Illite distribution

Some of the clays that enter the ocean are transported by river input, but the vast majority of the riverine particles are too large to travel fer and, hence, settle to the seafloor close to their point of entry on the continental margins. The most abundant clay minerals are illite, kaolinite, montmorillonite, and chlorite. Their formation, geographic source distribution and fete in the oceans is the subject of Chapter 14. In general, these minerals tend to undergo little alteration until they are deeply buried in the sediments and subject to metagenesis. 

The global distribution patterns of kaolinite, chlorite, montmorillonite, and illite in pelagic sediments are listed in Table 14.3 and illustrated in Figures 14.8 through 14.11. 

Distribution of illite (as a percentage of the four major clay minerals) in the < 2 xm noncarbonate fraction of deep-sea sediments. Source From Griffin, J. J., et al. (1968). Deep-Sea Research, 15, 433-459. 

If we now consider the bulk compositions of the mixed-layered minerals which contain both expandable and non-expandable layers, two series are apparent, one between theoretical beidellite and illite and one between theoretical montmorillonite and illite (Figure 25). The intersection of the lines joining muscovite-montmorillonite and beidellite-celadonite (i.e., expandable mineral to mica), is a point which delimits, roughly, the apparent compositional fields of the two montmorillonite-illite compositional trends for the natural mixed layered minerals (Figure 26). That is, the natural minerals appear to show a compositional distribution due to solid solutions between each one of the two montmorillonite types and the two mica types—muscovite and celadonite. There is no apparent solid solution between the two highly expandable (80% montmorillonite) beidellitic and montmorillonitic end members. The point of intersection of the theoretical substitutional series beidellite = celadonite and muscovite-montmorillonite is located at about 30-40% expandable layers— 70-60% illite. This interlayering is similar to the "mineral" allevardite as defined previously. It appears that as the expandability of the mixed... 

The mineralogical composition of Sahara dust particles shows the predominance of aluminosilicates (clays). Illite is also present in many cases while quartz particles are rare. Scanning Electron Microscopy (SEM) results on dust composition transported over different regions in the Mediterranean Basin have shown that Al-rich clay minerals such as illite and kaolinite are very common in PM10 for Cypms and dominant for Crete. Dust particles are also very rich in calcium which is distributed between calcite, dolomite and sulphates and Ca-Si particles (e.g. smectites) whereas iron oxides are often detected [43]. 

Intact soil cores (6.7 cm i.d.) were taken with spilt spoon at depths of 1 to 2 meters from a field test site located approximately 50 km east of Cincinnati, Ohio. The soil in this interval consists mainly of quartz (60%) and clay minerals (35%) with minor amounts of plagioclase and potassium feldspar. The majority of clay is illite and smectite, with minor amount of kaolinite. Soil chemical properties were analyzed prior to, and after, electroosmosis, in order to evaluate the effects of electroosmosis on the distribution of elements within the soil column. Sampled cores were wrapped in aluminum foil and stored at 12°C until the EO cell was assembled. 

Fig. 1. Histograms showing the distribution of the oxides of twenty-nine illites.

Divalent iron is considerably more abundant in glauconite than in illite and montmorillonite although the Mg content of glauconite is similar to that of mont-morillonite. Octahedral Fe3+ is five times more abundant in glauconite than in illite and montmorillonite, and octahedral A1 is less than one-third as abundant. The total number of trivalent ions in the octahedral position averages 1.45 as compared to 1.76 for montmorillonite and 1.68 for illite. The distribution of total trivalent ions in the octahedral sheet of glauconites is approximately normal (Fig.5). Reported values ranged from 1.15 to 1.89 however, as with the A1 2 1 clays, there is a deficiency of values less than 1.30. 

Diagenetic modification of expandable clay during burial is an important source of mixed-layer illite-montmorillonite. With increasing depth of burial and increasing temperature the proportion of contracted 10 A layers systematically increases. From about 50°C— 100°C the contracted layers are distributed randomly. At higher temperatures only a few additional layers are contracted but the interlayering becomes more ordered (Perry and Hower, 1970 Weaver and Beck, 1971a). The final product, 7 3 to 8 2, is relatively stable and persists until temperatures on the order of 200°C— 220° C are reached. 

The type of clay mineral, depending on its abundance and degree of K+ (or NH4+) saturation, may control the adsorption, phase distribution and thus the mobility and (bio)availabihty of NACs in soils [152], The affinity of adsorption capacity of the clays for NACs increase in the order kaolinite < illite < montmorillonite [152],... 

Beckett described inductively coupled plasma mass spectrometry (ICP-MS) as an off-line detector for FFF which could be applied to collected fractions [ 149]. This detector is so sensitive that even trace elements can be detected making it very useful for the analysis of environmental samples where the particle size distribution can be determined together with the amount of different ele-ments/pollutants, etc. in the various fractions. In case of copolymers, ICP-MS detection coupled to Th-FFF was suggested to yield the ratio of the different monomers as a function of the molar mass. In several works, the ICP-MS detector was coupled on-line to FFF [150,151]. This on-line coupling proved very useful for detecting changes in the chemical composition of mixtures, in the described case of the clay minerals kaolinite and illite as natural suspended colloidal matter. 

The other clay mineral, illite, also has some strontium sorption, but the distribution coefficient is about one order of magnitude lower than that of montmorillonite and rectorite. Since, in illite, the layer charge is compensated by non-exchangeable cations (Chapter 1, Table 1.2), cation sorption can takes place only on the deprotonated edge sites. This is the case for tectosilicates (quartz, cristobalite). 

For comparison with Tables I and II, Table lit gives the range and typical values of the mineral distributions observed in bituminous coals by the CCSEM and Mossbauer techniques, derived from studies of perhaps a hundred different bituminous coal samples in this laboratory. Some obvious differences in mineralogy are apparent. In addition to the difference in calcium dispersion and abundance already noted, it is seen that certain minerals common in bituminous coals, such as Fe-bearing clays (illite and chlorite) and siderite, are virtually absent in the low-rank samples of Tables I and II. Conversely, minerals such as barite (BaSO ), apatite (Ca5(P0 )30H), and other Ca, Sr phosphates are rather uncommon in bituminous coals. 

Factor-1 samples contain high concentrations of many trace elements, particularly boron and the transition elements Co, Cu, Mo, Ni, Pb, Zn, and V (Table III). These samples also contain illite (CR-2 core) and relatively high concentrations of analcime and oil (both cores) which suggests that adsorption of trace elements onto clay, altered tuffaceous material, and (or) organic matter may be important 1n controlling the distribution of these trace elements. The sulfide phase also may control the occurrence of these metals (10-11). Factor 1 samples also... 

MudMaster MudMaster A program for calculating crystallite size distributions and strain from the shapes of X ray diffraction peaks. D. D. Eberl, V. Drits, J. Srodon, and R. Nuesch, U.S. Geological Survey Open File Report 96 171, (1996) 46 pp and XRD measurement of mean thickness, thickness distribution and strain for illite and illite/ smectite crystallites by the Bertaut Warren Averbach technique. 

Illite. A group of three-layer, mica-like, and grey, light-green, or yellowish brown clay minerals, especially widely distributed in marine shales and soils derived from them of the general formula (H3O K)y(Al4.Fe4.Mg4,Mg6)(Si8 v.A1,)02o(OH)4, with y less than 2. 

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