Fluid-rock interaction controlling clay-mineral crystallization in quartz-rich rocks and its influence on the seismicity of the Carboneras fault area (SE Spain)

NASA Astrophysics Data System (ADS)

Jimenez-Espinosa, R.; Abad, I.; Jimenez-Millan, J.; Lorite-Herrera, M.

2009-04-01

The Carboneras Fault zone is one of the longest fault in the Betic Cordillera (SE Spain) and it would be a good candidate to generate large magnitude earthquakes (Gracia et al., 2006). Seismicity in the region is characterised by low to moderate magnitude events, although large destructive earthquakes have occurred, which reveals significant earthquake and tsunami hazards (Masana et al., 2004). Due to the internal architecture of the fault zone, shear lenses of post-orogenic sediments of Miocene and Pliocene age including marls and sandstones sequences are juxtaposed to the predominant slaty gouges of the Alpine basement. Microcataclasites and gouges of the quartz-rich post-orogenic sediments are also developed as cm- to m-scale bands, allowing the comparison between the deformed materials and their protoliths. Red, yellow and white sandstones and their respective cataclasites can be identified. This communication is concerned with the clay mineral crystallization events in these materials and its possible influence on the seismicity model of the region. The presence of phyllosilicates in fault zones as either neoformed or inherited clays is commonly related with fluid circulation and a mechanically weak fault behaviour (e.g., Wang, 1984). A critical factor for the understanding of the mechanical role of clays in fault rocks is to determine the timing of formation of mineral assemblages and microstructure of fault rocks and protolith. The effects of post-faulting alteration limit inferences about fault behaviour that can be made from exhumed rocks. The Carboneras fault zone provides good opportunities to study mineral processes enhanced by deformation, given that it is located in a region of arid climate and shows outcroppings of quartzitic rocks included in slaty rocks. Combined XRD, optical microscopy and SEM analyses reveal that deformed quartzitic rocks are enriched in phyllosilicates, increasing especially the amount of chlorite. The samples strongly damaged

Pore water colloid properties in argillaceous sedimentary rocks.

PubMed

Degueldre, Claude; Cloet, Veerle

2016-11-01

The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

Consequences of the Thermal Transient on the Evolution of the Damaged Zone Around a Repository for Heat-Emitting High-Level Radioactive Waste in a Clay Formation: a Performance Assessment Perspective

NASA Astrophysics Data System (ADS)

Yu, Li; Weetjens, Eef; Sillen, Xavier; Vietor, Tim; Li, Xiangling; Delage, Pierre; Labiouse, Vincent; Charlier, Robert

2014-01-01

A proper evaluation of the perturbations of the host rock induced by the excavation and the emplacement of exothermic wastes is essential for the assessment of the long-term safety of high-level radioactive waste disposals in clay formations. The impact of the thermal transient on the evolution of the damaged zone (DZ) has been explored in the European Commission project TIMODAZ (thermal impact on the damaged zone around a radioactive waste disposal in clay host rocks, 2006-2010). This paper integrates the scientific results of the TIMODAZ project from a performance assessment (PA) point of view, showing how these results support and justify key PA assumptions and the values of PA model parameters. This paper also contextualises the significance of the thermal impact on the DZ from a safety case perspective, highlighting how the project outcomes result into an improved understanding of the thermo-hydro-mechanical behaviour of the clay host rocks. The results obtained in the TIMODAZ project strengthen the assessment basis of the safety evaluation of the current repository designs. There was no evidence throughout the TIMODAZ experimental observations of a temperature-induced additional opening of fractures nor of a significant permeability increase of the DZ. Instead, thermally induced plasticity, swelling and creep seem to be beneficial to the sealing of fractures and to the recovery of a very low permeability in the DZ, close to that of an undisturbed clay host rock. Results from the TIMODAZ project indicate that the favourable properties of the clay host rock, which guarantee the effectiveness of the safety functions of the repository system, are expected to be maintained after the heating-cooling cycle. Hence, the basic assumptions usually made in PA calculations so far are expected to remain valid, and the performance of the system should not be affected in a negative way by the thermal evolution of the DZ around a radioactive waste repository in clay host rock.

Hydromechanical modeling of clay rock including fracture damage

NASA Astrophysics Data System (ADS)

Asahina, D.; Houseworth, J. E.; Birkholzer, J. T.

2012-12-01

Argillaceous rock typically acts as a flow barrier, but under certain conditions significant and potentially conductive fractures may be present. Fracture formation is well-known to occur in the vicinity of underground excavations in a region known as the excavation disturbed zone. Such problems are of particular importance for low-permeability, mechanically weak rock such as clays and shales because fractures can be relatively transient as a result of fracture self-sealing processes. Perhaps not as well appreciated is the fact that natural fractures can form in argillaceous rock as a result of hydraulic overpressure caused by phenomena such as disequlibrium compaction, changes in tectonic stress, and mineral dehydration. Overpressure conditions can cause hydraulic fracturing if the fluid pressure leads to tensile effective stresses that exceed the tensile strength of the material. Quantitative modeling of this type of process requires coupling between hydrogeologic processes and geomechanical processes including fracture initiation and propagation. Here we present a computational method for three-dimensional, hydromechanical coupled processes including fracture damage. Fractures are represented as discrete features in a fracture network that interact with a porous rock matrix. Fracture configurations are mapped onto an unstructured, three-dimensonal, Voronoi grid, which is based on a random set of spatial points. Discrete fracture networks (DFN) are represented by the connections of the edges of a Voronoi cells. This methodology has the advantage that fractures can be more easily introduced in response to coupled hydro-mechanical processes and generally eliminates several potential issues associated with the geometry of DFN and numerical gridding. A geomechanical and fracture-damage model is developed here using the Rigid-Body-Spring-Network (RBSN) numerical method. The hydrogelogic and geomechanical models share the same geometrical information from a 3D Voronoi

Excavation Induced Hydraulic Response of Opalinus Clay - Investigations of the FE-Experiment at the Mont Terri URL in Switzerland

NASA Astrophysics Data System (ADS)

Vogt, T.; Müller, H. R.; Garitte, B.; Sakaki, T.; Vietor, T.

2013-12-01

The Full-Scale Emplacement (FE) Experiment at the Mont Terri underground research laboratory in Switzerland is a full-scale heater test in a clay-rich formation (Opalinus Clay). Based on the Swiss disposal concept it simulates the construction, emplacement, backfilling, and post-closure thermo-hydro-mechanical (THM) evolution of a spent fuel / vitrified high-level waste (SF / HLW) repository tunnel in a realistic manner. The main aim of this experiment is to investigate SF / HLW repository-induced THM coupled effects mainly in the host rock but also in the engineered barrier system (EBS), which consists of bentonite pellets and blocks. A further aim is to gather experience with full-scale tunnel construction and associated hydro-mechanical (HM) processes in the host rock. The entire experiment implementation (in a 50 m long gallery with approx. 3 m diameter) as well as the post-closure THM evolution will be monitored using a network of several hundred sensors (state-of-the-art sensors and measurement systems as well as fiber-optic sensors). The sensors are distributed in the host rock's near- and far-field, the tunnel lining, the EBS, and on the heaters. The heater emplacement and backfilling has not started yet, therefore only the host rock instrumentation is installed at the moment and is currently generating data. We will present the instrumentation concept and rationale as well as the first monitoring results of the excavation and ventilation phase. In particular, we investigated the excavation induced hydraulic response of the host rock. Therefore, the spatiotemporal evolution of porewater-pressure time series was analyzed to get a better understanding of HM coupled processes during and after the excavation phase as well as the impact of anisotropic geomechanic and hydraulic properties of the clay-rich formation on its hydraulic behavior. Excavation related investigations were completed by means of inclinometer data to characterize the non-elastic and time

Evaluation of used fuel disposition in clay-bearing rock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jove-Colon, Carlos F.; Hammond, Glenn Edward; Kuhlman, Kristopher L.

The R&D program from the DOE Used Fuel Disposition Campaign (UFDC) has documented key advances in coupled Thermal-Hydrological-Mechanical-Chemical (THMC) modeling of clay to simulate its complex dynamic behavior in response to thermal and hydrochemical feedbacks. These efforts have been harnessed to assess the isolation performance of heat-generating nuclear waste in a deep geological repository in clay/shale/argillaceous rock formations. This report describes the ongoing disposal R&D efforts on the advancement and refinement of coupled THMC process models, hydrothermal experiments on barrier clay interactions, used fuel and canister material degradation, thermodynamic database development, and reactive transport modeling of the near-field under non-isothermalmore » conditions. These play an important role to the evaluation of sacrificial zones as part of the EBS exposure to thermally-driven chemical and transport processes. Thermal inducement of chemical interactions at EBS domains enhances mineral dissolution/precipitation but also generates mineralogical changes that result in mineral H2O uptake/removal (hydration/dehydration reactions). These processes can result in volume changes that can affect the interface / bulk phase porosities and the mechanical (stress) state of the bentonite barrier. Characterization studies on bentonite barrier samples from the FEBEX-DP international activity have provided important insight on clay barrier microstructures (e.g., microcracks) and interactions at EBS interfaces. Enhancements to the used fuel degradation model outlines the need to include the effects of canister corrosion due the strong influence of H2 generation on the source term.« less

Diffusive transport and reaction in clay rocks: A storage (nuclear waste, CO2, H2), energy (shale gas) and water quality issue

NASA Astrophysics Data System (ADS)

Charlet, Laurent; Alt-Epping, Peter; Wersin, Paul; Gilbert, Benjamin

2017-08-01

Clay rocks are low permeability sedimentary formations that provide records of Earth history, influence the quality of water resources, and that are increasingly used for the extraction or storage of energy resources and the sequestration of waste materials. Informed use of clay rock formations to achieve low-carbon or carbon-free energy goals requires the ability to predict the rates of diffusive transport processes for chemically diverse dissolved and gaseous species over periods up to thousands of years. We survey the composition, properties and uses of clay rock and summarize fundamental science challenges in developing confident conceptual and quantitative gas and solute transport models.

Chemical remagnetization and clay diagenesis: testing the hypothesis in the Cretaceous sedimentary rocks of northwestern Montana

NASA Astrophysics Data System (ADS)

Gill, J. D.; Elmore, R. D.; Engel, M. H.

Although the migration of fluids is a likely agent of remagnetization for some chemical remanent magnetizations (CRMs), widespread CRMs, which occur in rocks that have not been altered by externally derived fluids, need to explained by another mechanism. We are testing clay diagenesis as a remagnetization mechanism for such CRMs by comparing results from Mesozoic strata in the disturbed belt of Montana where the rocks contain ordered illite/smectite that formed by moderate heating as a result of thrust loading, with equivalent strata on the adjacent Sweetgrass Arch which contain unaltered smectite-rich clay mineral assemblages. The results indicate that the magnetization in the rocks in the Sweetgrass Arch is weak and dominated by a modern viscous component. In contrast, the disturbed belt rocks have higher magnetic intensities and contain a prefolding or early synfolding, reversed tertiary magnetization that is interpreted to be a CRM residing in magnetite and perhaps pyrrhotite. A presence-absence test and the timing of acquisition for the CRM suggest that magnetite authigenesis could be related to the smectite-to-illite conversion.

Modeling of Coupled Thermo-Hydro-Mechanical-Chemical Processes for Bentonite in a Clay-rock Repository for Heat-generating Nuclear Waste

NASA Astrophysics Data System (ADS)

Xu, H.; Rutqvist, J.; Zheng, L.; Birkholzer, J. T.

2016-12-01

Engineered Barrier Systems (EBS) that include a bentonite-based buffer are designed to isolate the high-level radioactive waste emplaced in tunnels in deep geological formations. The heat emanated from the waste can drive the moisture flow transport and induce strongly coupled Thermal (T), Hydrological (H), Mechanical (M) and Chemical (C) processes within the bentonite buffer and may also impact the evolution of the excavation disturbed zone and the sealing between the buffer and walls of an emplacement tunnel The flow and contaminant transport potential along the disturbed zone can be minimized by backfilling the tunnels with bentonite, if it provides enough swelling stress when hydrated by the host rock. The swelling capability of clay minerals within the bentonite is important for sealing gaps between bentonite block, and between the EBS and the surrounding host rock. However, a high temperature could result in chemical alteration of bentonite-based buffer and backfill materials through illitization, which may compromise the function of these EBS components by reducing their plasticity and capability to swell under wetting. Therefore, an adequate THMC coupling scheme is required to understand and to predict the changes of bentonite for identifying whether EBS bentonite can sustain higher temperatures. More comprehensive links between chemistry and mechanics, taking advantage of the framework provided by a dual-structure model, named Barcelona Expansive Model (BExM), was implemented in TOUGHREACT-FLAC3D and is used to simulate the response of EBS bentonite in in clay formation for a generic case. The current work is to evaluate the chemical changes in EBS bentonite and the effects on the bentonite swelling stress under high temperature. This work sheds light on the interaction between THMC processes, evaluates the potential deterioration of EBS bentonite and supports the decision making in the design of a nuclear waste repository in light of the maximum allowance

Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors—Air Gap Effect

PubMed Central

Bore, Thierry; Wagner, Norman; Delepine Lesoille, Sylvie; Taillade, Frederic; Six, Gonzague; Daout, Franck; Placko, Dominique

2016-01-01

Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling. PMID:27096865

Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors--Air Gap Effect.

PubMed

Bore, Thierry; Wagner, Norman; Lesoille, Sylvie Delepine; Taillade, Frederic; Six, Gonzague; Daout, Franck; Placko, Dominique

2016-04-18

Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling.

Phosphates in some Missouri refractory clays

USGS Publications Warehouse

Halley, Robert B.; Foord, Eugene E.; Keller, David J.; Keller, Walter D.

1997-01-01

This paper describes in detail phosphate minerals occurring in refractory clays of Missouri and their effect on the refractory degree of the clays. The minerals identified include carbonate-fluorapatite (francolite), crandallite, goyazite, wavellite, variscite and strengite. It is emphasized that these phosphates occur only in local isolated concentrations, and not generally in Missouri refractory clays.The Missouri fireclay region comprises 2 districts, northern and southern, separated by the Missouri River. In this region, clay constitutes a major part of the Lower Pennsylvanian Cheltenham Formation. The original Cheltenham mud was an argillic residue derived from leaching and dissolution of pre-Pennsylvanian carbonates. The mud accumulated on a karstic erosion surface truncating the pre-Cheltenham rocks. Fireclays of the northern district consist mainly of poorly ordered kaolinite, with variable but minor amounts of illite, chlorite and fine-grained detrital quartz. Clays of the southern district were subjected to extreme leaching that produced well-ordered kaolinite flint clays. Local desilication formed pockets of diaspore, or more commonly, kaolinite, with oolite-like nubs or burls of diaspore (“burley”" clay).The phosphate-bearing materials have been studied by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectral analysis (SEM-EDS) and chemical analysis. Calcian goyazite was identified in a sample of diaspore, and francolite in a sample of flint clay. A veinlet of wavellite occurs in flint clay at one locality, and a veinlet of variscite-strengite at another locality.The Missouri flint-clay-hosted francolite could not have formed in the same manner as marine francolite. The evidence suggests that the Cheltenham francolite precipitated from ion complexes in pore water, nearly simultaneously with crystallization of kaolinite flint clay from an alumina-silica gel. Calcian goyazite is an early diagenetic addition to its diaspore

Coupled THMC models for bentonite in clay repository for nuclear waste

NASA Astrophysics Data System (ADS)

Zheng, L.; Rutqvist, J.; Birkholzer, J. T.; Li, Y.; Anguiano, H. H.

2015-12-01

Illitization, the transformation of smectite to illite, could compromise some beneficiary features of an engineered barrier system (EBS) that is composed primarily of bentonite and clay host rock. It is a major determining factor to establish the maximum design temperature of the repositories because it is believed that illitization could be greatly enhanced at temperatures higher than 100 oC and thus significantly lower the sorption and swelling capacity of bentonite and clay rock. However, existing experimental and modeling studies on the occurrence of illitization and related performance impacts are not conclusive, in part because the relevant couplings between the thermal, hydrological, chemical, and mechanical (THMC) processes have not been fully represented in the models. Here we present fully coupled THMC simulations of a generic nuclear waste repository in a clay formation with bentonite-backfilled EBS. Two scenarios were simulated for comparison: a case in which the temperature in the bentonite near the waste canister can reach about 200 oC and a case in which the temperature in the bentonite near the waste canister peaks at about 100 oC. The model simulations demonstrate that illitization is in general more significant at higher temperatures. We also compared the chemical changes and the resulting swelling stress change for two types of bentonite: Kunigel-VI and FEBEX bentonite. Higher temperatures also lead to much higher stress in the near field, caused by thermal pressurization and vapor pressure buildup in the EBS bentonite and clay host rock. Chemical changes lead to a reduction in swelling stress, which is more pronounced for Kunigel-VI bentonite than for FEBEX bentonite.

Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

NASA Astrophysics Data System (ADS)

Laurich, Ben; Urai, Janos L.; Vollmer, Christian; Nussbaum, Christophe

2018-01-01

We studied gouge from an upper-crustal, low-offset reverse fault in slightly overconsolidated claystone in the Mont Terri rock laboratory (Switzerland). The laboratory is designed to evaluate the suitability of the Opalinus Clay formation (OPA) to host a repository for radioactive waste. The gouge occurs in thin bands and lenses in the fault zone; it is darker in color and less fissile than the surrounding rock. It shows a matrix-based, P-foliated microfabric bordered and truncated by micrometer-thin shear zones consisting of aligned clay grains, as shown with broad-ion-beam scanning electron microscopy (BIB-SEM) and optical microscopy. Selected area electron diffraction based on transmission electron microscopy (TEM) shows evidence for randomly oriented nanometer-sized clay particles in the gouge matrix, surrounding larger elongated phyllosilicates with a strict P foliation. For the first time for the OPA, we report the occurrence of amorphous SiO2 grains within the gouge. Gouge has lower SEM-visible porosity and almost no calcite grains compared to the undeformed OPA. We present two hypotheses to explain the origin of gouge in the Main Fault: (i) authigenic generation consisting of fluid-mediated removal of calcite from the deforming OPA during shearing and (ii) clay smear consisting of mechanical smearing of calcite-poor (yet to be identified) source layers into the fault zone. Based on our data we prefer the first or a combination of both, but more work is needed to resolve this. Microstructures indicate a range of deformation mechanisms including solution-precipitation processes and a gouge that is weaker than the OPA because of the lower fraction of hard grains. For gouge, we infer a more rate-dependent frictional rheology than suggested from laboratory experiments on the undeformed OPA.

Mont Terri Underground Rock Laboratory, Switzerland-Research Program And Key Results

NASA Astrophysics Data System (ADS)

Nussbaum, C. O.; Bossart, P. J.

2012-12-01

Argillaceous formations generally act as aquitards because of their low hydraulic conductivities. This property, together with the large retention capacity of clays for cationic contaminants and the potential for self-sealing, has brought clay formations into focus as potential host rocks for the geological disposal of radioactive waste. Excavated in the Opalinus Clay formation, the Mont Terri underground rock laboratory in the Jura Mountains of NW Switzerland is an important international test site for researching clay formations. Research is carried out in the underground facility, which is located adjacent to the security gallery of the Mont Terri motorway tunnel. Fifteen partners from European countries, USA, Canada and Japan participate in the project. The objectives of the research program are to analyze the hydrogeological, geochemical and rock mechanical properties of the Opalinus Clay, to determine the changes induced by the excavation of galleries and by heating of the rock formation, to test sealing and container emplacement techniques and to evaluate and improve suitable investigation techniques. For the safety of deep geological disposal, it is of key importance to understand the processes occurring in the undisturbed argillaceous environment, as well as the processes in a disturbed system, during the operation of the repository. The objectives are related to: 1. Understanding processes and mechanisms in undisturbed clays and 2. Experiments related to repository-induced perturbations. Experiments of the first group are dedicated to: i) Improvement of drilling and excavation technologies and sampling methods; ii) Estimation of hydrogeological, rock mechanical and geochemical parameters of the undisturbed Opalinus Clay. Upscaling of parameters from laboratory to in situ scale; iii) Geochemistry of porewater and natural gases; evolution of porewater over time scales; iv) Assessment of long-term hydraulic transients associated with erosion and thermal

Effect of confining pressure on diffusion coefficients in clay-rich, low-permeability sedimentary rocks.

PubMed

Xiang, Y; Al, T; Mazurek, M

2016-12-01

The effect of confining pressure (CP) on the diffusion of tritiated-water (HTO) and iodide (I - ) tracers through Ordovician rocks from the Michigan Basin, southwestern Ontario, Canada, and Opalinus Clay from Schlattingen, Switzerland was investigated in laboratory experiments. Four samples representing different formations and lithologies in the Michigan Basin were studied: Queenston Formation shale, Georgian Bay Formation shale, Cobourg Formation limestone and Cobourg Formation argillaceous limestone. Estimated in situ vertical stresses at the depths from which the samples were retrieved range from 12.0 to 17.4MPa (Michigan Basin) and from 21 to 23MPa (Opalinus Clay). Effective diffusion coefficients (D e ) were determined in through-diffusion experiments. With HTO tracer, applying CP resulted in decreases in D e of 12.5% for the Queenston Formation shale (CP max =12MPa), 30% for the Georgian Bay Formation shale (15MPa), 34% for the Cobourg Formation limestone (17.4MPa), 31% for the Cobourg Formation argillaceous limestone (17.4MPa) and 43-46% for the Opalinus Clay (15MPa). Decreases in D e were larger for the I - tracer: 13.8% for the Queenston shale, 42% for the Georgian Bay shale, 50% for the Cobourg Formation limestone, 55% for the Cobourg Formation argillaceous limestone and 63-68% for the Opalinus Clay. The tracer-specific nature of the response is attributed to an increasing influence of anion exclusion as the pore size decreases at higher CP. Results from the shales (including Opalinus Clay) indicate that the pressure effect on D e can be represented by a linear relationship between D e and ln(CP), which provides valuable predictive capability. The nonlinearity results in a relatively small change in D e at high CP, suggesting that it is not necessary to apply the exact in situ pressure conditions in order to obtain a good estimate of the in situ diffusion coefficient. Most importantly, the CP effect on shale is reversible (±12%) suggesting that, for

Monitoring water content in Opalinus Clay within the FE-Experiment: Test application of dielectric water content sensors

NASA Astrophysics Data System (ADS)

Sakaki, T.; Vogt, T.; Komatsu, M.; Müller, H. R.

2013-12-01

The spatiotemporal variation of water content in the near field rock around repository tunnels for radioactive waste in clay formations is one of the essential quantities to be monitored for safety assessment in many waste disposal programs. Reliable measurements of water content are important not only for the understanding and prediction of coupled hydraulic-mechanic processes that occur during tunnel construction and ventilation phase, but also for the understanding of coupled thermal-hydraulic-mechanical (THM) processes that take place in the host rock during the post closure phase of a repository tunnel for spent fuel and high level radioactive waste (SF/HLW). The host rock of the Swiss disposal concept for SF/HLW is the Opalinus Clay formation (age of approx. 175 Million years). To better understand the THM effects in a full-scale heater-engineered barrier-rock system in Opalinus Clay, a full-scale heater test, namely the Full-Scale Emplacement (FE) experiment, was initiated in 2010 at the Mont Terri underground rock laboratory in north-western Switzerland. The experiment is designed to simulate the THM evolution of a SF/HLW repository tunnel based on the Swiss disposal concept in a realistic manner during the construction, emplacement, backfilling, and post-closure phases. The entire experiment implementation (in a 50 m long gallery with approx. 3 m diameter) as well as the post-closure THM evolution will be monitored using a network of several hundred sensors. The sensors will be distributed in the host rock, the tunnel lining, the engineered barrier, which consists of bentonite pellets and blocks, and on the heaters. The excavation is completed and the tunnel is currently being ventilated. Measuring water content in partially saturated clay-rich high-salinity rock with a deformable grain skeleton is challenging. Therefore, we use the ventilation phase (before backfilling and heating) to examine the applicability of commercial water content sensors and to

The effect of clay on the dissolution of nuclear waste glass

NASA Astrophysics Data System (ADS)

Lemmens, K.

2001-09-01

In a nuclear waste repository, the waste glass can interact with metals, backfill materials (if present) and natural host rock. Of the various host rocks considered, clays are often reported to delay the onset of the apparent glass saturation, where the glass dissolution rate becomes very small. This effect is ascribed to the sorption of silica or other glass components on the clay. This can have two consequences: (1) the decrease of the silica concentration in solution increases the driving force for further dissolution of glass silica, and (2) the transfer of relatively insoluble glass components (mainly silica) from the glass surface to the clay makes the alteration layer less protective. In recent literature, the latter explanation has gained credibility. The impact of the environmental materials on the glass surface layers is however not well understood. Although the glass dissolution can initially be enhanced by clay, there are arguments to assume that it will decrease to very low values after a long time. Whether this will indeed be the case, depends on the fate of the released glass components in the clay. If they are sorbed on specific sites, it is likely that saturation of the clay will occur. If however the released glass components are removed by precipitation (growth of pre-existing or new secondary phases), saturation of the clay is less likely, and the process can continue until exhaustion of one of the system components. There are indications that the latter mechanism can occur for varying glass compositions in Boom Clay and FoCa clay. If sorption or precipitation prevents the formation of protective surface layers, the glass dissolution can in principle proceed at a high rate. High silica concentrations are assumed to decrease the dissolution rate (by a solution saturation effect or by the impact on the properties of the glass alteration layer). In glass corrosion tests at high clay concentrations, silica concentrations are, however, often higher

Evaluation of frictional melting on the basis of trace element analyses of fault rocks

NASA Astrophysics Data System (ADS)

Ishikawa, T.; Ujiie, K.

2016-12-01

Pseudotachylytes (solidified frictional melts produced during seismic slip) found in exhumed accretionary complexes are considered to have formed originally at seismogenic depths, and help our understanding of the dynamics of earthquake faulting in subduction zones. The frictional melting should affect rock chemistry. Actually, major element compositions of unaltered pseudotachylyte matrix in the Shimanto accretionary complex are reported to be similar to that of illite, implying disequilibrium melting in the slip zone (Ujiie et al., 2007). Bulk-rock trace element analyses of the pseudotachylyte-bearing fault rocks also revealed their shift to the clay-mineral-like compositions (Honda et al., 2011). Toward better understanding of the frictional melting using chemical means, we carried out detailed major and trace element analyses for pseudotachylyte-bearing dark veins and surrounding host rocks from the Mugi area of the Shimanto accretionary complex (Ujiie et al., 2007). About one milligram each of samples was collected from a rock chip along the microstructure by using the PC-controlled micro-drilling apparatus, and then analyzed by ICP-MS. Host rocks showed a series of compositional trends controlled by mixing of detrital sedimentary components. Unaltered part of the pseudotachylyte vein, on the other hand, showed striking enrichment of fluid-immobile trace elements, consistent with selective melting of fine-grained, clay-rich matrix of the fault rock. Importantly, completely altered parts of the dark veins exhibit essentially the same characteristics as the unaltered part, indicating that the trace element composition of the pseudotachylyte is well preserved even after considerable alteration in the later stages. These results demonstrate that trace element and structural analyses are useful to detect preexistence of pseudotachylytes resulting from selective frictional melting of clay minerals. It has been controversial that pseudotachylytes are rarely formed or

Clay Mineral Structure Similar to Clays Observed in Mudstone on Mars

NASA Image and Video Library

2013-12-09

This schematic shows the atomic structure of the smallest units that make up the layers and interlayer region of clay minerals. This structure is similar to the clay mineral in drilled rock powder collected by NASA Curiosity Mars rover.

Geology, Geochemistry and Geophysics of Sedimentary Rock-Hosted Au Deposits in P.R. China

USGS Publications Warehouse

Peters, Stephen G.

2002-01-01

This is the second report concerning results of a joint project between the U.S. Geological Survey and the Tianjin Geological Academy to study sedimentary rock-hosted Au deposits in P.R. China. Since the 1980s, Chinese geologists have devoted a large-scale exploration and research effort to the deposits. As a result, there are more than 20 million oz of proven Au reserves in sedimentary rock-hosted Au deposits in P.R. China. Additional estimated and inferred resources are present in over 160 deposits and occurrences, which are undergoing exploration. This makes China second to Nevada in contained ounces of Au in Carlin-type deposits. It is likely that many of the Carlin-type Au ore districts in China, when fully developed, could have resource potential comparable to the multi-1,000-tonne Au resource in northern Nevada. The six chapters of this report describe sedimentary rock-hosted Au deposits that were visited during the project. Chapters 1 and 2 provide an overview of sedimentary rock-hosted Au deposits and Carlin-type Au deposits and also provide a working classification for the sedimentary rock-hosted Au deposits. Chapters 3, 4, and 5 provide descriptions that were compiled from the literature in China in three main areas: the Dian-Qian-Gui, the Qinling fold belt, and Middle-Lower Yangtze River areas. Chapter 6 contains a weights-of-evidence (WofE), GIS-based mineral assessment of sedimentary rock-hosted Au deposits in the Qinling fold belt and Dian-Qian-Gui areas. Appendices contain scanned aeromagnetic (Appendix I) and gravity (Appendix II) geophysical maps of south and central China. Data tables of the deposits (Appendix III) also are available in the first report as an interactive database at http://geopubs.wr.usgs.gov/open-file/of98-466/. Geochemical analysis of ore samples from the deposits visited are contained in Appendix IV.

Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange

As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents themore » distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository

Clay at Nili Fossae

NASA Technical Reports Server (NTRS)

2006-01-01

This image of the Nili Fossae region of Mars was compiled from separate images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the High-Resolution Imaging Science Experiment (HiRISE), two instruments on NASA's Mars Reconnaissance Orbiter. The images were taken at 0730 UTC (2:30 a.m. EDT) on Oct. 4, 2006, near 20.4 degrees north latitude, 78.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36 to 3.92 micrometers, and shows features as small as 18 meters (60 feet) across. HiRISE's image was taken in three colors, but its much higher resolution shows features as small as 30 centimeters (1 foot) across.

CRISM's sister instrument on the Mars Express spacecraft, OMEGA, discovered that some of the most ancient regions of Mars are rich in clay minerals, formed when water altered the planet's volcanic rocks. From the OMEGA data it was unclear whether the clays formed at the surface during Mars' earliest history of if they formed at depth and were later exposed by impact craters or erosion of the overlying rocks. Clays are an indicator of wet, benign environments possibly suitable for biological processes, making Nili Fossae and comparable regions important targets for both CRISM and HiRISE.

In this visualization of the combined data from the two instruments, the CRISM data were used to calculate the strengths of spectral absorption bands due to minerals present in the scene. The two major minerals detected by the instrument are olivine, a mineral characteristic of primitive igneous rocks, and clay. Areas rich in olivine are shown in red, and minerals rich in clay are shown in green. The derived colors were then overlayed on the HiRISE image.

The area where the CRISM and HiRISE data overlap is shown at the upper left, and is about 5 kilometers (3 miles) across. The three boxes outlined in blue are enlarged to show how the different minerals in the scene match up with different landforms. In the image

Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks

NASA Astrophysics Data System (ADS)

Butscher, Christoph; Einstein, Herbert H.; Huggenberger, Peter

2011-11-01

Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel excavation. The present study investigates the hydraulic effects of tunneling on groundwater flow and analyzes how hydraulic changes caused by excavation lead to water inflow into anhydrite-containing layers in the tunnel area. Numerical groundwater models are used to conduct scenario simulations that allow one to relate hydrogeological conditions to rock swelling. The influence of the topographic setting, the excavation-damaged zone around the tunnel, the sealing effect of the tunnel liner, and the geological configuration are analyzed separately. The analysis is performed for synthetic situations and is complemented by a case study from a tunnel in Switzerland. The results illustrate the importance of geological and hydraulic information when assessing the risk of swelling at an actual site.

Constraints for estimating the future burial depth of host rocks for geological waste disposal: a case study from the Boom Clay, Campine area, Northern Belgium

NASA Astrophysics Data System (ADS)

Beerten, K.; De Craen, M.; Brassinnes, S.

2012-04-01

An important requirement for geological formations hosting a repository for radioactive waste is sufficient depth to ensure isolation of the waste for a very long time period, up to 1 Ma and beyond. Over such long timescales, the repository depth and the thickness of the overburden may vary significantly due to various geodynamic processes. In Belgium, the Boom Clay in the Campine area (NE-Belgium) is considered as reference host formation for the geological disposal of radioactive waste. First results are presented that illustrate the possible impact of future climate change (based on several scenarios studied in the BIOCLIM project (BIOCLIM, 2001)) and tectonic movements in the Campine area on the thickness of the sediment mass overlying the Boom Clay. At present, the subcrop area of Boom Clay in the Campine area is relatively flat (between ~ 0 m a.s.l. near the river Scheldt estuary in the west and ~ 60 m a.s.l. on the Campine Plateau in the east) and is occupied by several sub-basins that belong to the rivers Meuse and Scheldt. Future development of the area will heavily depend on the behaviour of these rivers and tributaries throughout the considered timeframe, in response to climatic changes and tectonic movements. The area is characterised by a long burial history, with some minor isolated uplift and erosional events during the last 30 Ma. In a global warming scenario during a long interglacial (> 50 ka AP), and/or in the case of subsidence, (relative) sea-level may rise such that various parts of the Boom Clay area will be occupied by the marine realm. This is likely to be a minimal erosion scenario because the baseline for landscape evolution will rise in the upstream parts while estuarine and marine deposition may increase the thickness of the overburden in the downstream parts. In the case of a continuation of Pleistocene glacial cycles, i.e. the alternation between warm interglacials and cold glacials, the area will be exposed to erosion and denudation

Characterizing Fracturing of Clay-Rich Lower Watrous Rock: From Laboratory Experiments to Nonlocal Damage-Based Simulations

NASA Astrophysics Data System (ADS)

Guy, N.; Seyedi, D. M.; Hild, F.

2018-06-01

The work presented herein aims at characterizing and modeling fracturing (i.e., initiation and propagation of cracks) in a clay-rich rock. The analysis is based on two experimental campaigns. The first one relies on a probabilistic analysis of crack initiation considering Brazilian and three-point flexural tests. The second one involves digital image correlation to characterize crack propagation. A nonlocal damage model based on stress regularization is used for the simulations. Two thresholds both based on regularized stress fields are considered. They are determined from the experimental campaigns performed on Lower Watrous rock. The results obtained with the proposed approach are favorably compared with the experimental results.

Organic tissues, graphite, and hydrocarbons in host rocks of the Rum Jungle Uranium Field, northern Australia

USGS Publications Warehouse

Foster, C.B.; Robbins, E.I.; Bone, Y.

1990-01-01

The Rum Jungle Uranium field consists of at least six early Proterozoic deposits that have been mined either for uranium and/or the associated base and precious metals. Organic matter in the host rocks of the Whites Formation and Coomalie Dolomite is now predominantly graphite, consistent with the metamorphic history of these rocks. For nine samples, the mean total organic carbon content is high (3.9 wt%) and ranged from 0.33 to 10.44 wt%. Palynological extracts from the host rocks include black, filamentous, stellate (Eoastrion-like), and spherical morphotypes, which are typical of early Proterozoic microbiota. The colour, abundance, and shapes of these morphotypes reflect the thermal history, organic richness, and probable lacustrine biofacies of the host rocks. Routine analysis of rock thin sections and of palynological residues shows that mineral grains in some of the host rocks are coated with graphitized organic matter. The grain coating is presumed to result from ultimate thermal degradation of a petroleum phase that existed prior to metamorphism. Hydrocarbons are, however, still present in fluid inclusions within carbonates of the Coomalie Dolomite and lower Whites Formation. The fluid inclusions fluoresce dull orange in blue-light excitation and their hydrocarbon content is confirmed by gas chromatography of whole-rock extracts. Preliminary analysis of the oil suggests that it is migrated, and because it has escaped graphitization through metamorphism it is probably not of early Proterozoic age. The presence of live oil is consistent with fluid inclusion data that suggest subsequent, low-temperature brine migration through the rocks. The present observations support earlier suggestions that organic matter in the host formations trapped uranium to form protore. Subsequent fluid migrations probably brought additional uranium and other metals to these formations, and the organic matter provided a reducing environment for entrapment. ?? 1990.

Frictional processes during flank motion at Mount Etna (Italy): experimental characterisation of slip on similar and dissimilar volcanic and sedimentary rocks.

NASA Astrophysics Data System (ADS)

Rozanski, Wojciech; Lavallee, Yan; Kendrick, Jackie; Castagna, Angela; Mitchell, Thomas; Heap, Michael; Vinciguerra, Sergio; Hirose, Takehiro; Dingwell, Donald

2015-04-01

The edifice of Mount Etna (Italy) is structurally unstable, exhibiting a near continuous ESE seaward sliding along a set of faults due to interplay between regional tectonics, gravity instability and magma intrusion. Continuous seismic and ground deformation monitoring reveals the resulting large-scale flank motion at variable rates. The mechanisms controlling this faulting kinetic remains, however, poorly constrained. Examination of the fault zones reveals a range of rock types along the different fault segments: fresh and altered basalt, clay and limestone. As lithological contrasts can jeopardise the structural stability of an edifice, we experimentally investigate the frictional properties of these rocks using low- to high-velocity-rotary shear tests on similar and dissimilar rocks to better understand episodes of slow flank motion as well as rapid and catastrophic sector collapse events. The first set of experiments was performed at velocities up to 1.2 m/s and at normal stresses of 1.5 MPa, commensurate with depths of the contacts seen in the Etna edifice. Friction experiments on clay gouge shows the strong rate-weakening dependence of slip in this material as well as the release of carbon dioxide. Friction experiments on solid rocks show a wider range of mechanical behaviour. At high velocity (>0.6 m/s) volcanic rocks tend to melt whereas the clay and limestone do not; rather they decarbonate, which prevents the rock from achieving the temperature required for melting. Experiments on dissimilar rocks clearly show that composition of host rocks affects the composition and viscosity of the resultant frictional melt, which can have a dramatic effect on shear stress leading to fault weakening or strengthening depending on the combination of host rock samples. A series of low- to moderate-slip velocity experiments is now being conducted to complement our dataset and provide a more complete rock friction model applicable to Mount Etna.

Water saturation of hydrothermal smectite-rich clay might have promoted slope instability prior to the 1998 debris avalanche at Casita volcano, Nicaragua

NASA Astrophysics Data System (ADS)

Delmelle, P.; Opfergelt, S.; Boivin, P.; Delvaux, B.

2006-12-01

In October 1998, a relatively small collapse (1 600 000 cubic meters) of a pre-existing scarp occurred on the southern flank of the dormant Casita volcano, Nicaragua. It resulted in a debris avalanche, which quickly transformed into a disastrous debris flow that destroyed two towns and killed more than 2500 people. The failure was shown to be triggered by an excess pore water pressure within highly fractured rocks, following prolonged seasonal rains and precipitations from Hurricane Mitch. This pressure was linked to the water saturation of a hydrothermally-altered clay bedrock impeding in-depth infiltration. Yet, the nature and amounts of the clay material involved in the slope failure were still unknown. Here we report on physical, chemical and mineralogical investigations aimed at quantifying the clay content, and identifying the layer silicates of the hydrothermally-altered clays uncovered by the 1998 debris avalanche. The fine clay material was exceptionally rich in smectite (up to 50 wt. percent), which swells upon wetting and shrinks during dry conditions (Opfergelt et al., 2006, Geophys. Res. Lett., 33 (15), L15305). The smectite belonged to the beidellite-montmorillonite series. The pervasive presence of water-saturated smectitic clay strongly reduced the permeability in depth, and also altered the rheological and mechanical properties of both the pre-failure rock mass and flow materials. The shrink-swell behavior progressively decreased the rock's shear strength, and gradually destabilized the overlying rock mass in the decades and centuries before the landslide, thereby contributing to slope instability. Prolonged intense rainfall led to the formation of incipient weak failure surfaces in the superficial rock mass. As provoked by water saturation, this process was likely favored by the rapid change of the mechanical properties of smectite-rich clays deposited in fracture, joint and gouge interfaces. We suggest that hazard assessments associated with

Geological modeling of a fault zone in clay rocks at the Mont-Terri laboratory (Switzerland)

NASA Astrophysics Data System (ADS)

Kakurina, M.; Guglielmi, Y.; Nussbaum, C.; Valley, B.

2016-12-01

Clay-rich formations are considered to be a natural barrier for radionuclides or fluids (water, hydrocarbons, CO2) migration. However, little is known about the architecture of faults affecting clay formations because of their quick alteration at the Earth's surface. The Mont Terri Underground Research Laboratory provides exceptional conditions to investigate an un-weathered, perfectly exposed clay fault zone architecture and to conduct fault activation experiments that allow explore the conditions for stability of such clay faults. Here we show first results from a detailed geological model of the Mont Terri Main Fault architecture, using GoCad software, a detailed structural analysis of 6 fully cored and logged 30-to-50m long and 3-to-15m spaced boreholes crossing the fault zone. These high-definition geological data were acquired within the Fault Slip (FS) experiment project that consisted in fluid injections in different intervals within the fault using the SIMFIP probe to explore the conditions for the fault mechanical and seismic stability. The Mont Terri Main Fault "core" consists of a thrust zone about 0.8 to 3m wide that is bounded by two major fault planes. Between these planes, there is an assembly of distinct slickensided surfaces and various facies including scaly clays, fault gouge and fractured zones. Scaly clay including S-C bands and microfolds occurs in larger zones at top and bottom of the Mail Fault. A cm-thin layer of gouge, that is known to accommodate high strain parts, runs along the upper fault zone boundary. The non-scaly part mainly consists of undeformed rock block, bounded by slickensides. Such a complexity as well as the continuity of the two major surfaces are hard to correlate between the different boreholes even with the high density of geological data within the relatively small volume of the experiment. This may show that a poor strain localization occurred during faulting giving some perspectives about the potential for

Preliminary Numerical Simulations of Nozzle Formation in the Host Rock of Supersonic Volcanic Jets

NASA Astrophysics Data System (ADS)

Wohletz, K. H.; Ogden, D. E.; Glatzmaier, G. A.

2006-12-01

Recognizing the difficulty in quantitatively predicting how a vent changes during an explosive eruption, Kieffer (Kieffer, S.W., Rev. Geophys. 27, 1989) developed the theory of fluid dynamic nozzles for volcanism, utilizing a highly developed predictive scheme used extensively in aerodynamics for design of jet and rocket nozzles. Kieffer's work shows that explosive eruptions involve flow from sub to supersonic conditions through the vent and that these conditions control the erosion of the vent to nozzle shapes and sizes that maximize mass flux. The question remains how to predict the failure and erosion of vent host rocks by a high-speed, multiphase, compressible fluid that represents an eruption column. Clearly, in order to have a quantitative model of vent dynamics one needs a robust computational method for a turbulent, compressible, multiphase fluid. Here we present preliminary simulations of fluid flowing from a high-pressure reservoir through an eroding conduit and into the atmosphere. The eruptive fluid is modeled as an ideal gas, the host rock as a simple incompressible fluid with sandstone properties. Although these simulations do not yet include the multiphase dynamics of the eruptive fluid or the solid mechanics of the host rock, the evolution of the host rock into a supersonic nozzle is clearly seen. Our simulations show shock fronts both above the conduit, where the gas has expanded into the atmosphere, and within the conduit itself, thereby influencing the dynamics of the jet decompression.

Geology and geochemistry of three sedimentary-rock-hosted disseminated gold deposits in Guizhou Province, People's Republic of China

USGS Publications Warehouse

Ashley, R.P.; Cunningham, C.G.; Bostick, N.H.; Dean, W.E.; Chou, I.-Ming

1991-01-01

Five sedimentary-rock-hosted disseminated gold deposits have been discovered since 1980 in southwestern Guizhou Province (PRC). Submicron-sized gold is disseminated in silty carbonate and carbonaceous shale host rocks of Permian and Triassic age. Arsenic, antimony, mercury, and thallium accompany the gold. Associated hydrothermal alteration resulted in decarbonatization of limestone, silicification, and argillization, and depletion of base metals, barium, and many other elements. Organic material occurs in most host rocks and ores. It was apparently devolatilized during a regional heating event that preceded hydrothermal activity, and thus was not mobilized during mineralization, and did not affect gold deposition. The geologic setting of the Guizhou deposits includes many features that are similar to those of sedimentary-rock-hosted deposits of the Great Basin, western United States. The heavy-element suite that accompanies gold is the same, but base metals are even scarcer in the Guizhou deposits than they are in U.S. deposits. The Guizhou deposits discovered to date are smaller than most U.S. deposits and have no known spatially associated igneous rocks. ?? 1991.

Can clays ensure nuclear waste repositories?

NASA Astrophysics Data System (ADS)

Zaoui, A.; Sekkal, W.

2015-03-01

Research on argillite as a possible host rock for nuclear waste disposal is still an open subject since many issues need to be clarified. In the Underground Research Laboratories constructed for this purpose, a damaged zone around the excavation has been systematically observed and characterized by the appearance of micro-fissures. We analyse here -at nanoscale level- the calcite/clay assembly, the main constituents of argillite, under storage conditions and show the fragility of the montmorillonite with respect to calcite. Under anisotropic stress, we have observed a shear deformation of the assembly with the presence of broken bonds in the clay mineral, localised in the octahedral rather than the tetrahedral layers. The stress/strain curve leads to a failure strength point at 18.5 MPa. The obtained in-plane response of the assembly to perpendicular deformation is characterized by smaller perpendicular moduli Ez = 48.28 GPa compared to larger in-plane moduli Ex = 141.39 GPa and Ey = 134.02 GPa. Our calculations indicate the instability of the assembly without water molecules at the interface in addition to an important shear deformation.

Obtaining the porewater composition of a clay rock by modeling the in- and out-diffusion of anions and cations from an in-situ experiment.

PubMed

Appelo, C A J; Vinsot, A; Mettler, S; Wechner, S

2008-10-23

A borehole in the Callovo-Oxfordian clay rock in ANDRA's underground research facility was sampled during 1 year and chemically analyzed. Diffusion between porewater and the borehole solution resulted in concentration changes which were modeled with PHREEQC's multicomponent diffusion module. In the model, the clay rock's pore space is divided in free porewater (electrically neutral) and diffuse double layer water (devoid of anions). Diffusion is calculated separately for the two domains, and individually for all the solute species while a zero-charge flux is maintained. We explain how the finite difference formulas for radial diffusion can be translated into mixing factors for solutions. Operator splitting is used to calculate advective flow and chemical reactions such as ion exchange and calcite dissolution and precipitation. The ion exchange reaction is formulated in the form of surface complexation, which allows distributing charge over the fixed sites and the diffuse double layer. The charge distribution affects pH when calcite dissolves, and modeling of the experimental data shows that about 7% of the cation exchange capacity resides in the diffuse double layer. The model calculates the observed concentration changes very well and provides an estimate of the pristine porewater composition in the clay rock.

Origin and diagenesis of clay minerals in relation to sandstone paragenesis: An example in eolian dune reservoirs and associated rocks, Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pollastro, R.M.; Schenk, C.J.

Eolian dune sandstones are the principal reservoir rocks in the Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming. These sandstones formed as shorelines retreated and dunes migrated across siliciclastic sabkhas. Sandstones are mainly quartzarenites; on average, clay minerals constitute about 5 wt.% the whole rock. Although present in minor amounts, clay minerals play an important role in the diagenetic evolution of these sandstones. Allogenic clay minerals are present in shaly rock fragments and laminae. Early infiltration of clays into porous sabkha sands commonly form characteristic menisei or bridges between framework grains or, when more extensive, form coatingsmore » or rims on grain surfaces. Authigenic clays include nearly pure smectite, mixed-layer illite/smectite (I/S), and late diagenetic illite and corrensite; these clay minerals are present as pore-lining cements. In addition to the deposition and neoformation of clay minerals throughout sandstone paragenesis, the conversion of smectite to illite occurred as temperatures increased with progressive burial. A temperature of 103C is calculated at a present depth of 3,200 m using a geothermal gradient of 30C/km and a mean annual surface temperature of 7C. After correction for uplift and erosion (250 m), the maximum calculated temperature for the conversion of all random I/S to ordered I/S is 100C. This calculated temperature is in excellent agreement with temperatures of 100-110C implied from I/S geothermometry.« less

Use of structural geology in exploration for and mining of sedimentary rock-hosted Au deposits

USGS Publications Warehouse

Peters, Stephen G.

2001-01-01

Structural geology is an important component in regional-, district- and orebody-scale exploration and development of sedimentary rock-hosted Au deposits.Identification of timing of important structural events in an ore district allows analysis and classification of fluid conduits and construction of genetic models for ore formation.The most practical uses of structural geology deal with measurement and definition of various elements that comprise orebodies, which can then be directly applied to ore-reserve estimation,ground control,grade control, safety issues,and mine planning.District- and regional-scale structural studies are directly applicable to long-term strategic planning,economic analysis,and land ownership. Orebodies in sedimentary rock-hosted Au deposits are discrete, hypogene, epigenetic masses usually hosted in a fault zone,breccia mass, or lithologic bed or unit. These attributes allow structural geology to be directly applied to the mining and exploration of sedimentary rock-hosted Au deposits. Internal constituents in orebodies reflect unique episodes relating to ore formation.The main internal constituents in orebodies are ore minerals, gangue, and alteration minerals that usually are mixed with one another in complex patterns, the relations among which may be used to interpret the processes of orebody formation and control.Controls of orebody location and shape usually are due to structural dilatant zones caused by changes in attitude, splays, lithologic contacts,and intersections of the host conduit or unit.In addition,conceptual parameters such as district fabric,predictable distances, and stacking also are used to understand the geometry of orebodies.Controls in ore districts and location and geometry of orebodies in ore districts can be predicted to various degrees by using a number of qualitative concepts such as internal and external orebody plunges,district plunge, district stacking, conduit classification, geochemical, geobarometric and

Contrasting diagenetic histories of concretions vs. host rocks, Lion Mountain Member, Riley formation (upper Cambrian), Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

McBride, E.F.

1988-02-01

White, elliptical, calcite-cemented concretion nuclei up to 1 m long contrast markedly in color, composition, and diagenetic history from more glauconite-rich concretion rinds and from dark-green glaucarenite host rocks. Concretion nuclei are loosely packed deposits of trilobite carapaces and minor quartz and glauconite that have intergranular volumes of 58%. The nuclei are shell-lag deposits that were cemented by calcite at the sea floor or after burial of a few meters. Concretion rinds, composed of subequal amounts of quartz and compactionally deformed glauconite, have an intergranular volume of only 32% and minor quartz overgrowths that preceded pore-occluding calcite cement. The rindsmore » underwent burial for several million years to tens of millions of years to depths of several hundred meters before they were cemented. The host rock is predominately glauconite with very minor quartz and calcite cement. Strontium isotopic ratios of host-rock calcite cement are variable (0.7084 to 0.7093), but the lowest value suggests precipitation during the Middle Ordovician. In the absence of significant amounts of carbonate cement, the host rock underwent complete dissolution of trilobite carapaces and maximum compaction with total loss of porosity through squashing of glauconite grains. Maximum burial during this stage was completed by the end of Ordovician time.« less

[Interaction of clay minerals with microorganisms: a review of experimental data].

PubMed

Naĭmark, E B; Eroshchev-Shak, V A; Chizhikova, N P; Kompantseva, E I

2009-01-01

A review of publications containing results of experiments on the interaction of microorganisms with clay minerals is presented. Bacteria are shown to be involved in all processes related to the transformation of clay minerals: formation of clays from metamorphic and sedimentary rocks, formation of clays from solutions, reversible transitions of different types of clay minerals, and consolidation of clay minerals into sedimentary rocks. Integration of these results allows to conclude that bacteria reproduced all possible abiotic reactions associated with the clay minerals, these reactions proceed much faster with the bacteria being involved. Thus, bacteria act as a living catalyst in the geochemical cycle of clay minerals. The ecological role of bacteria can be considered as a repetition of a chemical process of the abiotic world, but with the use of organic catalytic innovation.

Micro-fabric damages in Boom Clay inferred from cryo-BIB-SEM experiment: recent results

NASA Astrophysics Data System (ADS)

Desbois, Guillaume; Schmatz, Joyce; Klaver, Jop; Urai, Janos L.

2017-04-01

The Boom Clay is considered as a potential host rock in Belgium for nuclear waste disposal in a deep geological formation. One of the keys to understand the long-term performance of such a host rock is the fundamental understanding of coupling between microstructural evolution, poromechanical behaviour and the state of hydration of the system. At in situ conditions, Boom Clay is a nearly water-saturated (>94%) clay-rich geomaterial. Subsequently, for measurement of mechanical and transport properties in laboratory, cores of Boom Clay are vacuum-packed in Al-coated-poly-ethylene barrier foil to be best preserved at original hydric state. Because clay microstructures are very sensitive to dehydration, the validity of investigations done on such preserved or/and dried samples is often questionable. Desbois et al. (2009, 2013, 2014) showed the possibility to image fluid-filled porosity in Boom Clay, by using the FIB-cryo-SEM (FIB: Focussed Ion Beam) and FIB-cryo-SEM (BIB: Broad Ion Beam) techniques. However, surprisingly in Desbois et al. (2014), BIB-cryo-SEM experiments on Boom Clay, shown that the majority of the pores were fluid-free, contrasting with result in Desbois et al. (2009). In Desbois et al. (2014), several reasons were discussed to explain such discrepancies. The likely ones are the sealing efficiency of the Al-barrier foil at long term and the volume expansion due to the release of in-situ stress after core extraction, contributing both to dehydration and microfabric damage. This contribution presents the newest results based on cryo-BIB-SEM. Small pieces (30 mm3) of Boom Clay were preserved in liquid nitrogen after the core extraction at the MOL/Dessel Underground Research Laboratory in Belgium. A maximum of ten minutes time span was achieved between opening the core, the sub-sample extraction and the quenching of sub-samples in liquid nitrogen. First results show that all pores visible at cryo-SEM resolution are water saturated. However, water

Critical elements in sediment-hosted deposits (clastic-dominated Zn-Pb-Ag, Mississippi Valley-type Zn-Pb, sedimentary rock-hosted Stratiform Cu, and carbonate-hosted Polymetallic Deposits): A review: Chapter 12

USGS Publications Warehouse

Marsh, Erin; Hitzman, Murray W.; Leach, David L.

2016-01-01

Some sediment-hosted base metal deposits, specifically the clastic-dominated (CD) Zn-Pb deposits, carbonate-hosted Mississippi Valley-type (MVT) deposits, sedimentary-rock hosted stratiform copper deposits, and carbonate-hosted polymetallic (“Kipushi type”) deposits, are or have been important sources of critical elements including Co, Ga, Ge, and Re. The generally poor data concerning trace element concentrations in these types of sediment-hosted ores suggest that there may be economically important concentrations of critical elements yet to be recognized.

Properties of Clay for Ceramics with Rock Waste for Production Structural Block by Pressing and Firing

NASA Astrophysics Data System (ADS)

Cerqueira, N. A.; Choe, D.; Alexandre, J.; Azevedo, A. R. G.; Xavier, C. G.; Souza, V. B.

Building work requires optimization of materials and labor, so that the execution of its subsystems contribute to the quality, reduce costs, decrease waste in buildings, productivity, practicality and especially agility. Thus, the fitting blocks can contribute in this direction. This work therefore consists of physical characterization (determination of fitness levels, grain size and bulk density), chemical (EDX) and thermal (DTA and TGA) sample clay Campos dos Goytacazes-RJ and waste rock ornamental Cachoeiro de Itapemirim-ES, to verify potential for producing red ceramic blocks, pressed and burned, male and female type. The output of block will be with different pe rcentages of incorporation of residues of ornamental rocks (0%, 5% and 10%). With the results obtained, it was found that the raw materials under consideration has the potential for application in the production of ceramic articles.

Interpretation of K-Ar dates of illitic clays from sedimentary rocks aided by modeling

USGS Publications Warehouse

Srodon, J.; Clauer, Norbert; Eberl, D.D.D.

2002-01-01

K-Ar dates of illitic clays from sedimentary rocks may contain "mixed ages," i.e., may have ages that are intermediate between the ages of end-member events. Two phenomena that may cause mixed ages are: (1) long-lasting reaction during the burial illitization of smectite: and (2) physical mixing of detrital and diagenetic components. The first phenomenon was investigated by simulation of illitization reactions using a nucleation and growth mechanism. These calculations indicate that values for mixed ages are related to burial history: for an equivalent length of reaction time, fast burial followed by slow burial produces much older mixed ages than slow burial followed by fast. The type of reaction that occured in a rock can be determined from the distribution of ages with respect to the thickness of illite crystals. Dating of artificial mixtures confirms a non-linear relation between mixed ages and the proportions of the components. Vertical variation of K-Ar age dates from Gulf Coast shales can be modeled by assuming diagenetic illitization that overprints a subtle vertical trend (presumably of sedimentary origin) in detrital mineral content.

Deformation of host rocks and flow of magma during growth of minette dikes and breccia-bearing intrusions near Ship Rock, New Mexico

USGS Publications Warehouse

Delaney, Paul T.; Pollard, David D.

1981-01-01

We have studied a small group of minette dikes and plugs that crop out within a flat-lying sequence of siltstone and shale near Ship Rock, a prominent volcanic throat of tuff breccia in northwestern New Mexico. Seven dikes form a radial pattern about Ship Rock we describe in detail the northeastern dike, which has an outcrop length of about 2,900 m, an average thickness of 2.3 m, and a maximum thickness of 7.2 m. The dike is composed of 35 discrete segments arranged in echelon; orientation. of dike segments ranges systematically from N. 52? E. to N. 66? E. A prominent joint set strikes parallel to the segments and is localized within several tens of meters of the dike. Regional joint patterns display no obvious relation to dike orientation. Small offsets of segment contacts, as well as wedge-shaped bodies of crumpled host rock within segments mark the sites of coalescence of smaller segments during dike growth. Bulges in the dike contact, which represent a nondilational component of growth, indicate that wall rocks were brecciated and eroded during the flow of magma. Breccias make up about 9 percent of the 7,176-m 2 area of the dike, are concentrated in its southwest half, and are commonly associated with its thickest parts. We also describe three subcircular plugs; each plug is smaller than 30 m in diameter, is laterally associated with a dike, and contains abundant breccias. Field evidence indicates that these plugs grew from the dikes by brecciation and erosion of wallrocks and that the bulges in the contact of the northeastern dike represent an initial stage of this process. From continuum-mechanical models of host-rock deformation, we conclude that dike propagation was the dominant mechanism for creating conduits for magma ascent where the host rock was brittle and elastic. At a given driving pressure, dikes dilate to accept greater volumes of magma than plugs, and for a given dilation, less work is done on the host rocks. In addition, the pressure required

Porosity and Permeability Evolution in Cemented Rock Cores under Reactive Flowing Conditions: Comparative Analysis between Limestone and Sandstone Host Rocks

NASA Astrophysics Data System (ADS)

Cao, P.; Karpyn, Z.; Li, L.

2013-12-01

CO2-brine has the potential to alter wellbore cement in depleted oil and gas reservoirs under geological CO2 sequestration conditions. A better understanding of CO2-brine-cement-rock interaction is needed to evaluate the seal integrity of candidate sequestration formation in the long run. This work investigates possible alteration of wellbore cement when bonded by different host formation rock upon exposure to CO2-saturated brine. Composite cement-sandstone and cement-limestone core samples were created to perform reactive coreflood experiments. After an eight-day dynamic flow-through period, both cores had a similar extent of porosity increase, while the cement-limestone core experienced a ten-fold higher increase in permeability. With the aid of X-ray Micro-CT imaging and Scanning Electron Microscopy, it is observed that cement underwent greater degradation at the cement-sandstone interface. Degradation of cement-limestone core mainly took place on the host rock matrix. Worm holes were developed and a solution channel was formed in the limestone, creating a dominant flow path that altered both flow and reaction behavior. Limestone buffered the injected acidic brine preventing further deterioration of cement near the core outlet. Changes in fluid chemistry of limestone and sandstone coreflood effluents are compared. Results from this work are aimed at assisting the development and validation of robust reactive transport models through direct measurement of cemented rock core porosity and permeability evolution as well as the effluent aqueous chemistry change. This will subsequently improve predictive capabilities of reactive transport models associated with CO2 sequestration in geologic environments. Permeability Evolution of Cement-Rock Core Sample during Dynamic Flow of CO2-Brine

Study of Usage Areas of Clay Samples of Asphaltite Quarries in Sirnak, Turkey

NASA Astrophysics Data System (ADS)

Bilgin, Oyku

2017-12-01

The asphaltite of Sirnak, Turkey are in the form of 12 veins and their total reserves are anticipated to be approximately 200 million tons in a field of 25.000 hectares. The asphaltites at the Sirnak region are in the form of fault and crack fillings and take place together with clay minerals at their side rock. The main raw materials used in the production of cement are limestone, clay and marn known as sedimentary rocks. Limestone for CaO and clay minerals for SiO2, Al2O3, and Fe2O3, which are the main compounds of clinker production, are the main raw materials. Other materials containing these four oxides like marn are also used as cement raw material. Conformity levels of the raw materials to be used in cement production vary according to their chemical compounds. The rocks to be used as clay mineral are evaluated by taking the rate of silicate and alumina into consideration. The soils suitable for brick-tile productions are named as sandy clay. Their difference from the ceramic clays is that they are richer in terms of iron, silica and carbonate. These soils are also known under the names such as clay, arid, alluvium, silt, loam and argil. Inside these soils, minerals such as quartz, montmorillonite, kaolinite, calcite, limonite, hidromika, sericite, illite, and chlorite are available. Some parts of the soils consist of clays in amorphous structure. Limestone parts, gypsums, organic substances and bulky rock residuals spoil the quality. The soils suitable for brick production may not be suitable for tile production. In this case, their sandy soils should be mixed up with the clays with fine granule structure which is high in plasticity. During asphaltite mining in Sirnak region, clays forming side rock are gathered at dump sites. In this study; SQX analyses of the clay samples taken from Avgamasya, Seridahli and Segürük asphaltite veins run in Sirnak region are carried out and their usage areas are searched.

Finite-element modeling of magma chamber-host rock interactions prior to caldera collapse

NASA Astrophysics Data System (ADS)

Kabele, Petr; Žák, Jiří; Somr, Michael

2017-06-01

Gravity-driven failure of shallow magma chamber roofs and formation of collapse calderas are commonly accompanied by ejection of large volumes of pyroclastic material to the Earth's atmosphere and thus represent severe volcanic hazards. In this respect, numerical analysis has proven as a key tool in understanding the mechanical conditions of caldera collapse. The main objective of this paper is to find a suitable approach to finite-element simulation of roof fracturing and caldera collapse during inflation and subsequent deflation of shallow magma chambers. Such a model should capture the dominant mechanical phenomena, for example, interaction of the host rock with magma and progressive deformation of the chamber roof. To this end, a comparative study, which involves various representations of magma (inviscid fluid, nearly incompressible elastic, or plastic solid) and constitutive models of the host rock (fracture and plasticity), was carried out. In particular, the quasi-brittle fracture model of host rock reproduced well the formation of tension-induced radial and circumferential fractures during magma injection into the chamber (inflation stage), especially at shallow crustal levels. Conversely, the Mohr-Coulomb shear criterion has shown to be more appropriate for greater depths. Subsequent magma withdrawal from the chamber (deflation stage) results in further damage or even collapse of the chamber roof. While most of the previous studies of caldera collapse rely on the elastic stress analysis, the proposed approach advances modeling of the process by incorporating non-linear failure phenomena and nearly incompressible behaviour of magma. This leads to a perhaps more realistic representation of the fracture processes preceding roof collapse and caldera formation.

Near-surface clay authigenesis in exhumed fault rock of the Alpine Fault Zone (New Zealand); O-H-Ar isotopic, XRD and chemical analysis of illite and chlorite

NASA Astrophysics Data System (ADS)

Boles, Austin; Mulch, Andreas; van der Pluijm, Ben

2018-06-01

Exhumed fault rock of the central Alpine Fault Zone (South Island, New Zealand) shows extensive clay mineralization, and it has been the focus of recent research that aims to describe the evolution and frictional behavior of the fault. Using Quantitative X-ray powder diffraction, 40Ar/39Ar geochronology, hydrogen isotope (δD) geochemistry, and electron microbeam analysis, we constrain the thermal and fluid conditions of deformation that produced two predominant clay phases ubiquitous to the exposed fault damage zone, illite and chlorite. Illite polytype analysis indicates that most end-member illite and chlorite material formed in equilibrium with meteoric fluid (δD = -55 to -75‰), but two locations preserve a metamorphic origin of chlorite (δD = -36 to -45‰). Chlorite chemical geothermometry constrains crystal growth to T = 210-296 °C. Isotopic analysis also constrains illite growth to T < 100 °C, consistent with the mineralogy, with Ar ages <0.5 Ma. High geothermal gradients in the study area promoted widespread, near-surface mineralization, and limited the window of clay authigenesis in the Alpine Fault Zone to <5 km for chlorite and <2 km for illite. This implies a significant contrast between fault rock exposed at the surface and that at depth, and informs discussions about fault strength, clays and frictional behavior.

Host rocks and their alterations as related to uranium-bearing veins in the United States

USGS Publications Warehouse

Walker, George W.

1956-01-01

This paper, dealing with the different kinds of host rocks and their alterations associated with uranium-bearing veins in the United States, is a chapter of a comprehensive report entitled , "Geology of uranium-bearing vein deposits in the United States," in preparation by George W. Walker, Frank W. Osterwald, and others. The comprehensive report will include detailed information on tectonic and structural setting, kinds of host rocks, wall-rock alteration, mineralogy, physical characteristics, processes of deposition, and concepts of origin of uraniferous veins; but, because it will not be completed until sometime in the future, some chapters of the report are being transmitted as they are finished. Part of an introductory chapter to the comprehensive report entitled, "Classification and distribution of uranium-bearing veins in the United States" (Walker and Osterwald, 1956) has already been transmitted; several of the terms used herein are defined in the introductory chapter. Data included in this chapter demonstrate that uranium-bearing veins are: 1) in rocks of nearly all textural, chemical, and mineralogic types; 2) most abundant in holocrystalline, commonly equigranular, igeneous and metamorphic rocks characterized by a moderate to high silica content and and by similar physical properties. Although some of the physiochemical properties of the host rocks are discussed in terms of favorability or nonfavoribility for uranium deposition, the principal purpose of this chapter is to establish the petroloic environment in which uranium-bearing veins have been found. Because favorability or nonfavorability of host rocks is related complexly to the chemistry of ore solutions and to methods or uranium transport and deposition, several hypothetical processes of transport and deposition have been referred to briefly; these and other hypotheses will be outlines and discussed in greater detail in a subsequent chapter. The compilation of data leading to this report and its

NMR imaging and cryoporometry of swelling clays

NASA Astrophysics Data System (ADS)

Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

2010-05-01

Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic

Clay mineralogy of weathering profiles from the Carolina Piedmont.

USGS Publications Warehouse

Loferski, P.J.

1981-01-01

Saprolite profiles (12) that formed over various crystalline rocks from the Charlotte 1o X 2o quadrangle showed overall similarity in their clay mineralogy to depths of 6 to 45 m indicating control by weathering processes rather than by rock type. Most saprolite contained 10-25% clay, and ranged 3 to 70%. Kaolinite and halloysite composed = or >75% of the clay fraction of most samples. The ratio kaolinite:halloysite ranged widely, from 95% kaolinite to 90% halloysite, independent of depth. Clay-size mica was present in all profiles, and ranged 5-75% over a sericite schist. Mixed-layer mica-smectite and mica-vermiculite were subordinate; discrete smectite and vermiculite were rare. The abundance of halloysite indicates a continuously humid environment since the time of profile formation, because of the rapidity with which halloysite dehydrates irreversibly. -R.S.M.

Illitization within bentonite engineered barrier system in clay repositories for nuclear waste and its effect on the swelling stress: a coupled THMC modeling study

NASA Astrophysics Data System (ADS)

Zheng, L.; Rutqvist, J.; Birkholzer, J. T.; Liu, H. H.

2014-12-01

Geological repositories for disposal of high-level nuclear waste generally rely on a multi-barrier system to isolate radioactive waste from the biosphere. An engineered barrier system (EBS), which comprises in many design concepts a bentonite backfill, is widely used. Clay formations have been considered as a host rock throughout the world. Illitization, the transformation of smectite to illite, could compromise some beneficiary features of EBS bentonite and clay host rock such as sorption and swelling capacity. It is the major determining factor to establish the maximum design temperature of the repositories because it is believed that illitization could be greatly enhanced at temperatures higher than 100 oC. However, existing experimental and modeling studies on the occurrence of illitization and related performance impacts are not conclusive, in part because the relevant couplings between the thermal, hydrological, chemical, and mechanical (THMC) processes have not been fully represented in the models. Here we present a fully coupled THMC simulation study of a generic nuclear waste repository in a clay formation with a bentonite-backfilled EBS. Two scenarios were simulated for comparison: a case in which the temperature in the bentonite near the waste canister can reach about 200 oC and a case in which the temperature in the bentonite near the waste canister peaks at about 100 oC. The model simulations demonstrate that illitization is in general more significant under higher temperature. However, the quantity of illitization is affected by many chemical factors and therefore varies a great deal. The most important chemical factors are the concentration of K in the pore water as well as the abundance and dissolution rate of K-feldspar. For the particular case and bentonite properties studied, the reduction in swelling stress as a result of chemical changes vary from 2% up to 70% depending on chemical and temperature conditions, and key mechanical parameters. The

Air and groundwater flow at the interface between fractured host rock and a bentonite buffer

NASA Astrophysics Data System (ADS)

Dessirier, B.; Jarsjo, J.; Frampton, A.

2014-12-01

Designs of deep geological repositories for spent nuclear fuel include several levels of confinement. The Swedish and Finnish concept KBS-3 targets for example sparsely fractured crystalline bedrock as host formation and would have the waste canisters embedded in an engineered buffer of compacted MX-80 bentonite. The host rock is a highly heterogeneous dual porosity material containing fractures and a rock matrix. Bentonite is a complex expansive porous material. Its water content and mechanical properties are interdependent. Beyond the specific physics of unsaturated flow and transport in each medium, the interface between them is critical. Detailed knowledge of the transitory two-phase flow regime, induced by the insertion of the unsaturated buffer in a saturated rock environment, is necessary to assess the performance of planned KBS-3 deposition holes. A set of numerical simulations based on the equations of two-phase flow for water and air in porous media were conducted to investigate the dynamics of air and groundwater flow near the rock/bentonite interface in the period following installation of the unsaturated bentonite buffer. We assume state of the two-phase flow parameter values for bentonite from laboratory water uptake tests and typical fracture and rock properties from the Äspö Hard rock laboratory (Sweden) gathered under several field characterization campaigns. The results point to desaturation of the rock domain as far as 10 cm away from the interface into matrix-dominated regions for up to 160 days. Similar observations were made during the Bentonite Rock Interaction Experiment (BRIE) at the Äspö HRL, with a desaturation sustained for even longer times. More than the mere time to mechanical and hydraulic equilibrium, the occurrence of sustained unsaturated conditions opens the possibility for biogeochemical processes that could be critical in the safety assessment of the planned repository.

Study of gamma spectrometry laboratory measurement in various sediment and vulcanic rocks

NASA Astrophysics Data System (ADS)

Nurhandoko, Bagus Endar B.; Kurniadi, Rizal; Rizka Asmara Hadi, Muhammad; Rizal Komara, Insan

2017-01-01

Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources. This method is powerful to characterize some minerals, especially to differentiate rocks which contains among Potassium, Uranium, dan Thorium. Rock contains radioactive material which produce gamma rays in various energies and intensities. When these emissions are detected and analyzed with a spectroscopy system, a gamma-ray energy spectrum can be used as indicator for mineral content of rock. Some sediment and vulcanic rock have been collected from East Java Basin. Samples are ranging from Andesite vulcanics, Tuff, Shale, various vulcanic clay and Alluvial clay. We present some unique characteristics of gamma spectrometry in various sedimentar and vulcanic rocks of East Java Basins. Details contents of gamma ray spectra give enrichments to characterize sample of sediment and vulcanic in East Java. Weathered vulcanic clay has lower counting rate of gamma ray than alluvial deltaic clay counting rate. Therefore, gamma spectrometrometry can be used as tool for characterizing the enviroment of clay whether vulcanic or alluvial-deltaic. This phenomena indicates that gamma ray spectrometry can be as tool for characterizing the clay whether it tends to Smectite or Illite

Damage-plasticity model of the host rock in a nuclear waste repository

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koudelka, Tomáš; Kruis, Jaroslav, E-mail: kruis@fsv.cvut.cz

The paper describes damage-plasticity model for the modelling of the host rock environment of a nuclear waste repository. Radioactive Waste Repository Authority in Czech Republic assumes the repository to be in a granite rock mass which exhibit anisotropic behaviour where the strength in tension is lower than in compression. In order to describe this phenomenon, the damage-plasticity model is formulated with the help of the Drucker-Prager yield criterion which can be set to capture the compression behaviour while the tensile stress states is described with the help of scalar isotropic damage model. The concept of damage-plasticity model was implemented inmore » the SIFEL finite element code and consequently, the code was used for the simulation of the Äspö Pillar Stability Experiment (APSE) which was performed in order to determine yielding strength under various conditions in similar granite rocks as in Czech Republic. The results from the performed analysis are presented and discussed in the paper.« less

Nature of parent rocks, mineralization styles and ore genesis of regolith-hosted REE deposits in South China: An integrated genetic model

NASA Astrophysics Data System (ADS)

Li, Yan Hei Martin; Zhao, Wen Winston; Zhou, Mei-Fu

2017-10-01

Regolith-hosted rare earth element (REE) deposits, also called ion-adsorption or weathered crust elution-deposited REE deposits are distributed over Jiangxi, Guangdong, Fujian, Hunan, Guangxi and Yunnan provinces in South China. In general, these deposits can be categorized into the HREE-dominated type, for example the famous Zudong deposit in southern Jiangxi province and the LREE-dominated type, such as the Heling and Dingnan deposits in southern Jiangxi province. Most of these deposits form from weathering of biotite and muscovite granites, syenites, monzogranites, granodiorites, granite porphyries, and rhyolitic tuffs. The parent rocks are generally peraluminous, siliceous, alkaline and contain a variety of REE-bearing minerals. Mostly, REE patterns of regolith are inherited from the parent rocks, and therefore, characteristics of the parent rocks impose a significant control on the ore formation. Data compilation shows that autometasomatism during the latest stage of granite crystallization is likely essential in forming the HREE-enriched granites, whereas LREE-enriched granites could form through magmatic differentiation. These deposits are normally two- to three-fold, but could be up to ten-fold enrichment in REE compared to the parent granites, where the maximum enrichment usually occurs from the lower B to the upper C horizon. Ce shows different behavior with the other REEs. Strongly positive Ce anomalies commonly occur at the upper part of weathering profiles, likely due to oxidation of Ce3+ to Ce4+ and removal of Ce from soil solutions through precipitation of cerianite. Vertical pH and redox gradients in weathering crusts facilitate dissolution of REE-bearing minerals at shallow level and fixation of REE at depth through either adsorption on clay minerals or precipitation of secondary minerals. At the same time, mass removal of major elements plays an important role in concentrating REE in regolith. Combination of mass removal and eluviation

Clay minerals related to the circulation of geothermal fluids in boreholes at Rittershoffen (Alsace, France)

NASA Astrophysics Data System (ADS)

Vidal, Jeanne; Patrier, Patricia; Genter, Albert; Beaufort, Daniel; Dezayes, Chrystel; Glaas, Carole; Lerouge, Catherine; Sanjuan, Bernard

2018-01-01

Two geothermal wells, GRT-1 and GRT-2, were drilled into the granite at Rittershoffen (Alsace, France) in the Upper Rhine Graben to exploit geothermal resources at the sediment-basement interface. Brine circulation occurs in a permeable fracture network and leads to hydrothermal alteration of the host rocks. The goal of the study was to characterize the petrography and mineralogy of the altered rocks with respect to the permeable fracture zones in the granitic basement. As clay minerals are highly reactive to hydrothermal alteration, they can be used as indicators of present-day and paleo-circulation systems. Special attention has been paid to the textural, structural and chemical properties of these minerals. The fine-grained clay fraction (< 5 μm) was analyzed around the originally permeable fracture zones to observe the crystal structure of clay minerals using X-ray diffraction. Chemical microanalysis of the clay minerals was performed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The occurrences of mixed layers illite-smectite ( 10% smectite) provide a promising guide for identifying the fracture zones that control the present-day circulation of geothermal fluids in the Rittershoffen wells. However, multistage paleo-circulation systems could lead to an abundance of heterogeneous and fine-grained illitic minerals that could plug the fracture system. The permeability of fracture zones in the GRT-1 well was likely reduced because of an intense illitization, and the well was stimulated. The occurrence of chlorite in the permeable fracture zones of GRT-2 is indicative of less intense illitization, and the natural permeability is much higher in GRT-2 than in GRT-1.

Tourmaline occurrences within the Penamacor-Monsanto granitic pluton and host-rocks (Central Portugal): genetic implications of crystal-chemical and isotopic features

NASA Astrophysics Data System (ADS)

da Costa, I. Ribeiro; Mourão, C.; Récio, C.; Guimarães, F.; Antunes, I. M.; Ramos, J. Farinha; Barriga, F. J. A. S.; Palmer, M. R.; Milton, J. A.

2014-04-01

Tourmalinization associated with peraluminous granitic intrusions in metapelitic host-rocks has been widely recorded in the Iberian Peninsula, given the importance of tourmaline as a tracer of granite magma evolution and potential indicator of Sn-W mineralizations. In the Penamacor-Monsanto granite pluton (Central Eastern Portugal, Central Iberian Zone), tourmaline occurs: (1) as accessory phase in two-mica granitic rocks, muscovite-granites and aplites, (2) in quartz (±mica)-tourmaline rocks (tourmalinites) in several exocontact locations, and (3) as a rare detrital phase in contact zone hornfels and metapelitic host-rocks. Electron microprobe and stable isotope (δ18O, δD, δ11B) data provide clear distinctions between tourmaline populations from these different settings: (a) schorl-oxyschorl tourmalines from granitic rocks have variable foititic component (X□ = 17-57 %) and Mg/(Mg + Fe) ratios (0.19-0.50 in two-mica granitic rocks, and 0.05-0.19 in the more differentiated muscovite-granite and aplites); granitic tourmalines have constant δ18O values (12.1 ± 0.1 ‰), with wider-ranging δD (-78.2 ± 4.7 ‰) and δ11B (-10.7 to -9.0 ‰) values; (b) vein/breccia oxyschorl [Mg/(Mg + Fe) = 0.31-0.44] results from late, B- and Fe-enriched magma-derived fluids and is characterized by δ18O = 12.4 ‰, δD = -29.5 ‰, and δ11B = -9.3 ‰, while replacement tourmalines have more dravitic compositions [Mg/(Mg + Fe) = 0.26-0.64], close to that of detrital tourmaline in the surrounding metapelitic rocks, and yield relatively constant δ18O values (13.1-13.3 ‰), though wider-ranging δD (-58.5 to -36.5 ‰) and δ11B (-10.2 to -8.8 ‰) values; and (c) detrital tourmaline in contact rocks and regional host metasediments is mainly dravite [Mg/(Mg + Fe) = 0.35-0.78] and oxydravite [Mg/(Mg + Fe) = 0.51-0.58], respectively. Boron contents of the granitic rocks are low (<650 ppm) compared to the minimum B contents normally required for tourmaline saturation in

Incorporation of tramadol drug into Li-fluorohectorite clay: A preliminary study of a medical nanofluid

NASA Astrophysics Data System (ADS)

Valdés, L.; Hernández, D.; de Ménorval, L. Ch.; Pérez, I.; Altshuler, E.; Fossum, J. O.; Rivera, A.

2016-07-01

During the last years, clays have been increasingly explored as hosts for drugs. In the present paper, we have been able to host the non-steroidal anti-inflammatory drug, Tramadol, into the clay Li-fluorohectorite (Li-Fh). We preliminary evaluate its incorporation by means of UV spectroscopy and X ray diffraction. Our results indicate that the clay hosts the drug molecule in its interlayer space. We suggest a set of parameters to guarantee an efficient incorporation process. Future studies will concentrate on the release of the drug from the clay nanofluid.

Fault rock mineralogy and fluid flow in the Coso Geothermal Field, CA

NASA Astrophysics Data System (ADS)

Davatzes, N. C.; Hickman, S. H.

2005-12-01

to differ because the processes that accommodate deformation depend strongly on mineralogy. Frictional strength of quartz-dominated fault rocks in the near surface and in the reservoir should be greater (~0.6) than that in the clay-dominated cap rock (~0.2-0.4). Similarly, permeability should be much lower in foliated clay-rich fault rocks than in quartz-rich fault rocks as evidenced by larger, more connected pores imaged in quartz-rich gouge. Mineral stability is a function of loading, strain rate, temperature, and fluid flow conditions. Which minerals form, and the rates at which they grow is also a key element in determining variations in the magnitude and anisotropy of fault zone properties at Coso. Consequently, we suggest that the development of fault-zone properties depends on the feedback between deformation, resulting changes in permeability, and large-scale fluid flow and the leading to dissolution/precipitation of minerals in the fault rock and adjacent host rock. The implication for Coso is that chemical alteration of otherwise low-porosity crystalline rocks appears to determine the distribution and temporal evolution of permeability in the actively deforming fracture network at small to moderate scales as well as along major, reservoir-penetrating fault zones.

Geology and Refractory Clay Deposits of the Haldeman and Wrigley Quadrangles, Kentucky

USGS Publications Warehouse

Patterson, Sam H.; Hosterman, John W.; Huddle, John Warfield

1962-01-01

The Haldeman and Wrigley 7th-minute quadrangles are near the western edge of the eastern Kentucky coal field and cover an area of approximately 117 square miles in parts of Carter, Rowan, Elliott, and Morgan Counties, Ky. The rocks exposed in the two quadrangles are of Early and Late Mississippian and Early and Middle Pennsylvanian age. The Mississippian rocks are composed of the thick Brodhead formation, which consists of siltstone and shale, and eleven thin marine limestone and shale formations, having an aggregate thickness of about 150 feet. The Lee and Breathitt formations, of Pennsylvanian age, consist of sandstone, siltstone, and shale; they also contain thin beds of coal and several beds of underclay, including the economically important Olive Hill clay bed of Crider, 1913. Pennsylvanian rocks include beds of both continental and marine origin. The eleven thin Mississippian formations and the upper-most part of the thick Brodhead formation are truncated by a prominent unconformity on which rocks of Pennsylvanian age rest. The rocks occupy a region of gentle dips between the Cincinnati arch and the Appalachian Mountains. Refractory clay deposits are in the Olive Hill clay bed, which occurs in the lower part of the Lee formation. The Olive Hill clay bed is discontinuous and consists of a series of irregularly shaped lenses. The bed is approximately two-thirds semifiint clay and one-third flint clay, and it contains minor amounts of plastic clay. Some of the flint clay is nearly pure kaolinite, but the semi flint and plastic clay consists of mixtures of kaolinite, illite, and mixed-layer clay minerals. The structure of the kaolinite ranges from highly crystalline to very poorly crystalline 'fireclay' type. The degree of crystallinity of the kaolinite and the hardness of the clay vary inversely with the amount of illite and mixed-layer clay minerals present. The nearly pure kaolinite is believed to have formed by the removal of alkalies and some silica fram

Effects of Host-rock Fracturing on Elastic-deformation Source Models of Volcano Deflation.

PubMed

Holohan, Eoghan P; Sudhaus, Henriette; Walter, Thomas R; Schöpfer, Martin P J; Walsh, John J

2017-09-08

Volcanoes commonly inflate or deflate during episodes of unrest or eruption. Continuum mechanics models that assume linear elastic deformation of the Earth's crust are routinely used to invert the observed ground motions. The source(s) of deformation in such models are generally interpreted in terms of magma bodies or pathways, and thus form a basis for hazard assessment and mitigation. Using discontinuum mechanics models, we show how host-rock fracturing (i.e. non-elastic deformation) during drainage of a magma body can progressively change the shape and depth of an elastic-deformation source. We argue that this effect explains the marked spatio-temporal changes in source model attributes inferred for the March-April 2007 eruption of Piton de la Fournaise volcano, La Reunion. We find that pronounced deflation-related host-rock fracturing can: (1) yield inclined source model geometries for a horizontal magma body; (2) cause significant upward migration of an elastic-deformation source, leading to underestimation of the true magma body depth and potentially to a misinterpretation of ascending magma; and (3) at least partly explain underestimation by elastic-deformation sources of changes in sub-surface magma volume.

Biostratigraphy and structure of paleozoic host rocks and their relationship to Carlin-type gold deposits in the Jerritt Canyon mining district, Nevada

USGS Publications Warehouse

Peters, S.G.; Armstrong, A.K.; Harris, A.G.; Oscarson, R.L.; Noble, P.J.

2003-01-01

The Jerritt Canyon mining district in the northern Independence Range, northern Nevada, contains multiple, nearly horizontal, thrust masses of platform carbonate rocks that are exposed in a series of north- to northeast-elongated, tectonic windows through rocks of the Roberts Mountains allochthon. The Roberts Mountains allochthon was emplaced during the Late Devonian to Early Mississippian Antler orogeny. These thrust masses contain structurally and stratigraphically controlled Carlin-type gold deposits. The gold deposits are hosted in tectonically truncated units of the Silurian to Devonian Hanson Creek and Roberts Mountains Formations that lie within structural slices of an Eastern assemblage of Cambrian to Devonian carbonate rocks. In addition, these multiply thrust-faulted and folded host rocks are structurally interleaved with Mississippian siliciclastic rocks and are overlain structurally by Cambrian to Devonian siliciclastic units of the Roberts Mountains allochthon. All sedimentary rocks were involved in thrusting, high-angle faulting, and folding, and some of these events indicate substantial late Paleozoic and/or Mesozoic regional shortening. Early Pennsylvanian and late Eocene dikes also intrude the sedimentary rocks. These rocks all were uplifted into a northeast-trending range by subsequent late Cenozoic Basin and Range faulting. Eocene sedimentary and volcanic rocks flank part of the range. Pathways of hydrothermal fluid flow and locations of Carlin-type gold orebodies in the Jerritt Canyon mining district were controlled by structural and host-rock geometries within specific lithologies of the stacked thrust masses of Eastern assemblage rocks. The gold deposits are most common proximal to intersections of northeast-striking faults, northwest-striking dikes, and thrust planes that lie adjacent to permeable stratigraphic horizons. The host stratigraphic units include carbonate sequences that contained primary intercrystalline permeability, which

Block Slides on Extremely Weak Tectonic Clay Seams in Openly Folded Tertiary Mud-Rocks at Auckland and the Rangitikei Valley, North Island, New Zealand

NASA Astrophysics Data System (ADS)

Prebble, Warwick M.; Williams, Ann L.

2016-06-01

Block slides have developed on extremely weak, thin clay seams of tectonic origin, parallel to bedding in gently dipping sandstones and mudstones of Tertiary age. Two areas of noted instability are investigated at Auckland and the Rangitikei valley. Dimensions range from 100 m across × 100 m long for short displacement block slides up to 4 km across × 3 km long for large landslide complexes in which block slides are a major component. Displacements of blocks range from incipient (cm) through short (30 m) to 2 or 3 km for large slides. Many of the Auckland slides are dormant but likely to move in a 2000 year return period earthquake or 100 year high intensity rain storm. At Rangitikei there are many active, younger slides. Sliding rates for active failures vary from a few cm/year to 50 m in 30 min. Host rocks are weak to very weak clayey sandstones and sandy mudstones. The seams are rich in smectite. They have polished and crushed walls, may have slickensides and some contain rounded rock fragments. Laboratory shear strength of the seams is 13 kPa cohesion and 13° friction, with a lower bound of 8° at zero cohesion. Strength is increased at the field scale by waviness, steps and splays. Continuity can be demonstrated over distances of hundreds of metres. Key investigation methods were mapping, shafts and trenches. Tectonic uplift, folding and faulting of the weak Tertiary strata and river down-cutting are perpetuating block slide development.

Microstructural controls on the macroscopic behavior of geo-architected rock samples

NASA Astrophysics Data System (ADS)

Mitchell, C. A.; Pyrak-Nolte, L. J.

2017-12-01

Reservoir caprocks, are known to span a range of mechanical behavior from elastic granitic units to visco-elastic shale units. Whether a rock will behave elastically, visco-elastically or plastically depends on both the compositional and textural or microsctructural components of the rock, and how these components are spatially distributed. In this study, geo-architected caprock fabrication was performed to develop synthetic rock to study the role of rock rheology on fracture deformations, fluid flow and geochemical alterations. Samples were geo-architected with Portland Type II cement, Ottawa sand, and different clays (kaolinite, illite, and Montmorillonite). The relative percentages of these mineral components are manipulated to generate different rock types. With set protocols, the mineralogical content, texture, and certain structural aspects of the rock were controlled. These protocols ensure that identical samples with the same morphological and mechanical characteristics are constructed, thus overcoming issues that may arise in the presence of heterogeneity and high anisotropy from natural rock samples. Several types of homogeneous geo-architected rock samples were created, and in some cases the methods were varied to manipulate the physical parameters of the rocks. Characterization of rocks that the samples exhibit good repeatability. Rocks with the same mineralogical content generally yielded similar compressional and shear wave velocities, UCS and densities. Geo-architected rocks with 10% clay in the matrix had lower moisture content and effective porosities than rocks with no clay. The process by which clay is added to the matrix can strongly affect the resulting compressive strength and physical properties of the geo-architected sample. Acknowledgment: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022).

Thermal Analysis of a Nuclear Waste Repository in Argillite Host Rock

NASA Astrophysics Data System (ADS)

Hadgu, T.; Gomez, S. P.; Matteo, E. N.

2017-12-01

Disposal of high-level nuclear waste in a geological repository requires analysis of heat distribution as a result of decay heat. Such an analysis supports design of repository layout to define repository footprint as well as provide information of importance to overall design. The analysis is also used in the study of potential migration of radionuclides to the accessible environment. In this study, thermal analysis for high-level waste and spent nuclear fuel in a generic repository in argillite host rock is presented. The thermal analysis utilized both semi-analytical and numerical modeling in the near field of a repository. The semi-analytical method looks at heat transport by conduction in the repository and surroundings. The results of the simulation method are temperature histories at selected radial distances from the waste package. A 3-D thermal-hydrologic numerical model was also conducted to study fluid and heat distribution in the near field. The thermal analysis assumed a generic geological repository at 500 m depth. For the semi-analytical method, a backfilled closed repository was assumed with basic design and material properties. For the thermal-hydrologic numerical method, a repository layout with disposal in horizontal boreholes was assumed. The 3-D modeling domain covers a limited portion of the repository footprint to enable a detailed thermal analysis. A highly refined unstructured mesh was used with increased discretization near heat sources and at intersections of different materials. All simulations considered different parameter values for properties of components of the engineered barrier system (i.e. buffer, disturbed rock zone and the host rock), and different surface storage times. Results of the different modeling cases are presented and include temperature and fluid flow profiles in the near field at different simulation times. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and

Composition, Alteration, and Texture of Fault-Related Rocks from Safod Core and Surface Outcrop Analogs: Evidence for Deformation Processes and Fluid-Rock Interactions

NASA Astrophysics Data System (ADS)

Bradbury, Kelly K.; Davis, Colter R.; Shervais, John W.; Janecke, Susanne U.; Evans, James P.

2015-05-01

We examine the fine-scale variations in mineralogical composition, geochemical alteration, and texture of the fault-related rocks from the Phase 3 whole-rock core sampled between 3,187.4 and 3,301.4 m measured depth within the San Andreas Fault Observatory at Depth (SAFOD) borehole near Parkfield, California. This work provides insight into the physical and chemical properties, structural architecture, and fluid-rock interactions associated with the actively deforming traces of the San Andreas Fault zone at depth. Exhumed outcrops within the SAF system comprised of serpentinite-bearing protolith are examined for comparison at San Simeon, Goat Rock State Park, and Nelson Creek, California. In the Phase 3 SAFOD drillcore samples, the fault-related rocks consist of multiple juxtaposed lenses of sheared, foliated siltstone and shale with block-in-matrix fabric, black cataclasite to ultracataclasite, and sheared serpentinite-bearing, finely foliated fault gouge. Meters-wide zones of sheared rock and fault gouge correlate to the sites of active borehole casing deformation and are characterized by scaly clay fabric with multiple discrete slip surfaces or anastomosing shear zones that surround conglobulated or rounded clasts of compacted clay and/or serpentinite. The fine gouge matrix is composed of Mg-rich clays and serpentine minerals (saponite ± palygorskite, and lizardite ± chrysotile). Whole-rock geochemistry data show increases in Fe-, Mg-, Ni-, and Cr-oxides and hydroxides, Fe-sulfides, and C-rich material, with a total organic content of >1 % locally in the fault-related rocks. The faults sampled in the field are composed of meters-thick zones of cohesive to non-cohesive, serpentinite-bearing foliated clay gouge and black fine-grained fault rock derived from sheared Franciscan Formation or serpentinized Coast Range Ophiolite. X-ray diffraction of outcrop samples shows that the foliated clay gouge is composed primarily of saponite and serpentinite, with localized

Hydration Phase Diagram of Clay Particles from Molecular Simulations.

PubMed

Honorio, Tulio; Brochard, Laurent; Vandamme, Matthieu

2017-11-07

Adsorption plays a fundamental role in the behavior of clays. Because of the confinement between solid clay layers on the nanoscale, adsorbed water is structured in layers, which can occupy a specific volume. The transition between these states is intimately related to key features of clay thermo-hydro-mechanical behavior. In this article, we consider the hydration states of clays as phases and the transition between these states as phase changes. The thermodynamic formulation supporting this idea is presented. Then, the results from grand canonical Monte Carlo simulations of sodium montmorillonite are used to derive hydration phase diagrams. The stability analysis presented here explains the coexistence of different hydration states at clay particle scale and improves our understanding of the irreversibilities of clay thermo-hydro-mechanical behavior. Our results provide insights into the mechanics of the elementary constituents of clays, which is crucial for a better understanding of the macroscopic behavior of clay-rich rocks and soils.

Subsurface water and clay mineral formation during the early history of Mars.

PubMed

Ehlmann, Bethany L; Mustard, John F; Murchie, Scott L; Bibring, Jean-Pierre; Meunier, Alain; Fraeman, Abigail A; Langevin, Yves

2011-11-02

Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presence would indicate past surface conditions warmer and wetter than at present. However, available data instead indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachian rock record dominated by evidence of subsurface waters. Cold, arid conditions with only transient surface water may have characterized Mars's surface for over 4 billion years, since the early-Noachian period, and the longest-duration aqueous, potentially habitable environments may have been in the subsurface.

The influence of shale depositional fabric on the kinetics of hydrocarbon generation through control of mineral surface contact area on clay catalysis

NASA Astrophysics Data System (ADS)

Rahman, Habibur M.; Kennedy, Martin; Löhr, Stefan; Dewhurst, David N.; Sherwood, Neil; Yang, Shengyu; Horsfield, Brian

2018-01-01

Accurately assessing the temperature and hence the depth and timing of hydrocarbon generation is a critical step in the characterization of a petroleum system. Clay catalysis is a potentially significant modifier of hydrocarbon generation temperature, but experimental studies of clay catalysis show inconsistent or contradictory results. This study tests the hypothesis that source rock fabric itself is an influence on clay mineral catalysis as it controls the extent to which organic matter and clay minerals are physically associated. Two endmember clay-organic fabrics distinguish the source rocks studied: (1) a particulate fabric where organic matter is present as discrete, >5 μm particles and (2) a nanocomposite fabric in which amorphous organic matter is associated with clay mineral surfaces at sub-micron scale. High-resolution electron imaging and bulk geochemical characterisation confirm that samples of the Miocene Monterey Formation (California) are representative of the nanocomposite source rock endmember, whereas samples from the Permian Stuart Range Formation (South Australia) represent the particulate source rock endmember. Kinetic experiments are performed on paired whole rock and kerogen isolate samples from these two formations using open system, non-isothermal pyrolysis at three different heating rates (0.7, 2 and 5 K/min) to determine the effects of the different shale fabrics on hydrocarbon generation kinetics. Extrapolation to a modelled geological heating rate shows a 20 °C reduction in the onset temperature of hydrocarbon generation in Monterey Formation whole rock samples relative to paired kerogen isolates. This result is consistent with the Monterey Formations's nanocomposite fabric where clay catalysis can proceed because reactive clay minerals are intimately associated with organic matter. By contrast, there is no significant difference in the modelled hydrocarbon generation temperature of paired whole rock and kerogen isolates from the

Host-Parasite Interactions and Population Dynamics of Rock Ptarmigan.

PubMed

Stenkewitz, Ute; Nielsen, Ólafur K; Skírnisson, Karl; Stefánsson, Gunnar

2016-01-01

Populations of rock ptarmigan (Lagopus muta) in Iceland fluctuate in multiannual cycles with peak numbers c. every 10 years. We studied the ptarmigan-parasite community and how parasites relate to ptarmigan age, body condition, and population density. We collected 632 ptarmigan in northeast Iceland in early October from 2006 to 2012; 630 (99.7%) were infected with at least one parasite species, 616 (98%) with ectoparasites, and 536 (85%) with endoparasites. We analysed indices for the combined parasite community (16 species) and known pathogenic parasites, two coccidian protozoans Eimeria muta and Eimeria rjupa, two nematodes Capillaria caudinflata and Trichostrongylus tenuis, one chewing louse Amyrsidea lagopi, and one skin mite Metamicrolichus islandicus. Juveniles overall had more ectoparasites than adults, but endoparasite levels were similar in both groups. Ptarmigan population density was associated with endoparasites, and in particular prevalence of the coccidian parasite Eimeria muta. Annual aggregation level of this eimerid fluctuated inversely with prevalence, with lows at prevalence peak and vice versa. Both prevalence and aggregation of E. muta tracked ptarmigan population density with a 1.5 year time lag. The time lag could be explained by the host specificity of this eimerid, host density dependent shedding of oocysts, and their persistence in the environment from one year to the next. Ptarmigan body condition was negatively associated with E. muta prevalence, an indication of their pathogenicity, and this eimerid was also positively associated with ptarmigan mortality and marginally inversely with fecundity. There were also significant associations between fecundity and chewing louse Amyrsidea lagopi prevalence (negative), excess juvenile mortality and nematode Capillaria caudinflata prevalence (positive), and adult mortality and skin mite Metamicrolichus islandicus prevalence (negative). Though this study is correlational, it provides strong

Track of fluid paleocirculation in dolomite host rock at regional scale by the Anisotropy of Magnetic Susceptibility (AMS): An example from Aptian carbonates of La Florida, Northern Spain

NASA Astrophysics Data System (ADS)

Essalhi, Mourad; Sizaret, Stanislas; Barbanson, Luc; Chen, Yan; Branquet, Yannick; Panis, Dominique; Camps, Pierre; Rochette, Pierre; Canals, Angels

2009-01-01

The present study aims to apply the AMS method (Anisotropy of Magnetic Susceptibility) at a regional scale to track the fluid circulation direction that has produced an iron metasomatism within pre-existing dolomite host rock. The Urgonian formations hosting the Zn-Pb mineralizations in La Florida (Cantabria, northern Spain) have been taken as target for this purpose. Sampling was carried out, in addition to ferroan dolomite host rock enclosing the Zn-Pb mineralizations, in dolomite host rock and limestone to make the comparison possible between magnetic signals from mineralized rocks, where fluid circulation occurred, and their surrounding formations. AMS study was coupled with petrofabric analysis carried out by texture goniometry, Scanning Electron Microscopy (SEM) observations and also Shape Preferred Orientation (SPO) statistics. SEM observations of ferroan dolomite host rock illustrate both bright and dark grey ribbons corresponding respectively to Fe enriched and pure dolomites. SPO statistics applied on four images from ferroan dolomite host rock give a well-defined orientation of ribbons related to the intermediate axis of magnetic susceptibility K2. For AMS data, two magnetic fabrics are observed. The first one is observed in ferroan dolomite host rock and characterized by a prolate ellipsoid of magnetic susceptibility with a vertical magnetic lineation. The magnetic susceptibility carrier is Fe-rich dolomite. These features are probably acquired during metasomatic fluid circulations. In Fe-rich dolomite host rock, ‹ c› axes are vertical. As a rule, (0001) planes (i.e. planes perpendicular to ‹ c› axes) are isotropic with respect to crystallographic properties. So, the magnetic anisotropy measured in this plane should reflect crystallographic modification due to fluid circulation. This is confirmed by the texture observed using the SEM. Consequently, AMS results show a dominant NE-SW elongation interpreted as the global circulation direction and a

Microstructures and deformation mechanisms in Opalinus Clay: insights from scaly clay from the Main Fault in the Mont Terri Rock Laboratory (CH)

NASA Astrophysics Data System (ADS)

Laurich, Ben; Urai, Janos L.; Nussbaum, Christophe

2017-01-01

The Main Fault in the shaly facies of Opalinus Clay is a small reverse fault formed in slightly overconsolidated claystone at around 1 km depth. The fault zone is up to 6 m wide, with micron-thick shear zones, calcite and celestite veins, scaly clay and clay gouge. Scaly clay occurs in up to 1.5 m wide lenses, providing hand specimens for this study. We mapped the scaly clay fabric at 1 m-10 nm scale, examining scaly clay for the first time using broad-ion beam polishing combined with scanning electron microscopy (BIB-SEM). Results show a network of thin shear zones and microveins, separating angular to lensoid microlithons between 10 cm and 10 µm in diameter, with slickensided surfaces. Our results show that microlithons are only weakly deformed and that strain is accumulated by fragmentation of microlithons by newly formed shear zones, by shearing in the micron-thick zones and by rearrangement of the microlithons.The scaly clay aggregates can be easily disintegrated into individual microlithons because of the very low tensile strength of the thin shear zones. Analyses of the microlithon size by sieving indicate a power-law distribution model with exponents just above 2. From this, we estimate that only 1 vol % of the scaly clay aggregate is in the shear zones.After a literature review of the hypotheses for scaly clay generation, we present a new model to explain the progressive formation of a self-similar network of anastomosing thin shear zones in a fault relay. The relay provides the necessary boundary conditions for macroscopically continuous deformation. Localization of strain in thin shear zones which are locally dilatant, and precipitation of calcite veins in dilatant shear fractures, evolve into complex microscale re-partitioning of shear, forming new shear zones while the microlithons remain much less deformed internally and the volume proportion of the µm-thick shear zones slowly increases. Grain-scale deformation mechanisms are microfracturing

Chemistry of Martian Rock Esperance

NASA Image and Video Library

2013-06-07

This triangle plot shows the relative concentrations of some of the major chemical elements in the Martian rock Esperance. The compositions of average Martian crust and of montmorillonite, a common clay mineral, are shown.

Sulfates and Clays in Columbus Crater, Mars

NASA Image and Video Library

2011-11-21

Sulfates are found overlying clay minerals in sediments within Columbus Crater, a depression that likely hosted a lake in the past in this image based on information from NASA Mars Reconnaissance Orbiter.

Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

USGS Publications Warehouse

Solum, J.G.; van der Pluijm, B.A.; Peacor, D.R.

2005-01-01

Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ???40% in 1Md illite relative to protolith, whereas altered protolith in the damage zone is enriched ???40% in illite-smectite relative to gouge and up to ???50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1Md) gouge illite (63??2 Ma) and illite-smectite in the damage zone (60??2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone. ?? 2005 Elsevier Ltd. All rights reserved.

Safety-relevant hydrogeological properties of the claystone barrier of a Swiss radioactive waste repository: An evaluation using multiple lines of evidence

NASA Astrophysics Data System (ADS)

Gautschi, Andreas

2017-09-01

In Switzerland, the Opalinus Clay - a Jurassic (Aalenian) claystone formation - has been proposed as the first-priority host rock for a deep geological repository for both low- and intermediate-level and high-level radioactive wastes. An extensive site and host rock investigation programme has been carried out during the past 30 years in Northern Switzerland, comprising extensive 2D and 3D seismic surveys, a series of deep boreholes within and around potential geological siting regions, experiments in the international Mont Terri Rock Laboratory, compilations of data from Opalinus Clay in railway and motorway tunnels and comparisons with similar rocks. The hydrogeological properties of the Opalinus Clay that are relevant from the viewpoint of long-term safety are described and illustrated. The main conclusions are supported by multiple lines of evidence, demonstrating consistency of conclusions based on hydraulic properties, porewater chemistry, distribution of natural tracers across the Opalinus Clay as well as small- and large-scale diffusion models and the derived conceptual understanding of solute transport.

Muon tomography in the Mont Terri underground rock laboratory

NASA Astrophysics Data System (ADS)

Lesparre, N.; Gibert, D.; Marteau, J.; Carlus, B.; Nussbaum, C.

2012-04-01

The Mont Terri underground rock laboratory (Switzerland) was excavated in a Mesozoic shale formation constituted by Opalinus clay. This impermeable formation presents suitable properties for hosting repository sites of radioactive waste. A muon telescope has been placed in this laboratory in October 2009 to establish the feasibility of the muon tomography and to test the sensor performance in a calm environment, where we are protected from atmospheric noisy particles. However, the presence of radon in the gallery as well as charged particles issued from the decay of gamma rays may create a background noise. This noise shift and smooths the signal inducing an under estimation of the rock density. The uncorrelated background has been measured by placing the planes of detection in anti-coincidence. This estimation is preponderant and has to be combined to the theoretical feasibility evaluation to determine the best experimental set-up to observe muon flux fluctuations due to density variations. The muon densitometry experience is here exposed with the estimation of its feasibility. The data acquired from different locations inside the underground laboratory are presented. They are compared to two models representing the layer above the laboratory corresponding to a minimum and a maximum muon flux expectation depending on the values of the rock density.

Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility

NASA Astrophysics Data System (ADS)

Ambers, R. K.; Stine, M. B.

2005-12-01

Soil scientists concerned with erosion of agricultural fields and geotechnical engineers concerned with the mechanical behavior of soils under different conditions have both examined the role of clay mineralogy in controlling soil/sediment properties. Fluvial geomorphologists studying stream channel erosion and stability have focused more on the effects of particle-size distribution, vegetation and rooting. The clay mineralogy of bed and bank sediment has the potential to influence cohesiveness and erodibility, however. The goal of this study is to determine the influence of clay mineralogy on the erodibility of natural stream bank sediment, utilizing techniques drawn from pedology and soil mechanics. Bank samples were collected from eleven sites in small watersheds in central and western Virginia. To obtain sediment containing a range of different clay minerals, watersheds with different types of bedrock were chosen for sampling. Rock types included mafic to felsic metamorphic and igneous rocks, shale, sandstone, and limestone. Where stream bank materials were clearly stratified, different layers were sampled separately. X-ray diffraction of the clay-fraction of the sediment indicates the presence of kaolinite, illite, vermiculite, and mixed-layer clay minerals in various abundances in the different samples. Clay content is 9-46%, as determined by the hydrometer method, and textures range from silty clay and silt loam to clay loam and sandy loam. Organic mater contents range from 1-5% by the loss-on-ignition method. Bulk density of intact sediment samples averages 1.5 g/cc. Liquid limits range from 23-41 with one sample having a value of 65; plasticity indices range from 15-22. While these tests predict that the samples would show a range of mechanical behaviors, the channel morphology at the sampling sites was not strikingly different, all having steep cut banks eroded primarily by scour with no evidence of mass movement and most having a width/depth ratio around

Rock Levitation by Water and Ice; an Explanation for Trails in Racetrack Playa, California

NASA Astrophysics Data System (ADS)

Kletetschka, G.; Ryan, A.; McKinney, E.; Fercana, G.; Schwebler, K. P.; McIntire, L.; Miller, D.; Fox, V. K.; Marbourg, J. M.; Naquin, C. A.; Krzykowski, M.; Wilde, J. R.; Kopp, E. S.; Romine, G.; Yawn, K.; Schoch, I.; McAdam, M.; Burger, D.; Rilee, K.; Jackson, B. K.; Parsons, A. M.; Cheung, C. Y.; Lunar; Planetary Science Academy

2010-12-01

Through a process that is nearly a century-old mystery, rock fragments race over a desiccated layer of sediment in the California desert, forming the infamous rock trails of the Racetrack playa, found in Death Valley, California. Rocks, randomly distributed over the playa, have indented grooves or trails next to them, appearing as if someone had dragged them over the playa surface when wet. Interestingly, no one has ever witnessed the movement of these rocks. Furthermore, the mechanism responsible for these trails behind the rocks has not yet been explained. Rocks have masses ranging from 0.5 kg to 300 kg, and the trails have a chaotic character, with some trails as long as 1/2 km. Each rock has a mound of raised clay on one side and a mud trail on the other; no other unusual marks are visible. A number of trails have no rocks at the end, with only a mound of solid clay where a rock once appeared to be, as if something was pushing the clay forwards to make the trail but disappeared after the trail was made. Measurements of the humidity and temperature of the sediment pointed towards a unique mechanism of how the trails could form on their own and how simple environmental changes could result in the aforementioned trails in the sediment.

Field trip guidebook on environmental impact of clays along the upper Texas coast

NASA Technical Reports Server (NTRS)

Garcia, Theron D.; Ming, Douglas W.; Tuck, Lisa Kay

1991-01-01

The field trip was prepared to provide an opportunity to see first hand some the environmental hazards associated with clays in the Houston, Texas area. Because of the very high clay content in area soils and underlying Beaumont Formation clay, Houston is a fitting location to host the Clay Mineral Society. Examinations were made of (1) expansive soils, (2) subsidence and surface faulting, and (3) a landfill located southeast of Houston at the Gulf Coast Waste Disposal Authority where clay is part of the liner material.

Clay mineral diversity and abundance in sedimentary rocks of Gale crater, Mars.

PubMed

Bristow, Thomas F; Rampe, Elizabeth B; Achilles, Cherie N; Blake, David F; Chipera, Steve J; Craig, Patricia; Crisp, Joy A; Des Marais, David J; Downs, Robert T; Gellert, Ralf; Grotzinger, John P; Gupta, Sanjeev; Hazen, Robert M; Horgan, Briony; Hogancamp, Joanna V; Mangold, Nicolas; Mahaffy, Paul R; McAdam, Amy C; Ming, Doug W; Morookian, John Michael; Morris, Richard V; Morrison, Shaunna M; Treiman, Allan H; Vaniman, David T; Vasavada, Ashwin R; Yen, Albert S

2018-06-01

Clay minerals provide indicators of the evolution of aqueous conditions and possible habitats for life on ancient Mars. Analyses by the Mars Science Laboratory rover Curiosity show that ~3.5-billion year (Ga) fluvio-lacustrine mudstones in Gale crater contain up to ~28 weight % (wt %) clay minerals. We demonstrate that the species of clay minerals deduced from x-ray diffraction and evolved gas analysis show a strong paleoenvironmental dependency. While perennial lake mudstones are characterized by Fe-saponite, we find that stratigraphic intervals associated with episodic lake drying contain Al-rich, Fe 3+ -bearing dioctahedral smectite, with minor (3 wt %) quantities of ferripyrophyllite, interpreted as wind-blown detritus, found in candidate aeolian deposits. Our results suggest that dioctahedral smectite formed via near-surface chemical weathering driven by fluctuations in lake level and atmospheric infiltration, a process leading to the redistribution of nutrients and potentially influencing the cycling of gases that help regulate climate.

Clay mineral diversity and abundance in sedimentary rocks of Gale crater, Mars

PubMed Central

Chipera, Steve J.; Hazen, Robert M.; Horgan, Briony; Hogancamp, Joanna V.; Mangold, Nicolas; Morookian, John Michael; Morris, Richard V.; Vaniman, David T.; Yen, Albert S.

2018-01-01

Clay minerals provide indicators of the evolution of aqueous conditions and possible habitats for life on ancient Mars. Analyses by the Mars Science Laboratory rover Curiosity show that ~3.5–billion year (Ga) fluvio-lacustrine mudstones in Gale crater contain up to ~28 weight % (wt %) clay minerals. We demonstrate that the species of clay minerals deduced from x-ray diffraction and evolved gas analysis show a strong paleoenvironmental dependency. While perennial lake mudstones are characterized by Fe-saponite, we find that stratigraphic intervals associated with episodic lake drying contain Al-rich, Fe3+-bearing dioctahedral smectite, with minor (3 wt %) quantities of ferripyrophyllite, interpreted as wind-blown detritus, found in candidate aeolian deposits. Our results suggest that dioctahedral smectite formed via near-surface chemical weathering driven by fluctuations in lake level and atmospheric infiltration, a process leading to the redistribution of nutrients and potentially influencing the cycling of gases that help regulate climate. PMID:29881776

Investigating Interactions between the Silica and Carbon Cycles during Precipitation and Early Diagenesis of Authigenic Clay/Carbonate-Mineral Associations in the Carbonate Rock Record

NASA Astrophysics Data System (ADS)

McKenzie, J. A.; Francisca Martinez Ruiz, F.; Sanchez-Roman, M.; Anjos, S.; Bontognali, T. R. R.; Nascimento, G. S.; Vasconcelos, C.

2017-12-01

The study of authigenic clay/carbonate-mineral associations within carbonate sequences has important implications for the interpretation of scientific problems related with rock reservoir properties, such as alteration of potential porosity and permeability. More specifically, when clay minerals are randomly distributed within the carbonate matrix, it becomes difficult to predict reservoir characteristics. In order to understand this mineral association in the geological record, we have undertaken a comparative study of specially designed laboratory experiments with modern environments, where clay minerals have been shown to precipitate together with a range of carbonate minerals, including calcite, Mg-calcite and dolomite. Two modern dolomite-forming environments, the Coorong lakes, South Australia and Brejo do Espinho Rio de Janeiro, Brazil, were selected for this investigation. For comparative evaluation, enrichment microbial culture experiments, using natural pore water from Brejo do Espinho as the growth medium to promote mineral precipitation, were performed under both aerobic and anaerobic conditions. To establish the environmental parameters and biological processes facilitating the dual mineral association, the experimental samples have been compared with the natural minerals using HRTEM measurements. The results demonstrate that the clay and carbonate minerals apparently do not co-precipitate, but the precipitation of the different minerals in the same sample has probably occurred under different environmental conditions with variable chemistries, e.g., hypersalinity versus normal salinity resulting from the changing ratio of evaporation versus precipitation. Thus, the investigated mineral association is not a product of diagenetic processes but of sequential in situ precipitation processes related to changes in the silica and carbon availability. Implications for ancient carbonate formations will be presented and discussed in the context of a specific

Effect of organic matter properties, clay mineral type and thermal maturity on gas adsorption in organic-rich shale systems

USGS Publications Warehouse

Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Lewan, Mike; Sun, Xun; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

2013-01-01

A series of CH4 adsorption experiments on natural organic-rich shales, isolated kerogen, clay-rich rocks, and artificially matured Woodford Shale samples were conducted under dry conditions. Our results indicate that physisorption is a dominant process for CH4 sorption, both on organic-rich shales and clay minerals. The Brunauer–Emmett–Teller (BET) surface area of the investigated samples is linearly correlated with the CH4 sorption capacity in both organic-rich shales and clay-rich rocks. The presence of organic matter is a primary control on gas adsorption in shale-gas systems, and the gas-sorption capacity is determined by total organic carbon (TOC) content, organic-matter type, and thermal maturity. A large number of nanopores, in the 2–50 nm size range, were created during organic-matter thermal decomposition, and they significantly contributed to the surface area. Consequently, methane-sorption capacity increases with increasing thermal maturity due to the presence of nanopores produced during organic-matter decomposition. Furthermore, CH4 sorption on clay minerals is mainly controlled by the type of clay mineral present. In terms of relative CH4 sorption capacity: montmorillonite ≫ illite – smectite mixed layer > kaolinite > chlorite > illite. The effect of rock properties (organic matter content, type, maturity, and clay minerals) on CH4 adsorption can be quantified with the heat of adsorption and the standard entropy, which are determined from adsorption isotherms at different temperatures. For clay-mineral rich rocks, the heat of adsorption (q) ranges from 9.4 to 16.6 kJ/mol. These values are considerably smaller than those for CH4 adsorption on kerogen (21.9–28 kJ/mol) and organic-rich shales (15.1–18.4 kJ/mol). The standard entropy (Δs°) ranges from -64.8 to -79.5 J/mol/K for clay minerals, -68.1 to -111.3 J/mol/K for kerogen, and -76.0 to -84.6 J/mol/K for organic-rich shales. The affinity of CH4 molecules for sorption on organic matter

The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

NASA Astrophysics Data System (ADS)

Bristow, T.; Blake, D.; Bish, D. L.; Vaniman, D.; Ming, D. W.; Morris, R. V.; Chipera, S.; Rampe, E. B.; Farmer, J. D.; Treiman, A. H.; Downs, R.; Morrison, S.; Achilles, C.; Des Marais, D. J.; Crisp, J. A.; Sarrazin, P.; Morookian, J.; Grotzinger, J. P.; Team, M.

2013-12-01

The Mars Science Laboratory (MSL) Rover, Curiosity spent ~150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (~3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of ~20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at ~10A with a slight inflexion at ~12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and heating >60°C in the presence of water

The Alberhill and other clay deposits of Temescal Canyon, Riverside County, California

USGS Publications Warehouse

Daviess, Steven Norman; Bramlette, M.N.

1953-01-01

Clay is mined in open pits by several companies in the Alberhill district, and the refractory clays of relatively high alumina sediment are used largely for fire brick. The Alberhill Coal and Clay Company is the largest operator and has produced a little over 2,000,000 tons of clay, of which nearly half was the refractory type. The clay occurs at the contact of the lower Tertiary and the Mesozoic basement complex. The weathered surface of basement rocks includes much clay of high iron and low alumina content, and the better clay occurs in the basal Tertiary sediments. The clay deposits vary rather abruptly in thickness and quality, and only local lenses contain workable deposits. Structural deformation makes dips of 10 to 20 degrees common and the clay strata therefore pitch under excessive overburden in short distances. Extensive deposits of thick alluvial fan deposits cover the clay-bearing strata over most of the area, and add to the overburden problems. The apparent lack of clay deposits of good quality that would total several million tons of ore, and the geological conditions that would make exploration and mining difficult and expensive make this district unpromising.

Maine Pseudotachylyte Localities and the Role of Host Rock Anisotropy in Fault Zone Development and Frictional Melting

NASA Astrophysics Data System (ADS)

Swanson, M. T.

2004-12-01

Three brittle strike-slip fault localities in coastal Maine have developed pseudotachylyte fault veins, injection veins and other reservoir structures in a variety of host rocks where the pre-existing layering can serve as a controlling fabric for brittle strike-slip reactivation. Host rocks with a poorly-oriented planar anisotropy at high angles to the shear direction will favor the development of R-shears in initial en echelon arrays as seen in the Two Lights and Richmond Island Fault Zones of Cape Elizabeth that cut gently-dipping phyllitic quartzites. These en echelon R-shears grow to through-going faults with the development of P-shear linkages across the dominantly contractional stepovers in the initial arrays. Pseudotachylyte on these faults is very localized, typically up to 1-2 mm in thickness and is restricted to through-going fault segments, P-shear linkages and some sidewall ripouts. Overall melt production is limited by the complex geometry of the multi-fault array. Host rocks with a favorably-oriented planar anisotropy for reactivation in brittle shear, however, preferentially develop a multitude of longer, non-coplanar layer-parallel fault segments. Pseudotachylyte in the newly-discovered Harbor Island Fault Zone in Muscongus Bay is developed within vertical bedding on regional upright folds with over 50 individual layer-parallel single-slip fault veins, some of which can be traced for over 40 meters along strike. Many faults show clear crosscuts of pre-existing quartz veins that indicate a range of coseismic displacements of 0.23-0.53 meters yielding fault vein widths of a few mm and dilatant reservoirs up to 2 cm thick. Both vertical and rare horizontal lateral injection veins can be found in the adjoining wall rock up to 0.7 cm thick and 80 cm in length. The structure of these faults is simple with minor development of splay faults, sidewall ripouts and strike-slip duplexes. The prominent vertical flow layering within the mylonite gneisses of

Mars, clays and the origins of life

NASA Technical Reports Server (NTRS)

Hartman, Hyman

1989-01-01

To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

Comparative study of Se oxyanions retention on three argillaceous rocks: Upper Toarcian (Tournemire, France), Black Shales (Tournemire, France) and Opalinus Clay (Mont Terri, Switzerland).

PubMed

Frasca, B; Savoye, S; Wittebroodt, C; Leupin, O X; Michelot, J-L

2014-01-01

A comparative study of selenium oxyanion sorption was carried out by means of batch sorption experiments on three argillaceous rocks that differ in their mineralogical compositions and textural properties. The results show no selenate (Se(VI)) sorption onto the argillaceous rocks after 60 days, but clear sorption of selenite (Se(IV)), the extent being closely related to the initial Se(IV) concentration. At the lowest concentration ([Se(IV)]eq < 10(-8) mol L(-1)), the ranking of rock affinity for Se(IV) is Black Shales > Opalinus Clay (OPA) > Upper Toarcian, with Rd values of 910 ± 70, 600 ± 65 and 470 ± 70 mL g(-1) respectively. The Se(IV) sorption isotherms acquired for the three argillaceous rocks can be reproduced well by means of Langmuir formalism, particularly with a two-site Langmuir model. The comparison of the Se(IV) sorption isotherms obtained for these three rocks led to identification of pyrite associated with natural organic matter (NOM) as one of the main phases involved in selenium retention. While the desorption results suggested a significant Se(IV) reduction in the Upper Toarcian samples, the reversible sorption shown on the Black Shales and OPA samples was correlated with a sulfate increase, symptomatic of surface oxidation of pyrite which could limit the Se(IV) reduction in favor of sorption. Copyright © 2013 Elsevier Ltd. All rights reserved.

California Bearing Ratio (CBR) test on stabilization of clay with lime addition

NASA Astrophysics Data System (ADS)

Hastuty, I. P.; Roesyanto; Limbong, M. N.; Oberlyn, S. J.

2018-02-01

Clay is a type of soil with particles of certain minerals giving plastic properties when mixed with water. Soil has an important role in a construction, besides as a building material in a wide variety of civil engineering works, soil is also used as supporting foundation of the building. Basic properties of clay are rock-solid in dry and plastic with medium water content. In high water content, clay becomes sticky like (cohesive) and soften. Therefore, clay stabilization is necessary to repair soil’s mechanical properties. In this research, lime is use as a stabilizer that contains the Ca+ element to bond bigger particles. Lime used is slaked lime Ca(OH)2. Clay used has liquid limitation (LL) value of 47.33%, plasticity index of 29.88% and CBR value 6.29. The results explain about 10% lime mixture variation gives the optimum stabilized clay with CBR value of 8.75%.

Rock Physics and Petrographic Parameters Relationship Within Siliciclastic Rocks: Quartz Sandstone Outcrop Study Case

NASA Astrophysics Data System (ADS)

Syafriyono, S.; Caesario, D.; Swastika, A.; Adlan, Q.; Syafri, I.; Abdurrokhim, A.; Mardiana, U.; Mohamad, F.; Alfadli, M. K.; Sari, V. M.

2018-03-01

Rock physical parameters value (Vp and Vs) is one of fundamental aspects in reservoir characterization as a tool to detect rock heterogenity. Its response is depend on several reservoir conditions such as lithology, pressure and reservoir fluids. The value of Vp and Vs is controlled by grain contact and contact stiffness, a function of clay mineral content and porosity also affected by mineral composition. The study about Vp and Vs response within sandstone and its relationship with petrographic parameters has become important to define anisotrophy of reservoir characteristics distribution and could give a better understanding about local diagenesis that influence clastic reservoir properties. Petrographic analysis and Vp-Vs calculation was carried out to 12 core sample which is obtained by hand-drilling of the outcrop in Sukabumi area, West Java as a part of Bayah Formation. Data processing and interpretation of sedimentary vertical succession showing that this outcrop comprises of 3 major sandstone layers indicating fluvial depositional environment. As stated before, there are 4 petrographic parameters (sorting, roundness, clay mineral content, and grain contact) which are responsible to the differences of shear wave and compressional wave value in this outcrop. Lithology with poor-sorted and well- roundness has Vp value lower than well-sorted and poor-roundness (sub-angular) grain. For the sample with high clay content, Vp value is ranging from 1681 to 2000 m/s and could be getting high until 2190 to 2714 m/s in low clay content sample even though the presence of clay minerals cannot be defined neither as matrix nor cement. The whole sample have suture grain contact indicating telogenesis regime whereas facies has no relationship with Vp and Vs value because of the different type of facies show similar petrographic parameters after diagenesis.

Vein deposits hosted by plutonic rocks in the Croesus Stock and Hailey gold belt mineralized areas, Blaine County, Idaho

USGS Publications Warehouse

Worl, Ronald G.; Lewis, Reed S.

2001-01-01

Mineral deposits in the Croesus and Hailey gold belt mineralized areas in Blaine County, south-central Idaho, are preciousand base-metal quartz veins that are part of a family of vein deposits spatially and temporally associated with the Idaho batholith. Historic production from these veins has been mainly gold and silver. Host rocks are older border phase plutons of the Idaho batholith that are characterized by more potassium and less sodium as compared to rocks from the main body of the batholith to the west. Host structures are reverse faults that have moderate to shallow dips to the northeast and high-angle normal faults that also strike northwest. The veins are characterized by several generations of quartz and generally sparse sulfide minerals; gold is associated with late-stage comb quartz. The precious-metal ore bodies are in a series of shoots, each of which is as much as 8 ft in width, 400 ft in breadth, and 1,000 ft in pitch length.

Clay minerals trap hydrogen in the Earth's crust: Evidence from the Cigar Lake uranium deposit, Athabasca

NASA Astrophysics Data System (ADS)

Truche, Laurent; Joubert, Gilles; Dargent, Maxime; Martz, Pierre; Cathelineau, Michel; Rigaudier, Thomas; Quirt, David

2018-07-01

Hydrogen (H2)-rich fluids are observed in a wide variety of geologic settings including gas seeps in serpentinized ultramafic rocks, sub-seafloor hydrothermal vents, fracture networks in crystalline rocks from continental and oceanic crust, and volcanic gases. Natural hydrogen sources can sustain deep microbial ecosystems, induce abiotic hydrocarbons synthesis and trigger the formation of prebiotic organic compounds. However, due to its extreme mobility and small size, hydrogen is not easily trapped in the crust. If not rapidly consumed by redox reactions mediated by bacteria or suitable mineral catalysts it diffuses through the rocks and migrates toward the surface. Therefore, H2 is not supposed to accumulate in the crust. We challenge this view by demonstrating that significant amount of H2 may be adsorbed by clay minerals and remain trapped beneath the surface. Here, we report for the first time H2 content in clay-rich rocks, mainly composed of illite, chlorite, and kaolinite from the Cigar Lake uranium ore deposit (northern Saskatchewan, Canada). Thermal desorption measurements reveal that H2 is enriched up to 500 ppm (i.e. 0.25 mol kg-1 of rock) in these water-saturated rocks having a very low total organic content (<0.5 wt%). Such hydrogen uptake is comparable and even exceeds adsorbed methane capacities reported elsewhere for pure clay minerals or shales. Sudoite (Al-Mg di-trioctahedral chlorite) is probably the main mineral responsible for H2 adsorption in the present case. The presence of multiple binding sites in interlinked nanopores between crystal layers of illite-chlorite particles offers the ideal conditions for hydrogen sorption. We demonstrate that 4 to 17% of H2 produced by water radiolysis over the 1.4-Ga-lifetime of the Cigar Lake uranium ore deposit has been trapped in the surrounding clay alteration haloes. As a result, sorption processes on layered silicates must not be overlooked as they may exert an important control on the fate and

Heterogeneity in friction strength of an active fault by incorporation of fragments of the surrounding host rock

NASA Astrophysics Data System (ADS)

Kato, Naoki; Hirono, Tetsuro

2016-07-01

To understand the correlation between the mesoscale structure and the frictional strength of an active fault, we performed a field investigation of the Atera fault at Tase, central Japan, and made laboratory-based determinations of its mineral assemblages and friction coefficients. The fault zone contains a light gray fault gouge, a brown fault gouge, and a black fault breccia. Samples of the two gouges contained large amounts of clay minerals such as smectite and had low friction coefficients of approximately 0.2-0.4 under the condition of 0.01 m s-1 slip velocity and 0.5-2.5 MP confining pressure, whereas the breccia contained large amounts of angular quartz and feldspar and had a friction coefficient of 0.7 under the same condition. Because the fault breccia closely resembles the granitic rock of the hangingwall in composition, texture, and friction coefficient, we interpret the breccia as having originated from this protolith. If the mechanical incorporation of wall rocks of high friction coefficient into fault zones is widespread at the mesoscale, it causes the heterogeneity in friction strength of fault zones and might contribute to the evolution of fault-zone architectures.

Paleoenvironmental Implications of Clay Minerals at Yellowknife Bay, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Bristow, Thomas F.; Blake, David F.

2014-01-01

The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx. 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx. 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at approx. 10A with a slight inflexion at approx. 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and

Microbe-Clay Mineral Reactions and Characterization Techniques

NASA Astrophysics Data System (ADS)

Dong, H.; Zhang, G.; Ji, S.; Jaisi, D.; Kim, J.

2008-12-01

Clays and clay minerals are ubiquitous in soils, sediments, and sedimentary rocks. They play an important role in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. The changes in the oxidation state of the structural iron in clay minerals, in part, control their physical and chemical properties in natural environments, such as clay particle flocculation, dispersion, swelling, hydraulic conductivity, surface area, cation and anion exchange capacity, and reactivity towards organic and inorganic contaminants. The structural ferric iron [Fe(III)] in clay minerals can be reduced either chemically or biologically. Many different chemical reductants have been tried, but the most commonly used agent is dithionite. Biological reductants are bacteria, including dissimilatory iron reducing prokaryotes (DIRP) and sulfate-reducing bacteria (SRB). A wide variety of DIRP have been used to reduce ferric iron in clay minerals, including mesophilic, thermophilic, and hyperthermophilic prokaryotes. Multiple clay minerals have been used for microbial reduction studies, including smectite, nontronite (iron-rich smectite variety), illite, illite/smectite, chlorite, and their various mixtures. All these clay minerals are reducible by microorganisms under various conditions with smectite (nontronite) being the most reducible. The reduction extent and rate of ferric iron in clay minerals are measured by wet chemistry, and the reduced clay mineral products are typically characterized with chemical methods, X-ray diffraction, scanning and transmission electron microscopy, Mössbauer spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), UV-vis spectroscopy, and synchrotron-based techniques (such as EXAFS). Microbially reduced smectites (nontronites) have been found to be reactive in reducing a variety of organic and inorganic contaminants. Degradable organic contaminants include pesticides

Dynamic mechanical properties and anisotropy of synthetic shales with different clay minerals under confining pressure

NASA Astrophysics Data System (ADS)

Gong, Fei; Di, Bangrang; Wei, Jianxin; Ding, Pinbo; Shuai, Da

2018-03-01

The presence of clay minerals can alter the elastic behaviour of reservoir rocks significantly as the type of clay minerals, their volume and distribution, and their orientation control the shale's intrinsic anisotropic behaviours. Clay minerals are the most abundant materials in shale, and it has been proven extremely difficult to measure the elastic properties of natural shale by means of a single variable (in this case, the type of clay minerals), due to the influences of multiple factors, including water, TOC content and complex mineral compositions. We used quartz, clay (kaolinite, illite and smectite), carbonate and kerogen extract as the primary materials to construct synthetic shale with different clay minerals. Ultrasonic experiments were conducted to investigate the anisotropy of velocity and mechanical properties in dry synthetic and natural shale as a function of confining pressure. Velocities in synthetic shale are sensitive to the type of clay minerals, possibly due to the different structures of the clay minerals. The velocities increase with confining pressure and show higher rate of velocity increase at low pressures, and P-wave velocity is usually more sensitive than S-wave velocity to confining pressure according to our results. Similarly, the dynamic Young's modulus and Poisson's ratio increase with applied pressure, and the results also reveal that E11 is always larger than E33 and ν31 is smaller than ν12. Velocity and mechanical anisotropy decrease with increasing stress, and are sensitive to stress and the type of clay minerals. However, the changes of mechanical anisotropy with applied stress are larger compared with the velocity anisotropy, indicating that mechanical properties are more sensitive to the change of rock properties.

Newly discovered sediment rock-hosted disseminated gold deposits in the People's Republic of China

USGS Publications Warehouse

Cunningham, Charles G.; Ashley, Roger P.; Chou, I. -Ming; Huang, Zushu; Chaoyuan, Wan; Li, Wenkang

1988-01-01

Five deposits discovered in Guizhou Province, Yata, Getang, Sanchahe, Ceyang, and Banqi are described for the first time in Western literature. The deposits have geologic features and geochemical signatures that are remarkably similar to those of sedimentary rock-hosted precious metal deposits in the United States. The sizes of the deposits are as yet undetermined, but they each contain significant reserves at average grades of 4 to 5 g of gold per metric ton. Exploration and drilling are in progress at all of the deposits, and other areas where the geologic setting and geochemical anomalies are similar are being tested.

Mineralogical, chemical and K-Ar isotopic changes in Kreyenhagen Shale whole rocks and <2 µm clay fractions during natural burial and hydrous-pyrolysis experimental maturation

USGS Publications Warehouse

Clauer, Norbert; Lewan, Michael D.; Dolan, Michael P.; Chaudhuri, Sambhudas; Curtis, John B.

2014-01-01

Large amounts of smectite layers in the illite–smectite mixed layers of the pyrolyzed outcrop <2 μm fraction remain during thermal experiments, especially above 310 °C. With no illitization detected above 310 °C, smectite appears to have inhibited rather than promoted generation of expelled oil from decomposition of bitumen. This hindrance is interpreted to result from bitumen impregnating the smectite interlayer sites and rock matrix. Bitumen remains in the <2 μm fraction despite leaching with H2O2. Its presence in the smectite interlayers is apparent by the inability of the clay fraction to fully expand or collapse once bitumen generation from the thermal decomposition of the kerogen is completed, and by almost invariable K–Ar ages confirming for the lack of any K supply and/or radiogenic 40Ar removal. This suggests that once bitumen impregnates the porosity of a progressively maturing source rock, the pore system is no longer wetted by water and smectite to illite conversion ceases. Experimental attempts to evaluate the smectite conversion to illite should preferentially use low-TOC rocks to avoid inhibition of the reaction by bitumen impregnation.

The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

NASA Technical Reports Server (NTRS)

Bristow, Thomas; Blake, David; Bish, David L.; Vaniman, David; Ming, Douglas W.; Morris, Richard V.; Chipera, Steve; Rampe, Elizabeth B.; Farmer, Jack, D.; Treiman, Allan H;

Evaluation of the predictive capability of coupled thermo-hydro-mechanical models for a heated bentonite/clay system (HE-E) in the Mont Terri Rock Laboratory

DOE PAGES

Garitte, B.; Shao, H.; Wang, X. R.; ...

2017-01-09

Process understanding and parameter identification using numerical methods based on experimental findings are a key aspect of the international cooperative project DECOVALEX. Comparing the predictions from numerical models against experimental results increases confidence in the site selection and site evaluation process for a radioactive waste repository in deep geological formations. In the present phase of the project, DECOVALEX-2015, eight research teams have developed and applied models for simulating an in-situ heater experiment HE-E in the Opalinus Clay in the Mont Terri Rock Laboratory in Switzerland. The modelling task was divided into two study stages, related to prediction and interpretation ofmore » the experiment. A blind prediction of the HE-E experiment was performed based on calibrated parameter values for both the Opalinus Clay, that were based on the modelling of another in-situ experiment (HE-D), and modelling of laboratory column experiments on MX80 granular bentonite and a sand/bentonite mixture .. After publication of the experimental data, additional coupling functions were analysed and considered in the different models. Moreover, parameter values were varied to interpret the measured temperature, relative humidity and pore pressure evolution. The analysis of the predictive and interpretative results reveals the current state of understanding and predictability of coupled THM behaviours associated with geologic nuclear waste disposal in clay formations.« less

Evaluation of the predictive capability of coupled thermo-hydro-mechanical models for a heated bentonite/clay system (HE-E) in the Mont Terri Rock Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garitte, B.; Shao, H.; Wang, X. R.

Process understanding and parameter identification using numerical methods based on experimental findings are a key aspect of the international cooperative project DECOVALEX. Comparing the predictions from numerical models against experimental results increases confidence in the site selection and site evaluation process for a radioactive waste repository in deep geological formations. In the present phase of the project, DECOVALEX-2015, eight research teams have developed and applied models for simulating an in-situ heater experiment HE-E in the Opalinus Clay in the Mont Terri Rock Laboratory in Switzerland. The modelling task was divided into two study stages, related to prediction and interpretation ofmore » the experiment. A blind prediction of the HE-E experiment was performed based on calibrated parameter values for both the Opalinus Clay, that were based on the modelling of another in-situ experiment (HE-D), and modelling of laboratory column experiments on MX80 granular bentonite and a sand/bentonite mixture .. After publication of the experimental data, additional coupling functions were analysed and considered in the different models. Moreover, parameter values were varied to interpret the measured temperature, relative humidity and pore pressure evolution. The analysis of the predictive and interpretative results reveals the current state of understanding and predictability of coupled THM behaviours associated with geologic nuclear waste disposal in clay formations.« less

Hard-rock GMPEs versus Vs30-Kappa Host-to-Target Adjustment Techniques : Why so Large Differences in High Frequency Hard-Rock Motion ?

NASA Astrophysics Data System (ADS)

Bard, P. Y.; Laurendeau, A.; Hollender, F.; Perron, V.; Hernandez, B.; Foundotos, L.

2016-12-01

Assessment of local seismic hazard on hard rock sites (1000 < VS30 < 3000 m/s) is needed either for installations built on such hard rock, or as a reference motion for site response computation. Empirical ground motion prediction equations (GMPEs) are the traditional basis for estimating ground motion, but most of them are poorly constrained for VS30 larger than 1000 m/s. The presently used approach for estimating hard rock hazard consists of "host-to-target" adjustment techniques (HTTA) based on VS30 and κ0 values. Recent studies have investigated alternative methods to estimate reference motions on very hard rock through an original processing of the Japanese KiK-net recordings from stiff sites (500 < VS30 < 1350 m/s). The pairs of recordings at surface and depth, together with the knowledge of the velocity profile, allowed to derive two sets of "virtual" outcropping, hard-rock motion data for sites having velocities in the range [1000 - 3000 m/s]. The corrections are based either on a transformation of deep, within-motion to outcropping motion, or on a deconvolution of surface recordings using the velocity profile and 1D simulation, which has been performed both in the response spectrum and Fourier domains. Each of these virtual "outcropping hard-rock motion" data sets has then been used to derive GMPEs with simple functional forms, using as site condition proxy the S-wave velocity at depth (VSDH), ranging from 1000 to 3000 m/s. Both sets provide very similar predictions, which are much smaller at high frequencies (f > 10 Hz) than those estimated with the traditional HTTA technique - by a factor up to 3-4,. These differences decrease for decreasing frequency, and become negligible at low frequency (f < 1 Hz). The main focus will be to discuss the possible reasons of such differences, in relation with the implicit or explicit assumptions of either approach. Our present interpretation is related to the existence of a significant, high-frequency amplification on

Identification and characterization of hydrothermally altered zones in granite by combining synthetic clay content logs with magnetic mineralogical investigations of drilled rock cuttings

NASA Astrophysics Data System (ADS)

Meller, Carola; Kontny, Agnes; Kohl, Thomas

2014-10-01

Clay minerals as products of hydrothermal alteration significantly influence the hydraulic and mechanical properties of crystalline rock. Therefore, the localization and characterization of alteration zones by downhole measurements is a great challenge for the development of geothermal reservoirs. The magnetite bearing granite of the geothermal site in Soultz-sous-Forêts (France) experienced hydrothermal alteration during several tectonic events and clay mineral formation is especially observed in alteration halos around fracture zones. During the formation of clay minerals, magnetite was oxidized into hematite, which significantly reduces the magnetic susceptibility of the granite from ferrimagnetic to mostly paramagnetic values. The aim of this study was to find out if there exists a correlation between synthetic clay content logs (SCCLs) and measurements of magnetic susceptibility on cuttings in the granite in order to characterize their alteration mineralogy. Such a correlation has been proven for core samples of the EPS1 reference well. SCCLs were created from gamma ray and fracture density logs using a neural network. These logs can localize altered fracture zones in the GPK1-4 wells, where no core material is available. Mass susceptibility from 261 cutting samples of the wells GPK1-GPK4 was compared with the neural network derived synthetic logs. We applied a combination of temperature dependent magnetic susceptibility measurements with optical and electron microscopy, and energy dispersive X-ray spectroscopy to discriminate different stages of alteration. We found, that also in the granite cuttings an increasing alteration grade is characterized by an advancing oxidation of magnetite into hematite and a reduction of magnetic susceptibility. A challenge to face for the interpretation of magnetic susceptibility data from cuttings material is that extreme alteration grades can also display increased susceptibilities due to the formation of secondary magnetite

Origin and evolution of phyllosilicate deformation bands in the poorly lithified sandstones of the Rio do Peixe Basin, NE Brazil

NASA Astrophysics Data System (ADS)

Nogueira, Francisco; Nicchio, Matheus; Balsamo, Fabrizio; Bezerra, Francisco; Souza, Jorge; Carvalho, Bruno; Storti, Fabrizio

2017-04-01

In this work we describe the genetic processes and the microstructural evolution of phylossilicate deformation bands developed in poorly lithified, high porosity sandstones of the Rio do Peixe Basin, Northeast Brazil. The studied deformation bands occur in damage zones of NE-SW and NW-SE transtensional faults that exhibit well developed anastomosed clusters, with a thickness varying from tens of centimeters to 1 meter. The Host rocks are arkosic to lithic arkosic coarse sandstones to fine conglomerate and with less than 1% of clay content in the matrix. Based on (i) field observations, (ii) clay amount in deformation band cores and (iii) clay mineral arrangements in deformation bands cores, we identified two types of phyllosilicate deformation bands: (1) clay smearing deformation bands and (2) phyllosilicate deformation bands formed by clay authigenesis. The former occur only in fault zones that cut across clay-rich layers and are characterized by 45-50% of clay content. Single element chemical analysis indicates that the composition of clay minerals in clay smearing deformation bands is similar to that of clay-rich layers in the host rocks. The dominant deformation mechanism is particulate flow, which produces preferential alignments of grains and clay minerals. Only subordinate cataclasis occurs. Based on microstructural fabrics, three evolutionary stages can be identified for phyllosilicate deformation bands formed by clay authigenesis. The first one is characterized by preferentially cataclasis and weathering of feldspars. Clay concentration is relatively low, reaching 15-20%, with preferential concentration where crushed feldspar abundance is higher. The second stage is characterized by clay migration within deformation bands, to form continuous films with more than 20-25% of clay concentration. In the last stage clay mineral fabric re-organization occurs, forming well a developed S-C foliation. Clay concentration exceeds 35%. Single element chemical analysis

Life in a rock pool: Radiation and population genetics of myxozoan parasites in hosts inhabiting restricted spaces.

PubMed

Bartošová-Sojková, Pavla; Lövy, Alena; Reed, Cecile C; Lisnerová, Martina; Tomková, Tereza; Holzer, Astrid S; Fiala, Ivan

2018-01-01

Intertidal rock pools where fish and invertebrates are in constant close contact due to limited space and water level fluctuations represent ideal conditions to promote life cycles in parasites using these two alternate hosts and to study speciation processes that could contribute to understanding the roles of parasitic species in such ecosystems. Gall bladder and liver samples from five clinid fish species (Blenniiformes: Clinidae) were morphologically and molecularly examined to determine the diversity, prevalence, distribution and host specificity of Ceratomyxa parasites (Cnidaria: Myxozoa) in intertidal habitats along the coast of South Africa. Phylogenetic relationships of clinid ceratomyxids based on the SSU rDNA, LSU rDNA and ITS regions were assessed additionally to the investigation of population genetic structure of Ceratomyxa cottoidii and subsequent comparison with the data known from type fish host Clinus cottoides. Seven Ceratomyxa species including previously described Ceratomyxa dehoopi and C. cottoidii were recognized in clinids. They represent a diverse group of rapidly evolving, closely related species with a remarkably high prevalence in their hosts, little host specificity and frequent concurrent infections, most probably as a result of parasite radiation after multiple speciation events triggered by limited host dispersal within restricted spaces. C. cottoidii represents the most common clinid parasite with a population structure characterized by young expanding populations in the south west and south east coast and by older populations in equilibrium on the west coast of its distribution. Parasite and fish host population structures show overlapping patterns and are very likely affected by similar oceanographic barriers possibly due to reduced host dispersal enhancing parasite community differentiation. While fish host specificity had little impact on parasite population structure, the habitat preference of the alternate invertebrate host as

Life in a rock pool: Radiation and population genetics of myxozoan parasites in hosts inhabiting restricted spaces

PubMed Central

Reed, Cecile C.; Lisnerová, Martina; Tomková, Tereza; Holzer, Astrid S.; Fiala, Ivan

2018-01-01

Introduction Intertidal rock pools where fish and invertebrates are in constant close contact due to limited space and water level fluctuations represent ideal conditions to promote life cycles in parasites using these two alternate hosts and to study speciation processes that could contribute to understanding the roles of parasitic species in such ecosystems. Material and methods Gall bladder and liver samples from five clinid fish species (Blenniiformes: Clinidae) were morphologically and molecularly examined to determine the diversity, prevalence, distribution and host specificity of Ceratomyxa parasites (Cnidaria: Myxozoa) in intertidal habitats along the coast of South Africa. Phylogenetic relationships of clinid ceratomyxids based on the SSU rDNA, LSU rDNA and ITS regions were assessed additionally to the investigation of population genetic structure of Ceratomyxa cottoidii and subsequent comparison with the data known from type fish host Clinus cottoides. Results and discussion Seven Ceratomyxa species including previously described Ceratomyxa dehoopi and C. cottoidii were recognized in clinids. They represent a diverse group of rapidly evolving, closely related species with a remarkably high prevalence in their hosts, little host specificity and frequent concurrent infections, most probably as a result of parasite radiation after multiple speciation events triggered by limited host dispersal within restricted spaces. C. cottoidii represents the most common clinid parasite with a population structure characterized by young expanding populations in the south west and south east coast and by older populations in equilibrium on the west coast of its distribution. Parasite and fish host population structures show overlapping patterns and are very likely affected by similar oceanographic barriers possibly due to reduced host dispersal enhancing parasite community differentiation. While fish host specificity had little impact on parasite population structure, the

Wind Carved Rock

NASA Image and Video Library

2016-10-19

The distinctively fluted surface and elongated hills in this image in Medusae Fossae are caused by wind erosion of a soft fine-grained rock. Called yardangs, these features are aligned with the prevailing wind direction. This wind direction would have dominated for a very long time to carve these large-scale features into the exposed rock we see today. Yardangs not only reveal the strength and direction of historic winds, but also reveal something of the host rock itself. Close inspection by HiRISE shows an absence of boulders or rubble, especially along steep yardang cliffs and buttresses. The absence of rubble and the scale of the yardangs tells us that the host rock consists only of weakly cemented fine granules in tens of meters or more thick deposits. Such deposits could have come from extended settling of volcanic ash, atmospheric dust, or accumulations of wind deposited fine sands. After a time these deposits became cemented and cohesive, illustrated by the high standing relief and exposed cliffs. http://photojournal.jpl.nasa.gov/catalog/PIA21111

Effect of Hydrothermal Alteration on Rock Properties in Active Geothermal Setting

NASA Astrophysics Data System (ADS)

Mikisek, P.; Bignall, G.; Sepulveda, F.; Sass, I.

2012-04-01

Hydrothermal alteration records the physical-chemical changes of rock and mineral phases caused by the interaction of hot fluids and wall rock, which can impact effective permeability, porosity, thermal parameters, rock strength and other rock properties. In this project, an experimental approach has been used to investigate the effects of hydrothermal alteration on rock properties. A rock property database of contrastingly altered rock types and intensities has been established. The database details horizontal and vertical permeability, porosity, density, thermal conductivity and thermal heat capacity for ~300 drill core samples from wells THM12, THM13, THM14, THM17, THM18, THM22 and TH18 in the Wairakei-Tauhara geothermal system (New Zealand), which has been compared with observed hydrothermal alteration type, rank and intensity obtained from XRD analysis and optical microscopy. Samples were selected from clay-altered tuff and intercalated siltstones of the Huka Falls Formation, which acts as a cap rock at Wairakei-Tauhara, and tuffaceous sandstones of the Waiora Formation, which is a primary reservoir-hosting unit for lateral and vertical fluid flows in the geothermal system. The Huka Falls Formation exhibits argillic-type alteration of varying intensity, while underlying Waiora Formations exhibits argillic- and propylithic-type alteration. We plan to use a tempered triaxial test cell at hydrothermal temperatures (up to 200°C) and pressures typical of geothermal conditions, to simulate hot (thermal) fluid percolation through the rock matrix of an inferred "reservoir". Compressibility data will be obtained under a range of operating (simulation reservoir) conditions, in a series of multiple week to month-long experiments that will monitor change in permeability and rock strength accompanying advancing hydrothermal alteration intensity caused by the hot brine interacting with the rock matrix. We suggest, our work will provide new baseline information concerning

10 CFR 960.4-2-3 - Rock characteristics.

Code of Federal Regulations, 2010 CFR

2010-01-01

... thermal, chemical, mechanical, and radiation stresses expected to be induced by repository construction, operation, and closure and by expected interactions among the waste, host rock, ground water, and engineered... repository construction, operation, or closure or by interactions among the waste, host rock, ground water...

10 CFR 960.4-2-3 - Rock characteristics.

Code of Federal Regulations, 2011 CFR

2011-01-01

... thermal, chemical, mechanical, and radiation stresses expected to be induced by repository construction, operation, and closure and by expected interactions among the waste, host rock, ground water, and engineered... repository construction, operation, or closure or by interactions among the waste, host rock, ground water...

Mineralogical, chemical and K-Ar isotopic changes in Kreyenhagen Shale whole rocks and <2 μm clay fractions during natural burial and hydrous-pyrolysis experimental maturation

NASA Astrophysics Data System (ADS)

Clauer, N.; Lewan, M. D.; Dolan, M. P.; Chaudhuri, S.; Curtis, J. B.

2014-04-01

Progressive maturation of the Eocene Kreyenhagen Shale from the San Joaquin Basin of California was studied by combining mineralogical and chemical analyses with K-Ar dating of whole rocks and <2 μm clay fractions from naturally buried samples and laboratory induced maturation by hydrous pyrolysis of an immature outcrop sample. The K-Ar age decreases from 89.9 ± 3.9 and 72.4 ± 4.2 Ma for the outcrop whole rock and its <2 μm fraction, respectively, to 29.7 ± 1.5 and 21.0 ± 0.7 Ma for the equivalent materials buried to 5167 m. The natural maturation does not produce K-Ar ages in the historical sense, but rather K/Ar ratios of relative K and radiogenic 40Ar amounts resulting from a combined crystallization of authigenic and alteration of initial detrital K-bearing minerals of the rocks. The Al/K ratio of the naturally matured rocks is essentially constant for the entire depth sequence, indicating that there is no detectable variation in the crystallo-chemical organization of the K-bearing alumino-silicates with depth. No supply of K from outside of the rock volumes occurred, which indicates a closed-system behavior for it. Conversely, the content of the total organic carbon (TOC) content decreases significantly with burial, based on the progressive increasing Al/TOC ratio of the whole rocks. The initial varied mineralogy and chemistry of the rocks and their <2 μm fractions resulting from differences in detrital sources and depositional settings give scattered results that homogenize progressively during burial due to increased authigenesis, and concomitant increased alteration of the detrital material. Hydrous pyrolysis was intended to alleviate the problem of mineral and chemical variations in initially deposited rocks of naturally matured sequences. However, experiments on aliquots from thermally immature Kreyenhagen Shale outcrop sample did not mimic the results from naturally buried samples. Experiments conducted for 72 h at temperatures from 270 to 365 �

Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars

NASA Astrophysics Data System (ADS)

Bishop, Janice L.; Fairén, Alberto G.; Michalski, Joseph R.; Gago-Duport, Luis; Baker, Leslie L.; Velbel, Michael A.; Gross, Christoph; Rampe, Elizabeth B.

2018-03-01

The ancient rock record for Mars has long been at odds with climate modelling. The presence of valley networks, dendritic channels and deltas on ancient terrains points towards running water and fluvial erosion on early Mars1, but climate modelling indicates that long-term warm conditions were not sustainable2. Widespread phyllosilicates and other aqueous minerals on the Martian surface3-6 provide additional evidence that an early wet Martian climate resulted in surface weathering. Some of these phyllosilicates formed in subsurface crustal environments5, with no association with the Martian climate, while other phyllosilicate-rich outcrops exhibit layered morphologies and broad stratigraphies7 consistent with surface formation. Here, we develop a new geochemical model for early Mars to explain the formation of these clay-bearing rocks in warm and wet surface locations. We propose that sporadic, short-term warm and wet environments during a generally cold early Mars enabled phyllosilicate formation without requiring long-term warm and wet conditions. We conclude that Mg-rich clay-bearing rocks with lateral variations in mixed Fe/Mg smectite, chlorite, talc, serpentine and zeolite occurrences formed in subsurface hydrothermal environments, whereas dioctahedral (Al/Fe3+-rich) smectite and widespread vertical horizonation of Fe/Mg smectites, clay assemblages and sulphates formed in variable aqueous environments on the surface of Mars. Our model for aluminosilicate formation on Mars is consistent with the observed geological features, diversity of aqueous mineralogies in ancient surface rocks and state-of-the-art palaeoclimate scenarios.

Hydroxyapatite clay for gap filling and adequate bone ingrowth.

PubMed

Maruyama, M; Terayama, K; Ito, M; Takei, T; Kitagawa, E

1995-03-01

In uncemented total hip arthroplasty, a complete filling of the gap between femoral prosthesis and the host bone is difficult and defects would remain, because the anatomy of the reamed intramedullary canal cannot fit the prosthesis. Therefore, it seems practical to fill the gap with a clay containing hydroxyapatite (HA), which has an osteoconductive character. The clay (HA clay) is made by mixing HA granules (size 0.1 mm or more) having a homogeneous pore distribution and a porosity of 35-48 vol%, and a viscous substance such as a saline solution of sodium alginate (SSSA). In the first experiment, the ratio of HA granules and sodium alginate in SSSA is set for the same handling properties of HA clay and polymethylmethacrylate bone cement (standard viscosity) before hardening. As a result, the ratio is set for 55 wt% of HA in the clay and 12.5 wt% of sodium alginate in SSSA (i.e., HA:sodium alginate:saline solution = 9.8:1:7). In the second study, the gap between the femoral stem and bone model is completely filled with HA clay. However, the gap is not filled only with HA granules or HA granules mixed with saline solution. In the third animal experiment, using an unloaded model, histology shows that HA clay has an osteoconductive property bridging the gap between the implant and the cortical bone without any adverse reaction. HA clay is considered a useful biomaterial to fill the gap with adequate bone ingrowth.

Microbial Impacts on Clay Mineral Transformation and Reactivity

NASA Astrophysics Data System (ADS)

Dong, H.; Jaisi, D.; Fredrickson, J.; Plymale, A.

2006-05-01

Clays and clay minerals are ubiquitous in soils, sedimentary rocks, and pelagic oozes. They play important roles in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. Iron is a major constituent in clay minerals, and its mobility and stability in different environmental processes is, in part, controlled by the oxidation state. Recent studies have shown that biological reduction of structural Fe(III) in clay minerals can change the physical and chemical properties of clay minerals, such as swelling, cation exchange and fixation capacity, specific surface area, color, and magnetic exchange interactions. As a result of biological reduction of Fe(III), clay minerals also undergo mineral transformations, such as dissolution of smectite and precipitation of illite, siderite and vivianite. These chemical, structural and mineralogical changes of clay minerals have a profound effect on clay mineral reactivity, such as their reactivity with organic and inorganic (i.e., heavy metals and radionuclides) contaminants. Our latest data show that biologically reduced nontronite (a smectite variety) is much more effective in reducing soluble and mobile Tc(VII) to Tc(IV) than unreduced nontronite. The reduced Tc(IV) is insoluble in groundwater and soil and thus is immobile. Biologically reduced nontronite can be prepared by microbially reducing Fe(III) in nontronite by Shewanella putrefaciens in the absence of oxygen. Approximately 30% of structurally Fe(III) can be reduced in this manner. Biogenic Fe(II) can then serve as an electron donor to reduce Tc(VII). Nearly all Fe(II) is available to reduce Tc(VII), with the rate of reduction (typically within weeks) possibly depending on the speciation of Fe(II) (surface sorbed Fe(II) vs. structural Fe(II)). Further investigations are underway to further assess the reversibility of Tc reduction upon exposure to oxygen and to elucidate Tc reduction

Rock-Fluid Interactions Under Stress: How Rock Microstructure Controls The Evolution of Porosity and Permeability

NASA Astrophysics Data System (ADS)

Vanorio, T.

2016-12-01

Monitoring chemo-mechanical processes geophysically — e.g., fluid disposal or storage, thermal and chemical stimulation of reservoirs, or natural fluids simply entering a new system in the subsurface— raises numerous concerns because of the likelihood of fluid-rock chemical interactions and our limited ability to decipher the geophysical signature of coupled processes. One of the missing links is coupling the evolution of porosity, permeability, and velocity of rocks together with reactive transport, since rocks deform and their microstructure evolves, as a result of chemical reactions under stress. This study describes recent advances in rock-physics experiments to understand the effects of dissolution-induced compaction on acoustic velocity, porosity, and permeability. Data observation includes time-lapse experiments and imaging tracking transport and elastic properties, the rock microstructure, and the pH and chemical composition of the fluid permeating the rock. Results show that the removal of high surface area, mineral phases such as microcrystalline calcite and clay appears to be mostly responsible for dissolution-induced compaction. Nevertheless, it is the original rock microstructure and its response to stress that ultimately defines how solution-transfer and rock compaction feed back upon each other. This work has a dual aim: understanding the mechanisms underlying permanent modifications to the rock microstructure and providing a richer set of experimental information to inform the formulation of new simulations and rock modeling.

Phosphine from rocks: mechanically driven phosphate reduction?

PubMed

Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

2005-11-01

Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks.

Metal transports and enrichments in iron depositions hosted in basaltic rocks. II: Metal rich fluids and Fe origin

NASA Astrophysics Data System (ADS)

Zhang, Ronghua; Zhang, Xuetong; Hu, Shumin

2015-12-01

This study focuses on revealing the mechanism of metal transport, enrichment and Fe origin of iron deposition during water basalt interactions occurred in basaltic rocks. Observations of the iron deposits (anhydrite-magnetite-pyroxene type deposits) hosted in K-rich basaltic rocks in the Mesozoic volcanic area of the Middle-Lower Yangtze River valley, China, indicate that the mechanism of metal transport and enrichment for those deposits are significant objective to scientists, and the Fe origin problem is not well resolved. Here the metal transport, enrichment and iron origin have been investigated in high temperature experiments of water basaltic interactions. These deposits were accompanying a wide zone with metal alteration. The effects of hydrothermal alteration on major rock-forming element concentrations in basaltic rock were investigated by systematically comparing the chemical compositions of altered rocks with those of fresh rocks. In the deposits, these metals are distributed throughout altered rocks that exhibit vertical zoning from the deeper to the shallow. Then, combined with the investigations of the metal-alterations, we performed kinetic experiments of water-basaltic rock interactions using flow-through reactors in open systems at temperatures from 20 °C to 550 °C, 23-34 MPa. Release rates for the rock-forming elements from the rocks have been measured. Experiments provide the release rates for various elements at a large temperature range, and indicate that the dissolution rates (release rates) for various elements vary with temperature. Si, Al, and K have high release rates at temperatures from 300 °C to 500 °C; the maximum release rates (RMX) for Si are reached at temperatures from 300 °C to 400 °C. The RMXs for Ca, Mg, and Fe are at low temperatures from 20 °C to 300 °C. Results demonstrate that Fe is not released from 400 °C to 550 °C, and indicate that when deep circling fluids passed through basaltic rocks, Fe was not mobile, and

Curiosity is Ready for Clay

NASA Image and Video Library

2018-03-22

This mosaic taken by NASA's Mars Curiosity rover looks uphill at Mount Sharp, which Curiosity has been climbing. Spanning the center of the image is an area with clay-bearing rocks that scientists are eager to explore; it could shed additional light on the role of water in creating Mount Sharp. The mosaic was assembled from dozens of images taken by Curiosity's Mast Camera (Mastcam). It was taken on Sol 1931 back in January. Mount Sharp stands in the middle of Gale Crater, which is 96 miles (154 kilometers) in diameter. This mound, which Curiosity has been climbing since 2014, likely formed in the presence of water at various points of time in Mars ancient history. That makes it an ideal place to study how water influenced the habitability of Mars billions of years ago. The scene has been white-balanced so the colors of the rock materials resemble how they would appear under daytime lighting conditions on Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22313

Comparative mineral chemistry and textures of SAFOD fault gouge and damage-zone rocks

USGS Publications Warehouse

Moore, Diane E.

2014-01-01

Creep in the San Andreas Fault Observatory at Depth (SAFOD) drillhole is localized to two foliated gouges, the central deforming zone (CDZ) and southwest deforming zone (SDZ). The gouges consist of porphyroclasts of serpentinite and sedimentary rock dispersed in a foliated matrix of Mg-smectite clays that formed as a result of shearing-enhanced reactions between the serpentinite and quartzofeldspathic rocks. The CDZ takes up most of the creep and exhibits differences in mineralogy and texture from the SDZ that are attributable to its higher shearing rate. In addition, a ∼0.2-m-wide sector of the CDZ at its northeastern margin (NE-CDZ) is identical to the SDZ and may represent a gradient in creep rate across the CDZ. The SDZ and NE-CDZ have lower clay contents and larger porphyroclasts than most of the CDZ, and they contain veinlets and strain fringes of calcite in the gouge matrix not seen elsewhere in the CDZ. Matrix clays in the SDZ and NE-CDZ are saponite and corrensite, whereas the rest of the CDZ lacks corrensite. Saponite is younger than corrensite, reflecting clay crystallization under declining temperatures, and clays in the more actively deforming portions of the CDZ have better equilibrated to the lower-temperature conditions.

Dehydroxylated clay silicates on Mars: Riddles about the Martian regolith solved with ferrian saponites

NASA Technical Reports Server (NTRS)

Burns, Roger G.

1992-01-01

Clay silicates, resulting from the chemical weathering of volcanic glasses and basaltic rocks of Mars, are generally believed to be major constituents of the martian regolith and atmospheric dust. Because little attention has been given to the role, if any, of Mg-bearing clay silicates on the martian surface, the crystal chemistry, stability, and reactivity of Mg-Fe smectites are examined. Partially dehydroxylated ferrian saponites are suggested to be major constituents of the surface of Mars, regulating several properties of the regolith.

Detecting a Difference in Clay Minerals at Two Gale Crater Sites

NASA Image and Video Library

2016-12-13

Data graphed here from the Chemistry and Camera (CheMin) instrument on NASA's Mars Curiosity rover show a difference between clay minerals in powder drilled from mudstone outcrops at two locations in Mars' Gale Crater: "Yellowknife Bay" and "Murray Buttes." CheMin's X-ray diffraction analysis reveals information about the crystalline structure of minerals in the rock. The intensity peaks marked with dotted vertical lines in this chart indicate that the crystalline structure of the two sites' clay minerals differs. The difference can be tied to a compositional difference in the clay minerals, as depicted in a diagram at PIA21148. The Yellowknife Bay site is on the floor of Gale Crater. The Murray Buttes site is on lower Mount Sharp, the layered mound in the center of the crater. http://photojournal.jpl.nasa.gov/catalog/PIA21147

Clays, specialty

USGS Publications Warehouse

Virta, R.L.

1998-01-01

Part of a special section on the state of industrial minerals in 1997. The state of the specialty clay industry worldwide for 1997 is discussed. The specialty clays mined in the U.S. are ball clay, fuller's earth, bentonite, fire clay, and kaolin. Sales of specialty clays in the U.S. were around 17 Mt in 1997. Approximately 53 kt of specialty clays were imported.

Sm-Nd dating of Fig Tree clay minerals of the Barberton greenstone belt, South Africa.

PubMed

Toulkeridis, T; Goldstein, S L; Clauer, N; Kroner, A; Lowe, D R

1994-03-01

Sm-Nd isotopic data from carbonate-derived clay minerals of the 3.22-3.25 Ga Fig Tree Group, Barberton greenstone belt, South Africa, form a linear array corresponding to an age of 3102 +/- 64 Ma, making these minerals the oldest dated clays on Earth. The obtained age is 120-160 m.y. younger than the depositional age determined by zircon geochronology. Nd model ages for the clays range from approximately 3.39 to 3.44 Ga and almost cover the age variation of the Barberton greenstone belt rocks, consistent with independent evidence that the clay minerals are derived from material of the belt. The combined isotopic and mineralogical data provide evidence for a cryptic thermal overprint in the sediments of the belt. However, the highest temperature reached by the samples since the time of clay-mineral formation was <300 degrees C, lower than virtually any known early Archean supracrustal sequence.

Sm-Nd dating of Fig Tree clay minerals of the Barberton greenstone belt, South Africa

NASA Technical Reports Server (NTRS)

Toulkeridis, T.; Goldstein, S. L.; Clauer, N.; Kroner, A.; Lowe, D. R.

1994-01-01

Sm-Nd isotopic data from carbonate-derived clay minerals of the 3.22-3.25 Ga Fig Tree Group, Barberton greenstone belt, South Africa, form a linear array corresponding to an age of 3102 +/- 64 Ma, making these minerals the oldest dated clays on Earth. The obtained age is 120-160 m.y. younger than the depositional age determined by zircon geochronology. Nd model ages for the clays range from approximately 3.39 to 3.44 Ga and almost cover the age variation of the Barberton greenstone belt rocks, consistent with independent evidence that the clay minerals are derived from material of the belt. The combined isotopic and mineralogical data provide evidence for a cryptic thermal overprint in the sediments of the belt. However, the highest temperature reached by the samples since the time of clay-mineral formation was <300 degrees C, lower than virtually any known early Archean supracrustal sequence.

In situ chemical osmosis experiment in the Boom Clay at the Mol underground research laboratory

NASA Astrophysics Data System (ADS)

Garavito, A. M.; De Cannière, P.; Kooi, H.

-permeability plastic formation such as the Boom Clay. The osmotic efficiency of Boom Clay is high under undisturbed chemical conditions ( σ = 0.41 at 0.014 M NaHCO 3), but rapidly decreases when the dissolved salts concentration increases ( σ = 0.07 at 0.14 M NaHCO 3). A semi-permeable membrane behaviour of the Boom Clay (high efficiencies) may be expected for the disposal of nitrate-bearing radioactive waste. However, the presently observed osmotically induced pressure is too low to have a significant mechanical impact on the host rock. Finally, the short duration of the osmosis test performed suggests that the shut-in test method used is effective for osmosis testing.

Surveying Clay Mineral Diversity in the Murray Formation, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Bristow, T. F.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Rampe, E. B.; Grotzinger, J. P.; McAdam, A. C.; Ming, D. W.; Morrison, S. M.; Yen, A. S.;

Environmental degradation of Opalinus Clay with cyclic variations in relative humidity

NASA Astrophysics Data System (ADS)

Wild, Katrin; Walter, Patric; Madonna, Claudio; Amann, Florian

2016-04-01

Clay shales are considered as favorable host rocks for nuclear waste repositories due to their low permeability, high sorption capacity and the potential for self-sealing. However, the favorable characteristics of the rock mass may change during tunnel excavation. Excavation is accompanied by stress redistribution and the development of an excavation damage zone. Furthermore, unloading and exposure to atmospheric conditions with a lower relative humidity (RH) causes desaturation of the rock mass close to the tunnel. This leads to shrinkage and the formation of desiccation cracks. During the open drift stage, seasonal atmospheric changes, especially RH variations, may alter the rock mass and influence the long-term crack evolution. This contribution discusses the influence of RH variation on the mechanical behavior of OPA. A series of specimens were exposed to short-term and long-term, stepwise cyclic RH variations between about 60 and 95% at constant temperature. Strains were measured using strain gauges to monitor the volumetric response during RH cycles. After each applied RH cycle, Brazilian tensile strength (BTS) tests were performed to identify whether there is a change in tensile strength due to environmental damage caused by the change in RH. Swelling and shrinkage of the specimens accompanied by irreversible volumetric expansion was observed as a consequence of the exposure to RH cycles. However, the irreversible strain was limited to the direction normal to bedding suggesting that internal damage is restricted along the bedding planes. No significant effect of cyclic RH variations on the BTS of the specimens was observed. The strength parallel to bedding remained constant over several cycles while the strength normal to bedding shows a slightly decreasing trend after 2 cycles. Furthermore, the water retention characteristics of the specimens were not altered significantly during stepwise RH cycling as the evolution of the water content was reversible

Ball clay

USGS Publications Warehouse

Virta, R.L.

2013-01-01

Four companies — H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co. and Unimin Corp. — mined ball clay in five U.S. states in 2012. Production, on the basis of preliminary data, was 900 kt (992,000 st), with an estimated value of $42.3 million. This was a slight increase in tonnage from 886 kt (977,000 st), with a value of $40.9 million in 2011. Tennessee was the leading ball clay producing state, with 63 percent of domestic production, followed by Texas, Mississippi, Kentucky and Indiana. Reported ball clay production from Indiana probably was fire clay rather than ball clay. About 69 percent of total ball clay production was airfloat, 20 percent was crude and 11 percent was water-slurried.

Killer clays! Natural antibacterial clay minerals

USGS Publications Warehouse

Williams, L.B.; Holland, M.; Eberl, D.D.; Brunet, T.; De Courrsou, L. B.

2004-01-01

The clay chemical properties that may be important in medicine were investigated. It was found that natural clay minerals can have striking and very specific effects on microbial populations. The effects can range from potentially enhanced microbial growth to complete sterilization. This paper presents evidence that natural clay minerals can be effective antimicrobial agents.

Surveying Clay Mineral Diversity in the Murray Formation, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Bristow, T.F.; Blake, D. F..; Vaniman, D. T.; Chipera, S. J.; Rampe, E. B.; Grotzinger, J. P.; McAdam, A. C.; Ming, D. W..; Morrison, S. M.; Yen, A. S.;

Ball clay

USGS Publications Warehouse

Virta, Robert L.

2010-01-01

The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

Mysterious Roving Rocks of Racetrack Playa

NASA Image and Video Library

2017-12-08

The rocks are famous because they move, leaving tell-tale trails in the clay, like this one. This happens at several playa in California and Nevada. There's no record of anybody seeing one of the rocks move, and scientists aren't quite sure how it happens. But they know that it's not the work of animals, gravity, or earthquakes. Photo credit: NASA/GSFC/Cynthia Cheung To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Acid rock drainage passive remediation using alkaline clay: Hydro-geochemical study and impacts of vegetation and sand on remediation.

PubMed

Plaza, Fernando; Wen, Yipei; Liang, Xu

2018-10-01

Acid rock drainage (ARD) is one of the most adverse environmental problems of the mine industry, especially in regions with an abundance of coal refuse (CR) deposits (e.g. the Northern Appalachian Coalfield in the USA) where surface and ground waters are affected by this pollution due to the acidity and high content of sulfates and heavy metals. This study explores the effectiveness of the ARD passive remediation method using alkaline clay (AC) through a series of static and long-term kinetic laboratory experiments (over three years) complemented with field measurements and geochemical modeling. Two important issues associated with this passive and auto-sustainable ARD remediation method were investigated: 1) the hydrogeochemical study of the mixture in terms of the percentages of AC and CR, and, 2) impacts of vegetation cover and a saturated sand barrier on the remediation. Both the field measurements and the samples used for the experiments came from a local coal waste site. Through the analysis of the field measurements and the outcome of the laboratory experiments and the geochemical modeling, alkaline clay proved to be an effective remediation material for ARD, in terms of achieving a neutral pH in the leachate and immobilization of sulfate and metals such as Fe, Mn, Cu, Zn, Ni, Pb, Cd, Co. Moreover, it has been demonstrated that the use of vegetation and a saturated sand barrier are beneficial. Vegetation acted as a phytoaccumulation/phytoextraction agent, causing an additional immobilization of metals. The saturated sand barrier blocked downward the oxygen and water diffusion, reducing pyrite oxidation rates. The proposed remediation approach ensures that the acidity consumption will likely occur before all the alkalinity is exhausted. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of Geologic Structures and Host Rock Properties Relevant to the Hydrogeology of the Standard Mine in Elk Basin, Gunnison County, Colorado

USGS Publications Warehouse

Caine, Jonathan S.; Manning, Andrew H.; Berger, Byron R.; Kremer, Yannick; Guzman, Mario A.; Eberl, Dennis D.; Schuller, Kathryn

2010-01-01

The Standard Mine Superfund Site is a source of mine drainage and associated heavy metal contamination of surface and groundwaters. The site contains Tertiary polymetallic quartz veins and fault zones that host precious and base metal sulfide mineralization common in Colorado. To assist the U.S. Environmental Protection Agency in its effort to remediate mine-related contamination, we characterized geologic structures, host rocks, and their potential hydraulic properties to better understand the sources of contaminants and the local hydrogeology. Real time kinematic and handheld global positioning systems were used to locate and map precisely the geometry of the surface traces of structures and mine-related features, such as portals. New reconnaissance geologic mapping, field and x-ray diffraction mineralogy, rock sample collection, thin-section analysis, and elemental geochemical analysis were completed to characterize hydrothermal alteration, mineralization, and subsequent leaching of metallic phases. Surface and subsurface observations, fault vein and fracture network characterization, borehole geophysical logging, and mercury injection capillary entry pressure data were used to document potential controls on the hydrologic system.

Organic and clay mineral diagenesis in Neogene sediments of western Taiwan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsueh, C.M.

1985-01-01

Three deep wells (two in the northern region and one in the southern region) with completion depths of over 5000m have been selected and the rock samples thoroughly examined. The TOC data of most samples studied are less than 1%, which is the TOC of an average shale. The low TOC is unfavorable for the Neogene sediments in western Taiwan as good source rocks. The data of C,H elemental analysis and Rock-Eval pyrolysis imply that the quality of kerogen in the northern region inclines to type II wet-gas prone, and in the southern region inclines to type III dry-gas prone.more » The maturity parameters of bitumen ratio, vitrinite reflectance, Tmax of Rock-Eval pyrolysis, and TTI of Lopatin's method show that the threshold of the oil-generative zone (about 0.6% Ro) in the northern region is in middle Miocene (about 3000m) and in the southern region is in lower Pliocene (about 4500m). The result of clay mineral analysis reveals that the transformation of smectitic clays to ordered mixed-layered smectite-illite can be identified and correlated with 0.6% Ro vitrinite reflectance. The illite crystallinity values are in the range of incipient to weak metamorphism and decrease with burial depth implying that the source area of low-grade metamorphic rocks has been uplifted rapidly so that the erosion from the exposed source area where the metamorphic grade became higher and higher was sufficiently fast to prevent weathering of illite. The Neogene sediments studied would not be expected to generate substantial amounts of oil. However, it can be expected that the pre-Miocene sediments in the northern region and the pre-Pliocene sediments in the southern region should have generated substantial amounts of gas at deeper depths.« less

Composition and properties of the Pierre Shale and equivalent rocks, northern Great Plains region

USGS Publications Warehouse

Schultz, Leonard Gene; Tourtelot, H.A.; Gill, J.R.; Boerngen, J.G.

1980-01-01

The Pierre Shale and equivalent rocks of Late Cretaceous age consist in the east-central Dakotas of several hundred feet of offshore-marine shale and minor marl; in west-central Montana near the sediment source the equivalents of the Pierre Shale consist of several thousand feet of volcanic-rich and mostly nonmarine sediments; and in the area between, both types of rock are separated by tongues of nearshore-marine siltstone and sandstone that mark three major transgressions of the sea across the area. The major-, minor-, and trace-element composition was determined for 226 samples of these rocks, and the mineralogical composition was determined for 1,350 samples. Slurry pH, Atterberg limits, and grain and bulk densities were determined on some samples. The arithmetic mean, in percent, and standard deviation (in parentheses) of major and minor elements, mostly in shale and siltstone and excluding the 23 chemically analyzed bentonite samples, are as follows: SiO2 60.8 (7.9) Al2O3 14.4 (2.5) Fe2O3 3.4 (1.4) FeO 1.1 (1.2) MgO 2.2 (1.0) CaO 2.7 (0.48) Na2O 1.1 (0.56) K2O 2.4 (0.57) H2O- 3.2 (1.3) H2O+ 4.3 (1.2) TiO2 0.58 (0.12) P2O5 0.14 (0.073) S 0.37 (1.1) F 0.71 (0.15) Cl 0.16 (0.024) CO2 2.1 (7.0) C, organic 0.94 (1.8) The mean and standard deviation of minerals as determined by X-ray methods, excluding bentonite samples, is as follows: clay minerals, 53 (20); quartz, 24 (13); cristobalite, 1 (5); potassium-feldspar, 1 (2); plagioclase, 6 (7); anorthite content from 20 to 40 percent; calcite, 5 (14); dolomite, 4 (7); organic matter, 1 (2); and sparsely scattered gypsum, jarosite, pyrite, zeolites, augite, siderite, and probably minor amounts of hydrated iron-manganese (Fe-Mn) oxides. The mean and standard deviation of the clay-mineral fraction is as follows: mixed-layer illite-smectite, 70 (20); illite, 16 (9); chlorite, 3 (6); and kaolinite, 9 (13). The mixed-layer clay, except in the Montana disturbed belt, is a random interlayering of 20 to 60 percent illite

Clay mineral formation under oxidized conditions and implications for paleoenvironments and organic preservation on Mars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gainey, Seth R.; Hausrath, Elisabeth M.; Adcock, Christopher T.

Clay mineral-bearing locations have been targeted for martian exploration as potentially habitable environments and as possible repositories for the preservation of organic matter. Although organic matter has been detected at Gale Crater, Mars, its concentrations are lower than expected from meteoritic and indigenous igneous and hydrothermal reduced carbon. We conducted synthesis experiments motivated by the hypothesis that some clay mineral formation may have occurred under oxidized conditions conducive to the destruction of organics. Previous work has suggested that anoxic and/or reducing conditions are needed to synthesize the Fe-rich clay mineral nontronite at low temperatures. In contrast, our experiments demonstrated themore » rapid formation of Fe-rich clay minerals of variable crystallinity from aqueous Fe3+ with small amounts of aqueous Mg2+. Our results suggest that Fe-rich clay minerals such as nontronite can form rapidly under oxidized conditions, which could help explain low concentrations of organics within some smectite-containing rocks or sediments on Mars.« less

Clay mineral formation under oxidized conditions and implications for paleoenvironments and organic preservation on Mars.

PubMed

Gainey, Seth R; Hausrath, Elisabeth M; Adcock, Christopher T; Tschauner, Oliver; Hurowitz, Joel A; Ehlmann, Bethany L; Xiao, Yuming; Bartlett, Courtney L

2017-11-01

Clay mineral-bearing locations have been targeted for martian exploration as potentially habitable environments and as possible repositories for the preservation of organic matter. Although organic matter has been detected at Gale Crater, Mars, its concentrations are lower than expected from meteoritic and indigenous igneous and hydrothermal reduced carbon. We conducted synthesis experiments motivated by the hypothesis that some clay mineral formation may have occurred under oxidized conditions conducive to the destruction of organics. Previous work has suggested that anoxic and/or reducing conditions are needed to synthesize the Fe-rich clay mineral nontronite at low temperatures. In contrast, our experiments demonstrated the rapid formation of Fe-rich clay minerals of variable crystallinity from aqueous Fe 3+ with small amounts of aqueous Mg 2+ . Our results suggest that Fe-rich clay minerals such as nontronite can form rapidly under oxidized conditions, which could help explain low concentrations of organics within some smectite-containing rocks or sediments on Mars.

Mysterious Roving Rocks of Racetrack Playa

NASA Image and Video Library

2017-12-08

Four LPSA interns test the clay at Bonnie Claire Playa, another location where the rocks move, to see how quickly water is absorbed. Interns, clockwise: Kyle Yawn (standing), Gregory Romine, Emily Kopp, and Clint Naquin. Photo credit: NASA/GSFC/Maggie McAdam To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Constraints on the Nature and Distribution of Iridium Host Phases at the Cretaceous-Tertiary Boundary: Implications for Projectile Identity and dispersal on impact

NASA Technical Reports Server (NTRS)

Schuraytz, B. C.; Lindstrom, D. J.; Sharpton, V. L.

1997-01-01

microscopy in melt-rock samples from two widely separated drill holes at the Chicxulub Basin, including a replicate split of Y6-NI9-R. One is an aggregate of subhedral Ir metal grains enclosed in silicate, in which no other Pt group elements (PGE) were detected. A second particle with twice the mass as the first, concentrated predominantly in a single grain, is associated with minor concentrations of Os, Ru, and Pt, and with adhering particles of corundum and perovskite. A third Ir-rich particle, with a greater apparent Os concentration, was identified before being lost as a result of charging under the electron beam. In addition to demonstrating the preservation of projectile components within the Chicxulub Crater, analogous phase associations in Ca- and Al-rich inclusions (CAI) from C2 and C3 chondrites suggest to us that these melt-rock Ir host phases are relics from a carbonaceous chondrite K/T boundary impactor Although the obviously low Ru/Ir ratios of the Chicxulub Ir host phases are qualitatively consistent with suggested PGE fractionation with distance during condensation in an ejecta cloud, it seems difficult to explain the accumulation of the about 3 x 10(exp 11) Ir atoms required to form a about 10(exp -10) g nugget of pure Ir metal within a jet of vaporized projectile expanding at 1-4 km/s, or to effectively exclude or remove commonly alloyed PGE and siderophile elements by fractionation processes resulting from condensation, oxidation, sulfidization, exsolution, or autometamorphism during cooling of the melt. We do not dismiss the importance of these processes entirely; on the contrary, other geochemical and mineralogical aspects of the melt rocks require them, and condensation from the expanding ejecta cloud appears to best explain the primary Ir host-phase distribution in the fish clay, as well as the high Ir concentrations associated with spinel-bearing spheroids at the K/T boundary in the Pacific Ocean . If the "relict" hypothesis is correct, micronuggets

Ball clay

USGS Publications Warehouse

Virta, R.L.

2011-01-01

The article discusses the latest developments in the global ball clay mining industry, particularly in the U.S., as of June 2011. It cites several firms that are involved in ball clay mining in the U.S., including HC Spins Clay Co. Inc., the Imerys Group and Old Hickory Clay Co. Among the products made from ball clay are ceramic tiles, sanitaryware, as well as fillers, extenders and binders.

Professor M. M. Protod’yakonov’s Strength Coefficient f of Rocks,

DTIC Science & Technology

1981-11-12

of rock strengths. Prof. A. F. Sukhanov citpd such arguments as the fact that clay is easy to drill but difficult to blast hbile granite is equally...two rocks. on the basis of theste exauFles A. F. Sukhanov concluded that the coefficients of drillability and blastability are not equal and are nct...his work (6] A. F. Sukhanov gives a consoliditcea table (32) of varicus indicas of mechanical properties of rocks. The coefficient of relative strength

Experimental alteration of artificial and natural impact melt rock from the Chesapeake Bay impact structure

USGS Publications Warehouse

Declercq, J.; Dypvik, H.; Aagaard, Per; Jahren, J.; Ferrell, R.E.; Horton, J. Wright

2009-01-01

The alteration or transformation of impact melt rock to clay minerals, particularly smectite, has been recognized in several impact structures (e.g., Ries, Chicxulub, Mj??lnir). We studied the experimental alteration of two natural impact melt rocks from suevite clasts that were recovered from drill cores into the Chesapeake Bay impact structure and two synthetic glasses. These experiments were conducted at hydrothermal temperature (265 ??C) in order to reproduce conditions found in meltbearing deposits in the first thousand years after deposition. The experimental results were compared to geochemical modeling (PHREEQC) of the same alteration and to original mineral assemblages in the natural melt rock samples. In the alteration experiments, clay minerals formed on the surfaces of the melt particles and as fine-grained suspended material. Authigenic expanding clay minerals (saponite and Ca-smectite) and vermiculite/chlorite (clinochlore) were identified in addition to analcime. Ferripyrophyllite was formed in three of four experiments. Comparable minerals were predicted in the PHREEQC modeling. A comparison between the phases formed in our experiments and those in the cores suggests that the natural alteration occurred under hydrothermal conditions similar to those reproduced in the experiment. ?? 2009 The Geological Society of America.

Generic Argillite/Shale Disposal Reference Case

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Liange; Colon, Carlos Jové; Bianchi, Marco

Radioactive waste disposal in a deep subsurface repository hosted in clay/shale/argillite is a subject of widespread interest given the desirable isolation properties, geochemically reduced conditions, and widespread geologic occurrence of this rock type (Hansen 2010; Bianchi et al. 2013). Bianchi et al. (2013) provides a description of diffusion in a clay-hosted repository based on single-phase flow and full saturation using parametric data from documented studies in Europe (e.g., ANDRA 2005). The predominance of diffusive transport and sorption phenomena in this clay media are key attributes to impede radionuclide mobility making clay rock formations target sites for disposal of high-level radioactivemore » waste. The reports by Hansen et al. (2010) and those from numerous studies in clay-hosted underground research laboratories (URLs) in Belgium, France and Switzerland outline the extensive scientific knowledge obtained to assess long-term clay/shale/argillite repository isolation performance of nuclear waste. In the past several years under the UFDC, various kinds of models have been developed for argillite repository to demonstrate the model capability, understand the spatial and temporal alteration of the repository, and evaluate different scenarios. These models include the coupled Thermal-Hydrological-Mechanical (THM) and Thermal-Hydrological-Mechanical-Chemical (THMC) models (e.g. Liu et al. 2013; Rutqvist et al. 2014a, Zheng et al. 2014a) that focus on THMC processes in the Engineered Barrier System (EBS) bentonite and argillite host hock, the large scale hydrogeologic model (Bianchi et al. 2014) that investigates the hydraulic connection between an emplacement drift and surrounding hydrogeological units, and Disposal Systems Evaluation Framework (DSEF) models (Greenberg et al. 2013) that evaluate thermal evolution in the host rock approximated as a thermal conduction process to facilitate the analysis of design options. However, the assumptions and the

Curiosity is Ready for Clay (Highlighted)

NASA Image and Video Library

2018-03-22

This mosaic taken by NASA's Mars Curiosity rover looks uphill at Mount Sharp, which Curiosity has been climbing. Highlighted in white is an area with clay-bearing rocks that scientists are eager to explore; it could shed additional light on the role of water in creating Mount Sharp. The mosaic was assembled from dozens of images taken by Curiosity's Mast Camera (Mastcam). It was taken on Sol 1931 back in January. Mount Sharp stands in the middle of Gale Crater, which is 96 miles (154 kilometers) in diameter. This mound, which Curiosity has been climbing since 2014, likely formed in the presence of water at various points of time in Mars ancient history. That makes it an ideal place to study how water influenced the habitability of Mars billions of years ago. The scene has been white-balanced so the colors of the rock materials resemble how they would appear under daytime lighting conditions on Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22312

Proceedings of the scientific visit on crystalline rock repository development.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mariner, Paul E.; Hardin, Ernest L.; Miksova, Jitka

2013-02-01

A scientific visit on Crystalline Rock Repository Development was held in the Czech Republic on September 24-27, 2012. The visit was hosted by the Czech Radioactive Waste Repository Authority (RAWRA), co-hosted by Sandia National Laboratories (SNL), and supported by the International Atomic Energy Agency (IAEA). The purpose of the visit was to promote technical information exchange between participants from countries engaged in the investigation and exploration of crystalline rock for the eventual construction of nuclear waste repositories. The visit was designed especially for participants of countries that have recently commenced (or recommenced) national repository programmes in crystalline host rock formations.more » Discussion topics included repository programme development, site screening and selection, site characterization, disposal concepts in crystalline host rock, regulatory frameworks, and safety assessment methodology. Interest was surveyed in establishing a %E2%80%9Cclub,%E2%80%9D the mission of which would be to identify and address the various technical challenges that confront the disposal of radioactive waste in crystalline rock environments. The idea of a second scientific visit to be held one year later in another host country received popular support. The visit concluded with a trip to the countryside south of Prague where participants were treated to a tour of the laboratory and underground facilities of the Josef Regional Underground Research Centre.« less

Chemically-bonded brick production based on burned clay by means of semidry pressing

NASA Astrophysics Data System (ADS)

Voroshilov, Ivan; Endzhievskaya, Irina; Vasilovskaya, Nina

2016-01-01

We presented a study on the possibility of using the burnt rocks of the Krasnoyarsk Territory for production of chemically-bonded materials in the form of bricks which are so widely used in multistory housing and private house construction. The radiographic analysis of the composition of burnt rock was conducted and a modifier to adjust the composition uniformity was identified. The mixing moisture content was identified and optimal amount at 13-15% was determined. The method of semidry pressing has been chosen. The process of obtaining moldings has been theoretically proved; the advantages of chemically-bonded wall materials compared to ceramic brick were shown. The production of efficient artificial stone based on material burnt rocks, which is comparable with conventionally effective ceramic materials or effective with cell tile was proved, the density of the burned clay-based cell tile makes up to 1630-1785 kg m3, with compressive strength of 13.6-20.0 MPa depending on the compression ratio and cement consumption, frost resistance index is F50, and the thermal conductivity in the masonry is λ = 0,459-0,546 W m * °C. The clear geometric dimensions of pressed products allow the use of the chemically-bonded brick based on burnt clay as a facing brick.

Ball clay

USGS Publications Warehouse

Virta, R.L.

2007-01-01

The article offers information on ball clay. Among the companies that mine ball clay in the U.S. are H.C. Spinks Clay, Kentucky-Tennessee Clay and Old Hickory Clay. In 2006, an estimated 1.2 million tons of the mineral was sold or used domestically and exported. Forty-percent of the total sales is accounted for ceramic floor and wall tile followed by sanitaryware and miscellaneous ceramics. Its average value was $ 45 per ton in 2006.

Influence of Clay Content, Mineralogy and Fabric On Radar Frequency Response of Aquifer Materials

NASA Astrophysics Data System (ADS)

West, L. J.; Handley, K.

High frequency electromagnetic methods such as ground penetrating radar (GPR) and time domain reflectometry (TDR) are widely employed to measure water saturation in the vadose zone and water filled porosity in the saturated zone. However, previous work has shown that radar frequency dielectric properties are strongly influenced by clay as well as by water content. They have also shown that that the dielectric response of clay minerals is strongly frequency dependent, and that even a small proportion of clay such as that present in many sandstone aquifers can have a large effect at typi- cal GPR frequencies (around 100MHz). Hence accurate water content/porosity deter- mination requires clay type and content to be taken into account. Reported here are dielectric measurements on clay-sand mixtures, aimed at investigating the influence of clay mineralogy, particle shape, and the geometrical arrangement of the mixture constituents on GPR and TDR response. Dielectric permittivity (at 50-1000MHz) was measured for mixtures of Ottawa Sand and various clay minerals or clay size quartz rock flour, using a specially constructed dielectric cell. Both homogeneous and layered mixtures were tested. The influence of pore water salinity, clay type, and particle arrangement on the dielectric response is interpreted in terms of dielectric dispersion mechanisms. The appropriateness of var- ious dielectric mixing rules such as the Complex Refractive Index Method (CRIM) for determination of water content or porosity from field GPR and TDR data are dis- cussed.

Clay Mineralogy, Authigenic Smectite Concentration, and Fault Weakening of the San Gregorio Fault; Moss Beach, California

NASA Astrophysics Data System (ADS)

Mazzoni, S.; Moore, J.; Bish, D. L.

2002-12-01

The apparently weak nature of the San Andreas fault system poses a fundamental geophysical question. The San Gregorio fault at Moss Beach, CA is an active splay of the right-lateral San Andreas fault zone and has a total offset of about 150 km. At Moss Beach, the San Gregorio fault offsets Pliocene sedimentary rocks and consists of a clay-rich gouge zone, eastern sandstone block, and western mudstone block. In the presence of fluids, smectite clays can swell and become very weak to shearing. We studied a profile of samples across the fault zone and wall rocks to determine if there is a concentration of smectite in the gouge zone and propose a possible formation mechanism. Samples were analyzed using standard quantitative X-ray diffraction methods and software recently developed at Los Alamos National Lab. XRD results show a high smectite/illite (weak clay/strong clay) ratio in the gouge (S/I ratio=2-4), lower in the mudstone (S/I ratio=2), and very low in the sandstone (S/I ratio=1). The variability of smectite/illite ratio in the gouge zone may be evidence of preferential alteration where developed shear planes undergo progressive smectite enrichment. The amount of illite layers in illite/smectites is 5-30%, indicating little illitization; therefore, these fault rocks have not undergone significant diagenesis above 100 degrees C and illite present must be largely detrital. Bulk mineralogy shows significant anti-correlation of smectite with feldspar, especially in the gouge, suggesting authigenic smectite generation from feldspar. Under scanning-electron microscope inspection, smectites have fibrous, grain coating growth fabrics, also suggesting smectite authigenesis. If in situ production of smectite via chemical alteration is possible in active faults, it could have significant implications for self-generated weakening of faults above the smectite-to-illite transition (<150 degrees C, or 5-7km).

Age and geochemistry of host rocks of the Cobre Panama porphyry Cu-Au deposit, central Panama: Implications for the Paleogene evolution of the Panamanian magmatic arc

NASA Astrophysics Data System (ADS)

Baker, Michael J.; Hollings, Peter; Thompson, Jennifer A.; Thompson, Jay M.; Burge, Colin

2016-04-01

The Cobre Panama porphyry Cu-Au deposit, located in the Petaquilla district of central Panama, is hosted by a sequence of medium- to high-K calc-alkaline volcanic and sub-volcanic rocks. New crystallisation ages obtained from a granodiorite Petaquilla batholith and associated mineralised diorite to granodiorite porphyry stocks and dikes at Cobre Panama indicate that the batholith was emplaced as a multi-phase intrusion, over a period of 4 million years from 32.20 ± 0.76 Ma to 28.26 ± 0.61 Ma, while the porphyritic rocks were emplaced over a 2 million year period from 28.96 ± 0.62 Ma to 27.48 ± 0.68 Ma. Both the volcanic to sub-volcanic host rocks and intrusive rocks of the Cobre Panama deposit evolved via fractional crystallisation processes, as demonstrated by the major elements (e.g. Al2O3, Fe2O3, TiO2 and MgO) displaying negative trends with increasing SiO2. The Petaquilla intrusive rocks, including the diorite-granodiorite porphyries and granodiorite batholith, are geochemically evolved and appear to have formed from more hydrous magmas than the preceding host volcanic rocks, as evidenced by the presence of hornblende phenocrysts, higher degrees of large-ion lithophile element (LILE) and light rare earth element (LREE) enrichment and heavy rare earth element (HREE) depletion, and higher Sr/Y and La/Yb values. However, the degree of LREE enrichment, HREE depletion and La/Yb values are insufficient for the intrusive rocks to be considered as adakites. Collectively, the volcanic and intrusive rocks have LILE, REE and mobile trace element concentrations similar to enriched Miocene-age Cordilleran arc magmatism found throughout central and western Panama. Both the Petaquilla and Cordilleran arc magmatic suites are geochemically more evolved than the late Cretaceous to Eocene Chagres-Bayano arc magmas from northeastern Panama, as they display higher degrees of LILE and LREE enrichment. The geochemical similarities between the Petaquilla and Cordilleran arc magmas

Used Fuel Disposal in Crystalline Rocks. FY15 Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yifeng

2015-08-20

The objective of the Crystalline Disposal R&D Work Package is to advance our understanding of long-term disposal of used fuel in crystalline rocks and to develop necessary experimental and computational capabilities to evaluate various disposal concepts in such media. Chapter headings are as follows: Fuel matrix degradation model and its integration with performance assessments, Investigation of thermal effects on the chemical behavior of clays, Investigation of uranium diffusion and retardation in bentonite, Long-term diffusion of U(VI) in bentonite: dependence on density, Sorption and desorption of plutonium by bentonite, Dissolution of plutonium intrinsic colloids in the presence of clay and asmore » a function of temperature, Laboratory investigation of colloid-facilitated transport of cesium by bentonite colloids in a crystalline rock system, Development and demonstration of discrete fracture network model, Fracture continuum model and its comparison with discrete fracture network model.« less

Central Antarctic provenance of Permian sandstones in Dronning Maud Land and the Karoo Basin: Integration of U Pb and TDM ages and host-rock affinity from detrital zircons

NASA Astrophysics Data System (ADS)

Veevers, J. J.; Saeed, A.

2007-12-01

In conjugate SE Africa and Antarctica, Early Permian sandstones of the Swartrant Formation of the Ellisras Basin, Vryheid Formation of the Karoo Basin, and Amelang Plateau Formation of Dronning Maud Land (DML) were deposited after Gondwanan glaciation on a westward paleoslope. We analysed detrital zircons for U-Pb ages by a laser ablation microprobe-inductively coupled plasma mass spectrometer (LAM-ICPMS) and attached age significance only to clusters of three or more overlapping analyses. We analysed Hf-isotope compositions by a multi-collector spectrometer (LAM-MC-ICPMS) and trace elements by electron microprobe (EMP) and ICPMS. These analyses indicate the rock type and source (whether crustal or juvenile mantle) of the host magma, and a "crustal" model age ( TDMC). The integrated analysis gives a more distinctive, and more easily interpreted, picture of crustal evolution in the provenance area than age data alone. Zircons from the Ellisras Basin are aged 2700-2540 Ma with minor populations about 2815 Ma and 2040 Ma, which correspond with the ages of the upslope parts of the proximal Kaapvaal Craton and Limpopo Belt. Mafic rock is the dominant host rock, and it reflects the Archean granite-greenstone terrane of the Kaapvaal Craton. The three Karoo Basin samples and the two DML samples have zircons with these common properties: (1) 1160-880 Ma, host magma mafic granitoid (< 65% SiO 2) derived from juvenile depleted mantle sources ( ɛHf positive) at 1.65 Ga and 1.35 Ga, with TDMC of 2.0-0.9 Ga; (2) 760 to 480 Ma, host magma granitoid and low-heavy rare earth element rock (?alkaline rock-carbonatite), derived from mixed crustal and juvenile depleted mantle sources ( ɛHf positive and negative) at 1.50 Ga and 1.35 Ga, with TDMC of 2.0-0.9 Ga. Together with similar detrital zircons in Triassic sandstone of SE Australia, these properties reflect those in upslope central Antarctica, indicating a provenance of ˜ 1000 Ma (Grenville) cratons embedded in 700-500 Ma (Pan

In search of early life: Carbonate veins in Archean metamorphic rocks as potential hosts of biomarkers

NASA Astrophysics Data System (ADS)

Peters, Carl A.; Piazolo, Sandra; Webb, Gregory E.; Dutkiewicz, Adriana; George, Simon C.

2016-11-01

The detection of early life signatures using hydrocarbon biomarkers in Precambrian rocks struggles with contamination issues, unspecific biomarkers and the lack of suitable sedimentary rocks due to extensive thermal overprints. Importantly, host rocks must not have been exposed to temperatures above 250 °C as at these temperatures biomarkers are destroyed. Here we show that Archean sedimentary rocks from the Jeerinah Formation (2.63 billion yrs) and Carawine Dolomite (2.55 billion yrs) of the Pilbara Craton (Western Australia) drilled by the Agouron Institute in 2012, which previously were suggested to be suitable for biomarker studies, were metamorphosed to the greenschist facies. This is higher than previously reported. Both the mineral assemblages (carbonate, quartz, Fe-chlorite, muscovite, microcline, rutile, and pyrite with absence of illite) and chlorite geothermometry suggest that the rocks were exposed to temperatures higher than 300 °C and probably ∼400 °C, consistent with greenschist-facies metamorphism. This facies leads to the destruction of any biomarkers and explains why the extraction of hydrocarbon biomarkers from pristine drill cores has not been successful. However, we show that the rocks are cut by younger formation-specific carbonate veins containing primary oil-bearing fluid inclusions and solid bitumens. Type 1 veins in the Carawine Dolomite consist of dolomite, quartz and solid bitumen, whereas type 2 veins in the Jeerinah Formation consist of calcite. Within the veins fluid inclusion homogenisation temperatures and calcite twinning geothermometry indicate maximum temperatures of ∼200 °C for type 1 veins and ∼180 °C for type 2 veins. Type 1 veins have typical isotopic values for reprecipitated Archean sea-water carbonates, with δ13CVPDB ranging from - 3 ‰ to 0‰ and δ18OVPDB ranging from - 13 ‰ to - 7 ‰, while type 2 veins have isotopic values that are similar to hydrothermal carbonates, with δ13CVPDB ranging from - 18 �

Clay mineral distribution along the southern and western Svalbard continental margin in association with contouritic deposition: insights for environmental and oceanographic reconstruction

NASA Astrophysics Data System (ADS)

Musco, Maria Elena; Caricchi, Chiara; Giulia Lucchi, Renata; Princivalle, Francesco; GIorgetti, Giovanna; Caburlotto, Andrea

2017-04-01

The Kveithola and Storfjorden troughs are two glacial depositional systems, situated South of the Svalbard Archipelago (North Western Barents Sea), that during the last glaciation (MIS-2) have hosted ice streams, which contributed to the build-up of the relative Trough Mouth Fans (TMFs) on the continental slope. The sedimentary record contained in TMFs provides several proxies that can be useful for reconstructing the ice-streams dynamics during glacial periods, the onset of deglaciation and the climatic variability during interglacials. The TMF slopes facing the two troughs have been investigated during several international oceanographic cruises: SVAIS onboard R/V BIO Hespérides; EGLACOM, onboard R/V OGS Explora; PNRA Project CORIBAR, onboard R/V Maria S. Marien; Eurofleets-2 PREPARED, onboard RV-G.O. Sars. For this study we have focused on XRD analyses on clay minerals, collected from seven cores, taken during these cruises, and XRF analyses have also been conducted on the whole length of the cores. Clay mineral assemblages are controlled by source rock composition, physical-chemical weathering, transport and depositional mechanisms. In polar areas clay mineral analysis can be used also for reconstructing sedimentary processes, associated with glacial and interglacial conditions. Moreover in the North western Barents Sea smectite is considered a good proxy for reconstructing the North Atlantic Current strength, giving thus additional indication on the palaeoceanographic conditions associated with climatic changes. Here we present a first correlation among these cores, aiming to describe the clay mineral distribution in response to the climatic variations that followed the Last Glacial Maximum and describe the changes in ice-stream dynamics and related oceanographic/environmental changes along the margin.

Clay Play

ERIC Educational Resources Information Center

Rogers, Liz; Steffan, Dana

2009-01-01

This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

Fire clay

USGS Publications Warehouse

Virta, R.L.

2013-01-01

Four companies mined fire clay in three states in 2012. Production, based on a preliminary survey of the fire clay industry, was estimated to be 230 kt (254,000 st) valued at $6.98 million, an increase from 215 kt (237,000 st) valued at $6.15 million in 2011. Missouri was the leading producing state, followed by Colorado and Texas, in decreasing order by quantity. The number of companies mining fire clay declined in 2012 because several common clay producers that occasionally mine fire clay indicated that they did not do so in 2012.

Ball clay

USGS Publications Warehouse

Virta, R.L.

2001-01-01

Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

Complicated secondary textures in zircon record evolution of the host granitic rocks: Studies from Western Tauern Window and Ötztal-Stubai Crystalline Complex (Eastern Alps, Western Austria)

NASA Astrophysics Data System (ADS)

Kovaleva, Elizaveta; Harlov, Daniel; Klötzli, Urs

2017-07-01

Samples of metamorphosed and deformed granitic rocks were collected from two Alpine complexes with well-constrained metamorphic history: Western Tauern Window and Ötztal-Stubai Crystalline Complex. Zircon grains from these samples were investigated in situ by a combination of scanning electron microscope techniques, cathodoluminescence (CL) imaging and Raman spectroscopy. The aims were: to describe and interpret complicated secondary textures and microstructures in zircon; based on cross-cutting relationships between secondary microstructures, reconstruct the sequence of processes, affecting zircon crystals; link the evolution of zircon with the history of the host rocks. The results indicate that zircon in the sampled granitic rocks forms growth twins and multi-grain aggregates, which are unusual for this mineral. Moreover, various secondary textures have been found in the sampled zircon, often cross-cutting each other in a single crystal. These include: distorted oscillatory CL zoning with inner zones forming inward-penetrating, CL-bright embayments, which are the evidence of dry recrystallization via annealing/lattice recovery; CL mosaicism with no preservation of growth zoning, but abundant nano- and micro-scale pores and mineral inclusions, which are the evidence of recrystallization by coupled dissolution-reprecipitation and/or leaching; embayed zircon boundaries filled with apatite, monazite, epidote and mylonitic matrix, indicating mineral-fluid reactions resulting in zircon dissolution and fragmentation; overgrowth CL-dark rims, which contain nano-pores and point to transport and precipitation of dissolved zircon matter. We conclude that zircon in our meta-granites is sensitive to metamorphism/deformation events, and was reactive with metamorphic fluids. Additionally, we have found evidence of crystal-plastic deformation in the form of low angle boundaries and bent grain tips, which is a result of shearing and ductile deformation of the host rock. We

The ultimate mineral processing challenge: Recovery of rare earths, phosphorus and uranium from Florida phosphatic clay

DOE PAGES

Zhang, Patrick; Liang, Haijun; Jin, Zhen; ...

2017-11-01

We report phosphate beneficiation in Florida generates more than one tonne of phosphatic clay, or slime, per tonne of phosphate rock produced. Since the start of the practice of large-scale washing and desliming for phosphate beneficiation, more than 2 Gt of slime has accumulated, containing approximately 600 Mt of phosphate rock, 600 kt of rare earth elements (REEs) and 80 million kilograms of uranium. The recovery of these valuable elements from the phosphatic clay is one of the most challenging endeavors in mineral processing, because the clay is extremely dilute, with an average solids concentration of 3 percent, and finemore » in size, with more than 50 percent having particle size smaller than 2 μm, and it contains nearly 50 percent clay minerals as well as large amounts of magnesium, iron and aluminum. With industry support and under funding from the Critical Materials Institute, the Florida Industrial and Phosphate Research Institute in conjunction with the Oak Ridge National Laboratory undertook the task to recover phosphorus, rare earths and uranium from Florida phosphatic clay. This paper presents the results from the preliminary testing of two approaches. The first approach involves three-stage cycloning using cyclones with diameters of 12.4 cm (5 in.), 5.08 cm (2 in.) and 2.54 cm (1 in.), respectively, to remove clay minerals followed by flotation and leaching. The second approach is a two-step leaching process. In the first step, selective leaching was conducted to remove magnesium, thus allowing the production of phosphoric acid suitable for the manufacture of diammonium phosphate (DAP) in the second leaching step. The results showed that multistage cycloning with small cyclones is necessary to remove clay minerals. Finally, selective leaching at about pH 3.2 using sulfuric acid was found to be effective for removing more than 80 percent of magnesium from the feed with minimal loss of phosphorus.« less

The ultimate mineral processing challenge: Recovery of rare earths, phosphorus and uranium from Florida phosphatic clay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Patrick; Liang, Haijun; Jin, Zhen

We report phosphate beneficiation in Florida generates more than one tonne of phosphatic clay, or slime, per tonne of phosphate rock produced. Since the start of the practice of large-scale washing and desliming for phosphate beneficiation, more than 2 Gt of slime has accumulated, containing approximately 600 Mt of phosphate rock, 600 kt of rare earth elements (REEs) and 80 million kilograms of uranium. The recovery of these valuable elements from the phosphatic clay is one of the most challenging endeavors in mineral processing, because the clay is extremely dilute, with an average solids concentration of 3 percent, and finemore » in size, with more than 50 percent having particle size smaller than 2 μm, and it contains nearly 50 percent clay minerals as well as large amounts of magnesium, iron and aluminum. With industry support and under funding from the Critical Materials Institute, the Florida Industrial and Phosphate Research Institute in conjunction with the Oak Ridge National Laboratory undertook the task to recover phosphorus, rare earths and uranium from Florida phosphatic clay. This paper presents the results from the preliminary testing of two approaches. The first approach involves three-stage cycloning using cyclones with diameters of 12.4 cm (5 in.), 5.08 cm (2 in.) and 2.54 cm (1 in.), respectively, to remove clay minerals followed by flotation and leaching. The second approach is a two-step leaching process. In the first step, selective leaching was conducted to remove magnesium, thus allowing the production of phosphoric acid suitable for the manufacture of diammonium phosphate (DAP) in the second leaching step. The results showed that multistage cycloning with small cyclones is necessary to remove clay minerals. Finally, selective leaching at about pH 3.2 using sulfuric acid was found to be effective for removing more than 80 percent of magnesium from the feed with minimal loss of phosphorus.« less

10 CFR 960.4-2-3 - Rock characteristics.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Rock characteristics. 960.4-2-3 Section 960.4-2-3 Energy... REPOSITORY Postclosure Guidelines § 960.4-2-3 Rock characteristics. (a) Qualifying condition. The present and expected characteristics of the host rock and surrounding units shall be capable of accommodating the...

Studies of electrical properties of low-resistivity sandstones based on digital rock technology

NASA Astrophysics Data System (ADS)

Yan, Weichao; Sun, Jianmeng; Zhang, Jinyan; Yuan, Weiguo; Zhang, Li; Cui, Likai; Dong, Huaimin

2018-02-01

Electrical properties are important parameters to quantitatively calculate water saturation in oil and gas reservoirs by well logging interpretation. It is usual that oil layers show high resistivity responses, while water layers show low-resistivity responses. However, there are low-resistivity oil zones that exist in many oilfields around the world, leading to difficulties for reservoir evaluation. In our research, we used digital rock technology to study different internal and external factors to account for low rock resistivity responses in oil layers. We first constructed three-dimensional digital rock models with five components based on micro-computed tomography technology and x-ray diffraction experimental results, and then oil and water distributions in pores were determined by the pore morphology method. When the resistivity of each component was assigned, rock resistivities were calculated by using the finite element method. We collected 20 sandstone samples to prove the effectiveness of our numerical simulation methods. Based on the control variate method, we studied the effects of different factors on the resistivity indexes and rock resistivities. After sensitivity analyses, we found the main factors which caused low rock resistivities in oil layers. For unfractured rocks, influential factors arranged in descending order of importance were porosity, clay content, temperature, water salinity, heavy mineral, clay type and wettability. In addition, we found that the resistivity index could not provide enough information to identify a low-resistivity oil zone by using laboratory rock-electric experimental results. These results can not only expand our understandings of the electrical properties of low-resistivity rocks from oil layers, but also help identify low-resistivity oil zones better.

Very low-grade metamorphic rocks in some representative districts in Tibet

NASA Astrophysics Data System (ADS)

Bi, X.; Mo, X.

2011-12-01

*Response author: Bi,Xianmei,bixm10@sina.com Very low grade metamorphic rocks are widely distributed in Tibet, providing an insight into deformation and metamorphism during the evolution of the Tibetan Plateau. Eighty five Samples of clay mineral-bearing rocks has been collected from various strata including D, P1, T1, T2, T3, J1, J3, K1, K2 and N strata in the Qiangtang terrane, the Gangdese, the Yarlung Zangbo suture and the Tethyan Himalaya. Analyses and refining of clay minerals in samples have been conducted in the Laboratory of X-ray Diffraction, Institute of Petroleum Exploration. Index of illite crystallinity (Ic) along with average thickness of crystal layers of illite, reflectivity of vitrinite and of clay mineral association have been employed as indicators of degree of very low-grade metamorphism. The scheme of classification[1,2] of very-low grade metamorphism based on clay mineral indexes ( mainly index of illite crystallinity) has been used in the present work, that is, low metamorphism (Ic<0.25), higher very-low grade metamorphism (Ic = 0.25-0.30), lower very-low grade metamorphism (Ic = 0.30-0.42) and diagenesis (Ic>0.42). The analytical results show interesting information. In the Qiangtang terrane, clay minerals in the Jurassic strata have indexes of illite crystalinity (Ic) 0.47-0.70, indicating higher diagenesis and in favor of petroleum-generation. However, index of illite crystalinity (Ic) for the Devonian is 0.23, indicating low metamorphism. Indexes of illite crystalinity (Ic) for the J-K strata in middle Gangdese are mostly 0.37-0.25 (very-low grade metamorphism) and a few 0.78-0.48 (diagenesis). Indexes of illite crystalinity (Ic) for the C-P strata in eastern Gangdese are mostly 0.25-0.42 (very-low grade metamorphism) and a few 0.20-0.25 (low metamorphism). The Mesozoic and Cenozoic magmatism and related mineralization are very strong in the Gangdese, which may affect in some extent on indexes of illite crystalinity. In Tethyan Himalaya

Clays, common

USGS Publications Warehouse

Virta, R.L.

1998-01-01

Part of a special section on the state of industrial minerals in 1997. The state of the common clay industry worldwide for 1997 is discussed. Sales of common clay in the U.S. increased from 26.2 Mt in 1996 to an estimated 26.5 Mt in 1997. The amount of common clay and shale used to produce structural clay products in 1997 was estimated at 13.8 Mt.

Fire clay

USGS Publications Warehouse

Virta, R.L.

2011-01-01

The article discusses the latest developments in the fire clay industry, particularly in the U.S., as of June 2011. It claims that the leading fire clay producer in the U.S. is the state of Missouri. The other major producers include California, Texas and Washington. It reports that the use of heavy clay products made of fire clay like brick, cement and lightweight aggregate has increased slightly in 2010.

Towards an understanding of the role of clay minerals in crude oil formation, migration and accumulation

NASA Astrophysics Data System (ADS)

Wu, Lin Mei; Zhou, Chun Hui; Keeling, John; Tong, Dong Shen; Yu, Wei Hua

2012-12-01

This article reviews progress in the understanding of the role of clay minerals in crude oil formation, migration and accumulation. Clay minerals are involved in the formation of kerogen, catalytic cracking of kerogen into petroleum hydrocarbon, the migration of crude oil, and the continued change to hydrocarbon composition in underground petroleum reservoirs. In kerogen formation, clay minerals act as catalysts and sorbents to immobilize organic matter through ligand exchange, hydrophobic interactions and cation bridges by the mechanisms of Maillard reactions, polyphenol theory, selective preservation and sorptive protection. Clay minerals also serve as catalysts in acid-catalyzed cracking of kerogen into petroleum hydrocarbon through Lewis and Brønsted acid sites on the clay surface. The amount and type of clay mineral affect the composition of the petroleum. Brønsted acidity of clay minerals is affected by the presence and state of interlayer water, and displacement of this water is a probable driver in crude oil migration from source rocks. During crude oil migration and accumulation in reservoirs, the composition of petroleum is continually modified by interaction with clay minerals. The clays continue to function as sorbents and catalysts even while they are being transformed by diagenetic processes. The detail of chemical interactions and reaction mechanisms between clay minerals and crude oil formation remains to be fully explained but promises to provide insights with broader application, including catalytic conversion of biomass as a source of sustainable energy into the future.

Chemically-bonded brick production based on burned clay by means of semidry pressing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voroshilov, Ivan, E-mail: Nixon.06@mail.ru; Endzhievskaya, Irina, E-mail: icaend@mail.ru; Vasilovskaya, Nina, E-mail: icaend@mail.ru

We presented a study on the possibility of using the burnt rocks of the Krasnoyarsk Territory for production of chemically-bonded materials in the form of bricks which are so widely used in multistory housing and private house construction. The radiographic analysis of the composition of burnt rock was conducted and a modifier to adjust the composition uniformity was identified. The mixing moisture content was identified and optimal amount at 13-15% was determined. The method of semidry pressing has been chosen. The process of obtaining moldings has been theoretically proved; the advantages of chemically-bonded wall materials compared to ceramic brick weremore » shown. The production of efficient artificial stone based on material burnt rocks, which is comparable with conventionally effective ceramic materials or effective with cell tile was proved, the density of the burned clay-based cell tile makes up to 1630-1785 kg \\ m{sup 3}, with compressive strength of 13.6-20.0 MPa depending on the compression ratio and cement consumption, frost resistance index is F50, and the thermal conductivity in the masonry is λ = 0,459-0,546 W \\ m {sup *} °C. The clear geometric dimensions of pressed products allow the use of the chemically-bonded brick based on burnt clay as a facing brick.« less

The nature of porosity in organic-rich mudstones of the Upper Jurassic Kimmeridge Clay Formation, North Sea, offshore United Kingdom

USGS Publications Warehouse

Fishman, Neil S.; Hackley, Paul C.; Lowers, Heather; Hill, Ronald J.; Egenhoff, Sven O.; Eberl, Dennis D.; Blum, Alex E.

2012-01-01

Analyses of organic-rich mudstones from wells that penetrated the Upper Jurassic Kimmeridge Clay Formation, offshore United Kingdom, were performed to evaluate the nature of both organic and inorganic rock constituents and their relation to porosity in this world-class source rock. The formation is at varying levels of thermal maturity, ranging from immature in the shallowest core samples to mature in the deepest core samples. The intent of this study was to evaluate porosity as a function of both organic macerals and thermal maturity. At least four distinct types of organic macerals were observed in petrographic and SEM analyses and they all were present across the study area. The macerals include, in decreasing abundance: 1) bituminite admixed with clays; 2) elongate lamellar masses (alginite or bituminite) with small quartz, feldspar, and clay entrained within it; 3) terrestrial (vitrinite, fusinite, semifusinite) grains; and 4) Tasmanites microfossils. Although pores in all maceral types were observed on ion-milled surfaces of all samples, the pores (largely nanopores with some micropores) vary as a function of maceral type. Importantly, pores in the macerals do not vary systematically as a function of thermal maturity, insofar as organic pores are of similar size and shape in both the immature and mature Kimmeridge rocks. If any organic pores developed during the generation of hydrocarbons, they were apparently not preserved, possibly because of the highly ductile nature of much of the rock constituents of Kimmeridge mudstones (clays and organic material). Inorganic pores (largely micropores with some nanopores) have been observed in all Kimmeridge mudstones. These pores, particularly interparticle (i.e., between clay platelets), and intraparticle (i.e., in framboidal pyrite, in partially dissolved detrital K-feldspar, and in both detrital and authigenic dolomite) are noteworthy because they compose much of the observable porosity in the shales in both

Effects of bioleaching on the mechanical and chemical properties of waste rocks

NASA Astrophysics Data System (ADS)

Yin, Sheng-Hua; Wu, Ai-Xiang; Wang, Shao-Yong; Ai, Chun-Ming

2012-01-01

Bioleaching processes cause dramatic changes in the mechanical and chemical properties of waste rocks, and play an important role in metal recovery and dump stability. This study focused on the characteristics of waste rocks subjected to bioleaching. A series of experiments were conducted to investigate the evolution of rock properties during the bioleaching process. Mechanical behaviors of the leached waste rocks, such as failure patterns, normal stress, shear strength, and cohesion were determined through mechanical tests. The results of SEM imaging show considerable differences in the surface morphology of leached rocks located at different parts of the dump. The mineralogical content of the leached rocks reflects the extent of dissolution and precipitation during bioleaching. The dump porosity and rock size change under the effect of dissolution, precipitation, and clay transportation. The particle size of the leached rocks decreased due to the loss of rock integrity and the conversion of dry precipitation into fine particles.

February 2011 sensitive clay landslides in eastern Turkey

NASA Astrophysics Data System (ADS)

Akçar, N.; Yavuz, V.; Ivy-Ochs, S.; Fredin, O.; Schlunegger, F.

2016-12-01

The Çöllolar open pit mine is situated in the northwestern sector of the Elbistan basin, which is an intramontane basin located at a mean elevation of about 1200 m in the eastern Turkey. The basement rock in the basin is karstic limestone, which is overlain by a thick layer of clay (>100 m), followed by 20-50 m thick lignite series that is overlain by the 20-50 m thick gyttja sequence. These deposits are overlain by Quaternary deposits, comprising the top surfaces of the terraces of the Hurman River, which drains the surface and ground water from the surrounding hills to the northeast towards the center of the Elbistan basin. The lignite series in the basin has been excavated since early 1970's. In February 2011, two landslides in which 10 workers were killed, occurred in the Çöllolar mine. Of the two landslides, the 2nd and largest which covers an area of ca. 2.3 km2, was caused by the collapse of the northeastern wall of the open-pit mine. The failure was made of successive rearward collapses with the debris flowing into the open-pit. In this study, we focus on the sensitivity of the clays within the Quaternary deposits that seems led to instability and the trigger of the landslides based on the flow style of the movement and nature of the failure. To reveal these factors, we employed six boreholes and collected 64 undisturbed, 41 disturbed and 10 surface samples for the sedimentological and geotechnical analysis. Our results from this study show that Quaternary deposits are heterogeneous and have variable clay content. Mineralogically, most of these clays belong to the smectite group with high swelling potential. They are high plastic clays with high consolidation ratio. They have high shear and remolded shear strengths, thus low to medium sensitivity. Their sensitivity increases dramatically with increasing water content. During our analysis, we encountered a soft clay layer, which showed an over consolidation ratio of 10 and a strain softening response

Orbital identification of carbonate-bearing rocks on Mars

USGS Publications Warehouse

Ehlmann, B.L.; Mustard, J.F.; Murchie, S.L.; Poulet, F.; Bishop, J.L.; Brown, A.J.; Calvin, W.M.; Clark, R.N.; Des Marais, D.J.; Milliken, R.E.; Roach, L.H.; Roush, T.L.; Swayze, G.A.; Wray, J.J.

2008-01-01

Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Mars Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the Nili Fossae region. The carbonate is closely associated with both phyllosilicate-bearing and olivine-rich rock units and probably formed during the Noachian or early Hesperian era from the alteration of olivine by either hydrothermal fluids or near-surface water. The presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering, proposed to be characteristic of Hesperian Mars, did not destroy these carbonates and thus did not dominate all aqueous environments.

The Weathering of Rocks Under Humid Tropical Conditions.

DTIC Science & Technology

kaolinitic clay, the formation of gibbsite from the kaolinite , and the leaching of silica and iron-oxides. (Modified author abstract)...rhyolitic to andesitic lavas, tuffs and granophyre, under warm humid climatic conditions. The dominant minerals in the bauxite deposits are gibbsite ... kaolinite , quartz (also chalcedony), goethite, and hematite. The occurrence of bauxite is determined primarily by the parent rocks, which are typically fine

Numerical investigation of the seismic detectability of carbonate thin beds in the Boom Clay formation

NASA Astrophysics Data System (ADS)

Carcione, José M.; Gei, Davide

2016-07-01

The present study evaluates the capacity of the Boom Clay as a host rock for disposal purposes, more precisely its seismic characterization, which may assess its long-term performance to store radioactive wastes. Although the formation is relatively uniform and homogeneous, there are embedded thin layers of septaria (carbonates) that may affect the integrity of the Boom Clay. Therefore, it is essential to locate these geobodies. The seismic data to characterize the Boom Clay has been acquired at the Kruibeke test site. The inversion, which allowed us to obtain the anisotropy parameters and seismic velocities of the clay, is complemented with further information such as log and laboratory data. The attenuation properties have been estimated from equivalent formations (having similar composition and seismic velocities). The inversion yields quite consistent results although the symmetry of the medium is unusual but physically possible, since the anisotropy parameter ɛ is negative. According to a time-domain calculation of the energy velocity at four frequency bands up to 900 Hz, velocity increases with frequency, a behaviour described by the Zener model. Then, we use this model to describe anisotropy and anelasticity that are implemented into the equation of motion to compute synthetic seismograms in the space-time domain. The technique is based on memory variables and the Fourier pseudospectral method. We have computed reflection coefficients of the septaria thin layer. At normal incidence, the P-wave coefficient vanishes at specific thicknesses of the layer and there is no conversion to the S wave. For example, calculations at 600 Hz show that for thicknesses of 1 m the septarium can be detected more easily since the amplitudes are higher (nearly 0.8). Converted PS waves have a high amplitude at large offsets (between 30° and 80°) and can be useful to identify the target on this basis. Moreover, we have investigated the effect of septaria embedded in the Boom

Ball clay

USGS Publications Warehouse

Virta, R.L.

2000-01-01

Part of the 1999 Industrial Minerals Review. The state of the ball clay industry in 1999 is presented. Record highs in the sales and use of ball clay were attained in 1999 due to the continued strength of the U.S. economy. U.S. production was estimated at 1.25 million st for the year, with more than half of that amount mined in Tennessee. Details of the consumption, price, imports, and exports of ball clay in 1999 and the outlook for ball clay over the next few years are provided.

Clay for Little Fingers.

ERIC Educational Resources Information Center

Koster, Joan Bouza

1999-01-01

Discusses the renewed interest in clay as a modeling compound in early childhood programs; describes the nature of clay and presents a working vocabulary. Suggests methods of working with clay, including introducing clay to children, discovering its uses, clean up, firing clay, and finishing baked clay. Includes activity suggestions and…

The Fe-Rich Clay Microsystems in Basalt-Komatiite Lavas: Importance of Fe-Smectites for Pre-Biotic Molecule Catalysis During the Hadean Eon

NASA Astrophysics Data System (ADS)

Meunier, Alain; Petit, Sabine; Cockell, Charles S.; El Albani, Abderrazzak; Beaufort, Daniel

2010-06-01

During the Hadean to early Archean period (4.5-3.5 Ga), the surface of the Earth’s crust was predominantly composed of basalt and komatiite lavas. The conditions imposed by the chemical composition of these rocks favoured the crystallization of Fe-Mg clays rather than that of Al-rich ones (montmorillonite). Fe-Mg clays were formed inside chemical microsystems through sea weathering or hydrothermal alteration, and for the most part, through post-magmatic processes. Indeed, at the end of the cooling stage, Fe-Mg clays precipitated directly from the residual liquid which concentrated in the voids remaining in the crystal framework of the mafic-ultramafic lavas. Nontronite-celadonite and chlorite-saponite covered all the solid surfaces (crystals, glass) and are associated with tiny pyroxene and apatite crystals forming the so-called “mesostasis”. The mesostasis was scattered in the lava body as micro-settings tens of micrometres wide. Thus, every square metre of basalt or komatiite rocks was punctuated by myriads of clay-rich patches, each of them potentially behaving as a single chemical reactor which could concentrate the organics diluted in the ocean water. Considering the high catalytic potentiality of clays, and particularly those of the Fe-rich ones (electron exchangers), it is probable that large parts of the surface of the young Earth participated in the synthesis of prebiotic molecules during the Hadean to early Archean period through innumerable clay-rich micro-settings in the massive parts and the altered surfaces of komatiite and basaltic lavas. This leads us to suggest that Fe,Mg-clays should be preferred to Al-rich ones (montmorillonite) to conduct experiments for the synthesis and the polymerisation of prebiotic molecules.

Clay Houses

ERIC Educational Resources Information Center

Pedro, Cathy

2011-01-01

In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

10 CFR 960.3-1-2 - Diversity of rock types.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Diversity of rock types. 960.3-1-2 Section 960.3-1-2... NUCLEAR WASTE REPOSITORY Implementation Guidelines § 960.3-1-2 Diversity of rock types. Consideration... sites for characterization shall have different types of host rock. ...

10 CFR 960.3-1-2 - Diversity of rock types.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Diversity of rock types. 960.3-1-2 Section 960.3-1-2... NUCLEAR WASTE REPOSITORY Implementation Guidelines § 960.3-1-2 Diversity of rock types. Consideration... sites for characterization shall have different types of host rock. ...

10 CFR 960.3-1-2 - Diversity of rock types.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Diversity of rock types. 960.3-1-2 Section 960.3-1-2... NUCLEAR WASTE REPOSITORY Implementation Guidelines § 960.3-1-2 Diversity of rock types. Consideration... sites for characterization shall have different types of host rock. ...

10 CFR 960.3-1-2 - Diversity of rock types.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Diversity of rock types. 960.3-1-2 Section 960.3-1-2... NUCLEAR WASTE REPOSITORY Implementation Guidelines § 960.3-1-2 Diversity of rock types. Consideration... sites for characterization shall have different types of host rock. ...

Ground Truthing Orbital Clay Mineral Observations with the APXS Onboard Mars Exploration Rover Opportunity

NASA Technical Reports Server (NTRS)

Schroeder, C.; Gellert, R.; VanBommel, S.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. S.; Yen, A. S.

2016-01-01

NASA's Mars Exploration Rover Opportunity has been exploring approximately 22 km diameter Endeavour crater since 2011. Its rim segments predate the Hesperian-age Burns formation and expose Noachian-age material, which is associated with orbital Fe3+-Mg-rich clay mineral observations [1,2]. Moving to an orders of magnitude smaller instrumental field of view on the ground, the clay minerals were challenging to pinpoint on the basis of geochemical data because they appear to be the result of near-isochemical weathering of the local bedrock [3,4]. However, the APXS revealed a more complex mineral story as fracture fills and so-called red zones appear to contain more Al-rich clay minerals [5,6], which had not been observed from orbit. These observations are important to constrain clay mineral formation processes. More detail will be added as Opportunity is heading into her 10th extended mission, during which she will investigate Noachian bedrock that predates Endeavour crater, study sedimentary rocks inside Endeavour crater, and explore a fluid-carved gully. ESA's ExoMars rover will land on Noachian-age Oxia Planum where abundant Fe3+-Mg-rich clay minerals have been observed from orbit, but the story will undoubtedly become more complex once seen from the ground.

Green Clay Minerals

NASA Astrophysics Data System (ADS)

Velde, B.

2003-12-01

in the silicate (clay mineral in our case) structure, the specific bonding of these ions, and other factors. In fact, the reasons for coloration are not known completely, but it is certain that a combination of Fe2+ and Fe3+ ions is necessary to give a nice green color to clays. In the green clay minerals discussed here, the colors vary greatly as seen under the optical microscope (not always the same as the one seen in hand specimen). Yellow to blue-green hues can be found. However, for the moment, no clear relation between iron content, iron valence ratio, or other factors such as minor transition element concentrations can be found to explain the greenness of green clay minerals. The fact that a clay is green just indicates a combination of the two oxidation states of iron. The color, however, indicates the key to the formation in nature of green clay minerals.Green clay minerals are in general the product of "mixed valence" conditions of formation, most often in a situation where some iron is reduced from Fe3+ and enters into a silicate mineral structure. In general, iron would rather be an oxide when it is in the trivalent state. The moment iron is reduced to a divalent state under surface or near-surface conditions, it looks for a silicate, sulfide, or carbonate to hide in. The reverse is also true, of course. When a silicate is oxidized, Fe2+ becoming Fe3+, the iron begins to group together in oxide clumps and eventually exits the silicate structure. This is seen in thin section in altered rocks (weathering or hydrothermal action). The production of trivalent, oxidized iron usually results in a brownish or orange mineral.If the geology of the formation of green silicate minerals is relatively well defined, especially at near surface or surface conditions, the question remains how much of the iron is in a reduced oxidation state and how? In the case of reduction of iron in surface environments: if most of the iron goes to Fe2+, one mineral is formed; if only

Mineral and energy resources of the Roswell Resource Area, East-Central New Mexico

USGS Publications Warehouse

Bartsch-Winkler, Susan B.; Donatich, Alessandro J.

1995-01-01

The sedimentary formations of the Roswell Resource Area have significant mineral and energy resources. Some of the pre-Pennsylvanian sequences in the Northwestern Shelf of the Permian Basin are oil and gas reservoirs, and Pennsylvanian rocks in Tucumcari Basin are reservoirs of oil and gas as well as source rocks for oil and gas in Triassic rocks. Pre-Permian rocks also contain minor deposits of uranium and vanadium, limestone, and gases. Hydrocarbon reservoirs in Permian rocks include associated gases such as carbon dioxide, helium, and nitrogen. Permian rocks are mineralized adjacent to the Lincoln County porphyry belt, and include deposits of copper, uranium, manganese, iron, polymetallic veins, and Mississippi-Valley-type lead-zinc. Industrial minerals in Permian rocks include fluorite, barite, potash, halite, polyhalite, gypsum, anhydrite, sulfur, limestone, dolomite, brine deposits (iodine and bromine), aggregate (sand), and dimension stone. Doubly terminated quartz crystals, called 'Pecos diamonds' and collected as mineral specimens, occur in Permian rocks along the Pecos River. Mesozoic sedimentary rocks are hosts for copper, uranium, and small quantities of gold-silver-tellurium veins, as well as significant deposits of oil and gas, carbon dioxide, asphalt, coal, and dimension stone. Mesozoic rocks contain limited amounts of limestone, gypsum, petrified wood, and clay. Tertiary rocks host ore deposits commonly associated with intrusive rocks, including platinum-group elements, iron skarns, manganese, uranium and vanadium, molybdenum, polymetallic vein deposits, gold-silver-tellurium veins, and thorium-rare-earth veins. Museum-quality quartz crystals are associated with Tertiary intrusive rocks. Industrial minerals in Tertiary rocks include fluorite, vein- and bedded-barite, caliche, limestone, and aggregate. Tertiary and Quaternary sediments host important placer deposits of gold and titanium, and occurrences of silver and uranium. Important industrial

Fault imprint in clay units: magnetic fabric, structural and mineralogical signature

NASA Astrophysics Data System (ADS)

Moreno, Eva; Homberg, Catherine; Schnyder, Johann; Person, Alain; du Peloux1, Arthur; Dick, Pierre

2014-05-01

Fault-induced deformations in clay units can be difficult to decipher because strain markers are not always visible at outcrop scale or using geophysical methods. Previous studies have indicated that the anisotropy of magnetic susceptibility (ASM) provides a powerful and rapid technique to investigate tectonic deformation in clay units even when they appear quite homogenous and undeformed at the outcrop scale (Lee et al. 1990, Mattei et al. 1997). We report here a study based on ASM, structural analysis and magnetic and clay mineralogy from two boreholes (TF1 and ASM1)drilled horizontally in the Experimental Station of Tournemire of the Institute for Radiological Protection and Nuclear Safety (IRSN) in Aveyron (France). The boreholes intersect a N-S trending strike-slip fault from west to east. The ASM study indicates the evolution of the magnetic fabric from the undeformed host rock to the fault core. Also, all the fractures cutting the studied interval of the core have been measured as well as the slip vectors which are generally well preserved. In the two boreholes, the undeformed sediments outside the fault zone are characterized by an oblate fabric, a sub-vertical minimum susceptibility axis (k3) perpendicular to the bedding plane and without magnetic lineation. Within the fault zone, a tilt in the bedding plane has been observed in two boreholes TF1 and ASM1. In addition, in the TF1 core, the fault area presents a tectonic fabric characterized by a triaxial AMS ellipsoid. Moreover, the magnetic lineation increases and k3 switches from a vertical to a sub-horizontal plane. This kind of fabric has not been observed in borehole ASM1. The structural analysis of the individual fractures making the fault zone indicates a complex tectonic history with different imprint in the two fault segments cut by the two boreholes. The large majority of fractures correspond to dextral strike-slip faults but normal and reverse movements were observed and are more or less

Modified clay sorbents

DOEpatents

Fogler, H. Scott; Srinivasan, Keeran R.

1990-01-01

A novel modified clay sorbent and method of treating industrial effluents to remove trace pollutants, such as dioxins, biphenyls, and polyaromatics such as benzo(a)pyrene and pentachlorophenol. The novel clay sorbent has a composite structure in which the interlayer space of an expandable clay, such as smectite, is filled with polyvalent or multivalent inorganic cations which forces weaker surfactant cations to locate on the surface of the clay in such an orientation that the resulting composite is hydrophilic in nature. A specific example is cetylpyridinium-hydroxy aluminum-montmorillonite. In certain embodiments, a non-expanding clay, such as kaolinite, is used and surfactant cations are necessarily located on an external surface of the clay. A specific example is cetylpyridinium-kaolinite.

Clays on Mars: Review of chemical and mineralogical evidence

NASA Technical Reports Server (NTRS)

Banin, Amos; Gooding, James L.

1991-01-01

Mafic igneous bedrock is inferred for Mars, based on spectrophotometric evidence for pyroxene (principally in optically dark areas of the globe) and the pyroxenite-peridotite petrology of shergottite nakhlite chassignite (SNC) meteorites. Visible and infrared spectra of reddish-brown surface fines (which dominate Martian bright areas) indicate ferric iron and compare favorably (though not uniquely) with spectra of palagonitic soils. Laboratory studies of SNC's and Viking Lander results support a model for Martian soil based on chemical weathering of mafic rocks to produce layer structured silicates (clay minerals), salts, and iron oxides.

Report on International Collaboration Involving the FE Heater and HG-A Tests at Mont Terri

DOE Office of Scientific and Technical Information (OSTI.GOV)

Houseworth, Jim; Rutqvist, Jonny; Asahina, Daisuke

Nuclear waste programs outside of the US have focused on different host rock types for geological disposal of high-level radioactive waste. Several countries, including France, Switzerland, Belgium, and Japan are exploring the possibility of waste disposal in shale and other clay-rich rock that fall within the general classification of argillaceous rock. This rock type is also of interest for the US program because the US has extensive sedimentary basins containing large deposits of argillaceous rock. LBNL, as part of the DOE-NE Used Fuel Disposition Campaign, is collaborating on some of the underground research laboratory (URL) activities at the Mont Terrimore » URL near Saint-Ursanne, Switzerland. The Mont Terri project, which began in 1995, has developed a URL at a depth of about 300 m in a stiff clay formation called the Opalinus Clay. Our current collaboration efforts include two test modeling activities for the FE heater test and the HG-A leak-off test. This report documents results concerning our current modeling of these field tests. The overall objectives of these activities include an improved understanding of and advanced relevant modeling capabilities for EDZ evolution in clay repositories and the associated coupled processes, and to develop a technical basis for the maximum allowable temperature for a clay repository.« less

The formation of technic soil in a revegetated uranium ore waste rock pile (Limousin, France)

NASA Astrophysics Data System (ADS)

Boekhout, Flora; Gérard, Martine; Kanzari, Aisha; Calas, Georges; Descostes, Michael

2014-05-01

Mining took place in France between 1945 and 2001 during which time ~210 different sites were exploited and/or explored. A total of 76 Kt of uranium was produced, 52 Mt of ore was extracted, but also 200 Mt of waste rocks was produced, the majority of which, with uranium levels corresponding to the natural environment. So far, the processes of arenisation and technic soil formation in waste rock piles are not well understood but have important implications for understanding the environmental impact and long-term speciation of uranium. Understanding weathering processes in waste rock piles is essential to determine their environmental impact. The main objectives of this work are to assess 1) the micromorphological features and neo-formed U-bearing phases related to weathering and 2) the processes behind arenisation of the rock pile. The site that was chosen is the Vieilles Sagnes waste rock pile in Fanay (Massif Central France) that represents more or less hydrothermally altered granitic rocks that have been exposed to weathering since the construction of the waste rock pile approximately 50 years ago. Two trenches were excavated to investigate the vertical differentiation of the rock pile. This site serves as a key location for studying weathering processes of waste rock piles, as it has not been reworked after initial construction and has therefore preserved information on the original mineralogy of the waste rock pile enabling us to access post emplacement weathering processes. The site is currently overgrown by moss, meter high ferns and small trees. At present day the rock pile material can be described as hydrothermally altered rocks and rock fragments within a fine-grained silty clay matrix exposed to surface conditions and weathering. A sandy "paleo" technic soil underlies the waste rock pile and functions as a natural liner by adsorption of uranium on clay minerals. Post-mining weathering of rock-pile material is superimposed on pre-mining hydrothermal and

Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martins, Marcel G.; Martins, Daniel O.T.A.; Carvalho, Beatriz L.C. de

2015-08-15

In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad{sup +}) and two binuclear coordination compounds, [Ni(valpn)Ln]{sup 3+}, where H{sub 2}valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=Gd{sup III}; Dy{sup III}. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar spacemore » of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest.« less

Interaction of ordinary Portland cement and Opalinus Clay: Dual porosity modelling compared to experimental data

NASA Astrophysics Data System (ADS)

Jenni, A.; Gimmi, T.; Alt-Epping, P.; Mäder, U.; Cloet, V.

2017-06-01

Interactions between concrete and clays are driven by the strong chemical gradients in pore water and involve mineral reactions in both materials. In the context of a radioactive waste repository, these reactions may influence safety-relevant clay properties such as swelling pressure, permeability or radionuclide retention. Interfaces between ordinary Portland cement and Opalinus Clay show weaker, but more extensive chemical disturbance compared to a contact between low-pH cement and Opalinus Clay. As a consequence of chemical reactions porosity changes occur at cement-clay interfaces. These changes are stronger and may lead to complete pore clogging in the case of low-pH cements. The prediction of pore clogging by reactive transport simulations is very sensitive to the magnitude of diffusive solute fluxes, cement clinker chemistry, and phase reaction kinetics. For instance, the consideration of anion-depleted porosity in clays substantially influences overall diffusion and pore clogging at interfaces. A new concept of dual porosity modelling approximating Donnan equilibrium is developed and applied to an ordinary Portland cement - Opalinus Clay interface. The model predictions are compared with data from the cement-clay interaction (CI) field experiment in the Mt Terri underground rock laboratory (Switzerland), which represent 5 y of interaction. The main observations such as the decalcification of the cement at the interface, the Mg enrichment in the clay detached from the interface, and the S enrichment in the cement detached from the interface, are qualitatively predicted by the new model approach. The model results reveal multiple coupled processes that create the observed features. The quantitative agreement of modelled and measured data can be improved if uncertainties of key input parameters (tortuosities, reaction kinetics, especially of clay minerals) can be reduced.

Numerical modelling of fluid-rock interactions: Lessons learnt from carbonate rocks diagenesis studies

NASA Astrophysics Data System (ADS)

Nader, Fadi; Bachaud, Pierre; Michel, Anthony

2015-04-01

Quantitative assessment of fluid-rock interactions and their impact on carbonate host-rocks has recently become a very attractive research topic within academic and industrial realms. Today, a common operational workflow that aims at predicting the relevant diagenetic processes on the host rocks (i.e. fluid-rock interactions) consists of three main stages: i) constructing a conceptual diagenesis model including inferred preferential fluids pathways; ii) quantifying the resulted diagenetic phases (e.g. depositing cements, dissolved and recrystallized minerals); and iii) numerical modelling of diagenetic processes. Most of the concepts of diagenetic processes operate at the larger, basin-scale, however, the description of the diagenetic phases (products of such processes) and their association with the overall petrophysical evolution of sedimentary rocks remain at reservoir (and even outcrop/ well core) scale. Conceptual models of diagenetic processes are thereafter constructed based on studying surface-exposed rocks and well cores (e.g. petrography, geochemistry, fluid inclusions). We are able to quantify the diagenetic products with various evolving techniques and on varying scales (e.g. point-counting, 2D and 3D image analysis, XRD, micro-CT and pore network models). Geochemical modelling makes use of thermodynamic and kinetic rules as well as data-bases to simulate chemical reactions and fluid-rock interactions. This can be through a 0D model, whereby a certain process is tested (e.g. the likelihood of a certain chemical reaction to operate under specific conditions). Results relate to the fluids and mineral phases involved in the chemical reactions. They could be used as arguments to support or refute proposed outcomes of fluid-rock interactions. Coupling geochemical modelling with transport (reactive transport model; 1D, 2D and 3D) is another possibility, attractive as it provides forward simulations of diagenetic processes and resulting phases. This

Fire clay

USGS Publications Warehouse

Virta, R.L.

2006-01-01

In 2005, six companies mined fire clay in Missouri, Ohio and South Carolina. Production was estimate to be 300 kt with a value of $8.3 million. Missouri was the leading producer state followed by Ohio and South Carolina. For the third consecutive year, sales and use of fire clays have been relatively unchanged. For the next few years, sales of fire clay is forecasted to remain around 300 kt/a.

Dolomitization of felsic volcaniclastic rocks in continental strata: A study from the Lower Cretaceous of the A'nan Sag in Er'lian Basin, China

NASA Astrophysics Data System (ADS)

Zhu, Shifa; Yue, Hui; Zhu, Xiaomin; Sun, Shuyang; Wei, Wei; Liu, Xin; Jia, Ye

2017-05-01

Dolomitization of fine-grained volcaniclastic rocks is common in the Lower Cretaceous of the A'nan Sag in the Er'lian Basin of China. Analysis of core samples shows that the organic-rich volcaniclastic rocks are mainly composed of reworked felsic volcanic materials and terrigenous clay minerals. The fine-grained volcaniclastic rocks can be divided into four types: volcaniclastic rocks without carbonatization, volcaniclastic rocks with ferroan dolomites, dolomitized and calcified volcaniclastic rocks, and calcified volcaniclastic rocks. The parent rocks of the volcaniclastic rocks have high silicon and potassium contents and low iron and magnesium contents, and are probably felsic magma of the calc-alkaline series. The average values of δ13CPDB of the carbonate minerals are about 3.13‰; the average values of δ18OPDB are about - 16.74‰. The compositions of C and O isotopes are probably influenced by bacterial methanogenesis. Iron, magnesium, and calcium are probably derived from illitization of terrigenous smectite. A model for dolomitization of felsic volcaniclastic rock is proposed, including three stages: 1) mixed sedimentation and bacterial methanogenesis (< 75 °C); 2) transformation of clay minerals (> 70 °C) and dolomitization (75 to 97 °C); and 3) dissolution. Late dissolution of authigenic carbonate minerals, creating abundant secondary pores, is significant for hydrocarbon accumulation.

An experimental study of the effects of adsorbing and non-adsorbing gases on friction and permeability evolution in clay-rich fault gouge

NASA Astrophysics Data System (ADS)

Lisabeth, H. P.; Zoback, M. D.

2017-12-01

Understanding the flow of fluids through fractures in clay-rich rocks is fundamental to a number of geoengineering enterprises, including development of unconventional hydrocarbon resources, nuclear waste storage and geological carbon sequestration. High clay content tends to make rocks plastic, low-porosity and anisotropic. In addition, some gasses adsorb to clay mineral surfaces, resulting in swelling and concomitant changes in physical properties. These complexities can lead to coupled behaviors that render prediction of fluid behavior in the subsurface difficult. We present the results of a suite of triaxial experiments on binary mixtures of quartz and illite grains to separate and quantify the effects of hydrostatic pressure, differential stress, clay content and gas chemistry on the evolution of mechanical and hydraulic characteristics of the gouge material during deformation. Tests are run on saw-cut samples prepared with gouge at 20 MPa confining pressure, 10 MPa pore pressure and at room temperature. Argon or carbon dioxide is used as pore fluid. Sample permeability, stress and strain are monitored continuously during hydrostatic and axial deformation. We find that pressure and shearing both lead to reductions in permeability. Adsorbing gas leads to swelling and promotes permeability reduction, but appears to have no effect on frictional properties. These results indicate that the seal integrity of clay-rich caprocks may not be compromised by shear deformation, and that depletion and shear deformation of unconventional reservoirs is expected to result in production declines.

Mineral chemistry of magnetite from magnetite-apatite mineralization and their host rocks: examples from Kiruna, Sweden, and El Laco, Chile

NASA Astrophysics Data System (ADS)

Broughm, Shannon G.; Hanchar, John M.; Tornos, Fernando; Westhues, Anne; Attersley, Samuel

2017-12-01

Interpretation of the mineralizing environment of magnetite-apatite deposits remains controversial with theories that include a hydrothermal or magmatic origin or a combination of those two processes. To address this controversy, we have analyzed the trace element content of magnetite from precisely known geographic locations and geologic environments from the Precambrian magnetite-apatite ore and host rocks in Kiruna, Sweden, and the Pliocene-Holocene El Laco volcano in the Atacama desert of Chile. Magnetite samples from Kiruna have low trace element concentrations with little chemical variation between the ore, host, and related intrusive rocks. Magnetite from andesite at El Laco, and dacite from the nearby Láscar volcano, has high trace element concentrations typical of magmatic magnetite. El Laco ore magnetite have low trace element concentrations and displays growth zoning in incompatible elements (Si, Ca, and Ce), compatible elements (Mg, Al, and Mn), large-ion lithophile element (Sr), and high field strength element (Y, Nb, and Th). The El Laco ore magnetite are similar in composition to magnetite that has been previously interpreted to have crystallized from hydrothermal fluids; however, there is a significant difference in the internal zoning patterns. At El Laco, each zoned element is either enriched or depleted in the same layers, suggesting the magnetite crystallized from a volatile-rich, iron-oxide melt. In general, the compositions of magnetite from these two deposits plot in very wide fields that are not restricted to the proposed fields in published discriminant diagrams. This suggests that the use of these diagrams and genetic models based on them should be used with caution.

Mineralogical compositions of fault rocks from surface ruptures of Wenchuan earthquake and implication of mineral transformation during the seismic cycle along Yingxiu-Beichuan fault, Sichuan Province, China

NASA Astrophysics Data System (ADS)

Dang, Jiaxiang; Zhou, Yongsheng; He, Changrong; Ma, Shengli

2018-06-01

There are two co-seismic bedrock surface ruptures from the Mw 7.9 Wenchuan earthquake in the northern and central parts of the Beichuan-Yingxiu fault, Sichuan Province, southwest China. In this study, we report on the macrostructure of the fault rocks and results from X-ray powder diffraction analysis of minerals from rocks in the fault zone. The most recent fault gouge (the gouge produced by the most recent co-seismic fault movement) in all the studied outcrops is dark or grayish-black, totally unconsolidated and ultrafine-grained. Older fault gouges in the same outcrops are grayish or yellowish and weakly consolidated. X-ray powder diffraction analysis results show that mineral assemblages in both the old fault gouge and the new fault gouge are more complicated than the mineral assemblages in the bedrock as the fault gouge is rich in clay minerals. The fault gouge inherited its major rock-forming minerals from the parent rocks, but the clay minerals in the fault gouge were generated in the fault zone and are therefore authigenic and synkinematic. In profiles across the fault, clay mineral abundances increase as one traverses from the bedrock to the breccia to the old gouge and from the old gouge to the new gouge. Quartz and illite are found in all collected gouge samples. The dominant clay minerals in the new fault gouge are illite and smectite along the northern part of the surface rupture and illite/smectite mixed-layer clay in the middle part of the rupture. Illite/smectite mixed-layer clay found in the middle part of the rupture indicates that fault slip was accompanied by K-rich fluid circulation. The existence of siderite, anhydrite, and barite in the northern part of the rupture suggests that fault slip at this locality was accompanied by acidic fluids containing ions of Fe, Ca, and Ba.

Changes in geophysical properties caused by fluid injection into porous rocks: analytical models: Geophysical changes in porous rocks

DOE PAGES

Pride, Steven R.; Berryman, James G.; Commer, Michael; ...

2016-08-30

Analytical models are provided that describe how the elastic compliance, electrical conductivity, and fluid-flow permeability of rocks depend on stress and fluid pressure. In order to explain published laboratory data on how seismic velocities and electrical conductivity vary in sandstones and granites, the models require a population of cracks to be present in a possibly porous host phase. The central objective is to obtain a consistent mean-field analytical model that shows how each modeled rock property depends on the nature of the crack population. We describe the crack populations by a crack density, a probability distribution for the crack aperturesmore » and radii, and the averaged orientation of the cracks. The possibly anisotropic nature of the elasticity, conductivity, and permeability tensors is allowed for; however, only the isotropic limit is used when comparing to laboratory data. For the transport properties of conductivity and permeability, the percolation effect of the crack population linking up to form a connected path across a sample is modeled. But, this effect is important only in crystalline rock where the host phase has very small conductivity and permeability. In general, the importance of the crack population to the transport properties increases as the host phase becomes less conductive and less permeable.« less

Changes in geophysical properties caused by fluid injection into porous rocks: analytical models: Geophysical changes in porous rocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pride, Steven R.; Berryman, James G.; Commer, Michael

Analytical models are provided that describe how the elastic compliance, electrical conductivity, and fluid-flow permeability of rocks depend on stress and fluid pressure. In order to explain published laboratory data on how seismic velocities and electrical conductivity vary in sandstones and granites, the models require a population of cracks to be present in a possibly porous host phase. The central objective is to obtain a consistent mean-field analytical model that shows how each modeled rock property depends on the nature of the crack population. We describe the crack populations by a crack density, a probability distribution for the crack aperturesmore » and radii, and the averaged orientation of the cracks. The possibly anisotropic nature of the elasticity, conductivity, and permeability tensors is allowed for; however, only the isotropic limit is used when comparing to laboratory data. For the transport properties of conductivity and permeability, the percolation effect of the crack population linking up to form a connected path across a sample is modeled. But, this effect is important only in crystalline rock where the host phase has very small conductivity and permeability. In general, the importance of the crack population to the transport properties increases as the host phase becomes less conductive and less permeable.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, H.H.; Li, L.; Zheng, L.

Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding amore » variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.« less

Clays in prebiological chemistry

NASA Technical Reports Server (NTRS)

Rao, M.; Oro, J.; Odom, D. G.

1980-01-01

The ways in which clays have been utilized in studies of prebiological chemistry are reviewed, and an assessment is given of the possible role of clays in prebiological systems. The adsorption of organic molecules on clays has been demonstrated, as has the synthesis of bioorganic monomers in the presence of clays. For instance, amino acids, purines and pyrimidines have been obtained from carbon monoxide and nitric acid in the presence of clays at relatively high temperatures (250-325 C). The oligomerization of biochemical monomers, mediated by clays, has also been shown to result in the formation of polymer molecules basic to life. Clays have also been found to affect the condensation of mononucleotides to oligonucleotides.

Retention of contaminants Cd and Hg adsorbed and intercalated in aluminosilicate clays: A first principles study

NASA Astrophysics Data System (ADS)

Crasto de Lima, F. D.; Miwa, R. H.; Miranda, Caetano R.

2017-11-01

Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ˜20 and ˜130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays.

Hydro-mechanical properties of the Red Salt Clay (T4) - Relevancy of the minimum stress criterion for barrier integrity

NASA Astrophysics Data System (ADS)

Minkley, W.; Popp, T.; Salzer, K.; Gruner, M.; Böttge, V.

The so-called Red Salt Clay (T4) is deposited as clay-rich clastic sediment at the base of the Aller-series forming a persistent lateral layer of up to 20 m thickness above the lower Zechstein-series. The clay layers may act as a protective shield in the hanging wall of gas storages or underground repositories in salt formations, thus resulting in a multi-barrier system. As a proof of its reliability comprehensive hydro-mechanical investigations were performed on clay samples recovered at different sites in Germany. Most important, rock tightness against various fluids was confirmed in the lab and field-scale. Remarkably, only if the fluid pressure equalises the acting minimal stress (i.e. violence of the “minimum stress criterion”) a significant increase of permeability is observed (“pathway dilatation”) but no macro-frac. However, the material properties from different locations showed a significant variability according to different burial depths. Thus the Red Salt Clay may act as natural analogue, representing the material variability of various indurated clays. In addition, the existing knowledge gained from practical mining activities can be used to evaluate extreme in situ loading conditions.

K-Ar age constrains on chemically weathered granitic basement rocks (saprolites) in Scandinavia

NASA Astrophysics Data System (ADS)

Margreth, Annina; Fredin, Ola; Viola, Giulio; Knies, Jochen; Sørlie, Ronald; Lie, Jan-Erik; Margrethe Grandal, Else; Zwingmann, Horst; Vogt, Christoph

2017-04-01

Remnants of in-situ weathered bedrock, saprolite, are found in several locations in Scandinavia. Saprolites contain important information about past climate conditions and landscape evolution, although their age and genesis are commonly difficult to constrain. It is generally thought that clay-poor, coarse-grained (arêne) saprolites, mostly occurring as thin regolith blankets or in larger outcrops, formed in temperate climate during the Cenozoic, whereas clay-rich (argillic) saprolites, commonly restricted to small, fracture-bounded outcrops, formed in (sub-)tropical climate during the Mesozoic. Recent methodological and conceptual advances in K-Ar dating of illite-bearing fault rocks have been applied to date clay-rich saprolites. To test the K-Ar dating technique for saprolites, we first selected an offshore site in the Viking Graben of the North Sea, where weathered and fractured granitic basement highs have been drilled during petroleum exploration, and an abandoned kaolin mine in Southern Sweden. Both targets provide independent age control through the presence of overlying Mesozoic sedimentary rocks. Clay-rich saprolites occurring in fractured basement rocks were additionally sampled in a joint valley landscape on the southwestern coast of Norway, which can be regarded as the possible onland correlative to the offshore basement high. In order to offer a sound interpretation of the obtained K-Ar ages, the mineralogical and chemical composition of the saprolites requires a thorough characterization. Scanning electron microscopy of thin sections, integrated by XRD and XRF analysis, reveals the progressive transformation of primary granitic rock minerals into secondary clay minerals. The authigenesis of illite is particularly important to understand, since it is the only K-bearing clay mineral that can be dated by the K-Ar method. K-feldspars and mica are the common primary K-bearing minerals, from which illite can be formed. While progressive leaching of

Comparison of rapid methods for chemical analysis of milligram samples of ultrafine clays

USGS Publications Warehouse

Rettig, S.L.; Marinenko, J.W.; Khoury, Hani N.; Jones, B.F.

1983-01-01

Two rapid methods for the decomposition and chemical analysis of clays were adapted for use with 20–40-mg size samples, typical amounts of ultrafine products (≤0.5-µm diameter) obtained by modern separation methods for clay minerals. The results of these methods were compared with those of “classical” rock analyses. The two methods consisted of mixed lithium metaborate fusion and heated decomposition with HF in a closed vessel. The latter technique was modified to include subsequent evaporation with concentrated H2SO4 and re-solution in HCl, which reduced the interference of the fluoride ion in the determination of Al, Fe, Ca, Mg, Na, and K. Results from the two methods agree sufficiently well with those of the “classical” techniques to minimize error in the calculation of clay mineral structural formulae. Representative maximum variations, in atoms per unit formula of the smectite type based on 22 negative charges, are 0.09 for Si, 0.03 for Al, 0.015 for Fe, 0.07 for Mg, 0.03 for Na, and 0.01 for K.

Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock

DOE PAGES

Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L.; ...

2016-10-14

A significant fraction (~ 20%) of microbial life is found in the terrestrial deep subsurface, yet the metabolic processes extant in those environments are poorly understood. Here we show that H 2, injected into the Opalinus Clay formation in a borehole located 300 meters below the surface, fuels a community of microorganisms with interconnected metabolisms. Metagenomic binning and metaproteomic analysis reveal a complete carbon cycle, driven by autotrophic hydrogen oxidizers. Dead biomass from these organisms is a substrate for a fermenting bacterium that produces acetate as a product. In turn, complete oxidizer heterotrophic sulfate- reducing bacteria utilize acetate and oxidizemore » it to CO 2, closing the cycle. This metabolic reconstruction sheds light onto a hydrogen-driven carbon cycle, and a sunlight-independent ecosystem in the deep subsurface.« less

Petrogenesis of cataclastic rocks within the San Andreas fault zone of Southern California U.S.A.

NASA Astrophysics Data System (ADS)

Lawford Anderson, J.; Osborne, Robert H.; Palmer, Donald F.

1980-08-01

This paper petrologically characterizes cataclastic rocks derived from four sites within the San Andreas fault zone of southern California. In this area, the fault traverses an extensive plutonic and metamorphic terrane and the principal cataclastic rock formed at these upper crustal levels is unindurated gouge derived from a range of crystalline rocks including diorite, tonalite, granite, aplite, and pegmatite. The mineralogical nature of this gouge is decidedly different from the "clay gouge" reported by Wu (1975) for central California and is essentially a rock flour with a quartz, feldspar, biotite, chlorite, amphibole, epidote and oxide mineralogy representing the milled-down equivalent of the original rock. Clay development is minor (less than 4 wt. %) to nonexistent and is exclusively kaolinite. Alterations involve hematitic oxidation, chlorite alteration on biotite and amphibole, and local introduction of calcite. Electron microprobe analysis showed that in general the major minerals were not reequilibrated with the pressure—temperature regime imposed during cataclasis. Petrochemically, the form of cataclasis that we have investigated is largely an isochemical process. Some hydration occurs but the maximum amount is less than 2.2% added H 2O. Study of a 375 m deep core from a tonalite pluton adjacent to the fault showed that for Si, Al, Ti, Fe, Mg, Mn, K, Na, Li, Rb, and Ba, no leaching and/or enrichment occurred. Several samples experienced a depletion in Sr during cataclasis while lesser number had an enrichment of Ca (result of calcite veining). Texturally, the fault gouge is not dominated by clay-size material but consists largely of silt and fine sand-sized particles. An intriguing aspect of our work on the drill core is a general decrease in particulate size with depth (and confining pressure) with the predominate shifting sequentially from fine sand to silt-size material. The original fabric of these rocks is commonly not disrupted during the

Microstructural record of pressure solution and crystal plastic deformation in carbonate fault rocks from a shallow crustal strike-slip fault, Northern Calcareous Alps (Austria)

NASA Astrophysics Data System (ADS)

Bauer, Helene; Rogowitz, Anna; Grasemann, Benhard; Decker, Kurt

2017-04-01

This study presents microstructural investigations of natural carbonate fault rocks that formed by a suite of different deformation processes, involving hydro-fracturing, dissolution-precipitation creep and cataclasis. Some fault rocks show also clear indications of crystal plastic deformation, which is quite unexpected, as the fault rocks were formed in an upper crustal setting, raising the question of possible strongly localised, low temperature ductile deformation in carbonate rocks. The investigated carbonate fault rocks are from an exhumed, sinistral strike-slip fault at the eastern segment of the Salzachtal-Ennstal-Mariazell-Puchberg (SEMP) fault system in the Northern Calcareous Alps (Austria). The SEMP fault system formed during eastward lateral extrusion of the Eastern Alps in the Oligocene to Lower Miocene. Based on vitrinite reflectance data form intramontane Teritary basins within the Northern Calcareous Alps, a maximum burial depth of 4 km for the investigated fault segment is estimated. The investigated fault accommodated sinistral slip of several hundreds of meters. Microstructural analysis of fault rocks includes scanning electron microscopy, optical microscopy and electron backscattered diffraction mapping. The data show that fault rocks underwent various stages of evolution including early intense veining (hydro-fracturing) and stylolite formation reworked by localised shear zones. Cross cutting relationship reveals that veins never cross cut clay seams accumulated along stylolites. We conclude that pressure solution processes occured after hydro-fracturing. Clay enriched zones localized further deformation, producing a network of small-scale clay-rich shear zones of up to 1 mm thickness anastomosing around carbonate microlithons, varying from several mm down to some µm in size. Clay seams consist of kaolinit, chlorite and illite matrix and form (sub) parallel zones in which calcite was dissolved. Beside pressure solution, calcite microlithons

Heterostructured nanohybrid of zinc oxide-montmorillonite clay.

PubMed

Hur, Su Gil; Kim, Tae Woo; Hwang, Seong-Ju; Hwang, Sung-Ho; Yang, Jae Hun; Choy, Jin-Ho

2006-02-02

We have synthesized heterostructured zinc oxide-aluminosilicate nanohybrids through a hydrothermal reaction between the colloidal suspension of exfoliated montmorillonite nanosheets and the sol solution of zinc acetate. According to X-ray diffraction, N2 adsorption-desorption isotherm, and field emission-scanning electron microscopic analyses, it was found that the intercalation of zinc oxide nanoparticles expands the basal spacing of the host montmorillonite clay, and the crystallites of the nanohybrids are assembled to form a house-of-cards structure. From UV-vis spectroscopic investigation, it becomes certain that calcined nanohybrid contains two kinds of the zinc oxide species in the interlayer space of host lattice and in mesopores formed by the house-of-cards type stacking of the crystallites. Zn K-edge X-ray absorption near-edge structure/extended X-ray absorption fine structure analyses clearly demonstrate that guest species in the nanohybrids exist as nanocrystalline zinc oxides with wurzite-type structure.

Common clay and shale

USGS Publications Warehouse

Virta, R.L.

2011-01-01

The article discusses the latest developments in the global common clay and shale industry, particularly in the U.S. It claims that common clay and shale is mainly used in the manufacture of heavy clay products like brick, flue tile and sewer pipe. The main producing states in the U.S. include North Carolina, New York and Oklahoma. Among the firms that manufacture clay and shale-based products are Mid America Brick & Structural Clay Products LLC and Boral USA.

Mineralogical, chemical, and physical properties of the regolith overlying crystalline rocks, Fairfax County, Virginia: a preliminary report

USGS Publications Warehouse

Leo, Gerhard W.; Pavich, M.J.; Obermeier, Stephen F.

1977-01-01

Undisturbed cores of saprolite developed on crystalline rocks of the Piedmont Province in Fairfax County, Virginia have been obtained using a combination of Shelby tubes, Denison sampler, and modified diamond core-drilling. The principal purpose of the core study is to correlate variations in chemistry, mineralogy and texture with engineering properties throughout the weathering profile. Coring sites were chosen to obtain a maximum depth of weathering on diverse lithologies. The rocks investigated include pelitic schist, metagraywacke, granite, diabase and serpentinite. Four to twelve samples per core were selected, depending on thickness of 1) the weathering profile (from about 1 m in serpentinite to more than 30 m in pelitic schist) and on 2) megascopic changes in saprolite character for analysis of petrography, texture, clay mineralogy andd major element chemistry. Shear strength and compressibility were determined on corresponding segments of core. Standard penetration tests were performed adjacent to coring sites to evaluate engineering properties in situ. Geochemical changes of saprolite developed from each rock type follow predictable trends from fresh rock to soil profile, with relative Increases in Si, Ti, Al, Fe3+ and H20; variable K; and relative loss of Fe 2+, Mg, Ca, and Na. These variations are more pronounced in the weathering profiles over mafic and ultramafic rocks than metagraywacke. Clay minerals in granite, schist and metagraywacke saprolite are kaolinite, dioctahedral vermiculite, interlayered micavermiculite, and minor illite. Gibbsite is locally developed in near-surface samples of schist. Standard penetration test data for the upper 7 m of saprolite over schist and metagraywacke suggest alternations between stronger and weaker horizons than probably reflect variations in lithology including the presence of quartz lenses. Results for granite saprolite are most consistent but indicate lower strength. Shear strength increases fairly regularly

Comprehensive review of geosynthetic clay liner and compacted clay liner

NASA Astrophysics Data System (ADS)

Shankar, M. Uma; Muthukumar, M.

2017-11-01

Human activity inevitably produces waste materials that must be managed. Some waste can be reused. However many wastes that cannot be used beneficially must be disposed of ensuring environmental safety. One of the common methods of disposal is landfilling. The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Liner in a landfill is an important component which prevent leachate migration and prevent groundwater contamination. Earthen liners have been widely used to contain waste materials in landfill. Liners and covers for municipal and hazardous waste containment facilities are often constructed with the use of fine-grained, low plasticity soils. Because of low permeability geosynthetic clay liners and compacted clay liners are the main materials used in waste disposal landfills. This paper summaries the important geotechnical characteristics such as hydraulic conductivity, liquid limit and free swell index of geosynthetic clay liner and compacted clay liner based on research findings. This paper also compares geosynthetic clay liner and compacted clay liner based on certain criteria such as thickness, availability of materials, vulnerability to damage etc.

How does the composition affect the mechanical behaviour of simulated clay-rich fault gouges?

NASA Astrophysics Data System (ADS)

Bakker, Elisenda; Spiers, Christopher J.; Hangx, Suzanne J. T.

2014-05-01

CO2 capture and storage (CCS) in depleted oil and gas reservoirs is seen as one of the most promising large-scale CO2-mitigation strategies. Prediction of the effect of fluid-rock interaction on the mechanical integrity and sealing capacity of a reservoir-seal system, on timescales of the order of 1,000 or 10,000 years, is important to ensure the safety and containment of a reservoir in relation to long-term CO2 storage. However, most chemical reactions in rock/CO2/brine systems are slow, which means that long-term effects of fluids on rock composition, microstructure, mechanical properties and transport properties cannot be easily reproduced under laboratory conditions. One way to overcome this problem is to use simulated fault gouges in experiments, investigating a range of possible mineralogical compositions resulting from CO2-exposure. Previous studies have shown that the mechanical and transport properties of clay-rich fault gouges are significantly influenced by the mineralogy, particularly by the presence and relative amount of secondary phases, such as quartz and/or carbonate. In CCS settings, where dissolution and/or precipitation of carbonates may play an important role, the carbonate:clay ratio is expected to influence fault frictional behaviour. This is supported by the different behaviour of phyllosilicates, which generally show stable slip behaviour (aseismic), compared to carbonates, which have shown to become prone to unstable slip (potentially seismic) with increasing temperature. However, little is known about the mechanical and transport properties of carbonate/clay mixtures. We investigated the effect of the carbonate:clay ratio on fault friction, fault reactivation potential and slip stability, i.e. seismic vs. aseismic behaviour, as well as transmissivity evolution during and after fault reactivation. We used two types of starting material, derived from crushed Opalinus Claystone (Mont Terri, Switzerland): i) untreated samples consisting

Clay Minerals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller, Karl T.; Sanders, Rebecca L.; Washton, Nancy M.

2014-03-14

Clay minerals are important components of the environment and are involved or implicated in processes such as the uptake of pollutants and the release of nutrients and as potential platforms for a number of chemical reactions. Owing to their small particle sizes (typically, on the order of microns or smaller) and mixing with a variety of other minerals and soil components, advanced characterization methods are needed to study their structures, dynamics, and reactivities. In this article, we describe the use of solid-state NMR methods to characterize the structures and chemistries of clay minerals. Early one-pulse magic-angle spinning (MAS) NMR studiesmore » of 27Al and 29Si have now been enhanced and extended with new studies utilizing advanced methodologies (such as Multiple Quantum MAS) as well as studies of less-sensitive nuclei. In additional work, the issue of reactivity of clay minerals has been addressed, including studies of reactive surface area in the environment. Utilizations of NMR-sensitive nuclides within the clay minerals themselves, and in molecules that react with specific sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.« less

Carbonation of Clay Minerals Exposed to scCO2/Water at 200 degrees and 250 degrees C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugama, T.; Ecker, L.; Gill, S.

2010-11-01

To clarify the mechanisms of carbonation of clay minerals, such as bentonite, kaolinite, and soft clay, we exposed them to supercritical carbon dioxide (scCO2)/water at temperatures of 200 and 250 C and pressures of 1500 and 2000 psi for 72- and 107-hours. Bentonite, comprising three crystalline phases, montmorillonite (MMT), anorthoclase-type albite, and quartz was susceptible to reactions with ionic carbonic acid yielded by the interactions between scCO2 and water, particularly MMT and anorthoclase-type albite phases. For MMT, the cation-exchangeable ions, such as Na+ and Ca2+, present in its basal interplanar space, were replaced by proton, H+, from ionic carbonic acid;more » thereafter, the cations leaching from MMT directly reacted with CO32- as a counter ion of H+ to form carbonate compounds. Such in-situ carbonation process in basal space caused the shrinkage and breakage of the spacing structure within MMT. In contrast, the wet carbonation of anorthoclase-type albite, categorized as rock minerals, entailed the formation of three amorphous by-products, such as carbonates, kaolinite-like compounds, and silicon dioxide. Together, these two different carbonations caused the disintegration and corruption of bentonite. Kaolinite clay containing the amorphous carbonates and silicon dioxide was inert to wet carbonation. We noted only a gain in weight due to its water uptake, suggesting that kaolinite-like by-products generated by the wet carbonation of rock minerals might remain unchanged even during extended exposure. Soft clay consisting of two crystalline phases, dolomite and silicon dioxide, also was unaltered by wet carbonation, despite the uptake of water.« less

Mysterious Roving Rocks of Racetrack Playa

NASA Image and Video Library

2017-12-08

The trails have some curious features. Sometimes the clay gets pushed into a mound at the trail's end, as in this photo. Photo credit: NASA/GSFC/Cynthia Cheung To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Dust input in the formation of rock varnish from the Dry Valleys (Antarctica)

NASA Astrophysics Data System (ADS)

Zerboni, A.; Guglielmin, M.

2017-12-01

Rock varnish is a glossy, yellowish to dark brown coating that covers geomorphically stable, aerially exposed rock surfaces and landforms in warm and cold arid lands. In warm deserts, rock varnish consists of clay minerals, Mn-Fe oxides/hydroxides, and Si+alkalis dust; it occasionally containis sulphates, phosphates, and organic remains. In Antarctica, rock varnish developed on a variety of bedrocks and has been described being mostly formed of Si, Al, Fe, and sulphates, suggesting a double process in its formation, including biomineralization alternated to dust accretion. We investigated rock coatings developed on sandstones outcropping in the Dry Valleys of Antarctica and most of the samples highlithed an extremely complex varnish structure, alternating tihn layer of different chemical compostion. Optical microscope evidenced the occurrence of highly birefringent minerals, occasionally thinly laminated and consisitng of Si and Al-rich minerals (clays). These are interlayered by few micron-thick dark lenses and continous layers. The latter are well evident under the scanning electron microscope and chemical analysis confirmed that they consist of different kinds of sulphates; jarosite is the most represented species, but gypsum crystals were also found. Fe-rich hypocoatings and intergranula crusts were also detected, sometimes preserving the shape of the hyphae they have replaced. Moreover, small weathering pits on sandstone surface display the occurrence of an amorphous, dark Mn/Fe-rich rock varnish. The formation of rock varnish in the Dry Valleys is a complex process, which required the accretion of airborne dust of variable composition and subsequent recrystallization of some constituent, possibly promoted by microorganisms. In particualr, the formation of sulphates seems to preserve the memory of S-rich dust produced by volcanic eruptions. On the contrary, the formation of Mn-rich varnish should be in relation with the occurrence of higher environmental

Effects of rock mineralogy and pore structure on stress-dependent permeability of shale samples

PubMed Central

Al Ismail, Maytham I.; Zoback, Mark D.

2016-01-01

We conducted pulse-decay permeability experiments on Utica and Permian shale samples to investigate the effect of rock mineralogy and pore structure on the transport mechanisms using a non-adsorbing gas (argon). The mineralogy of the shale samples varied from clay rich to calcite rich (i.e. clay poor). Our permeability measurements and scanning electron microscopy images revealed that the permeability of the shale samples whose pores resided in the kerogen positively correlated with organic content. Our results showed that the absolute value of permeability was not affected by the mineral composition of the shale samples. Additionally, our results indicated that clay content played a significant role in the stress-dependent permeability. For clay-rich samples, we observed higher pore throat compressibility, which led to higher permeability reduction at increasing effective stress than with calcite-rich samples. Our findings highlight the importance of considering permeability to be stress dependent to achieve more accurate reservoir simulations especially for clay-rich shale reservoirs. This article is part of the themed issue ‘Energy and the subsurface’. PMID:27597792

Imprinted Clay Coil Vessels

ERIC Educational Resources Information Center

Lohr, Tresa Rae

2006-01-01

The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

Peculiarities of non-autoclaved lime wall materials production using clays

NASA Astrophysics Data System (ADS)

Volodchenko, A. A.; Lesovik, V. S.; Cherepanova, I. A.; Volodchenko, A. N.; Zagorodnjuk, L. H.; Elistratkin, M. Y.

2018-03-01

At present, the development and implementation of energy saving technologies for building materials production, which correspond to modern trends of «green» technologies, become ever more popular. One of the most widely spread wall materials today is a lime brick and stones. The primary raw goods used in production of such materials are quarziferous rocks. However, they have some disadvantages, including low strength index at the intermediate phase of their production, especially in case with a raw brick, which is an issue in the production of high-hollow goods due to low strength index of raw materials and the nonoptimal matrix structure. The conducted experiments confirmed the possibility to control structurization of building composites due to application of nonconventional argillous raw materials. Besides, the material and mineral composition of nonconventional clay rocks ensures the optimal microstructure thus providing for the production of efficient wall building materials via energy saving technology.

Nanoparticles migration in fractured rocks and affects on contaminant migration

NASA Astrophysics Data System (ADS)

Missana, Tiziana; Garcia-Gutierrez, Miguel; Alonso, Ursula

2014-05-01

In previous studies, the transport behavior of artificial (gold and latex) and natural (smectite clay) colloids, within a planar fracture in crystalline rock, was analyzed. In order to better understand the effects of colloid size, shape and surface charge on nanoparticle migration and especially on filtration processes on natural rock surfaces, different clay colloids and oxide nanoparticles were selected and their transport studied as a function of the residence time. In all the cases, (a fraction of) the nanoparticles travelled in the fracture as fast as or faster than water (with a retardation factor, Rf ≤ 1) and the observed Rf, was related to the Taylor dispersion coefficient, accounting for colloid size, water velocity and fracture width. However, under most of the cases, in contrast to the behavior of a conservative tracer, colloids recovery was much lower than 100 %. Differences in recovery between different nanoparticles, under similar residence times, were analyzed. In order to evaluate the possible consequences, on contaminant migration, of the presence of nanoparticles in the system, transport tests were carried out with both colloids and sorbing radionuclides. The overall capacity for colloids of enhancing radionuclide migration in crystalline rock fractures is discussed. Acknowledgments: The research leading to these results received funding from EU FP7/2007-2011 grant agreement Nº 295487 (BELBAR, Bentonite Erosion: effects on the Long term performance of the engineered Barrier and Radionuclide Transport) and by the Spanish Government under the project NANOBAG (CTM2011-2797).

Ultra-thin clay layers facilitate seismic slip in carbonate faults.

PubMed

Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Di Toro, Giulio; Spagnuolo, Elena; Zorzi, Federico

2017-04-06

Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms -1 ) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms -1 ), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

Evaluation of Five Sedimentary Rocks Other Than Salt for Geologic Repository Siting Purposes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Croff, A.G.; Lomenick, T.F.; Lowrie, R.S.

The US Department of Energy (DOE), in order to increase the diversity of rock types under consideration by the geologic disposal program, initiated the Sedimary ROck Program (SERP), whose immediate objectiv eis to evaluate five types of secimdnary rock - sandstone, chalk, carbonate rocks (limestone and dolostone), anhydrock, and shale - to determine the potential for siting a geologic repository. The evaluation of these five rock types, together with the ongoing salt studies, effectively results in the consideration of all types of relatively impermeable sedimentary rock for repository purposes. The results of this evaluation are expressed in terms of amore » ranking of the five rock types with respect to their potential to serve as a geologic repository host rock. This comparative evaluation was conducted on a non-site-specific basis, by use of generic information together with rock evaluation criteria (RECs) derived from the DOE siting guidelines for geologic repositories (CFR 1984). An information base relevant to rock evaluation using these RECs was developed in hydrology, geochemistry, rock characteristics (rock occurrences, thermal response, rock mechanics), natural resources, and rock dissolution. Evaluation against postclosure and preclosure RECs yielded a ranking of the five subject rocks with respect to their potential as repository host rocks. Shale was determined to be the most preferred of the five rock types, with sandstone a distant second, the carbonate rocks and anhydrock a more distant third, and chalk a relatively close fourth.« less

The Analysis of Weak Rock Using the Pressuremeter

NASA Astrophysics Data System (ADS)

Dafni, Jacob

The pressuremeter is a versatile in situ testing instrument capable of testing a large range of materials from very soft clay to weak rock. Due to limitations of other testing devices, the pressuremeter is one of the few instruments capable of capturing stiffness and strength properties of weak rock. However, data collected is only useful if the material tested is properly modeled and desirable material properties can be obtained. While constitutive models with various flows rules have been developed for pressuremeter analysis in soil, less research has been directed at model development for pressuremeter tests in weak rock. The result is pressuremeter data collected in rock is typically analyzed using models designed for soil. The aim of this study was to explore constitutive rock models for development into a pressuremeter framework. Three models were considered, with two of those three implemented for pressuremeter analysis. A Mohr-Coulomb model with a tensile cutoff developed by Haberfield (1987) and a Hoek-Brown model initiated by Yang et al (2011) and further developed by the author were implemented and calibrated against a data set of pressuremeter tests from 5 project test sites including a total of 115 pressuremeter tests in a number of different rock formations. Development of a multiscale damage model established by Kondo et al (2008) was explored. However, this model requires further development to be used for pressuremeter data analysis.

Rock magnetic and anisotropy of magnetic susceptibility(AMS) of earthquake affected soft sediments: Examples from Shillong and Latur (Deccan Trap), India.

NASA Astrophysics Data System (ADS)

Lakshmi, B. V., ,, Dr.; Gawali, Mr. Praveen B.; Deenadayalan, K., ,, Dr.; Ramesh, D. S., ,, Prof.

2017-04-01

Rock magnetic and anisotropy of magnetic susceptibility (AMS) of earthquake affected soft sediments: Examples from Shillong and Latur (Deccan Trap), India. B.V.Lakshmi, Praveen B.Gawali, K.Deenadayalan and D.S.Ramesh Indian Institute of Geomagnetism, plot 5, sector 18, Near Kalamboli Highway, New Panvel(W), Navi Mumbai 410218 Combined rock magnetism and anisotropy of magnetic susceptibility (AMS) studies on earthquake induced soft and non-soft sediments from Shillong and Latur, India have thrown up interesting results. The morphology of hysteresis loops, the pattern of isothermal remanent magnetization (IRM) acquisition, and temperature dependence of susceptibility indicate that titano-magnetite/magnetite is the main magnetic carrier in these sediments. We also analyzed the anisotropy of magnetic susceptibility (AMS) of liquefaction features within the seismically active Dauki fault, Shillong Plateau. We discovered that host sediments (non-liquefied), are characterized by an oblate AMS ellipsoid and liquefied sediment are characterized by a triaxial AMS ellipsoid, well grouped maximum susceptibility axis K1 (NNW-SSE trend). Field evidence and AMS analysis indicate that most of these features were emplaced by injection inferred to be due to seismically triggered fluidization. Anisotropy of magnetic susceptibility (AMS) of deformed and undeformed unconsolidated clay samples of Deccan Trap terrain from the 2000-year-old paleoearthquake site of Ther village, Maharashtra, India, was also studied. Such deposits are rare in the compact basaltic terrain because of which the results acquired are very important. The undeformed clay samples exhibit typical sedimentary fabric with an oblate AMS ellipsoid, whereas the deformed samples are tightly grouped in the inferred compression direction, probably effected by an earthquake, exhibiting prolate as well as oblate AMS ellipsoids. Rock magnetic and AMS methodology can help understand the behavior of different sediments to the

Wisconsin Glaciation of the Sierra Nevada (79,000-15,000 yr B.P.) as Recorded by Rock Flour in Sediments of Owens Lake, California

NASA Astrophysics Data System (ADS)

Bischoff, James L.; Cummins, Kathleen

2001-01-01

Chemical analyses of the clay-sized fractions of 564 continuous sediment samples (200-yr resolution) from composite core OL90/92 allow quantification of an abundance of glacial rock flour. Rock flour produced during glacier advances is represented by clay-sized plagioclase, K-feldspar, and biotite in homogeneous internal composition. The abundance of rock flour is deemed proportional to the intensity of glacies advances. Age control for the composite section is provided by combining previously published radiocarbon dates on organics, U/Th dates on ostracode shells, and U/Th dates on saline minerals from nearby Searles Lake correlated to OL92 by pollen. The rock flour record displays three levels of variability: (1) a dominant one of about 20,000 yr related to summer insolation and precipitation; (2) an intermediate one of 3000-5000 yr, perhaps related to North Atlantic Heinrich events; and (3) a minor one of 1000-2000 yr, perhaps related to North Atlantic thermohaline-driven air-temperature variation.

Wisconsin Glaciation of the Sierra Nevada (79,000-15,000 yr B.P.) as recorded by rock flour in sediments of Owens Lake, California

USGS Publications Warehouse

Bischoff, J.L.; Cummins, K.

2001-01-01

Chemical analyses of the clay-sized fractions of 564 continuous sediment samples (200-yr resolution) from composite core OL90/92 allow quantification of an abundance of glacial rock flour. Rock flour produced during glacier advances is represented by clay-sized plagioclase, K-feldspar, and biotite in homogeneous internal composition. The abundance of rock flour is deemed proportional to the intensity of glacies advances. Age control for the composite section is provided by combining previously published radiocarbon dates on organics, U/Th dates on ostracode shells, and U/Th dates on saline minerals from nearby Searles Lake correlated to OL92 by pollen. The rock flour record displays three levels of variability: (1) a dominant one of about 20,000 yr related to summer insolation and precipitation; (2) an intermediate one of 3000-5000 yr, perhaps related to North Atlantic Heinrich events; and (3) a minor one of 1000-2000 yr, perhaps related to North Atlantic thermohaline-driven air-temperature variation. ?? 2001 University of Washington.

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

NASA Astrophysics Data System (ADS)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Magmatic Enclaves in Granitic Rocks: Paragons or Parasites?

NASA Astrophysics Data System (ADS)

Clemens, John; Stevens, Gary; Elburg, Marlina

2017-04-01

Granitic rocks form the fundamental building blocks of Earth's continents and provide us with a wide range of resources, so their formation is worth trying to understand. Fine-grained, igneous-textured microgranular enclaves of tonalitic to monzogranitic composition (ME) are common in granitic rocks and their origins have been hotly debated, with some workers suggesting that ME are not igneous. These ME have been studied intensively enough that we are now certain that they are of igneous origin - globules of mingled and quenched magma. Although a mantle connection is evident in many cases, their ultimate origin (including where in the lithosphere they originate) is still debated. This contribution explores the systematics of chemical variation in ME and their host granites, with the aim of uncovering any systematics in their behaviour and modelling the processes that have led to the variations that we measure, comparing host-rock series to their respective ME series. As always, the hope is that the study of ME may lead to improved understanding and modelling of the processes that are responsible for the formation of the host granitic magmas. Using variations between the molecular quantities Ti and M (Fe+Mn+Mg), we demonstrate that the petrogenetic processes that operated within a diverse group of S- and I-type granitic host magmas and their ME suites are dissimilar. Variations within the granitic series result from a variety of what might be called 'orderly' processes, resulting in linear or curvilinear trends in chemical variation diagrams. In contrast, processes that affected the ME series commonly resulted in scattered, chaotic variations. Even in cases in which an ME series displays more orderly variation, it can be shown that the hypothesis of simple mixing between a parent enclave magma and its host granitic magma, to produce the overall variations, cannot be supported. ME magmas had vastly smaller volumes compared with their host granitic magmas. Thus, they

Clay-mineraloid weathering products in Antarctic meteorites

NASA Technical Reports Server (NTRS)

Gooding, James L.

1986-01-01

The production of clay mineraloids (CMs) in the weathering of stony meteorites recovered in the Allan Hills and Elephant Moraine areas of Antarctica is investigated, applying electron microbeam analysis, pyrolysis/mass spectroscopy, X-ray diffractometry, and differential scanning calorimetry to whole-rock chips from two eucrites, two diogenites, and an H5 chondrite. The data are presented in tables, graphs, and photomicrographs and characterized in detail. Massive to incipient-vermicular CM formations with smectitelike or micalike compositions and indications of poor crystallization are observed and attributed to hydrocryogenic diagenesis (with little or no liquid water) on time scales of 10-1000 kyr. The need to take the compositional effects of weathering into account before attempting to reconstruct the preterrestrial histories of meteorites is stressed.

Clay Mineralogy of AN Alluvial Aquifer in a Mountainous, Semiarid Terrain, AN Example from Rifle, Colorado

NASA Astrophysics Data System (ADS)

Elliott, W. C.; Lim, D.; Zaunbrecher, L. K.; Pickering, R. A.; Williams, K. H.; Navarre-Sitchler, A.; Long, P. E.; Noel, V.; Bargar, J.; Qafoku, N. P.

2015-12-01

Alluvial sediments deposited along the Colorado River corridor in the semi-arid regions of central to western Colorado can be important hosts for legacy contamination including U, V, As and Se. These alluvial sediments host aquifers which are thought to provide important "hot spots" and "hot moments" for microbiological activity controlling organic carbon processing and fluxes in the subsurface. Relatively little is known about the clay mineralogy of these alluvial aquifers and the parent alluvial sediments in spite of the fact that they commonly include lenses of silt-clay materials. These lenses are typically more reduced than coarser grained materials, but zones of reduced and more oxidized materials are present in these alluvial aquifer sediments. The clay mineralogy of the non-reduced parent alluvial sediments of the alluvial aquifer located in Rifle, CO (USA) is composed of chlorite, smectite, illite, kaolinite and quartz. The clay mineralogy of non-reduced fine-grained materials at Rifle are composed of the same suite of minerals found in the sediments plus a vermiculite-smectite intergrade that occurs near the bottom of the aquifer near the top of the Wasatch Formation. The clay mineral assemblages of the system reflect the mineralogically immature character of the source sediments. These assemblages are consistent with sediments and soils that formed in a moderately low rainfall climate and suggestive of minimal transport of the alluvial sediments from their source areas. Chlorite, smectite, smectite-vermiculite intergrade, and illite are the likely phases involved in the sorption of organic carbon and related microbial redox transformations of metals in these sediments. Both the occurrence and abundance of chlorite, smectite-vermiculite, illite and smectite can therefore exert an important control on the contaminant fluxes and are important determinants of biogeofacies in mountainous, semiarid terrains.

Clay: The Forgotten Art.

ERIC Educational Resources Information Center

Martin, Doris Marie

1995-01-01

Discusses the tactile and kinesthetic areas of learning children experience when using clay. Includes practical tips for using and storing clay for preschool use and notes the differences between potters' clay and play dough. (HTH)

Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites

PubMed Central

Zope, Indraneel S.; Yu, Zhong-Zhen

2017-01-01

Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition. PMID:28800095

Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

PubMed

Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

2017-08-11

Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

Genetic aspects of barite mineralization related to rocks of the teschenite association in the Silesian Unit, Outer Western Carpathians, Czech Republic

NASA Astrophysics Data System (ADS)

Jirásek, Jakub; Dolníček, Zdeněk; Matýsek, Dalibor; Urubek, Tomáš

2017-04-01

Barite is a relatively uncommon phase in vein and amygdule mineralizations hosted by igneous rocks of the teschenite association in the Silesian Unit (Western Carpathians). In macroscopically observable sizes, it has been reported from 10 sites situated only in the Czech part of the Silesian Unit. Microscopic barite produced by the hydrothermal alteration of rock matrix and also by the supergene processes is more abundant. We examined four samples of barite by mineralogical and geochemical methods. Electron microprobe analyses proved pure barites with up to 0.038 apfu Sr and without remarkable internal zonation. Fluid inclusion and sulphur isotope data suggests that multiple sources of fluid components have been involved during barite crystallization. Barite contains primary and secondary aqueous all-liquid (L) or less frequent two-phase (L+V) aqueous fluid inclusions with variable salinity (0.4-2.9 wt. % NaCl eq.) and homogenization temperatures between 77 and 152 °C. The higher-salinity fluid endmember was probably Cretaceous seawater and the lower-salinity one was probably diagenetic water derived from surrounding flysch sediments during compaction and thermal alteration of clay minerals. The δ34S values of barite samples range between -1.0 ‰ and +16.4 ‰ CDT suggesting participation of two sources of sulphate, one with a near-zero δ34S values probably derived from wall rocks and another with high δ34S values being most probably sulphate from the Cretaceous seawater. All results underline the role of externally derived fluids during post-magmatic alteration of bodies of rock of the teschenite association.

Mineral and energy resources of the BLM Roswell Resource Area, east-central New Mexico

USGS Publications Warehouse

Bartsch-Winkler, Susan B.

1992-01-01

The sedimentary formations of the Roswell Resource Area have significant mineral and energy resources. Some of the pre-Pennsylvanian sequences in the Northwestern Shelf of the Permian Basin are oil and gas reservoirs, and Pennsylvanian rocks in Tucumcari basin are reservoirs of oil and gas as well as source rocks for oil and gas in Triassic rocks. Pre-Permian rocks also contain minor deposits of uranium and vanadium, limestone, and associated gases. Hydrocarbon reservoirs in Permian rocks include associated gases such as carbon dioxide, helium, and nitrogen. Permian rocks are mineralized adjacent to the Lincoln County porphyry belt, and include deposits of copper, uranium, manganese, iron, polymetallic veins, and Mississippi-valley-type (MVT) lead-zinc. Industrial minerals in Permian rocks include fluorite, barite, potash, halite, polyhalite, gypsum, anhydrite, sulfur, limestone, dolomite, brine deposits (iodine and bromine), aggregate (sand), and dimension stone. Doubly terminated quartz crystals, called "Pecos diamonds" and collected as mineral specimens, occur in Permian rocks along the Pecos River. Mesozoic sedimentary rocks are hosts for copper, uranium, and small quantities of gold-silver-tellurium veins, as well as significant deposits of oil and gas, COa, asphalt, coal, and dimension stone. Mesozoic rocks contain limited amounts of limestone, gypsum, petrified wood, dinosaur remains, and clays. Tertiary rocks host ore deposits commonly associated with intrusive rocks, including platinum group elements, iron skarns, manganese, uranium and vanadium, molybdenum, polymetallic vein deposits, gold-silver- tellurium veins, and thorium-rare earth veins. Museum-quality quartz crystals in Lincoln County were formed in association with intrusive rocks in the Lincoln County porphyry belt. Industrial minerals in Tertiary rocks include fluorite, vein- and bedded-barite, caliche, limestone, and aggregate. Tertiary and Quaternary sediments host important placer deposits of

Experimental thermomechanical damage as first approach to understand the petrophysical behavior of the granitic host-rocks from an active fractured-geothermal system (Liquiñe, Chile - 39º S)

NASA Astrophysics Data System (ADS)

Molina Piernas, E.; Sepúlveda, J.; Arancibia, G.; Roquer, T.; Morata, D.; Bracke, R.; Vázquez, P.

2017-12-01

Chile's location along an active subduction zone has endowed it with a high geothermal potential. However, a better understanding of the thermomechanical and fluid transport properties of rocks is required to assess the potential of geothermal systems and thereby enhance the possibilities for their use. We have focused in the area surrounding Liquiñe, in the Southern Andean Volcanic Zone (Chile, 39º S). This area hosts several recent thermal manifestations, predominantly hot springs, and it is affected by the Liquiñe-Ofqui Fault Zone (LOFZ), which controls the position of the modern volcanic arc in southern Chile and cuts the Patagonian batholith. We have carried out experimental analyzes in order to understand this geothermal system and the influence of the thermomechanical features over the granitic host-rocks (low-porous crystalline rocks). To do this, physical properties such as capillary water absorption coefficient, Vp-wave velocity and compressive resistance were evaluated before and after heating rock samples at 150 ºC and 210 ºC (at ambient pressure) in an oven at a heating rate of 6 °C/min and maintaining the maximum temperature for 4 hours. The cooling rate was less than 2 °C/min to avoid shrinkage phenomena. The results show that the damage by heat was greater at 210 ºC than 150 ºC, likely due to an increased capillary coefficient ( 30% and 25%). On the contrary, Vpvelocity ( -19% and -13%) and compressive resistance ( -27% in both cases) decreased, with respect to unheated samples. Consequently, we can infer an inherent effect on the later fracture process due to the thermal stress when this granitic body was at depth. After that, and considering the local and regional strain-stress state, both factors have facilitated the fluid flow, increasing the permeability of this granitic host-rock allowing the presence of hot-springs. Future work will be to acquire complementary petrophysical parameters, such as porosity, permeability, thermal

Ball clay

USGS Publications Warehouse

Virta, R.L.

2012-01-01

Four companies — H.C. Spinks Clay Co., Inc., Imerys Group, Old Hickory Clay Co., and Unimin Corp. — mined ball clay in four states in 2011. Production, on the basis of preliminary data, was 940 kt (1.04 million st) with an estimated value of $44.2 million. This is a 3-percent increase in tonnage from 912 kt (1.01 million st) with a value of $41.3 million that was produced in 2010. Tennessee was the leading producing state with 63 percent of domestic production, followed by Texas, Mississippi and Kentucky. About 69 percent of production was airfloat, 20 percent was crude and 11 percent was water-slurried.

Magnetic resonance imaging of clays: swelling, sedimentation, dissolution

NASA Astrophysics Data System (ADS)

Dvinskikh, Sergey; Furo, Istvan

2010-05-01

While most magnetic resonance imaging (MRI) applications concern medical research, there is a rapidly increasing number of MRI studies in the field of environmental science and technology. In this presentation, MRI will be introduced from the latter perspective. While many processes in these areas are similar to those addressed in medical applications of MRI, parameters and experimental implementations are often quite different and, in many respects, far more demanding. This hinders direct transfer of existing methods developed for biomedical research, especially when facing the challenging task of obtaining spatially resolved quantitative information. In MRI investigation of soils, clays, and rocks, mainly water signal is detected, similarly to MRI of biological and medical samples. However, a strong variation of water mobility and a wide spread of water spin relaxation properties in these materials make it difficult to use standard MRI approaches. Other significant limitations can be identified as following: T2 relaxation and probe dead time effects; molecular diffusion artifacts; varying dielectric losses and induced currents in conductive samples; limited dynamic range; blurring artifacts accompanying drive for increasing sensitivity and/or imaging speed. Despite these limitations, by combining MRI techniques developed for solid and liquid states and using independent information on relaxation properties of water, interacting with the material of interest, true images of distributions of both water, material and molecular properties in a wide range of concentrations can be obtained. Examples of MRI application will be given in the areas of soil and mineral research where understanding water transport and erosion processes is one of the key challenges. Efforts in developing and adapting MRI approaches to study these kinds of systems will be outlined as well. Extensive studies of clay/water interaction have been carried out in order to provide a quantitative

Exploring biotic vs. abiotic controls on syngenetic carbonate and clay mineral precipitation

NASA Astrophysics Data System (ADS)

Nascimento, Gabriela S.; McKenzie, Judith A.; Martinez Ruiz, Francisca; Bontognali, Tomaso R. R.; Vasconcelos, Crisogono

2016-04-01

A possible syngenetic relationship between carbonate and clay mineral precipitation has been reported for sedimentary rocks deposited in both lacustrine and marine sedimentary environments throughout the geological record. In particular, the mineral dolomite is often found associated with Mg-rich clays, such as stevensite. It is notable that this carbonate/clay association has been recorded in numerous samples taken from modern dolomite precipitating environments; for example, the Coorong lakes, South Australia, coastal sabkhas, Abu Dhabi, UAE and coastal hypersaline lagoons (Lagoa Vermelha and Brejo do Espinho) east of Rio de Janeiro, Brazil. An HRTEM study of samples from these three locations indicates a possible physical/chemical association between the Ca-dolomite and Mg-rich clays, demonstrating a probable co-precipitation. To test this hypothesis, we have conducted a series of biotic and abiotic laboratory experiments. If this syngenesis actually occurs in nature, what, if any, are the biogeochemical processes controlling these precipitation reactions? Our experiments were designed to determine the extent of the biotic versus abiotic component influencing the mineral precipitation and, in the case of a biotic influence, to understand the mechanism through which microorganisms might mediate the formation of clay minerals. The experiments were carried out in the Geomicrobiology Laboratory of ETH Zürich using cultures of living microbes and artificial organic compounds that simulate functional groups present in natural biofilms formed under both aerobic and anaerobic conditions. In addition, pure inorganic experiments were designed to understand possible physico-chemical conditions for diagenetic processes that could induce dissolution of Mg-carbonates and precipitation of Mg-rich clays. Our results show a remarkable biotic influence during the formation of clay minerals. Specifically, extracellular polymeric substances (EPS), released by microbes in their

Modelling of clay diagenesis using a combined approach of crystalchemistry and thermochemistry: a case study in the smectite illitization.

NASA Astrophysics Data System (ADS)

Geloni, Claudio; Previde Massara, Elisabetta; Di Paola, Eleonora; Ortenzi, Andrea; Gherardi, Fabrizio; Blanc, Philippe

2017-04-01

Diagenetic transformations occurring in clayey and arenaceous sediments is investigated in a number of hydrocarbon reservoirs with an integrated approach that combines mineralogical analysis, crystalchemistry, estimation of thermochemical parameters of clay minerals, and geochemical modelling. Because of the extremely variable crystalchemistry of clays, especially in the smectite - illite compositional range, the estimation of thermochemical parameters of site-specific clay-rich rocks is crucial to investigate water-rock equilibria and to predict mineralogical evolutionary patterns at the clay-sandstone interface. The task of estimating the thermochemical properties of clay minerals and predicting diagenetic reactions in natural reservoirs is accomplished through the implementation of an informatized, procedure (IP) that consists of: (i) laboratory analysis of smectite, illite and mixed layers (I/S) for the determination of their textural characteristics and chemical composition; (ii) estimation of the thermodynamic and structural parameters (enthalpy, entropy, and free energy of formation, thermal capacity, molar volume, molar weight) with a MS Excel tool (XLS) specifically developed at the French Bureau of Geological and Mining Researches (BRGM); (iii) usage of the SUPCRT (Johnson et al., 1992) software package (thereinafter, SSP) to derive log K values to be incorporated in thermodynamic databases of the standard geochemical codes; (iv) check of the consistency of the stability domains calculated with these log K values with relevant predominance diagrams; (v) final application of geochemical and reactive transport models to investigate the reactive mechanisms under different thermal conditions (40-150°C). All the simulations consider pore waters having roughly the same chemical composition of reservoir pore waters, and are performed with The Geochemist Workbench (Bethke and Yeakel, 2015), PHREEQC (Parkhurst, 1999) and TOUGHREACT (Xu, 2006). The overall

Implications of meso- to micro-scale deformation for fault sealing capacity: Insights from the Lenghu5 fold-and-thrust belt, Qaidam Basin, NE Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xie, Liujuan; Pei, Yangwen; Li, Anren; Wu, Kongyou

2018-06-01

As faults can be barriers to or conduits for fluid flow, it is critical to understand fault seal processes and their effects on the sealing capacity of a fault zone. Apart from the stratigraphic juxtaposition between the hanging wall and footwall, the development of fault rocks is of great importance in changing the sealing capacity of a fault zone. Therefore, field-based structural analysis has been employed to identify the meso-scale and micro-scale deformation features and to understand their effects on modifying the porosity of fault rocks. In this study, the Lenghu5 fold-and-thrust belt (northern Qaidam Basin, NE Tibetan Plateau), with well-exposed outcrops, was selected as an example for meso-scale outcrop mapping and SEM (Scanning Electron Microscope) micro-scale structural analysis. The detailed outcrop maps enabled us to link the samples with meso-scale fault architecture. The representative rock samples, collected in both the fault zones and the undeformed hanging walls/footwalls, were studied by SEM micro-structural analysis to identify the deformation features at the micro-scale and evaluate their influences on the fluid flow properties of the fault rocks. Based on the multi-scale structural analyses, the deformation mechanisms accounting for porosity reduction in the fault rocks have been identified, which are clay smearing, phyllosilicate-framework networking and cataclasis. The sealing capacity is highly dependent on the clay content: high concentrations of clay minerals in fault rocks are likely to form continuous clay smears or micro- clay smears between framework silicates, which can significantly decrease the porosity of the fault rocks. However, there is no direct link between the fault rocks and host rocks. Similar stratigraphic juxtapositions can generate fault rocks with very different magnitudes of porosity reduction. The resultant fault rocks can only be predicted only when the fault throw is smaller than the thickness of a faulted bed, in

Aqueous Alteration of Endeavour Crater Rim Apron Rocks

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Ming, Douglas W.; Gellert, Ralf; Clark, Benton C.; Morris, Richard V.; Yen, Albert S.; Arvidson, Raymond E.; Crumpler, Larry S.; Farrand, William H.; Grant, John A.;

Aqueous Alteration of Endeavour Crater Rim Apron Rocks

NASA Astrophysics Data System (ADS)

Ming, D. W.; Mittlefehldt, D. W.; Gellert, R.; Clark, B. C.; Morris, R. V.; Yen, A. S.; Arvidson, R. E.; Crumpler, L. S.; Farrand, W. H.; Grant, J. A., III; Jolliff, B. L.; Parker, T. J.; Peretyazhko, T.

2014-12-01

Mars Exploration Rover Opportunity is exploring Noachian age rocks of the rim of 22 km diameter Endeavour crater. Overlying the pre-impact lithologies and rim breccias is a thin apron of fine-grained sediments, the Grasberg fm, forming annuli on the lower slopes of rim segments. Hesperian Burns fm sandstones overly the Grasberg fm. Grasberg rocks have major element compositions that are distinct from Burns fm sandstones, especially when comparing interior compositions exposed by the Rock Abrasion Tool. Grasberg rocks are also different from Endeavour rim breccias, but have general compositional similarities to them. Grasberg sediments are plausibly fine-grained materials derived from the impact breccias. Veins of CaSO4 transect Grasberg fm rocks demonstrating post-formation aqueous alteration. Minor/trace elements show variations consistent with mobilization by aqueous fluids. Grasberg fm rocks have low Mn and high Fe/Mn ratios compared to the other lithologies. Manganese likely was mobilized and removed from the Grasberg host rock by redox reactions. We posit that Fe2+ from acidic solutions associated with formation of the Burns sulfate-rich sandstones acted as an electron donor to reduce more oxidized Mn to Mn2+. The Fe contents of Grasberg rocks are slightly higher than in other rocks suggesting precipitation of Fe phases in Grasberg materials. Pancam spectra show that Grasberg rocks have a higher fraction of ferric oxide minerals than other Endeavour rim rocks. Solutions transported Mn2+ into the Endeavour rim materials and oxidized and/or precipitated it in them. Grasberg has higher contents of the mobile elements K, Zn, Cl, and Br compared to the rim materials. Similar enrichments of mobile elements were measured by the Spirit APXS on West Spur and around Home Plate in Gusev crater. Enhancements in these elements are attributed to interactions of hydrothermal acidic fluids with the host rocks. Interactions of fluids with the Grasberg fm postdate the genesis

Mysterious Roving Rocks of Racetrack Playa

NASA Image and Video Library

2017-12-08

Intern Kyle Yawn marked the boundaries of this trail by placing pushpins into cracks in the clay. Now, he photographs the trail to document it. Photo credit: NASA/GSFC/Maggie McAdam To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Common clay and shale

USGS Publications Warehouse

Virta, R.L.

2000-01-01

Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

NASA Technical Reports Server (NTRS)

Miller, Sandi G (Inventor)

2013-01-01

A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

Relation between Fabric Anisotropy of Host-Rock vis-à-vis Far-Field Stress, and the Emplacement Of Pegmatite Dikes - an example from the Dharwar Craton (South India)

NASA Astrophysics Data System (ADS)

Bhatt, S.; Rana, V.; Mamtani, M. A.

2017-12-01

Dikes are known to control magma transport within the lithosphere. They (dikes) usually form by the fracturing of host rock and propagate orthogonal to the minimum principal stress direction and/or may follow the pre-existing anisotropy depending on the magnitude of fluid pressure and the tensile strength of the host rock. Pegmatite veins/dikes are often associated with hydraulic fracturing and high magmatic fluid pressure, which is attributed to volatile rich hydrous melt. The Koppal Pluton (KP) is a syenite body that lies to the East of the Chitradurga Shear Zone, which separates the Dharwar Craton into East and West Dharwar Craton. The KP is visually isotropic and profusely permeated by pegmatite dikes. Orientation data of the pegmatite dikes (n=357) were collected for geometric and paleostress analysis. The orientation of anisotropy with respect to the maximum principal stress and fluid pressure dictates whether a new fracture will form or a pre-existing anisotropy will be reactivated/dilated. To understand the relationship between the pre-existing anisotropy and orientation of pegmatite dikes, anisotropy of magnetic susceptibility (AMS) analysis was performed on the samples of KP. AMS analysis reveals NNE-SSW oriented magnetic fabric ascribed to regional D3 deformational event (NW-SE compression). Mean orientation of the magnetic fabric (NNE-SSW) is oblique to the mean orientation of the pegmatite dikes (NNW-SSE). It is envisaged that pegmatite dikes emplaced syntectonically as mode-I crack during regional D3 deformation event (pure shear dominated transpression) and developed oblique to the magnetic fabric of the pluton. The present study leads to a better understanding about the influence and interaction of principle stress, magmatic fluid pressure, and host-rock anisotropy on the ascent and emplacement of pegmatite dikes that intrude the visually isotropic KP. Acknowledgments: SB acknowledges INSPIRE Fellowship Programme (Award no: IF131138) of DST (New

Clay nanoparticles for regenerative medicine and biomaterial design: A review of clay bioactivity.

PubMed

Mousa, Mohamed; Evans, Nicholas D; Oreffo, Richard O C; Dawson, Jonathan I

2018-03-01

Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

Feasibility of Plasma Treated Clay in Clay/Polymer Nanocomposites Powders for use Laser Sintering (LS)

NASA Astrophysics Data System (ADS)

Almansoori, Alaa; Seabright, Ryan; Majewski, C.; Rodenburg, C.

2017-05-01

The addition of small quantities of nano-clay to nylon is known to improve mechanical properties of the resulting nano-composite. However, achieving a uniform dispersion and distribution of the clay within the base polymer can prove difficult. A demonstration of the fabrication and characterization of plasma-treated organoclay/Nylon12 nanocomposite was carried out with the aim of achieving better dispersion of clay platelets on the Nylon12 particle surface. Air-plasma etching was used to enhance the compatibility between clays and polymers to ensure a uniform clay dispersion in composite powders. Downward heat sintering (DHS) in a hot press is used to process neat and composite powders into tensile and XRD specimens. Morphological studies using Low Voltage Scanning Electron Microscopy (LV-SEM) were undertaken to characterize the fracture surfaces and clay dispersion in powders and final composite specimens. Thermogravimetric analysis (TGA) testing performed that the etched clay (EC) is more stable than the nonetched clay (NEC), even at higher temperatures. The influence of the clay ratio and the clay plasma treatment process on the mechanical properties of the nanocomposites was studied by tensile testing. The composite fabricated from (3% EC/N12) powder showed ~19 % improvement in elastic modulus while the composite made from (3% NEC/N12) powder was improved by only 14%). Most notably however is that the variation between tests is strongly reduced when etch clay is used in the composite. We attribute this to a more uniform distribution and better dispersion of the plasma treated clay within polymer powders and ultimately the composite.

Cyclic deformations in the Opalinus clay: a laboratory experiment

NASA Astrophysics Data System (ADS)

Huber, Emanuel; Huggenberger, Peter; Möri, Andreas; Meier, Edi

2015-04-01

The influence of tunnel climate on deformation cycles of joint openings and closings is often observed immediately after excavation. At the EZ-B niche in the Mt. Terri rock laboratory (Switzerland), a cyclic deformation of the shaly Opalinus clay has been monitored for several years. The deformation cycles of the joints parallel to the clay bedding planes correlate with seasonal variations in relative humidity of the air in the niche. In winter, when the relative humidity is the lowest (down to 65%), the joints open as the clay volume decreases, whereas they tend to close in the summer when the relative humidity reaches up to 100%. Furthermore, in situ measurements have shown the trend of an increasingly smaller aperture of joints with time. A laboratory experiment was carried out to reproduce the observed cyclic deformation in a climate chamber using a core sample of Opalinus clay. The main goal of the experiment was to investigate the influence of the relative humidity on the deformation of the Opalinus clay while excluding the in situ effects (e.g. confining stress). The core sample of Opalinus clay was put into a closed ended PVC tube and the space between the sample and the tube was filled with resin. Then, the sample (size: 28 cm × 14 cm × 6.5 cm) was cut in half lengthways and the open end was cut, so that the half-core sample could move in one direction. The mounted sample was exposed to wetting and drying cycles in a climate chamber. Air temperature, air humidity and sample weight were continuously recorded. Photographs taken at regular time intervals by a webcam allowed the formation/deformation of cracks on the surface of the sample to be monitored. A crackmeter consisting of a double-plate capacitor attached to the core sample was developed to measure the dynamics of the crack opening and closing. Preliminary results show that: - Deformation movements during different climate cycles can be visualized with the webcam - The crackmeter signal gives a

Clay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)

NASA Astrophysics Data System (ADS)

El Ouahabi, Meriam; Hubert-Ferrari, Aurelia; Lamair, Laura; Hage, Sophie

2017-04-01

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite

Nectonema zealandica n. sp. (Nematomorpha: Nectonematoidea) parasitising the purple rock crab Hemigrapsus edwardsi (Brachyura: Decapoda) in New Zealand, with notes on the prevalence of infection and host defence reactions.

PubMed

Poinar, G; Brockerhoff, A M

2001-10-01

A new species of marine hairworm, Nectonema zealandica (Nematomorpha: Nectonematoidea), is described from the purple rock crab Hemigrapsus edwardsi Hilgendorf from the South Island, New Zealand. This is the first record of Nectonema in the South Pacific Ocean and the southernmost locality for the genus. The description is based on juveniles and pre-adults taken from crabs. The new species is characterised by its stomal structure, presence of four cephalic papillae, mesenchyme arranged in eight lobes in pre-adults, insertion of muscle layer increasing body diameter at the septum and translucent anterior chamber. Data on the prevalence of infection over a three-year period, rates of parasitism in relation to host sex and size, and host defence reactions are presented. A list of all reported hosts of nectonematids is included.

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

NASA Astrophysics Data System (ADS)

Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

2017-06-01

In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Further studies on the problems of geomagnetic field intensity determination from archaeological baked clay materials

NASA Astrophysics Data System (ADS)

Kostadinova-Avramova, M.; Kovacheva, M.

2015-10-01

Archaeological baked clay remains provide valuable information about the geomagnetic field in historical past, but determination of the geomagnetic field characteristics, especially intensity, is often a difficult task. This study was undertaken to elucidate the reasons for unsuccessful intensity determination experiments obtained from two different Bulgarian archaeological sites (Nessebar - Early Byzantine period and Malenovo - Early Iron Age). With this aim, artificial clay samples were formed in the laboratory and investigated. The clay used for the artificial samples preparation differs according to its initial state. Nessebar clay was baked in the antiquity, but Malenovo clay was raw, taken from the clay deposit near the site. The obtained artificial samples were repeatedly heated eight times in known magnetic field to 700 °C. X-ray diffraction analyses and rock-magnetic experiments were performed to obtain information about the mineralogical content and magnetic properties of the initial and laboratory heated clays. Two different protocols were applied for the intensity determination-Coe version of Thellier and Thellier method and multispecimen parallel differential pTRM protocol. Various combinations of laboratory fields and mutual positions of the directions of laboratory field and carried thermoremanence were used in the performed Coe experiment. The obtained results indicate that the failure of this experiment is probably related to unfavourable grain sizes of the prevailing magnetic carriers combined with the chosen experimental conditions. The multispecimen parallel differential pTRM protocol in its original form gives excellent results for the artificial samples, but failed for the real samples (samples coming from previously studied kilns of Nessebar and Malenovo sites). Obviously the strong dependence of this method on the homogeneity of the used subsamples hinders its implementation in its original form for archaeomaterials. The latter are often

CO 2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rother, Gernot; Ilton, Eugene S.; Wallacher, Dirk

2013-01-02

Geologic storage of CO 2 requires that the caprock sealing the storage rock is highly impermeable to CO 2. Swelling clays, which are important components of caprocks, may interact with CO 2 leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO 2 with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of ≈0.15 g/cm 3, followed by an approximately linear decrease of excess sorption to zero and negativemore » values with increasing CO 2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO 2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO 2 in the clay pores is relatively stable over a wide range of CO 2 pressures at a given temperature, indicating the formation of a clay-CO 2 phase. Finally, at the excess sorption maximum, increasing CO 2 sorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak temperature dependence.« less

Acid rock drainage passive remediation using alkaline clay and impacts of vegetation and saturated sand barrier

NASA Astrophysics Data System (ADS)

Plaza, F.; Wen, Y.; Liang, X.

2017-12-01

Acid rock drainage (ARD) caused by abundance of coal refuse (CR) deposits in mining regions requires adequate treatment to prevent serious water pollution due to its acidity and high concentrations of sulfate and metals/metalloids. Over the past decades, various approaches have been explored and developed to remediate ARD. This study uses laboratory experiments to investigate the effectiveness and impacts of ARD passive remediation using alkaline clay (AC), a by-product of the aluminum refining process. Twelve column kinetic leaching experiments were set up with CR/AC mixing ratios ranging from 1%AC to 10%AC. Samples were collected from these columns to measure the pH, sulfate, metals/metalloids, acidity and alkalinity. Additional tests of XRD and acid base accounting were also conducted to better characterize the mineral phase in terms of the alkalinity and acidity potential. Based on the leachate measurement results, these columns were further classified into two groups of neutral/near neutral pH and acidic pH for further analysis. In addition, impacts of the vegetation and saturated sand layer on the remediation effectiveness were explored. The results of our long-term (more than three years in some cases) laboratory experiments show that AC is an effective ARD remediation material for the neutralization of leachate pH and immobilization of sulfate and metals such as Fe, Mn, Cu, Zn, Ni, Pb, Cd, Co. The CR/AC mixing ratios higher than 3%AC are found to be effective, with 10% close to optimal. Moreover, the results demonstrate the benefits of using vegetation and a saturated sand barrier. Vegetation acted as a phytoaccumulation/phytoextraction agent, causing an additional immobilization of metals. The saturated sand barrier blocked the oxygen and water diffusion downwards, leading to a reduction of the pyrite oxidation rate. Finally, the proposed remediation approach shows that the acidity consumption will likely occur before all the alkalinity is exhausted

Permeability of volcanic rocks to gas and water

NASA Astrophysics Data System (ADS)

Heap, M. J.; Reuschlé, T.; Farquharson, J. I.; Baud, P.

2018-04-01

The phase (gas or liquid) of the fluids within a porous volcanic system varies in both time and space. Laboratory experiments have shown that gas and water permeabilities can differ for the same rock sample, but experiments are biased towards rocks that contain minerals that are expected react with the pore fluid (such as the reaction between liquid water and clay). We present here the first study that systematically compares the gas and water permeability of volcanic rocks. Our data show that permeabilities to argon gas and deionised water can differ by a factor between two and five in two volcanic rocks (basalt and andesite) over a confining pressure range from 2 to 50 MPa. We suggest here that the microstructural elements that offer the shortest route through the sample-estimated to have an average radius 0.1-0.5 μm using the Klinkenberg slip factor-are accessible to gas, but restricted or inaccessible to water. We speculate that water adsorption on the surface of these thin microstructural elements, assumed here to be tortuous/rough microcracks, reduces their effective radius and/or prevents access. These data have important implications for fluid flow and therefore the distribution and build-up of pore pressure within volcanic systems.

Fire clay

USGS Publications Warehouse

Virta, R.L.

2012-01-01

Five companies mined fire clay in four states in 2011. Production, based on a preliminary survey of the fire clay industry, was estimated to be 240 kt (265,000 st), valued at $7.68 million, an increase from 216 kt (238,000 st), valued at $6.12 million in 2010. Missouri was the leading producing state, followed by Texas, Washington and Ohio, in decreasing order by quantity.

Sm-Nd and Rb-Sr isotopic systematics of the Pea Ridge Fe-P deposit and related rocks, southeast Missouri

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marikos, M.A.; Barton, M.D.

1993-03-01

Pea ridge is a discordant Middle Proterozoic Fe-P deposit hosted in rhyolite tuffs and flows of the 1.4--1.5 Ga St. Francois terrane. Host rocks and the deposit are cut by basalt and aplite/pegmatite dikes. The deposit overlies a blind pluton which is partially surrounded by a trachytic ring complex. In the deposit, which is mined for Fe, early Qtz+Amph+Mag+Ap rock is cut by Mag+Ap+Qtz rock. Subsequently, portions of the deposit and host rocks were brecciated, oxidized and silicified to produce a complex suite of rocks enriched in Hem+Qtz+Ksp+Mu. Late breccia pipes/dikes cut the complex and were mineralized with Bar+Ksp+Flu+Chl+Cc+REE-phosphates. Sm/Ndmore » and Rb/Sr isotopic systematics have been studied to: (1) constrain source(s) of igneous rocks and deposit components, (2) refine ages of magmatism, mineralization, and later hydrothermal activity, (3) begin regional comparison of isotopic systematics in SE Missouri Fe deposits, and (4) complement ongoing Missouri DGLS/USGS studies. Fourteen combined Sm-Nd and Rb-Sr analyses were done on materials including two host rhyolites, two nearby trachytes, two gneiss samples representing plausible basement, two intramineral dikes, and six samples of mineralization.« less

Glowing clay: Real time tracing using a suite of novel clay based fluorescent tracers

NASA Astrophysics Data System (ADS)

Hardy, Robert; Quinton, John; Pates, Jackie; Coogan, Mike

2015-04-01

Clay is one of the most mobile fractions of soil due to its small particle size. It is also known to sorb many chemicals, such as nutrients (notably phosphorus), agrochemicals and heavy metals. The movement of clay is therefore linked with the transport and fate of these substances. A novel fluorescent clay tracing suite has been produced, together with an imaging technique. This suite consists of qualitative clay tracers, using rhodamine based fluorophores, and quantitative clay tracers, using metal based fluorophores. Efforts have also been made to allow integration of commercially available tracers, which are silt and sand sized. The clay tracers exploit the high affinity that montmorillonite has for Rhodamine B and Ru(bpy)3. This allows for an extremely thin layer of the fluorophore to be sorbed onto the clay's surface, in much that same way as materials in the natural environment will bind to clay. The tracer that is produced retains key chemical and physical properties of clay, such as size, shape and density. The retention of these micro-properties results in the retention of macro-properties, such as tendency to aggregate and cracking on drying. Imaging techniques have been developed to analyse these tracers. The imaging system uses diffused laser light to excite the tracer and a modified DSLR camera to image the soil surface. The images have been compiled into a time lapse video showing the movement of clay over the course of a rainfall event. This is the first time that the quantitative movement of clay has been recorded over a soil surface in real time. 4D data can be extracted from the images allowing the spatial location and intensity of tracer to be monitored over time, with mm precision and on the timescale of seconds. As the system can also work with a commercial tracer it is possible to investigate the movement of particles of almost any size and over a range of scales from soil box to hillside. This allows users to access this technique without

Rocks and geology in the San Francisco Bay region

USGS Publications Warehouse

Stoffer, Philip W.

2002-01-01

The landscape of the San Francisco Bay region is host to a greater variety of rocks than most other regions in the United States. This introductory guide provides illustrated descriptions of 46 common and important varieties of igneous, sedimentary, and metamorphic rock found in the region. Rock types are described in context of their identification qualities, how they form, and where they occur in the region. The guide also provides discussion about of regional geology, plate tectonics, the rock cycle, the significance of the selected rock types in relation to both earth history and the impact of mineral resources on the development in the region. Maps and text also provide information where rocks, fossils, and geologic features can be visited on public lands or in association with public displays in regional museums, park visitor centers, and other public facilities.

Scanning electron microscopy of clays and clay minerals

USGS Publications Warehouse

Bohor, B.F.; Hughes, R.E.

1971-01-01

The scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units—interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis—also are uniquely revealed by the SEM.Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types.

Frictional Properties of Opalinus Clay: Implications for Nuclear Waste Storage

NASA Astrophysics Data System (ADS)

Orellana, L. F.; Scuderi, M. M.; Collettini, C.; Violay, M.

2018-01-01

The kaolinite-bearing Opalinus Clay (OPA) is the host rock proposed in Switzerland for disposal of radioactive waste. However, the presence of tectonic faults intersecting the OPA formation put the long-term safety performance of the underground repository into question due to the possibility of earthquakes triggered by fault instability. In this paper, we study the frictional properties of the OPA shale. To do that, we have carried out biaxial direct shear experiments under conditions typical of nuclear waste storage. We have performed velocity steps (1-300 μm/s) and slide-hold-slide tests (1-3,000 s) on simulated fault gouge at different normal stresses (4-30 MPa). To establish the deformation mechanisms, we have analyzed the microstructures of the sheared samples through scanning electron microscopy. Our results show that peak (μpeak) and steady state friction (μss) range from 0.21 to 0.52 and 0.14 to 0.39, respectively, thus suggesting that OPA fault gouges are weak. The velocity dependence of friction indicates a velocity strengthening regime, with the friction rate parameter (a - b) that decreases with normal stress. Finally, the zero healing values imply a lack of restrengthening during interseismic periods. Taken together, if OPA fault reactivates, our experimental evidence favors an aseismic slip behavior, making the nucleation of earthquakes difficult, and long-term weakness, resulting in stable fault creeping over geological times. Based on the results, our study confirms the seismic safety of the OPA formation for a nuclear waste repository.

Coupling fluid dynamics and host-rock deformation associated with magma intrusion in the crust: Insights from analogue experiments

NASA Astrophysics Data System (ADS)

Kavanagh, J. L.; Dennis, D. J.

2014-12-01

Models of magma ascent in the crust tend to either consider the dynamics of fluid flow within intrusions or the associated host-rock deformation. However, these processes are coupled in nature, and so to develop a more complete understanding of magma ascent dynamics in the crust both need to be taken into account. We present a series of gelatine analogue experiments that use both Particle Image Velocimentry (PIV) and Digital Image Correlation (DIC) techniques to characterise the dynamics of fluid flow within intrusions and to quantify the associated deformation of the intruded media. Experiments are prepared by filling a 40x40x30 cm3 clear-Perspex tank with a low-concentration gelatine mixture (2-5 wt%) scaled to be of comparable stiffness to crustal strata. Fluorescent seeding particles are added to the gelatine mixture during its preparation and to the magma analogue prior to injection. Two Dantec CCD cameras are positioned outside the tank and a vertical high-power laser sheet positioned along the centre line is triggered to illuminate the seeding particles with short intense pulses. Dyed water (the magma analogue) injected into the solid gelatine from below causes a vertically propagating penny-shaped crack (dike) to form. Incremental and cumulative displacement vectors are calculated by cross-correlation between successive images at a defined time interval. Spatial derivatives map the fluid flow within the intrusion and associated strain and stress evolution of the host, both during dike propagation and on to eruption. As the gelatine deforms elastically at the experimental conditions, strain calculations correlate with stress. Models which couple fluid dynamics and host deformation make an important step towards improving our understanding of the dynamics of magma transport through the crust and to help constrain the tendency for eruption.

Genesis of sediment-hosted stratiform copper cobalt deposits, central African Copperbelt

NASA Astrophysics Data System (ADS)

Cailteux, J. L. H.; Kampunzu, A. B.; Lerouge, C.; Kaputo, A. K.; Milesi, J. P.

2005-07-01

The Neoproterozoic central African Copperbelt is one of the greatest sediment-hosted stratiform Cu-Co provinces in the world, totalling 140 Mt copper and 6 Mt cobalt and including several world-class deposits (⩾10 Mt copper). The origin of Cu-Co mineralisation in this province remains speculative, with the debate centred around syngenetic-diagenetic and hydrothermal-diagenetic hypotheses. The regional distribution of metals indicates that most of the cobalt-rich copper deposits are hosted in dolomites and dolomitic shales forming allochthonous units exposed in Congo and known as Congolese facies of the Katangan sedimentary succession (average Co:Cu = 1:13). The highest Co:Cu ratio (up to 3:1) occurs in ore deposits located along the southern structural block of the Lufilian Arc. The predominantly siliciclastic Zambian facies, exposed in Zambia and in SE Congo, forms para-autochthonous sedimentary units hosting ore deposits characterized by lower a Co:Cu ratio (average 1:57). Transitional lithofacies in Zambia (e.g. Baluba, Mindola) and in Congo (e.g. Lubembe) indicate a gradual transition in the Katangan basin during the deposition of laterally correlative clastic and carbonate sedimentary rocks exposed in Zambia and in Congo, and are marked by Co:Cu ratios in the range 1:15. The main Cu-Co orebodies occur at the base of the Mines/Musoshi Subgroup, which is characterized by evaporitic intertidal-supratidal sedimentary rocks. All additional lenticular orebodies known in the upper part of the Mines/Musoshi Subgroup are hosted in similar sedimentary rocks, suggesting highly favourable conditions for the ore genesis in particular sedimentary environments. Pre-lithification sedimentary structures affecting disseminated sulphides indicate that metals were deposited before compaction and consolidation of the host sediment. The ore parageneses indicate several generations of sulphides marking syngenetic, early diagenetic and late diagenetic processes. Sulphur isotopic

Chemical composition of sedimentary rocks in California and Hawaii

USGS Publications Warehouse

Hill, Thelma P.

1981-01-01

A compilation of published chemical analyses of sedimentary rocks of the United States was undertaken by the U.S. Geological Survey in 1952 to make available scattered data that are needed for a wide range of economic and scientific uses. About 20,000-25,000 chemical analyses of sedimentary rocks in the United States have been published. This report brings together 2,312 of these analyses from California and Hawaii. The samples are arranged by general lithologic characteristics and locality. Indexes of stratigraphy, rock name, commercial uses, and minor elements are provided. The sedimentary rocks are classified into groups and into categories according to the chemical analyses. The groups (A through F2) are defined by a system similar to that proposed by Brian Mason in 1952, in which the main parameters are the three major components of sedimentary rocks: (1) uncombined silica, (2) clay (R203 ? 3Si02 ? nH20), and (3) calcium-magnesium carbonate. The categories are based on the degree of admixture of these three major components with other components, such as sulfate, phos- phate, and iron oxide. Common-rock, mixed-rock, and special-rock categories apply to rocks consisting of 85 percent or more, 50-84 percent, and less than 49 percent, respectively, of the three major components combined. Maps show distribution of sample localities by States; triangular diagrams show the lithologic characteristics and classification groups. Cumulative-frequency curves of each constituent in each classification group of the common-rock and mixed-rock categories are also included. The numerous analyses may not adequately represent the geochemical nature of the rock types and formations of the region because of sampling bias. Maps showing distribution of sample localities indicate that many of the localities are in areas where, for economic or other reasons, special problems attracted interest. Most of the analyzed rocks tended to be fairly simple in composition - mainly mixtures of

Mineralogy and thermal properties of clay from Slatina (Ub, Serbia)

NASA Astrophysics Data System (ADS)

Milosevic, Maja; Logar, Mihovil; Kaludjerovic, Lazar; Jelic, Ivana

2017-04-01

The "Slatina" deposit, Ub, Serbia was opened in 1965 and represents one of few deposits exploited by "Kopovi" a.d., Ub, company. Deposit is composed of clay layers belonging to Neogene sediments that are widespread transgressive over granitoid rocks of Cer mountain and Paleozoic and Mesozoic sediments. Clay is mostly of illite-montmorillonite-kaolinite type and they are generally used as ceramic materials while some of the layers are used as fire-resistant materials. In this study we present mineralogical and thermal characterization of two samples to determine their application as industrial materials. Chemical and mineral composition was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD) on powder and oriented samples, infrared spectroscopy (IR) and granulometry. Cationic exchange capacity (CEC) and specific surface area (SSA) was determined using spectrophotometry and methylene blue (MB). Thermal properties where determined by gravimetry (120, 350, 600 and 1000 oC) and differential thermal analysis (DTA). Quantitative mineral composition obtained by Rietveld refinement of combined chemical and XRD data shows that the sample 1(SC) is mainly smectite-illite (45%) and kaolinite (14%) clay with 19% of quartz, 10% feldspars and 7% of limonite, while sample 2(SV) is smectite-illite (43%) and kaolinite (11%) clay with 10% of quartz, 15% feldspars and 7% of limonite. Both samples have low content of impurities (carbonate minerals). Medium grain size (μm) goes from 1.02 (SSA = 104 m2/g) for sample 1(SC) to 0.71 (SSA = 117 m2/g) for sample 2(SV) while their CEC is 12.7 and 14.9 mmol/100g for 1(SC) and 2(SV) respectively. IR spectra of the samples shows larger amount of smectite clays with quartz and carbonate minerals for both samples which is in accordance with XRD data. DTA data shows couple of events that are endothermic. First one (100-200 oC) is associated with loss of moisture and constitutive water, second

Mineralogy of Cretaceous/Tertiary boundary clays in the Chicxulub structure in northern Yucatan

NASA Technical Reports Server (NTRS)

Ming, D. W.; Sharpton, Virgil L.; Schuraytz, B. C.

1991-01-01

The Cretaceous/Tertiary (K/T) boundary clay layer is thought to be derived from ejecta material from meteorite impact, based on the anomalous concentrations of noble metals in the layer. Because of recent findings of a half-meter thick ejecta deposit at the K/T boundary in Haiti, efforts have focused on locating a large impact feature in the Caribbean and the Gulf of Mexico. One of the leading candidates for the site of a large impact is the Chicxulub structure located on the northern Yucatan Peninsula in Mexico. The Chicxulub structure is a subsurface zone of upper Cretaceous igneous rocks, carbonates, and breccias. The structure has been interpreted to be a 200 km diameter; however, there is some question to the size of the structure or to the fact that it even is an impact feature. Little is known about the mineralogy of this structure; the objective of this study was to determine the clay mineralogy of core samples from within the Chicxulub structure.

Comparison of tetrachloromethane sorption to an alkylammonium-clay and an alkyldiammonium-clay

USGS Publications Warehouse

Smith, J.A.; Jaffe, P.R.

1991-01-01

The interlamellar space of Wyoming bentonite (clay) was modified by exchanging either decyltrimethyl-ammonium (DTMA) or decyltrimethyldiammonium (DTMDA) cations for inorganic ions, and tetrachloromethane sorption to the resulting two organoclays from water was studied at 10, 20, and 35??C. Only one end of the 10-carbon alkyl chain of the DTMA cation is attached to the silica surface of the clay mineral, and tetrachloromethane sorption of DTMA-clay is characterized by isotherm linearity, noncompetitive sorption, weak solute uptake, and a relatively low heat of sorption. Both ends of the 10-carbon chain of the DTMDA cation are attached to the silica surface of the clay mineral, and tetrachloromethane sorption to DTMDA-clay is characterized by nonlinear isotherms, competitive sorption, strong solute uptake, and a relatively high, exothermic heat of sorption that varies as a function of the mass of tetrachloromethane sorbed. Therefore, the attachment of both ends of the alkyl chain to the interlamellar mineral surface appears to change the sorption mechanism from a partition-dominated process to an adsorption-dominated process. ?? 1991 American Chemical Society.

On the Theory of Solitons of Fluid Pressure and Solute Density in Geologic Porous Media, with Applications to Shale, Clay and Sandstone

NASA Astrophysics Data System (ADS)

Caserta, A.; Kanivetsky, R.; Salusti, E.

2017-11-01

We here analyze a new model of transients of pore pressure p and solute density ρ in geologic porous media. This model is rooted in the nonlinear wave theory, its focus is on advection and effect of large pressure jumps on strain. It takes into account nonlinear and also time-dependent versions of the Hooke law about stress, rate and strain. The model solutions strictly relate p and ρ evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e., the nonlinear "Burgers solitons". We, therefore, show that the actual transport process in porous rocks for large signals is not only the linear diffusion, but also a solitons presence could control the process. A test of a presence of solitons is applied to Pierre shale, Bearpaw shale, Boom clay and Oznam-Mugu silt and clay. An application about the presence of solitons for nuclear waste disposal and salt water intrusions is also discussed. Finally, in a kind of "theoretical experiment" we show that solitons could also be present in higher permeability rocks (Jordan and St. Peter sandstones), thus supporting the idea of a possible occurrence of osmosis also in sandstones.

Climatic Oscillations 10,000-155,000 yr B.P. at Owens Lake, California Reflected in Glacial Rock Flour Abundance and Lake Salinity in Core OL-92

NASA Astrophysics Data System (ADS)

Bischoff, James L.; Menking, Kirsten M.; Fitts, Jeffrey P.; Fitzpatrick, John A.

1997-11-01

Chemical analyses of the acid-soluble and clay-size fractions of sediment samples (1500-yr resolution) reveal oscillations of lake salinity and of glacial advances in core OL-92 back to 155,000 yr B.P. Relatively saline conditions are indicated by the abundance of carbonate and smectite (both pedogenic and authigenic), reflected by Ca, Sr, and Mg in the acid-soluble suite, and by Cs 2O, excess MgO, and LOI (loss on ignition) in the clay-size fraction. Rock flour produced during glacial advances is represented by the abundance of detrital plagioclase and biotite in the clay-size fraction, the ratio of which remains essentially constant over the entire time span. These phases are quantitatively represented by Na 2O, TiO 2, Ba, and Mn in the clay fraction. The rock-flour record indicates two major ice-advances during the penultimate glacial cycle corresponding to marine isotope stage (MIS) 6, no major advances during the last interglaciation (entire MIS 5), and three major advances during the last glacial cycle (MIS 2, 3, and 4). The ages of the latter three correspond rather well to 36Cl dates reported for Sierra Nevada moraines. The onset of the last interglaciation is shown by abrupt increases in authigenic CaCO 3and an abrupt decrease in rock flour, at about 118,000 yr B.P. according to our time scale. In contrast, the boundary appears to be gradual in the δ 18O record in which the change from light to heavy values begins at about 140,000 yrs B.P. The exact position of the termination, therefore, may be proxy-dependent. Conditions of high carbonate and low rock flour prevailed during the entire period from 118,000 yr B.P. until the glacial advance at 53,000 yr B.P. signaled the end of this long interglaciation.

The carbonaceous phyllite rock-hosted Pedra Verde copper mine, Borborema Province, Brazil: Stable isotope constraints, structural controls and metallogenic evolution

NASA Astrophysics Data System (ADS)

da Silva Nogueira de Matos, José Henrique; Saraiva dos Santos, Ticiano José; Virgínia Soares Monteiro, Lena

2017-12-01

The Pedra Verde Copper Mine is located in the Viçosa do Ceará municipality, State of Ceará, NE Brazil. The copper mineralization is hosted by the Pedra Verde Phyllite, which is a carbonaceous chlorite-calcite phyllite with subordinate biotite. It belongs to the Neoproterozoic Martinópole Group of the Médio Coreaú Domain, Borborema Province. The Pedra Verde deposit is stratabound and its ore zoning is conspicuous, according to the following sequence, from bottom to top: marcasite/pyrite, native silver, chalcopyrite, bornite, chalcocite, native copper and hematite. Barite and carbonaceous material are reported in ore zones. Zoning reflects the ore formation within a redox boundary developed due to the interaction between oxidized copper- and sulfate-bearing fluids and the reduced phyllite. Structural control on mineralization is evidenced by the association of the ore minerals with veins, hinge folds, shadow pressures, and mylonitic foliation. It was mainly exercised by a dextral transcurrent shear zone developed during the third deformational stage identified in the Médio Coreaú Domain between 590 Ma and 570 Ma. This points to the importance of epigenetic, post-metamorphic deformational events for ore formation. Oxygen isotopic composition (δ18OH2O = 8.94 to 11.28‰, at 250 to 300 °C) estimated for the hydrothermal fluids in equilibrium with calcite indicates metamorphic or evolved meteoric isotopic signatures. The δ13CPDB values (-2.60 to -9.25‰) obtained for hydrothermal calcite indicate mixing of carbon sources derived from marine carbonate rocks and carbonaceous material. The δ34SCDT values (14.88 to 36.91‰) of sulfides suggest evaporites as sulfate sources or a closed system in relation to SO42- availability to form H2S. Carbonaceous matter had a key role in thermochemical sulfate processes and sulfide precipitation. The Pedra Verde Copper Mine is considered the first stratabound meta-sedimentary rock-hosted copper deposit described in Brazil

EPITHERMAL GOLD-SILVER MINERALIZATION RELATED TO VOLCANIC SUBSIDENCE IN THE CUSTER GRABEN, CUSTER COUNTY, IDAHO.

USGS Publications Warehouse

Johnson, Kathleen M.; McIntyre, David H.

1984-01-01

The Custer graben is a 13 by 32 km northeast-trending volcano-tectonic graben in the Challis volcanic field of central Idaho. Andesites, rhyolites, and associated pyroclastic rocks host vein and disseminated gold-silver deposits that are localized along discrete northeast- and northwest-trending fracture zones. Ore minerals in vein deposits are electrum, native gold and silver, chalcopyrite, and various sulfosalts in a gangue of pyrite and fine-grained quartz. At the Sunbeam Mine, near the center of the graben, vein and disseminated gold-silver mineralization occurred in hydrothermally altered rhyolite and pyroclastic rocks. The host rock has been pervasively silicified, and the feldspars altered to clay minerals. Analyses of surface and drill-core samples show that altered rocks are variably enriched in gold, silver, molybdenum, arsenic, zirconium, and selenium. Intense silicification is shown by SiO//2 values at high as 93%.

Surface Properties and Permeability of Poly(Vinylidene Fluoride)-Clays (PVDF/Clays) Composite Membranes

NASA Astrophysics Data System (ADS)

Pramono, E.; Ahdiat, M.; Simamora, A.; Pratiwi, W.; Radiman, C. L.; Wahyuningrum, D.

2017-07-01

Surface properties are important factors that determine the performance of ultrafiltration membranes. This study aimed to investigate the effects of clay addition on the surface properties and membrane permeability of PVDF (poly-vinylidene fluoride) membranes. Three types of clay with different particle size were used in this study, namely montmorillonite-MMT, bentonite-BNT and cloisite 15A-CLS. The PVDF-clay composite membranes were prepared by phase inversion method using PEG as additive. The hydrophobicity of membrane surface was characterized by contact angle. The membrane permeability was determined by dead- end ultrafiltration with a trans-membrane pressure of 2 bars. In contact angle measurement, water contact angle of composite membranes is higher than PVDF membrane. The addition of clays decreased water flux but increased of Dextran rejection. The PVDF-BNT composite membranes reach highest Dextran rejection value of about 93%. The type and particle size of clay affected the hydrophobicity of membrane surface and determined the resulting membrane structure as well as the membrane performance.

Role of rock texture and mineralogy on the hydrology and geochemistry of three neutral-drainage mesoscale experimental waste rock piles at the Antamina Mine, Peru

NASA Astrophysics Data System (ADS)

Peterson, H.; Bay, D. S.; Beckie, R. D.; Mayer, K. U.; Klein, B.; Smith, L.

2009-12-01

An ongoing study at the Antamina Cu-Zn-Mo mine in Peru investigates the hydrology and geochemistry of heterogeneous waste rock at multiple scales. Three of five instrumented mesoscale experimental waste rock piles (36m X 36m X 10m high) were constructed between 2006 and 2008. The coarsest-grained Pile 1 exhibits rapid, intense response to rain and returns to residual saturation relatively quickly, suggesting a significant influence of preferential flow in addition to high-conductivity matrix flow. Pile 2, the finest-grained of the three piles, exhibits signals from rain events that are significantly delayed and muted in comparison to those from Pile 1. Except for in the finest size fractions, the particle size distribution of Pile 3 closely resembles that of Pile 2, yet Pile 3 responds to rain events more similarly to Pile 1 than Pile 2. The presence of large boulders in Pile 3 could facilitate preferential flow, either through surface flow effects across boulders or by contributing to the formation of unfilled void space acting as macropores at high infiltration rates. The rapid rain event response of Pile 3 could also be attributed to a silt-clay percentage that is similar to Pile 1, which is less than half of the silt-clay percentage observed in Pile 2 (i.e., ~3%, ~8.5%, and ~4% for Piles 1, 2 and 3, respectively). For each of the three piles, the pH of effluent collected from bottom lysimeters and internal pore water sampled with suction lysimeters has remained circumneutral, with notable maximum concentrations of 2.8 mg/L Zn from Pile 1, which is comprised of slightly reactive hornfels and marble waste rock; 13.4 mg/L Zn and 22.7 mg/L Mo from Pile 2, comprised of reactive intrusive waste rock; and 42.5 mg/L Zn from Pile 3, comprised of reactive exoskarn waste rock. Ongoing work includes analysis of two additional mixed-rock experimental piles, studies to investigate the role of microbes on metal release (Dockrey et al., this session), analysis of pore gas

Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah

USGS Publications Warehouse

Jackson, M.D.; Pollard, D.D.

1990-01-01

A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85 and 3.0 km, respectively. These mountains record successive stages in the inflation of near-surface diorite intrusions that are probably laccolithic in origin. The host rocks deformed along networks of outcrop-scale faults, or deformation bands, marked by crushed grains, consolidation of the porous sandstone and small displacements of sedimentary beds. Zones of deformation bands oriented parallel to the beds and formation contacts subdivided the overburden into thin mechanical layers that slipped over one another during doming. Measurements of outcrop-scale fault populations at the three mountains reveal a network of faults that strikes at high angles to sedimentary beds which themselves strike tangentially about the domes. These faults have normal and reverse components of slip that accommodated bending and stretching strains within the strata. An early stage of this deformation is displayed at Mount Holmes, where states of stress computed from three fault samples correlate with the theoretical distribution of stresses resulting from bending of thin, circular, elastic plates. Field observations and analysis of frictional driving stresses acting on horizontal planes above an opening-mode dislocation, as well as the paleostress analysis of faulting, indicate that bedding-plane slip and layer flexure were important components of the early deformation. As the amplitude of doming increased, radial and circumferential stretching of the strata and rotation of the older faults in the steepening limbs of the domes increased the complexity of the fault patterns. Steeply-dipping, map-scale faults with dip-slip displacements indicate a late-stage jostling of major blocks over the central

Effects of complexation between organic matter (OM) and clay mineral on OM pyrolysis

NASA Astrophysics Data System (ADS)

Bu, Hongling; Yuan, Peng; Liu, Hongmei; Liu, Dong; Liu, Jinzhong; He, Hongping; Zhou, Junming; Song, Hongzhe; Li, Zhaohui

2017-09-01

The stability and persistence of organic matter (OM) in source rocks are of great significance for hydrocarbon generation and the global carbon cycle. Clay-OM associations commonly occur in sedimentation and diagenesis processes and can influence the pyrolytic behaviors of OM. In this study, clay-OM complexes, i.e., interlayer clay-OM complexes and clay-OM mixture, were prepared and exposed to high-pressure pyrolysis conditions in confined gold capsule reactors to assess variations in OM pyrolysis products in the presence of clay minerals. Three model organic compounds, octadecanoic acid (OA), octadecy trimethyl ammonium bromide (OTAB), and octadecylamine (ODA), were employed and montmorillonite (Mt) was selected as the representative clay mineral. The solid acidity of Mt plays a key role in affecting the amount and composition of the pyrolysis gases generated by the clay-OM complexes. The Brønsted acid sites significantly promote the cracking of hydrocarbons through a carbocation mechanism and the isomerization of normal hydrocarbons. The Lewis acid sites are primarily involved in the decarboxylation reaction during pyrolysis and are responsible for CO2 generation. Mt exhibits either a catalysis effect or pyrolysis-inhibiting during pyrolysis of a given OM depending on the nature of the model organic compound and the nature of the clay-OM complexation. The amounts of C1-5 hydrocarbons and CO2 that are released from the Mt-OA and Mt-ODA complexes were higher than those of the parent OA and ODA, respectively, indicating a catalysis effect of Mt. In contrast, the amount of C1-5 hydrocarbons produced from the pyrolysis of Mt-OTAB complexes was lower than that of OTAB, which we attribute to an inhibiting effect of Mt. This pyrolysis-inhibiting effect works through the Hoffmann elimination that is promoted by the catalysis of the Brønsted acid sites of Mt, therefore releasing smaller amounts of gas hydrocarbons than the nucleophilic reaction that is induced by the

Columns in Clay

ERIC Educational Resources Information Center

Leenhouts, Robin

2010-01-01

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

Clay energetics in chemical evolution

NASA Technical Reports Server (NTRS)

Coyne, L. M.

1986-01-01

Clays have been implicated in the origin of terrestrial life since the 1950's. Originally they were considered agents which aid in selecting, concentrating and promoting oligomerization of the organic monomeric substituents of cellular life forms. However, more recently, it has been suggested that minerals, with particular emphasis on clays, may have played a yet more fundamental role. It has been suggested that clays are prototypic life forms in themselves and that they served as a template which directed the self-assembly of cellular life. If the clay-life theory is to have other than conceptual credibility, clays must be shown by experiment to execute the operations of cellular life, not only individually, but also in a sufficiently concerted manner as to produce some semblance of the functional attributes of living cells. Current studies are focussed on the ability of clays to absorb, store and transfer energy under plausible prebiotic conditions and to use this energy to drive chemistry of prebiotic relevance. Conclusions of the work are applicable to the role of clays either as substrates for organic chemistry, or in fueling their own life-mimetic processes.

Hydrogeology of a fractured shale (Opalinus Clay): Implications for deep geological disposal of radioactive wastes

NASA Astrophysics Data System (ADS)

Gautschi, Andreas

2001-01-01

As part of the Swiss programme for high-level radioactive-waste disposal, a Jurassic shale (Opalinus Clay) is being investigated as a potential host rock. Observations in clay pits and the results of a German research programme focusing on hazardous waste disposal have demonstrated that, at depths of 10-30 m, the permeability of the Opalinus Clay decreases by several orders of magnitude. Hydraulic tests in deeper boreholes (test intervals below 300 m) yielded hydraulic conductivities <10-12 m/s, even though joints and faults were included in some of the test intervals. These measurements are consistent with hydrogeological data from Opalinus Clay sections in ten tunnels in the Folded Jura of northern Switzerland. Despite extensive faulting, only a few indications of minor water inflow were encountered in more than 6,600 m of tunnel. All inflows were in tunnel sections where the overburden is less than 200 m. The hydraulic data are consistent with clay pore-water hydrochemical and isotopic data. The extensive hydrogeological data base - part of which derives from particularly unfavourable geological environments - provides arguments that advective transport through faults and joints is not a critical issue for the suitability of Opalinus Clay as a host rock for deep geological waste disposal. Résumé. Dans le cadre du programme suisse de stockage de déchets hautement radioactifs, une formation argileuse du Jurassique, l'argile à Opalinus, a été étudiée en tant que roche hôte potentielle. Des observations dans des cavités dans l'argile et les résultats du programme de recherche allemand consacré au stockage de déchets à risques ont démontré que, à des profondeur de 10 à 30 m, la perméabilité des argiles à Opalinus décroît de plusieurs ordres de grandeur. Des essais hydrauliques dans des forages plus profonds (intervalles de test á une profondeur de plus de 300 m) ont donné des conductivités hydrauliques inférieures à 10-12 m/s, m

Altered rock spectra in the visible and near infrared. [western Nevada

NASA Technical Reports Server (NTRS)

Hunt, G. R.; Ashley, R. P. (Principal Investigator)

1979-01-01

The author has identified the following significant results. Visible and near-infrared (0.35 to 2.5 micron m) bidirectional reflection spectra recorded for a suite of well-characterized hydrothermally altered rock samples typically display well defined bands caused by both electronic and vibrational processes in the individual mineral constituents. Electronic transitions in the iron-bearing constituent minerals produce diagnostic minima near 0.43, 0.65, 0.85, and 0.93 micron m. Vibrational transitions in clay and water-bearing mineral constituents produce characteristic single or multiple features over limited spectral ranges near 1.4, 1.75, 1.9, 2.2, and 2.35 micron m. The most abundant feature-producing minerals present in these rocks are hematite, goethite, and alunite. Others frequently present are jarosite, kaolinite, potassium micas, pyrophyllite, montmorillonite, diaspore, and gypsum. The spectral region near 2.2 micron m is particularly important for detecting altered rocks by remote sensing.

Occurrence of Tourmaline in Metasedimentary Rocks of the Isua Supracrustal Belt, Greenland: Implications for Ribose Stabilization in Hadean Marine Sediments.

PubMed

Mishima, Shinpei; Ohtomo, Yoko; Kakegawa, Takeshi

2016-06-01

Abiotic formation of RNA was important for the emergence of terrestrial life, but the acknowledged difficulties of generating and stabilizing ribose have often raised questions regarding how the first RNA might have formed. Previous researchers have proposed that borate could have stabilized ribose; however, the availability of borate on the early Earth has been the subject of intense debate. In order to examine whether borate was available on the early Earth, this study examined metasedimentary rocks from the Isua Supracrustal Belt. Garnet, biotite, and quartz comprise the major constituents of the examined rocks. Field relationships and the chemical compositions of the examined rocks suggest sedimentary origin. The present study found that garnet crystals contain a number of inclusions of tourmaline (a type of borosilicate mineral). All tourmaline crystals are Fe-rich and categorized as schorl. Both garnet and tourmaline often contain graphite inclusions and this close association of tourmaline with garnet and graphite has not been recognized previously. Garnet-biotite and graphite geothermometers suggest that the tourmaline in garnet experienced peak metamorphic conditions (~500 °C and 5 kbar). The mineralogical characteristics of the tourmaline and the whole rock composition indicate that the tourmaline formed authigenically in the sediment during diagenesis and/or early metamorphism. Clay minerals in modern sediments have the capability to adsorb and concentrate borate, which could lead to boron enrichment during diagenesis, followed by tourmaline formation under metamorphic conditions. Clay minerals, deposited on the early Archean seafloor, were the precursors of the garnet and biotite in the examined samples. The studied tourmaline crystals were most likely formed in the same way as modern tourmaline in marine sediments. Therefore, boron enrichment by clays must have been possible even during the early Archean. Thus, similar enrichment could have been

Reducing the Cation Exchange Capacity of Lithium Clay to Form Better Dispersed Polymer-Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Liang, Maggie

2004-01-01

Polymer-clay nanocomposites have exhibited superior strength and thermo- oxidative properties as compared to pure polymers for use in air and space craft; however, there has often been difficulty completely dispersing the clay within the matrices of the polymer. In order to improve this process, the cation exchange capacity of lithium clay is first lowered using twenty-four hour heat treatments of no heat, 130 C, 150 C, or 170 C to fixate the lithium ions within the clay layers so that they are unexchangeable. Generally, higher temperatures have generated lower cation exchange capacities. An ion exchange involving dodecylamine, octadecylamine, or dimethyl benzidine (DMBZ) is then employed to actually expand the clay galleries. X-ray diffraction and transmission electron microscopy can be used to determine whether the clay has been successfully exfoliated. Finally, resins of DMBZ with clay are then pressed into disks for characterization using dynamic mechanical analyzer and oven- aging techniques in order to evaluate their glass transition, modulus strength, and thermal-oxidative stability in comparison to neat DMBZ. In the future, they may also be tested as composites for flexural and laminar shear strength.

Hollow Cylinder Tests on Boom Clay: Modelling of Strain Localization in the Anisotropic Excavation Damaged Zone

NASA Astrophysics Data System (ADS)

François, Bertrand; Labiouse, Vincent; Dizier, Arnaud; Marinelli, Ferdinando; Charlier, Robert; Collin, Frédéric

2014-01-01

Boom Clay is extensively studied as a potential candidate to host underground nuclear waste disposal in Belgium. To guarantee the safety of such a disposal, the mechanical behaviour of the clay during gallery excavation must be properly predicted. In that purpose, a hollow cylinder experiment on Boom Clay has been designed to reproduce, in a small-scale test, the Excavation Damaged Zone (EDZ) as experienced during the excavation of a disposal gallery in the underground. In this article, the focus is made on the hydro-mechanical constitutive interpretation of the displacement (experimentally obtained by medium resolution X-ray tomography scanning). The coupled hydro-mechanical response of Boom Clay in this experiment is addressed through finite element computations with a constitutive model including strain hardening/softening, elastic and plastic cross-anisotropy and a regularization method for the modelling of strain localization processes. The obtained results evidence the directional dependency of the mechanical response of the clay. The softening behaviour induces transient strain localization processes, addressed through a hydro-mechanical second grade model. The shape of the obtained damaged zone is clearly affected by the anisotropy of the materials, evidencing an eye-shaped EDZ. The modelling results agree with experiments not only qualitatively (in terms of the shape of the induced damaged zone), but also quantitatively (for the obtained displacement in three particular radial directions).

CEC-normalized clay-water sorption isotherm

NASA Astrophysics Data System (ADS)

Woodruff, W. F.; Revil, A.

2011-11-01

A normalized clay-water isotherm model based on BET theory and describing the sorption and desorption of the bound water in clays, sand-clay mixtures, and shales is presented. Clay-water sorption isotherms (sorption and desorption) of clayey materials are normalized by their cation exchange capacity (CEC) accounting for a correction factor depending on the type of counterion sorbed on the mineral surface in the so-called Stern layer. With such normalizations, all the data collapse into two master curves, one for sorption and one for desorption, independent of the clay mineralogy, crystallographic considerations, and bound cation type; therefore, neglecting the true heterogeneity of water sorption/desorption in smectite. The two master curves show the general hysteretic behavior of the capillary pressure curve at low relative humidity (below 70%). The model is validated against several data sets obtained from the literature comprising a broad range of clay types and clay mineralogies. The CEC values, derived by inverting the sorption/adsorption curves using a Markov chain Monte Carlo approach, are consistent with the CEC associated with the clay mineralogy.

Mercury isotope constraints on the source for sediment-hosted lead-zinc deposits in the Changdu area, southwestern China

NASA Astrophysics Data System (ADS)

Xu, Chunxia; Yin, Runsheng; Peng, Jiantang; Hurley, James P.; Lepak, Ryan F.; Gao, Jianfeng; Feng, Xinbin; Hu, Ruizhong; Bi, Xianwu

2018-03-01

The Lanuoma and Cuona sediment-hosted Pb-Zn deposits hosted by Upper Triassic limestone and sandstone, respectively, are located in the Changdu area, SW China. Mercury concentrations and Hg isotopic compositions from sulfide minerals and potential source rocks (e.g., the host sedimentary rocks and the metamorphic basement) were investigated to constrain metal sources and mineralization processes. In both deposits, sulfide minerals have higher mercury (Hg) concentrations (0.35 to 1185 ppm) than the metamorphic basement rocks (0.05 to 0.15 ppm) and sedimentary rocks (0.02 to 0.08 ppm). Large variations of mass-dependent fractionation (3.3‰ in δ202Hg) and mass-independent fractionation (0.3‰ in Δ199Hg) of Hg isotopes were observed. Sulfide minerals have Hg isotope signatures that are similar to the hydrothermal altered rocks around the deposit, and similar to the metamorphic basement, but different from barren sedimentary rocks. The variation of Δ199Hg suggests that Hg in sulfides was mainly derived from the underlying metamorphic basement. Mercury isotopes could be a geochemical tracer in understanding metal sources in hydrothermal ore deposits.

Clay Portrait Boxes

ERIC Educational Resources Information Center

Wilbert, Nancy Corrigan

2009-01-01

In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

NASA Astrophysics Data System (ADS)

Lackschewitz, K. S.; Devey, C. W.; Stoffers, P.; Botz, R.; Eisenhauer, A.; Kummetz, M.; Schmidt, M.; Singer, A.

2004-11-01

During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ˜250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ˜300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly

Clay Animals and Their Habitats

ERIC Educational Resources Information Center

Adamson, Kay

2010-01-01

Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

Anisotropic Behaviour of Opalinus Clay Through Consolidated and Drained Triaxial Testing in Saturated Conditions

NASA Astrophysics Data System (ADS)

Favero, Valentina; Ferrari, Alessio; Laloui, Lyesse

2018-05-01

This paper investigates the anisotropic hydro-mechanical behaviour of Opalinus Clay shale, the host material currently being considered for the construction of a nuclear waste repository in Switzerland. Consolidated and drained triaxial tests on Opalinus Clay from the Mont Terri URL have been conducted in order to derive information on its strength and stiffness properties. Opalinus Clay specimens were tested both parallel to bedding (P-specimens) and perpendicular to bedding (S-specimens). The considered effective confining stress range (from 2 to 12 MPa) has been selected in order to reproduce possible in situ stress conditions for the repository. In this work, particular attention has been paid to the experimental procedure in order to ensure consolidated conditions and avoid generation of unwanted excess pore water pressure during drained shearing. The Skempton B parameter has been determined for all the tested specimens in order to ensure saturation. Both single-stage and multistage triaxial testing procedures were adopted in the experimental campaign. The results of the triaxial tests highlight an anisotropic elastic response of Opalinus Clay: S-specimens present a more compliant behaviour than P-specimens. The values of the Young modulus are found to increase with the increase in mean effective stress. The analysis of the peak and ultimate shear strength results reveals that the material behaves in a similar manner regardless of the considered direction of loading (P and S directions) with respect to the bedding orientation. Peak and ultimate failure envelopes for Opalinus Clay were derived for the investigated stress range.

Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

PubMed

Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

2002-07-01

In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

Weathering profiles in soils and rocks on Earth and Mars

NASA Astrophysics Data System (ADS)

Hausrath, E.; Adcock, C. T.; Bamisile, T.; Baumeister, J. L.; Gainey, S.; Ralston, S. J.; Steiner, M.; Tu, V.

2017-12-01

Interactions of liquid water with rock, soil, or sediments can result in significant chemical and mineralogical changes with depth. These changes can include transformation from one phase to another as well as translocation, addition, and loss of material. The resulting chemical and mineralogical depth profiles can record characteristics of the interacting liquid water such as pH, temperature, duration, and abundance. We use a combined field, laboratory, and modeling approach to interpret the environmental conditions preserved in soils and rocks. We study depth profiles in terrestrial field environments; perform dissolution experiments of primary and secondary phases important in soil environments; and perform numerical modeling to quantitatively interpret weathering environments. In our field studies we have measured time-integrated basaltic mineral dissolution rates, and interpreted the impact of pH and temperature on weathering in basaltic and serpentine-containing rocks and soils. These results help us interpret fundamental processes occurring in soils on Earth and on Mars, and can also be used to inform numerical modeling and laboratory experiments. Our laboratory experiments provide fundamental kinetic data to interpret processes occurring in soils. We have measured dissolution rates of Mars-relevant phosphate minerals, clay minerals, and amorphous phases, as well as dissolution rates under specific Mars-relevant conditions such as in concentrated brines. Finally, reactive transport modeling allows a quantitative interpretation of the kinetic, thermodynamic, and transport processes occurring in soil environments. Such modeling allows the testing of conditions under longer time frames and under different conditions than might be possible under either terrestrial field or laboratory conditions. We have used modeling to examine the weathering of basalt, olivine, carbonate, phosphate, and clay minerals, and placed constraints on the duration, pH, and solution

Heavy metal migration in soils and rocks at historical smelting sites.

PubMed

Maskall, J; Whitehead, K; Thornton, I

1995-09-01

The vertical migration of metals through soils and rocks was investigated at five historical lead smelting sites ranging in age between 220 and 1900 years. Core samples were taken through metal-contaminated soils and the underlying strata. Concentration profiles of lead and zinc are presented from which values for the distances and rates of migration have been derived. Slag-rich soil horizons contain highly elevated metal concentrations and some contamination of underlying strata has occurred at all sites. However, the amounts of lead and zinc that have migrated from soils and been retained at greater depths are comparatively low. This low metal mobility in contaminated soils is partly attributed to the elevation of soil pH by the presence of calcium and carbonate originating from slag wastes and perhaps gangue minerals. Distances and rates of vertical migration were higher at those sites with soils underlain by sandstone than at those with soils underlain by clay. For sites with the same parent material, metal mobility appears to be increased at lower soil pH. The mean migration rates for lead and zinc reach maxima of 0.75 and 0.46 cm yr(-1) respectively in sandstone at Bole A where the elements have moved mean distances of 4.3 and 2.6 m respectively. There is some evidence that metal transport in the sandstone underlying Bole A and Cupola B occurs preferentially along rock fractures. The migration of lead and zinc is attenuated by subsurface clays leading to relatively low mean migration rates which range from 0.03 to 0.31 cm yr(-1) with many values typical of migration solely by diffusion. However, enhanced metal migration in clays at Cupola A suggest a preferential transport mechanism possibly in cracks or biopores.

Reappraisal of hydrocarbon biomarkers in Archean rocks

PubMed Central

French, Katherine L.; Hallmann, Christian; Hope, Janet M.; Schoon, Petra L.; Zumberge, J. Alex; Hoshino, Yosuke; Peters, Carl A.; George, Simon C.; Love, Gordon D.; Brocks, Jochen J.; Buick, Roger; Summons, Roger E.

2015-01-01

Hopanes and steranes found in Archean rocks have been presented as key evidence supporting the early rise of oxygenic photosynthesis and eukaryotes, but the syngeneity of these hydrocarbon biomarkers is controversial. To resolve this debate, we performed a multilaboratory study of new cores from the Pilbara Craton, Australia, that were drilled and sampled using unprecedented hydrocarbon-clean protocols. Hopanes and steranes in rock extracts and hydropyrolysates from these new cores were typically at or below our femtogram detection limit, but when they were detectable, they had total hopane (<37.9 pg per gram of rock) and total sterane (<32.9 pg per gram of rock) concentrations comparable to those measured in blanks and negative control samples. In contrast, hopanes and steranes measured in the exteriors of conventionally drilled and curated rocks of stratigraphic equivalence reach concentrations of 389.5 pg per gram of rock and 1,039 pg per gram of rock, respectively. Polycyclic aromatic hydrocarbons and diamondoids, which exceed blank concentrations, exhibit individual concentrations up to 80 ng per gram of rock in rock extracts and up to 1,000 ng per gram of rock in hydropyrolysates from the ultraclean cores. These results demonstrate that previously studied Archean samples host mixtures of biomarker contaminants and indigenous overmature hydrocarbons. Therefore, existing lipid biomarker evidence cannot be invoked to support the emergence of oxygenic photosynthesis and eukaryotes by ∼2.7 billion years ago. Although suitable Proterozoic rocks exist, no currently known Archean strata lie within the appropriate thermal maturity window for syngenetic hydrocarbon biomarker preservation, so future exploration for Archean biomarkers should screen for rocks with milder thermal histories. PMID:25918387

Iridium contents in the Late Cretaceous-Early Tertiary clays in relation to the K/T boundary, North Jordan

NASA Astrophysics Data System (ADS)

Abboud, Iyad Ahmed

2016-06-01

The mineralogy, lithology, and geochemistry of five discrete laminations across the K/T boundary of clayey shale at the Yarmouk River area, Jordan, were examined. There were no marked changes in the mineralogy of the clayey shale within the K/T boundary. This outcrop consists of more than 100 m of Maastrichtian oil shale overlying about 20 m limestone. Marly limestone included many clay laminations from organic and volcanic origins, which are considered an evidence of the K/T boundary through detected iridium anomalies. Any of these particular lamellae range from 2 mm to 5 mm in thickness. Smectite was the predominant clay mineral in smectitic shale laminations. It was located at eight meters above the K/T boundary and includes some anomalous concentrations of iridium and traces of other elements. The analysis of geochemical platinum group at the K/T boundary clays showed anomalous enrichments of iridium, compared with other carbonate rocks as a result of weathering processes of oil shale, or through concentration from weathering of basalt flows, but not pointing to an impact process. The clays in late Maastrichtian have Ir-Sc prevailed anomalies and synchronize with increasing of terrigenous and volcanogenic traced elements. Kaolin, smectite, and volkonskoite were the dominant clay minerals at the K/T boundary with high concentrations of iridium. The concentration levels of iridium in some laminations of the Yarmouk sediments ranged between 1.6 and 7.8 ppb.

Physical and mechanical properties of quarry dust waste incorporated into fired clay brick

NASA Astrophysics Data System (ADS)

Kadir, A. A.; Hassan, M. I. H.; Sarani, N. A.; Rahim, A. S. Abdul; Ismail, N.

2017-04-01

A large amount of quarry dust waste is dispose into landfills every year. This waste was obtained as a by-product during the production of aggregates through the crushing process of rocks in rubble crusher units. The increasing value of waste will have significant impact towards health and environment. Recycling such wastes by incorporating them into building materials is a practical solution for pollution problem. Therefore, this research was to examine the possibility of quarry dust to be incorporated in fired clay bricks. In this research, the composition and concentration of heavy metals were determined by using X-Ray Fluorescence Spectrometer (XRF). The research also consists of physical and mechanical properties of the fired clay bricks by utilizing quarry dust waste. Brick was manufactured by incorporating different percentages of quarry dust waste which are 0%, 10%, 20% and 30%. All bricks sample was tested with physical and mechanical properties which were density, shrinkage, initial rate of suction (IRS) and compressive strength of the fired bricks. Furthermore, the density and shrinkage were also in standard range. All physical and mechanical results were complied with the BS 3921:1985 standard. The comprehensive experimental work described in this research investigated the possibility of incorporating quarry dust into fired clay bricks. These materials could be an alternative low cost material for brick and at the same time provide a new disposal method for the waste.

Polymer based nanocomposites with nanofibers and exfoliated clay

NASA Technical Reports Server (NTRS)

Meador, Michael A.; Reneker, Darrell H.

2005-01-01

Polymer solutions, containing clay sheets, were electrospun into nanofibers and microfibers that contained clay sheets inside. Controllable removal of polymer by plasma etching from the surface of fibers revealed the arrangement of clay. The shape, flexibility, size distribution and arrangement of clay sheets were observed by transmission and scanning electron microscopy. The clay sheets were partially aligned in big fibers with normal direction of clay sheets perpendicular to fiber axis. Crumpling of clay sheets inside fibers was observed when the fiber diameter was comparable to the lateral size of clay sheets. Single sheets of clay were observed both by catching clay sheets dispersed in water with electrospun nanofiber mats and by the deliberate removal of most of the polymer in the fibers. Thin, flexible gas barrier films, that are reasonably strong, were assembled from clay sheets and polymer nanofibers. Structure of composite films was characterized with scanning electron microscopy. Continuous film of clay sheets were physically attached to the surface of fiber mats. Spincoating film of polymer and clay sheets was reinforced by electrospun fiber scaffold. Certain alignment of clay sheets was observed in the vicinity of fibers.

Using Neutrons to Study Fluid-Rock Interactions in Shales

NASA Astrophysics Data System (ADS)

DiStefano, V. H.; McFarlane, J.; Anovitz, L. M.; Gordon, A.; Hale, R. E.; Hunt, R. D.; Lewis, S. A., Sr.; Littrell, K. C.; Stack, A. G.; Chipera, S.; Perfect, E.; Bilheux, H.; Kolbus, L. M.; Bingham, P. R.

2015-12-01

Recovery of hydrocarbons by hydraulic fracturing depends on complex fluid-rock interactions that we are beginning to understand using neutron imaging and scattering techniques. Organic matter is often thought to comprise the majority of porosity in a shale. In this study, correlations between the type of organic matter embedded in a shale and porosity were investigated experimentally. Selected shale cores from the Eagle Ford and Marcellus formations were subjected to pyrolysis-gas chromatography, Differential Thermal Analysis/Thermogravimetric analysis, and organic solvent extraction with the resulting affluent analyzed by gas chromatography-mass spectrometry. The pore size distribution of the microporosity (~1 nm to 2 µm) in the Eagle Ford shales was measured before and after solvent extraction using small angle neutron scattering. Organics representing mass fractions of between 0.1 to 1 wt.% were removed from the shales and porosity generally increased across the examined microporosity range, particularly at larger pore sizes, approximately 50 nm to 2 μm. This range reflects extraction of accessible organic material, including remaining gas molecules, bitumen, and kerogen derivatives, indicating where the larger amount of organic matter in shale is stored. An increase in porosity at smaller pore sizes, ~1-3 nm, was also present and could be indicative of extraction of organic material stored in the inter-particle spaces of clays. Additionally, a decrease in porosity after extraction for a sample was attributed to swelling of pores with solvent uptake. This occurred in a shale with high clay content and low thermal maturity. The extracted hydrocarbons were primarily paraffinic, although some breakdown of larger aromatic compounds was observed in toluene extractions. The amount of hydrocarbon extracted and an overall increase in porosity appeared to be primarily correlated with the clay percentage in the shale. This study complements fluid transport neutron

Geomechanical Anisotropy and Rock Fabric in Shales

NASA Astrophysics Data System (ADS)

Huffman, K. A.; Connolly, P.; Thornton, D. A.

2017-12-01

enables quantification of the impact that variations in rock fabric and grain interactions have on bulk mechanical rock behavior. When considered in terms of the stratigraphic framework of two different shale reservoirs it is found that silica distribution, clay content and orientation play a first order role in mechanical anisotropy.

Influence of herbicide structure, clay acidity, and humic acid coating on acetanilide herbicide adsorption on homoionic clays.

PubMed

Liu, Weiping; Gan, Jianying; Yates, Scott R

2002-07-03

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite was studied by coupling batch equilibration and FT-IR analysis. Adsorption decreased in the order metolachlor > acetochlor > alachlor > propachlor on Ca(2+)- or Mg(2+)-saturated clays and in the order metolachlor > alachlor > acetachlor > propachlor on Al(3+)- or Fe(3+)-saturated clays. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in bonding. For the same herbicide, adsorption of alachlor, acetachlor, and metolachlor on clay followed the order Ca(2+) approximately Mg(2+) < Al(3+) < or = Fe(3+), which coincided with the increasing acidity of homoionic clays. Adsorption of propachlor, however, showed an opposite dependence, suggesting a different governing interaction. In clay and humic acid mixtures, herbicide adsorption was less than that expected from independent additive adsorption by the individual constituents, and the deviation was dependent on the clay-to-humic acid ratio, with the greatest deviation consistently occurring at a 60:40 clay-to-humic acid ratio.

Zeta Potential Measurements on Three Clays from Turkey and Effects of Clays on Coal Flotation

PubMed

Hussain; Dem&idot;rc&idot;; özbayoğlu

1996-12-25

There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation.

Field Injection Test in the Host Rock nearby a Fault Zone - Stress Determination and Fault Hydraulic Diffusivity

NASA Astrophysics Data System (ADS)

Tsopela, A.; Guglielmi, Y.; Donze, F. V.; De Barros, L.; Henry, P.; Castilla, R.; Gout, C.

2017-12-01

Fluid injections associated with human activities are well known to induce perturbations in the ambient rock mass. In particular, the hydromechanical response of a nearby fault under an increase of the pore pressure is of great interest in permeability as well as seismicity related problems. We present a field injection experiment conducted in the host rock 4m away from a fault affecting Toarcian shales (Tournemire massif, France). The site was densely instrumented and during the test the pressure, displacements and seismicity were recorded in order to capture the hydro-mechanical response of the surrounding stimulated volume. A numerical model was used including the reactivated structure at the injection point interacting with a plane representing the main fault orientation. A number of calculations were performed in order to estimate the injection characteristics and the state of stress of the test. By making use of the recorded seismic events location an attempt is made to reproduce the spatio-temporal characteristics of the microseismicity cloud. We have introduced in the model heterogeneous frictional properties along the fault plane that result in flow and rupture channeling effects. Based on the spatio-temporal characteristics of these rupture events we attempt to estimate the resulting hydraulic properties of the fault according to the triggering front concept proposed by Shapiro et al. (2002). The effect of the frictional heterogeneities and the fault orientation on the resulting hydraulic diffusivity is discussed. We have so far observed in our model that by statistically taking into account the frictional heterogeneities in our analysis, the spatio-temporal characteristics of the rupture events and the recovered hydraulic properties of the fault are in a satisfying agreement. References: Shapiro, S. A., Rothert, E., Rath, V., & Rindschwentner, J. (2002). Characterization of fluid transport properties of reservoirs using induced microseismicity

The geochemistry of host arc volcanic rocks to the Co-O epithermal gold deposit, Eastern Mindanao, Philippines

NASA Astrophysics Data System (ADS)

Sonntag, Iris; Kerrich, Robert; Hagemann, Steffen G.

2011-12-01

Mindanao is the second largest island of the Philippines and is located in the southern part of the archipelago. It comprises the suture zone between the Eurasian and the Philippine plate, which is displayed in the Philippine Mobile Belt. Eastern Mindanao is part of the Philippine Mobile Belt and outcropping rocks are mainly Eocene to Pliocene in age related to episodes of arc volcanism alternating with sedimentation. New high-precision elemental analysis of the Oligocene magma series, hosting the Co-O epithermal Au deposit, which represents an arc segment in the central part of Eastern Mindanao, revealed dominantly calc-alkaline rocks ranging in composition between basalt and dacites. Major element trends (MgO vs. TiO2 and Fe2O3) are comparable to other magmas in Central and Eastern Mindanao as well as other SW Pacific Islands such as Borneo. Rare earth and trace element distribution patterns display typical island arc signatures highlighted by the conjunction of LILE-enrichment with troughs at Nb, Ta, and Ti. Ratios of Zr/Nb in basalts vary between 17 and 39, signifying a depleted subarc mantle wedge comparable to the range of MORB, and other Indonesian island arc basalts. In basalts, Nb/Ta and Zr/Sm ratios are 12-37 and 14-27 respectively indicative of deep melts of rutile-eclogite subducted slab, as well as fluids, infiltrating the mantle wedge source of basalts. Moderate large ion lithophile element contents and low Th/La and Th/Ce ratios suggest no significant slab-derived components such as sediment or crustal fragments. The comparatively low Ce and Yb values in basalts, but also andesites and dacites, are consistent with a thin arc crust related to an intraoceanic convergent margin setting. This is further supported by Nb contents in basalts that range between 1 and 3 ppm and are within the range of modern oceanic convergent margin basalts. The range of HREE fractionation signifies that basaltic melts separated at deeper levels of the subarc wedge, possibly

Clay-mediated reactions of HCN oligomers - The effect of the oxidation state of the clay

NASA Technical Reports Server (NTRS)

Ferris, J. P.; Alwis, K. W.; Edelson, E. H.; Mount, N.; Hagan, W. J., Jr.

1981-01-01

Montmorillonite clays which contain Fe(III) inhibit the oligomerization of aqueous solutions of HCN. The inhibitory effect is due to the rapid oxidation of diaminomaleonitrile, a key intermediate in HCN oligomerization, by the Fe(III) incorporated into the aluminosilicate lattice of the clay. The Fe(III) oxidizes diaminomaleonitrile to diiminosuccinonitrile, a compound which is rapidly hydrolyzed to HCN and oxalic acid derivatives. Diaminomaleonitrile is not oxidized when Fe(III) in the montmorillonite is reduced with hydrazine. The oxidation state of the clay is an important variable in experiments designed to simulate clay catalysis on the primitive earth.

Common clay and shale

USGS Publications Warehouse

Virta, R.L.

2003-01-01

Part of the 2002 industrial minerals review. The production, consumption, and price of shale and common clay in the U.S. during 2002 are discussed. The impact of EPA regulations on brick and structural clay product manufacturers is also outlined.

Lithium deposits hosted in intracontinental rhyolite calderas

NASA Astrophysics Data System (ADS)

Benson, T. R.; Coble, M. A.; Mahood, G. A.

2017-12-01

Lithium (Li) is classified as a technology-critical element due to the increasing demand for Li-ion batteries, which have a high power density and a relatively low cost that make them optimal for energy storage in mobile electronics, the electrical power grid, and hybrid and electric vehicles. Given that many projections for Li demand exceed current economic reserves and the market is dominated by Australia and Chile, discovery of new domestic Li resources will help diversify the supply chain and keep future technology costs down. Here we show that lake sediments preserved within intracontinental rhyolite calderas have the potential to host Li deposits on par with some of the largest Li brine deposits in the world. We compare Li concentrations of rhyolite magmas formed in a variety of tectonic settings using in situ SHRIMP-RG measurements of homogenized quartz-hosted melt inclusions. Rhyolite magmas that formed within thick, felsic continental crust (e.g., Yellowstone and Hideaway Park, United States) display moderate to extreme Li enrichment (1,500 - 9,000 ppm), whereas magmas formed in thin crust or crust comprised of accreted arc terranes (e.g., Pantelleria, Italy and High Rock, Nevada) contain Li concentrations less than 500 ppm. When the Li-enriched magmas erupt to form calderas, the cauldron depression serves as an ideal catchment within which meteoric water that leached Li from intracaldera ignimbrite, nearby outflow ignimbrite, and caldera-related lavas can accumulate. Additional Li is concentrated in the system through near-neutral, low-temperature hydrothermal fluids circulated along ring fractures as remnant magma solidifies and degasses. Li-bearing hectorite and illite clays form in this alteration zone, and when preserved in the geological record, can lead to a large Li deposit like the 2 Mt Kings Valley Li deposit in the McDermitt Caldera, Nevada. Because more than 100 large Cenozoic calderas occur in the western United States that formed on eruption

Mineral resource of the Month: Clay

USGS Publications Warehouse

Virta, Robert L.

2010-01-01

Clays were one of the first mineral commodities used by people. Clay pottery has been found in archeological sites that are 12,000 years old, and clay figurines have been found in sites that are even older.

Hydrogeologische Untersuchungen im oberflächennahen Opalinuston (Bohrloch Lausen, Schweiz)

NASA Astrophysics Data System (ADS)

Vogt, Tobias; Hekel, Uwe; Ebert, Andreas; Becker, Jens K.; Traber, Daniel; Giger, Silvio; Brod, Monika; Häring, Christian

2017-09-01

In Switzerland, the Opalinus Clay is being investigated in detail as a host rock for disposal of radioactive waste. To complement and improve existing data on near-surface decompaction effects, hydraulic-hydrochemical characterization of the Opalinus Clay from the weathering zone into the unweathered rock below was performed. For these investigations, one borehole of a borehole heat-exchanger field in Lausen (Canton Basel-Landschaft, Switzerland), which penetrates the near-surface Opalinus Clay, was completely cored. The hydraulic conductivity was determined by means of hydraulic tests in different depths and shows an decrease from 10-4 m/s at the very shallow weathered zone to 10-13 m/s starting at a depth of 28 m below the decompaction zone. In addition, different groundwater types could be identified. Moreover, the structural investigations indicate the end of the weathering zone at a depth of 18 m and that decompaction has no influence on hydraulic conductivity from 28 m onwards.

Characterization of Rare Earth Elements in in Clay Deposits Associated with Central Appalachian Coal Seams

NASA Astrophysics Data System (ADS)

Scott, M.; Verba, C.; Falcon, A.; Poston, J.; McKoy, M.

2017-12-01

Because of their multiple uses in clean energy technologies, rare earth elements (REE) are critical for national economic and energy security. With no current domestic source, supply remains a major concern for domestic security. Underclay - specifically the layer of stratum beneath a coal bed - is a potentially rich source of REE. This study focuses on the characterization and ion exchange recovery of REE from underclay samples from the Lower Freeport, Middle Kittanning, and Pittsburgh coal seams in West Virginia. Multimodal techniques provided quantitative assessments of REE-bearing mineral phases in select underclays and the influence of organic acid rock treatment on the recovery of REE from both exchangeable and crystalline mineral phases present. All samples are from extensively weathered horizons that contain abundant kaolinite and illite. Total REE concentrations range from 250-450 ppm and all samples have a HREE/LEEE ratio >20%. Rare earth element bearing minerals identified in the clay are monazite, xenotime, florencite, and crandallite. Our selective recovery approach is designed to isolate and recover REE through partial dissolution of the clay matrix and ion exchange rather than dissolution/recovery of phosphate or aluminosilicate bound REE. These results provide a better understanding of coal seam underclay, the affinity of REEs for specific ligands and colloids, and how the rock and ligands respond to different chemical treatments. These processes are important to the development and commercialization of efficient and cost effective methods to extract REE from domestic geologic deposits and recover into salable forms.

Separation of Diamagnetic and Paramagnetic Fabrics Reveals Strain Directions in Carbonate Rocks

NASA Astrophysics Data System (ADS)

Issachar, R.; Levi, T.; Marco, S.; Weinberger, R.

2018-03-01

We present a new procedure for separating magnetic fabrics in coccolith-bearing chalk samples, demonstrated in the case studies of three sites located within the Dead Sea Fault (DSF) plate boundary. The separation is achieved by combining measurements of room temperature and low-temperature anisotropy of magnetic susceptibility (RT-AMS and LT-AMS, respectively) with anisotropy of anhysteretic remanence magnetization (AARM). The LT-AMS, measured at 77 K, enhances the fabric of paramagnetic clay minerals. The AARM represents the fabric of ferromagnetic Fe oxides. By subtracting the paramagnetic and ferromagnetic fabrics from the RT-AMS, the diamagnetic fabric is separated. In the studied samples, we found that the ferromagnetic contribution to the bulk magnetic fabric is negligible and could be excluded from the subtraction procedure. Our analysis indicates that in chalks with a negligible ferromagnetic contribution, diamagnetic fabric predominates the rock bulk magnetic fabric, if the mean susceptibility is <-6 × 10-6 SI, whereas with a mean susceptibility >11 × 10-6 SI, paramagnetic fabric predominates. In the studied rocks, the paramagnetic clay minerals preserve the original depositional fabric, whereas the diamagnetic minerals show a tectonic fabric. We propose a mechanism by which coccolith rotation under tectonic strain contributes to the development of the diamagnetic fabric parallel to the shortening direction. We infer that the diamagnetic fabrics of the studied rocks indicate strain regime of approximately N-S horizontal shortening near strands of the DSF system. This suggests a deflection of the regional principal strain axes near the DSF. The diamagnetic fabric is more sensitive to tectonic strain than paramagnetic fabric in chalks and provides a valuable strain indicator near major faults.

Thermal conductivity anisotropy of metasedimentary and igneous rocks

NASA Astrophysics Data System (ADS)

Davis, Michael G.; Chapman, David S.; van Wagoner, Thomas M.; Armstrong, Phillip A.

2007-05-01

Thermal conductivity anisotropy was determined for three sets of metasedimentary and igneous rocks from central Utah, USA. Most conductivity measurements were made in transient mode with a half-space, line source instrument oriented in two orthogonal directions on a flat face cut perpendicular to bedding. One orientation of the probe yields thermal conductivity parallel to bedding (kpar) directly, the other orientation of the probe measures a product of conductivities parallel and perpendicular to bedding from which the perpendicular conductivity (kperp) is calculated. Some direct measurements of kpar and kperp were made on oriented cylindrical discs using a conventional divided bar device in steady state mode. Anisotropy is defined as kpar/kperp. Precambrian argillites from Big Cottonwood Canyon have anisotropy values from 0.8 to 2.1 with corresponding conductivity perpendicular to bedding of 2.0 to 6.2 W m-1 K-1. Anisotropy values for Price Canyon sedimentary samples are less than 1.2 with a mean of 1.04 although thermal conductivity perpendicular to bedding for the samples varied from 1.3 to 5.0 W m-1 K-1. The granitic rocks were found to be essentially isotropic with thermal conductivity perpendicular to bedding having a range of 2.2 to 3.2 W m-1 K-1 and a mean of 2.68 W m-1 K-1. The results confirm the observation by Deming [1994] that anisotropy is negligible for rocks having kperp greater than 4.0 W m-1 K-1 and generally increases for low conductivity metamorphic and clay-rich rocks. There is little evidence, however, for his suggestion that thermal conductivity anisotropy of all rocks increases systematically to about 2.5 for low thermal conductivity rocks.

Geochemistry of surface water in alpine catchments in central Colorado, USA: Resolving host-rock effects at different spatial scales

USGS Publications Warehouse

Wanty, R.B.; Verplanck, P.L.; San, Juan C.A.; Church, S.E.; Schmidt, T.S.; Fey, D.L.; deWitt, E.H.; Klein, T.L.

2009-01-01

The US Geological Survey is conducting a study of surface-water quality in the Rocky Mountains of central Colorado, an area of approximately 55,000 km2. Using new and existing geologic maps, the more than 200 rock formations represented in the area were arranged into 17 groups based on lithologic similarity. The dominant regional geologic feature affecting water quality in central Colorado is the Colorado mineral belt (CMB), a NE-trending zone hosting many polymetallic vein or replacement deposits, and porphyry Mo deposits, many of which have been mined historically. The influence of the CMB is seen in lower surface-water pH (<5), and higher concentrations of SO42 - (>100 mg/L) and chalcophile metals such as Cu (>10 ??g/L), Zn (>100 ??g/L), and Cd (>1 ??g/L) relative to surface water outside the CMB. Not all streams within the CMB have been affected by mineralization, as there are numerous catchments within the CMB that have no mineralization or alteration exposed at the surface. At the regional-scale, and away from sites affected by mineralization, hydrothermal alteration, or mining, the effects of lithology on water quality can be distinguished using geochemical reaction modeling and principal components analysis. At local scales (100 s of km2), effects of individual rock units on water chemistry are subtle but discernible, as shown by variations in concentrations of major lithophile elements or ratios between them. These results demonstrate the usefulness of regional geochemical sampling of surface waters and process-based interpretations incorporating geologic and geochemical understanding to establish geochemical baselines.

Comment on "Evaluation of X-ray diffraction methods for determining the crystal growth mechanisms of clay minerals in mudstones, shales and slates," by L. N. Warr and D. R. Peacor

USGS Publications Warehouse

Eberl, D.D.; Srodon, J.; Drits, V.A.

2003-01-01

A recent paper by Warr and Peacor (2002) suggested that our use of the Bertaut-Warren-Averbach technique (MudMaster computer program) for studying changes in crystallite thickness distributions (CTDs) of clay minerals during diagenesis and very low-grade metamorphism is not reliable because it is dependent on many variables which can not be fully controlled. Furthermore, the authors implied that the measured shapes of CTDs cannot be used with confidence to deduce crystal growth mechanisms and histories for clays, based on our CTD simulation approach (using the Galoper computer program). We disagree with both points, and show that the techniques are powerful, reliable and useful for studying clay mineral alteration in rocks. ?? 2003 Schweiz. Mineral. Petrogr. Ges.

Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

NASA Astrophysics Data System (ADS)

Niknezhad, Setareh

The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted

Clays and Clay Minerals and their environmental application in Food Technology

NASA Astrophysics Data System (ADS)

del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

2013-04-01

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References

Intercalated layered clay composites and their applications

NASA Astrophysics Data System (ADS)

Phukan, Anjali

Supported inorganic reagents are rapidly emerging as new and environmentally acceptable reagents and catalysts. The smectite group of layered clay minerals, such as, Montmorillonite, provides promising character for adsorption, catalytic activity, supports etc. for their large surface area, swelling behavior and ion exchange properties. Aromatic compounds intercalated in layered clays are useful in optical molecular devices. Clay is a unique material for adsorption of heavy metals and various toxic substances. Clay surfaces are known to be catalytically active due to their surface acidity. Acid activated clays possess much improved surface areas and acidities and have higher pore volumes so that can absorb large molecules in the pores. The exchangeable cations in clay minerals play a key role in controlling surface acidity and catalytic activity. Recently, optically active metal-complex-Montmorillonite composites are reported to be active in antiracemization purposes. In view of the above, a research work, relating to the preparation of different modified clay composites and their catalytic applications were carried out. The different aspects and results of the present work have been reported in four major chapters. Chapter I: This is an introductory chapter, which contains a review of the literature regarding clay-based materials. Clay minerals are phyllosilicates with layer structure. Montmorillonite, a member of smectite group of clay, is 2:1 phyllosilicate, where a layer is composed of an octahedral sheet sandwiched by two tetrahedral sheets. Such clay shows cation exchange capacity (CEC) and is expressed in milli-equivalents per 100 gm of dry clay. Clays can be modified by interaction with metal ion, metal complexes, metal cluster and organic cations for various applications. Clays are also modified by treating with acid followed by impregnation with metal salts or ions. Montmorillonite can intercalate suitable metal complexes in excess of CEC to form double

Macro-scale deformation behavior and characterization of deformation mechanisms below µm-scale in experimentally deformed Boom Clay by using the combination of triaxial compression, X-ray µ-CT imaging, DIC, BIB cross sectioning, and SEM

NASA Astrophysics Data System (ADS)

Oelker, Anne; Desbois, Guillaume; Urai, Janos L.; Bésuelle, Pierre; Viggiani, Gioacchino; Levasseur, Séverine

2017-04-01

Boom Clay is one formation being studied in Belgium as a potential host rock for deep geological disposal of radioactive waste. This poorly indurated clay presents in its natural state favorable properties against the migration of radionuclides: low permeability, low solute diffusion rates, good retention and sorption capacity for many radionuclides and good self-sealing capacity. During construction of disposal galleries, stress redistribution will lead to perturbation of the clay and the formation around galleries of the so-called "Excavation disturbed Zone" (EdZ). The study of deformation mechanisms and evolution of Boom Clay properties at macro but also micro scale allows to assess in a more mechanistic way the evolution of Boom Clay properties in this EdZ. In this work, we show microstructural investigations of Boom Clay deformed in undrained triaxial compression by linking conventional stress/strain curves with Digital Image Correlation (DIC) and scanning electron microscopy (SEM) imaging of broad-ion-beam (BIB) milled cross-sections to deduce deformation mechanisms based on microstructures at sub-micron resolution. Two specimens, collected in Mol (Belgium) at the European Underground Laboratories (URL) on HADES level, were analyzed: The major principal stress σ1 was applied parallel as well as perpendicular to the bedding direction with an initial mean normal effective stress of 4.5 MPa and an initial pore water pressure of 2.3 MPa, which are equal to the in-situ values. Linking the resulting DIC-derived maps of incremental strains with the corresponding stress/strain curve give not only information about the moment of the shear band development, but also on the way strain evolves within the specimen throughout the rest. Incremental DIC analysis of X-ray tomographic scans performed during loading tests give a time evolution of the strain field, and subsequently allow to detect strain localization which appears close to the stress peak. Regions with a

Treated and untreated rock dust: Quartz content and physical characterization.

PubMed

Soo, Jhy-Charm; Lee, Taekhee; Chisholm, William P; Farcas, Daniel; Schwegler-Berry, Diane; Harper, Martin

2016-11-01

Rock dusting is used to prevent secondary explosions in coal mines, but inhalation of rock dusts can be hazardous if the crystalline silica (e.g., quartz) content in the respirable fraction is high. The objective of this study is to assess the quartz content and physical characteristics of four selected rock dusts, consisting of limestone or marble in both treated (such as treatment with stearic acid or stearates) and untreated forms. Four selected rock dusts (an untreated and treated limestone and an untreated and treated marble) were aerosolized in an aerosol chamber. Respirable size-selective sampling was conducted along with particle size-segregated sampling using a Micro-Orifice Uniform Deposit Impactor. Fourier Transform Infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analyses were used to determine quartz mass and particle morphology, respectively. Quartz percentage in the respirable dust fraction of untreated and treated forms of the limestone dust was significantly higher than in bulk samples, but since the bulk percentage was low the enrichment factor would not have resulted in any major change to conclusions regarding the contribution of respirable rock dust to the overall airborne quartz concentration. The quartz percentage in the marble dust (untreated and treated) was very low and the respirable fractions showed no enrichment. The spectra from SEM-EDX analysis for all materials were predominantly from calcium carbonate, clay, and gypsum particles. No free quartz particles were observed. The four rock dusts used in this study are representative of those presented for use in rock dusting, but the conclusions may not be applicable to all available materials.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

PubMed

Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees

PubMed Central

Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms. PMID:26218593

Climatic Oscillations 10,000-155,000 yr B.P. at Owens Lake, California Reflected in Glacial Rock Flour Abundance and Lake Salinity in Core OL-92

USGS Publications Warehouse

Bischoff, J.L.; Menking, K.M.; Fitts, J.P.; Fitzpatrick, J.A.

1997-01-01

Chemical analyses of the acid-soluble and clay-size fractions of sediment samples (1500-yr resolution) reveal oscillations of lake salinity and of glacial advances in core OL-92 back to 155,000 yr B.P. Relatively saline conditions are indicated by the abundance of carbonate and smectite (both pedogenic and authigenic), reflected by Ca, Sr, and Mg in the acid-soluble suite, and by Cs2O, excess MgO, and LOI (loss on ignition) in the clay-size fraction. Rock flour produced during glacial advances is represented by the abundance of detrital plagioclase and biotite in the clay-size fraction, the ratio of which remains essentially constant over the entire time span. These phases are quantitatively represented by Na2O, TiO2, Ba, and Mn in the clay fraction. The rock-flour record indicates two major ice-advances during the penultimate glacial cycle corresponding to marine isotope stage (MIS) 6, no major advances during the last interglaciation (entire MIS 5), and three major advances during the last glacial cycle (MIS 2, 3, and 4). The ages of the latter three correspond rather well to 36Cl dates reported for Sierra Nevada moraines. The onset of the last interglaciation is shown by abrupt increases in authigenic CaCO3 and an abrupt decrease in rock flour, at about 118,000 yr B.P. according to our time scale. In contrast, the boundary appears to be gradual in the ??18O record in which the change from light to heavy values begins at about 140,000 yrs B.P. The exact position of the termination, therefore, may be proxy-dependent. Conditions of high carbonate and low rock flour prevailed during the entire period from 118,000 yr B.P. until the glacial advance at 53,000 yr B.P. signaled the end of this long interglaciation. ?? 1997 University of Washington.

Initiation of and distributed deformation at and around stylolite interfaces: Insights from detailed microstructural analysis

NASA Astrophysics Data System (ADS)

Ebner, M.; Piazolo, S.; Koehn, D.

2009-04-01

In the present contribution we investigate the microstructure of bedding parallel and bedding normal stylolites in carbonate rocks. We focused our study on micro-stylolites which represent an initial stage of this localised pressure solution process as stylolite roughness amplitude is a function of strain. We use electron backscatter diffraction analysis (EBSD) and orientation contrast imaging to address the following issues: (i) What causes the initiation of stylolite interfaces at a submicroscopic scale, (ii) is there distributed deformation around the stylolite interface and (iii) what is the role of the interface (residuum)? Our findings demonstrate that the characteristic stylolite teeth are initiated at a pre-existing heterogeneity in the host-rock. This quenched noise in carbonate rocks is typically composed of clay particles in the submicron scale. In addition, qtz-grains are present along especially pronounced stylolite peaks. The stylolite interface evolves with increasing strain from individual clay particles separated by grain-grain contacts of calcite along the interface to a continuous layer of clay and oxides. Thickness variation of the residuum along the interface is inferred to be strongly influenced by the pre-existing distribution of pinning particles that are more resistant to dissolution. Another important observation is that a shaped preferred orientation (SPO) exists in a halo around the stylolite. This SPO increases with proximity to the stylolite interface. Within this halo, crystal plastic deformation is expressed by subgrain formation with subgrain boundaries usually aligned parallel to shortening direction. Bedding normal (tectonic) stylolites which overprint already compacted beds i.e. with a pre-existing sedimentary SPO parallel to the bedding plane exhibit a SPO at a high angle to the sedimentary SPO. We conclude that stylolite roughness is primarily caused by pre-existing heterogeneities in the host-rock which are more resistant to

Study of thermo-hydro-mechanical processes at a potential site of an Indian nuclear waste repository

NASA Astrophysics Data System (ADS)

Maheshwar, Sachin; Verma, A. K.; Singh, T. N.; Bajpai, R. K.

2015-12-01

A detailed scientific study is required for the disposal of high-level radioactive wastes because they generate extremely high heat during their half-life period. Although, several methods have been proposed for the disposal of nuclear wastes, deep underground repository is considered to be a suitable option. In this paper, field investigation has been done near to Bhima basin of peninsular India. Detailed fracture analysis near the borehole shows very prominent maxima of fractures striking N55∘E coinciding with the trace of master basement cover metasediment fault. Physico-mechanical properties of rocks have been determined in the laboratory. The host rock chosen is granite and engineered barrier near the canister is proposed to be clay. A thermo-hydro-mechanical (THM) analysis has been done to study the effect of heat on deformations, stresses and pore-pressure variation in granite and clay barriers. For this purpose, finite difference method has been used. Suitable rheological models have been used to model elastic canister and elasto-plastic engineered barrier and host rock. It has been found that both temperature and stresses at any point in the rockmass is below the design criteria which are 100∘C for temperature and 0.2 for damage number.

Clays and clay minerals in Bikaner: Sources, environment pollution and management

NASA Astrophysics Data System (ADS)

Gayatri, Sharma; Anu, Sharma

2016-05-01

Environmental pollution can also be caused by minerals which include natural as well as human activities. Rapid urbanization, consumerist life style, anthropogenic deeds are increasing environmental pollution day by day. Fluctuation in our ecosystem or polluted environment leads to many diseases and shows adverse effects on living organisms. The main aim of this paper is to highlight the environmental pollution from clays and clay minerals and their mitigation..

Crude oil polycyclic aromatic hydrocarbons removal via clay-microbe-oil interactions: Effect of acid activated clay minerals.

PubMed

Ugochukwu, Uzochukwu C; Fialips, Claire I

2017-07-01

Acid treatment of clay minerals is known to modify their properties such as increase their surface area and surface acidity, making them suitable as catalysts in many chemical processes. However, the role of these surface properties during biodegradation processes of polycyclic aromatic hydrocarbons (PAHs) is only known for mild acid (0.5 M Hydrochloric acid) treated clays. Four different clay minerals were used for this study: a montmorillonite, a saponite, a palygorskite and a kaolinite. They were treated with 3 M hydrochloric acid to produce acid activated clay minerals. The role of the acid activated montmorillonite, saponite, palygorskite and kaolinite in comparison with the unmodified clay minerals in the removal of PAHs during biodegradation was investigated in microcosm experiments. The microcosm experiments contained micro-organisms, oil, and clays in aqueous medium with a hydrocarbon degrading microorganism community predominantly composed of Alcanivorax spp. Obtained results indicated that acid activated clays and unmodified kaolinite did not enhance the biodegradation of the PAHs whereas unmodified montmorillonite, palygorskite and saponite enhanced their biodegradation. In addition, unmodified palygorskite adsorbed the PAHs significantly due to its unique channel structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phengite-hosted LILE enrichment in eclogite and related rocks: Implications for fluid-mediated mass transfer in subduction zones and arc magma genesis

USGS Publications Warehouse

Sorensen, Sorena S.; Grossman, J.N.; Perfit, M.R.

1997-01-01

Geochemical differences between island arc basalts (LAB) and ocean-floor basalts (mid-ocean ridge basalts; MORB) suggest that the large-ion lithophile elements (LILE) K, Ba, Rb and Cs are probably mobilized in subduction zone fluids and melts. This study documents LILE enrichment of eclogite, amphibolite, and epidote ?? garnet blueschist tectonic blocks and related rocks from melanges of two subduction complexes. The samples are from six localities of the Franciscan Complex, California, and related terranes of Oregon and Baja California, and from the Samana Metamorphic Complex, Samana Peninsula, Dominican Republic. Most Franciscan blocks are MORB-like in their contents of rare earth elements (REE) and high field strength elements (HFSE); in contrast, most Samana blocks show an LAB signature of these elements. The whole-rock K2O contents of both groups range from 1 to 3 wt %; K, Ba, Rb, and Cs are all strongly intercorrelated. Many blocks display K/Ba similar to melasomatized transition zones and rinds at their outer margins. Some transition zones and rinds are enriched in LILE compared with host blocks; others are relatively depleted in these elements. Some LILE-rich blocks contain 'early' coarse-grained muscovite that is aligned in the foliation defined by coarse-grained omphacite or amphibole grains. Others display 'late' muscovite in veins and as a partial replacement of garnet; many contain both textural types. The muscovite is phengite that contains ???3??25-3??55 Si per 11 oxygens, and ???0??25-0??50 Mgper 11 oxygens. Lower-Si phengite has a significant paragonite component: Na per 11 oxygens ranges to ???0??12. Ba contents of phengite range to over 1 wt % (0??027 per 11 oxygens). Ba in phengite does not covary strongly with either Na or K. Ba contents of phengite increase from some blocks to their transition zones or rinds, or from blocks to their veins. Averaged KlBa ratios for phengite and host samples define an array which describes other subsamples of

The Science of Clay

ERIC Educational Resources Information Center

Warwick, Sharon

2005-01-01

Students' natural curiosity provides a rich opportunity for teachers to make meaningful scientific connections between art and ceramics that will enhance the understanding of both natural forces and scientific aspects at work in the creation of clay artworks. This article discusses the scientific areas of study related to clay, which include…

Comparative geology and geochemistry of sedimentary-rock-hosted (Carlin Type) gold deposits in the People's Republic of China and in Nevada, USA

USGS Publications Warehouse

Li, Zhiping; Peters, Stephen G.

1998-01-01

Sedimentary-rock-hosted (Carlin-type) gold deposits have been considered economically significant and geologically distinct since the early 1960's. This report consists of a nine-part text and an interactive database. This small database is to help Western companies get more information about these gold deposits in China, and to help geologists who are interested in world Carlin-type deposits conduct research on them. Because of their economic significance and geological distinctiveness, these deposits have caught the interest of economic geologists all over the world since the early 1960's. Similar deposits have been discovered in China, Australia, Dominican Republic, Spain, and Russia besides Nevada. Perhaps most significant are the 165 Carlin-type gold deposits that were found in southwest China during the past 15 years. Of these, at least 19 deposits have proven to be of substantial tonnage, making China the second leading country to exploit such deposits. With the increasing interest in Chinese Carlin-type gold deposits, some western companies and geologists desire to get more information about these Chinese deposits. This seems to have been very difficult because the literature was in Chinese. It is estimated that several hundred scientific publications (including papers, books, and technical reports) have been published. This database of Chinese Carlin-type Gold deposits is built on the documentation published during the most recent 10 years and includes six subjects, which consist of 165 records and 30 fields. A new Proterozoic-age sedimentary-rock-hosted gold deposit in northeastern P.R. China also is described. Note that for the old version 1.1 on the CD-ROM, the latitude and longitude locations of the mineral occurrences have been estimated from sketch maps and journal articles and are not intended for digital analysis. One of the improvements in this version 1.2 is the accuracy of geographic data. Version 1.3 updates to the database and includes maps

Radiolysis of alanine adsorbed in a clay mineral

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

2013-07-03

Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role againstmore » external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.« less

Preparation and Characterization of Nano Gold Supported over Montmorillonite Clays

NASA Astrophysics Data System (ADS)

Suraja, P. V.; Binitha, N. N.; Yaakob, Z.; Silija, P. P.

2011-02-01

The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl4·3H2O by deposition-precipitation (DP) methods. However, it is difficult to prepare nanoscale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. There is no need of increasing the pH of the solution to reduce the Au3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-VIS Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method.

Role of Clay Minerals in Long-Distance Transport of Landslides in Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Watkins, J.; Ehlmann, B. L.; Yin, A.

2014-12-01

Long-runout (> 50 km) subaerial landslides are rare on Earth, but are common features episodically shaping Mars' Valles Marineris (VM) trough system over the past 3.5 billion years. They display two end-member morphologies: a thick-skinned inner zone, characterized by fault-bounded, rotated blocks near their source region, and a thin-skinned, exceptionally long-runout outer zone, characterized by thin sheets spreading over 10s of km across the trough floor. Four decades of studies on the latter have resulted in two main competing hypotheses to explain their long-distance transport: (1) movement of landslides over layers of trapped air or soft materials containing ice or snow, enabling basal lubrication, and (2) fluidization of landslide materials with or without the presence of water and volatiles. To address this issue, we examine the mineralogic composition of landslides across VM using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) near-infrared spectral data analysis coupled with detailed geologic mapping and morphometric analysis of satellite images. Our survey reveals a general correlation between transport distance, significant lateral spreading, and the presence of hydrated silicates among VM landslides. Given that smectite clay absorbs water into its layered crystal structure and can reduce the friction coefficient by a factor of three v. that of dry rocks, these results suggest that hydrated silicates played a decisive role in facilitating long-runout landslide transport in VM. We propose that, concurrent with downslope failure and sliding of broken trough-wall rock, frontal landslide masses overrode and entrained hydrated-silicate-bearing trough-floor deposits, lubricating the basal sliding zones and permitting the landslide outer zones to spread laterally while moving forward over the low-friction surface. The key participation of hydrated silicates in episodic, sustained landslide activity throughout the canyon implies that clay minerals

Thermal Conductivity Anisotropy of Metasedimentary and Igneous Rocks

NASA Astrophysics Data System (ADS)

Davis, M. G.; Chapman, D. S.; van Wagoner, T. M.; Armstrong, P. A.

2005-12-01

Thermal conductivity anisotropy was determined for two sets of rocks: a series of sandstones, mudstones, and limey shales of Cretaceous age from Price Canyon, Utah, and metasedimentary argillites and quartzites of Precambrian age from the Big Cottonwood Formation in north central Utah. Additional anisotropy measurements were made on granitic rocks from two Tertiary plutons in Little Cottonwood Canyon, north central Utah. Most conductivity measurements were made in transient mode with a half-space, line-source instrument oriented in two orthogonal directions on a flat face cut perpendicular to bedding. One orientation of the probe yields thermal conductivity parallel to bedding (kmax) directly, the other orientation of the probe measures a product of conductivities parallel and perpendicular to bedding from which the perpendicular conductivity (kperp) is calculated. Some direct measurements of kmax and kperp were made on oriented cylindrical discs using a conventional divided bar device in steady-state mode. Anisotropy is defined as kmax/kperp. The Precambrian argillites from Big Cottonwood Canyon have anisotropy values from 0.8 to 2.1 with corresponding conductivity perpendicular to bedding of 2.0 to 6.2 W m-1 K-1. Anisotropy values for the Price Canyon samples are less than 1.2 with a mean of 1.04 although thermal conductivity perpendicular to bedding for the samples varied from 1.3 to 5.0 W m-1 K-1. The granitic rocks were found to be essentially isotropic with thermal conductivity perpendicular to bedding having a range of 2.2 to 3.2 W m-1 K-1 and a mean of 2.68 W m-1 K-1. The results confirm the observation by Deming (1994) that anisotropy is negligible for rocks having kperp greater than 4.0 W m-1 K-1 and generally increases for low conductivity metamorphic and clay-rich rocks. There is little evidence, however, for his suggestion that thermal conductivity anisotropy of all rocks increases systematically to about 2.5 for low thermal conductivity rocks.

Characterization and origin of spongillite-hosting sediment from João Pinheiro, Minas Gerais, Brazil

NASA Astrophysics Data System (ADS)

Almeida, A. C. S.; Varajão, A. F. D. C.; Gomes, N. S.; Varajão, C. A. C.; Volkmer-Ribeiro, C.

2010-03-01

Spongillite from João Pinheiro, Minas Gerais, Brazil is mainly known for its use in brick production and in the refractory industry. Very few studies have focused on its geological context. Spongillite-rich deposits occur in shallow ponds on a karstic planation surface developed on rocks of the Neoproterozoic São Francisco Supergroup. Cenozoic siliciclastic sediments are related to this surface. A field study of these deposits and analysis of multispectral images showed a SE-NW preferential drainage system at SE, suggesting that Mesozoic Areado Group sandstones were the source area of the spongillite-hosting sediments. Mineralogical and textural characterization by optical microscopic analysis, X-ray diffraction (XRD), differential and gravimetric thermal analysis (DTA-GTA), infrared spectroscopy (IR) and scanning electron microscopy (SEM) of seven open-pit spongillite-rich deposits (Avião, Carvoeiro, Vânio, Preguiça, Divisa, Severino, Feijão) showed a sedimentological similarity between the deposits. They are lens-shaped and are characterized at the bottom by sand facies, in the middle by spicules-rich muddy-sand facies and at the top by organic matter-rich muddy-sand facies. Petrographically, the spongillite-hosting sediments and the siliclastic sediments of the Areado Group show detrital phases with similar mineralogical and textural features, such as the presence of well-sorted quartz grains and surface features of abrasion typical of aeolian reworking that occurred in the depositional environment in which the sandstones of the Areado Group were formed. Detrital heavy minerals, such as staurolite, zircon, tourmaline, and clay minerals, such as kaolinite, low amounts of illite, scarce chlorite and mixed-layer chlorite/smectite and illite/smectite occur in the spongillite-hosting sediments and in sandstones from the Areado Group. In both formations, staurolite has similar chemical composition. These mineralogical and textural features show that the

Petrographic and geochemical data for Cenozoic volcanic rocks of the Bodie Hills, California and Nevada

USGS Publications Warehouse

du Bray, Edward A.; John, David A.; Box, Stephen E.; Vikre, Peter G.; Fleck, Robert J.; Cousens, Brian L.

2013-04-23

Petrographic and geochemical data for Cenozoic volcanic rocks of the Bodie Hills, California and Nevada // // This report presents petrographic and geochemical data for samples collected during investigations of Tertiary volcanism in the Bodie Hills of California and Nevada. Igneous rocks in the area are principally 15–6 Ma subduction-related volcanic rocks of the Bodie Hills volcanic field but also include 3.9–0.1 Ma rocks of the bimodal, post-subduction Aurora volcanic field. Limited petrographic results for local basement rocks, including Mesozoic granitoid rocks and their metamorphic host rocks, are also included in the compilation. The petrographic data include visual estimates of phenocryst abundances as well as other diagnostic petrographic criteria. The geochemical data include whole-rock major oxide and trace element data, as well as limited whole-rock isotopic data.

What Makes a Natural Clay Antibacterial?

PubMed Central

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-Peterson, Amisha T.

2011-01-01

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (<200 nm), illite-smectite and reduced iron phases. The role of clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals. PMID:21413758

REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes

USGS Publications Warehouse

Foley, Nora K.; Ayuso, Robert A.; Simandl, G.J.; Neetz, M.

2015-01-01

The Southeastern United States contains numerous anorogenic, or A-type, granites, which constitute promising source rocks for REE-enriched ion adsorption clay deposits due to their inherently high concentrations of REE. These granites have undergone a long history of chemical weathering, resulting in thick granite-derived regoliths, akin to those of South China, which supply virtually all heavy REE and Y, and a significant portion of light REE to global markets. Detailed comparisons of granite regolith profiles formed on the Stewartsville and Striped Rock plutons, and the Robertson River batholith (Virginia) indicate that REE are mobile and can attain grades comparable to those of deposits currently mined in China. A REE-enriched parent, either A-type or I-type (highly fractionated igneous type) granite, is thought to be critical for generating the high concentrations of REE in regolith profiles. One prominent feature we recognize in many granites and mineralized regoliths is the tetrad behaviour displayed in REE chondrite-normalized patterns. Tetrad patterns in granite and regolith result from processes that promote the redistribution, enrichment, and fractionation of REE, such as late- to post- magmatic alteration of granite and silicate hydrolysis in the regolith. Thus, REE patterns showing tetrad effects may be a key for discriminating highly prospective source rocks and regoliths with potential for REE ion adsorption clay deposits.

Comparison of the bulk geochemical features and thermal reactivity of kerogens from Mol (Boom Clay), Bure (Callovo-Oxfordian argillite) and Tournemire (Toarcian shales) underground research laboratories.

PubMed

Deniau, I; Devol-Brown, I; Derenne, S; Behar, F; Largeau, C

2008-01-25

Deep argillaceous formations are potential repositories for the long-term disposal of nuclear waste because of their low permeability and high sorption capacity with respect to radioelements and heavy metals. Such sedimentary rocks contain organic matter, mostly macromolecular and insoluble (kerogen). Upon temperature elevation related to high-level long-lived radioactive waste disposal, the kerogen may release significant quantities of gaseous and liquid effluents, especially oxygen-containing ones, which may influence the ability of the clay to retain radionuclides. The aim of the present study is to assess the global geochemical features and the thermal reactivity of the kerogens isolated from samples collected in the Bure and Tournemire sites, France (Callovo-Oxfordian Clay and Toarcian Shales, respectively) and to draw comparisons with data previously obtained for the Mol site, Belgium (Boom Clay). The study is based on a combination of elemental, spectroscopic (FTIR, solid state (13)C NMR) and pyrolytic (Rock-Eval pyrolysis, Curie point pyrolysis-gas chromatography/mass spectrometry) analyses. Different levels of maturity and resulting differences in the relative abundance of oxygen-containing groups were thus observed for the three kerogens. This is linked with differences in their ability to generate CO(2) and various oxygen-containing, low molecular weight, water-soluble compounds under thermal stress, decreasing from Mol to Bure and to Tournemire.

Hydrothermal modification of host rock geochemistry within Mo-Cu porphyry deposits in the Galway Granite, western Ireland

NASA Astrophysics Data System (ADS)

Tolometti, Gavin; McCarthy, Will

2016-04-01

Hydrothermal alteration of host rock is a process inherent to the formation of porphyry deposits and the required geochemical modification of these rocks is regularly used to indicate proximity to an economic target. The study involves examining the changes in major, minor and trace elements to understand how the quartz vein structures have influenced the chemistry within the Murvey Granite that forms part of the 380-425Ma Galway Granite Complex in western Ireland. Molybdenite mineralisation within the Galway Granite Complex occurred in close association with protracted magmatism at 423Ma, 410Ma, 407Ma, 397Ma and 383Ma and this continues to be of interest to active exploration. The aim of the project is to characterize hydrothermal alteration associated with Mo-Cu mineralisation and identify geochemical indicators that can guide future exploration work. The Murvey Granite intrudes metagabbros and gneiss that form part of the Connemara Metamorphic complex. The intrusion is composed of albite-rich pink granite, garnetiferous granite and phenocrytic orthoclase granite. Minor doleritic dykes post-date the Murvey Granite, found commonly along its margins. Field mapping shows that the granite is truncated to the east by a regional NW-SE fault and that several small subparallel structures host Mo-Cu bearing quartz veins. Petrographic observations show heavily sericitized feldspars and plagioclase and biotite which have undergone kaolinization and chloritisation. Chalcopyrite minerals are fine grained, heavily fractured found crystallized along the margins of the feldspars and 2mm pyrite crystals. Molybdenite are also seen along the margins of the feldspars, crystallized whilst the Murvey Granite cooled. Field and petrographic observations indicate that mineralisation is structurally controlled by NW-SE faults from the selected mineralization zones and conjugate NE-SW cross cutting the Murvey Granite. Both fault orientations exhibit quartz and disseminated molybdenite

Burnt clay magnetic properties and palaeointensity determination

NASA Astrophysics Data System (ADS)

Avramova, Mariya; Lesigyarski, Deyan

2014-05-01

Burnt clay structures found in situ are the most valuable materials for archaeomagnetic studies. From these materials the full geomagnetic field vector described by inclination, declination and intensity can be retrieved. The reliability of the obtained directional results is related to the precision of samples orientation and the accuracy of characteristic remanence determination. Palaeointensity evaluations depend on much more complex factors - stability of carried remanent magnetization, grain-size distribution of magnetic particles and mineralogical transformations during heating. In the last decades many efforts have been made to shed light over the reasons for the bad success rate of palaeointensity experiments. Nevertheless, sometimes the explanation of the bad archaeointensity results with the magnetic properties of the studied materials is quite unsatisfactory. In order to show how difficult is to apply a priory strict criteria for the suitability of a given collection of archaeomagnetic materials, artificial samples formed from four different baked clays are examined. Two of the examined clay types were taken from clay deposits from different parts of Bulgaria and two clays were taken from ancient archaeological baked clay structures from the Central part of Bulgaria and the Black sea coast, respectively. The samples formed from these clays were repeatedly heated in known magnetic field to 700oC. Different analyses were performed to obtain information about the mineralogical content and magnetic properties of the samples. The obtained results point that all clays reached stable magnetic mineralogy after the repeated heating to 700oC, the main magnetic mineral is of titano/magnetite type and the magnetic particles are predominantly with pseudo single domain grain sizes. In spite that, the magnetic properies of the studied clays seem to be very similar, reliable palaeointensity results were obtained only from the clays coming from clay deposits. The

Do Hf isotopes in magmatic zircons represent those of their host rocks?

NASA Astrophysics Data System (ADS)

Wang, Di; Wang, Xiao-Lei; Cai, Yue; Goldstein, Steven L.; Yang, Tao

2018-04-01

Lu-Hf isotopic system in zircon is a powerful and widely used geochemical tracer in studying petrogenesis of magmatic rocks and crustal evolution, assuming that zircon Hf isotopes can represent initial Hf isotopes of their parental whole rock. However, this assumption may not always be valid. Disequilibrium partial melting of continental crust would preferentially melt out non-zircon minerals with high time-integrated Lu/Hf ratios and generate partial melts with Hf isotope compositions that are more radiogenic than those of its magma source. Dissolution experiments (with hotplate, bomb and sintering procedures) of zircon-bearing samples demonstrate this disequilibrium effect where partial dissolution yielded variable and more radiogenic Hf isotope compositions than fully dissolved samples. A case study from the Neoproterozoic Jiuling batholith in southern China shows that about half of the investigated samples show decoupled Hf isotopes between zircons and the bulk rocks. This decoupling could reflect complex and prolonged magmatic processes, such as crustal assimilation, magma mixing, and disequilibrium melting, which are consistent with the wide temperature spectrum from ∼630 °C to ∼900 °C by Ti-in-zircon thermometer. We suggest that magmatic zircons may only record the Hf isotopic composition of their surrounding melt during crystallization and it is uncertain whether their Hf isotopic compositions can represent the primary Hf isotopic compositions of the bulk magmas. In this regard, using zircon Hf isotopic compositions to trace crustal evolution may be biased since most of these could be originally from disequilibrium partial melts.

Reactive Transport Modeling and Changes in Porosity at Reactive Interfaces in a HLW repository in Clay

NASA Astrophysics Data System (ADS)

Samper, J.; Mon, A.; Montenegro, L.; Naves, A.; Fernández, J.

2016-12-01

High-level radioactive waste disposal in a deep geological repository is based on a multibarrier concept which combines natural barriers such as the geological formation and artificial barriers such as metallic containers, bentonite and concrete buffers and sealing materials. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyperalkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyperalkaline plume at the concrete-clay interface. Here we present a nonisothermal reactive transport model of the long-term interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. This problem involves large pH changes with a hyperalkaline high-pH plume, complex mineral dissolution/precipitation patterns, cation exchange reactions and proton surface complexation. These reactions lead to large changes in porosity which can even lead to pore clogging. Model results show that magnetite, the main corrosion product, precipitates and reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The zones affected by pore clogging at the canister-bentonite, bentonite-concrete and concrete-clay interfaces at 1 Ma are equal to 10, 25 and 25 mm thick, respectively. The results of our simulations share many of the features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Narrow alteration zones; and 2) Pore clogging at the canister-bentonite, bentonite-concrete and concrete-clay

Microtomographic quantification of hydraulic clay mineral displacement effects during a CO2 sequestration experiment with saline aquifer sandstone.

PubMed

Sell, Kathleen; Enzmann, Frieder; Kersten, Michael; Spangenberg, Erik

2013-01-02

We combined a noninvasive tomographic imaging technique with an invasive open-system core-flooding experiment and compared the results of the pre- and postflooded states of an experimental sandstone core sample from an ongoing field trial for carbon dioxide geosequestration. For the experiment, a rock core sample of 80 mL volume was taken from the 629 m Stuttgart Formation storage domain of a saline sandstone aquifer at the CCS research pilot plant Ketzin, Germany. Supercritical carbon dioxide and synthetical brine were injected under in situ reservoir p/T-conditions at an average flow rate of 0.1 mL/min for 256 h. X-ray computed microtomographic imaging was carried out before and after the core-flooding experiment at a spatial voxel resolution of 27 μm. No significant changes in microstructure were found at the tomographic imaging resolution including porosity and pore size distribution, except of an increase of depositional heterogeneous distribution of clay minerals in the pores. The digitized rock data were used as direct real microstructure input to the GeoDict software package, to simulate Navier-Stokes flow by a lattice Boltzmann equation solver. This procedure yielded 3D pressure and flow velocity fields, and revealed that the migration of clay particles decreased the permeability tensor probably due to clogging of pore openings.

Use of spectral gamma ray as a lithology guide for fault rocks: A case study from the Wenchuan Earthquake Fault Scientific Drilling project Borehole 4 (WFSD-4).

PubMed

Amara Konaté, Ahmed; Pan, Heping; Ma, Huolin; Qin, Zhen; Guo, Bo; Yevenyo Ziggah, Yao; Kounga, Claude Ernest Moussounda; Khan, Nasir; Tounkara, Fodé

2017-10-01

The main purpose of the Wenchuan Earthquake Fault Scientific drilling project (WFSD) was to produce an in-depth borehole into the Yingxiu-Beichuan (YBF) and Anxian-Guanxian faults in order to gain a much better understanding of the physical and chemical properties as well as the mechanical faulting involved. Five boreholes, namely WFSD-1, WFSD-2, WFSD-3P, WFSD-3 and WFSD-4, were drilled during the project entirety. This study, therefore, presents first-hand WFSD-4 data on the lithology (original rocks) and fault rocks that have been obtained from the WFSD project. In an attempt to determine the physical properties and the clay minerals of the lithology and fault rocks, this study analyzed the spectral gamma ray logs (Total gamma ray, Potassium, Thorium and Uranium) recorded in WFSD-4 borehole on the Northern segment of the YBF. The obtained results are presented as cross-plots and statistical multi log analysis. Both lithology and fault rocks show a variability of spectral gamma ray (SGR) logs responses and clay minerals. This study has shown the capabilities of the SGR logs for well-logging of earthquake faults and proves that SGR logs together with others logs in combination with drill hole core description is a useful method of lithology and fault rocks characterization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uranium mineralization in fluorine-enriched volcanic rocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burt, D.M.; Sheridan, M.F.; Bikun, J.

1980-09-01

Several uranium and other lithophile element deposits are located within or adjacent to small middle to late Cenozoic, fluorine-rich rhyolitic dome complexes. Examples studied include Spor Mountain, Utah (Be-U-F), the Honeycomb Hills, Utah (Be-U), the Wah Wah Mountains, Utah (U-F), and the Black Range-Sierra Cuchillo, New Mexico (Sn-Be-W-F). The formation of these and similar deposits begins with the emplacement of a rhyolitic magma, enriched in lithophile metals and complexing fluorine, that rises to a shallow crustal level, where its roof zone may become further enriched in volatiles and the ore elements. During initial explosive volcanic activity, aprons of lithicrich tuffsmore » are erupted around the vents. These early pyroclastic deposits commonly host the mineralization, due to their initial enrichment in the lithophile elements, their permeability, and the reactivity of their foreign lithic inclusions (particularly carbonate rocks). The pyroclastics are capped and preserved by thick topaz rhyolite domes and flows that can serve as a source of heat and of additional quantities of ore elements. Devitrification, vapor-phase crystallization, or fumarolic alteration may free the ore elements from the glassy matrix and place them in a form readily leached by percolating meteoric waters. Heat from the rhyolitic sheets drives such waters through the system, generally into and up the vents and out through the early tuffs. Secondary alteration zones (K-feldspar, sericite, silica, clays, fluorite, carbonate, and zeolites) and economic mineral concentrations may form in response to this low temperature (less than 200 C) circulation. After cooling, meteoric water continues to migrate through the system, modifying the distribution and concentration of the ore elements (especially uranium).« less

Understanding Potassium Isotope Fractionation During Authigenic Clay Formation in Pore-fluid Systems: Implications for the δ41K of Seawater

NASA Astrophysics Data System (ADS)

Santiago Ramos, D. P.; Higgins, J. A.

2015-12-01

Improvements in analytical precision on the latest generation multi-collector inductively coupled plasma mass spectrometers (MC-ICP-MS) have revealed a ~2‰ range in the ratios of stable potassium isotopes (41K/39K) in terrestrial materials (Morgan et al., in prep). Preliminary measurements of δ41K values indicate that seawater and silicate rocks are isotopically distinct reservoirs, with seawater having a δ41K value that is ~0.5‰ heavier than the silicate average (-0.5‰; Morgan et al., in prep). The heavy δ41K character of seawater might be related to 1) an isotopically enriched input flux (rivers and high-temperature hydrothermal reactions); or 2) a 41K-depleted sink associated with authigenic clay formation during low-temperature alteration of volcanic rocks. Here we present measurements of the δ41K values of pore-fluids from ODP site 1052 in order to constrain potassium isotope fractionation during secondary clay formation. We find that δ41K values and K concentrations both decline systematically with depth. Results from 1-D diffusion-advection-reaction modeling of potassium concentrations and isotopic compositions indicate that fractionation of K isotopes during diffusion (Bourg et al., 2010) can explain all of the change in δ41K values of the pore-fluid with depth. Although the size of the K sink at site 1052 is a trivial fraction of the global K sink in clay minerals, our results suggest that diffusive fractionation of K isotopes in shallow pore-fluids may be, in part, responsible for the elevated δ41K value of seawater.

Mineralogical and geochemical studies on the Central Seruyan Pb-Zn deposits in Central Kalimantan, Indonesia

NASA Astrophysics Data System (ADS)

Choi, Y.; Lee, I.; Choi, B.; KIM, Y.; Moon, I.

2017-12-01

The Central Seruyan Pb-Zn deposit is located in Seruyan, Central Kalimantan Province in Indonesia. This deposit has been developed since last year and is still being investigated. The Pb-Zn deposit consists of two formations, Pinoh and Kuayan formation. The former is a metamorphic unit hosting schist, phyllite and gneiss, and the latter is a pyroclastic and volcanic unit includes intermediate volcanic rocks such as dacite, tuff and breccia. Most host rocks of the deposit is composed of the silicified porphyritic dacite and silicified phyllite and covered by silicified tuff. The joints and fractures within the wall rock has E-W trends. The Seruyan Pb-Zn deposit is considered as hydrothermal breccia type.In this study, we observe ore minerals and host rocks to understand the genesis of the Pb-Zn deposit with geochemical data. Pyrite, chalcopyrite, sphalerite and galena are major ore minerals and covellite and bornite are also observed as minor sulfide minerals. These ore minerals, except pyrite, usually occur within quartz or calcite veins indicating the influence of hydrothermal fluid. In the host rocks, dacite, has the altered minerals like sericite, chlorite, epidote and some clay minerals of hydrothermal origin. All minerals occur as massive form. Only some pyrites have an euhedral form. Small amount of Au, Ag and Mo are detected in major ore minerals in the EPMA (electron probe X-ray microanalyzer) analyses.

Gas Hydrate Estimation Using Rock Physics Modeling and Seismic Inversion

NASA Astrophysics Data System (ADS)

Dai, J.; Dutta, N.; Xu, H.

2006-05-01

ABSTRACT We conducted a theoretical study of the effects of gas hydrate saturation on the acoustic properties (P- and S- wave velocities, and bulk density) of host rocks, using wireline log data from the Mallik wells in the Mackenzie Delta in Northern Canada. We evaluated a number of gas hydrate rock physics models that correspond to different rock textures. Our study shows that, among the existing rock physics models, the one that treats gas hydrate as part of the solid matrix best fits the measured data. This model was also tested on gas hydrate hole 995B of ODP leg 164 drilling at Blake Ridge, which shows adequate match. Based on the understanding of rock models of gas hydrates and properties of shallow sediments, we define a procedure that quantifies gas hydrate using rock physics modeling and seismic inversion. The method allows us to estimate gas hydrate directly from seismic information only. This paper will show examples of gas hydrates quantification from both 1D profile and 3D volume in the deepwater of Gulf of Mexico.

Fire clay

USGS Publications Warehouse

Virta, R.L.

2004-01-01

Seven companies mined fire clay in four states during 2003. From 1984 to 1992, production declined to 383 kt (422,000 st) from a high of 1.04 Mt (1.14 million st) as markets for clay-based refractories declined. Since 1992, production levels have been erratic, ranging from 383 kt (422,000 st) in 1992 and 2001 to 583 kt (642,000 st) in 1995. Production in 2003, based on preliminary data, was estimated to be around 450 kt (496,000 st) with a value of about $10.5 million. This was about the same as in 2002. Missouri remained the leading producer state, followed by South Carolina, Ohio and California.

Examination and Manipulation of Clay Aggregates - Initial Inquiry

DTIC Science & Technology

2011-06-06

and the first conclusions in the examination and testing of clay aggregates composed of montmorillonite clay and a polysaccharide (xanthan gum, also...and the first conclusions in the examination and testing of clay aggregates composed of montmorillonite clay and a polysaccharide (xanthan gum, also...PSU and the X-gum content from 0% to 10% of the mineral content of the clay (by weight). Montmorillonite was used in all the suspensions prepared

Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

PubMed

Moran, Anthony R; Hettiarachchi, Hiroshan

2011-07-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

PubMed Central

Moran, Anthony R.; Hettiarachchi, Hiroshan

2011-01-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

Use of a Dual-Structure Constitutive Model for Predicting the Long-Term Behavior of an Expansive Clay Buffer in a Nuclear Waste Repository

DOE PAGES

Vilarrasa, Víctor; Rutqvist, Jonny; Blanco Martin, Laura; ...

2015-12-31

hosted in a clay rock formation. The thermo-hydro-mechanical results of the dual-structure model were compared with those of the standard single-structure BBM. The main difference between the simulation results from the two models is that the dual-structure model predicted a time to fully saturate the expansive clay barrier on the order of thousands of years, whereas the standard single-structure BBM yielded a time on the order of tens of years. These examples show that a dual-structure model, such as the one presented here, is necessary to properly model the thermo-hydro-mechanical behavior of expansive soils.« less

Observations on burrowing rates and comments on host specificity in the endangered mussel Lampsilis higginsi

USGS Publications Warehouse

Sylvester, J.R.; Holland, L.E.; Kamer, T.K.

1984-01-01

In preliminary laboratory studies, the endangered mussel Lampsilis higginsi was unable to burrow into rocky substrates, but did burrow into substrates comprised of silt, clay, sand, and/or pebble-gravel. Burrowing times were shortest in silt and longest in pebble-gravel. As judged by longevity of glochidial infection, walleye (Stizostedion vitreum) and largemouth bass (Micropterus salmoides) may be suitable hosts for the parasitic stage. When glochidia were placed in water without host fish, half had died after 48 hours, and all had died after 72 hours. (DBO).

PERMEABILITY CHANGES IN CRYSTALLINE ROCKS DUE TO TEMPERATURE: EFFECTS OF MINERAL ASSEMBLAGE.

USGS Publications Warehouse

Morrow, C.A.; Moore, Diane E.; Byerlee, J.D.; ,

1985-01-01

The change in permeability with time of granite, quartzite, anorthosite and gabbro was measured while these rocks were subjected to a temperature gradient. Permeability reductions of up to two orders of magnitude were observed, with the greatest reactions occurring in the quartzite. These changes are thought to be caused by dissolution of minerals at high temperatures, and redeposition of the dissolved material at lower temperatures. Quartz appears to be an important mineral in this self-sealing process. If very low permeability is desired around a nuclear waste repository in crystalline rocks, then a quartz-rich rock may be the most appropriate host.

Thermo-hydro-mechanical coupling in long-term sedimentary rock response

NASA Astrophysics Data System (ADS)

Makhnenko, R. Y.; Podladchikov, Y.

2017-12-01

Storage of nuclear waste or CO2 affects the state of stress and pore pressure in the subsurface and may induce large thermal gradients in the rock formations. In general, the associated coupled thermo-hydro-mechanical effect on long-term rock deformation and fluid flow have to be studied. Principles behind mathematical models for poroviscoelastic response are reviewed, and poroviscous model parameter, the bulk viscosity, is included in the constitutive equations. Time-dependent response (creep) of fluid-filled sedimentary rocks is experimentally quantified at isotropic stress states. Three poroelastic parameters are measured by drained, undrained, and unjacketed geomechanical tests for quartz-rich Berea sandstone, calcite-rich Apulian limestone, and clay-rich Jurassic shale. The bulk viscosity is calculated from the measurements of pore pressure growth under undrained conditions, which requires time scales 104 s. The bulk viscosity is reported to be on the order of 1015 Pa•s for the sandstone, limestone, and shale. It is found to be decreasing with the increase of pore pressure despite corresponding decrease in the effective stress. Additionally, increase of temperature (from 24 ºC to 40 ºC) enhances creep, where the most pronounced effect is reported for the shale with bulk viscosity decrease by a factor of 3. Viscous compaction of fluid-filled porous media allows a generation of a special type of fluid flow instability that leads to formation of high-porosity, high-permeability domains that are able to self-propagate upwards due to interplay between buoyancy and viscous resistance of the deforming porous matrix. This instability is known as "porosity wave" and its formation is possible under conditions applicable to deep CO2 storage in reservoirs and explains creation of high-porosity channels and chimneys. The reported experiments show that the formation of high-permeability pathways is most likely to occur in low-permeable clay-rich materials (caprock

Experimental validation of Swy-2 clay standard's PHREEQC model

NASA Astrophysics Data System (ADS)

Szabó, Zsuzsanna; Hegyfalvi, Csaba; Freiler, Ágnes; Udvardi, Beatrix; Kónya, Péter; Székely, Edit; Falus, György

2017-04-01

One of the challenges of the present century is to limit the greenhouse gas emissions for the mitigation of climate change which is possible for example by a transitional technology, CCS (Carbon Capture and Storage) and, among others, by the increase of nuclear proportion in the energy mix. Clay minerals are considered to be responsible for the low permeability and sealing capacity of caprocks sealing off stored CO2 and they are also the main constituents of bentonite in high level radioactive waste disposal facilities. The understanding of clay behaviour in these deep geological environments is possible through laboratory batch experiments of well-known standards and coupled geochemical models. Such experimentally validated models are scarce even though they allow deriving more precise long-term predictions of mineral reactions and rock and bentonite degradation underground and, therefore, ensuring the safety of the above technologies and increase their public acceptance. This ongoing work aims to create a kinetic geochemical model of Na-montmorillonite standard Swy-2 in the widely used PHREEQC code, supported by solution and mineral composition results from batch experiments. Several four days experiments have been carried out in 1:35 rock:water ratio at atmospheric conditions, and with inert and CO2 supercritical phase at 100 bar and 80 ⁰C relevant for the potential Hungarian CO2 reservoir complex. Solution samples have been taken during and after experiments and their compositions were measured by ICP-OES. The treated solid phase has been analysed by XRD and ATR-FTIR and compared to in-parallel measured references (dried Swy-2). Kinetic geochemical modelling of the experimental conditions has been performed by PHREEQC version 3 using equations and kinetic rate parameters from the USGS report of Palandri and Kharaka (2004). The visualization of experimental and numerous modelling results has been automatized by R. Experiments and models show very fast

Multiscale properties of unconventional reservoir rocks

NASA Astrophysics Data System (ADS)

Woodruff, W. F.

A multidisciplinary study of unconventional reservoir rocks is presented, providing the theory, forward modeling and Bayesian inverse modeling approaches, and laboratory protocols to characterize clay-rich, low porosity and permeability shales and mudstones within an anisotropic framework. Several physical models characterizing oil and gas shales are developed across multiple length scales, ranging from microscale phenomena, e.g. the effect of the cation exchange capacity of reactive clay mineral surfaces on water adsorption isotherms, and the effects of infinitesimal porosity compaction on elastic and electrical properties, to meso-scale phenomena, e.g. the role of mineral foliations, tortuosity of conduction pathways and the effects of organic matter (kerogen and hydrocarbon fractions) on complex conductivity and their connections to intrinsic electrical anisotropy, as well as the macro-scale electrical and elastic properties including formulations for the complex conductivity tensor and undrained stiffness tensor within the context of effective stress and poroelasticity. Detailed laboratory protocols are described for sample preparation and measurement of these properties using spectral induced polarization (SIP) and ultrasonics for the anisotropic characterization of shales for both unjacketed samples under benchtop conditions and jacketed samples under differential loading. An ongoing study of the effects of kerogen maturation through hydrous pyrolysis on the complex conductivity is also provided in review. Experimental results are catalogued and presented for various unconventional formations in North America including the Haynesville, Bakken, and Woodford shales.

Preparation and properties of recycled HDPE/clay hybrids

Treesearch

Yong Lei; Qinglin Wu; Craig M. Clemons

2007-01-01

Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could...

Did the Kiruna iron ores form as a result of a metasomatic or igneous process? New U-Pb and Nd data for the iron oxide apatite ores and their host rocks in the Norrbotten region of northern Sweden

NASA Astrophysics Data System (ADS)

Westhues, A.; Hanchar, J. M.; Whitehouse, M. J.; Fisher, C. M.

2012-12-01

A number of iron deposits near Kiruna in the Norrbotten region of northern Sweden are of the iron oxide apatite (IOA) type of deposits; also referred to as Kiruna-type deposits. They are commonly considered a subgroup or end-member of iron oxide copper gold (IOCG) deposits, containing no economic grades of copper or gold. Both IOCG and IOA deposits are characterized by abundant low-Ti Fe oxides, an enrichment in REE, and intense sodium and potassium wall-rock alteration adjacent to the ores. Deposits of these types are of a great economic importance, not only for iron, but also for other elements such as rare earth elements (REE) or uranium. Kiruna, the type locality of the IOA type of mineral deposits, is the focus of this study. Despite a century-long mining history and 2500 Mt of iron ore produced in the region to date (with grades of 30 to 70 wt.% Fe), the genesis of these deposits is poorly understood: theories of a magmatic vs. a hydrothermal or metasomatic origin have been debated, and the timing of mineralization of the ores in the Norbotten region has never been directly dated. The results anticipated from this study will provide a better understanding of the nature of the IOA type of mineral deposits and their relation to IOCG deposits such as Olympic Dam in Australia. An array of geochemical methods is used in order to gain insights on the emplacement history of the host rocks, their subsequent alteration, and the ore genesis of these deposits. This includes in situ U/Pb geochronology of zircon, monazite, and titanite to constrain the timing between host rock emplacement, alteration and mineralization. Isotopic data from whole rocks and in situ at mineral scale will provide constraints on the involvement of hydrothermal fluids and their possible sources, as well as on the sources of Fe, U, and the REE. Newly obtained Sm-Nd isotopic data points to distinct source differences between host rocks, ore and alteration related samples. Preliminary in situ U

Iodide uptake by negatively charged clay interlayers?

PubMed

Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

2015-09-01

Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Clays and other minerals in prebiotic processes

NASA Technical Reports Server (NTRS)

Paecht-Horowitz, M.

1984-01-01

Clays and other minerals have been investigated in context with prebiotic processes, mainly in polymerization of amino acids. It was found that peptides adsorbed on the clay, prior to polymerization, influence the reaction. The ratio between the amount of the peptides adsorbed and that of the clay is important for the yield as well as for the degrees of polymerization obtained. Adsorption prior to reaction produces a certain order in the aggregates of the clay particles which might induce better reaction results. Excess of added peptides disturbs this order and causes lesser degrees of polymerization. In addition to adsorption, clays are also able to occlude between their layers substances out of the environment, up to very high concentrations.

Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

2003-01-01

A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

Clay-Bacteria Systems and Biofilm Production

NASA Astrophysics Data System (ADS)

Steiner, J.; Alimova, A.; Katz, A.; Steiner, N.; Rudolph, E.; Gottlieb, P.

2007-12-01

Soil clots and the aerosol transport of bacteria and spores are promoted by the formation of biofilms (bacteria cells in an extracellular polymeric matrix). Biofilms protect microorganisms by promoting adhesion to both organic and inorganic surfaces. Time series experiments on bacteria-clay suspensions demonstrate that biofilm growth is catalyzed by the presence of hectorite in minimal growth media for the studied species: Gram negatives (Pseudomonas syringae and Escherichia coli,) and Gram positives (Staphylococcus aureus and Bacillus subtilis). Soil organisms (P. syringae, B. subtilis) and organisms found in the human population (E. coli, S. aureus) are both used to demonstrate the general applicability of clay involvement. Fluorescent images of the biofilms are acquired by staining with propidium iodide, a component of the BacLightTM Live/Dead bacterial viability staining kit (Molecular Probes, Eugene, OR). The evolving polysaccharide-rich biofilm reacts with the clay interlayer site causing a complex substitution of the two-water hectorite interlayer with polysaccharide. The result is often a three-peak composite of the (001) x-ray diffraction maxima resulting from polysaccharide-expanded clays and an organic-driven contraction of a subset of the clays in the reaction medium. X-ray diffractograms reveal that the expanded set creates a broad maximum with clay subsets at 1.84 nm and 1.41 nm interlayer spacings as approximated by a least squares double Lorentzian fit, and a smaller shoulder at larger 2q, deriving from a contraction of the interlayer spacing. Washing with chlorox removes organic material from the contracted clay and creates a 1-water hectorite single peak in place of the double peak. The clay response can be used as an indirect indicator of biofilm in an environmental system.

On the frictional (in) stability of clay-bearing faults

NASA Astrophysics Data System (ADS)

Violay, M.; Orellana, F.; Scuderi, M. M.; Collettini, C.

2016-12-01

Opalinus clay (OPA) is shale rock studied under the context of deep geological disposal by The Mont Terri Laboratory research program in Switzerland. Despite its favorable hydro-mechanical properties, the presence of a large tectonic fault system intersecting the rock formation arises questions over the long-term safety performance of a nuclear waste repository, in terms of possible leakages and the possibility of earthquakes triggered by fault instability. To study the frictional stability of OPA, we have performed velocity steps (1-300 μm/s) and slide-hold-slide tests (1-10000 s) on simulated gouge and intact samples - sheared parallel and perpendicular to foliation - at different normal stresses (4 - 30 MPa). To understand the deformation mechanisms, we have analyzed the microstructures of the sheared samples trough optical and SE microscopy. Results reported peak and steady state friction values ranging from 0.21 to 0.52 and from 0.14 to 0.39 respectively. Consistently, samples with well-developed layering showed lower friction values than gouge samples even though they have the same mineralogical composition. At all normal stresses, velocity dependence tests on gouge showed a velocity strengthening regime, whereas, intact samples developed both velocity-strengthening and velocity-weakening regimes. Finally, we have recorded near zero healing values for both intact and powdered samples at different normal stress. However, a complex evolution from negative to positive frictional healing rate, with an inflexion holding time of 300 s, has been observed. In conclusion, our data suggests that both the velocity strengthening regime and the near zero healing for the simulated gouge, are consistent with aseismic creep. We have also reported the possibility of unstable sliding outside the fault core accompanied by low capacity of contact regeneration, and low capacity to sustain future stress drops compared to evidence showed by experiments on simulated gouge. Moreover

Clay-Enriched Silk Biomaterials for Bone Formation

PubMed Central

Mieszawska, Aneta J.; Llamas, Jabier Gallego; Vaiana, Christopher A.; Kadakia, Madhavi P.; Naik, Rajesh R.; Kaplan, David L.

2011-01-01

The formation of silk protein/clay composite biomaterials for bone tissue formation is described. Silk fibroin serves as an organic scaffolding material offering mechanical stability suitable for bone specific uses. Clay montmorillonite (Cloisite ® Na+) and sodium silicate are sources of osteoinductive silica-rich inorganic species, analogous to bioactive bioglass-like bone repair biomaterial systems. Different clay particle-silk composite biomaterial films were compared to silk films doped with sodium silicate as controls for support of human bone marrow derived mesenchymal stem cells (hMSCs) in osteogenic culture. The cells adhered and proliferated on the silk/clay composites over two weeks. Quantitative real-time RT-PCR analysis revealed increased transcript levels for alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col I) osteogenic markers in the cells cultured on the silk/clay films in comparison to the controls. Early evidence for bone formation based on collagen deposition at the cell-biomaterial interface was also found, with more collagen observed for the silk films with higher contents of clay particles. The data suggest that the silk/clay composite systems may be useful for further study toward bone regenerative needs. PMID:21549864

Structure and clay mineralogy: borehole images, log interpretation and sample analyses at Site C0002 Nankai Trough accretionary prism

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Schleicher, Anja

2015-04-01

Our research focused on the characterization of fracture and fault structures from the deep Nankai Trough accretionary prism in Japan. Logging Data and cuttings samples from the two most recent International Ocean Discovery Program (IODP) Expeditions 338 and 348 of the NanTroSEIZE project were analyzed by Logging While Drilling (LWD) oriented images, geophysical logs and clay mineralogy. Both expeditions took place at Site C0002, but whereas Hole C0002F (Expedition 338) was drilled down to 2004.5 mbsf, Hole C0002N and C0002P (Expedition 348) reached a depth of 2325.5 mbsf and 3058.8 mbsf respectively. The structural interpretation of borehole imaging data illustrates the deformation within the fractured and faulted sections of the accretionary prism. All drill holes show distinct areas of intense fracturing and faulting within a very clay-dominated lithology. Here, smectite and illite are the most common clay minerals, but the properties and the role they may play in influencing the fractures, faults and folds in the accretionary prism is still not well understood. When comparing clay mineralogy and fracture/fault areas in hole C0002F (Expedition 338), a trend in the abundance of illite and smectite, and in particular the swelling behavior of smectite is recognizable. In general, the log data provided a good correlation with the actual mineralogy and the relative abundance of clay. Ongoing postcruise preliminary research on hole C0002 N and C0002P (Expedition 348) should confirm these results. The relationship between fracture and fault structures and the changes in clay mineralogy could be explained by the deformation of specific areas with different compaction features, fluid-rock interaction processes, but could also be related to beginning diagenetic processes related to depth. Our results show the integration of logging data and cutting sample analyses as a valuable tool for characterization of petrophysical and mineralogical changes of the structures of the

Soil clay content underlies prion infection odds

USGS Publications Warehouse

David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

2011-01-01

Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

Soil clay content underlies prion infection odds

PubMed Central

David Walter, W.; Walsh, Daniel P.; Farnsworth, Matthew L.; Winkelman, Dana L.; Miller, Michael W.

2011-01-01

Environmental factors—especially soil properties—have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. PMID:21326232

Soil clay content underlies prion infection odds.

PubMed

David Walter, W; Walsh, Daniel P; Farnsworth, Matthew L; Winkelman, Dana L; Miller, Michael W

2011-02-15

Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings.

Interphase vs confinement in starch-clay bionanocomposites.

PubMed

Coativy, Gildas; Chevigny, Chloé; Rolland-Sabaté, Agnès; Leroy, Eric; Lourdin, Denis

2015-03-06

Starch-clay bionanocomposites containing 1-10% of natural montmorillonite were elaborated by melt processing in the presence of water. A complex macromolecular dynamics behavior was observed: depending on the clay content, an increase of the glass transition temperature and/or the presence of two overlapped α relaxation peaks were detected. Thanks to a model allowing the prediction of the average interparticle distance, and its comparison with the average size of starch macromolecules, it was possible to associate these phenomena to different populations of macromolecules. In particular, it seems that for high clay content (10%), the slowdown of segmental relaxation due to confinement of the starch macromolecules between the clay tactoïds is the predominant phenomenon. While for lower clay contents (3-5%), a significant modification of chain relaxation seems to occur, due to the formation of an interphase by the starch macromolecules in the vicinity of clay nanoparticles coexisting with the bulk polymer. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sulfur mass-independent fractionation in subsurface fracture waters indicates a long-standing sulfur cycle in Precambrian rocks.

PubMed

Li, L; Wing, B A; Bui, T H; McDermott, J M; Slater, G F; Wei, S; Lacrampe-Couloume, G; Lollar, B Sherwood

2016-10-27

The discovery of hydrogen-rich waters preserved below the Earth's surface in Precambrian rocks worldwide expands our understanding of the habitability of the terrestrial subsurface. Many deep microbial ecosystems in these waters survive by coupling hydrogen oxidation to sulfate reduction. Hydrogen originates from water-rock reactions including serpentinization and radiolytic decomposition of water induced by decay of radioactive elements in the host rocks. The origin of dissolved sulfate, however, remains unknown. Here we report, from anoxic saline fracture waters ∼2.4 km below surface in the Canadian Shield, a sulfur mass-independent fractionation signal in dissolved sulfate. We demonstrate that this sulfate most likely originates from oxidation of sulfide minerals in the Archaean host rocks through the action of dissolved oxidants (for example, HO · and H 2 O 2 ) themselves derived from radiolysis of water, thereby providing a coherent long-term mechanism capable of supplying both an essential electron donor (H 2 ) and a complementary acceptor (sulfate) for the deep biosphere.

Sulfur mass-independent fractionation in subsurface fracture waters indicates a long-standing sulfur cycle in Precambrian rocks

PubMed Central

Li, L.; Wing, B. A.; Bui, T. H.; McDermott, J. M.; Slater, G. F.; Wei, S.; Lacrampe-Couloume, G.; Lollar, B. Sherwood

2016-01-01

The discovery of hydrogen-rich waters preserved below the Earth's surface in Precambrian rocks worldwide expands our understanding of the habitability of the terrestrial subsurface. Many deep microbial ecosystems in these waters survive by coupling hydrogen oxidation to sulfate reduction. Hydrogen originates from water–rock reactions including serpentinization and radiolytic decomposition of water induced by decay of radioactive elements in the host rocks. The origin of dissolved sulfate, however, remains unknown. Here we report, from anoxic saline fracture waters ∼2.4 km below surface in the Canadian Shield, a sulfur mass-independent fractionation signal in dissolved sulfate. We demonstrate that this sulfate most likely originates from oxidation of sulfide minerals in the Archaean host rocks through the action of dissolved oxidants (for example, HO· and H2O2) themselves derived from radiolysis of water, thereby providing a coherent long-term mechanism capable of supplying both an essential electron donor (H2) and a complementary acceptor (sulfate) for the deep biosphere. PMID:27807346

Compositional controls on early diagenetic pathways in fine-grained sedimentary rocks: Implications for predicting unconventional reservoir attributes of mudstones

USGS Publications Warehouse

Keller, Margaret A.; Macquaker, Joe H.S.; Taylor, Kevin G.; Polya, David

2014-01-01

Diagenesis significantly impacts mudstone lithofacies. Processes operating to control diagenetic pathways in mudstones are poorly known compared to analogous processes occurring in other sedimentary rocks. Selected organic-carbon-rich mudstones, from the Kimmeridge Clay and Monterey Formations, have been investigated to determine how varying starting compositions influence diagenesis.The sampled Kimmeridge Clay Formation mudstones are organized into thin homogenous beds, composed mainly of siliciclastic detritus, with some constituents derived from water-column production (e.g., coccoliths, S-depleted type-II kerogen, as much as 52.6% total organic carbon [TOC]) and others from diagenesis (e.g., pyrite, carbonate, and kaolinite). The sampled Monterey Formation mudstones are organized into thin beds that exhibit pelleted wavy lamination, and are predominantly composed of production-derived components including diatoms, coccoliths, and foraminifera, in addition to type-IIS kerogen (as much as 16.5% TOC), and apatite and silica cements.During early burial of the studied Kimmeridge Clay Formation mudstones, the availability of detrital Fe(III) and reactive clay minerals caused carbonate- and silicate-buffering reactions to operate effectively and the pore waters to be Fe(II) rich. These conditions led to pyrite, iron-poor carbonates, and kaolinite cements precipitating, preserved organic carbon being S-depleted, and sweet hydrocarbons being generated. In contrast, during the diagenesis of the sampled Monterey Formation mudstones, sulfide oxidation, coupled with opal dissolution and the reduced availability of both Fe(III) and reactive siliciclastic detritus, meant that the pore waters were poorly buffered and locally acidic. These conditions resulted in local carbonate dissolution, apatite and silica cements precipitation, natural kerogen sulfurization, and sour hydrocarbons generation.Differences in mud composition at deposition significantly influence subsequent

Sampling the oxidative weathering products and the potentially acidic permafrost on Mars

NASA Technical Reports Server (NTRS)

Burns, Roger G.

1988-01-01

Large areas of Mars' surface are covered by oxidative weathering products containing ferric and sulfate ions having analogies to terrestrial gossans derived from sulfide mineralization associated with iron-rich basalts. Chemical weathering of such massive and disseminated pyrrhotite-pentlandite assemblages and host basaltic rocks in the Martian environment could have produced metastable gossaniferous phases (limonite containing poorly crystalline hydrated ferric sulfates and oxyhydroxides, clay silicates and opal). Underlying groundwater, now permafrost on Mars, may still be acidic due to incomplete buffering reactions by wall-rock alteration of unfractured host rock. Such acidic solutions stabilize temperature-sensitive complex ions and sols which flocculate to colloidal precipitates at elevated temperatures. Sampling procedures of Martian regolith will need to be designed bearing in mind that the frozen permafrost may be corrosive and be stabilizing unique complex ions and sols of Fe, Al, Mg, Ni and other minor elements.

Petrography and geochemistry of precambrian rocks from GT-2 and EE-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laughlin, A.W.; Eddy, A.

1977-08-01

During the drilling of GT-2 and EE-1, 27 cores totaling about 35 m were collected from the Precambrian section. Samples of each different lithology in each core were taken for petrographic and whole-rock major- and trace-element analyses. Whole-rock analyses are now completed on 37 samples. From these data four major Precambrian units were identified at the Fenton Hill site. Geophysical logs and cuttings were used to extrapolate between cores. The most abundant rock type is an extremely variable gneissic unit comprising about 75% of the rock penetrated. This rock is strongly foliated and may range compositionally from syenogranitic to tonaliticmore » over a few centimeters. The bulk of the unit falls within the monzogranite field. Interlayered with the gneiss is a ferrohastingsite-biotite schist which compositionally resembles a basaltic andesite. A fault contact between the schist and gneiss was observed in one core. Intrusive into this metamorphic complex are two igneous rocks. A leucocratic monzogranite occurs as at least two 15-m-thick dikes, and a biotite-granodiorite body was intercepted by 338 m of drill hole. Both rocks are unfoliated and equigranular. The biotite granodiorite is very homogeneous and is characterized by high modal contents of biotite and sphene and by high K/sub 2/O, TiO/sub 2/, and P/sub 2/O/sub 5/ contents. Although all of the cores examined show fractures, most of these are tightly sealed or healed. Calcite is the most abundant fracture filling mineral, but epidote, quartz, chlorite, clays or sulfides have also been observed. The degree of alteration of the essential minerals normally increases as these fractures are approached. The homogeneity of the biotite granodiorite at the bottom of GT-2 and the high degree of fracture filling ensure an ideal setting for the Hot Dry Rock Experiment.« less

[Mechanisms of removing red tide organisms by organo-clays].

PubMed

Cao, Xi-Hua; Song, Xiu-Xian; Yu, Zhi-Ming; Wang, Kui

2006-08-01

We tested the influence of the preparation conditions of the quaternary ammonium compounds (QACs) modified clays on their capacities to remove red tide organisms, then discussed the mechanisms of the organo-clays removing red tide organisms. Hexadecyltrimethylammonium (HDTMA) improved the capacity of clays to flocculate red tide algae, and the HDTMA in metastable state enhanced the toxicity of the clay complexes to algae. The capacities of the organo-clays correlated with the toxicity and the adsorbed amount of the QACs used in clays modification, but as the incubation time was prolonged the stability of the organo-clays was improved and the algal removal efficiencies of the clay complexes decreased. When the adsorbed HDTMA was arranged in different clays in which the spatial resistance was different, there was more HDTMA in metastable state in the three-layer montmorillonite. Because of the homo-ion effect the bivalent or trivalent metal ions induced more HDTMA in metastable state and the corresponding organo-clays had high capacities to remove red tide organisms. When the reaction temperature was 60 degrees C the adsorbed HDTMA was easily arranged on cation exchange sites, if the temperature rose or fell the metastable HDTMA would increase so that the capacity of the clays was improved.

Scattering from Rock and Rock Outcrops

DTIC Science & Technology

2015-09-30

Scattering from Rock and Rock Outcrops Derek R. Olson The Pennsylvania State University Applied Research Laboratory, P.O. Box 30 State...In terms of target detection and classification, scattering from exposed rock on the seafloor, (i.e., individual rocks and rock outcrops) presents...levels, and other statistical measures of acoustic scattering from rocks and rock outcrops is therefore critical. Unfortunately (and curiously

Prediction of brittleness based on anisotropic rock physics model for kerogen-rich shale

NASA Astrophysics Data System (ADS)

Qian, Ke-Ran; He, Zhi-Liang; Chen, Ye-Quan; Liu, Xi-Wu; Li, Xiang-Yang

2017-12-01

The construction of a shale rock physics model and the selection of an appropriate brittleness index ( BI) are two significant steps that can influence the accuracy of brittleness prediction. On one hand, the existing models of kerogen-rich shale are controversial, so a reasonable rock physics model needs to be built. On the other hand, several types of equations already exist for predicting the BI whose feasibility needs to be carefully considered. This study constructed a kerogen-rich rock physics model by performing the selfconsistent approximation and the differential effective medium theory to model intercoupled clay and kerogen mixtures. The feasibility of our model was confirmed by comparison with classical models, showing better accuracy. Templates were constructed based on our model to link physical properties and the BI. Different equations for the BI had different sensitivities, making them suitable for different types of formations. Equations based on Young's Modulus were sensitive to variations in lithology, while those using Lame's Coefficients were sensitive to porosity and pore fluids. Physical information must be considered to improve brittleness prediction.

Compressibility characteristics of Sabak Bernam Marine Clay

NASA Astrophysics Data System (ADS)

Lat, D. C.; Ali, N.; Jais, I. B. M.; Baharom, B.; Yunus, N. Z. M.; Salleh, S. M.; Azmi, N. A. C.

2018-04-01

This study is carried out to determine the geotechnical properties and compressibility characteristics of marine clay collected at Sabak Bernam. The compressibility characteristics of this soil are determined from 1-D consolidation test and verified by existing correlations by other researchers. No literature has been found on the compressibility characteristics of Sabak Bernam Marine Clay. It is important to carry out this study since this type of marine clay covers large coastal area of west coast Malaysia. This type of marine clay was found on the main road connecting Klang to Perak and the road keeps experiencing undulation and uneven settlement which jeopardise the safety of the road users. The soil is indicated in the Generalised Soil Map of Peninsular Malaysia as a CLAY with alluvial soil on recent marine and riverine alluvium. Based on the British Standard Soil Classification and Plasticity Chart, the soil is classified as a CLAY with very high plasticity (CV). Results from laboratory test on physical properties and compressibility parameters show that Sabak Bernam Marine Clay (SBMC) is highly compressible, has low permeability and poor drainage characteristics. The compressibility parameters obtained for SBMC is in a good agreement with other researchers in the same field.

Characterizing Excavation Damaged Zone and Stability of Pressurized Lined Rock Caverns for Underground Compressed Air Energy Storage

NASA Astrophysics Data System (ADS)

Kim, Hyung-Mok; Rutqvist, Jonny; Jeong, Ju-Hwan; Choi, Byung-Hee; Ryu, Dong-Woo; Song, Won-Kyong

2013-09-01

In this paper, we investigate the influence of the excavation damaged zone (EDZ) on the geomechanical performance of compressed air energy storage (CAES) in lined rock caverns. We conducted a detailed characterization of the EDZ in rock caverns that have been excavated for a Korean pilot test program on CAES in (concrete) lined rock caverns at shallow depth. The EDZ was characterized by measurements of P- and S-wave velocities and permeability across the EDZ and into undisturbed host rock. Moreover, we constructed an in situ concrete lining model and conducted permeability measurements in boreholes penetrating the concrete, through the EDZ and into the undisturbed host rock. Using the site-specific conditions and the results of the EDZ characterization, we carried out a model simulation to investigate the influence of the EDZ on the CAES performance, in particular related to geomechanical responses and stability. We used a modeling approach including coupled thermodynamic multiphase flow and geomechanics, which was proven to be useful in previous generic CAES studies. Our modeling results showed that the potential for inducing tensile fractures and air leakage through the concrete lining could be substantially reduced if the EDZ around the cavern could be minimized. Moreover, the results showed that the most favorable design for reducing the potential for tensile failure in the lining would be a relatively compliant concrete lining with a tight inner seal, and a relatively stiff (uncompliant) host rock with a minimized EDZ. Because EDZ compliance depends on its compressibility (or modulus) and thickness, care should be taken during drill and blast operations to minimize the damage to the cavern walls.

Fracture behavior of polypropylene/clay nanocomposites.

PubMed

Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

2006-12-01

Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

Effects of Space Weathering on Lunar Rocks: Scanning Electron Microscope Petrography

NASA Technical Reports Server (NTRS)

Wentworth, Susan J.; Keller, Lindsay P.; McKay, David S.

1998-01-01

Lunar rocks that have undergone direct exposure to the space weathering environment at the surface of the Moon commonly have patinas on their surfaces. Patinas are characterized by visible darkening and other changes in spectral properties of rocks. They form as a result of bombardment by micrometeorites, solar wind, and solar flares. Processes of space weathering and patina production have clearly been significant in the formation and history of the lunar regolith. It is very likely that other planetary bodies without atmospheres have undergone similar alteration processes; therefore, it is critical to determine the relationship between patinas and their host rocks in view of future robotic and remote-sensing missions to the Moon and other planetary bodies.

Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

PubMed

Kang, Il-Mo; Roh, Ki-Min

2013-01-01

The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

Multi-element analysis of emeralds and associated rocks by k(o) neutron activation analysis

PubMed

Acharya; Mondal; Burte; Nair; Reddy; Reddy; Reddy; Manohar

2000-12-01

Multi-element analysis was carried out in natural emeralds, their associated rocks and one sample of beryl obtained from Rajasthan, India. The concentrations of 21 elements were assayed by Instrumental Neutron Activation Analysis using the k0 method (k0 INAA method) and high-resolution gamma ray spectrometry. The data reveal the segregation of some elements from associated (trapped and host) rocks to the mineral beryl forming the gemstones. A reference rock standard of the US Geological Survey (USGS BCR-1) was also analysed as a control of the method.

Multifaceted role of clay minerals in pharmaceuticals

PubMed Central

Khurana, Inderpreet Singh; Kaur, Satvinder; Kaur, Harpreet; Khurana, Rajneet Kaur

2015-01-01

The desirable physical and physiochemical properties of clay minerals have led them to play a substantial role in pharmaceutical formulations. Clay minerals like kaolin, smectite and palygorskite-sepiolite are among the world's most valuable industrial minerals and of considerable importance. The elemental features of clay minerals which caused them to be used in pharmaceutical formulations are high specific area, sorption capacity, favorable rheological properties, chemical inertness, swelling capacity, reactivity to acids and inconsiderable toxicity. Of course, these are highly cost effectual. This special report on clay minerals provides a bird's eye view of the chemical composition and structure of these minerals and their influence on the release properties of active medicinal agents. Endeavor has been made to rope in myriad applications depicting the wide acceptability of these clay minerals. PMID:28031881

Single clay sheets inside electrospun polymer nanofibers

NASA Astrophysics Data System (ADS)

Sun, Zhaohui

2005-03-01

Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

Geoelectric characteristics of portions of the Raha fault zone and surrounding rocks, Jabal As Silsilah Quadrangle, Kingdom of Saudi Arabia

USGS Publications Warehouse

Zablocki, Charles J.; Hajnour, M.O.

1987-01-01

Telluric-electric and auto-magnetotelluric measurements obtained in and around the Raha fault zone in the Buqaya area indicate that it dips steeply to the southwest. Large contrasts in the electrical properties of Qarnayn and Maraghan metasedimentary rocks located on either side of the fault are characteristic of the rocks within the fault zone. However, no large electrical contrasts were detected along several segments of a southern branch of the main fault in the Shiaila area, indicating that the rocks on either side of the fault are of similar composition. Extremely low resistivity readings in the Buqaya and Shiaila areas are associated with fracturing and clay-bearing gouge that accompany known shear zones. The locations of several shallow plutons have been inferred from these studies, one of which is probably a source of gold-bearing quartz veins in the metasedimentary rocks of the Shiaila area.

The role of fluids in rock layering development: a pressure solution self-organized process revealed by laboratory experiments

NASA Astrophysics Data System (ADS)

Gratier, Jean-Pierre; Noiriel, Catherine; Renard, Francois

2015-04-01

Natural deformation of rocks is often associated with stress-driven differentiation processes leading to irreversible transformations of their microstructures. The development mechanisms of such processes during diagenesis, tectonic, metamorphism or fault differentiation are poorly known as they are difficult to reproduce experimentally due to the very slow kinetics of stress-driven chemical processes. Here, we show that experimental compaction with development of differentiated layering, similar to what happens in natural deformation, can be obtained by indenter techniques in laboratory conditions. Samples of plaster mixed with clay and of diatomite loosely interbedded with volcanic dust were loaded in presence of their saturated aqueous solutions during several months at 40°C and 150°C, respectively. High-resolution X-ray microtomography and scanning electron microscopy observations show that the layering development is a pressure solution self-organized process. Stress-driven dissolution of the soluble minerals (either gypsum or silica) is initiated in the areas initially richer in insoluble minerals (clays or volcanic dust) because the kinetics of diffusive mass transfer along the soluble/insoluble mineral interfaces is much faster than along the healed boundaries of the soluble minerals. The passive concentration of insoluble minerals amplifies the localization of dissolution along some layers oriented perpendicular to the maximum compressive stress. Conversely, in the areas with initial low content in insoluble minerals and clustered soluble minerals, dissolution is slower. Consequently, these areas are less deformed, they host the re-deposition of the soluble species and they act as rigid objects that concentrate the dissolution near their boundaries thus amplifying the differentiation. A crucial parameter required for self-organized process of pressure solution is the presence of a fluid that is a good solvent of at least some of the rock-forming minerals

Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock: FY17 Progress. Predecisional Draft

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Liange; Rutqvist, Jonny; Xu, Hao

-Scale Engineered Barrier Experiment Dismantling Project (FEBEX-DP). The data collected in the test after almost two decades of heating and two dismantling events provide a unique opportunity of validating coupled THMC models and enhancing our understanding of coupled THMC process in EBS bentonite. Section 5 presents a planned large in-situ test, “HotBENT,” at Grimsel Test Site, Switzerland. In this test, bentonite backfilled EBS in granite will be heated up to 200 °C, where the most relevant features of future emplacement conditions can be adequately reproduced. Lawrence Berkeley National Laboratory (LBNL) has very actively participated in the project since the very beginning and have conducted scoping calculations in FY17 to facilitate the final design of the experiment. Section 6 presents present LBNL’s activities for modeling gas migration in clay related to Task A of the international DECOVALEX-2019 project. This is an international collaborative activity in which DOE and LBNL gain access to unique laboratory and field data of gas migration that are studied with numerical modeling to better understand the processes, to improve numerical models that could eventually be applied in the performance assessment for nuclear waste disposal in clay host rocks and bentonite backfill. Section 7 summarizes the main research accomplishments for FY17 and proposes future work activities.« less

A comparative study of discrete fracture network and equivalent continuum models for simulating flow and transport in the far field of a hypothetical nuclear waste repository in crystalline host rock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadgu, Teklu; Karra, Satish; Kalinina, Elena

One of the major challenges of simulating flow and transport in the far field of a geologic repository in crystalline host rock is related to reproducing the properties of the fracture network over the large volume of rock with sparse fracture characterization data. Various approaches have been developed to simulate flow and transport through the fractured rock. The approaches can be broadly divided into Discrete Fracture Network (DFN) and Equivalent Continuum Model (ECM). The DFN explicitly represents individual fractures, while the ECM uses fracture properties to determine equivalent continuum parameters. In this paper, we compare DFN and ECM in termsmore » of upscaled observed transport properties through generic fracture networks. The major effort was directed on making the DFN and ECM approaches similar in their conceptual representations. This allows for separating differences related to the interpretation of the test conditions and parameters from the differences between the DFN and ECM approaches. The two models are compared using a benchmark test problem that is constructed to represent the far field (1 × 1 × 1 km 3) of a hypothetical repository in fractured crystalline rock. The test problem setting uses generic fracture properties that can be expected in crystalline rocks. The models are compared in terms of the: 1) effective permeability of the domain, and 2) nonreactive solute breakthrough curves through the domain. The principal differences between the models are mesh size, network connectivity, matrix diffusion and anisotropy. We demonstrate how these differences affect the flow and transport. Finally, we identify the factors that should be taken in consideration when selecting an approach most suitable for the site-specific conditions.« less

A comparative study of discrete fracture network and equivalent continuum models for simulating flow and transport in the far field of a hypothetical nuclear waste repository in crystalline host rock

DOE PAGES

Hadgu, Teklu; Karra, Satish; Kalinina, Elena; ...

2017-07-28

One of the major challenges of simulating flow and transport in the far field of a geologic repository in crystalline host rock is related to reproducing the properties of the fracture network over the large volume of rock with sparse fracture characterization data. Various approaches have been developed to simulate flow and transport through the fractured rock. The approaches can be broadly divided into Discrete Fracture Network (DFN) and Equivalent Continuum Model (ECM). The DFN explicitly represents individual fractures, while the ECM uses fracture properties to determine equivalent continuum parameters. In this paper, we compare DFN and ECM in termsmore » of upscaled observed transport properties through generic fracture networks. The major effort was directed on making the DFN and ECM approaches similar in their conceptual representations. This allows for separating differences related to the interpretation of the test conditions and parameters from the differences between the DFN and ECM approaches. The two models are compared using a benchmark test problem that is constructed to represent the far field (1 × 1 × 1 km 3) of a hypothetical repository in fractured crystalline rock. The test problem setting uses generic fracture properties that can be expected in crystalline rocks. The models are compared in terms of the: 1) effective permeability of the domain, and 2) nonreactive solute breakthrough curves through the domain. The principal differences between the models are mesh size, network connectivity, matrix diffusion and anisotropy. We demonstrate how these differences affect the flow and transport. Finally, we identify the factors that should be taken in consideration when selecting an approach most suitable for the site-specific conditions.« less

A comparative study of discrete fracture network and equivalent continuum models for simulating flow and transport in the far field of a hypothetical nuclear waste repository in crystalline host rock

NASA Astrophysics Data System (ADS)

Hadgu, Teklu; Karra, Satish; Kalinina, Elena; Makedonska, Nataliia; Hyman, Jeffrey D.; Klise, Katherine; Viswanathan, Hari S.; Wang, Yifeng

2017-10-01

One of the major challenges of simulating flow and transport in the far field of a geologic repository in crystalline host rock is related to reproducing the properties of the fracture network over the large volume of rock with sparse fracture characterization data. Various approaches have been developed to simulate flow and transport through the fractured rock. The approaches can be broadly divided into Discrete Fracture Network (DFN) and Equivalent Continuum Model (ECM). The DFN explicitly represents individual fractures, while the ECM uses fracture properties to determine equivalent continuum parameters. We compare DFN and ECM in terms of upscaled observed transport properties through generic fracture networks. The major effort was directed on making the DFN and ECM approaches similar in their conceptual representations. This allows for separating differences related to the interpretation of the test conditions and parameters from the differences between the DFN and ECM approaches. The two models are compared using a benchmark test problem that is constructed to represent the far field (1 × 1 × 1 km3) of a hypothetical repository in fractured crystalline rock. The test problem setting uses generic fracture properties that can be expected in crystalline rocks. The models are compared in terms of the: 1) effective permeability of the domain, and 2) nonreactive solute breakthrough curves through the domain. The principal differences between the models are mesh size, network connectivity, matrix diffusion and anisotropy. We demonstrate how these differences affect the flow and transport. We identify the factors that should be taken in consideration when selecting an approach most suitable for the site-specific conditions.

Clay Cuffman: A Cool, Calm, Relaxed Guy

ERIC Educational Resources Information Center

Booth, Gina

2010-01-01