Quantitative XRD bulk and clay mineralogical determination of paleosol sections of Unayzah and Basal Khuff clastics in Saudi Arabia

2012 ◽  
Vol 27 (2) ◽  
pp. 126-130 ◽  
Author(s):  
Shouwen Shen ◽  
Syed R. Zaidi ◽  
Bader A. Mutairi ◽  
Ahmed A. Shehry ◽  
Husin Sitepu ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Size Fraction ◽  
Xrd Analysis ◽  
Ratio Method ◽  
Type I ◽  
Rock Formations ◽  
Refinement Method

Quantitative X-ray diffraction (XRD) analysis is performed on 172 samples mainly containing paleosol sections of Unayzah and Basal Khuff clastics taken from the core of one well drilled by Saudi Aramco. Quantitative XRD bulk mineralogical determination is achieved using the Rietveld refinement method whereas quantitative XRD clay mineralogical determination of clay-size fraction is obtained using the reference intensity ratio method. The XRD results indicate that the samples from paleosol sections consist mainly of quartz and feldspar (microcline and albite) as framework constituents. Cement minerals include dolomite, hematite, anhydrite, siderite, gypsum, calcite, and pyrite. Clay minerals are important constituents in paleosols. The XRD results show that clay minerals in the samples are illite, mixed-layer illite/smectite, kaolinite, and chlorite. No discrete smectite is present in the samples. The clay mineral associations in these samples of paleosol sections can be classified into three types: Type I predominantly consists of illite and a mixed layer of illite/smectite; Type II of kaolinite; and Type III of illite and a mixed layer of illite/smectite, but also significant amounts of kaolinite. The change of clay mineral association type with sample depth can indicate the change of paleoclimate and paleoenvironment. For example, kaolinite usually forms under strongly leaching conditions such as abundant rainfall, good drainage, and acid waters. Therefore, XRD mineralogical data of paleosol sections are important for petroleum geologists to study paleoclimate and paleoenvironment and to predict the reservoir quality of the associated rock formations.

Thermogravimetry/evolved water analysis (TG/EWA) combined with XRD for improved quantitative whole-rock analysis of clay minerals in sandstones

Clay Minerals ◽  
1995 ◽  
Vol 30 (1) ◽  
pp. 27-38 ◽  
Author(s):  
D. M. Thornley ◽  
T. J. Primmer
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Water Analysis ◽  
Infrared Detector ◽  
Size Fraction ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Northern North Sea ◽  
Rock Analysis

AbstractCurrent methods of quantitative whole-rock clay mineral analysis of sandstones often provide little more than an estimate of clay mineral abundances, especially where the total clay mineral content is <10 wt% of the sandstone. More accurate determinations of clay mineral abundance in the whole rock can be made by combining thermogravimetry/evolved water analysis (TG/EWA) and X-ray diffraction (XRD) data. The TGA/EWA system incorporates a purpose built thermobalance linked to a water specific infrared detector which is used to measure quantitatively the clay mineral dehydroxylation water evolved from the whole rock when heated from 250°C to 900°C. This gives a measure of the total hydroxyl content of the clay minerals in the whole rock which, when combined with XRD analysis of a separated clay size-fraction, enables individual clay mineral abundances in the whole-rock sample to be determined. Results on artificial sand/clay mineral mixtures prepared with known amounts of different clay minerals (chlorite, illite and kaolinite) show that the accuracy of the combined method is most influenced by the accuracy of the XRD data. Errors associated with TG/EWA were found to be negligible by comparison. A case study is included in which the technique has been used to determine accurately the illite abundance in the Magnus Sandstone Reservoir, Northern North Sea.

Jurassic clay mineral assemblages and their post-depositional alteration: upper Great Estuarine Group, Scotland

1987 ◽  
Vol 124 (3) ◽  
pp. 261-271 ◽  
Author(s):  
Julian E. Andrews
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Middle Jurassic ◽  
Water Circulation ◽  
Hot Water ◽  
Geothermal Gradients ◽  
Fine Grained ◽  
Igneous Intrusions ◽  
Mineral Assemblages

AbstractClay minerals from Middle Jurassic lagoonal mudrocks, siltstones and silty fine-grained sandstones of the upper Great Estuarine Group (Bathonian) are divided into four assemblages. Assemblage 1, the most common assemblage, is rich in mixed-layer illite–smectite with attendant illite and kaolinite. Assemblage 2 is dominated by smectitic clay. These assemblages are indicative of primary Jurassic deposition. Illite and kaolinite were probably derived from the weathering of older rocks and soils in the basin hinterland and were deposited in the lagoons as river-borne detritus. The majority of smectite and mixed-layer illite–smectite is interpreted as the argillization product of Jurassic volcanic dust, also deposited in the lagoons by rivers. Near major Tertiary igneous intrusions these depositional clay mineral assemblages have been altered. Assemblage 3 contains smectite-poor mixed-layer illite–smectite, whilst Assemblage 4 contains no smectitic clay at all. Destruction of smectite interlayers occurred at relatively shallow burial depths (< 2500 m) due to enhanced geothermal gradients and local convective hot-water circulation cells associated with the major Tertiary igneous intrusions.

The transformation of feldspars and muscovite to clay minerals in (Ca,Mg)-carbonate bearing hydrothermal media

Clay Minerals ◽  
1980 ◽  
Vol 15 (3) ◽  
pp. 263-274 ◽  
Author(s):  
V. A. Frank-Kamenetskii ◽  
N. V. Kotov ◽  
A. A. Rjumin
Keyword(s):  
Elevated Temperature ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Sedimentary Rocks ◽  
Mineral Formation ◽  
Hydrothermal Conditions ◽  
Layer Silicates

AbstractExperimental transformations of feldspars and muscovites following additions of magnesite and dolomite have been studied at PH2O = 1 kbar, T = 200–600°C. Formation of layer silicates such as smectite, 7 Å (Mg,Al)-serpentine, some mixed-layer phases and other minerals is shown to be a function of the composition of the starting materials, temperature and run duration. It is established that 1 M- and 2 M1-phlogopites are formed from 1 M- and 2 M1-muscovites, respectively, under Mg-bearing hydrothermal conditions. Some causes of variations in the composition of 7 Å (Mg,Al)-serpentines at elevated temperature as a function of the composition of hydrothermal media are given. These data may be used to explain the main characteristics of clay mineral formation from feldspar- and muscovite-bearing sedimentary rocks during their alteration in postdiagenetic and metasomatic processes.

Land erosion and associated evolution of clay minerals assemblages from soils to artificial lakes in two distinct climate regimes in Portugal and Brazil

Clay Minerals ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 161-179 ◽  
Author(s):  
R. Fonseca ◽  
F. J. A. S. Barriga ◽  
K. Tazaki
Keyword(s):  
Comparative Study ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Climatic Conditions ◽  
Soil Productivity ◽  
Reservoir Sediments ◽  
Complex Transformation ◽  
Parent Rocks ◽  
Transformation Mechanisms

AbstractGiven that reservoirs contain most of the leached materials from soils, we have studied the sediments accumulated in the bottom of two groups of reservoirs developed under different climatic conditions and thus with contrasting rates of weathering/erosion regimes. Through detailed comparative study of clay minerals of the parent rocks and soils with the clay fractions of the dam sediments, we have concluded that, during cycles of erosion-transport-deposition, the leached materials have complex transformation mechanisms, making them much more active in the environment. All clay-mineral groups are well represented in the reservoir sediments, including abundant mixed-layer and partly disordered minerals. Moreover, the sediments are nutrient-rich and potentially useful as agricultural fertilizers and hence in reversing the declining soil productivity in some regions.

Clay mineral formation and transformation in rocks and soils

1984 ◽  
Vol 311 (1517) ◽  
pp. 241-257 ◽  
Keyword(s):  
Ion Exchange ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Solution Chemistry ◽  
Ocean Floor ◽  
Mineral Formation ◽  
Dioctahedral Smectite ◽  
Diagenetic Environment ◽  
Floccule Size

Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for die origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favouring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again.

Clay mineralogy of the Permo-Triassic strata of the British Isles: onshore and offshore

Clay Minerals ◽  
2006 ◽  
Vol 41 (1) ◽  
pp. 309-354 ◽  
Author(s):  
C. V. Jeans
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
North Sea ◽  
Mixed Layer ◽  
Early Stage ◽  
Regional Distribution ◽  
Clay Mineralogy ◽  
British Isles ◽  
Mineral Assemblages ◽  
Red Bed

AbstractThe regional distribution, mineralogy, petrology and chemistry of the detrital and authigenic clay minerals associated with the Permo-Triassic strata (excluding the Rotliegend: see Ziegler, 2006; this volume), of the onshore and offshore regions of the British Isles are reviewed within their stratigraphical framework. The origin of these clay minerals is discussed in relation to current hypotheses on the developments of the Mg-rich clay mineral assemblages associated with the evaporitic red-bed Germanic facies of Europe and North Africa.Composite clay mineral successions are described for seven regions of the British Isles — the Western Approaches Trough; SW England; South Midlands; Central Midlands; the Cheshire Basin; NE Yorkshire; and the Central North Sea. The detrital clay mineral assemblages of the Early Permian strata are variable, consisting of mica, smectite, smectite-mica, kaolin and chlorite, whereas those of the Late Permian and the Trias are dominated by mica, usually in association with minor Fe-rich chlorite. The detrital mica consists of a mixture of penecontemporaneous ferric mica, probably of pedogenic origin, and recycled Pre-Permian mica. In the youngest Triassic strata (Rhaetian), the detrital clay assemblages may contain appreciable amounts of poorly defined collapsible minerals (irregular mixed-layer smectite-mica-vermiculite) and kaolin, giving them a Jurassic aspect. There are two types of authigenic clay mineral assemblages. Kaolin may occur as a late-stage diagenetic mineral where the original Permo-Triassic porewaters of the sediment have been replaced by meteoritic waters. A suite of early-stage diagenetic clay minerals, many of them Mg-rich, are linked to the evaporitic red-bed facies — these include sepiolite, palygorskite, smectite, irregular mixed- layer smectite-mica and smectite-chlorite, corrensite, chlorite and glauconite (sensu lato). The sandstones and mudstones of the onshore regions of the British Isles display little or no difference in their detrital and authigenic clay mineral assemblages. In contrast, the sandstones of the offshore regions (North Sea) show major differences with the presence of extensive chloritic cements containing Mg-rich and Al-rich chlorite, irregular mixed-layer serpentine-chlorite, and mica.

Complex permittivity and clay mineralogy of grain-size fractions in a wet silt soil

Geophysics ◽  
2008 ◽  
Vol 73 (3) ◽  
pp. J1-J13 ◽  
Author(s):  
Steven Arcone ◽  
Steven Grant ◽  
Ginger Boitnott ◽  
Benjamin Bostick
Keyword(s):  
Grain Size ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Complex Permittivity ◽  
Mineral Content ◽  
Size Fraction ◽  
Clay Mineralogy ◽  
Free Water ◽  
Size Fractions ◽  
Grain Size Fractions

We determined the complex permittivity and clay mineralogy of grain-size fractions in a wet silt soil. We used one clay-size fraction and three silt-size fractions, measured permittivity with low error from [Formula: see text] with time-domain spectroscopy, and estimated mineral weight percentages using X-ray diffraction (XRD). The volumetric water contents were near 30%, and the temperature was [Formula: see text]. For the whole soil, standard fractionation procedures yielded 2.4% clay-size particles by weight, but XRD showed that the phyllosilicate clay minerals kaolinite, illite, and smectite made up 17% and were significantly present in all fractions. Above approximately [Formula: see text], all real parts were similar. Below approximately [Formula: see text], the real and imaginary permittivities increased with decreasing grain size as frequency decreased, and the imaginary parts became dominated by direct-current conduction. Similarly, below approximately [Formula: see text], the measured permittivity of montmorillonite, a common smectite, dominated that of the other clay minerals. Total clay mineral and smectite mass fractions consistently increased with decreasing grain size. Below [Formula: see text], a model with progressively increasing amounts of water and parameters characteristic of montmorillonite matches the data well for all fractions, predicts permittivities characteristic of free water in smectite structural galleries, and shows that the similar real parts above [Formula: see text] are caused by a small suppression of the high-frequency static value of water permittivity by the smectite. We conclude that the clay mineral content, particularly smectite, appears to be responsible for permittivity variations between grain-size fractions. Small model mismatches in real permittivity near the low-frequency end and the greater fractions of kaolinite and illite suggest that the total clay mineral content might have been important for the coarser fractions.

Clay minerals in shales of the Lower Silurian Longmaxi Formation in the Eastern Sichuan Basin, China

Clay Minerals ◽  
2017 ◽  
Vol 52 (2) ◽  
pp. 217-233
Author(s):  
Geng Yi-Kai ◽  
Jin Zhen-Kui ◽  
Zhao Jian-Hua ◽  
Wen Xin ◽  
Zhang Zhen-Peng ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Shale Gas ◽  
Mineral Content ◽  
High Pressures ◽  
Gas Reservoirs ◽  
Longmaxi Formation ◽  
Lower Silurian ◽  
Layer I

AbstractThe present study examines the characteristics of clay minerals in shale gas reservoirs and their influence on reservoir properties based on X-ray diffraction and scanning electron microscopy. These analyses were combined with optical microscopy observations and core and well-log data to investigate the genesis, distribution characteristics, main controlling factors and pore features of clay minerals of the Lower Silurian Longmaxi Formation in the East Sichuan area, China. The clay mineral assemblage consists of illite + mixed-layer illite-smectite (I-S) + chlorite. This assemblage includes three sources of clay minerals: detrital, authigenic and diagenetic minerals. The lower section of the Longmaxi Formation in the Jiaoshiba area has sealing ability which resulted in abnormal high pressures during hydrocarbon generation which inhibited illitization. Therefore, an anomalous transformation sequence is present in which the mixed-layer I-S content increases with depth. This anomalous transformation sequence can be used to infer the existence of abnormal high pressures. The detrital components of the formation also affect the clay-minerals content indirectly, especially the abundance of K-feldspar. The transformation of mixed-layer I-S to illite is limited due to the limited availability of K+, which determines the extent of transformation. Three types of pores were observed in the shale reservoir rocks of the Longmaxi Formation: interparticle (interP) pores, intraparticle (intraP) pores and organic-matter pores. The clay-mineral content controls the development of intraP pores, which are dominated by pores within clay particles. For a given clay mineral content, smectite and mixed-layer I-S were more conducive to the development of shale-gas reservoirs than other clay minerals.

Determination of the type of stacking in a mixed-layer clay mineral from Kinnekule

Clay Minerals ◽  
1967 ◽  
Vol 7 (1) ◽  
pp. 113-115
Author(s):  
G. L. Morelli ◽  
L. Favretto ◽  
A. M. Byström Asklund
Keyword(s):  
Clay Mineral ◽  
Mixed Layer
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