Amounts Of Illite Research Articles

Dolomite, Limestone Facies, and Insoluble Residue--A Relationship?: ABSTRACT

Almost 600 insoluble-residue and quantitative X-ray analyses have been performed on samples collected from the Callville and Pakoon Formations (Pennsylvanian and Lower Permian) of southern Nevada. The gross lithologies present are limestone, dolostone, and carbonate-cemented sandstone. The insoluble residues range from 0.7 to 77.0% and consist of fine-sand size quartz with varying amounts of illite (clay). Plots of the total insoluble residue against percent dolomite show that more than 500 of the samples fall into either limestone (greater than 90% calcite) or dolostone (greater than 90% dolomite) end members. Plots of the dolomite percentage in the 100 remaining, mixed-calcite-dolomite mineralogy specimens versus total insoluble residue showed no obvious trends. Plots of the mixed-mineralogy specimens versus the illitic clay content likewise showed no obvious trends. Five limestone facies (micrite, sparse micrite, packed micrite, biopelsparite and oosparite) were recognized. No relation was found between limestone facies and percent total insoluble residue or between percent dolomite and limestone facies. End_of_Article - Last_Page 791------------

Weathering of micaceous clays in some Norwegian podzols

AbstractA study of the weathering of micaceous clays in some Norwegian podzols, includes semiquantitative estimates of minerals in the concentrated clay fractions which show a decrease in the amounts of illite and chlorite, and an increase in vermiculite and mixed-layer minerals upward in the profile. Illite, the dominant mineral at depth, weathers to hydrobiotite in the surface horizon of the profile. Subsequent weathering of hydrobiotite in this portion of the profile produces trioctahedral vermiculite and smectite, or intergrade smectite-chlorite.

Stratigraphy, Age, and Interregional Correlation of the Exshaw Formation, Alberta Rocky Mountains

ABSTRACT The Exshaw Formation of the Alberta Rocky Mountains and foothills consists of a lower, black shale unit and an upper, siltstone unit, which are separated by a gradational contact. At the type section on Jura Creek, near Exshaw, Alberta, the upper contact of the Exshaw is redefined so that the formation includes all, rather than merely the lower part, of an unbroken sequence of dark-yellowish orange-weathering calcareous siltstone. At the type section, the black shale unit is 33 ft thick and the siltstone unit 127 ft. X-ray diffraction data from the type section indicate that the shale is composed mostly of quartz and contains only minor amounts of illite, feldspar, and carbonates. The siltstone has considerably more calcite and dolomite than most of the shale. Throughout its area of outcrop, the Exshaw unconformably overlies limestones of the Devonian Palliser Formation, and is sharply (disconformably?) overlain by shales at the base of the Mississippian Banff Formation. The silts and clays, and some of the carbonaceous material in the black shale unit, were probably derived from soils and deposited in shallow-marine, euxinic lagoons. The siltstone unit was deposited in a regressive, marginal-marine environment of widespread, well-oxygenated tidal flats. Physical continuity is demonstrated between the Exshaw Formation and a) the lower two members of the Bakken Formation in the subsurface of southeastern Alberta and Saskatchewan, b) the Sappington Member of the Three Forks Formation in Montana. Conodont evidence from the Exshaw Formation and circumstantial conodont and spore evidence from the Sappington Member and Bakken Formation show the age of the Exshaw to be Devonian and Mississippian. The systemic boundary is probably positioned near the middle of the black shale unit. Evidence previously cited for the age of the Exshaw at Crowsnest Pass is shown to be more pertinent to the age of the overlying Banff Formation. End_Page 32-------------------------

Distribution of Silicate Minerals in Florida Bay: ABSTRACT

The predominantly carbonate sediments within Florida Bay contain small percentages of insoluble silicate minerals, ranging in our samples from 1.25 to 14.91% by weight. Quartz, chlorite, and montmorillonite compose most of the silicate fraction, with very minor amounts of illite and kaolinite. Clay-mineral distribution can be described by concentration gradients based on two end-member assemblages. A chloritic assemblage dominates in the eastern part of the bay, but declines westward; a montmorillonitic assemblage dominates the western bay and declines eastward. The two clay-mineral assemblages reflect different sources--chlorite from the Atlantic province, and montmorillonite from the Gulf of Mexico province. Shallow and subaerial carbonate mud banks and intervening basi s inhibit mixing waters bearing the two clay assemblages; the result is the relatively abrupt transition from one clay suite to another in the 30-40 mi span of Florida Bay. The clay mineral fractions of similar ancient carbonate reef trends would be expected to show analogous concentration gradients in the backreef area. End_of_Article - Last_Page 2039------------

Physical and Chemical Properties of Mississippi River Alluvial Valley and Delta Clays: ABSTRACT

End_Page 527------------------------------Areal distributions of clay suites of the central Gulf of Mexico area have been studied mainly by X-ray diffraction, using peak-height ratios as an index to the nature of clays. This approach alone yields little information regarding effects of depositional environments. The present study couples geochemical techniques with analysis of other environmental indicators and emphasizes effects of organic and inorganic processes associated with deposition and early diagenesis. Undisturbed samples from both active environments and deep borings were utilized. Samples from freshwater alluvial valley and upper deltaic-plain environments were compared with others from brackish and saline environments of the lower delta. Laboratory techniques included X-ray radiography, X-ray radiography, X-ray d ffraction, X-ray spectrography, atomic absorption spectrophotometry, and microsteam distillation. Clays deposited in channel and natural levee environments show little modification from the basic transported suite carried by the Mississippi (predominantly montmorillonite with appreciable amounts of illite and kaolinite). Minor differences attributed to seasonal fluctuations in flow regimes of major tributaries are detectable in suspended load and bottom samples. Percent organic C and cation-exchange capacities tend to decrease toward the river mouth. In the lower delta, properties of delta-front and prodelta clays show distinct gradients, reflecting velocity decrease, water-depth increase, salinity increase, and mixing with shelf clays. Clays become more kaolinitic, less calcium saturated, and more sodium saturated seaward from distributary mouths. In these environments high soluble salt content is associated with a distinct texture and lamination produced by salt flocculation. Integrated intensity ratio logs of montmorillonite-plus-illite/kaolinite from deep lower-delta borings not only exhibit trends related to delta progradation, but also show clay-mineral zonation resulting from shifting delta lobes. This zonation has been useful particularly in solving stratigraphic problems associated with diapiric mud-lump structures. Clays are introduced into upper deltaic plain fresh-water basins largely by overbank flow from the main distributaries. Paludal and lacustrine environments are characterized by low rate of detrital introduction, high rates of organic and inorganic chemical deposition, high pH (>8.0), and warm, stagnant water. Despite the fact that secondary minerals (siderite, calcium carbonate, pyrite, vivianite, etc.) in the form of nodules and cementing agents are abundant and form rapidly, the basic nature of the clay remains unaltered even after burial for several thousand years. End_of_Article - Last_Page 528------------

Carbonate and clay mineralogy of the Persian Gulf

The carbonate and clay mineralogy of 45 widespread Persian Gulf samples was determined. The trends in abundance of both the carbonate and clay minerals roughly parallel the long axis of the Gulf. The carbonate fraction of the relatively coarse-grained, carbonate-rich sediments along the southwest margin (Saudi Arabian coast) consists largely of aragonite and high-Mg calcite. The finergrained sediments along the northeast margin (Iranian coast) are relatively carbonate-poor and the dominant carbonate minerals are low-Mg calcite and dolomite. In individual samples, the carbonate fraction of less-than-sand size usually contains much more low-Mg calcite than the coarser fractions. Dolomite, at least traces of which were found in nearly every samples, is almost exclusively present in the fine fraction of individual samples. Dolomite may make up greater than 50% of the total carbonate fraction in some samples but in most cases is less important. Although primary dolomite has been reported from very shallow water in the Persian Gulf, the dolomite observed in this study is believed to have been derived from dust picked up from outcrops of ancient dolomites and perhaps from local rivers. The mineralogy of the carbonate fraction of the Persian Gulf appears to be controlled by the balance between organic carbonate processes (characterized by abundant aragonite and high-Mg calcite) and the amount of dust and river contribution (characterized by abundant dolomite and low-Mg calcite). The dominant clay mineral found in Persian Gulf sediments is an illite plus an illite-montmorillonite with approximately 10–20% expandable layers. This 10 Å material is followed in abundance by chlorite, a heterogeneous conglomeration of illite-montmorillonite with greater than 40% expandable layers and kaolinite, respectively. In general, the amount of illite plus illite-montmorillonite decreases with respect to chlorite in a direction away from the Iranian shore. The quantity of chlorite with respect to kaolinite decreases also in the same way.

Untersuchungen am Kupferschiefer in Nordwestdeutschland; Ein Beitrag zur Deutung der Genese bituminöser Sedimente

From a comparison of literature data on bituminous and non-bituminous sediments elements which seem to be characteristic for these strata have been selected to be analysed in the “Kupferschiefer”. Core samples from localities in N.W. Germany were available to be compared with the material from the area of ore grade deposits around Mansfeld-Richelsdorf. The mineral composition and the contents of CO 2 C, S, B, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Ba and Pb have been determined quantitatively in about 50 samples. The portion of carbonates in the brown-black, fine-layered marl with an average thickness between 20 and 50 cm is about 30 per cent. In the coastal areas dolomite is more abundant than calcite whereas in the sediment deposited at some distance from the shore calcite is the more predominant of the two. The occurrence of one or two cardonate minerals changes along the profile. An early diagenetic origin of the carbonates is assumed. The relatively high magnanese, and low strontium content, is proportional to the amount of carbonate. No relation between the abundant detrital silicates and quartz, and most of the above mentioned elements could be detected. Some albite and chlorite can be of diagenetic origin. The boron and rubidium content is proportional to the amount ofillite in the “Kupferschiefer”, as is to be expected. The V-, Crand Ni concentrations are related to the carbon content. The relationship is well developed. Mo and Co appear also to be related. These proportionalities and the origin of the large amounts of metals are discussed in terms of adsorption from and reaction with enhanced concentrations in sea water. No relation between the sulfide and the carbon content could be detected in the “Kupferschiefer”. The basin of Central Germany is characterized by the enrichment throughout of one or other of the sulfides of copper, lead and zinc. The degree of enrichment increases in this order of the elements. In the basin of Northern Germany large amounts of sulfides do only occur locally mostly in the coastal areas. In the northwestern part of the area of transgression, where the strongest marine influence is to be expected, the Cu-, Pb-, and Zn values of the “Kupferschiefer” are as low as in most of the other bituminous sediments. The vertical distribution of the metals and ores in several profiles widely separated are strikingly similar. The order of precipitation is: Cu/Ag, Pb, Zn, which is the order of decreasing solubility of the sulfides. The conditions of recent H 2S production in stagnant sea water and the precipitation of sulfides are discussed in relation to solubility data. Since a balance calculation shows that the amount of metals in the “Kupferschiefer” cannot be derived from “normal” sea water, an additional source must be considered.∗ Evidence is provided that several elements, V, Cr, Zn. Mo, etc. are fixed by iron oxides of red sandstones. Therefore the possibility arises that through the reduction of ferric iron these elements pass into solution. In this way the mentioned elements are mobilized from Rotliegend-sandstones into stagnant water. These considerations are in accordance with numerous geologic observations. All evidence in favour of a syngenetic metal accumulation is given in a special section. The homogeneous distribution of high sulfide contents at equal levels within a bed of small thickness and of low permeability for circulating solutions is strong support for a syngenetic origin. Secondary alterations of the mineral composition from supergene or hypogene processes have only disturbed the evidence for a syngenetic ore deposition on a local scale.

Correlation of Grain-Size Distribution and Mineralogy with Depositional Environment in the Dakota Formation (Cretaceous) of the San Juan Basin, New Mexico and Colorado: ABSTRACT

The depositional environment of units within the Dakota formation of the San Juan basin was determined by means of fossils, sedimentary structures, and facies relationships. Grain-size distribution, heavy-mineral content, and clay-mineral content were found to correlate well with the depositional environment in a manner similar to observations reported from modern sediments. Many depositional environments are represented in the Dakota formation, which grades from lenticular, non-marine sandstone and carbonaceous shale in the northwestern San Juan basin to regularly interstratified shale and very fine-grained sandstone in the southeastern San Juan basin. Dakota fluvial sandstones are fine-skewed and are generally poorly sorted. Dakota beach sandstones are coarse-skewed and well sorted, while Dakota offshore marine sandstones are fine-skewed and are generally moderately well sorted. The finer particles in Dakota offshore sandstones were winnowed from beaches and were deposited offshore. Dakota fluvial sandstones characteristically are fine-skewed. The finer particles in these fluvial sandstones were not winnowed and the competence of stream flow sets an upper limit to the size of particles transported. In a vertical series of samples from Dakota sandstones grading from nonmarine deposits below to marine deposits above, the degree of sorting increases upward into the lower part of the lowest marine sandstone (beach deposit) and gradually decreases in offshore sandstones above the beach sandstone. The change in skewness from coarse in the beach sandstone to fine in the fluvial and offshore marine sandstones is abrupt. Dakota non-marine shales contain much kaolinite with some illite. The amount of carbonaceous matter in the shales is inversely related to the amount of illite. Dakota marine shales contain much montmorillonite in addition to kaolinite and illite. Dakota sandstones derived from source areas north and west of the San Juan basin have a small, stable suite of heavy minerals in which zircon and tourmaline predominate. Most of these mineralogically simple sandstones are non-marine. Dakota marine sandstones, such as the Tres Hermanos and Twowells members, which were derived from source areas south of the San Juan basin, contain a suite of metamorphic minerals in addition to zircon and tourmaline. End_of_Article - Last_Page 540------------

Etude preliminaire des argiles eocenes, mio-pliocenes et actuelles de la region de Metlaoui-M'Dilla et du cap Bon (Tunisie)

Abstract Eocene and Mio-Pliocene formations of the Gafsa region are differentiated by their clay minerals. The clays of the El-Haria formation are composed of equal amounts of montmorillonite and kaolinite. The overlying Eocene marine clays of Djebel M'Dilla are composed of montmorillonite, illite and traces of kaolinite, and include a bed of clay containing montmorillonite and sepiolite-attapulgite. The continental Mio-Pliocene deposits around Djebel M'Dilla contain a suite of minerals including kaolinite, attapulgite, illite, montmorillonite and chlorite. These minerals apparently do not have authigenic characteristics. Diffractograms obtained from these deposits indicate pronounced crystallinity of the minerals. Mineralogic variation in the clay lenses shows that, from the base to the top, illite and, to a lesser degree, kaolinite, gain importance at the expense of the montmorillonite. At Cape Bon, the Oligocene is rich in kaolinite with subordinate amounts of illite and montmorillonite. Vindobonian, Pliocene and Recent deposits contain the same phyllites but with kaolinite and montmorillonite in equal proportions and a lesser percentage of illite. The uniformity exhibited by the Miocene clays--suggesting monotonous accumulation from a single source of supply--reaffirms the fact that the composition of clays depends more on the nature of the source of supply than on the diagenetic modification produced in the course of sedimentation. The montmorillonitic mineral of these deposits is an unstable phyllite intermediate between a classic montmorillonite in the Eocene and an ammersoite in the post-Eocene.

Concerning the association montmorillonite- analcime in the series of Stanleyville, Congo

Discusses the mineral associations in shales from an alternating series of late Jurassic sandstones and shales containing several zones of bituminous schists. The fine fractions of 13 samples of shales from different lithologic subdivisions were found to be similar, being essentially montmorillonitic, with minor amounts of illite and occasionally kaolinite. Analcime was identified in several samples; its occurrence in a predominantly montmorillonitic rock suggests that the original rock was volcanic in origin.

On the Amount of Illite in the Clays from Arable Soils. (Continued)

On the Amount of Illite in the Clays from Arable Soils. (Continued)

On the Amount of Illite in the Clays from Arable Soils.

On the Amount of Illite in the Clays from Arable Soils.

Petrology of the Pennsylvanian underclays of Illinois

The results of a detailed petrologic investigation of underclays of various types occurring beneath the coals in Illinois are presented. The mineral composition of the clay grade was determined by optical, X-ray, and chemical criteria, frequently following sedimentation and supercentrifuge separations into fractions sufficiently simple mineralogically so that the analytical data could be definitely interpreted. Constituents coarser than clay were identified with the petrographic microscope. Base-exchange capacity values and textural characteristics are presented and discussed. The completely noncalcareous underclays occurring most commonly beneath coal No. 2 and older coals are composed largely of kaolinite. Varying amounts of illite and quartz are also present. Occasional beds are found in these underclays which are composed almost wholly of a distinctive member of the illite clay mineral group. The calcareous underclays and those grading from noncalcareous to calcareous which occur beneath younger coals contain illite as the essential clay mineral constituent. Except for variations in the calcite and quartz content and a slight concentration of limonite in a zone several inches below the coal, there is no evidence of variation in the mineral constitution or chemical composition within beds of the latter underclays as they are traced downward from the overlying coal. The analytical data definitely indicate no appreciable vertical variation of the completely noncalcareous underclays. Underclays seemingly have been subjected little or not at all to processes similar to those forming modem soils. The significance of the petrographic data on the origin and genesis of underclays is discussed in detail.