Interstrat-An Expert System to Help Identify Interstratified Clay Minerals from Powder XRD Data: I. Description of the Program

Clay Minerals ◽  
1993 ◽  
Vol 28 (3) ◽  
pp. 445-460 ◽  
Author(s):  
L. A. J. Garvie
Keyword(s):  
Expert System ◽  
Knowledge Base ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
The State ◽  
Powder Xrd ◽  
Group Level

AbstractThe INTERSTRAT program has been specifically designed to aid the geologist in the identification of the phyllosilicates from powder XRD data. The program achieves this by comparing the experimental00ld-spacings with a knowledge base of diffraction parameters; a set of likely solutions is then displayed. The method employed by INTERSTRAT is analogous to that used by the clay mineralogist whereby the clays are initially identified down to the group level from the d(OOl) data alone. This procedure also utilises thed-spacings collected from clays that have been subjected to standard clay mineral treatments, i.e. glycolation and heating to 300~ and 500~ One of the most important features of INTERSTRAT is its knowledge base of d-spacings for the interstratified clay minerals in which calculatedd(00l)spacings for an individual mixed-layer clay are recorded with respect to its Reichweite, the state under which the d-spacings were collected and the percentage of the mixed-layer components.

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.

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.

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.

scholarly journals Order-disorder in clay mineral structures

Clay Minerals ◽  
2001 ◽  
Vol 36 (1) ◽  
pp. 1-14 ◽  
Author(s):  
A. Plançon
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Structural Characterization ◽  
Crystal Size ◽  
Structural Determination ◽  
Lattice Disorder ◽  
Layer Stacking ◽  
Polymorphous Transformations

AbstractSome recent works dealing with the concept of order-disorder in clay minerals are considered, including those aspects of order-disorder which appeared in the Brindley & Brown (1980) monograph, i.e. disorder in the distribution of cations, disorder in layer stacking, orderdisorder in mixed-layer systems and finite crystal size as a lattice disorder. Heterogeneity of samples and polymorphous transformations are also considered as other types of disorder. Most of these works emphasize that accurate structural characterization can only be obtained if several techniques are combined (e.g. XRD and IR, EXAFS and Mo¨ssbauer spectroscopies, etc.). Another conclusion is that accurate structural determination provides the key to the genesis of clays.

Interstrat—An Expert System to Help Identify Interstratified Clay Minerals from Powder XRD Data: II. Testing the Program

Clay Minerals ◽  
1994 ◽  
Vol 29 (1) ◽  
pp. 21-32 ◽  
Author(s):  
L. A. J. Garvie
Keyword(s):  
Expert System ◽  
Clay Minerals ◽  
Diffraction Data ◽  
Knowledge Bases ◽  
Powder Xrd ◽  
Text File ◽  
X Ray Diffraction ◽  
X Ray

AbstractINTERSTRAT is designed to help clay mineralogists identify clay minerals from powder X-ray diffraction data and is especially useful as an aid in the interpretation of interstratified clay minerals. This paper illustrates the use of the INTERSTRAT program in the identification of a set of interstratified clay minerals. One of the examples has been matched against the PDF and the answers compared with those obtained by INTERSTRAT. The most useful features of the program are the knowledge bases of diffraction parameters for the interstratified clay minerals, the ability of the program to compare the clays identified in more than one state and the hierarchical clay text file.

The origin of the Triassic clay assemblages of Europe with special reference to the Keuper Marl and Rhaetic of parts of England

1978 ◽  
Vol 289 (1365) ◽  
pp. 549-636 ◽  
Keyword(s):  
Special Reference ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
North Africa ◽  
Western Europe ◽  
Water Masses ◽  
Mineral Assemblages

Hypotheses are reviewed on the origin of the magnesium-rich Triassic clays which characterize the Germanic facies of western Europe and north Africa. Relations between clay minerals, megafacies and stratigraphy are described from 28 localities in the Triassic Keuper Marl, Tea Green Marl and Rhaetic sediments of England. Two clay mineral assemblages are recognized: (1) a detrital assemblage of mica with minor chlorite which occurs throughout all the sediments investigated, and (2) a neoformed assemblage of magnesium-rich clay minerals with a limited occurrence related to certain megafacies cycles which resulted from the transgression and regression of the Alpine facies into the Germanic facies; this assemblage includes sepiolite, palygorskite, chlorite, smectite, corrensite and irregular mixed-layer smectite/mica and smectite/chlorite minerals. The clay mineral neoformations resulted from reactions between the water masses in which the Germanic and Alpine facies were deposited. Controlling the distribution and types of minerals neoformed were the general and local variations in the chemistries of the Alpine and Germanic water masses, as well as competition for available magnesium from other mineral-forming reactions.

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