented rocks, or limestones. The cliff heights range from 15 to 35 m. The abrasion rate is controlled by the composition of the coastal rocks and the cliff heights. The recession of the cliffs is also caused by the development of landslide and caving processes, especially under the conditions of strong storms. The length of individual sliding blocks reaches 500 m at a width of up to 15 m. Deep surf niches are formed in the lower parts of the cliffs. 

In Table 3, susceptibility to weathering increases down the list as fewer silicon-oxygen bonds need to be broken to release silicate. Consequently, quartz and feldspars especially, but also mica in temperate soils, are common inherited minerals in the coarse particle size fractions of soil (the silt and sand fractions, 0.002-2 mm). The amphiboles, pyroxenes, and olivine are much more easily weathered. Thus, soils derived from parent material with rock containing a predominance of framework silicates e.g. granite, sandstone) tend to be more sandy, while those derived from rocks containing the more easily weathered minerals tend to be more clayey. 

Precambrian paleosols reviewed by Rye and Holland (1998), these paleosols reveal the antiquity and thoroughness of hydrolytic weathering during the Precambrian. Even then, rock and sediment were under relentless acid attack, which leached base cations (especially Ca " ", Mg " ", and Na ), and left thick, clayey soil. 

Bentonite. A soft, porous, moisture-absorbing rock composed essentially of clayey minerals, in particular, montmorillonite, in the form of extremely small erystals. 

Figure 8.1 defines the different types of subsurface-waters. The zone above the water table is called the zone of aeration, vadose zone, or unsaturated zone. Moving downward in this zone we encounter first soil water or soil moisture, then intermediate vadose water, and then capillary water. Capillary water rises into rock and sediment pores above the water table because of capillary forces. The capillary zone may be as much as 30 ft (9 m) thick in clayey sediments. To the extent the unsaturated zone can truly be called the zone of aeration, then air and atmospheric oxygen are present and conditions are oxidizing. 

Assume it is necessary to place a 100 long cut-off (grout curtain) through a 20 foot depth of granular materials, overlain by 5 feet of clayey silt and underlain by rock. 

Genetically, the Aralian coasts may be classified into three types, namely, abrasion coasts (modeled by marine erosion), depositional and abrasion-deposition-al ones [25]. Coasts of the first type (abrasion) are most common at the western, northern and part of the southern margins of the sea. They are built of compact calcareous marls and sandy-clayey Paleogene and Neogene rocks. Typically, they form high (up to 200 m) abrasion cliffs with wave-cut notches and a narrow strip of sandy beach. In areas where loose rocks occur, coasts are rather low, with a shallow notch and broader beach. There exist varieties of abrasion coasts, such as abrasion-denudation ones and abrasion coasts with slumps, with material from screes, rockfalls, and slumps present in the nearshore zone in abundance. 

Outside the direct influence zone of the ore deposits, regional glaeial till material often forms the basis on which soils develop. The soil profile described here in detail, comprises five horizons (H-C) and is more than 2 m thick (Fig. 11D). The E-horizon is only weakly bleached, as typical for cryptopodzols. The C-horizon is very clayey and corresponds to the regional till cover mentioned above. The soil percolation water profile shown in Fig. 1 ID was sampled at a distance of 200 m, where the whole profile was less deep and evolved. It has the same major and traee element composition, but shows soil pH values between 4 and 6, instead of 6.5 to almost 8, as in the profile shown in Fig. IID. This higher soil pH seems to be due to the slight influence of nearby outcropping amphibolitic rocks of basaltic composition (Fig. 11 A). 

In summary, due to a relatively large proportion of externally derived material in soil, the trace element concentrations in the soil of the Swiss Jura are only partially representative for limestone-dominated systems. Nevertheless, many soils of the Jura mountains are rich in Cd of natural origin. It was demonstrated that this Cd derives from calcite dissolution and not from weathering of the insoluble clayey fraction of the rock. Moreover, unexpectedly high amounts of radon are released in this region. 

This trend appears to be confirmed by the analysis of the samples reliably associated with the different lithologies (Table 1). Indeed, roes harvested on clayey terrains have the highest median value, while those shot on limestones and heterogeneous flysches have the lowest ones. High values, even though referring to only three samples, come from roe deer which lived on mafic magmatic rocks. 

As was seen for zinc, the background lithology seems to influence the copper levels in roe deer blood, albeit to a much smaller extent. The highest median value (0.76 p-g/ ml) was found in roes which lived on clayey terrains, in which copper is normally the most enriched among the chalcophile elements (Faure, 1991). Likewise, the values for the (unfortunately very few) roes that lived on mafic magmatic rocks seem to be relatively high. 

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