Samples from three well cores in the Pipe Creek Junior Reef (Niagaran-Cayugan) in the' Wabash Formation of northeastern Indiana revealed an indirect and imperfect relationship between dolomite and clay content. A microscopic examination of the larger than two micron fractions of residues that were insoluble in acetic acid, and semi-quantitative X-ray analyses of the smaller than two micron fractions revealed illite to be the only clay mineral present in 91 samples. Illite comprised approximately 50 percent of the insoluble residue and more than 90 percent of the aluminum oxide-containing minerals. No magnesium silicates were found.Illite and dolomite contents were calculated from spectrochemical analyses of Al203 and MgCO3 respectively in 94 reef-influenced samples from three Indiana Geological Survey well cores. The regression and linearity of the dolomite/illite relationship revealed an imperfect correlation in two of the three cores.Nineteen thin sections of textural' varieties, from the core that did not reveal a strong illite/dolomite correlation, and eight thin sections from a portion of interbedded limestones and dolostones in the pipe Creek Junior quarry reef flank revealed the authigenetic origin of dolomite and the probable detrital origin of illite. The concentration of illite and other insolubles by post-micritization microstylolitization occurred along seams of carbonate solution and high permeability which developed selectively within the micritic matrices. Dolomite selectively crystallized in those more permeable sediments following the complete or nearly complete lithification of the reef.Ball State UniversityMuncie, IN 47306

Engineered organoclays are 2:1 phyllosilicate soils that have been synthesized with a controlled interlayer organic phase to exhibit enhanced strength, lower compressibility, and stronger retention of organic compounds. Engineered organoclays are highly sorptive, and have a variety of potential engineering applications as sorbents or amendments in engineered earthen barrier systems. Previous studies examined the impact of the organic coating on a soil's physical properties; however, the geochemical behaviors of organoclays, especially their interaction with organic compounds at the micro-scale, remained relatively unquantified. This study investigated the engineering behavior of montmorillonite modified with a variety of quaternary ammonium cations (QAC clays) with controlled structure and density of loading. Molecular dynamics simulations were used to model the surfactant arrangement, geochemical processes in the QAC-clay interlayer, including organic compound sorption and mass transport, as well as the surface electrokinetics of suspended QAC-clay particles. All simulations were carried out based on the combined force field of ClayFF and the Consistent-Valence Force Field to ensure the accuracy of the simulation results, and results yielded insight into the prediction of synthesized QAC-clay behaviors as sorptive material for non-polar organic compounds.

The objective of the work described in this thesis was to understand sorption reactions of uranium occurring at the water-clay mineral interfaces in the presence and absence of arsenic and other inorganic ligands. Uranium(VI) removal by clay minerals is influenced by a large number of factors including: type of clay mineral, pH, ionic strength, partial pressure of CO2, load of the sorbent, total amount of U present, and the presence of arsenate and other inorganic ligands such as sulfate, carbonate, and phosphate. Both sulfate and carbonate reduced uranium sorption onto IBECO bentonite due to the competition between SO42- or CO32- ions and the uranyl ion for sorption sites, or the formation of uranyl-sulfate or uranyl-carbonate complexes. Phosphate is a successful ligand to promote U(VI) removal from the aqueous solution through formation of ternary surface complexes with a surface site of bentonite. In terms of the type of clay mineral used, KGa-1b and KGa-2 kaolinites showed much greater uranium sorption than the other clay minerals (STx-1b, SWy-2, and IBECO montmorillonites) due to more aluminol sites available, which have higher affinity toward uranium than silanol sites. Sorption of uranium on montmorillonites showed a distinct dependency on sodium concentrations because of the effective competition between uranyl and sodium ions, whereas less significant differences in sorption were found for kaolinite. A multisite layer surface complexation model was able to account for U uptake on different clay minerals under a wide range of experimental conditions. The model involved eight surface reactions binding to aluminol and silanol edge sites of montmorillonite and to aluminol and titanol surface sites of kaolinite, respectively. The sorption constants were determined from the experimental data by using the parameter estimation code PEST together with PHREEQC. The PEST- PHREEQC approach indicated an extremely powerful tool compared to FITEQL. In column experiments, U(VI) was also significantly retarded due to adsorptive interaction with the porous media, requiring hundreds of pore volumes to achieve breakthrough. Concerning the U(VI) desorption, columns packed with STx-1b and SWy-2 exhibited irreversible sorption, whereas columns packed with KGa-1b and KGa-2 demonstrated slow, but complete desorption. Furthermore, most phenomena observed in batch experiments were recognized in the column experiments, too. The affinity of uranium to clay minerals was higher than that of arsenate. In systems containing uranium and arsenate, the period required to achieve the breakthrough in all columns was significantly longer when the solution was adjusted to pH 6, due to the formation of the uranyl-arsenate complex. In contrast, when pH was adjusted to 3, competitive sorption for U(VI) and As(V) accelerated the breakthrough for both elements. Finally, experiments without sorbing material conducted for higher concentrations of uranium and arsenic showed no loss of total arsenic and uranium in non-filtered samples. In contrast, significant loss was observed after filtration probably indicating the precipitation of a U/As 1:1 phase.

Abstract The Late Devonian-Early Carboniferous Drummond Basin of central Queensland, Australia is one of the oldest units of the New England Fold Belt. Samples of authigenic clay minerals have been collected from across the Drummond Basin and analysed using mineralogic, isotopic and geochronologic techniques. X-Ray diffraction analysis on 36 samples selected from six exploration wells was carried out on volcaniclastic and argillaceous sandstones and mudstones of the Drummond Basin sequence in order to ascertain authigenic illite content. Sixteen samples were found to be suitable for K-Ar dating purposes, containing abundant illite and illite/smectite mixed layers (I/S). K-Ar age dating was carried out on these selected samples yielding three age groups at 300, 250 and 200 Ma. Temperature of formation was estimated for the authigenic illite and illite/smectite minerals, based on illite crystallinity and illite content of illite/smectite mixed layers. Two groups of temperatures have been delineated, with a high temperature assemblage of between 275¨¬C-320¨¬C and a low temperature assemblage of approximately 100¨¬C. When compared with the age groups, it is seen that the older event was typically hotter. Stable isotope compositions for the authigenic clay minerals were analysed with ¥äD and ¥ä18O values of between -68¢¶ to -117¢¶ and +7.5¢¶ to +14.4¢¶ (SMOW) respectively. Isotopic compositions for the fluid in equilibrium with the clay minerals were calculated using palaeotemperatures estimated from the clay mineralogy and range between -90¢¶ and -41¢¶ and -0.6¢¶ and +8.7¢¶ (SMOW) for hydrogen and oxygen respectively. These compositions are more depleted in deuterium and more enriched in 18O than those previously reported for basins in the region. The data also produced three groups of fluid compositions, which correlate with the age distributions delineated by the K-Ar geochronology. The first fluid composition, which correlated with the Permo-Carboniferous age (~300 Ma) is interpreted to result from a mixing of Permo-Carboniferous meteoric water with highly evolved formation water trapped within the Drummond Basin since deposition of the basin. The regional extensional event at the Permo-Carboniferous boundary, which initiated the opening of the Bowen Basin to the east of the Drummond Basin allowed meteoric water to percolate deep into the basin, enabling the growth of illite rich clay minerals at this time. The second fluid group is considered to represent the evolution of Late Triassic meteoric water migrating through the Drummond Basin during another extensional period in the region at approximately 200 Ma. This event precipitated a new period of clay mineral growth in the basin (reflected in the K-Ar dates), raised the geothermal gradient in the region and extended the crust, forming new sedimentary basins within the New England Fold Belt. The third assemblage of fluid compositions were found to be very similar to the Late Triassic group, with ¥äD and ¥ä18O values plotting very close to the Late Triassic meteoric water evolution trend. This is interpreted as representing the same fluid as that which produced the Late Triassic compositions and therefore the 250 Ma ages may represent partial resetting of older ages by the Late Triassic thermal episode. However, if it is assumed that these K-Ar ages are not old ages partially reset by a thermal event, the stable isotope data could represent a mixing of Mid-Late Permian meteoric water with formation water trapped in the basin. This event may represent the regional compressive Hunter-Bowen event and may be responsible for dewatering the basin before the Late Triassic extensional episode.

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Made available in DSpace on 2014-12-17T14:07:00Z (GMT). No. of bitstreams: 1 ElidaNMGP_DISSERT.pdf: 266264 bytes, checksum: 55a4fffa9b1f2a291d7fc9168a9d61cd (MD5) Previous issue date: 2011-04-16 / The destructive impact of improper disposal of heavy metals in the environment increases as a direct result of population explosion, urbanization and industrial expansion and technological developments. Argil are potential materials for adsorption of inorganic and the pelletization of it is required for use in adsorptive columns of fixed bed. The low cost and the possibility of regeneration makes these materials attractive for use in the purification process, capable of removing inorganic compounds in contaminated aquatic environments. In this work was made pellets of a mixture of dolomite and montmorillonite by wet agglomeration, in different percentages. The removal of Pb (II) was investigated through experimental studies, and was modeled by kinetic models and isotherms of adsorption. The materials were characterized using the techniques of XRD, TG / DTA, FT-IR, and surface area by BET method. The results showed the adsorption efficiency of the contaminant by the composite material studied in synthetic solution. The study found that the adsorption follows the Langmuir model, and the kinetics of adsorption follows the model of pseudosecond order / O impacto destrutivo da disposi??o inadequada de metais pesados no meio ambiente aumenta como resultado direto da explos?o populacional, urbaniza??o e expans?o industrial e tecnol?gica. Argilas s?o potenciais materiais para adsor??o de compostos inorg?nicos e a pelletiza??o destes ? necess?ria para utiliza??o em colunas adsortivas de leito fixo. O baixo custo e a possibilidade de regenera??o fazem desses materiais um atrativo para a utiliza??o em processos de purifica??o, capazes de remover compostos inorg?nicos em ambientes aqu?ticos contaminados. Neste trabalho foram preparados pellets com mistura de montmorilonita e dolomita atrav?s da aglomera??o por via ?mida, em diferentes raz?es. A remo??o de Pb(II) foi investigada, atrav?s de estudos experimentais, e foi modelada segundo modelos de cin?tica e isotermas de adsor??o. Os materiais foram caracterizados atrav?s das t?cnicas de DRX, TG/DTA, FT-IR, e ?rea superficial pelo m?todo BET. Os resultados mostraram a efici?ncia adsortiva do contaminante estudado pelo material composto em solu??o sint?tica e foi verificado que a adsor??o segue o modelo de Langmuir e a cin?tica de adsor??o segue o modelo de pseudo-segunda ordem

Atualmente a região de Criciúma é um grande pólo produtor de cerâmicas de qualidade, produzindo mais de 50% das exportações brasileiras de pisos e revestimentos cerâmicos, é um setor de sofisticada tecnologia de produção. Para o controle de qualidade do produto é fundamental a homogeneidade da composição mineralógica a partir do controle geológico na extração das matérias primas pelas mineradoras. Com a motivação de conhecimento das frentes de lavras foram aplicadas técnicas para a caracterização mineralógica em detalhe do material extraído de minas localizadas nos municípios de Turvo e Meleiro/SC, destinado à produção de cerâmicas pelas empresas da região. As rochas são argilitos cinza escuros intercalados com siltitos da Formação Rio do Rasto da Bacia do Paraná. Foram coletadas amostras dispostas verticalmente e analisadas através de difração de raios X para determinação mineralógica semiquantitativa em rocha total pelo método do pó e na fração < 2 e < 4 μm orientadas para identificação dos argilominerais pelas faces hkl = 00l. Foram feitas laminas delgadas para análise petrográfica através de microscopia ótica. Fragmentos foram analisados ao microscópio eletrônico de varredura por meio de imagens de elétrons secundários. Análises químicas de rocha total e da fração < 4 μm foram realizadas por espectrometria de fluorescência de raios X. Por microssonda eletrônica foram feitas microanálises químicas pontuais. A partir destes dados foi identificado o argilomineral montmorilonita do grupo da esmectita como argilomineral predominante, o interestratificado I/S e a ilita diagenética, além de quartzo, mica, feldspato potássico e plagioclásio como minerais detríticos abundantes. As análises mostram a existência de variação da composição mineralógica verticalmente com grande aumento da montmorilonita para a base e aumento do feldspato potássico para o topo na frente de lavra de Turvo e a presença do interestratificado I/S na base e esmectita e ilita/mica para o topo na mina de Meleiro. Estudos de detalhe por difratometria de raios X (determinação do parâmetro b) e microanálises WDS por microssonda eletrônica permitiram identificar como montmorilonita a espécie argilomineral do grupo das esmectitas. Desta forma sabendo-se que deve haver homogeneidade nos lotes da matéria prima explorada é fundamental a amostragem e caracterização mineralógica, sendo fundamental o controle geológico na exploração mineira. Através deste estudo espera-se facilitar o reconhecimento de áreas potenciais para a mineração e melhor adequação dos tipos de argilominerais estudados às necessidades da indústria cerâmica. / Currently the region of Criciúma/SC state is a great center of producing ceramics of quality, producing more than 50% of the Brazilian exportations of floor and ceramic coatings being a sector of sophisticated production technology. For the quality control of the product the homogeneity of the mineralogical composition from the geologic control in the extraction of raw materials is very important. With the motivation in the knowledge about the fronts it has been applied techniques for a detail mineralogical characterization of the material extracted in a mine located at Turvo and Meleiro city/SC, used as raw material in to the ceramics production by the companies in the region. The studied deposit is composed of intercalated gray clays with fine sandstones of Rio do Rasto Formation, in the Paraná Basin. Fourteen samples were collected and analyzed by petrographical analysis by microscopy methods. Analysis by X-ray diffraction (XRD) for mineralogical semiquantitative determination in total fraction by powder method and the analysis of oriented samples in the fractions < 2 and < 4 μm for identification of the clay minerals using 00l reflexions. Analysis by scanning electron microscopy (SEM) by secondary electrons allowed getting apparent threedimensional image of sample’s fragment. The chemical composition was determined by X-ray fluorescence spectrometer. Petrographic observations in thin section were also performed. Scanning electron microscope images was obtained in samples fragments by secondary electron method. Electron microprobe microanalysis was performed in one thin section. From this analysis were identified diagenetic smectite and illite as clay minerals predominant and the presence of quartz, mica, K-feldspar and plagioclase as detrital minerals. The analysis showed that there is a vertical variation in the mineralogical composition in the same exploitation front, with a large increase of smectite at the base and increasing K-feldspar to the top at Turvo mine and the occurrence of interstratified I/S in the base and smectite plus illite-mica at the top of Meleiro mine. Studies in detail by X-ray diffraction (determination of the b-parameter) and microanalysis by wavelength dispersive X-ray spectroscopy have identified montmorillonite clay mineral as the smectite mineral specie. Knowing that there should be uniformity in storages of raw material used, sampling and mineralogical characterization is fundamental in geological control of the mine. By this study we expect to favor the recognition of new potential areas for exploitation and better adequacy of the studied clay mineral types to the needs of the ceramic industry.

A Praia do Cassino, localizada no sul do Brasil, é freqüentemente coberta por extensivos depósitos de lama, ocasionando importantes efeitos de curta e longa duração. Alterações no volume das precipitações interferem diretamente no escoamento fluvial e, conseqüentemente, no volume de sedimentos que aportam na Lagoa dos Patos. Dados do regime de precipitação ao longo de 15 estações pluviométricas no período de 1968 a 2008 foram analisados estatisticamente e correlacionadas com eventos de El Niño e La Niña e com a ocorrência de lama na praia do Cassino. Períodos de El Niño e La Niña estão associados com precipitações acima e abaixo da normal, respectivamente, principalmente durante a primavera. Além disso, as anomalias climáticas apresentam influência potencial nos depósitos lamíticos do Cassino. Durante os eventos de El Niño são registradas precipitações mais intensas e, com um tempo de resposta mais rápido a partir do início da anomalia no Oceano Pacífico, além de um intervalo de tempo menor entre os eventos de deposição. As precipitações nas bacias da região sul, nas adjacências da Lagoa dos Patos, apresentam uma forte relação com esta anomalia. Em eventos de La Niña são observadas precipitação mais moderadas além de um período de tempo maior entre o início da anomalia negativa na TSM no Oceano Pacífico e os depósitos de lama. A bacia hidrográfica localizada ao norte da Lagoa dos Patos apresenta uma influência predominante sobre a precipitação durante esse evento. Foi analisada a provável fonte mineralógica das argilas presentes na praia do Cassino e adjacências a Lagoa dos Patos, por meio de difratometria de raio-X. A esmectita é o argilomineral predominante na plataforma continental e praia do Cassino enquanto que na Lagoa dos Patos o argilomineral mais abundante é a ilita. A aplicação da análise estatística paramétrica e multivariadas, juntamente com pesquisas bibliográficas permitiram definir as principais fontes de dispersão da lama na região costeira. / Cassino Beach, placed in the south of Brazil, is frequently covered by extensive deposition of mud which causes important short and long term effects on the beach environment, as well as on the tour activities of the region. Oscillations on the volume of rainfall interferes directly on the basins fluvial outflow and consequently on the volume of sediments that flow into Patos Lagoons System. Data record of the rainfall regime of fifteen rain gauge stations in the period between 1968 and 2008 were analyzed statistically and correlated with the events of El Niño and La Niña and with the occurrence of mud in Cassino beach. The periods are associated with rainfall that is above and below average both El Niño and La Niña occur, especially during spring. Frequently climate anomalies have potential influenced on the mud deposition in Cassino Beach. Duriing El Niño’s events, more intense rainfall is registered and its response is faster considering the time of the beginning of the anomaly in the Pacific Ocean. Besides that the interval between the events of deposition have become shorter. Rainfall in the south basin region adjacent to the Patos Lagoons Systems, have a strong relation with this anomaly. During La Niña’s events more moderate rainfalls are observed, as well as a longer interval between the beginning of the negative anomaly in the sea surface temperature in the Pacific Ocean and the deposition of mud. The basin drainage located on the north of Patos Lagoons Beach has a predominant influence over rainfall during this event. Eventually, the presumable mineral source of the clay found in Cassino Beach and adjacent to Patos Lagoons Systems was analyzed through x-ray diffraction. Smectite are the predominant clay minerals on the continental platform and on Cassino Beach while the sediment found in Patos Lagoons Systems presents higher concentration of iIlite. The sources and dispersal mud in the coastline region was defined with used the parametric and multivariate statistical analysis and bibliographical review.

This thesis presents the results of research undertaken in the south Cotswolds. Emphasis is placed on the engineering geological aspects of planning and construction on hillslopes, many of which have been superficially disturbed by cambering and landslipping. Special attention is paid to the geotechnical properties of the mudstone/clay horizons of the Fuller’s Earth and the Rhaetic, with emphasis on a study of the residual shear strength parameters. During the examination of numerous gulls in the Blue Lias at Radstock, a simple classification scheme was devised for the various extension styles produced in the interbedded limestone and clay sequence. The engineering significance of these phenomena is discussed. At Radstock cambering has taken place over the Rhaetic, especially the highly plastic Cotham Beds; these horizons have been investigated at this and other localities. Superficial structures are not well depicted on conventional geological maps. An attempt is made to determine to what extent they may be identified by engineering geomorphological mapping. Only disturbances which rupture the ground surface are clearly discernible and hence reliably depicted by this type of mapping; moreover it is shown that land use can obscure evidence of past instability. Engineering geomorphological mapping has been used as a preliminary study in the realignment of the A46 north of Bath. The proposed routes are discussed and some of the potential problems highlighted. It is demonstrated that false colour infra-red photography can be of considerable use in helping to identify areas of ground disturbance. A study of the geotechnical properties of the Fuller’s Earth shows an increase in “clay fraction”, expanding lattice clay minerals, plasticity and oxidation as weathering proceeds, with a corresponding drop in shear strength, bulk unit weight and calcite percentage. The presence of thin limestone bands modifies this profile. Calcite is found to have a significant effect on the plasticity of the Fuller’s Earth. The use of the Bromhead ring shear apparatus to determine residual strength has enabled many samples to be tested at normal loads up to 600 kPa; a number of advantages over the conventional shear box are discussed. The parameter φ’r is found to be stress dependent and as a result previously published correlations with other data are critically assessed and the choice of φ’r in engineering practice is considered.

Le Sud du Brésil est une région où l'agriculture est très intensive et la pression sur les sols est beaucoup plus importante que dans la région amazonienne. Ainsi, il est nécessaire de développer des études qui relient le développement du sol avec son matériau source respectif, en détaillant les transformations dans la zone de transition sol-roche et ses implications pour les activités environnementales et humaines. Dans ce contexte, ce travail vise à: (i) caractériser les aspects minéralogique, pédochimique et géochimiquedes profils d'altération développés en l'absence d'action humaine ou avec une intervention minimale; (ii) caractériser qualitativement et semi-quantitativement les minéraux primaires et les minéraux pedogenic dans les sols insérés dans les régions importantes de l'écosystème du Rio Grande do Sul; et (iii) évaluer l'impact des différentes intensités de pâturage sur la minéralogie d’un Oxisol sous système intégré de production soja-élevage dans le sud du Brésil. Cette étude concerce des sols du Rio Grande do Sul dont le climat subtropical (températures moyennes annuelles ~17°C, précipitations moyennes annuelles ~1800 mm/an) favorise l’accumulation de matiére organique ainsi que la formation de minéraux argileux 2:1. Les indices d'altération (Weathering Intensity Scale - WIS et Chemical Index of Alteration - CIA) établis à partir de la composition chimique des profils d'altération permettent de classer les profils selon leur degré d’altération qui correspond également à des compositions minéralogiques différentes (smectite, smectite + kaolinite, kaolinite). L'étude a montré que des sols formés à partir de la même roche ont des différences importantes liées aux différences climatiques et de relief. Finalement, après 12 ans de culture des sols avec un système intégré culture-élevage, les surfaces non pâturées présentent une proportions moins important de minéraux 2:1. D'autre part, les surfaces sous pâturage intensif et pâturage modéré présentent un comportement similaire attribué à une aluminisation plus élevée de la couche interfoliaire de minéraux 2:1. L'aluminisation plus élevée sous gestion intensive et modérée peut fixer une partie de l'aluminium dans la phase solide du sol, ce qui pourrait le rendre moins disponible pour les plantes et diminuer sa phytotoxicité. / O sul do Brasil é uma região com uma agricultura muito intensa e com grande pressão de uso do solo, consideravelmente mais intenso do que na região da Amazônia. Assim, é necessário desenvolver estudos que relacionem o desenvolvimento do solo com seu respectivo material de origem, detalhando as transformações na zona de transição solo-rocha e suas implicações para as atividades ambientais e humanas. Neste contexto, este trabalho tem como objetivo: (i) caracterizar os aspectos mineralógicos, pedoquimicos e geoquimicos dos perfis de alteração desenvolvidos na ausência ou mínima ação humana; (ii) caracterizar qualitativa e semi-quantitativamente os minerais primários e os minerais pedogênicos em solos inseridos em regiões ecossistêmicas importantes do Rio Grande do Sul; e (iii) avaliar o impacto de diferentes intensidades de pastejo na mineralogia de um Latossolo, sob sistema de produção integrada soja-bovinos de corte no sul do Brasil.Este estudo foi realizado em solos do Rio Grande do Sul, onde o clima subtropical (temperatura média anual ~ 17°C, precipitação anual média de 1800mm/ano) favorece o acúmulo de matéria orgânica ea ocorrência de argilominerais 2:1.Os índices de intemperismo (Weathering Intensity Scale - WIS e Chemical Index of Alteration - CIA), considerando a composição mineralógica dos perfis de alteração, indicaram a seguinte sequência crescente do grau de intemperismo: esmectita < caulinita - esmectita < caulinita. O estudo mostrou diferenças importantes nos solos, mesmo entre aqueles formados a partir do mesmo material de origem, devido às diferenças climáticas e de relevo. Por fim, após 12 anos sob um sistema integrado de produção de soja-bovinos de corte, as áreas não pastejadas apresentaram menor intensidade para os argilominerais 2:1. Por outro lado, as áreas sob pastejo intensivo e pastejo moderado apresentaram comportamento semelhante, devido à maior aluminização da entrecamada dos argilominerais 2:1. A maior aluminização sob pastejo intensivo e moderado pode ser um dreno de alumínio na fase sólida do solo, tornando-o menos disponível para as plantas e diminuindo sua fitotoxicidade. / The Southern Brazil is a region with a very intensive agriculture and the pressure on soil use is considerably more intense than in the Amazonian region. Thus, it is necessary to develop studies that relate the soil development with its respective source material, detailing the transformations in the soil-rock transition zone and its implications for the environmental and human activities. In this context, this work aims to: (i) characterize the mineralogical and pedochemical alterations and geochemical evolution the profiles of the alteration developed in the absence, or the minimal human action; (ii) characterize both qualitatively and semi-quantitatively the primary and pedogenic minerals present in soils of important ecosystems in Rio Grande do Sul; And (iii) evaluate the effect of grazing intensities on the mineralogy of an Oxisol, in an integrated soybean-cattle beef production system of southern Brazil. This study concerns soils of Rio Grande do Sul, where the subtropical climate (mean annual temperature ~17°C, mean annual precipitation 1800mm/yr) favored the accumulation of organic matter and occurrence of 2:1 clay minerals. The indexes of weathering (Weathering Intensity Scale - WIS and Chemical Index of Alteration - CIA), considering the mineralogical composition of the alteration profiles, indicated the following increasing sequence of the degree of weathering: smectite composition <kaolinite-smectite composition <kaolinite composition. The study showed that the soils have important differences, even between those formed from the same material of origin, due to climatic differences and relief. Lastly, after 12 years under an integrated soybean–beef cattle production system, the ungrazed areas presented lower intensity of 2:1 minerals. On the other hand, areas under intensive grazing and moderate grazing presented similar behaviour due to the higher aluminization of the interlayer of 2:1 minerals. The higher aluminization under intensive and moderate grazing managements may be a drain on aluminum in the soil solid phase, making it less available to plants and decreasing its phytotoxicity.