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Results for “Clays and Clay Minerals”

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At least 55 records · Page 3Linked to original sources
USGS1987

Diagenesis and fluid flow in the San Juan Basin, New Mexico - regional zonation in the mineralogy and stable isotope composition of clay minerals in sandstone.

The Westwater Canyon Member of the Upper Jurassic Morrison Formation is a relatively homogeneous, hydrologically continuous 100-m-thick sequence of massive fluvial sandstone, bounded above and below by relatively heterogeneous, hydrologically discontinuous units and has served as a primary conduit for fluids within this stratigraphic interval. Patterns of mineral-fluid reactions suggest a basinwide hydrologic regime in which warm, evolved fluids migrated up-dip from the center of the basin under the influence of a regional hydraulic head. -from Authors

American Journal of Science↗
USGS1973

Petrography and stratigraphy of glacial drift, Mesabi-Vermilion Iron Range area, northeastern Minnesota

Glacial deposits in the Mesabi-Vermilion Iron Range area consist of four major till units and associated glaciofluvial sediments. Particle-size data and pebble, heavy-mineral, clay-mineral, and percentage-soluble content were used in addition to field description of color and texture to describe and correlate the drift units. The lowermost till unit, basal till, occurs in only a small number of mines, but the mines are scattered across the entire Iron Range. The till is dark gray to dark greenish gray and brownish gray, sandy, silty, and calcareous. Pebbles are largely granitic and metamorphic rocks of local origin, but include limestone, dolomite, shale, basalt, felsite, agate, and gabbro. Clay-mineral content is largely illite. The age of the till is probably middle or early Wisconsin but could be pre-Wisconsin. The middle till unit, bouldery till, is the thickest and most widespread of the four tills. It is gray, yellow, red, orange, or brown, sandy, silty, noncalcareous and contains abundant cobbles and boulders. Pebbles are largely granitic and metamorphic rocks of local origin, but also include gabbro, basalt, and felsite in minor amounts. Montmorillonite is the most common clay mineral. Colored bouldery till below gray bouldery till may be a separate subunit distinguished largely on particle-size differences, but the overall characteristics are similar to the other bouldery till. The till was deposited by the Rainy lobe, which has a minimum age of 14,000 to 16,000 years before present. The uppermost, or surficial, tills were deposited contemporaneously by two minor sublobes of the Des Moines lobe about 12,000 years ago. Brown silty till occurs in the western and north-central part of the study area. It is light to medium brown, sandy, silty, and calcareous. Pebbles are largely granitic and metamorphic rocks of local origin, but include limestone, dolomite, shale, basalt, felsite, and gabbro. Clay-mineral content is largely mixed-layered montmorillonite and illite. Red clayey till occurs in the south-central part of the area. It is red to reddish brown, clayey, silty, and calcareous. Pebbles are similar to those in the brown silty till, but contain less limestone than the brown till. Glaciofluvial sediments are common between the various till units throughout the area, but are thickest near the east and near the west ends of the Iron Range.

Minnesota↗
USGS2011

Microbial reduction of structural iron in interstratified illite-smectite minerals by a sulfate-reducing bacterium

Clay minerals are ubiquitous in soils, sediments, and sedimentary rocks and could coexist with sulfate‐reducing bacteria (SRB) in anoxic environments, however, the interactions of clay minerals and SRB are not well understood. The objective of this study was to understand the reduction rate and capacity of structural Fe(III) in dioctahedral clay minerals by a mesophilic SRB, Desulfovibrio vulgaris and the potential role in catalyzing smectite illitization. Bioreduction experiments were performed in batch systems, where four different clay minerals (nontronite NAu‐2, mixed‐layer illite‐smectite RAr‐1 and ISCz‐1, and illite IMt‐1) were exposed to D. vulgaris in a non‐growth medium with and without anthraquinone‐2,6‐disulfonate (AQDS) and sulfate. Our results demonstrated that D. vulgaris was able to reduce structural Fe(III) in these clay minerals, and AQDS enhanced the reduction rate and extent. In the presence of AQDS, sulfate had little effect on Fe(III) bioreduction. In the absence of AQDS, sulfate increased the reduction rate and capacity, suggesting that sulfide produced during sulfate reduction reacted with the phyllosilicate Fe(III). The extent of bioreduction of structural Fe(III) in the clay minerals was positively correlated with the percentage of smectite and mineral surface area of these minerals. X‐ray diffraction, and scanning and transmission electron microscopy results confirmed formation of illite after bioreduction. These data collectively showed that D. vulgaris could promote smectite illitization through reduction of structural Fe(III) in clay minerals.

Geobiology↗
USGS2024

Considerations and applications of the illite/smectite geothermometer in hydrocarbon-bearing rocks of Miocene to Mississippian age

Empirical relationships between clay mineral transformations and temperature provide a basis for the use of clay minerals as geothermometers. Clay-mineral geothermometry has been applied mainly to diagenetic, hydrothermal, and contact- and burial-metamorphic settings to better understand the thermal histories of migrating fluids, hydrocarbon source beds, and ore and mineral formation. Quantitatively, the most important diagenetic clay mineral reaction in sedimentary rocks is the progressive transformation of smectite to illite via mixed-layer illite/smectite (I/S). Changes in both the illite/smectite ratio and ordering of I/S, as determined from X-ray powder diffraction profiles, correlate with changes in temperature due to burial depth. Although the smectite-to-illite reaction may be influenced by several factors, reaction progress appears to be strongly controlled by temperature. Studies show that the model proposed by Hoffman and Hower in 1979 is applicable in burial diagenetic settings from about 5 to 330 Ma, and includes most rocks about Miocene to Mississippian in age. Reliability of the I/S geothermometer is, however, dependent upon a good understanding of the rock's original clay-mineral composition. Changes in the ordering of I/S are particularly useful in the exploration for hydrocarbons because of the common coincidence between the temperatures for the conversion from random-to-ordered I/S and those for the onset of peak, or main phase, oil generation. Here, the utility of the I/S geothermometer is reviewed in hydrocarbon-bearing rocks of Miocene to Mississippian age. Using three common applications, the I/S geothermometer is compared to other mineral geothermometers, organic maturation indices, and grades of indigenous hydrocarbons. Good agreement between changes in ordering of I/S and calculated maximum burial temperatures or hydrocarbon maturity suggests that I/S is a reliable semiquantitative geothermometer and an excellent measures of thermal maturity.

Clays and Clay Minerals↗
USGS1959

Ion exchange in clays and other minerals

Ion exchange in clays and other minerals is dependent on the crystalline structure of the mineral and on the chemical composition of any solution in contact with the mineral. The structures of clay minerals and zeolites are briefly described to provide a background for the discussion of their ion-exchange reactions. Ion exchange in these minerals is a reversible chemical reaction that takes place between ions held near a mineral surface by unbalanced electrical charges within the mineral framework and ions in a solution in contact with the mineral. Generally the excess charge on the mineral is negative, and it attracts cations from the solution to neutralize this charge. The chemical reactions in ion exchange follow the law of mass action, but the reactions are restricted by the number of exchange sites on the mineral and by the strength of the bonding of the exchangeable cations to the mineral surface. Titration of H-clays with bases shows that montmorillonites and "illites" behave like a mixture of two or three different acids, whereas kaolinite, with an indefinite number of exchange sites, behaves like an indefinite number of acids. Ion-exchange capacity is measured in chemical equivalents of base adsorbed at pH 7. Each clay mineral has a range of exchange capacities because of differences in structure and in chemical composition. The ranges (in milliequivalents per 100 grams) are kaolinite, 3-15; halloysite (2H 2 O), 5-10; halloysite (4H 2 O), 40-50; montmorillonite, 70-100; "illite," 10-40; vermiculite, 100-150; glauconite, 11-20; attapulgite, 20-30; and allophane, 70. The common metallic cations found in exchange positions in clay minerals are Ca +2 , Mg +2 , Na + , and K + . At low pH values H + replaces other cations. The order of replaceability of the common cations has been found to be: Li + < Na + < K + < Rb + < Cs + and Mg +2 < Ca+2 < Sr +2 < Ba +2 Bivalent cations enter the exchange sites preferentially to univalent cations. The common exchangeable cation in most clay minerals in soils is Ca +2 . Other exchange phenomena discussed are anion exchange, fixation of cations and anions by clay minerals, effect of environment on cation exchange, and the exchange capacity of zeolites, of rocks, of other minerals, of organic matter and organic complexes, and of amorphous mineral material.

GSA Bulletin↗
USGS1960

Metallization and post-mineral hypogene argillization, Lost River tin mine, Alaska

The Lost River tin and tungsten deposit occurs in a buried granite pluton and in associated rhyolite dikes that intrude Paleozoic limestone. The dikes and parts of the granite were greisenized and then argillized irregularly. Metallization accompanied greisenization rather than argilli-zation, although both processes probably were closely related in time. Iron-zinc ratios in sphalerite indicate that the ore minerals were deposited at a temperature between 425°C and 740°C. This temperature is within the range of the temperatures at which topaz, a comman associate of the ore minerals, has been synthesized in the laboratory. The temperature of deposition of the ore minerals is above the temperature interval in which clay minerals are stable. Thus, clay minerals could not have formed while ore was being deposited. As temperatures fell and entered the stability range of the clay minerals, argillic alteration encroached upon greisen ores and wall rocks. Reaction rims between quartz and topaz indicate that kaolinite could have formed according to the following reaction: topaz + quartz + water + limestone -* kaolinite + fluorite + Cajj"C (Al,F)2Si04 + Si02 +3H2O+ CaCOa - Al2Si20B(OH)41 + CaF2 + H2CO3 The clay minerals, which formed from diverse rock types, consist of kaolinite, dickite, mixed-layered chlorite-montmorillonite, and minor montmorillonite, accompanied by variable amounts of muscovite and zinnwaldite. The dickite is most common in and near late veins that cut the earlier-formed greisen. Temperature is believed to be the principal agent governing the relations between ore deposition and argillization . Similar relations are to be expected in other high-temperature deposits where abundant veining and fracturing indicate that wall rocks reached an isothermal condition above a maximum temperature of 480°C during ore deposition.

Bering land bridge↗
USGS1956

Detailed mineral and chemical relations in two uranium-vanadium ores

Channel samples from two mines on the Colorado Plateau have been studied in detail both mineralogically and chemically. A channel sample from the Mineral Joe No. 1 mine, Montrose County, Colo., extends from unmineralized rock on one side, through a zone of variable mineralization, into only weakly mineralized rock. The unmineralized rock is a fairly clean quartz sand cemented with gypsum and contains only minor amounts of clay minerals. One boundary between unmineralized and mineralized rock is quite sharo and is nearly at right angles to the bedding. Vanadium clay minerals, chiefly mixed layered mica-montmorillonite and chlorite-monmorillonite, are abundant throughout the mineralized zone. Except in the dark "eye" of the channel sample, the vanadium clay minerals are accompanied by hewettite, carnotite, tyuyamunite, and probably unidentified vanadates. In the dark "eye," paramontroseite, pyrite, and marcasite are abundant, and bordered on each side by a zone containing abundant corvusite. No recognizable uranium minerals were seen in the paramontroseite zone although uranium is abundant there. Coaly material is recognizable throughout all of the channel but is most abundant in and near the dark "eye." Detailed chemical studies show a general increase in Fe, Al, U, and V, and a decrease in SO 4 toward the "eye" of the channel. Reducing capacity studies indicate that V(IV) and Fe(II) are present in the clay mineral throughout the channel, but only in and near the "eye" are other V(IV) minerals present (paramontroseite and corvusite). The uranium is sexivalent, although its state of combination is conjectural where it is associated with paramontroseite. Where the ore boundary is sharp, the boundary of introduced trace elements is equally sharp. Textural and chemical relations leave no doubt that the "eye: is a partially oxidized remnant of a former lower-valence ore, and the remainder of the channel is a much more fully oxidized remnant. A channel sample from the Virgin No. 3 mine, Montrose County, Colo., extends from weakly mineralized sandstone on both sides through a strongly mineralized central zone. The weakly mineralized zone is a poorly sorted sandstone with common detrital clay partings; chlorite and mixed layer mica-montmorrillonite are abundant interstitial to the quartz grains. No distinct vanadium or uranium minerals are recognizable, although the clay minerals are vanadium bearing. Euherdral pyrite grains and selenian galena are present but rare. The strongly mineralized rock is separated from the weakly mineralized rock by a narrow transition zone which only apporiximates the bedding planes. It contains abundant vanadium-bearing clay minerals (predominantly chlorite) interstitial to the quartz grains, and apparently replacing them. Paramontroseite is common and is intergrown with the clay minerals. Pyrite and marcasite are present, chiefly in or near the abundant blebs and fragments of carbonaceous material. Selenian galena is rarely present, and generally in or near carbonaceous material. Coffinite is the only uranium mineral idenitified; it is extremely fine grained and was identified only in X-ray diffraction patterns of heavy separates. Distribution of trace elements is not clear; some are consistently high in the strongly mineralized rocks, and some are consistently low. The trace element composition of the unmineralized rock is not known. Chemical studies show a very abrupt rise in the total U, V, and Fe from the weakly mineralized to strongly mineralized rock. Reducing-capacity studies indicate that most of the vanadium is present as V(IV), but some is present as V(V); that iron is present as both Fe(II) and Fe(III), the latter believed to have been present in the primary clays of the unmineralized rock; and that come of the uranium is present as U(VI) in addition to the U(IV) in the coffinite. All evidence points to weak oxidation of an ore once having a somewhat lower valence state. The channel samples from both the Mineral Joe No. 1 mine and the Virgin No. 3 mine are believe to have been essentially identical in mineralogy prior to oxidation by weathering: vanadium was present as V(III) in montroseite and V(IV) in the vanadium clays; uranium was present largely as U(IV) in coffinite and/or uraninite. The Mineral Joe No. 1 mine channel sample is now more fully oxidized. Vanadium clays are unquestionably formed abundantly during the primary mineralization, and they persist with a minimum of alteration during much of the weathering. They suggest that the vanadium is carried as V(IV) in the ore-forming fluids; it seems likely too that the uranium is carried as a U(VI) ion.

Trace Elements Investigations↗
USGS1985

CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.

Insoluble residues from three sequences of Paleozoic marine evaporites (Retsof salt bed in western New York, Salado Formation in south-eastern New Mexico, and Paradox Member of the Hermosa Formation in southeastern Utah) are rich in trioctahedral clays. Chlorite (clinochlore), corrensite (mixed-layer chlorite-trioctahedral smectite), talc, and illite (the only dioctahedral clay) are the dominant clay minerals; serpentine, discrete trioctahedral smectite (saponite), and interstratified talc-trioctahedral smectite are sporadically abundant. These clay-mineral assemblages differ chemically and mineralogically from those observed in most continental and normal marine rocks, which commonly contain kaolinite, dioctahedral smectite (beidellite-montmorillonite), illite, mixed-layer illite-dioctahedral smectite, and, in most cases, no more than minor quantities of trioctahedral clay minerals. The distinctive clay mineralogy in these evaporite sequences suggests a largely authigenic origin. These clay minerals are thought to have formed during deposition and early diagenesis through interaction between argillaceous detritus and Mg-rich marine evaporite brines.

Conference Paper↗
USGS1980

Sedimentology and geochemistry of surface sediments, outer continental shelf, southern Bering Sea

Present-day sediment dynamics, combined with lowerings of sea level during the Pleistocene, have created a mixture of sediments on the outer continental shelf of the southern Bering Sea that was derived from the Alaskan Mainland, the Aleutian Islands, and the Pribilof ridge. Concentrations of finer-grained, higher-organic sediments in the region of the St. George basin have further modified regional distribution patterns of sediment composition. Q-mode factor analysis of 58 variables related to sediment size and composition - including content of major, minor, and trace elements, heavy and light minerals, and clay minerals - reveals three dominant associations of sediment: 1. (1) The most significant contribution, forming a coarse-grained sediment scattered over most of the shelf consists of felsic sediment derived from the generally quartz-rich rocks of the Alaskan mainland. This sediment contains relatively high concentrations of Si, Ba, Rb, quartz, garnet, epidote, metamorphic rock fragments, potassium feldspar, and illite. 2. (2) The next most important group, superimposed on the felsic group consists of andesitic sediment derived from the Aleutian Islands. This more mafic sediment contains relatively high concentrations of Na, Ca, Ti, Sr, V, Mn, Cu, Fe, Al, Co, Zn, Y, Yb, Ga, volcanic rock fragments, glass, clinopyroxene, smectite, and vermiculite. 3. (3) A local group of basaltic sediment, derived from rocks of the Pribilof Islands, is a subgroup of the Aleutian andesite group. Accumulation of fine-grained sediment in St. George basin has created a sediment group containing relatively high concentrations of C, S, U, Li, B, Zr, Ga, Hg, silt, and clay. Sediment of the Aleutian andesite group exhibits a strong gradient, or "plume", with concentrations decreasing away from Unimak Pass and toward St. George basin. The absence of present-day currents sufficient to move even clay-size material as well as the presence of Bering submarine canyon between the Aleutian Islands and the outer continental shelf and slope, indicates that Holocene sediment dynamics cannot be used to explain the observed distribution of surface sediment derived from the Aleutian Islands. We suggest that this pattern is relict and resulted from sediment dynamics during lower sea levels of the Pleistocene.

Alaska↗
USGS2006

Influence of layer charge and charge distribution of smectites on the flow behaviour and swelling of bentonites

The influence of layer charge and charge distribution of dioctahedral smectites on the rheological and swelling properties of bentonites is examined. Layer charge and charge distribution were determined by XRD using the LayerCharge program [Christidis, G.E., Eberl, D.D., 2003. Determination of layer charge characteristics of smectites. Clays Clay Miner. 51, 644-655.]. The rheological properties were determined, after sodium exchange using the optimum amount of Na2CO3, from free swelling tests. Rheological properties were determined using 6.42% suspensions according to industrial practice. In smectites with layer charges of - 0.425 to - 0.470 per half formula unit (phfu), layer charge is inversely correlated with free swelling, viscosity, gel strength, yield strength and thixotropic behaviour. In these smectites, the rheological properties are directly associated with the proportion of low charge layers. By contrast, in low charge and high charge smectites there is no systematic relation between layer charge or the proportion of low charge layers and rheological properties. However, low charge smectites yield more viscous suspensions and swell more than high charge smectites. The rheological properties of bentonites also are affected by the proportion of tetrahedral charge (i.e. beidellitic charge), by the existence of fine-grained minerals having clay size, such as opal-CT and to a lesser degree by the ionic strength and the pH of the suspension. A new method for classification of smectites according to the layer charge based on the XRD characteristics of smecites is proposed, that also is consistent with variations in rheological properties. In this classification scheme the term smectites with intermediate layer charge is proposed. ?? 2006 Elsevier B.V. All rights reserved.

Applied Clay Science↗