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Sample records for weathered rock

  1. Space Weathering of Rocks

    NASA Technical Reports Server (NTRS)

    Noble, Sarah

    2011-01-01

    Space weathering discussions have generally centered around soils but exposed rocks will also incur the effects of weathering. On the Moon, rocks make up only a very small percentage of the exposed surface and areas where rocks are exposed, like central peaks, are often among the least space weathered regions we find in remote sensing data. However, our studies of weathered Ap 17 rocks 76015 and 76237 show that significant amounts of weathering products can build up on rock surfaces. Because rocks have much longer surface lifetimes than an individual soil grain, and thus record a longer history of exposure, we can study these products to gain a deeper perspective on the weathering process and better assess the relative impo!1ance of various weathering components on the Moon. In contrast to the lunar case, on small asteroids, like Itokowa, rocks make up a large fraction of the exposed surface. Results from the Hayabusa spacecraft at Itokowa suggest that while the low gravity does not allow for the development of a mature regolith, weathering patinas can and do develop on rock surfaces, in fact, the rocky surfaces were seen to be darker and appear spectrally more weathered than regions with finer materials. To explore how weathering of asteroidal rocks may differ from lunar, a set of ordinary chondrite meteorites (H, L, and LL) which have been subjected to artificial space weathering by nanopulse laser were examined by TEM. NpFe(sup 0) bearing glasses were ubiquitous in both the naturally-weathered lunar and the artificially-weathered meteorite samples.

  2. Weathering of rock 'Ginger'

    NASA Technical Reports Server (NTRS)

    1997-01-01

    One of the more unusual rocks at the site is Ginger, located southeast of the lander. Parts of it have the reddest color of any material in view, whereas its rounded lobes are gray and relatively unweathered. These color differences are brought out in the inset, enhanced at the upper right. In the false color image at the lower right, the shape of the visible-wavelength spectrum (related to the abundance of weathered ferric iron minerals) is indicated by the hue of the rocks. Blue indicates relatively unweathered rocks. Typical soils and drift, which are heavily weathered, are shown in green and flesh tones. The very red color in the creases in the rock surface correspond to a crust of ferric minerals. The origin of the rock is uncertain; the ferric crust may have grown underneath the rock, or it may cement pebbles together into a conglomerate. Ginger will be a target of future super-resolution studies to better constrain its origin.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech).

  3. Space Weathering of Lunar Rocks

    NASA Technical Reports Server (NTRS)

    Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

    2012-01-01

    All materials exposed at the lunar surface undergo space weathering processes. On the Moon, boulders make up only a small percentage of the exposed surface, and areas where such rocks are exposed, like central peaks, are often among the least space weathered regions identified from remote sensing data. Yet space weathered surfaces (patina) are relatively common on returned rock samples, some of which directly sample the surface of larger boulders. Because, as witness plates to lunar space weathering, rocks and boulders experience longer exposure times compared to lunar soil grains, they allow us to develop a deeper perspective on the relative importance of various weathering processes as a function of time.

  4. Rock strength reductions during incipient weathering

    NASA Astrophysics Data System (ADS)

    Kelly, P. J.; Anderson, S. P.; Blum, A.

    2012-12-01

    Patrick Kelly, Suzanne Anderson, Alex Blum In rock below the surface, temperature swings are damped, water flow is limited, and biota are few. Yet rock weathers, presumably driven by these environmental parameters. We use rock strength as an indicator of rock weathering in Gordon Gulch in the Boulder Creek Critical Zone Observatory, a watershed at 2500 m underlain by Proterozoic gneiss intruded by the Boulder Creek granodiorite. Fresh rock is found at depths of 8-30 m in this area, and the thickness of the weathered rock zone imaged with shallow seismic refraction is greater on N-facing slopes than S-facing slopes (Befus et al., 2011, Vadose Zone J.). We use the Brazilian splitting test to determine tensile strength of cores collected with a portable drilling rig. Spatial variations in rock strength that we measure in the top 2 m of the weathered rock mantle can be connected to two specific environmental variables: slope aspect and the presence of a soil mantle. We find weaker rock on N-facing slopes and under soil. There is no clear correlation between rock strength and the degree of chemical alteration in these minimally weathered rocks. Denudation rates of 20-30 microns/yr imply residence times of 105-106 years within the weathered rock layers of the critical zone. Given these timescales, rock weathering is more likely to have occurred under glacial climate conditions, when periglacial processes prevailed in this non-glaciated watershed. Incipient weathering of rock appears to be controlled by water and frost cracking in Gordon Gulch. Water is more effectively delivered to the subsurface on N-facing slopes, and is more likely held against rock surfaces under soil than on outcrops. These moisture conditions, and the lower surface temperatures that prevail on N-facing slopes also favor frost cracking as an important weathering process.

  5. Rock weathering and Carbon cycle

    NASA Astrophysics Data System (ADS)

    Strozza, Patrick

    2010-05-01

    In the history of the Earth system, we can find indicators of hot or glacial periods, as well as brutal climatic change… How can we explain those climate variations on a geological timescale ? One of the causative agents is probably the fluctuation of atmospheric CO2 amounts, (gas responsible for the greenhouse effect). A concrete study of some CO2 fluxes between Earth system reservoirs (atmo, hydro and lithosphere) is proposed in this poster. Hydrogencarbonate is the major ion in river surface waters and its amount is so high that it can not be explained by a simple atmospheric Carbon diffusion. From a simple measurement of river HCO3- concentration, we can estimate the consumption of atmospheric CO2 that arises from carbonate and silicate weathering processes. Practical experiments are proposed. These are carried out in the local environment, and are conform to the curriculums of Chemistry and Earth sciences. These tests enable us to outline long-term Carbon cycles and global climatic changes. Key words : Erosion, rock weathering, CO2 cycle, Hydrogencarbonate in waters, climatic changes

  6. The Weathering of Rocks: Three Activities.

    ERIC Educational Resources Information Center

    McLure, John W.

    1991-01-01

    Integrates science and social studies in several activities that study weathering caused by the freezing and thawing of rocks, wind erosion, and the effects of weathering on tombstones. Cites the possibility of these activities leading to an interdisciplinary exploration of pollution, customs, and populations. (MCO)

  7. Deeply weathered basement rocks in Norway

    NASA Astrophysics Data System (ADS)

    Bönner, Marco; Knies, Jochen; Fredin, Ola; Olesen, Odleiv; Viola, Giulio

    2014-05-01

    Recent studies show that, in addition to tectonic processes, surface processes have also had a profound impact on the topography of Norway. This is especially obvious for the northernmost part of the Nordland county and for western Norway, where the current immature Alpine-type topography cannot be easily explained by tectonic processes only. Erosion of the sedimentary succession also does not seem sufficient to explain the observed relief. Common remnants of deeply weathered basement rocks, however, indicate a history of deep alteration and later erosion of the bedrock, which needs to be considered as another important factor in the development of the topographic relief. Most of the sites with deeply weathered basement exhibit a clay-poor grussy type of weathering, which is generally considered to be of relatively young age (Plio-/Pleistocene) and thought to represent an intermediate stage of weathering. Unfortunately, small amounts or complete absence of clay minerals in these weathering products precluded the accurate dating of this weathered material. Scandinavia was exposed to a large range of glaciations and the once extensive sedimentary successions have been almost entirely eroded, which impedes a minimum age estimate of the weathering profile. Although several sites preserving remnants of deep weathering can still be observed onshore Norway, they are all covered by Quaternary overburden and the age of the regolith remains thus unconstrained and a matter of debate. The only exception is a small Mesozoic basin on Andøya, northern Norway, where weathered and clay-poor saprolite was found underlying Jurassic and Cretaceous sedimentary rocks. Over the last few years the Geological Survey of Norway (NGU) has mapped and investigated deep weathering onshore Norway to better understand weathering processes and to constrain the age of the weathering remnants. The combined interpretation of geophysical, mineralogical and geochemical data, together with recent

  8. Building Stone and Its Use in Rock Weathering Studies.

    ERIC Educational Resources Information Center

    Dragovich, Deirdre

    1979-01-01

    Building stone provides opportunities for geological study of weathering of different rocks in a particular environment and similar rocks in different environment. The principle studied can be applied on a large scale from the observation of small-scale weathering. Examples of weathering are drawn mainly from the Sydney region of Australia. (RE)

  9. Take a Tumble: Weathering and Erosion Using a Rock Tumbler

    ERIC Educational Resources Information Center

    Coffey, Patrick; Mattox, Steve

    2006-01-01

    Weathering--the physical and chemical breakdown of geologic materials--and erosion--the transport of materials by wind, water, or ice--can be subtle, yet powerful forces. For example, shale, a rock made of mud-sized particles, is by far the most common sedimentary rock, a testament to the ability of weathering and erosion to take a rock and reduce…

  10. Rock-weathering rates as functions of time

    USGS Publications Warehouse

    Colman, Steven M.

    1981-01-01

    The scarcity of documented numerical relations between rock weathering and time has led to a common assumption that rates of weathering are linear. This assumption has been strengthened by studies that have calculated long-term average rates. However, little theoretical or empirical evidence exists to support linear rates for most chemical-weathering processes, with the exception of congruent dissolution processes. The few previous studies of rock-weathering rates that contain quantitative documentation of the relation between chemical weathering and time suggest that the rates of most weathering processes decrease with time. Recent studies of weathering rinds on basaltic and andesitic stones in glacial deposits in the western United States also clearly demonstrate that rock-weathering processes slow with time. Some weathering processes appear to conform to exponential functions of time, such as the square-root time function for hydration of volcanic glass, which conforms to the theoretical predictions of diffusion kinetics. However, weathering of mineralogically heterogeneous rocks involves complex physical and chemical processes that generally can be expressed only empirically, commonly by way of logarithmic time functions. Incongruent dissolution and other weathering processes produce residues, which are commonly used as measures of weathering. These residues appear to slow movement of water to unaltered material and impede chemical transport away from it. If weathering residues impede weathering processes then rates of weathering and rates of residue production are inversely proportional to some function of the residue thickness. This results in simple mathematical analogs for weathering that imply nonlinear time functions. The rate of weathering becomes constant only when an equilibrium thickness of the residue is reached. Because weathering residues are relatively stable chemically, and because physical removal of residues below the ground surface is slight

  11. On the weathering of Martian igneous rocks

    NASA Technical Reports Server (NTRS)

    Dreibus, G.; Waenke, H.

    1992-01-01

    Besides the young crystallization age, one of the first arguments for the martian origin of shergottite, nakhlite, and chassignite (SNC) meteorites came from the chemical similarity of the meteorite Shergotty and the martian soil as measured by Viking XRF analyses. In the meantime, the discovery of trapped rare gas and nitrogen components with element and isotope ratios closely matching the highly characteristic ratios of the Mars atmosphere in the shock glasses of shergottite EETA79001 was further striking evidence that the SNC's are martian surface rocks. The martian soil composition as derived from the Viking mission, with its extremely high S and Cl concentrations, was interpreted as weathering products of mafic igneous rocks. The low SiO2 content and the low abundance of K and other trace elements in the martian soils point to a mafic crust with a considerably smaller degree of fractionation compared to the terrestrial crust. However, the chemical evolution of the martian regolith and soil in respect to surface reaction with the planetary atmosphere or hydrosphere is poorly understood. A critical point in this respect is that the geochemical evidence as derived from the SNC meteorites suggests that Mars is a very dry planet that should have lost almost all its initially large water inventory during its accretion.

  12. Characterizing and modelling 'ghost-rock' weathered limestones

    NASA Astrophysics Data System (ADS)

    Dubois, Caroline; Goderniaux, Pascal; Deceuster, John; Poulain, Angélique; Kaufmann, Olivier

    2016-04-01

    'Ghost-rock' karst aquifer has recently been highlighted. In this particular type of aquifer, the karst is not expressed as open conduits but consists in zones where the limestone is weathered. The in-situ weathering of limestone leaves a soft porous material called 'alterite'. The hydro-mechanical properties of this material differs significantly from those of the host rock: the weathering enhances the storage capacity and the conductivity of the rock. This type of weathered karst aquifer has never been studied from a hydrogeological point of view. In this study, we present the hydraulic characterization of such weathered zones. We also present a modelling approach derived from the common Equivalent Porous Medium (EPM) approach, but including the spatial distribution of hydrogeological properties through the weathered features, from the hard rock to the alterite, according to a weathering index. Unlike the Discrete Fracture Network (DFN) approaches, which enable to take into account a limited number of fractures, this new approach allows creating models including thousands of weathered features. As the properties of the alterite have to be considered at a centimeter scale, it is necessary to upscale these properties to carry out simulations over large areas. Therefore, an upscaling method was developed, taking into account the anisotropy of the weathered features. Synthetic models are built, upscaled and different hydrogeological simulations are run to validate the method. This methodology is finally tested on a real case study: the modelling of the dewatering drainage flow of an exploited quarry in a weathered karst aquifer in Belgium.

  13. Physical and chemical weathering. [of Martian surface and rocks

    NASA Technical Reports Server (NTRS)

    Gooding, James L.; Arvidson, Raymond E.; Zolotov, Mikhail IU.

    1992-01-01

    Physical and chemical weathering processes that might be important on Mars are reviewed, and the limited observations, including relevant Viking results and laboratory simulations, are summarized. Physical weathering may have included rock splitting through growth of ice, salt or secondary silicate crystals in voids. Chemical weathering probably involved reactions of minerals with water, oxygen, and carbon dioxide, although predicted products vary sensitively with the abundance and physical form postulated for the water. On the basis of kinetics data for hydration of rock glass on earth, the fate of weathering-rind formation on glass-bearing Martian volcanic rocks is tentatively estimated to have been on the order of 0.1 to 4.5 cm/Gyr; lower rates would be expected for crystalline rocks.

  14. Subsurface Weathering of Rocks and Soils at Gusev Crater

    NASA Technical Reports Server (NTRS)

    Yen, A. S.; Ming, D. W.; Gellert, R.; Clark, B. C.; Morris, R. V.; Rodionov, D.; Schroeder, C.

    2005-01-01

    Data collected by the Mars Exploration Rover (MER) Spirit at Gusev Crater suggest that enhanced weathering of rocks and soils occurs beneath the immediate surface. We suggest that this alteration occurs over geological timescales under present climatic conditions and is a result of diurnal condensation of thin-films of water on subsurface materials. Additional information is included in the original extended abstract.

  15. Evidence for non-Gaussian distribution of rock weathering rates

    NASA Astrophysics Data System (ADS)

    Emmanuel, S.

    2015-07-01

    The weathering of rocks influences the geochemistry of the oceans, the erosion of landscapes and manmade structures, and even the global climate. Although a high degree of variance is often observed in rate measurements, little is understood about the statistical characteristics of weathering rate distributions. This preliminary study demonstrates that the weathering rates of limestone, determined from measurements of an ancient eroded limestone edifice, can exhibit highly non-Gaussian behavior. While a Gaussian model produced a poor fit with the data, an alternative model - the generalized extreme value (GEV) framework - was capable of capturing the asymmetric long tailed distribution, in good agreement with the measured curve. Furthermore, the non-Gaussian distribution of these field rates was found to have similar characteristics to the distribution of rates measured over much smaller microscopic regions of limestone surfaces in laboratory experiments. Such similar behavior could be indicative of analogous chemical and mechanical weathering processes acting over a range of different spatial and temporal scales. Moreover, highly asymmetric rate distributions with high variance could be characteristic of rates not only in carbonate rocks, but in other rock types too, suggesting that the use of a small number of measurements to determine field weathering rates may be insufficient to fully characterize the range of rates in natural systems.

  16. Association of trace elements with iron oxides during rock weathering

    SciTech Connect

    Koons, R.D.; Helmke, P.A.; Jackson, M.L.

    1980-01-01

    The association of trace elements with Fe oxides during the early stages of rock weathering was determined by analysis of fresh diabase and granite rocks, their associated whole and size-separated saprolites, and goethite by neutron activation and X-ray fluorescence. The same elements are found to be associated with Fe oxides when the results are interpreted by analysis of correlation, by the distribution of elements in the various size fractions by the effects of removing free Fe oxides, and by direct analysis of geothite from the saprolite. The elements Co, Cr, Mn, Sc, Th, U, Zn, and the heavy rare-earth elements during the weathering of diabase, and As, Co, Cr, Sc, Th, U, Zn, and the heavy rare-earth elements during the weathering of granite are associated with Fe oxides. The concentrations of Mn are too low in this system to separate the effects of Mn oxides from those of Fe oxides.

  17. Modelling study on uranium migration in rocks under weathering condition

    SciTech Connect

    Ohnuki, Toshihiko; Isobe, Hiroshi; Sato, Tsutomu; Yanase, Nobuyuki; Murakami, Takashi

    1995-12-31

    A modelling study has been completed to understand the effect of rock alteration on uranium migration at the Koongarra ore deposit, Australia. The model considers the weathering process, the mechanism and rate of chlorite alteration, a major mineral of the host rock, and assumes the presence of reversible sorption sites of chlorite and the presence of reversible and irreversible sorption sites of the weathering products. One- and two-dimensional, calculated uranium concentrations were compared with those observed. Good agreement between the calculated and observed uranium concentration profiles was obtained only when an appropriate fraction of uranium is fixed to the irreversible sorption sites of Fe-minerals produced during weathering of chlorite. On the other hand, the conventional Kd model failed to estimate an adequate uranium concentration profile. The results suggest that the fixation of uranium to Fe-minerals has dominated the migration of uranium in the vicinity of the Koongarra ore deposit.

  18. Rock Rinds at Meridiani and Surface Weathering Phenomena

    NASA Astrophysics Data System (ADS)

    Jolliff, B.; Knoll, A.; Farrand, W.; Sullivan, R.

    2006-12-01

    The Rock Abrasion Tool (RAT) on the Mars rover Opportunity can brush away surface dust and grind away outcrop surface, exposing presumably less altered rock at depths of several mm. Alpha particle X-ray spectrometer (APXS) and Moessbauer spectrometer (MB) analyses of pre- and post-RAT targets, thus, provide information on the chemical nature of weathering of Meridiani outcrop rocks. To date, Opportunity has analyzed some 25 undisturbed rock surfaces, brushed and then analyzed 7 more, and ground 23 targets for IDD analysis. Panoramic camera images show that outcrop surfaces are typically either buff or purple (as viewed in bands centered at 673, 535, and 432 nm, Farrand et al., JGR, in press). Relatively flat surfaces that are approximately parallel to the ground are typically buff, whereas those that slope steeply tend to be purple. Surfaces of rock interiors ground by the RAT are also commonly purple. Spectrally, these color differences correspond to more oxidized (buff) and less oxidized (purple), and appear to relate to the degree of eolian abrasion. Flat-lying surfaces are not eroded as quickly, thus surfaces chemically weathered by exposure to tenuous atmospheric vapor may be preserved. These observations are consistent with in-situ analyses of rock surfaces and interiors. Compared to interiors, rock surfaces have about 1/3 less S, and in general, surface compositions lie between those of rock interiors and average surface soil. In detail, they differ from soil-rock mixtures as follows: surfaces are relatively depleted in Mg, Fe, Mn, Ti, and Cr, and they are enriched in Al, Na, K, P, Cl, and Si. From MB analyses, surfaces are richer (compared to soil-rock mixtures) in oxidized Fe phases and poorer in magnetite, olivine, and pyroxene. Morphologically, numerous flat-lying rocks and outcrop surfaces that are at or near the ground surface have a rind of erosionally resistant material. Such rinds are also chemically distinct from outcrop interiors. A rind

  19. Weathered stony meteorites from Victoria Land, Antarctica, as possible guides to rock weathering on Mars

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1984-01-01

    Parallel studies of Martian geomorphic features and their analogs on Earth continue to be fruitful in deciphering the geologic history of Mars. In the context of rock weathering, the Earth-analog approach is admirably served by the study of meteorites recovered from ice sheets in Antarctica. The weathering environment of Victoria Land possesses several Mars-like attributes. Four of the five Antarctic meteorites being studied contain rust and EETA79005 further possesses a conspicuous, dark, weathering rind on one side. Secondary minerals (rust and salts) occur both on the surfaces and interiors of some of the samples and textural evidence indicates that such secondary mineralization contributed to physical weathering (by salt riving) of the rocks. Several different rust morphologies occur and emphasis is being placed on identifying the phase compositions of the various rust occurrances. A thorough understanding of terrestrial weathering features of the meteorites is a prerequisite for identifying possible Martian weathering features (if such features exist) that might be postulated to occur in some meteorites.

  20. Space Weathering of Lunar Rocks and Regolith Grains

    NASA Technical Reports Server (NTRS)

    Keller, L. P.

    2013-01-01

    The exposed surfaces of lunar soil grains and lunar rocks become modified and coated over time with a thin rind of material (patina) through complex interactions with the space environment. These interactions encompass many processes including micrometeorite impacts, vapor and melt deposition, and solar wind implantation/sputtering effects that collectively are referred to as "space weathering". Studies of space weathering effects in lunar soils and rocks provide important clues to understanding the origin and evolution of the lunar regolith as well as aiding in the interpretation of global chemical and mineralogical datasets obtained by remote-sensing missions. The interpretation of reflectance spectra obtained by these missions is complicated because the patina coatings obscure the underlying rock mineralogy and compositions. Much of our understanding of these processes and products comes from decades of work on remote-sensing observations of the Moon, the analysis of lunar samples, and laboratory experiments. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Space weathering effects are largely surface-correlated, concentrated in the fine size fractions, and occur as amorphous rims on individual soil grains. Rims on lunar soil grains are highly complex and span the range between erosional surfaces modified by solar wind irradiation to depositional surfaces modified by the condensation of sputtered ions and impact-generated vapors. The optical effects of space weathering effects are directly linked to the production of nanophase Fe metal in lunar materials]. The size of distribution of nanophase inclusions in the rims directly affect optical properties given that large Fe(sup o) grains (approx 10 nm and larger) darken the sample (lower albedo) while the tiny Fe(sup o) grains (<5nm

  1. Generalized soil Thaumarchaeota community in weathering rock and saprolite.

    PubMed

    Dong, Ke; Kim, Woo-Sung; Tripathi, Binu Mani; Adams, Jonathan

    2015-02-01

    Relatively little is known of the archaeal communities associated with endolithic environments, compared to other microbial groups such as bacteria and fungi. Analyzing the pyrosequenced archaeal 16S ribosomal RNA (rRNA) gene V1-V3 region, we investigated the archaeal community associated with aboveground-exfoliated weathering layers of a granite gneiss, and of the saprolite derived from this rock at 1 m depth below the soil surface, in a forested hilly area south of Seoul, South Korea. In both these sites, an archaeal community dominated by the phylum Thaumarchaeota was identified. The archaeal community in all cases closely resembled that of the surface layer of acidic soils in temperate climates of Korea. It appears that there is no clear distinction in archaeal community composition between a soil and a rock and a saprolite despite a tremendous difference in the concentration of total nitrogen and organic carbon. Of the chemical properties we measured, pH was the best predictor of the archaeal community composition and relative abundance of thaumarchaeal subphyla. These findings reinforce the view that soil archaea are mostly generalists, whose ecology is not closely dependent on nitrogen concentration or soil organic matter status, the presence of living roots, or the abundant presence of any other biota. PMID:25370886

  2. Effects of Weathering on Basaltic Rocks and Their Thermal Emission Spectra: Implications for Evaluating Mars Mineralogy and Weathering

    NASA Astrophysics Data System (ADS)

    Kraft, M. D.; Michalski, J. R.; Sharp, T. G.

    2005-12-01

    Thermal emission spectroscopy has provided crucial information about the mineralogical composition of the Martian surface. Portions of that surface may be chemically weathered, and it is, therefore, important that the influence of chemical weathering on thermal infrared observations be recognized and understood. To this end, we have examined a suite of weathered rocks collected from the Columbia River Basalt Group. Weathering causes distinct changes to the thermal emissivity spectra of these basalts, which will be discussed in detail by J. R. Michalski et al. (this meeting). Here, we document physical and mineralogical features of weathering rinds to understand how weathering affects infrared spectra. Chemical weathering of basalts forms microcracks, dissolves primary minerals, and produces secondary phases. In the rocks examined, the relative abundance of primary minerals is the same in the weathering rind and corresponding unweathered rock. This is true even for olivine, the least stable phase in the rocks studied. Thus, preferential dissolution is not a controlling factor in the observed spectral changes. Microcracks form by expansion and dissolution and represent <20 vol% of the weathering rinds studied. While they potentially act as blackbody cavities, they probably influence emissivity spectra more by acting as sites where secondary phases form. Because the cracks are generally a few micrometers in width, the secondary phases filling them are optically thin, which may produce nonlinearity in spectral mixing of mineral phases, complicating spectral modeling. Secondary phases are Si-Al-rich and strongly influence the Si-O stretching region of infrared spectra. Dissolution of silica from primary phases and its precipitation in microcracks are the principle factors controlling changes in emissivity spectra in weathered rocks. These changes can lead to inaccurate relative abundances of primary phases derived from deconvolution modeling of weathered rocks. Also

  3. Field Guide to Rock Weathering. Earth Science Curriculum Project Pamphlet Series PS-1.

    ERIC Educational Resources Information Center

    Boyer, Robert E.

    Highlighted are the effects of weathering through field investigations of the environment, both natural rocks, and the urban environment's pavements, buildings, and cemeteries. Both physical weathering and chemical weathering are discussed. Questions are presented for post-field trip discussion. References and a glossary are provided. (Author/RE)

  4. New weathering indices for evaluating durability and weathering characterization of crystalline rock material: A case study from NE Turkey

    NASA Astrophysics Data System (ADS)

    Ceryan, Sener

    2015-03-01

    There are several methods to characterize petrochemical properties of crystalline rocks. One method is based on the ionic model. In the model, large oxygen atoms of the rock-forming minerals are close-packed framework structures. The distribution of cations, which is defined by the "Cation-Packing Index" or the k-value for each (stoichiometric) mineral phase, can be correlated with the petrophysical properties. These properties, representing the engineering behavior of the rock materials show a dependence on the physical and chemical changes due to weathering. The fundamental systems of the chemical weathering of rocks are the leaching of the alkaline and alkali-earth elements and the redistribution of the residual elements into secondary minerals. In this study, these conditions are considered as the basis for new petro-chemical weathering indices based on the cation-packing value for evaluating weathering characterization of crystalline rocks. These indices are the k-product index, the k-leaching index and the k-weathering index. The k-product index represents the quantity of the weathering product suggested in this study, whereas the k-leaching index represents the amount of chemical leaching during the weathering. The k-weathering index was defined as the sum of the k-leaching index and the k-product index. In addition to these new engineering indices, a k-durability index based on a slake durability index and the k-value of the rock materials was suggested in this study to estimate the durability and the mechanical properties of rock materials. These indices were applied to granitic rock samples weathered to various degrees, from the Kurtun Granodiorite in northeastern Turkey. The results of the regression analysis performed in this study show that the k-weathering index can be used as a weathering indicator and that the k-durability index can be used to evaluate the durability and the mechanical behaviors of the investigated samples. It would be useful to

  5. Chitinophaga qingshengii sp. nov., isolated from weathered rock surface.

    PubMed

    Cheng, Cheng; Wang, Qi; He, Lin-Yan; Huang, Zhi; Sheng, Xia-Fang

    2015-01-01

    A novel mineral-weathering bacterium was isolated from weathered rock (potassic trachyte) surfaces collected from Nanjing (Jiangsu, PR China). Cells of strain JN246(T) were Gram-stain-negative, rod-shaped and non-motile. Strain JN246(T) was aerobic, catalase- and oxidase-positive, and grew optimally at 28 °C and pH 7.0. On the basis of 16S rRNA gene sequence analysis, strain JN246(T) belonged to the genus Chitinophaga and the closest phylogenetic relatives were Chitinophaga eiseniae YC6729(T) (98.5% 16S rRNA gene sequence similarity), Chitinophaga terrae KP01(T) (96.8%), and Chitinophaga jiangningensis JN53(T) (96.3 %). The major respiratory quinone was MK-7 and the major polyamine was homospermidine. The major fatty acids were iso-C15:0, C16:1ω5c, C16:0 and iso-C17:0 3-OH. The polar lipid profile of strain JN246(T) consisted of phosphatidylethanolamine, unknown aminolipids and unknown lipids. The genomic DNA G+C content of strain JN246(T) was 48.8 mol%. Based on the low level of DNA-DNA relatedness of strain JN246(T) (ranging from 22.6% to 42.4%) to the type strains of other species of the genus Chitinophaga and unique phenotypic characteristics, strain JN246(T) represents a novel species of the genus Chitinophaga, for which the name Chitinophaga qingshengii sp. nov. is proposed. The type strain is JN246(T) ( = CCTCC AB 2014201(T) = JCM 30026(T)). PMID:25342110

  6. Weathering of expansive sedimentary rock due to cycles of wetting and drying

    SciTech Connect

    Day, R.W. )

    1994-09-01

    There are several different mechanisms by which sedimentary rock can weather, such as: (1) Rebound: for cut areas, where the overburden has been removed by erosion or during mass-grading operations, the sedimentary rock will rebound due to the release in overburden pressure, the rebound can cause the opening or widening of cracks and joints; (2) Physical Weathering: sedimentary rock can be broken apart by the physical growth of plant roots or by the freezing of water in rock cracks or joints. Studies have also shown that precipitation of gypsum in rock pores, cracks, and joints can cause rock expansion and disintegration. Such conditions occur in arid climates where subsurface moisture evaporates at ground surface, precipitating the minerals in the rock pores. Acicular gypsum crystals have been observed to grow perpendicular to structures and are believed to exert the most force at their growing end (Hawkins and Pinces, 1987). Acicular gypsum growth has even been observed in massive sandstone, which resulted in significant heave (Hollingsworth and Grover, 1992); (3) Chemical Weathering: weathering of sedimentary rock can be due to oxidation, hydration of clay minerals, and the chemical alteration of the silt-size particles to clay. Factors affecting oxidation include the presence of moisture and oxygen (aerobic conditions), biological activity, acidic environment, and temperature (Hollingsworth and Grover, 1992). The purpose of this study was to investigate the weathering of expansive sedimentary rock due to cycles of wetting and drying at temperatures representative of field conditions.

  7. An Examination of the Space Weathering Patina of Lunar Rock 76015

    NASA Technical Reports Server (NTRS)

    Noble, S.; Chrisoffersen, R.; Rahman, Z.

    2011-01-01

    Space weathering discussions have generally centered around soils but exposed rocks will also incur the effects of weathering. Rocks have much longer surface lifetimes than an individual soil grain and thus record a longer history of exposure. By studying the weathering products which have built up on a rock surface, we can gain a deeper perspective on the weathering process and better assess the relative importance of various weathering components. The weathered coating, or patina, of the lunar rock 76015 has been previously studied under SEM and also by TEM using ultramicrotome sample preparation methods. However, to really understand the products involved in creating these coatings, it is helpful to examine the patina in cross section, something which is now possible though the use of Focused Ion Beam (FIB) sample prep techniques, which allows us to preserve intact the delicate stratigraphy of the patina coating and provides a unique cross-sectional view of the space weathering process. Several samples have been prepared from the rock and the coatings are found to be quite variable in thickness and composition from one sample to the next.

  8. The effect of rock composition on cyanobacterial weathering of crystalline basalt and rhyolite.

    PubMed

    Olsson-Francis, K; Simpson, A E; Wolff-Boenisch, D; Cockell, C S

    2012-09-01

    The weathering of volcanic rocks contributes significantly to the global silicate weathering budget, effecting carbon dioxide drawdown and long-term climate control. The rate of chemical weathering is influenced by the composition of the rock. Rock-dwelling micro-organisms are known to play a role in changing the rate of weathering reactions; however, the influence of rock composition on bio-weathering is unknown. Cyanobacteria are known to be a ubiquitous surface taxon in volcanic rocks. In this study, we used a selection of fast and slow growing cyanobacterial species to compare microbial-mediated weathering of bulk crystalline rocks of basaltic and rhyolitic composition, under batch conditions. Cyanobacterial growth caused an increase in the pH of the medium and an acceleration of rock dissolution compared to the abiotic controls. For example, Anabaena cylindrica increased the linear release rate (R(i)(l)) of Ca, Mg, Si and K from the basalt by more than fivefold (5.21-12.48) and increased the pH of the medium by 1.9 units. Although A. cylindrica enhanced rhyolite weathering, the increase in R(i)(l) was less than threefold (2.04-2.97) and the pH increase was only 0.83 units. The R(i)(l) values obtained with A. cylindrica were at least ninefold greater with the basalt than the rhyolite, whereas in the abiotic controls, the difference was less than fivefold. Factors accounting for the slower rate of rhyolite weathering and lower biomass achieved are likely to include the higher content of quartz, which has a low rate of weathering and lower concentrations of bio-essential elements, such as, Ca, Fe and Mg, which are known to be important in controlling cyanobacterial growth. We show that at conditions where weathering is favoured, biota can enhance the difference between low and high Si-rock weathering. Our data show that cyanobacteria can play a significant role in enhancing rock weathering and likely have done since they evolved on the early Earth. PMID:22694082

  9. Microbial populations and activities in the rhizoplane of rock-weathering desert plants. I. Root colonization and weathering of igneous rocks.

    PubMed

    Puente, M E; Bashan, Y; Li, C Y; Lebsky, V K

    2004-09-01

    Dense layers of bacteria and fungi in the rhizoplane of three species of cactus (Pachycereus pringlei, Stenocereus thurberi, Opuntia cholla) and a wild fig tree (Ficus palmeri) growing in rocks devoid of soil were revealed by bright-field and fluorescence microscopy and field emission scanning electron microscopy. These desert plants are responsible for rock weathering in an ancient lava flow at La Purisima-San Isidro and in sedimentary rock in the Sierra de La Paz, both in Baja California Sur, Mexico. The dominant bacterial groups colonizing the rhizoplane were fluorescent pseudomonads and bacilli. Seven of these bacterial species were identified by the 16S rRNA molecular method. Unidentified fungal and actimomycete species were also present. Some of the root-colonizing microorganisms fixed in vitro N(2), produced volatile and non-volatile organic acids that subsequently reduced the pH of the rock medium in which the bacteria grew, and significantly dissolved insoluble phosphates, extrusive igneous rock, marble, and limestone. The bacteria were able to release significant amounts of useful minerals, such as P, K, Mg, Mn, Fe, Cu, and Zn from the rocks and were thermo-tolerant, halo-tolerant, and drought-tolerant. The microbial community survived in the rhizoplane of cacti during the annual 10-month dry season. This study indicates that rhizoplane bacteria on cacti roots in rock may be involved in chemical weathering in hot, subtropical deserts. PMID:15375735

  10. Chitinophaga longshanensis sp. nov., a mineral-weathering bacterium isolated from weathered rock.

    PubMed

    Gao, Shan; Zhang, Wen-Bin; Sheng, Xia-Fang; He, Lin-Yan; Huang, Zhi

    2015-02-01

    A Gram-stain-negative, aerobic, yellow-pigmented, non-motile, non-spore-forming, rod-shaped bacterial strain, Z29(T), was isolated from the surface of weathered rock (potassic trachyte) from Nanjing, Jiangsu Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain Z29(T) belongs to the genus Chitinophaga in the family Chitinophagaceae. Levels of 16S rRNA gene sequence similarity between strain Z29(T) and the type strains of recognized species of the genus Chitinophaga ranged from 92.7 to 98.2 %. The main fatty acids of strain Z29(T) were iso-C15 : 0, C16 : 1ω5c and iso-C17 : 0 3-OH. It also contained menaquinone 7 (MK-7) as the respiratory quinone and homospermidine as the main polyamine. The polar lipid profile contained phosphatidylethanolamine, unknown aminolipids, unknown phospholipids and unknown lipids. The total DNA G+C content of strain Z29(T) was 51.3 mol%. Phenotypic properties and chemotaxonomic data supported the affiliation of strain Z29(T) with the genus Chitinophaga. The low level of DNA-DNA relatedness (ranging from 14.6 to 29.8 %) to the type strains of other species of the genus Chitinophaga and differential phenotypic properties demonstrated that strain Z29(T) represents a novel species of the genus Chitinophaga, for which the name Chitinophaga longshanensis sp. nov. is proposed. The type strain is Z29(T) ( = CCTCC AB 2014066(T) = LMG 28237(T)). PMID:25376849

  11. Probing the Depths of Space Weathering: A Cross-sectional View of Lunar Rock 76015

    NASA Technical Reports Server (NTRS)

    Noble, Sarah K.; Keller, L. P.; Stroud, Rhonda

    2007-01-01

    The term "space weathering" refers to the cumulative effects of several processes operating at the surface of any solar system body not protected by a thick atmosphere. These processes include cosmic and solar ray irradiation, solar wind implantation and sputtering, as well as melting and vaporization due to micrometeorite bombardment. Space weathering discussions have generally centered around soils but exposed rocks will also incur the effects of weathering. Rocks have much longer surface lifetimes than an individual soil grain and thus record a longer history of exposure. By studying the weathering products which have built up on a rock surface, we can gain a deeper perspective on the weathering process and better assess the relative importance of various weathering components. The weathered coating, or patina, of the lunar rock 76015 has been previously studied using SEM and TEM. It is a noritic breccia with both "glazed" (smooth glassy) and "classic" (microcratered and pancake-bearing) patina coatings. Previous TEM work on 76015 relied on ultramicrotomy to prepare cross sections of the patina coating, but these sections were limited by the "chatter" and loss of material in these brittle samples. Here we have used a focused ion beam (FIB) instrument to prepare cross sections in which the delicate stratigraphy of the patina coating is beautifully preserved.

  12. Uranium thorium chronometry of weathering rinds: Rock alteration rate and paleo-isotopic record of weathering fluids

    NASA Astrophysics Data System (ADS)

    Pelt, E.; Chabaux, F.; Innocent, C.; Navarre-Sitchler, A. K.; Sak, P. B.; Brantley, S. L.

    2008-11-01

    The potential of 238U- 234U- 230Th chronometry for constraining the formation rate of weathering rinds developed on fresh rocks is assessed by analyzing a weathering rind on a basaltic clast from a 125 kyr old Costa Rican alluvial terrace. Eighteen subsamples were collected from one section of the clast by drilling cores (4 mm in diameter and 5 mm depth) along two transects straddling the core-rind boundary. Variations of major and trace element concentrations along the two transects point out (a) intense loss of alkaline and alkaline-earth elements, (b) conservative behaviour of elements such as Zr, Hf and Th, and (c) external input of U into the rind without any evidence of U loss during basalt weathering. In addition, variations in U concentrations along the transects show that the main U-Th fractionation process associated with the weathering of the basaltic clast is an external input of U (without addition nor loss of Th) in the basalt rind transition zone, and that, once deposited U is immobile in the weathering rind. In the frame of this interpretation scheme, a weathering rate of 0.5 ± 0.2 mm/kyr can be calculated for the studied clast, which is consistent with geological and isotopic evidence constraining the depositional ages of the terraces. In addition, the variations in the ( 234U/ 238U) ratio along the analysed transects as well as the increase in Sr isotopic ratios within the weathering rind are best explained by temporal variation of the U activity ratios and Sr isotope ratios of the soil solutions brought into the rind. This work highlights how well detailed U-Th chronological studies of weathering rinds can (1) constrain the formation rates of weathering systems, and (2) record the time variation of isotopic composition of weathering fluids.

  13. [Role of microscopic fungi in the process of weathering of pegmatite deposit rocks and minerals].

    PubMed

    Avakian, Z A; Karavaiko, G I; Mel'nikova, E O; Krutsko, V S; Ostroushko, Iu I

    1981-01-01

    The object of this work was to study the effect of microscopic fungi isolated from the weathering zone of a pegmatite deposit on the transport of elements and the degradation of rocks and minerals. Regardless of the chemical composition of rocks and minerals, microscopic fungi accelerated the leaching of elements as compared to the purely chemical process. The extraction of Li, Si, Al and Fe under the action of microorganisms increased by factors of 1.4-1.7, 2.7-4.0, 5.0-8.7 and 4-18, respectively. In the case of chemical weathering, the extraction of elements occurred at a high rate only at the beginning; then the process either decelerated or stopped. The mechanism of action of microscopic fungi on rocks and minerals is discussed as well as the role of these microorganisms in the weathering of spodumene and the surrounding rocks, pegmatites an shales, which occurs in the zone of hypergenesis. PMID:7194415

  14. Geoelectric investigations into sandstone moisture regimes: Implications for rock weathering and the deterioration of San Rock Art in the Golden Gate Reserve, South Africa

    NASA Astrophysics Data System (ADS)

    Mol, L.; Viles, H. A.

    2010-06-01

    The Clarens sandstone in the Golden Gate Reserve, South Africa, is the canvas for a collection of San (Bushmen) Rock Art, dating from Neolithic times until as recently as 150 years ago. This Rock Art is under threat from human interference but also, to a greater degree, from weathering processes on the rock surface. The dominant weathering processes occurring in the rock shelters which host the Rock Art are flaking and honeycombing. Two rock shelter sites in the Reserve have been investigated using electric resistivity tomography (ERT) and supportive methods for measuring surface moisture (Protimeter) and surface hardness (Equotip). These non-destructive techniques can be used in situ to assess the extent of weathering within a rock outcrop and are especially suited for investigations in sensitive areas such as Rock Art sites. Moisture movement has been mapped and related to the weathering processes observed on the surface. The aim of the study is to aid Rock Art conservation in the Golden Gate Reserve through a better understanding of the driving processes of surface weathering. The evidence shows that the extensive flaking and honeycombing found in the rock shelters is most likely caused by water pockets in the near-surface zone, which are replenished through internal moisture transport, driving the superficial weathering processes. These weathering processes pose a significant problem: Rock Art in the Golden Gate Reserve shows severe deterioration due to flaking. Conservation strategies should therefore take internal processes into account as much as their superficial expression.

  15. Porosity and surface area evolution during weathering of two igneous rocks

    SciTech Connect

    Navarre-Sitchler, Alexis; Cole, David; Rother, Gernot; Jin, Lixin; Buss, Heather; Brantley, S. L.

    2013-01-01

    During weathering, rocks release nutrients and storewater vital for growth ofmicrobial and plant life. Thus, the growth of porosity as weathering advances into bedrock is a life-sustaining process for terrestrial ecosystems. Here, we use small-angle and ultra small-angle neutron scattering to show how porosity develops during initial weathering under tropical conditions of two igneous rock compositions, basaltic andesite and quartz diorite. The quartz diorite weathers spheroidally while the basaltic andesite does not. The weathering advance rates of the two systems also differ, perhaps due to this difference in mechanism, from 0.24 to 100 mm kyr1, respectively. The scattering data document how surfaces inside the feldspar-dominated rocks change as weathering advances into the protolith. In the unaltered rocks, neutrons scatter fromtwo types of featureswhose dimensions vary from6 nmto 40 lm: pores and bumps on pore grain surfaces. These features result in scattering data for both unaltered rocks that document multi-fractal behavior: scattering is best described by amass fractal dimension (Dm) and a surface fractal dimension (Ds) for features of length scales greater than and less than 1 lm, respectively. In the basaltic andesite, Dm is approximately 2.9 and Ds is approximately 2.7. The mechanism of solute transport during weathering of this rock is diffusion. Porosity and surface area increase from 1.5%to 8.5%and 3 to 23 m2 g1 respectively in a relatively consistent trend across themm-thick plagioclase reaction front. Across this front, both fractal dimensions decrease, consistentwith development of amoremonodisperse pore networkwith smoother pore surfaces. Both changes are consistent largely with increasing connectivity of pores without significant surface roughening, as expected for transport-limited weathering. In contrast, porosity and surface area increase from 1.3% to 9.5% and 1.5 to 13 m2 g1 respectively across a many cm-thick reaction front in the

  16. Subcritical crack growth and mechanical weathering: a new consideration of how moisture influences rock erosion rates.

    NASA Astrophysics Data System (ADS)

    Eppes, Martha-Cary; Keanini, Russell; Hancock, Gregory S.

    2016-04-01

    The contributions of moisture to the mechanical aspects of rock weathering and regolith production are poorly quantified. In particular, geomorphologists have largely overlooked the role of subcritical crack growth processes in physical weathering and the fact that moisture strongly influences the rates of those processes. This influence is irrespective of the function that moisture plays in stress loading mechanisms like freezing or hydration. Here we present a simple numerical model that explores the efficacy of subcritical crack growth in granite rock subaerially exposed under a range of moisture conditions. Because most weathering-related stress loading for rocks found at, or near, Earth's surface (hereafter surface rocks) is cyclic, we modeled crack growth using a novel combination of Paris' Law and Charles' Law. This combination allowed us to apply existing empirically-derived data for the stress corrosion index of Charles' Law to fatigue cracking. For stress, we focused on the relatively straightforward case of intergranular stresses that arise during solar-induced thermal cycling by conductive heat transfer, making the assumption that such stresses represent a universal minimum weathering stress experienced by all surface rocks. Because all other tensile weathering-related stresses would be additive in the context of crack growth, however, our model can be adapted to include other stress loading mechanisms. We validated our calculations using recently published thermal-stress-induced cracking rates. Our results demonstrate that 1) weathering-induced stresses as modeled herein, and as published by others, are sufficient to propagate fractures subcritically over long timescales with or without the presence of water 2) fracture propagation rates increase exponentially with respect to moisture, specifically relative humidity 3) fracture propagation rates driven by thermal cycling are strongly dependent on the magnitude of diurnal temperature ranges and the

  17. The interactions of compressive stress and weathering in driving rock fracture.

    NASA Astrophysics Data System (ADS)

    de Vilder, Saskia; Brain, Matthew; Rosser, Nick; Vann Jones, Emma

    2016-04-01

    Weathering plays an important role in weakening a rock mass before failure. The stresses generated by failure triggering events are often an order of magnitude smaller than those required to fracture rock. The compressive stresses of the slope resulting from gravitational load are also in themselves insufficient to result in fracture. Therefore, the rock must have been weakened prior to failure. Recent studies have shown that local stress concentrations within a slope can determine the effectiveness of weathering events. Currently however, the exact impact of this is not well constrained with few studies undertaken to analyse rock weathering under stress. To address this, we report the results of a laboratory testing programme designed to assess the influence of compressive stress on the effectiveness of weathering, specifically saltwater wetting and drying. In these laboratory tests, rock cores were placed under a constant 2 MPa uniaxial compressive stress, corresponding to the approximate compressive stresses at the base of a 60 m high, near-vertical rock slope. The cores consist of moderately strong grey Staithes Siltstone (unconfined compressive stress, UCS, range of 20 - 30 MPa), found along the North Yorkshire coastline, United Kingdom. The samples were subjected to saltwater wetting and drying cycles of 6 hours, designed to mimic the submersion of a coastal cliff by the tide. Modified oedometers were used to place the samples under stress as wetting and drying occurred. We tested 4 samples which had been 'preloaded' in unconfined compression to 13.5 MPa (i.e. exceeding the crack initiation threshold but insufficient to cause fracture) to simulate the role of accumulated damage (i.e. creating a population of microcracks) in the rock slope, along with 4 samples which were not 'preloaded', and 8 samples with varying geometries to simulate the role of cliff-face topography in concentrating stress. Each test had a corresponding control sample which was not placed

  18. Field and laboratory tests on risk of slope failure due to weathering of rock materials

    NASA Astrophysics Data System (ADS)

    Qureshi, M. U.; Towhata, I.; Yamada, S.; Aziz, M.

    2009-04-01

    Authors set out the challenge to explore the mechanism of rock weathering and its effects to the geotechnical hazards. Any natural or human induced disturbances to the natural slopes speed up their weathering process. So, exploration of both disturbed and undisturbed slopes is necessary for robust understanding. Various regions in Asia were explored to experience variety of environmental and climatic conditions. Field exploration on the thickness and in-situ mechanical property was carried out by performing seismic refraction surveys, dynamic cone penetration tests and Schmidt hammer tests at various sites in Japan and Pakistan. In laboratory change in mechanical property of soft rocks due to weathering has been observed and slake durability tests were conducted on various rocks. Field exploration indicated that the thickness of weathered layer is 1 meter or its roundabouts and having S-wave velocity of 200-300 m/s. Laboratory testing differentiated the slaking potential and mechanical property degradation of various rocks. Moreover sensible correlations had been observed in thickness calculated by seismic refraction or dynamic cone penetration in field. Slake durability index showed good correlation with Schmidt hammer hardness and mechanical property. A general agreement was also observed when strength and S-wave velocities from laboratory tests were compared with the field exploration. Authors believed that the study provides the useful information on the long term prediction and assessment of landslide risk.

  19. Short Communication: Evidence for non-Gaussian distribution of rock weathering rates

    NASA Astrophysics Data System (ADS)

    Emmanuel, S.

    2015-09-01

    The weathering of rocks influences the geochemistry of the oceans, the erosion of landscapes and man-made structures, and even the global climate. Although a high degree of variance is often observed in rate measurements, little is understood about the statistical characteristics of weathering rate distributions. This preliminary study demonstrates that the weathering rates of limestone, determined from measurements of an ancient eroded limestone edifice, can exhibit highly non-Gaussian behavior. While a Gaussian model produced a poor fit with the data, an alternative model - the generalized extreme value (GEV) framework - was capable of capturing the asymmetric long-tailed distribution, in good agreement with the measured curve. Furthermore, the non-Gaussian distribution of these field rates was found to have similar characteristics to the distribution of rates measured over much smaller microscopic regions of limestone surfaces in laboratory experiments. Such similar behavior could be indicative of analogous chemical and mechanical weathering processes acting over a range of spatial and temporal scales. Moreover, highly asymmetric rate distributions with high variance could be characteristic of rates not only in carbonate rocks, but also in other rock types, suggesting that the use of a small number of measurements to determine field weathering rates may be insufficient to fully characterize the range of rates in natural systems.

  20. Acid rock drainage and rock weathering in Antarctica: important sources for iron cycling in the Southern Ocean.

    PubMed

    Dold, B; Gonzalez-Toril, E; Aguilera, A; Lopez-Pamo, E; Cisternas, M E; Bucchi, F; Amils, R

    2013-06-18

    Here we describe biogeochemical processes that lead to the generation of acid rock drainage (ARD) and rock weathering on the Antarctic landmass and describe why they are important sources of iron into the Antarctic Ocean. During three expeditions, 2009-2011, we examined three sites on the South Shetland Islands in Antarctica. Two of them displayed intensive sulfide mineralization and generated acidic (pH 3.2-4.5), iron-rich drainage waters (up to 1.78 mM Fe), which infiltrated as groundwater (as Fe(2+)) and as superficial runoff (as Fe(3+)) into the sea, the latter with the formation of schwertmannite in the sea-ice. The formation of ARD in the Antarctic was catalyzed by acid mine drainage microorganisms found in cold climates, including Acidithiobacillus ferrivorans and Thiobacillus plumbophilus. The dissolved iron (DFe) flux from rock weathering (nonmineralized control site) was calculated to be 0.45 × 10(9) g DFe yr(-1) for the nowadays 5468 km of ice-free Antarctic rock coastline which is of the same order of magnitude as glacial or aeolian input to the Southern Ocean. Additionally, the two ARD sites alone liberate 0.026 and 0.057 × 10(9) g DFe yr(-1) as point sources to the sea. The increased iron input correlates with increased phytoplankton production close to the source. This might even be enhanced in the future by a global warming scenario, and could be a process counterbalancing global warming. PMID:23682976

  1. Weathering of basaltic rocks under cold, arid conditions - Antarctica and Mars

    NASA Technical Reports Server (NTRS)

    Allen, C. C.; Conca, J.-L.

    1991-01-01

    The processes taking part in the chemical weathering of nonvesicular dolerite cobbles producing etch pits and secondary minerals including clays, under cold arid conditions of high-altitude ice-free areas of Victoria Land (Antarctica) are investigated as a possible analog to processes that produced the pitted rocks and clay minerals on Mars. Results suggest that the pits in the dolerite cobbles are formed by the dissolution of the rock by rare snow-melt water during the austral summer, followed by wind erosion of weathered material. The upper interior walls of the pits are lined with a yellow precipitate consisting of illite and quartz mixture, while the pit bottoms contain alteration products including Fe-rich clay minerals and soluble salts. A model is proposed for rock pitting on Mars analogous to that of the Antarctic dolerites.

  2. 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.

  3. In-Situ and Experimental Evidence for Acidic Weathering of Rocks and Soils on Mars

    NASA Technical Reports Server (NTRS)

    Hurowitz, J. A.; McLennan, S. M.; Tosca, N. J.; Arvidson, R. E.; Michalski, J. R.; Ming, D.; Schroeder, C.; Squyres, S. W.

    2006-01-01

    Experimental data for alteration of synthetic Martian basalts at pH=0-1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock analyses from Gusev crater are well described by the relationships apparent from low pH experimental alteration data. A model for rock surface alteration is developed which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low fluid-to-rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low-pH, low fluid to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of FeO and MgO, consistent with alteration of olivine-bearing basalt and subsequent precipitation of FeO and MgO bearing secondary minerals as the primary control on soil geochemistry.

  4. Permeability and microstructural changes due to weathering of pyroclastic rocks in Cappadocia, central Turkey

    NASA Astrophysics Data System (ADS)

    Sato, M.; Takahashi, M.; Anma, R.; Shiomi, K.

    2014-12-01

    Studies of permeability changes of rocks during weathering are important to understand the processes of geomorphological development and how they are influenced by cyclic climatic conditions. Especially volcanic tuffs and pyroclastic flow deposits are easily affected by water absorption and freezing-thawing cycle (Erguler. 2009, Çelik and Ergül 2014). Peculiar erosional landscapes of Cappadocia, central Turkey, with numerous underground cities and carved churches, that made this area a world heritage site, are consists of volcanic tuffs and pyroclastic flow deposits. Understanding permeability changes of such rocks under different conditions are thus important not only to understand fundamental processes of weathering, but also to protect the landscapes of the world heritage sites and archaeological remains. In this study, we aim to evaluate internal void structures and bulk permeability of intact and weathered pyroclastic rocks from Cappadocia using X-ray CT, mercury intrusion porosimetry data and permeability measurement method of flow pump test. Samples of pyroclastic deposits that comprise the landscapes of Rose Valley and Ihlara Valley, were collected from the corresponding strata outside of the preservation areas. Porosity and pore-size distribution for the same samples measured by mercury intrusion porosimetry, indicate that the intact samples have lower porosity than weathered samples and pore sizes were dominantly 1-10μm in calculated radii, whereas weathered samples have more micropores (smaller than 1 μm). X-ray CT images were acquired to observe internal structure of samples. Micro-fractures, probably caused by repeated expansion and contraction due to temperature changes, were observed around clast grains. The higher micropore ratio in weathered samples could be attributed to the development of the micro-farctures. We will discuss fundamental processes of weathering and geomorphological development models using these data.

  5. Rock weathering by indigenous heterotrophic bacteria of Bacillus spp. at different temperature: a laboratory experiment

    NASA Astrophysics Data System (ADS)

    Štyriaková, I.; Štyriak, I.; Oberhänsli, H.

    2012-07-01

    The bio-weathering of basalt, granite and gneiss was experimentally investigated in this study. These rock-forming minerals weathered more rapidly via the ubiquitous psychrotrophic heterotrophic bacteria . With indigenous bacteria of Bacillus spp. from sediments of Lake Baikal, we traced the degradation process of silicate minerals to understand the weathering processes occurring at the change temperature in the subsurface environment with organic input. The bacteria mediated dissolution of minerals was monitored with solution and solid chemistry, X-ray analyses as well as microscopic techniques. We determined the impact of the bacteria on the mineral surface and leaching of K, Ca, Mg, Si, Fe, and Al from silicate minerals. In the samples the release of major structural elements of silicates was used as an overall indicator of silicate mineral degradation at 4°C and 18°C from five medium exchanges over 255 days of rock bioleaching. The increase of temperature importantly affected the efficiency of Fe extraction from granite and basalt as well as Si extraction from granite and gneiss. In comparison with elemental extraction order at 4°C, Ca was substituted first by Fe or Si. It is evident that temperature influences rock microbial weathering and results in a change of elements extraction.

  6. Real-time Observations of Rock Cracking and Weather Provide Insights into Thermal Stress-Related Processes of Mechanical Weathering.

    NASA Astrophysics Data System (ADS)

    Eppes, M. C.; Magi, B. I.; Keanini, R.

    2015-12-01

    The environmental conditions (weather and/or climate) that limit or drive mechanical weathering via thermal stress are poorly understood. Here we examine acoustic emission (AE) records of rock cracking in boulders sitting on the ground in humid-temperate (~1 year of data) and semi-arid (~3 years) locations. We compare on-site average ambient daily temperature for days in which cracking occurs to the average temperatures for those dates derived from local climate records. The temperatures characterizing days on which cracking occurs is similar for both stations (range = -10 C to +30 C); where 21% and 73% of cracking occurs on hot days (> 20C) in the humid and semi-arid climates respectively while 17% and 0.1% occurs on very cold days (-8C to -3C). When days during which cracking occurs are compared to climate averages, 81% (NC) and 51% (NM) of all cracking occurs on days with absolute temperature anomalies >1, regardless of the temperature. The proportion of cracking that occurs on anomalously hot or cold days rises to 92% and 77% when the data is normalized to account for uneven sampling of the days with extreme temperatures. In order to determine to what extent this trend holds true in a more complex setting, we examined an existing 100+ year record of rock falls from Yosemite Valley. Preliminary results, although more equivocal, are consistent with the boulder cracking AE data. We examine the AE datasets in the context of our previous numerical modeling of insolation-driven thermal stress in rock and hypothesize that there is an increased potential for fracture on days with extreme temperatures because 1) thermal-stress is dependent on temperature variance from far-field and/or average rock temperatures and 2) that days with climatologically extreme air temperatures result in maximums in such variance. An implication of our results is that environments with extreme weather variability may have higher thermal breakdown rates, including certain locations today and

  7. Excavatability and the effect of weathering degree on the excavatability of rock masses: An example from Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Gurocak, Zulfu; Yalcin, Erkut

    2016-06-01

    In this study, the effect of the weathering degree on the excavatability of rock masses was investigated. The ophiolitic rock mass along the route of Komurhan Tunnel was chosen as the case study. Both laboratory and field studies were carried out for this purpose. In the first stage, the ophiolitic rock mass along the tunnel route was classified into three subzones according to the weathering degree and the ophiolitic rock masses of the each subzones were classified using the empirical excavatability classifications proposed by the different researchers. Furthermore, in-situ excavatability classes of rock masses in each zone were determined and the results were compared. The in-situ excavatability class of fresh (Zone-I) and slightly weathered (Zone-II) rock masses was determined as Blasting and that of moderately weathered (Zone-III) rock mass was determined as Very Hard/Very Difficult. As the obtained results were compared, it was found that the weathering degree has a significant effect on the excavatability and that it is more appropriate to prefer empirical classifications in the empirical determination of excavatability classes of rock masses having the same lithology by taking the weathering degree into account.

  8. Behaviour of chemical elements during weathering of pyroclastic rocks, Hong Kong.

    PubMed

    Malpas, J; Duzgoren-Aydin, N S; Aydin, A

    2001-05-01

    The behaviour of whole-rock major, trace and rare earth elements (REE) during weathering under subtropical conditions is examined along a profile developed over crystal--vitric tuffs with eutaxitic texture. The intensity of weathering within the profile varies erratically, indicating weathering processes operate over different scales. Quartz, K-feldspar, plagioclase and biotite are the main primary minerals, whereas clays, sesquioxides, sericite and chlorite are the alteration products. Kaolinite, halloysite and illite-mica are the dominant clay minerals present in significantly varying proportions. Two competing processes, namely leaching and fixation, are the main regulators of variations in mostly major and some trace element concentrations along the profile. In general, as the intensity of weathering increases, Ca, Na, K, Sr +/- Si decrease, while Fe, Ti, Al and loss of ignition (LOI) increase. Likewise, the intensity of negative Eu-anomaly decreases while the intensity of negative Ce-anomaly and the La/Lu and Sm/Nd ratios increases. In detail, however, the behaviour of chemical elements cannot be solely explained in terms of the degree of weathering. This study makes it clearly evident that the type and abundance of sesquioxides and clay minerals can significantly modify the geochemical signatures of weathering processes. PMID:11392752

  9. Weathering products of basic rocks as sorptive materials of natural radionuclides

    SciTech Connect

    Omelianenko, B.I.; Niconov, B.S.; Ryzhov, B.I.; Shikina, N.D.

    1994-06-01

    The principal requirements for employing natural minerals as buffer and backfill material in high-level waste (HLW) repositories are high sorptive properties, low water permeability, relatively high thermal conductivity, and thermostability. The major task of the buffer is to prevent the penetration of radionuclides into groundwater. The authors of this report examined weathered basic rocks from three regions of Russia in consideration as a suitable radioactive waste barrier.

  10. A modelling study on the fractionation of uranium among minerals during rock weathering

    SciTech Connect

    Ohnuki, Toshihiko; Murakami, Takashi; Yanase, Nobuyuki

    1993-12-31

    A modelling study has been carried out to understand the effect of rock alteration on the fractionation of uranium among coexisting minerals (chlorite, vermiculite, kaolinite, amorphous and crystalline iron minerals) at the Koongarra ore deposit, Australia. The model considers the chlorite weathering process, its mechanism and rate, and assumes the presence of reversible and irreversible sorption sites in the secondary minerals. The calculated uranium concentrations at the two different sites in the minerals were compared with the results of sequential extraction experiments. Good agreement between the calculated and observed uranium concentrations was obtained only when an appropriate fraction of uranium is fixed to the irreversible sorption sites of the altered clay minerals. However, a conventional K{sub d} model gave inconsistent uranium concentrations. The calculated results show that the crystalline iron minerals sorb uranium during all stages of weathering, and that the uranium fractionation among the minerals varies with time until the end of the weathering.

  11. A landscape in three biospheres: biological rock weathering in a model ecosystem

    NASA Astrophysics Data System (ADS)

    Presler, J. K.

    2012-12-01

    Biological rock weathering is the process by which life breaks down minerals into forms that are readily available for creation of an ecosystem. In order to test how microbes, plants and mycorrhizal communities interact with bedrock to initiate a primary ecosystem that will eventually lead to soil formation, we developed a modular experiment in the desert biome of Biosphere-2. In this presentation we present selected phases in the development of the experimental setup. Briefly, we aimed to replicate a large-scale primordial landscape in a closed, mesocosm system involving six carefully designed, identical chambers, each containing 48 experimental columns, 30cm long. The rocks used, i.e. basalt, rhyolite, granite and schist, represent four prevalent rock types in the natural landscape. The biotic communities are represented by combinations of rock microbial communities, plants and their associated mycorrhizae. Bacterial inoculum was optimized for each rock type. Each model was created to remain completely separated from outside influence. We expect that this experiment will provide crucial knowledge about primary interactions between rock and biota on Earth. Experimental Modules

  12. Weathering in interbedded marls and conglomerates - the 1806 Goldau rock slide

    NASA Astrophysics Data System (ADS)

    Thuro, K.; Eberhard, E.

    2003-04-01

    Despite improvements in recognition, prediction and mitigation, landslides still exact a heavy social, economical and environmental toll in Switzerland. Recent landslides experienced in the Swiss Alps demonstrate the need for a deeper understanding of the geological and physical processes leading to catastrophic slope failure. Large-scale rockslides (e.g. Randa, Sandalp, Goldau, Elm, etc.), illustrate the destructive potential of these mass movements and the need for further study to improve our comprehension of the mechanisms involved. Advances in rockslide hazard assessment and forecasting will only be made when the mechanisms responsible for the evolution of catastrophic failures are better understood. To date, the study of mass movements (including rockslides) has been largely descriptive and qualitative. Studies that do focus on some quantitative aspect of large-scale mass movements are often limited to individual mechanisms or triggering processes. Traditional treatments have pursued phenomenological based approaches where a two-dimensional slide plane is assumed or delineated from survey or air photo data, and a back analysis is performed to determine the conditions existing on the surface at failure. In other words, rock slope stability analyses have largely focused on the back-analysis of a static picture of the problem, without considering how the development of the instability evolved with time. In this paper, we aim to emphasize on the evolutionary failure processes leading to large-scale mass movements in adversely dipping bedded marls and conglomerates. Of key importance are the weathering characteristics of the marl and which tend to rapidly degrade when exposed to weathering processes. The proposed hypothesis contends that rock slope instability, in such geological environments, occurs through 3 primary processes: (1) weathering of the marls including increases in pore volume (promoting water seepage), decalcification and intact strength degradation

  13. Characterization of weathering profile in granites and volcanosedimentary rocks in West Africa under humid tropical climate conditions. Case of the Dimbokro Catchment (Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Koita, M.; Jourde, H.; Koffi, K. J. P.; da Silveira, K. S.; Biaou, A.

    2013-06-01

    In granitic rocks, various models of weathering profile have been proposed, but never for the hard rocks of West Africa. Besides, in the literature there is no description of the weathering profile in volcanosedimentrary rocks. Therefore, we propose three models describing the weathering profiles in granites, metasediments, and volcanic rocks for hard rock formations located in West Africa. For each of these models proposed for granitic and volcanosedimentary rocks of the Dimbokro catchment, vertical layered weathering profiles are described, according to the various weathering and erosion cycles (specific to West Africa) that the geological formations of the Dimbokro catchment experienced from the Eocene to the recent Quaternary period. The characterization of weathering profiles is based on: i) bedrocks and weathering profile observations at outcrop, and ii) interpretation and synthesis of geophysical data and lithologs from different boreholes. For each of the geological formations (granites, metasediments, and volcanic rocks), their related weathering profile model depicted from top to bottom comprises four separate layers: alloterite, isalterite, fissured layer, and fractured fresh basement. These weathering profiles are systematically covered by a soil layer. Though granites, metasediments and volcanic rocks of the Dimbokro catchment experience the same weathering and erosion cycles during the palaeoclimatic fluctuations from Eocene to recent Quaternary period, they exhibit differences in thickness. In granites, the weathering profile is relatively thin due to the absence of iron crust which protects weathering products against dismantling. In metasediments and volcanic rocks iron crusts develop better than in granites; in these rocks the alterite are more resistant to dismantling.

  14. Rock-moisture dynamics in a hillsope underlain with weathered and fractured argillite

    NASA Astrophysics Data System (ADS)

    Salve, R.; Rempe, D. M.; Dietrich, W.

    2012-12-01

    In order to explore the recharge process through a deep, weathered bedrock zone in a strongly seasonal rainfall environment, we document the early rainy season and annual rock-moisture dynamics along a steep Northern California hillslope underlain by a thick zone of unsaturated weathered and fractured argillite. All runoff to the channel at the base of the hillslope occurs via groundwater flow that is perched on underlying low-permeability fresh bedrock. We report the timing and depth of the first rise in moisture content in response to early winter rains and storm, seasonal, and annual moisture dynamics throughout the zone. Our measurements show that after a long summer dry season, the first rains rapidly penetrate through the soil mantle and into the underlying weathered bedrock. Large rains generate a response as deep as 6 m into the weathered bedrock within a few weeks. But within hours to days of the start of rain, the perched groundwater, at depths from 4 to 18 m below the surface, responds. The wetting advanced into the bedrock, with the groundwater response magnitude and timing differing greatly across the hillslope. We distinguish soil moisture from rock moisture (which includes both exchangeable matrix water and fracture water) and find that while the soil moisture dynamically rises and falls with each successive storm event, the rock moisture in the shallow, weathered bedrock tends to vary less after initial wet up. Surprisingly, despite the more than 1400 mm of annual water flux through the unsaturated zone, the lower portions near the water table show no moisture variation, even as the water table rises and falls with each storm pulse. These observations suggest that fracture flow plays a predominant role in transmitting water to the water table, and hence, the runoff characteristics, water chemistry, rock-moisture availability to vegetation, the hillslope stability itself is tied to this process. We present a conceptual model to explain these dynamics

  15. Life on rock. Scaling down biological weathering in a new experimental design at Biosphere-2

    NASA Astrophysics Data System (ADS)

    Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Chorover, J.; Maier, R.; Perdrial, J. N.

    2012-12-01

    Biological colonization and weathering of bedrock on Earth is a major driver of landscape and ecosystem development, its effects reaching out into other major systems such climate and geochemical cycles of elements. In order to understand how microbe-plant-mycorrhizae communities interact with bedrock in the first phases of mineral weathering we developed a novel experimental design in the Desert Biome at Biosphere-2, University of Arizona (U.S.A). This presentation will focus on the development of the experimental setup. Briefly, six enclosed modules were designed to hold 288 experimental columns that will accommodate 4 rock types and 6 biological treatments. Each module is developed on 3 levels. A lower volume, able to withstand the weight of both, rock material and the rest of the structure, accommodates the sampling elements. A middle volume, houses the experimental columns in a dark chamber. A clear, upper section forms the habitat exposed to sunlight. This volume is completely sealed form exterior and it allows a complete control of its air and water parameters. All modules are connected in parallel with a double air purification system that delivers a permanent air flow. This setup is expected to provide a model experiment, able to test important processes in the interaction rock-life at grain-to- molecular scale.

  16. Lead isotopes tracing the life cycle of a catchment: From source rock via weathering to human impact

    NASA Astrophysics Data System (ADS)

    Negrel, P. J.; Petelet-Giraud, E.; Guerrot, C.; Millot, R.

    2015-12-01

    Chemical weathering of rocks involves consumption of CO2, a greenhouse gas with a strong influence on climate. Among rocks exposed to weathering, basalt plays a major role in the carbon cycle as it is more easily weathered than other crystalline silicate rocks. This means that basalt weathering acts as a major atmospheric CO2 sink. The present study investigated the lead isotopes in rock, soil and sediment for constraining the life cycle of a catchment, covering source rocks, erosion processes and products, and anthropogenic activities. For this, we investigated the Allanche river drainage basin in the Massif Central, the largest volcanic areas in France, that offers opportunities for selected geochemical studies since it drains a single type of virtually unpolluted volcanic rock, with agricultural activity increasing downstream. Soil and sediment are derived exclusively from basalt weathering, and their chemistry, coupled to isotope tracing, should shed light on the behavior of chemical species during weathering from parental bedrock. Bedrock samples of the basin, compared to regional bedrock of the volcanic province, resulted from a complex history and multiple mantle reservoir sources and mixing. Regarding soils and sediments, comparison of Pb and Zr normalized to mobile K shows a linear evolution of weathering processes, whereby lead enrichment from atmospheric deposition is the other major contributor. Lead-isotope ratios showed that most of the lead budget in sediment and soil results from bedrock weathering with an influence of past mining and mineral processing of ores in the Massif Central, and deposition of lead-rich particles from gasoline combustion, but no lead input from agricultural activity. A classic box model was used to investigate the dynamics of sediment transfer at the catchment scale, the lead behavior in the continuum bedrock-soil-sediment and the historical evolution of anthropogenic aerosol emissions.

  17. Neutron Activation Analysis for the Demonstration of Amphibolite Rock-Weathering Activity of a Yeast

    PubMed Central

    Rades-Rohkohl, E.; Hirsch, P.; Fränzle, O.

    1979-01-01

    Neutron activation analysis was employed in a survey of weathering abilities of rock surface microorganisms. A yeast isolated from an amphibolite of a megalithic grave was found actively to concentrate, in media and in or on cells, iron and other elements when grown in the presence of ground rock. This was demonstrated by comparing a spectrum of neutron-activated amphibolite powder (particle size, 50 to 100 μm) with the spectra of neutron-activated, lyophilized yeast cells which had grown with or without amphibolite powder added to different media. The most active yeast (IFAM 1171) did not only solubilize Fe from the rock powder, but significant amounts of Co, Eu, Yb, Ca, Ba, Sc, Lu, Cr, Th, and U were also mobilized. The latter two elements occurred as natural radioactive isotopes in this amphibolite. When the yeast cells were grown with neutron-activated amphibolite, the cells contained the same elements. Furthermore, the growth medium contained Fe, Co, and Eu which had been solubilized from the amphibolite. This indicates the presence, in this yeast strain, of active rockweathering abilities as well as of uptake mechanisms for solubilized rock components. PMID:16345472

  18. The role of forest trees and their mycorrhizal fungi in carbonate rock weathering and its significance for global carbon cycling.

    PubMed

    Thorley, Rachel M S; Taylor, Lyla L; Banwart, Steve A; Leake, Jonathan R; Beerling, David J

    2015-09-01

    On million-year timescales, carbonate rock weathering exerts no net effect on atmospheric CO2 concentration. However, on timescales of decades-to-centuries, it can contribute to sequestration of anthropogenic CO2 and increase land-ocean alkalinity flux, counteracting ocean acidification. Historical evidence indicates this flux is sensitive to land use change, and recent experimental evidence suggests that trees and their associated soil microbial communities are major drivers of continental mineral weathering. Here, we review key physical and chemical mechanisms by which the symbiotic mycorrhizal fungi of forest tree roots potentially enhance carbonate rock weathering. Evidence from our ongoing field study at the UK's national pinetum confirms increased weathering of carbonate rocks by a wide range of gymnosperm and angiosperm tree species that form arbuscular (AM) or ectomycorrhizal (EM) fungal partnerships. We demonstrate that calcite-containing rock grains under EM tree species weather significantly faster than those under AM trees, an effect linked to greater soil acidification by EM trees. Weathering and corresponding alkalinity export are likely to increase with rising atmospheric CO2 and associated climate change. Our analyses suggest that strategic planting of fast-growing EM angiosperm taxa on calcite- and dolomite-rich terrain might accelerate the transient sink for atmospheric CO2 and slow rates of ocean acidification. PMID:25211602

  19. Visible and infrared properties of unaltered to weathered rocks from Precambrian granite-greenstone terrains of the West African Craton

    NASA Astrophysics Data System (ADS)

    Metelka, Václav; Baratoux, Lenka; Jessell, Mark W.; Naba, Séta

    2015-12-01

    In situ and laboratory 0.35 μm-2.5 μm spectra of rocks from a Paleoproterozoic granite-greenstone terrain along with its Neoproterozoic sedimentary cover and derived regolith materials were examined in western Burkina Faso. The reflectance spectra show the influence of typical arid to semi-arid weathering with the formation of desert varnish, iron films, and dust coatings. Fe and Mg-OH absorption features related to chlorite, amphibole, pyroxene, epidote, and biotite are observable in the mafic and intermediate meta-volcanic rocks as well as in the granodiorites and tonalites. Al-OH absorption caused by kaolinite, smectite, illite/muscovite are typical for meta-volcano-sedimentary schists, Tarkwaian-type detrital meta-sediments, sandstones of the Taoudeni basin, all of the weathered surfaces and regolith materials. Ferric and ferrous iron absorptions related to both primary rock-forming minerals and secondary weathering minerals (goethite, hematite) were observed in most of the sampled materials. The results show that although weathering alters the spectral signature of the fresh rock, indicative absorption features located in the short wave infrared region remain detectable. In addition, spectra of soils partially reflect the mineral composition of the weathered rock surfaces. The analysis of the hyperspectral data shows the potential of differentiating between the sampled surfaces. The library presents a primary database for the geological and regolith analysis of remote sensing data in West Africa.

  20. Chemical weathering of granitic rock: experiments and Pb-Li isotopes tracing

    NASA Astrophysics Data System (ADS)

    Millot, R.; Négrel, P.

    2011-12-01

    In a recent study (Négrel et al. 2010, Chem. Geol. Vol. 274) focusing on the lead geochemistry and Pb-isotope ratios of groundwaters along a small (53 km2) endoreic granitic catchment in India (Masheshwaram, Andhra Pradesh), we have shown that most of the lead in the groundwaters is of geogenic origin. Combining a weathering model and field observations, we were able to define a two-step weathering process that includes a control on the Pb-isotope ratios by accessory phases and by the main minerals from the granite in a second step of weathering. In order to go further and to better characterize water/rock interactions, we performed laboratory experiments with the two main granite bedrocks from this site. The aim of the present work is to better constrain the processes of water/rock interactions both in terms of source (dissolution of different primary minerals) and extent of weathering, by measuring Pb isotope signatures in addition with Li isotope signatures. Laboratory experiments consisted in measuring the evolution through time of major and trace elements, as well as Pb and Li isotopic compositions of a rainwater solution in equilibrium with a granite powder. Experiments were carried out at 25°C with a solution/powder mass ratio of 10 considering 15 mL of reference solution TMRAIN-95 and 1.5 g of powdered granite placed in screw-top Teflon° PFA beakers. The beakers were kept in a temperature-controlled oven, which temperature was maintained within 5% of target temperature over the total duration of the experiments. Aliquots of the solution (after filtration at 0.2 μm) in contact with the granite powder were periodically sampled (from weeks up to 2 years) and analyzed for lead and lithium isotopic compositions. The results show that a radiogenic contribution of lead is observed during the experiments, in agreement with the field observations, and that the light lithium isotope (6Li) is preferentially retained during uptake of Li into secondary minerals. The

  1. Rock Abrasion as Seen by the MSL Curiosity Rover: Insights on Physical Weathering on Mars

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Day, M. D.; Le Mouelic, S.; Martin-Torres, F. J.; Newsom, H. E.; Sullivan, R. J., Jr.; Ullan, A.; Wiens, R. C.; Zorzano, M. P.

    2014-12-01

    Mars is a dry planet, with actively blowing sand in many regions. In the absence of stable liquid water and an active hydrosphere, rates of chemical weathering are slow, such that aeolian abrasion is a dominant agent of landscape modification where sand is present and winds above threshold occur at sufficient frequency. Reflecting this activity, ventifacts, rocks that have been abraded by windborne particles, and wind-eroded outcrops, are common. They provide invaluable markers of the Martian wind record and insight into climate and landscape modification. Ventifacts are distributed along the traverse of the Mars Science Laboratory Curiosity rover. They contain one or more diagnostic features and textures: Facets, keels, basal sills, elongated pits, scallops/flutes, grooves, rock tails, and lineations. Keels at the junction of facets are sharp enough to pose a hazard MSL's wheels in some areas. Geomorphic and textural patterns on outcrops indicate retreat of windward faces. Moonlight Valley and other depressions are demarcated by undercut walls and scree boulders, with the valley interiors containing fewer rocks, most of which show evidence for significant abrasion. Together, this suggests widening and undercutting of the valley walls, and erosion of interior rocks, by windblown sand. HiRISE images do not show any dark sand dunes in the traverse so far, in contrast to the large dune field to the south that is migrating up to 2 m per year. In addition, ChemCam shows that the rock Bathurst has a rind rich in mobile elements that would be removed in an abrading environment. This indicates that rock abrasion was likely more dominant in the past, a hypothesis consistent with rapid scarp retreat as suggested by the cosmogenic noble gases in Yellowknife Bay. Ventifacts and evidence for bedrock abrasion have also been found at the Pathfinder, Spirit, and Opportunity sites, areas, like the Curiosity traverse so far, that lack evidence for current high sand fluxes. Yardangs

  2. Effects of direct and indirect heating on the validity of rock weathering simulation studies and durability tests

    NASA Astrophysics Data System (ADS)

    Warke, P. A.; Smith, B. J.

    1998-04-01

    Rock surface and subsurface temperature responses in samples exposed to direct heating (insolation) under natural hot desert conditions reveal considerable variability between lithologies related to differences in thermal properties, especially albedo and thermal conductivity. However, when the same samples are heated indirectly by air in an oven-based environmental cabinet, lithological differences in temperature response disappear and all samples attain temperatures similar to the air temperature within the cabinet. Rates and patterns of rock decay produced in such environmental cabinets may not, therefore, reflect those encountered under natural conditions, where breakdown is related to micro-environmental conditions at the rock/air interface and where rock temperature is one of the most important controlling factors. In addition to implications for assessment of weathering effectiveness, use of only indirect forms of heating affects the determination of comparative rock durability because all rock types are cycled through the same temperature regimes. Because temperature exerts such a major control on rock breakdown through its control on physical and chemical weathering processes, all significant factors influencing it must be included in the design of weathering simulations and durability tests.

  3. Evidence for Physical Weathering of Iron Meteorite Meridiani Planum (Heat Shield Rock) on Mars

    NASA Astrophysics Data System (ADS)

    Ashley, J. W.; McCoy, T. J.; Schröder, C.

    2009-12-01

    Meteorites on the surfaces of other solar system bodies can provide natural experiments for monitoring weathering processes. In the case of Mars, clues to the more subtle aspects of water occurrence and reaction may be revealed by the effects of highly sensitive aqueous alteration processes, while physical processes may be recorded through aeolian abrasion effects. Over the past 2000 sols, the two Mars Exploration Rover (MER) spacecraft have formally identified a minimum of 11 meteorite candidates [1-3], with many more unofficial candidates likely, posing an intriguing set of questions concerning their chemical, mineralogical, and morphological conditions. Five meteorite candidates, including the newly discovered MER-B rock Block Island, and one confirmed meteorite [Meridiani Planum (MP; originally Heat Shield Rock)] [4] have been investigated with the rover arm instruments. All contain levels of ferric iron, which should not be present in pristine samples (i.e. without fusion crust and/or alteration phases). Moreover, preliminary morphologic evidence contributes to the case of possible chemical weathering in Block Island. Scrutiny of a Microscopic Imager (MI) mosaic of MP shows clear evidence for both localized aeolian sculpting, and the Widmanstätten pattern common to sliced and acid-etched surfaces of many iron-nickel meteorites. These latter features are manifest as millimeter-sized chevrons and subparallel linearities, most prominent across a partially brushed surface approximately 3 x 2 cm in area. Similar patterns are observed on a number of hot and cold desert meteorites (e.g. Drum Mountain and Ft. Stockton), and are attributed to physical ablation by sand grains differentially weathering the kamacite and taenite lamellae within the rock. A similar or identical process is interpreted as responsible for the features observed in MP. Other macro-scale features on MP are of questionable weathering origin. While some prefer a regmaglypt interpretation for the

  4. A study of the depth of weathering and its relationship to the mechanical properties of near-surface rocks in the Mojave Desert

    NASA Astrophysics Data System (ADS)

    Stierman, Donald J.; Healy, John H.

    1984-03-01

    Weathered granite extends 70 m deep at Hi Vista in the arid central Mojave Desert of southern California. The low strength of this granite is due to the alteration of biotite and chlorite montmorillonite. Deep weathering probably occurs in most granites, although we cannot rule out some anomalous mechanisms at Hi Vista. Geophysical instruments set in these slightly altered rocks are limited by the unstable behavior of the rocks. Thus, tectonic signals from instruments placed in shallow boreholes give vague results. Geophysical measurements of these weathered rocks resemble measurements of granitic rocks near major faults. The rheology of the rocks in which instruments are placed limits the useful sensitivity of the instruments.

  5. Terrestrial and stream chemical linkages reveal extent of rock weathering in the perhumid coastal temperate rainforest of Alaska.

    NASA Astrophysics Data System (ADS)

    D'Amore, D. V.; Trainor, T.

    2014-12-01

    Climate influences the rate of reactions that drive material fluxes, especially the rock-water interaction within the earth's critical zone. The perhumid temperate rainforests of southeast Alaska (PCTR) are valuable sites for testing theories and applying models for ecosystem development. The landscape of the PCTR is chronologically young, but by contrast, has experienced rapid change during the Holocene due to a humid climate that promotes intense soil weathering and rapid accumulation of soil organic carbon. We investigated the magnitude of present rock-water interaction in several catchments and watersheds arrayed across a spectrum of this landscape evolution. All of the catchments had evidence of weathering as indicated by cation export relative to sea-salt aerosol input. The magnitude of the weathering signature was inversely related to the accumulation of organic carbon in the catchment. We conclude that biological processes inhibit the weathering of lithologic materials due to organic matter accumulation. However, there is clear evidence that the landscape is still actively weathering. The extent of the consumption of CO2 by rock weathering will be critical in determining long-term carbon budgets in the region and determining the sink strength of the terrestrial ecosystem. This study provides a template for examining landscape evolution in the context of critical zone science in a relatively pristine landscape.

  6. Chemical weathering on Mars - Thermodynamic stabilities of primary minerals /and their alteration products/ from mafic igneous rocks

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1978-01-01

    Chemical weathering on Mars is examined theoretically from the standpoint of thermodynamic equilibrium between primary rock-forming minerals and the atmospheric gases O2, H2O, and CO2. The primary minerals considered are those common to mafic igneous rocks and include olivine, pyroxene, plagioclase, magnetite, troilite, pyrrhotite, and apatite. The importance of kinetics and reaction mechanisms in controlling possible weathering processes on Mars is discussed within the limits of currently available data, and the possible influence of liquid water on Martian weathering processes is evaluated where appropriate. For gas-solid weathering of mafic igneous rocks at the Martian surface, it is concluded that upon attainment of thermodynamic equilibrium: (1) oxides and carbonates should dominate the mineral assemblage of weathering products; (2) hematite rather than goethite should be the stable mineral form of Fe (III); (3) FeSO4 or FeSO4.H2O could be the stable weathering product of iron sulfides in the absence of liquid water; and (4) kaolinite is apparently the only clay mineral that should be thermodynamically stable over all ranges of temperature and water-vapor abundance at the Martian surface.

  7. Controls on Weathering of Pyrrhotite in a Low-Sulfide, Granitic Mine-Waste Rock in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Langman, J. B.; Holland, S.; Sinclair, S.; Blowes, D.

    2013-12-01

    Increased environmental risk is incurred with expansion of mineral extraction in the Arctic. A greater understanding of geochemical processes associated with hard-rock mining in this cold climate is needed to evaluate and mitigate these risks. A laboratory and in-situ experiment was conducted to examine mineral weathering and the generation of acid rock drainage in a low-sulfide, run-of-mine waste rock in an Arctic climate. Rock with different concentrations of sulfides (primarily pyrrhotite [Fe7S8] containing small amounts of Co and Ni) and carbonates were weathered in the laboratory and in-situ, large-scale test piles to examine leachate composition and mineral weathering. The relatively larger sulfide-containing rock produced sufficient acid to overcome carbonate buffering and produced a declining pH environment with concomitant release of SO4, Fe, Co, and Ni. Following carbonate consumption, aluminosilicate buffering stabilized the pH above 4 until a reduction in acid generation. Results from the laboratory experiment assisted in determining that after consumption of 1.6 percent of the total sulfide, the larger sulfide-concentration test pile likely is at an internal steady-state or maximal weathering rate after seven years of precipitation input and weathering that is controlled by an annual freeze-thaw cycle. Further weathering of the test pile should be driven by external factors of temperature and precipitation in this Arctic, semi-arid region instead of internal factors of wetting and non-equilibrium buffering. It is predicted that maximal weathering will continue until at least 20 percent of the total sulfide is consumed. Using the identified evolution of sulfide consumption in this Arctic climate, a variable rate factor can now be assessed for the possible early evolution and maximal weathering of larger scale waste-rock piles and seasonal differences because of changes in the volume of a waste-rock pile undergoing active weathering due to the freeze

  8. Bacterially Induced Weathering of Ultramafic Rock and Its Implications for Phytoextraction

    PubMed Central

    Kidd, Petra; Kuffner, Melanie; Prieto-Fernández, Ángeles; Hann, Stephan; Monterroso, Carmela; Sessitsch, Angela; Wenzel, Walter; Puschenreiter, Markus

    2013-01-01

    The bioavailability of metals in soil is often cited as a limiting factor of phytoextraction (or phytomining). Bacterial metabolites, such as organic acids, siderophores, or biosurfactants, have been shown to mobilize metals, and their use to improve metal extraction has been proposed. In this study, the weathering capacities of, and Ni mobilization by, bacterial strains were evaluated. Minimal medium containing ground ultramafic rock was inoculated with either of two Arthrobacter strains: LA44 (indole acetic acid [IAA] producer) or SBA82 (siderophore producer, PO4 solubilizer, and IAA producer). Trace elements and organic compounds were determined in aliquots taken at different time intervals after inoculation. Trace metal fractionation was carried out on the remaining rock at the end of the experiment. The results suggest that the strains act upon different mineral phases. LA44 is a more efficient Ni mobilizer, apparently solubilizing Ni associated with Mn oxides, and this appeared to be related to oxalate production. SBA82 also leads to release of Ni and Mn, albeit to a much lower extent. In this case, the concurrent mobilization of Fe and Si indicates preferential weathering of Fe oxides and serpentine minerals, possibly related to the siderophore production capacity of the strain. The same bacterial strains were tested in a soil-plant system: the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain. At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots. Ni yield was significantly enhanced in plants inoculated with LA44. These results suggest that Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants. PMID:23793627

  9. Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

    SciTech Connect

    Bin Mohamad, Edy Tonnizam; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia; Saad, Rosli

    2010-12-23

    Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

  10. Geochemistry of Neogene sedimentary rocks from Borneo Basin, Malaysia: implications on paleo-weathering, provenance and tectonic setting

    NASA Astrophysics Data System (ADS)

    Ramasmay, N.; Roy, P.; MP, J.; Rufino, L.; Franz, L. K.; Viswanathan, P. M.

    2013-05-01

    Multi-element geochemistry and mineralogy are used to characterize the chemical composition, degree of paleo-weathering, provenance and tectonic settingsof the Neogene sedimentary rocks of Borneo Basin from east Malaysia. The sedimentary rocks are classified as extremely weathered sandstones (i.e. wacke, arkose, litharenite, Fe-sandstone and quartz arenite). Higher values of both weathering indices of alteration (i.e. CIA>83 and PIA>89) suggest that the sandstones have undergone extreme chemical weathering. Absence of any feldspar in the mineralogical analysis indicates its degradation during the weathering. Except for the quartz arenite, all other sandstones are characterized by post-depositional K-metasomatism and zircon enrichment through sediment recycling. The geochemical characteristics suggest a mixed-nature provenance for the sandstones with contribution coming from both felsic and mafic igneous rocks. Enriched Cr in quartz arenite and Fe-sandstone are related to contribution from ophiolite or fractionation of Cr-bearing minerals. The inferred tectonic settings are variable and suggest a complex nature of tectonic environment in the basin.

  11. Microbial populations and activities in the rhizoplane of rock-weathering desert plants. II. Growth promotion of cactus seedlings.

    PubMed

    Puente, M E; Li, C Y; Bashan, Y

    2004-09-01

    Four bacterial species isolated from the rhizoplane of cacti growing in bare lava rocks were assessed for growth promotion of giant cardon cactus seedlings (Pachycereus pringlei). These bacteria fixed N(2), dissolved P, weathered extrusive igneous rock, marble, and limestone, and significantly mobilized useful minerals, such as P, K, Mg, Mn, Fe, Cu, and Zn in rock minerals. Cardon cactus seeds inoculated with these bacteria were able to sprout and grow normally without added nutrients for at least 12 months in pulverized extrusive igneous rock (ancient lava flows) mixed with perlite. Cacti that were not inoculated grew less vigorously and some died. The amount of useful minerals (P, K, Fe, Mg) for plant growth extracted from the pulverized lava, measured after cultivation of inoculated plants, was significant. This study shows that rhizoplane bacteria isolated from rock-growing cacti promote growth of a cactus species, and can help supply essential minerals for a prolonged period of time. PMID:15375736

  12. Weather.

    ERIC Educational Resources Information Center

    Web Feet K-8, 2000

    2000-01-01

    This subject guide to weather resources includes Web sites, CD-ROMs and software, videos, books, audios, magazines, and professional resources. Related disciplines are indicated, age levels are specified, and a student activity is included. (LRW)

  13. Integrating topography, hydrology and rock structure in weathering rate models of spring watersheds

    NASA Astrophysics Data System (ADS)

    Pacheco, Fernando A. L.; Van der Weijden, Cornelis H.

    2012-03-01

    SummaryWeathering rate models designed for watersheds combine chemical data of discharging waters with morphologic and hydrologic parameters of the catchments. At the spring watershed scale, evaluation of morphologic parameters is subjective due to difficulties in conceiving the catchment geometry. Besides, when springs emerge from crystalline massifs, rock structure must be accounted in formulas describing the area of minerals exposed to the percolating fluids, for a realistic evaluation of the rates. These particular features are not included in the available approaches and for that reason a new model was developed, coined THROW model. This is a lumped approach that integrates (T)opography, (H)ydrology, (RO)ck structure and (W)eathering in a single algorithm. The study area comprises several stream watersheds and spring sites of the Vouga River basin (northern Portugal), shaped on granites. Firstly, the THROW model couples a terrain modeling analysis with hydrologic models based on discharge rates, to determine hydraulic conductivities (K), effective porosities (ne) and annual recharges (Vr) at the stream watershed scale. Subsequently, these parameters are used in a water balance model to estimate concomitant groundwater travel times (t). The mean K [(4.7 ± 3.2) × 10-7 m s-1] and ne [(2.0 ± 1.3) × 10-2] values are adopted as proxies for the spring watersheds and a firm regression equation is defined between time and stream watershed area (A). Secondly, two more runs of terrain modeling analysis are executed to extrapolate morphologic parameters for the spring watersheds. The first run hinges on scaling properties of the drainage networks, known as Horton laws, and is used to scale watershed areas across stream orders (i). The scaling function is described by another regression equation. The second run evaluates the order of a spring watershed, defined as equivalent order (ieq) and equated to the mean order of the surrounding stream watersheds. Having

  14. Erosion rates and weathering history of rock surfaces associated with Aboriginal rock art engravings (petroglyphs) on Burrup Peninsula, Western Australia, from cosmogenic nuclide measurements

    NASA Astrophysics Data System (ADS)

    Pillans, Brad; Fifield, L. Keith

    2013-06-01

    The Burrup Peninsula and surrounding Dampier Archipelago, in Western Australia, contain the world's largest known gallery of rock art engravings (petroglyphs), estimated to number up to 1 million images. The peninsula is also the site of major industrial development and there are concerns that industrial emissions may adversely affect the stability and longevity of the rock art. We have studied the natural processes and rates of weathering and erosion, including the effects of fire, that affect the stability of rock surfaces and hence the longevity of the rock art, using cosmogenic nuclides. The concentration of 10Be in quartz yields erosion rates in the range 0.15-0.48 mm/1000 years on horizontal rock surfaces and 0.34-2.30 mm/1000 years on vertical rock faces. The former, largely caused by mm-scale surface flaking, are amongst the lowest erosion rates measured by cosmogenic nuclides anywhere in the world. The latter are inferred to represent a combination of mm-scale flaking and very rare centimetre- to metre-scale block falls, controlled by failure along joint planes. Such low erosion rates result from a combination of resistant rocks, low relief and low rainfall, favouring long-term preservation of the petroglyphs - long enough to encompass the known period of human settlement in Australia.

  15. Fluoride in weathered rock aquifers of southern India: Managed Aquifer Recharge for mitigation.

    PubMed

    Brindha, K; Jagadeshan, G; Kalpana, L; Elango, L

    2016-05-01

    Climatic condition, geology, and geochemical processes in an area play a major role on groundwater quality. Impact of these on the fluoride content of groundwater was studied in three regions-part of Nalgonda district in Telangana, Pambar River basin, and Vaniyar River basin in Tamil Nadu, southern India, which experience semi-arid climate and are predominantly made of Precambrian rocks. High concentration of fluoride in groundwater above 4 mg/l was recorded. Human exposure dose for fluoride through groundwater was higher in Nalgonda than the other areas. With evaporation and rainfall being one of the major contributors for high fluoride apart from the weathering of fluoride rich minerals from rocks, the effect of increase in groundwater level on fluoride concentration was studied. This study reveals that groundwater in shallow environment of all three regions shows dilution effect due to rainfall recharge. Suitable managed aquifer recharge (MAR) methods can be adopted to dilute the fluoride rich groundwater in such regions which is explained with two case studies. However, in deep groundwater, increase in fluoride concentration with increase in groundwater level due to leaching of fluoride rich salts from the unsaturated zone was observed. Occurrence of fluoride above 1.5 mg/l was more in areas with deeper groundwater environment. Hence, practicing MAR in these regions will increase the fluoride content in groundwater and so physical or chemical treatment has to be adopted. This study brought out the fact that MAR cannot be practiced in all regions for dilution of ions in groundwater and that it is essential to analyze the fluctuation in groundwater level and the fluoride content before suggesting it as a suitable solution. Also, this study emphasizes that long-term monitoring of these factors is an important criterion for choosing the recharge areas. PMID:26822219

  16. Studies of Fe/sup 2 +/. -->. Fe/sup 3 +/ transitions during the process of rock weathering by nuclear gamma-resonance spectroscopy

    SciTech Connect

    Vasil'ev, S.P.; Babanin, V.F.; Solov'ev, A.A.

    1986-11-01

    This paper presents a method for the mineral and weathering assessment of rocks and carbonaceous matter based in gamma spectroscopy and transitions between iron ions. The method is applied to rocks collected near the Teberda preserve. Four latitudinal bands of rocks parallel to the Greater Caucasus Ridge are identified in this territory. Isomer shift and hyperfine parameters of the Moessbauer spectra are given.

  17. Characterizing the process and quantifying the rate of subaerial rock weathering on desert surfaces using roughness analysis

    NASA Astrophysics Data System (ADS)

    Mushkin, Amit; Sagy, Amir; Trabelci, Eran

    2013-04-01

    Subaerial weathering of rocks is a common process observed on desert surfaces on Earth and other planetary terrestrial surfaces such as on Mars. On Earth, this weathering process has been previously identified as one of the key erosion agent driving geomorphic surface evolution and the development of desert pavements. And yet, fundamental aspects of the process, such as the relative contribution of the different weathering modes that drive it (e.g., mechanical breakdown of rocks, chemical weathering, aeolian abrasion and exfoliation) as well as the rate by which this weathering process occurs have not been systematically examined. Here, we present a new approach for quantitatively addressing these fundamental aspects of process geomorphology on desert surfaces. We focus here on co-genetic desert alluvial surfaces of different ages, i.e. alluvial chronosequences, which provide excellent recorders for the evolution of boulder-strewn surfaces into smooth desert pavements through in-situ subaerial weathering of rocks. Our approach combines independent measures of two different surface attributes: High resolution (mm-scale) 3D ground-based laser scanning (LiDAR) of surface micro-topography, and numerical dating of surface age. Roughness analysis of the LiDAR data in power spectral density (PSD) space allows us to characterize the geometric manifestation of rock weathering on the surface and to distinguish between the different weathering modes. Numerical age constraints provide independent estimates for the time elapsed since the process began. Accordingly, we are able to constrain surface roughness evolution on alluvial fan desert chronosequences through time, and present PSD analysis of surface roughness as a new quantitative tool to examine the process of subaerial rock weathering in desert environments. In this study we present results from two late Quaternary alluvial chronosequences along the Dead Sea Transform in the hyper-arid Negev desert of southern Israel. Li

  18. Mismatched Physical and Chemical Weathering of Rocks on Mars: Clues to Past Climate

    NASA Astrophysics Data System (ADS)

    Thomson, B. J.; Hurowitz, J. A.; Baker, L. L.; Bridges, N. T.; Lennon, A.; Paulson, G.; Zacny, K.

    2014-07-01

    Here we quantify the degree of weathering experienced by the Adirondack-class basalts at the MER Spirit site by performing comparative analyses on the strength and chemistry of a series of progressively weathered Columbia River Basalt samples.

  19. Groundwater flows in weathered crystalline rocks: Impact of piezometric variations and depth-dependent fracture connectivity

    NASA Astrophysics Data System (ADS)

    Guihéneuf, N.; Boisson, A.; Bour, O.; Dewandel, B.; Perrin, J.; Dausse, A.; Viossanges, M.; Chandra, S.; Ahmed, S.; Maréchal, J. C.

    2014-04-01

    Groundwater in shallow weathered and fractured crystalline rock aquifers is often the only perennial water resource, especially in semi-arid region such as Southern India. Understanding groundwater flows in such a context is of prime importance for sustainable aquifer management. Here, we describe a detailed study of fracture properties and relate the hydraulic connectivity of fractures to groundwater flows at local and watershed scales. Investigations were carried out at a dedicated Experimental Hydrogeological Park in Andhra Pradesh (Southern India) where a large network of observation boreholes has been set up. Twenty-height boreholes have been drilled in a small area of about 18,000 m2 in which borehole loggings and hydraulic tests were carried out to locate the main flowing fractured zones and investigate fractures connectivity. Several hydraulic tests (nineteen slug tests and three pumping tests) performed under two water level conditions revealed contrasting behavior. Under high water level conditions, the interface including the bottom of the saprolite and the first flowing fractured zone in the upper part of the granite controls groundwater flows at the watershed-scale. Under low water level conditions, the aquifer is characterized by lateral compartmentalization due to a decrease in the number of flowing fractures with depth. Depending on the water level conditions, the aquifer shifts from a watershed flow system to independent local flow systems. A conceptual groundwater flow model, which includes depth-dependent fracture connectivity, is proposed to illustrate this contrasting hydrological behavior. Implications for watershed hydrology, groundwater chemistry and aquifer vulnerability are also discussed.

  20. Examining natural rock varnish and weathering rinds with laser-induced breakdown spectroscopy for application to ChemCam on Mars.

    PubMed

    Lanza, Nina L; Clegg, Samuel M; Wiens, Roger C; McInroy, Rhonda E; Newsom, Horton E; Deans, Matthew D

    2012-03-01

    A laser-induced breakdown spectroscopy (LIBS) instrument is traveling to Mars as part of ChemCam on the Mars Science Laboratory rover. Martian rocks have weathered exteriors that obscure their bulk compositions. We examine weathered rocks with LIBS in a martian atmosphere to improve interpretations of ChemCam rock analyses on Mars. Profile data are analyzed using principal component analysis, and coatings and rinds are examined using scanning electron microscopy and electron probe microanalysis. Our results show that LIBS is sensitive to minor compositional changes with depth and correctly identifies rock type even if the series of laser pulses does not penetrate to unweathered material. PMID:22410929

  1. Water-rock interaction on the development of granite gneissic weathered profiles in Garhwal Lesser Himalaya, India

    NASA Astrophysics Data System (ADS)

    Vyshnavi, S.; Islam, R.

    2015-07-01

    The development and sustainability of weathered profiles are very difficult in the Himalaya due to its complex lithology, tectonic history and fast erosion. Despite this, two weathered profiles namely WPa (weathered profile a) and WPb (weathered profile b) which have sustained erosion are developed on porphyry granite gneiss and granite gneissic lithology in Alaknanda valley of the Garhwal Lesser Himalaya. Systematic sampling of these two weathered profiles was done from bottom to top and they were chemically analysed to understand the elemental mobility in each profile. Major, trace and rare earth element studies show dissimilar behaviour with the advancement of weathering. In WPa profile, the CIA value of LAR (LAR) is 50 which reveals that the rock has not suffered any alteration but in WPb profile, the CIA value of LAR is 64 which indicates significant amount of chemical alteration. A-CN-K projection also exhibits similar behaviour. Further, the relative mobility of all the major and trace elements show variable elemental distribution in both the profiles. Enrichment of Mg, Fe, Ti, Al, Co, Ni, Zr, LREE and depletion of Na, K, P, Ca, Si, LILE and HFSE are observed in WPa profile; while the depletion of Na, K, Ca, P, Si, HREE and enhancement of Fe, Mn, Ti, Sc, Co, Zr, LREE are noticed in WPb profile. The rare earth elements also show a dissimilar mobilization pattern in both the profiles due to their strong dependency on lithology, and corresponding climate and tectonic interaction. Contrasting elemental mobility in both the profiles depict the major role in disparity of lithological characters and subsequent development of fractures produced by the major thrust system (Ramgarh thrust) which made an easy passage for rain water, thus causing the development of a chemically altered profile in the Lesser Himalayan region. Further, the present study infers the climate and tectonic milieu which is responsible for the development of such weathered profiles in Himalayan

  2. A study of the depth of weathering and its relationship to the mechanical properties of near-surface rocks in the Mojave Desert

    USGS Publications Warehouse

    Stierman, D.J.; Healy, J.H.

    1985-01-01

    Weathered granite extends 70 m deep at Hi Vista in the arid central Mojave Desert of southern California. The low strength of this granite is due to the alteration of biotite and chlorite montmorillonite. Deep weathering probably occurs in most granites, although we cannot rule out some anomalous mechanisms at Hi Vista. Geophysical instruments set in these slightly altered rocks are limited by the unstable behavior of the rocks. Thus, tectonic signals from instruments placed in shallow boreholes give vague results. Geophysical measurements of these weathered rocks resemble measurements of granitic rocks near major faults. The rheology of the rocks in which instruments are placed limits the useful sensitivity of the instruments. ?? 1985 Birkha??user Verlag.

  3. Anomalous Features on Anomalous Rocks — Deciphering the Physical Weathering History of Iron Meteorites found on Mars using Terrestrial Analogues

    NASA Astrophysics Data System (ADS)

    Ashley, J.

    2015-12-01

    Non-indigenous rocks (meteorites) found on Mars by rover science teams offer insights into probable recent (mid- to late-Amazonian) weathering processes within 15° of the martian equator. While source materials are often in question for indigenous martian alteration scenarios, the starting materials for most meteorites are known as unweathered, curated falls in Earth-based collections. Both chemical and mechanical weathering processes have modified at least 21 confirmed and candidate exogenic rocks found at three rover landing sites. Such processes have been shown to include acidic corrosion, oxide production, and aeolian scouring. The unknown martian surface exposure duration of the meteorites makes separating physical from chemical weathering effects challenging: Saltating sand grains may accomplish alone what oxidation and rust removal by aeolian scouring may accomplish in a shorter time interval, for example. However, aeolian abrasion appears to dominate for at least some of the surface features in martian irons. Iron meteorites are resistant to wind-blown sand relative to silicate rocks, but are malleable and able to preserve aeolian abrasion effects. These include 1) regmaglypts enlarged into hollows with overhanging cornices; 2) surfaces scalloped or deeply fluted by straight-line groves, and/or 3) deep 'boreholes' present across many surfaces. The flutings, boreholes, and scallops have oriented symmetry and are therefore potentially useful as paleo-wind direction indicators. Boreholes tend to be clean-edged, elliptical to round, of varying diameter, and often occur independently of local topography. Ventifacted igneous rocks found at Garnet Hill, San Gorgonio Pass, California, present features that resemble many aspects of those found in the metal masses on Mars. Though of different petrologies and mineralogies, both rock types are massive, homogeneous and unfractured, which may conceivably account for some apparent similarities in mechanical weathering

  4. Proposal of a New Parameter for the Weathering Characterization of Carbonate Flysch-Like Rock Masses: The Potential Degradation Index (PDI)

    NASA Astrophysics Data System (ADS)

    Cano, M.; Tomás, R.

    2016-07-01

    The susceptibility of clay bearing rocks to weathering (erosion and/or differential degradation) is known to influence the stability of heterogeneous slopes. However, not all of these rocks show the same behaviour, as there are considerable differences in the speed and type of weathering observed. As such, it is very important to establish relationships between behaviour quantified in a laboratory environment with that observed in the field. The slake durability test is the laboratory test most commonly used to evaluate the relationship between slaking behaviour and rock durability. However, it has a number of disadvantages; it does not account for changes in shape and size in fragments retained in the 2 mm sieve, nor does its most commonly used index (Id2) accurately reflect weathering behaviour observed in the field. The main aim of this paper is to propose a simple methodology for characterizing the weathering behaviour of carbonate lithologies that outcrop in heterogeneous rock masses (such as Flysch slopes), for use by practitioners. To this end, the Potential Degradation Index (PDI) is proposed. This is calculated using the fragment size distribution curves taken from material retained in the drum after each cycle of the slake durability test. The number of slaking cycles has also been increased to five. Through laboratory testing of 117 samples of carbonate rocks, extracted from strata in selected slopes, 6 different rock types were established based on their slaking behaviour, and corresponding to the different weathering behaviours observed in the field.

  5. Effects of Weathering at Waste Rock Dump on Water Quality Inside the Mine Wastes; A Case Study in Korea

    NASA Astrophysics Data System (ADS)

    Yim, G.; Cheong, Y.; Park, H.; Ji, S.; Lee, H.

    2008-05-01

    This study was carried out to investigate the route of acid rock drainage production and some of the important factors at the abandoned Geo-pung copper mine in Okcheon, Korea. In this research area, planting and remediation have been carried out to prevent environmental pollution, but these effects turned out to be a failure and that acid rock drainage is observed around waste rock dump and planted vegetation is dying. Currently, the slope of mine waste rock dump in the study site is about 40°. It is composed of particles with a variety of shapes, with the surface exposure to atmosphere being transformed to oxide minerals due to weathering. Since groundwater level underneath the mine wastes is directly related to rainfall, a comparative evaluation of weather records and groundwater level data obtained using on-site measuring device (CTD diver) would allow estimation of locational media-specific pattern of rainfall effect in term of infiltration flux and time of threshold impact on groundwater. Sampling and analysis of there borehole water were conducted in July and September, 2007. It was found that all of the borehole water had highly variable levels of Fe (0.4-588 mg/l), Al (8.2-41.9 mg/l), Cu (6.0-32.2 mg/l), Zn (22.2-226.7 mg/l) and other elements. Also, in general, pH of the borehole waters decreased while electric conducivity measured. Such a high variance in the water quality among different borehole water suggests that geochemical environment inside the mine wastes is largely dependent on the local variation in rainfall infiltration of waste rock dump and underneath groundwater level. Vadose zone which has vertical variation of 2-4 m is directly impacted by amount of rainfall and maintains oxidizing condition due to diffusion of oxygen carred by rainfall. Therefore, sulfide minerals within in the zone continued to be oxidized, producing acid rock drainage. To prevent production of acid rock drainage of mine waste, it is necessary to control infiltration of

  6. Rock and stone weathering at Citadel fortifications, Gozo (Malta): benefits from terrestrial laser scanning combined with conventional investigations

    NASA Astrophysics Data System (ADS)

    Tapete, D.; Gigli, G.; Mugnai, F.; Vannocci, P.; Pecchioni, E.; Morelli, S.; Fanti, R.; Casagli, N.

    2012-04-01

    Military architecture heritage is frequently built on rock masses affected by slope instability and weathering processes, which progressively undermine the foundations and cause collapses and toppling of the masonries. The latter can be also weakened by alteration of the stone surfaces, as a consequence of the interactions with the local environmental conditions. These conservation issues are emphasized for those sites, whose susceptibility to structural damages is also due to the similarity between the lithotypes constituting the geologic substratum and the construction materials. Effective solutions for the protection from such a type of phenomena can be achieved if the whole "rock mass - built heritage system" is analyzed. In this perspective, we propose a new approach for the study of the weathering processes affecting historic hilltop sites, taking benefits from the combination of terrestrial laser scanning (TLS) and conventional investigations, the latter including geotechnical and minero-petrographic analyses. In particular, the results here presented were obtained from specific tests on the fortifications of Citadel, Gozo (Malta), performed in co-operation with the Restoration Unit, Works Division, Maltese Ministry for Resources and Rural Affairs and the private company Politecnica Ingegneria e Architettura. The Citadel fortifications are built at the top of a relatively stiff and brittle limestone plate, formed by Upper Coralline Limestone (UCL) and overlying a thick Blue Clay (BC) layer. Differential weathering creates extensively fractured ledges on the cap and erosion niches in the strata beneath, thereby favouring block detachment, even rockfall events, such as the last one occurred in 2001. The locally quarried Globigerina Limestone (GL), historically employed in restoration masonries, is also exposed to alveolization and powdering, and several collapses damaged the underwalling interventions. Since the erosion pattern distribution suggested a

  7. High-Silica Rock Coatings on Mars: Constraining Secondary Silicate Mineralogy and Chemical Weathering Processes on Mars.

    NASA Astrophysics Data System (ADS)

    Kraft, M. D.; Michalski, J. R.; Sharp, T. G.

    2003-12-01

    Thermal Emission Spectrometer (TES) data have been fundamental to understanding Martian surface mineralogy. These data, however, require careful modeling based on laboratory spectroscopic measurements, and modeling of some minerals for Mars has been equivocal. Due to high degrees of spectral similarity, it is difficult to distinguishing silicate glass, clay minerals, zeolites, palagonitized glass, and other secondary products such as amorphous silica as components of surface rock spectra. Deciphering the nature of secondary mineral products on Mars is of key importance to understanding the role of water at the Martian surface over time. It is of central interest to distinguish primary glass from secondary silicate minerals, and secondary minerals from one another to better constrain the degree and mechanisms of aqueous alteration. Observations of Martian surface materials indicate some degree of atmosphere-water-rock interaction. These include nanophase ferric-iron oxides from visible/near-infrared spectroscopy, concentrated hematite deposits identified with TES, high water contents of rocks measured by the Alpha Proton X-ray Spectrometer, sulfate and halide minerals inferred from lander geochemical measurements, and carbonate minerals identified in Martian dust with TES data. Mass balance suggests that if there are oxides, salts, and carbonates there must also be secondary silicate phases present on Mars, which may be identifiable with TES. Identifying the types, distribution, and abundance (or absence) of secondary silicates will enable better constrains to be placed on Martian chemical weathering processes and the role water has played at the Martian surface. We suggest that rock coatings dominated by amorphous silica are geologically reasonable for Mars and may be consistent with TES data. Laboratory measurements of silica-coated rocks show that thin, micrometer-scale silica coatings have a substantial impact on rock spectra. Consequently, if authegenic

  8. Accelerated weathering of carbonate rocks following the 2010 forest wildfire on Mt. Carmel, Israel

    NASA Astrophysics Data System (ADS)

    Shtober-Zisu, Nurit; Tessler, Naama; Tsatskin, Alexander; Greenbaum, Noam

    2015-04-01

    Massive destruction of carbonate rocks occurred on the slopes of Mt. Carmel, during the severe forest fire in 2010. The bedrock surfaces exhibited extensive exfoliation into flakes and spalls covering up to 80%-100% of the exposed rocks; detached boulders were totally fractured or disintegrated. The fire affected six carbonate units -- various types of chalk, limestone, and dolomite. The burned flakes show a consistent tendency towards flatness, in all lithologies, as 85%-95% of the flakes were detached in the form of blades, plates, and slabs. The effects of the fire depend to a large extent on the rocks' physical properties and vary with lithology: the most severe response was found in the chalk formations which are covered by calcrete (Nari crusts). These rocks reacted by extreme exfoliation, at an average depth of 7.7 to 9.6 cm and a maximum depth of 20 cm. The flakes formed in chalk were thicker, longer, and wider than those of limestone or dolomite formations. Moreover, the chalk outcrops were exfoliated in a laminar structure, one above the other, to a depth of 10 cm and more. Their shape also tended to be blockier or rod-like. In contrast, the limestone flakes were the thinnest, with 99% of them shaped like blades and plates. Scorched and blackened faces under the upper layer of spalls provided strong evidence that chalk breakdown took place at an early stage of the fire. The extreme response of the chalks can be explained by the laminar structure of the Nari, which served as planes of weakness for the rock destruction. Three years after the fire, the rocks continue to exfoliate and break down internally. As the harder surface of the Nari was removed, the more brittle underlying chalk is exposed to erosion. If fires can obliterate boulders in a single wildfire event, it follows that wildfires may serve as limiting agents in the geomorphic evolution of slopes. However, it is difficult to estimate the frequency of high-intensity fires in the Carmel region

  9. Weathering profiles in granitoid rocks of the Sila Massif uplands, Calabria, southern Italy: New insights into their formation processes and rates

    NASA Astrophysics Data System (ADS)

    Scarciglia, Fabio; Critelli, Salvatore; Borrelli, Luigi; Coniglio, Sabrina; Muto, Francesco; Perri, Francesco

    2016-05-01

    In this paper we characterized several weathering profiles developed on granitoid rocks in the Sila Massif upland (Calabria, southern Italy), integrating detailed macro- and micromorphological observations with physico-mechanical field tests and petrographic, mineralogical and geochemical analyses. We focused our attention on the main weathering and pedogenetic processes, trying to understand apparent discrepancies between weathering grade classes based on field description and geomechanical properties, and two common weathering indices, such as the micropetrographic index (Ip) and the chemical index of alteration (CIA). Our results showed that sericite on plagioclase and biotite chloritization, that represent inherited features formed during late-stage hydrothermal alteration of granitoid rocks, may cause an overestimation of the real degree of weathering of primary mineral grains under meteoric conditions, especially in lower weathering grade classes. Moreover, the frequent identification of Fe-Mn oxides and clay coatings of illuvial origin (rather than or in addition to those formed in situ), both at the macro- and microscale, may also explain an overestimation of the weathering degree with respect to field-based classifications. Finally, some apparent inconsistencies between field geomechanical responses and chemical weathering were interpreted as related to physical weathering processes (cryoclastism and thermoclastism), that lead to rock breakdown even when chemical weathering is not well developed. Hence, our study showed that particular caution is needed for evaluating weathering grades, because traditional field and geochemical-petrographic tools may be biased by inherited hydrothermal alteration, physical weathering and illuvial processes. On the basis of chronological constraints to soil formation obtained from a 42 ka-old volcanic input (mixed to granite parent materials) detected in the soil cover of the Sila Massif upland, a first attempt to estimate

  10. Venus: chemical weathering of igneous rocks and buffering of atmospheric composition.

    PubMed

    Nozette, S; Lewis, J S

    1982-04-01

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species. PMID:17736250

  11. Venus - Chemical weathering of igneous rocks and buffering of atmospheric composition

    NASA Technical Reports Server (NTRS)

    Nozette, S.; Lewis, J. S.

    1982-01-01

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.

  12. Reach-scale evidence for feedbacks among chemical weathering, rock strength and erosion in bedrock rivers across Kohala Peninsula, Hawai'i

    NASA Astrophysics Data System (ADS)

    Murphy, B. P.; Johnson, J. P.; Gasparini, N. M.; Hancock, G. S.; Small, E. E.

    2015-12-01

    Bedrock river downcutting is usually conceptualized in terms of shear-stress dependent erosion processes, such as abrasion and plucking. Many studies of climatic control on erosion have focused on the effect of rainfall rate on discharge. However, the erodibility of bedrock can also be influenced by climate-dependent chemical weathering. We show that this mechanism can not only influence erosion patterns and rates, but also reach-scale bedrock topography. First, we present a new numerical model that describes and explores the feedbacks among chemical weathering, rock strength and erosion rate. Second, we present reach-scale field data demonstrating interactions among chemical weathering, rock strength, abrasion, and channel morphology. Across an extreme rainfall gradient on Kohala Peninsula, Hawai'i, we demonstrate that bedrock chemical weathering leads to the development of significant asymmetries in rock strength across features that are exposed to abrasion. Using a type-N Schmidt hammer, we measured the in-situ rock strength across 23 morphologic features of bedrock exposed in the stream beds of rivers, and found that upstream faces are consistently stronger, by an average of 38%, than downstream faces. Measured rock strengths suggest that the erodibilty of downstream (lee) faces may be as much as 20 times higher than corresponding upstream faces where weaker weathered material is efficiently abraded away. The asymmetrical pattern of rock strength does not necessarily lead to strongly asymmetrical morphologies, because although sediment impacts may result in more erosion on the weaker downstream face, the frequency of abrasion wear is substantially less frequent. Although the physical evidence for the chemical weathering is more frequently removed from the upstream face, these results demonstrate that, particularly in regions with higher local rainfall and weathering rates, chemical weathering induced strength reduction is a specific mechanism by which climate

  13. In search for coastal amplification of rock weathering in polar climates - pilot Schmidt hammer rock tests surveys from sheltered fjords of Svalbard and tsunami-affected coasts of Western Greenland.

    NASA Astrophysics Data System (ADS)

    Strzelecki, Matt

    2014-05-01

    Recent decade has seen the major advance in Arctic coastal geomorphology due to research progress along ice-rich permafrost coastlines of Siberia, Alaska and NW Canada. On the contrary little attention was paid to Arctic rocky coastlines and their response to the reduction of sea ice cover and increased number of storms reaching Arctic region. In this paper I present results from a pilot survey of rock resistance using Schmidt Hammer Rock Tests across rocky cliffs and shore platforms developed in: - sheltered bays of Billefjorden, Svalbard characterised by prolonged sea-ice conditions and very limited operation of wave and tidal action - Vaigat Strait and Isfjorden in W Greenland influenced by landslide-triggered tsunamis and waves induced by ice-berg roll events. The aim of a pilot study was to test the hypothesized coastal impact on the rate of rock weathering in polar climates. To do so I characterise the changes in the rock resistance on the following coastal landforms: - modern and uplifted wave-washed abrasion platforms- focusing on a relation between the degree of rock surface weathering and the distance from the shoreline as well as thickness of sediment cover on shore platform surface - modern and uplifted rocky cliffs - focusing on a relation between the degree of rock surface weathering and the distance from the shoreline as well as difference in height above the sea level and relation to rock lithology. The results present another line of argument supporting intensification of rock weathering processes in the Arctic coastal zone. This work is a contribution to the National Science Centre in Poland research project no. 2011/01/B/ST10/01553.

  14. The breath of the rocks: Lake carbon dioxide emissions from weathering processes at the global scale

    NASA Astrophysics Data System (ADS)

    Marcé, R.; Obrador, B.

    2014-12-01

    Most lakes and reservoirs are known to have surface carbon dioxide (CO2) concentrations that are supersaturated with respect to the atmosphere, and hence nearly all of them are net emitters of CO2. Global carbon emissions from lakes account for 0.06 to 0.84 Pg C year-1, a substantial amount relative to other fluxes of the continental C balance. Therefore, a proper understanding of the land carbon cycle and its sensitivity to external perturbations requires detailed knowledge of drivers of global CO2 supersaturation in lakes. CO2 supersaturation has generally been attributed to a widespread imbalance of lake net ecosystem production towards net heterotrophy, but recent findings challenge this interpretation. Here we show that an integrated perspective including lake net ecosystem production together with precipitation and dissolution of carbonate minerals and inputs of dissolved inorganic carbon from the watershed, substantially improves our understanding of the processes leading to CO2 supersaturation in lakes with alkalinity above 1 meq L-1. Our results indicate that CO2 supersaturation is independent of net ecosystem production in many lakes, and that a significant amount of the CO2 evaded through their surface is directly related to weathering processes in the watershed that supply alkalinity to surface waters. After evaluation of the worldwide distribution of alkalinity across lakes we show that CO2 emissions related to weathering processes are relevant in tropical and temperate latitudes, but negligible in boreal regions.

  15. Effect of Weathering Processes on Mineralogical and Mechanical Properties of Volcanic Rocks Used as Ballast Material for Railway Between Sabuncupinar and Kütahya in Western Turkey

    NASA Astrophysics Data System (ADS)

    Abiddin Erguler, Zeynal; Adıgüzel, Ömer; Derman, Mustafa

    2015-04-01

    Geomaterials used in engineering projects and man-made structures such as railway ballasts, buildings, historical structures, monuments and tombstones naturally weather as a result of various physico-chemical factors. Due to being long-term exposure to the anthroposphere, geomaterials used for these purposes provides important information to the researchers for understanding the effect of weathering processes on their time dependent physical, mineralogical and mechanical changes. Thus, researchers frequently can take advantage of available engineering time of man-made structures to assess weathering properties of the geomaterials used in their construction in terms of time dependent durability and stability of these structures. Considering the fact that railway ballasts produced from natural deposits of limestone, dolomite, granite, basalt etc., supply an important contribution for evaluation weathering processes, a research was carried out to determine the effect of weathering as a function of time on physical, mineralogical and mechanical properties of ballasts used for railway between Kütahya and Sabuncupınar in western Turkey. For this purpose, fresh and weathered rock samples exposed to physical and chemical weathering processes at different times were collected from quarry located in Sabuncupınar and nearby railway. This volcanic rock was previously classified as basalt based on the detailed mineralogical and geochemical analyses performed at the laboratories of the Mineral Research & Exploration General Directorate located in Ankara (Turkey). In-situ characteristics of sampling site were also investigated at different locations of quarry site by line surveying technique to describe the influence of discontinuity conditions on the weathering rate of selected rocks. Several techniques were utilized to determine time dependent deterioration in mineralogical and chemical composition of these samples for understanding their weathering rate. The porosity, water

  16. Rocks.

    ERIC Educational Resources Information Center

    Lee, Alice

    This science unit is designed for limited- and non-English speaking students in a Chinese bilingual education program. The unit covers rock material, classification, characteristics of types of rocks, and rock cycles. It is written in Chinese and simple English. At the end of the unit there is a list of main terms in both English and Chinese, and…

  17. Spatial and temporal variation of uranium in a shallow weathered rock aquifer in southern India

    NASA Astrophysics Data System (ADS)

    Brindha, K.; Elango, L.; Nair, R. N.

    2011-10-01

    Uranium occurs naturally in groundwater and surface water. The objective of this study is to understand the causes for the occurrence of uranium and its spatio-temporal variation in groundwater in a part of Nalgonda district, Andhra Pradesh, south India. Uranium deposits occur in the southeastern part of this area. Groundwater samples were collected from 44 wells every two months from March 2008 to January 2009. The samples were analyzed for pH, ORP and uranium concentration. The uranium concentration in groundwater varies from 0.2 ppb to a maximum of 68 ppb with a mean of 18.5 ppb. About 21.6% of the samples were above the drinking water limit of 30 ppb set by USEPA. The uranium concentration varied with fluctuation in groundwater level, pH and ORP. Uranium concentration in groundwater changes depending on lithology, degree of weathering and rainfall recharge.

  18. Weathering of Basaltic Rocks from the Gusev Plains up into the Columbia Hills from the Perspective of the MER Mossbauer Spectrometer

    NASA Technical Reports Server (NTRS)

    Schroeder, C.; Klingelhoefer, G.; Morris, R. V.; Rodionov, D. S.; deSouza, P. A.; Ming, D. W.; Yen, A. S.; Gellert, R.; Bell, J. F., III

    2005-01-01

    Rocks on the ejecta blanket of Bonneville crater and along Spirit s traverse over the Gusev plains towards the Columbia Hills are angular and strewn across the surface. They have a basaltic composition [1,2], and their Mossbauer spectra are dominated by an olivine doublet [1]. The ubiquitous presence of abundant olivine in rocks and in surrounding soil suggests that physical rather than chemical weathering processes currently dominate the plains at Gusev crater [1]. However, MB spectra of rocks and outcrops in the Columbia Hills suggest more aggressive alteration processes have occurred. Ascending into the hills, Spirit encountered outcrop and rocks exhibiting layered structures. Some scattered rocks at the foot of the Columbia Hills appeared "rotten" or highly altered by physical and/or chemical processes (fig. 1). Mossbauer spectra of those rocks show a decrease in olivine accompanied by an increase in the Fe-oxides magnetite, hematite, and nanophase Fe3+ -oxides (fig. 2), suggesting that chemical weathering processes in the presence of water have altered these rocks and outcrops.

  19. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

    2011-01-01

    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  20. The effects of weathering on the strength and chemistry of Columbia River Basalts and their implications for Mars Exploration Rover Rock Abrasion Tool (RAT) results

    NASA Astrophysics Data System (ADS)

    Thomson, B. J.; Hurowitz, J. A.; Baker, L. L.; Bridges, N. T.; Lennon, A. M.; Paulsen, G.; Zacny, K.

    2014-08-01

    Basalt physical properties such as compressive strength and density are directly linked to their chemistry and constitution; as weathering progresses, basalts gradually become weaker and transition from intact rock to saprolite and ultimately, to soil. Here we quantify the degree of weathering experienced by the Adirondack-class basalts at the Mars Exploration Rover Spirit site by performing comparative analyses on the strength and chemistry of a series of progressively weathered Columbia River Basalt (CRB) from western Idaho and eastern Washington. CRB samples were subjected to compressive strength tests, Rock Abrasion Tool grinds, neutron activation analysis, and inductively coupled plasma optical emission spectroscopy. Analyses of terrestrial basalts indicate linked strength-chemical changes, as expected. Weathering sufficient to induce the loss of more than 50% of some cations (including >50% of MgO and MnO as well as ∼38% of Fe2O3 and 34% of CaO) was observed to weaken these samples by as much as 50% of their original strength. In comparison with the terrestrial samples, Adirondack-class basalts are most similar to the weakest basalt samples measured in terms of compressive strength, yet they do not exhibit a commensurate amount of chemical alteration. Since fluvial and lacustrine activity in Gusev crater appears to have been limited after the emplacement of flood basalt lavas, the observed weakness is likely attributable to thin-film weathering on exposed, displaced rocks in the Gusev plains (in addition to some likely shock effects). The results indicate that Adirondack-class basalts may possess a several mm-thick weak outer rind encasing an interior that is more pristine than otherwise indicated, and also suggest that long rock residence times may be the norm.

  1. Determination of Granite Rock Massif Weathering and Cracking of Surface Layers in the Oldest Parts of Medieval Mine Depending on Used Mining Method

    NASA Astrophysics Data System (ADS)

    Lednická, Markéta; Kaláb, Zdeněk

    2016-06-01

    The paper presents the use of selected non-destructive testing methods for the purpose of specifying information on weathering and cracking of surface layers of granite rock massif in the medieval Jeroným Mine (the Czech Republic). This mine has been declared the National Heritage Site of the Czech Republic and its opening as a mining museum to the public is gradually prepared. Geological and geomechanical evaluation documents the possibility to find all kinds of weathering grades of rock massif in this mine. Two non-destructive methods have been tested, namely the measurement of ultrasonic pulse velocity and the measurement of Schmidt hammer rebound value. Field measurements were performed in two selected galleries to verify the application of such methods in specific conditions of underground spaces. Used mining method is one of the parameters later influencing cracking of rock massif. In selected galleries, two different mining methods were used which means that a part of a gallery profile was mined out by hand tools in the Middle Ages and another part of the profile was later mined out by blasting. Measurements in these galleries have enabled to analyse the influence of used mining methods on cracking of rock massif in the impaired zone, and, consequently, on ongoing weathering processes in those zones.

  2. Characterization and petrophysical properties of hydrothemally altered lacustrine volcanistic rock in Geyser Valley (Kamchatka) and its transformation by weathering

    NASA Astrophysics Data System (ADS)

    Gvozdeva, Irina; Zerkal, Oleg; Samarin, Evgeny

    2013-04-01

    smectite causes high hygroscopy of deposits. Rocks are highly porous - of 37-65%, primarily low density - 0,9-1,65 g/cm3 wave velocities - from 0.74 km/s for porous to 3.42 km/sec for dense varieties. All samples are characterized by low strength characteristics: uniaxial compressive strength - 1.2 - 21.7 MPa, uniaxial tension - 0,6-4,7 MPa. By water saturation strength decreases rapidly. Soft coefficient ranges from 0.22 to 0.57. Proving to be on the land surface as a result of slope deformation, volcanic-sedimentary hydrothermally altered rocks are destroyed quickly by precipitation and temperature fluctuations Rock turned to sand, silt and clay depending on the original composition. It was found that often weathered to clayey state tuffites inherit structural and textural features of the primary species. The composition also varies: increased content of clay minerals (to 90%), decreasing the content of zeolites (not to exceed 10%). Quartz and plagioclase form sans fraction. Physical and mechanical properties vary widely: the density of the soil increases slightly up to 1,57-1,59 g/cm3 for sands, 1,2-1,79 g/cm3 for clays, porosity of 51-52% and 49-78% respectively, moisture 22-23% and 43-98/ Clays are in a state of semi-solid to fluid. The high content of smectite determines high plastic properties. Plasticity Index varies widely from 11 to 57. Cohesion and the internal friction angle obtained from shear tests also change widely. For clayey sand grip reaches 137 kPa, internal friction angle - 17 degrees. In clay grip ranges from 13 kPa to 120 kPa, and the internal friction angle - from 11 degrees to 31 degrees. Large variation of properties of the investigated soils is explained by the inhomogeneity of volcano-sedimentary formations both vertically and laterally, varying degrees of hydrothermal alteration and of weathering, fracturing and cracks filling The obtained datas can adequately characterize the volcanic-lacustrine sediments in the valley of the Geysernaya river

  3. Interstratified vermiculite-mica in the gneiss-metapelite-serpentinite rocks at Hafafit area, Southern Eastern Desert, Egypt: From metasomatism to weathering

    NASA Astrophysics Data System (ADS)

    Harraz, H. Z.; Hamdy, M. M.

    2010-09-01

    The Hafafit vermiculite in the Southern Eastern Desert of Egypt at the contact of the metapelite and serpentinite rocks with the pegmatites and gneisses of the Hafafit uplift is the only known deposit in the Arabian-Nubian Shield (ANS) rocks of the Eastern Desert (ED). It is distinctively interstratified with mica. The mineralogy and mineral chemistry of this vermiculite at four sites (HV1, HV2, HV3 and HV4) were studied to better understand its origin, which might refers to a specific geologic setting retained to Hafafit area. The vermiculite at Hafafit forms with phlogopite, actinolite-tremolite, asbestos-anthophyllite-talc and talc zones that are arranged from pegmatite and gneisses to the metapelite and serpentinite rocks. These zones were probably formed by metasomatism that related to the intrusion of the granitoid rocks and the connected pegmatites in the upper Pan-African. The XRD and EMPA studies of the interstratified vermiculite-mica concluded that vermiculitization took place through a layer-by-layer transformation of original micas. This formed, in decreasing abundance, mixed-layer phases of biotite/vermiculite (hydrobiotite), phlogopite/vermiculite (hydrophlogopite) and chlorite/vermiculite (corrensite) and discrete phases of vermiculite, chlorite and smectite. A model is suggested, in which chemical weathering by the moving downward meteoric water led to replacement of the interlayer K, in biotite from gneiss and in phlogopite from metasomatic zones, by H 2O molecules, Fe 2+ was oxidized and (OH) - replaced O 2- forming hydrobiotite and hydrophlogopite. By more K remove, Fe was replaced by Mg with the introduction of more layers of H 2O molecules leading to formation of the vermiculite. Weathering formed corrensite mixed-layer and chlorite expandable minerals on the expense of chlorite. Formation of the incomplete smectite-like layers and Al-hydroxy interlayers (13.97 Ǻ) took place at the expense of vermiculite, replacing the Mg interlayer cations

  4. Distribution of Sc, Ta, Hf, Zr, Co, and Fe in the crust of weathering of metalliferous gabbro-norites in volodarsk-volyn rock body

    SciTech Connect

    Borisenko, L.F.; Chudinov, V.I.

    1986-09-01

    Nuclear physics methods are used to determine the Sc, Ta, Hf, Zr, Co, and Fe contents in gabbro-norites and the component minerals of these rocks, as well as in the various zones of the crusts of weathering developed on gabbro-norites. It has been established that Sc, Ta, Hf, and Zr accumulate in the kaolinite zone, but Co is partly washed out of it.

  5. Behavior of major and trace elements upon weathering of peridotites in New Caledonia : A possible site on ultramafic rocks for the Critical Zone Exploration Network (CZEN) ?

    NASA Astrophysics Data System (ADS)

    Juillot, Farid; Fandeur, D.; Fritsch, E.; Morin, G.; Ambrosi, J. P.; Olivi, L.; Cognigni, A.; Hazemann, J. L.; Proux, O.; Webb, S.; Brown, G. E., Jr.

    2010-05-01

    Ultramafic rocks cover about 1% of the continental surfaces and are related to ophiolitic bodies formed near convergent plate boundaries (Coleman, 1977). The most typical ultramafic rocks are dunite and harzburgite, which are composed of easily weatherable ferromagnesian mineral species (olivines and pyroxenes), but also of more resistant spinels (chromite and magnetite). Oceanic serpentinization of these ultramafic rocks usually lead to partial transformation of these initial mineral assemblages by forming hydrous layer silicates such as serpentine (lizardite, chrysotile and antigorite) talc, chlorite and actinolite (Malpas, 1992). It also lead to the formation of highly sheared textures, which favor meteoric weathering through preferential water flows. Compared to their crystalline rock counterpart that covers most of the continental surfaces, these ultramafic rocks mainly differ by their lower SiO2, Al2O3 and K2O contents (less than 50%, 10% and 1%, respectively) and, on the opposite, much higher MgO content (more than 18%). Moreover, they commonly have higher concentrations in FeO and other trace elements, such as Ni, Cr, Mn and Co. Weathering of these rocks is then at the origin of major geochemical anomalies on continental surfaces, especially when they occur in tropical and subtropical regions. Such conditions are encountered in New Caledonia where one third of the surface is covered with peridotites (mainly harzburgite with small amounts of dunite) obducted about 35 millions years ago during large tectonic events in the Southwest Pacific at the Late Eocene (Cluzel et al., 2001). Tropical weathering of these ultramafic rocks lead to the development of thick lateritic regoliths where almost all Mg and Si have been leached out and Fe, Mn, Ni, Cr and Co have been relatively concentrated. In these oxisols, Ni, Cr and Co can exhibit concentration up to several wt%, which make them good candidates for ore mining (New Caledonia is the third Ni producer in the world

  6. Permafrost and snow monitoring at Rothera Point (Adelaide Island, Maritime Antarctica): Implications for rock weathering in cryotic conditions

    NASA Astrophysics Data System (ADS)

    Guglielmin, Mauro; Worland, M. Roger; Baio, Fabio; Convey, Peter

    2014-11-01

    In February 2009 a new permafrost borehole was installed close to the British Antarctic Survey Station at Rothera Point, Adelaide Island (67.57195°S 68.12068°W). The borehole is situated at 31 m asl on a granodiorite knob with scattered lichen cover. The spatial variability of snow cover and of ground surface temperature (GST) is characterised through the monitoring of snow depth on 5 stakes positioned around the borehole and with thermistors placed at three different rock surfaces (A, B and C). The borehole temperature is measured by 18 thermistors placed at different depths between 0.3 and 30 m. Snow persistence is very variable both spatially and temporally with snow free days per year ranging from 13 and more than 300, and maximum snow depths varying between 0.03 and 1.42 m. This variability is the main cause of high variability in GST, that ranged between - 3.7 and - 1.5 °C. The net effect of the snow cover is a cooling of the surface. Mean annual GST, mean summer GST, and the degree days of thawing and the n-factor of thawing were always much lower at sensor A where snow persistence and depth were greater than in the other sensor locations. At sensor A the potential freeze-thaw events were negligible (0-3) and the thermal stress was at least 40% less than in the other sensor locations. The zero curtain effect at the rock surface occurred only at surface A, favouring chemical weathering over mechanical action. The active layer thickness (ALT) ranged between 0.76 and 1.40 m. ALT was directly proportional to the mean air temperature in summer, and inversely proportional to the maximum snow depth in autumn. ALT temporal variability was greater than reported at other sites at similar latitude in the Northern Hemisphere, or with the similar mean annual air temperature in Maritime Antarctica, because vegetation and a soil organic horizon are absent at the study site. Zero annual amplitude in temperature was observed at about 16 m depth, where the mean annual

  7. Petrography and geochemistry of Cretaceous to quaternary siliciclastic rocks in the Tarfaya basin, SW Morocco: implications for tectonic setting, weathering, and provenance

    NASA Astrophysics Data System (ADS)

    Ali, Sajid; Stattegger, Karl; Garbe-Schönberg, Dieter; Kuhnt, Wolfgang; Kluth, Oliver; Jabour, Haddou

    2014-01-01

    The petrography, heavy mineral analysis, major element geochemical compositions and mineral chemistry of Early Cretaceous to Miocene-Pliocene rocks, and recent sediments of the Tarfaya basin, SW Morocco, have been studied to reveal their depositional tectonic setting, weathering history, and provenance. Bulk sediment compositional and mineral chemical data suggest that these rocks were derived from heterogeneous sources in the Reguibat Shield (West African Craton) including the Mauritanides and the western Anti-Atlas, which likely form the basement in this area. The Early Cretaceous sandstones are subarkosic in composition, while the Miocene-Pliocene sandstones and the recent sediments from Wadis are generally carbonate-rich feldspathic or lithic arenites, which is also reflected in their major element geochemical compositions. The studied samples are characterized by moderate SiO2 contents and variable abundances of Al2O3, K2O, Na2O, and ferromagnesian elements. Binary tectonic discrimination diagrams demonstrate that most samples can be characterized as passive continental marginal deposits. Al2O3/Na2O ratios indicate more intense chemical weathering during the Early Cretaceous and a variable intensity of weathering during the Late Cretaceous, Early Eocene, Oligocene-Early Miocene, Miocene-Pliocene and recent times. Moreover, weathered marls of the Late Cretaceous and Miocene-Pliocene horizons also exhibit relatively low but variable intensity of chemical weathering. Our results indicate that siliciclastics of the Early Cretaceous were primarily derived from the Reguibat Shield and the Mauritanides, in the SW of the basin, whereas those of the Miocene-Pliocene had varying sources that probably included western Anti-Atlas (NE part of the basin) in addition to the Reguibat Shield and the Mauritanides.

  8. Stages of weathering mantle formation from carbonate rocks in the light of rare earth elements (REE) and Sr-Nd-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Hissler, Christophe; Stille, Peter

    2015-04-01

    Weathering mantles are widespread and include lateritic, sandy and kaolinite-rich saprolites and residuals of partially dissolved rocks. These old regolith systems have a complex history of formation and may present a polycyclic evolution due to successive geological and pedogenetic processes that affected the profile. Until now, only few studies highlighted the unusual high content of associated trace elements in weathering mantles originating from carbonate rocks, which have been poorly studied, compared to those developing on magmatic bedrocks. For instance, these enrichments can be up to five times the content of the underlying carbonate rocks. However, these studies also showed that the carbonate bedrock content only partially explains the soil enrichment for all the considered major and trace elements. Up to now, neither soil, nor saprolite formation has to our knowledge been geochemically elucidated. Therefore, the aim of this study was to examine more closely the soil forming dynamics and the relationship of the chemical soil composition to potential sources. REE distribution patterns and Sr-Nd-Pb isotope ratios have been used because they are particularly well suited to identify trace element migration, to recognize origin and mixing processes and, in addition, to decipher possible anthropogenic and/or "natural" atmosphere-derived contributions to the soil. Moreover, leaching experiments have been applied to identify mobile phases in the soil system and to yield information on the stability of trace elements and especially on their behaviour in these Fe-enriched carbonate systems. All these geochemical informations indicate that the cambisol developing on such a typical weathering mantle ("terra fusca") has been formed through weathering of a condensed Bajocian limestone-marl facies. This facies shows compared to average world carbonates important trace element enrichments. Their trace element distribution patterns are similar to those of the soil

  9. Deciphering post-Deccan weathering and erosion history of South Indian Archean rocks from cryptomelane 40Ar-39Ar dating

    NASA Astrophysics Data System (ADS)

    Bonnet, Nicolas; Arnaud, Nicolas; Beauvais, Anicet; Chardon, Dominique

    2015-04-01

    Since the extrusion of Deccan traps ~ 63 Ma ago, weathering and erosion processes have shaped the landscapes of this Peninsula India. This resulted in pervasive bauxitic weathering on traps and deep lateritic weathering of their basement on either side of the Western Ghats Escarpment, which separates a coastal lowland from an East-dipping highland plateau. Mn-rich lateritic profiles formed by supergene weathering of Late Archean manganiferous protores in the different greenstone belts are exposed on relict paleosurfaces, which are preserved at different elevations on the highland plateau and in the coastal lowland, allowing for direct comparison of paleosurfaces and geomorphological processes across one of the most prominent relief in the Indian peninsula. Detailed petrological and geochemical investigations of samples collected in the different Mn-rich lateritic profiles allowed for precise characterization of cryptomelane [Kx Mn8-xIV MnxIII O16, nH2O], a Mn-oxide suitable for 40Ar-39Ar dating. The ages obtained document major weathering periods at ~ 53-50 Ma, ~ 40-32 Ma, and ~ 30-23 Ma in the highland profiles, and ~ 47-45 Ma, ~ 24-19 Ma and a younger age at ~ 9 Ma in the coastal lowland profiles. The age clusters are in good agreement with major regional and global Cenozoic paleoclimatic events, e.g., the Eocene climatic optimum and the early beginnings of Asian monsoons at ~ 40 Ma. The old ages obtained both in the coastal lowland and high plateau indicate synchronous lateritic (mostly bauxitic) weathering on both sides of the escarpment. The ages also indicate that most of the incision and dissection of plateau landsurfaces must have taken place during successive periods after 45, 32 and 23 Ma, while the coastal lowland surface was only weakly incised after 19 Ma. Our results thus document post-Eocene divergent erosion and weathering histories across the escarpment since it was formed at least 47 Ma ago, suggesting installation of a dual climatic regime on

  10. Silica- and sulfate-bearing rock coatings in smelter areas: Products of chemical weathering and atmospheric pollution I. Formation and mineralogical composition

    NASA Astrophysics Data System (ADS)

    Mantha, Nathalie M.; Schindler, Michael; Murayama, Mitsuhiro; Hochella, Michael F.

    2012-05-01

    Black rock-coatings occur in proximity to smelters and roast yards of the Greater Sudbury area, Ontario, Canada and contain information about the past interactions between surface minerals, and gaseous and particulate atmospheric components, many of which were pollutants. Rock-coatings were collected from various locations within the Sudbury area and are characterized with scanning electron microscopy, transmission electron microscopy, X-ray diffraction, electron microprobe analysis, infrared spectroscopy and X-ray photoelectron spectroscopy. Acidic fumigations and rain, the result of vast quantities of SO2 released from smelting, increased the chemical weathering rate of exposed rocks in the Sudbury area. Non-stoichiometric dissolution of the silicate minerals under acidic conditions resulted in the accumulation of silicic acid and the subsequent formation of a silica-gel type coating. The silica gel transformed overtime into amorphous silica, opal (opal C and opal-CT) and cristobalite. Dissolution of the underlying rock and also of metal-bearing particles by sulfuric acid resulted in the in situ formation of metal-sulfate-rich layers on the interfaces between the atmosphere and the silica-rich coating (atmosphere-coating interface, ACI) and between the silica-rich coating and the underlying rock (rock-coating interface, RCI). These metal-sulfate-rich layers contain nanometer aggregates of Fe-Cu-sulfate-hydroxide, goldichite, mereiterite, guildite, butlerite and antlerite. The silica-rich matrix also contains a mix of detrital grains from adjacent rocks and soils (feldspar, quartz, hematite, chlorite, montmorillonite) and non-dissolved smelter-derived nano- to micro-size particulates (metal-silicates, metal-oxides, C-spheres). The apparent disequilibrium between the embedded particles and the Fe-Cu-sulfates suggests that trapped nanoparticles were encapsulated into pores which prevented their equilibration with acidic metal-sulfate-bearing fluids. An XPS depth

  11. Space Weathering of Apollo 16 Sample 62255: Lunar Rocks as Witness Plates for Deciphering Regolith Formation Processes

    NASA Technical Reports Server (NTRS)

    Wentworth, S. J.; McKay, D. S.; Keller, L. P.

    2004-01-01

    Space weathering, or alteration that occurs at the surfaces of materials exposed directly to space, has been one of the primary areas of focus of lunar studies for the past several years. It is caused by processes such as micrometeorite impacts and solar wind bombardment, and effects can include microcraters, spall zones, and vapor deposits. Much of the recent work on space weathering has been concentrated on nanoscale features, especially the amorphous rims commonly found on individual lunar soil grains. The rims typically contain nanophase Fe metal globules, which, along with Fe metal globules in agglutinates, have a profound effect on optical properties of lunar soils. The nanophase metallic iron globules cause the characteristic optical changes (reddening and darkening) found in mature lunar soils.

  12. Critical zone co-evolution: evidence that weathering and consequent seasonal rock moisture storage leads to a mixed forest canopy of conifer and evergreen broadleaf trees

    NASA Astrophysics Data System (ADS)

    Oshun, J.; Dietrich, W. E.; Dawson, T. E.; Rempe, D. M.; Fung, I. Y.

    2014-12-01

    Despite recent studies demonstrating the importance of rock moisture as a source of water to vegetation, much remains unknown regarding species-specific and seasonal patterns of water uptake in a Mediterranean climate. Here, we use stable isotopes of water (d18O, dD) to define the isotope composition of water throughout the subsurface critical zone of Rivendell, within the Eel River Critical Zone Observatory. We find that a structured heterogeneity of water isotope composition exists in which bulk saprolite is chronically more negative than bulk soil, and tightly held moisture is more negative than the mobile water that recharges the saturated zone and generates runoff. These moisture reservoirs provide a blueprint from which to measure the seasonal uptake patterns of different species collocated on the site. Douglas-firs use unsaturated saprolite and weathered bedrock moisture (i. e. rock moisture) throughout the year. Contrastingly, hardwood species (madrone, live oak, tanoak) modify their source water depending on which moisture is energetically favorable. Hardwoods use freely mobile water in the wet season, and rely on unsaturated zone soil moisture in the dry season. When soil water tension decreases on the drier south-facing slope, hardwood species use saprolite moisture. Although adjacent hardwoods and Douglas-firs partition water based on matric pull on the north side, there is competition for saprolite moisture in late summer on the south side. These results reveal the eco-hydrological importance of moisture derived from weathered bedrock, and show that the hardwoods have a competitive advantage under the drier conditions predicted in many climate models. Finally, the data emphasize that isotope measurements of all subsurface reservoirs and potential water sources are necessary for a complete and accurate characterization of the eco-hydrological processes within the critical zone.

  13. Characteristics of chemical weathering and water-rock interaction in Lake Nyos dam (Cameroon): Implications for vulnerability to failure and re-enforcement

    NASA Astrophysics Data System (ADS)

    Fantong, Wilson Y.; Kamtchueng, Brice T.; Yamaguchi, Kohei; Ueda, Akira; Issa; Ntchantcho, Romaric; Wirmvem, Mengnjo J.; Kusakabe, Minoru; Ohba, Takeshi; Zhang, Jing; Aka, Festus T.; Tanyileke, Gregory; Hell, Joseph V.

    2015-01-01

    For the first time, comprehensive study of hydrogeochemistry of water seeps, role of chemical weathering on dam failure, estimation of minimum width of dam to resist failure and simulation of changes in dissolved ions and secondary mineral was conducted on the Lake Nyos dam. The salient results and conclusions were; the dam spring water represented a mixture of 60-70% rainwater and 30-40% Lake water (from 0 to -40 m). The chemistry of the observed waters was Ca-HCO3 for rainwater, Ca-Mg-HCO3 in boreholes, and Mg-Ca-HCO3- for spring water. The relative rate at which ions dissolved in water was HCO3- > Mg2+ > Ca2+ > Na+ > SiO2 > K+ > NO3- > SO42- > Cl-. Weathering of rocks resulted in the formation of clay minerals such as kaolinite and smectite. Relative mobility of elements compared to Alumina (Al2O3) indicated that in monzonites there was a loss of CaO, Na2O, K2O, P2O5 and gain of SiO2, Fe2O3, TiO2, MnO and MgO, while in basalts there was a loss of SiO2, Fe2O3, Ca2O, NaO, MgO and gain of TiO2, K2O and P2O5. Values of chemical alteration index that ranged from 49 to 82 suggest a weak to intermediate categories of chemical weathering that occurred at a rate of 5.7 mm/year. Paired to that rate, which suggests that the dam is not vulnerable to failure at the previously thought time scale, some other processes (physical weathering, secondary mineral formation and lake overflow) can cause instant failure. Hydrostatic pressure of 1.6 GN generated by Lake water can be supported only when the width of the dam is greater than 19 m. PHREEQC-based simulation for 10 years indicates decoupling of Ca and Mg, and Na and Mg. Multidisciplinary monitoring of the dam is advocated.

  14. Testing the limits of micro-scale analyses of Si stable isotopes by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry with application to rock weathering

    NASA Astrophysics Data System (ADS)

    Schuessler, Jan A.; von Blanckenburg, Friedhelm

    2014-08-01

    An analytical protocol for accurate in-situ Si stable isotope analysis has been established on a new second-generation custom-built femtosecond laser ablation system. The laser was coupled to a multicollector inductively coupled plasma mass spectrometer (fsLA-MC-ICP-MS). We investigated the influence of laser parameters such as spot size, laser focussing, energy density and repetition rate, and ICP-MS operating conditions such as ICP mass load, spectral and non-spectral matrix effects, signal intensities, and data processing on precision and accuracy of Si isotope ratios. We found that stable and reproducible ICP conditions were obtained by using He as aerosol carrier gas mixed with Ar/H2O before entering the plasma. Precise δ29Si and δ30Si values (better than ± 0.23‰, 2SD) can be obtained if the area ablated is at least 50 × 50 μm; or, alternatively, for the analysis of geometric features down to the width of the laser spot (about 20 μm) if an equivalent area is covered. Larger areas can be analysed by rastering the laser beam, whereas small single spot analyses reduce the attainable precision of δ30Si to ca. ± 0.6‰, 2SD, for < 30 μm diameter spots. It was found that focussing the laser beam beneath the sample surface with energy densities between 1 and 3.8 J/cm2 yields optimal analytical conditions for all materials investigated here. Using pure quartz (NIST 8546 aka. NBS-28) as measurement standard for calibration (standard-sample-bracketing) did result in accurate and precise data of international reference materials and samples covering a wide range in chemical compositions (Si single crystal IRMM-017, basaltic glasses KL2-G, BHVO-2G and BHVO-2, andesitic glass ML3B-G, rhyolitic glass ATHO-G, diopside glass JER, soda-lime glasses NIST SRM 612 and 610, San Carlos olivine). No composition-dependent matrix effect was discernible within uncertainties of the method. The method was applied to investigate the Si isotope signature of rock weathering at

  15. Linking Weathering, Rock Moisture Dynamics, Geochemistry, Runoff, Vegetation and Atmospheric Processes through the Critical Zone: Graduate Student led Research at the Eel River Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Dietrich, W. E.

    2014-12-01

    In the Eel River Critical Zone Observatory lies Rivendell, a heavily-instrumented steep forested hillslope underlain by nearly vertically dipping argillite interbedded with sandstone. Under this convex hillslope lies "Zb", the transition to fresh bedrock, which varies from less than 6 m below the surface near the channel to 20 m at the divide. Rempe and Dietrich (2014, PNAS) show that the Zb profile can be predicted from the assumption that weathering occurs when drainage is induced in the uplifting fresh bedrock under hillslopes by lateral head gradients driven by channel incision at the hillslope boundary. Infiltrating winter precipitation is impeded at the lower conductivity boundary at Zb, generating perched groundwater that dynamically pulses water laterally to the channel, controlling stream runoff. Below the soil and above the water table lies an unsaturated zone through which all recharge to the perched groundwater (and thus all runoff to channels) occurs. It is this zone and the waters in them that profoundly affect critical zone processes. In our seasonally dry environment, the first rains penetrate past the soil and moisten the underlying weathered bedrock (Salve et al., 2012, WRR). It takes about 200 to 400 mm of cumulative rain, however, before the underlying groundwater rises significantly. Oshun et al (in review) show that by this cumulative rainfall the average of the wide-ranging isotopic signature of rain reaches a nearly constant average annual value. Consequently, the recharging perched groundwater shows only minor temporal isotopic variation. Kim et al, (2014, GCA) find that the winter high-flow groundwater chemistry is controlled by relatively fast-reacting cation exchange processes, likely occurring in transit in the unsaturated zone. Oshun also demonstrates that the Douglas fir rely on this rock moisture as a water source, while the broadleaf trees (oaks and madrone) use mostly soil moisture. Link et al (2014 WRR) show that Doug fir declines

  16. Impact of weathering on the geomechanical properties of rocks along thermal metamorphic contact belts and morpho-evolutionary processes: The deep-seated gravitational slope deformations of Mt. Granieri Salincriti (Calabria Italy)

    NASA Astrophysics Data System (ADS)

    Pellegrino, A.; Prestininzi, A.

    2007-06-01

    Numerous Deep-Seated Gravitational Slope Deformations (DSGSDs) occur throughout Italy, that originate from particular tectono-stratigraphic settings, relief, seismicity, deglaciation, as well as from intense and deep processes of chemico-physical weathering of crystalline-metamorphic rocks. These DSGSDs are particularly widespread in the Calabrian mountains. This study is focused on the Mt. Granieri-Salincriti slope, on the Ionian side of the Serre Massif, where granites and granodiorites (Stilo Unit, Palaeozoic) are in contact with metamorphites through a thermal-metamorphic aureole. This setting generates deep geochemical processes, inducing intense chemical weathering. These processes are mainly due to the interaction between groundwater and the sulphides that are contained in the local pegmatitic-hydrothermal intrusions, especially along the thermal-metamorphic contact belt. The Mt. Granieri-Salincriti slope has an important DSGSD, which is associated with many active and/or quiescent landslides. Among these landslides, the Salincriti rock avalanche-debris flow (about 2 M m 3) represents the paroxysmal and terminal stage of the deep creep deformations of Mt. Granieri, typifying a geological setting that is common in the Calabrian Arc. This multi-disciplinary study assessed the weathering susceptibility of the local crystalline-metamorphic rocks, especially those lying along thermal-metamorphic contact belts, by characterising the weathering horizons and the spatial distribution of weathering in the rock mass. The study was also aimed at identifying the relations between weathering, above all deep geochemical processes, effects on rocks and slope morphodynamics. The methodology was based on detailed geological data, geological-engineering surveys, geomorphology and surface hydrogeology analyses, as well as physico-mechanical laboratory tests. These investigations, supported by a monitoring program, led to the development of an engineering-geological model of the

  17. FTIR Spectra of Possible End Products of Martian Surface Weathering

    NASA Astrophysics Data System (ADS)

    Maxe, L. P.

    2008-03-01

    Comparative analysis of IR spectra shows that martian weathering can lead to separating destruction of surface rocks. The semi-cosmic martian weathering results in amorphous silica dust and open unique ferry aluminum/ferry silicate martian rocks.

  18. Os-Ru-Ir and Os-(Ru)-Ir-Pt mineral phases from iron quartzites and weathered rocks of the Mikhailovka and Staryi Oskol KMA iron regions, central Russia

    NASA Astrophysics Data System (ADS)

    Chernyshov, N. M.; Ponamareva, M. M.

    2015-02-01

    Numerous natural Os-Ir-Ru and Os-Ir-Ru-Pt alloys have been found in iron quartzites and their weathered rocks. The Ir-Os alloys in the Mikhailovka and Staryi Oskol KMA iron regions are characterized by the densest hexagonal packing. Almost all of them contain a low amount of Fe and Ni at a relatively higher amount of Pt, Ru, and, locally, Rh. The highest Rh contents are typical of minerals with Ir dominant over Os or with a high Pt content.

  19. Groundwater flow dynamics of weathered hard-rock aquifers under climate-change conditions: an illustrative example of numerical modeling through the equivalent porous media approach in the north-western Pyrenees (France)

    NASA Astrophysics Data System (ADS)

    Jaunat, J.; Dupuy, A.; Huneau, F.; Celle-Jeanton, H.; Le Coustumer, P.

    2016-04-01

    A numerical groundwater model of the weathered crystalline aquifer of Ursuya (a major water source for the north-western Pyrenees region, south-western France) has been computed based on monitoring of hydrological, hydrodynamic and meteorological parameters over 3 years. The equivalent porous media model was used to simulate groundwater flow in the different layers of the weathered profile: from surface to depth, the weathered layer (5 · 10-8 ≤ K ≤ 5 · 10-7 m s-1), the transition layer (7 · 10-8 ≤ K ≤ 1 · 10-5 m s-1, the highest values being along major discontinuities), two fissured layers (3.5 · 10-8 ≤ K ≤ 5 · 10-4 m s-1, depending on weathering profile conditions and on the existence of active fractures), and the hard-rock basement simulated with a negligible hydraulic conductivity (K = 1 10 -9 ). Hydrodynamic properties of these five calculation layers demonstrate both the impact of the weathering degree and of the discontinuities on the groundwater flow. The great agreement between simulated and observed hydraulic conditions allowed for validation of the methodology and its proposed use for application on analogous aquifers. With the aim of long-term management of this strategic aquifer, the model was then used to evaluate the impact of climate change on the groundwater resource. The simulations performed according to the most pessimistic climatic scenario until 2050 show a low sensitivity of the aquifer. The decreasing trend of the natural discharge is estimated at about -360 m3 y-1 for recharge decreasing at about -5.6 mm y-1 (0.8 % of annual recharge).

  20. Weather Watch

    ERIC Educational Resources Information Center

    Bratt, Herschell Marvin

    1973-01-01

    Suggests a number of ways in which Federal Aviation Agency weather report printouts can be used in teaching the weather section of meteorology. These weather sequence reports can be obtained free of charge at most major airports. (JR)

  1. Severe Weather

    ERIC Educational Resources Information Center

    Forde, Evan B.

    2004-01-01

    Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This article deals with a poster entitled, "Severe Weather," that has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in…

  2. Severe Weather

    ERIC Educational Resources Information Center

    Forde, Evan B.

    2004-01-01

    Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This month's insert, Severe Weather, has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in this poster are hurricanes,…

  3. Weather & Weather Maps. Teacher's Manual.

    ERIC Educational Resources Information Center

    Metro, Peter M.; Green, Rachel E.

    This guide is intended to provide an opportunity for students to work with weather symbols used for reporting weather. Also included are exercises in location of United States cities by latitude and longitude, measurement of distances in miles and kilometers, and prediction of weather associated with various types of weather fronts. (RE)

  4. Soil Genesis and Development, Lesson 1 - Rocks and Minerals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    All soil ultimately forms from rocks or their weathering products. Geologists classify rocks according to their origins. General rock types can weather to give soils with distinctive properties. The objectives of this lesson are: 1. To be able to classify rocks based on visual characteristics accord...

  5. Weathering and weathering rates of natural stone

    SciTech Connect

    Winkler, E.M. )

    1987-01-01

    Physical and chemical weathering were studied as separate processes in the past. Recent research, however, shows that most processes are physicochemical in nature. The rates at which calcite and silica weather by dissolution are dependent on the regional and local climatic environment. The weathering of silicate rocks leaves discolored margins and rinds, a function of the ricks permeability and of the climatic parameters. Salt action, the greatest disruptive factor, is complex and not yet fully understood in all its phases, but some of th causes of disruption are crystallization pressure, hydration pressure, and hygroscopic attraction of excess moisture. The decay of marble is complex, an interaction between dissolution, crack-corrosion, and the expansion-contraction cycles triggered by the release of residual stresses. Thin spalls of granites commonly found near the street level of buildings are generally caused by a combination of stress relief and salt action. To study and determine weathering rates of a variety of commercial stones, the National Bureau of Standards erected a Stone Exposure Test Wall in 1948. Of the many types of stone represented, only a few fossiliferous limestones permit a valid measurement of surface reduction in a polluted urban environment.

  6. Carbon dioxide efficiency of terrestrial enhanced weathering.

    PubMed

    Moosdorf, Nils; Renforth, Phil; Hartmann, Jens

    2014-05-01

    Terrestrial enhanced weathering, the spreading of ultramafic silicate rock flour to enhance natural weathering rates, has been suggested as part of a strategy to reduce global atmospheric CO2 levels. We budget potential CO2 sequestration against associated CO2 emissions to assess the net CO2 removal of terrestrial enhanced weathering. We combine global spatial data sets of potential source rocks, transport networks, and application areas with associated CO2 emissions in optimistic and pessimistic scenarios. The results show that the choice of source rocks and material comminution technique dominate the CO2 efficiency of enhanced weathering. CO2 emissions from transport amount to on average 0.5-3% of potentially sequestered CO2. The emissions of material mining and application are negligible. After accounting for all emissions, 0.5-1.0 t CO2 can be sequestered on average per tonne of rock, translating into a unit cost from 1.6 to 9.9 GJ per tonne CO2 sequestered by enhanced weathering. However, to control or reduce atmospheric CO2 concentrations substantially with enhanced weathering would require very large amounts of rock. Before enhanced weathering could be applied on large scales, more research is needed to assess weathering rates, potential side effects, social acceptability, and mechanisms of governance. PMID:24597739

  7. Weather Instruments.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities to measure various weather phenomena. Directions for constructing a weather station are included. Instruments including rain gauges, thermometers, wind vanes, wind speed devices, humidity devices, barometers, atmospheric observations, a dustfall jar, sticky-tape can, detection of gases in the air, and pH of…

  8. Wacky Weather

    ERIC Educational Resources Information Center

    Sabarre, Amy; Gulino, Jacqueline

    2013-01-01

    What do a leaf blower, water hose, fan, and ice cubes have in common? Ask the students who participated in an integrative science, technology, engineering, and mathematics (I-STEM) education unit, "Wacky Weather," and they will tell say "fun and severe weather"--words one might not have expected! The purpose of the unit…

  9. Space Weather

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis L.

    2010-01-01

    This video provides a narrated exploration of the history and affects of space weather. It includes information the earth's magnetic field, solar radiation, magnetic storms, and how solar winds affect electronics on earth, with specific information on how space weather affects space exploration in the future.

  10. Natural Weathering Rates of Silicate Minerals

    NASA Astrophysics Data System (ADS)

    White, A. F.

    2003-12-01

    Silicates constitute more than 90% of the rocks exposed at Earth's land surface (Garrels and Mackenzie, 1971). Most primary minerals comprising these rocks are thermodynamically unstable at surface pressure/temperature conditions and are therefore susceptible to chemical weathering. Such weathering has long been of interest in the natural sciences. Hartt (1853) correctly attributed chemical weathering to "the efficacy of water containing carbonic acid in promoting the decomposition of igneous rocks." Antecedent to the recent interest in the role of vegetation on chemical weathering, Belt (1874) observed that the most intense weathering of rocks in tropical Nicaragua was confined to forested regions. He attributed this effect to "the percolation through rocks of rain water charged with a little acid from decomposing vegetation." Chamberlin (1899) proposed that the enhanced rates of chemical weathering associated with major mountain building episodes in Earth's history resulted in a drawdown of atmospheric CO2 that led to periods of global cooling. Many of the major characteristics of chemical weathering had been described when Merrill (1906) published the groundbreaking volume Rocks, Rock Weathering, and Soils.The major advances since that time, particularly during the last several decades, have centered on understanding the fundamental chemical, hydrologic, and biologic processes that control weathering and in establishing quantitative weathering rates. This research has been driven by the importance of chemical weathering to a number environmentally and economically important issues. Undoubtedly, the most significant aspect of chemical weathering is the breakdown of rocks to form soils, a process that makes life possible on the surface of the Earth. The availability of many soil macronutrients such as magnesium, calcium, potassium, and PO4 is directly related to the rate at which primary minerals weather. Often such nutrient balances are upset by anthropogenic

  11. Three classes of Martian rocks

    NASA Technical Reports Server (NTRS)

    1997-01-01

    In this portion of the 360-degree color gallery pan, looking to the northeast, the colors have been exaggerated to highlight the differences between rocks and soils. Visible are the downwind sides of rocks, not exposed to wind scouring like Barnacle Bill (which faces upwind). There is a close correspondence between the shapes and colors of the rocks. Three general classes of rocks are recognized: large rounded rocks with weathered coatings, small gray angular rocks lacking weathered coatings, and flat white rocks. The large rounded rocks in the distance, marked by the red arrows, are comparable to Yogi. Spectral properties show that these rocks have a highly weathered coating in addition to a distinctive shape. A second population of smaller, angular rocks (blue arrows) in the foreground have unweathered surfaces even on the downwind side, except where covered on their tops by drift. These are comparable to Barnacle Bill. They may have been emplaced at the site relatively recently, perhaps as ejecta from an impact crater, so they have not had time to weather as extensively as the larger older rocks. The third kind of rock (white arrows) is white and flat, and includes Scooby Doo in the foreground and a large deposit in the background called Baker's Bank. The age of the white rock relative to the other two classes is still being debated. One representative rock of each class (Yogi, Barnacle Bill, and Scooby Doo) has been measured by the rover.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech).

  12. Weatherizing America

    ScienceCinema

    Stewart, Zachary; Bergeron, T.J.; Barth, Dale; Qualis, Xavier; Sewall, Travis; Fransen, Richard; Gill, Tony;

    2013-05-29

    As Recovery Act money arrives to expand home weatherization programs across the country, Zachary Stewart of Phoenix, Ariz., and others have found an exciting opportunity not only to start working again, but also to find a calling.

  13. Weatherizing America

    SciTech Connect

    Stewart, Zachary; Bergeron, T.J.; Barth, Dale; Qualis, Xavier; Sewall, Travis; Fransen, Richard; Gill, Tony

    2009-01-01

    As Recovery Act money arrives to expand home weatherization programs across the country, Zachary Stewart of Phoenix, Ariz., and others have found an exciting opportunity not only to start working again, but also to find a calling.

  14. Temperature dependence of basalt weathering

    NASA Astrophysics Data System (ADS)

    Li, Gaojun; Hartmann, Jens; Derry, Louis A.; West, A. Joshua; You, Chen-Feng; Long, Xiaoyong; Zhan, Tao; Li, Laifeng; Li, Gen; Qiu, Wenhong; Li, Tao; Liu, Lianwen; Chen, Yang; Ji, Junfeng; Zhao, Liang; Chen, Jun

    2016-06-01

    The homeostatic balance of Earth's long-term carbon cycle and the equable state of Earth's climate are maintained by negative feedbacks between the levels of atmospheric CO2 and the chemical weathering rate of silicate rocks. Though clearly demonstrated by well-controlled laboratory dissolution experiments, the temperature dependence of silicate weathering rates, hypothesized to play a central role in these weathering feedbacks, has been difficult to quantify clearly in natural settings at landscape scale. By compiling data from basaltic catchments worldwide and considering only inactive volcanic fields (IVFs), here we show that the rate of CO2 consumption associated with the weathering of basaltic rocks is strongly correlated with mean annual temperature (MAT) as predicted by chemical kinetics. Relations between temperature and CO2 consumption rate for active volcanic fields (AVFs) are complicated by other factors such as eruption age, hydrothermal activity, and hydrological complexities. On the basis of this updated data compilation we are not able to distinguish whether or not there is a significant runoff control on basalt weathering rates. Nonetheless, the simple temperature control as observed in this global dataset implies that basalt weathering could be an effective mechanism for Earth to modulate long-term carbon cycle perturbations.

  15. Where fast weathering creates thin regolith and slow weathering creates thick regolith

    SciTech Connect

    Bazilevskaya, Ekaterina; Lebedeva, Marina; Pavich, Milan; Rother, Gernot; Parkinson, D. Y.; Cole, David; Brantley, S. L.

    2012-01-01

    Weathering disaggregates rock into regolith the fractured or granular earthmaterial that sustains life on the continental land surface. Here, we investigate what controls the depth of regolith formed on ridges of two rock compositions with similar initial porosities in Virginia (USA).A priori, we predicted that the regolith on diabasewould be thicker than on granite because the dominant mineral (feldspar) in the diabase weathers faster than its granitic counterpart. However, weathering advanced 20deeper into the granite than the diabase. The 20-thicker regolith is attributed mainly to connected micron-sized pores, microfractures formed around oxidizing biotite at 20m depth, and the lower iron (Fe) content in the felsic rock. Such porosity allows pervasive advection and deep oxidation in the granite. These observations may explainwhy regolithworldwide is thicker on felsic compared tomafic rock under similar conditions. To understand regolith formationwill require better understanding of such deep oxidation reactions and how they impact fluid flow during weathering.

  16. Tithonium Chasma's Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-565, 5 December 2003

    Exposures of light-toned, layered, sedimentary rocks are common in the deep troughs of the Valles Marineris system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from western Tithonium Chasma. The banding seen here is an eroded expression of layered rock. Sedimentary rocks can be composed of (1) the detritus of older, eroded and weathered rocks, (2) grains produced by explosive volcanism (tephra, also known as volcanic ash), or (3) minerals that were chemically precipitated out of a body of liquid such as water. These outcrops are located near 4.8oS, 89.7oW. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.

  17. Weather control

    SciTech Connect

    Leepson, M.

    1980-09-05

    Weather modification, the intentional altering of atmospheric conditions to suit the purposes of humankind, has five basic forms: (1) fog dissipation; (2) rain and snow enhancement; (3) hail suppression; (4) lightning suppression; and (5) the abatement of severe storms such as hurricanes and tornadoes. The dissipation of fog and the seeding of clouds with dry ice or silver iodide to produce rain are the most successful weather modification techniques. Both are used extensively and with varying degrees of success in the United States and around the world. Cloud seeding, though, is not effective in easing the harshness of a drought, such as the one that hit the Southwest, Midwest and Great Plains this summer.

  18. Talking Rocks.

    ERIC Educational Resources Information Center

    Rice, Dale; Corley, Brenda

    1987-01-01

    Discusses some of the ways that rocks can be used to enhance children's creativity and their interest in science. Suggests the creation of a dramatic production involving rocks. Includes basic information on sedimentary, igneous, and metamorphic rocks. (TW)

  19. National Weather Service

    MedlinePlus

    ... Lightning Safe Boating Rip Currents Thunderstorms and Tornadoes Space Weather Sun (Ultraviolet Radiation) Safety Campaigns Wind Drought ... Outlook Hurricanes Fire Weather Outlooks UV Alerts Drought Space Weather NOAA Weather Radio NWS CAP Feeds PAST ...

  20. Weathering: methods and techniques to measure

    NASA Astrophysics Data System (ADS)

    Lopez-Arce, P.; Zornoza-Indart, A.; Alvarez de Buergo, M.; Fort, R.

    2012-04-01

    Surface recession takes place when weathered material is removed from the rocks. In order to know how fast does weathering and erosion occur, a review of several methods, analyses and destructive and non-destructive techniques to measure weathering of rocks caused by physico-chemical changes that occur in bedrocks due to salt crystallization, freezing-thaw, thermal shock, influence of water, wind, temperature or any type of environmental agent leading to weathering processes and development of soils, in-situ in the field or through experimental works in the laboratory are addressed. From micro-scale to macro-scale, from the surface down to more in depth, several case studies on in-situ monitoring of quantification of decay on soils and rocks from natural landscapes (mountains, cliffs, caves, etc) or from urban environment (foundations or facades of buildings, retaining walls, etc) or laboratory experimental works, such as artificial accelerated ageing tests (a.a.e.e.) or durability tests -in which one or more than one weathering agents are selected to assess the material behaviour in time and in a cyclic way- performed on specimens of these materials are summarised. Discoloration, structural alteration, precipitation of weathering products (mass transfer), and surface recession (mass loss) are all products of weathering processes. Destructive (SEM-EDX, optical microscopy, mercury intrusion porosimetry, drilling resistance measurement, flexural and compression strength) and Non-destructive (spectrophotocolorimetry, 3D optical surface roughness, Schmidt hammer rebound tester, ultrasound velocity propagation, Nuclear Magnetic Resonance NMR, X ray computed micro-tomography or CT-scan, geo-radar differential global positioning systems) techniques and characterization analyses (e.g. water absorption, permeability, open porosity or porosity accessible to water) to assess their morphological, physico-chemical, mechanical and hydric weathering; consolidation products or

  1. Lateral Variations in Lunar Weathering Patina on Centimeter to Nanometer Scales

    NASA Technical Reports Server (NTRS)

    Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

    2013-01-01

    All materials exposed at the lunar surface undergo space weathering processes. On the Moon, boulders make up only a small percentage of the exposed surface, and areas where such rocks are exposed, like central peaks, are often among the least space weathered regions identified from remote sensing data. Yet space weathered surfaces (patina) are relatively common on returned rock samples, some of which directly sample the surface of larger boulders. Because, as witness plates to lunar space weathering, rocks and boulders experience longer exposure times compared to lunar soil grains, they allow us to develop a deeper perspective on the relative importance of various weathering processes as a function of time.

  2. Weathering of Stone Monuments in Cities: A Student Exercise.

    ERIC Educational Resources Information Center

    Dragovich, D.

    1980-01-01

    Describes a college-level geography project for students limited to urban areas. Students investigate the rock-weathering process through library resources, then observe, collect, and analyze data about stone monuments. An individually written report concludes the project. (KC)

  3. Winter Weather Checklists

    MedlinePlus

    ... Planning Information on Specific Types of Emergencies Winter Weather Checklists Language: English Español (Spanish) Recommend on Facebook ... emergency instructions National Oceanic and Atmospheric Administration (NOAA) weather radio receiver for listening to National Weather Service ...

  4. Weather in the News.

    ERIC Educational Resources Information Center

    Markle, Sandra

    1989-01-01

    A discussion of TV weather forecasting introduces this article which features several hands-on science activities involving observing, researching, and experimenting with the weather. A reproducible worksheet on the reliability of weather forecasts is included. (IAH)

  5. Forecasting the Weather.

    ERIC Educational Resources Information Center

    Bollinger, Richard

    1984-01-01

    Presents a computer program which predicts the weather based on student input of such weather data as wind direction and barometric pressure. Also provides procedures for several hands-on, weather-related activities. (JN)

  6. Rock Art

    ERIC Educational Resources Information Center

    Henn, Cynthia A.

    2004-01-01

    There are many interpretations for the symbols that are seen in rock art, but no decoding key has ever been discovered. This article describes one classroom's experiences with a lesson on rock art--making their rock art and developing their own personal symbols. This lesson allowed for creativity, while giving an opportunity for integration…

  7. Rock Finding

    ERIC Educational Resources Information Center

    Rommel-Esham, Katie; Constable, Susan D.

    2006-01-01

    In this article, the authors discuss a literature-based activity that helps students discover the importance of making detailed observations. In an inspiring children's classic book, "Everybody Needs a Rock" by Byrd Baylor (1974), the author invites readers to go "rock finding," laying out 10 rules for finding a "perfect" rock. In this way, the…

  8. Collecting Rocks.

    ERIC Educational Resources Information Center

    Barker, Rachel M.

    One of a series of general interest publications on science topics, the booklet provides those interested in rock collecting with a nontechnical introduction to the subject. Following a section examining the nature and formation of igneous, sedimentary, and metamorphic rocks, the booklet gives suggestions for starting a rock collection and using…

  9. Rock Pore Structure as Main Reason of Rock Deterioration

    NASA Astrophysics Data System (ADS)

    Ondrášik, Martin; Kopecký, Miloslav

    2014-03-01

    Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite. However, rock as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if rock with unsuitable rock properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the rock deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of rocks and stones in building industry. Only after 1989 the absorption was accepted as merely informational rock property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and rock deterioration, but more or less good experiences with some high porous rocks used in constructions exposed to severe weather conditions and proving a lack of relationship between rock freeze-thaw resistivity and water absorption. Results of the recent worldwide research suggest that understanding a resistivity of rocks against deterioration is hidden not in the absorption but in the structure of rock pores in relation to thermodynamic properties of pore water and tensile strength of rocks and rock minerals. Also this article presents some results of research on rock deterioration and pore structure performed on 88 rock samples. The results divide the rocks tested into two groups - group N in which the pore water does not freeze

  10. Soil Genesis and Development, Lesson 2 - Processes of Weathering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weathering processes — which include physical, chemical, and biological — contribute to the development of soil. The learning objectives of the lesson are: 1) Define and distinguish physical, chemical, and biological weathering processes; and 2) Describe how rock and mineral properties and environm...

  11. Correlation of Rock Spectra with Quantitative Morphologic Indices: Evidence for a Single Rock Type at the Mars Pathfinder Landing Site

    NASA Technical Reports Server (NTRS)

    Yingst, R. A.; Biedermann, K. L.; Pierre, N. M.; Haldemann, A. F. C.; Johnson, J. R.

    2005-01-01

    The Mars Pathfinder (MPF) landing site was predicted to contain a broad sampling of rock types varying in mineralogical, physical, mechanical and geochemical characteristics. Although rocks have been divided into several spectral categories based on Imager for Mars Pathfinder (IMP) visible/near-infrared data, efforts in isolating and classifying spectral units among MPF rocks and soils have met with varying degrees of success, as many factors influencing spectral signatures cannot be quantified to a sufficient level to be removed. It has not been fully determined which spectral categories stem from intrinsic mineralogical differences between rocks or rock surfaces, and which result from factors such as physical or chemical weathering. This has made isolation of unique rock mineralogies difficult. Morphology, like composition, is a characteristic tied to the intrinsic properties and geologic and weathering history of rocks. Rock morphologies can be assessed quantitatively and compared with spectral data, to identify and classify rock types at the MPF landing site. They can also isolate actual rock spectra from spectral types that are surficial in origin, as compositions associated with mantling dust or chemical coatings would presumably not influence rock morphology during weathering events. We previously reported on an initial classification of rocks using the quantitative morphologic indices of size, roundness, sphericity and elongation. Here, we compare this database of rock characteristics with associated rock surface spectra to improve our ability to discriminate between spectra associated with rock types and those from other sources.

  12. What Solutions Caused Noachian Weathering on Mars?

    NASA Astrophysics Data System (ADS)

    Zolotov, M. Y.

    2015-12-01

    The stratified sequence of Al-rich and Fe/Mg phyllosilicates in Noachian formations indicates widespread chemical weathering of mafic materials [1]. The composition of alteration solutions could be inferred from the mineralogy of weathering profiles and models for water-rock interaction. We have developed numerical models for basalt weathering by acidic solutions with different concentrations of weak (H2CO3) and strong (H2SO4, HCl) acids equilibrated with low- and high-pressure CO2 atmospheres. The results show that the observed clay stratigraphies could be produced by neutral to strongly acidic solutions. Weathering by solutions equilibrated with dense CO2 atmospheres produces abundant carbonates at depth, which are not observed in clay stratigraphies. The development of weathering profiles by S-, Cl-free solutions equilibrated with 6 mbar CO2 requires large volumes of water. These volumes are inconsistent with density and orientation of Noachian valley networks and climate models [3-5]. Weathering by sulfate-free fluids does not produce abundant Ca sulfates reported in the Mawrth Valley region [2]. Weathering by low-pH H2SO4-bearing solutions does not require elevated water/rock ratios, a warm climate, or a dense CO2 atmosphere. It leads to formation of Ca sulfates in middle parts of weathering profiles together with neutralized Mg-rich sulfate solutions at depth. The weathering could have occurred through transient volcanism- and impact-generated supply of strong acids, and volcanism-, impact-, obliquity-related warming and partial ice melting, consistent with climate models [3-5]. Refs: [1] Carter, J. et al. (2015), Icarus 248, 373-382. [2] Wray, J. J. et al. (2010), Icarus 209, 416-421. [3] Wordsworth, R. et al. (2013), Icarus 222, 1-19. [4] Mischna, M. A. et al. (2013), J. Geophys. Res. Planets 118, 518-576. [5] Halevy, I., Head, J.W. (2014), Nature Geosci. 7, 865-868.

  13. Fun with Weather

    ERIC Educational Resources Information Center

    Yildirim, Rana

    2007-01-01

    This three-part weather-themed lesson for young learners connects weather, clothing, and feelings vocabulary. The target structures covered are: asking about the weather; comparing weather; using the modal auxiliary, should; and the question word, when. The lessons utilize all four skills and include such activities as going outside, singing,…

  14. Weather in Your Life.

    ERIC Educational Resources Information Center

    Kannegieter, Sandy; Wirkler, Linda

    Facts and activities related to weather and meteorology are presented in this unit. Separate sections cover the following topics: (1) the water cycle; (2) clouds; (3) the Beaufort Scale for rating the speed and force of wind; (4) the barometer; (5) weather prediction; (6) fall weather in Iowa (sleet, frost, and fog); (7) winter weather in Iowa…

  15. Teaching Weather Concepts.

    ERIC Educational Resources Information Center

    Sebastian, Glenn R.

    Ten exercises based on the weather map provided in the national newspaper "U.S.A. Today" are used to teach intermediate grade students about weather. An overview describes the history of "U.S.A. Today," the format of the newspaper's weather map, and the map's suitability for teaching weather concepts. Specific exercises, which are briefly…

  16. 'Earhart' Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a rock informally named 'Earhart' on the lower slopes of 'Endurance Crater.' The rock was named after the pilot Amelia Earhart. Like 'Escher' and other rocks dotting the bottom of Endurance, scientists believe fractures in Earhart could have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the rock's formation dried up. A third possibility is that much later, after the rock was formed, and after the crater was created, the rock became wet once again, then dried up and developed cracks. Rover team members do not have plans to investigate Earhart in detail because it is located across potentially hazardous sandy terrain. This image was taken on sol 219 (Sept. 4) by the rover's panoramic camera, using its 750-, 530- and 430-nanometer filters.

  17. The role of basalt weathering on climate: the Siberian traps

    NASA Astrophysics Data System (ADS)

    Grard, A.; François, L.; Dessert, C.; Dupré, B.; Goddéris, Y.

    2003-04-01

    The Siberian traps represent one of the most important flood basalt provinces on Earth. Their onset coincides with a profound faunal mass extinction at the Permo-Trias boundary (250 my ago). The volcanic eruption has also environmental and climatic effects through aerosols and gases injection into the atmosphere. Chemical weathering processes play a major role in biogeochemical cycles and climate evolution. In particular, the weathering of silicate rocks represents an important sink of atmospheric CO_2. At the million-year timescale, the volcanic release of CO_2 into the atmosphere-ocean system is balanced by its consumption during silicate weathering followed by carbonate deposition on the seafloor. Recent data have shown that chemical weathering of basalt is five to ten times more efficient than weathering of acidic silicate rocks such as granite or gneiss (Dessert et al., EPSL, 188 : 459-474, 2001). Thus the weathering of basaltic rocks consumes more atmospheric CO_2 than other silicate rocks. In the case of subaerial basaltic volcanism, an eruption not only releases CO_2 to the atmosphere, but also produces basaltic rocks which weather rapidly, enhancing CO_2 consumption rates. Currently, the Siberian basaltic traps are located in a cold and dry region. The weathering rates of this province are low, and the climatic impact is thus currently low. But in the past, the latitudinal temperature gradient was smaller. During the Permian, the climate was significantly warmer than today. Thus the chemical weathering of the Siberian traps was enhanced at that time, and this process led to a long-term impact on the Triassic climate and on the carbon cycle. The used model calculates the traps impact on the long-term carbon cycle and climate evolution. This model has been refined and adapted to high latitudes environments. We quantify the cooling caused by traps weathering.

  18. Science Rocks!

    ERIC Educational Resources Information Center

    Prestwich, Dorothy; Sumrall, Joseph; Chessin, Debby A.

    2010-01-01

    It all began one Monday morning. Raymond could not wait to come to large group. In his hand, he held a chunk of white granite he had found. "Look at my beautiful rock!" he cried. The rock was passed around and examined by each student. "I wonder how rocks are made?" wondered one student. "Where do they come from?" asked another. At this moment, a…

  19. Landslides as weathering reactors; links between physical erosion and weathering in rapidly eroding mountain belts

    NASA Astrophysics Data System (ADS)

    Emberson, R.; Hovius, N.; Galy, A.

    2014-12-01

    The link between physical erosion and chemical weathering is generally modelled with a surface-blanketing weathering zone, where the supply of fresh minerals is tied to the average rate of denudation. In very fast eroding environments, however, sediment production is dominated by landsliding, which acts in a stochastic fashion across the landscape, contrasting strongly with more uniform denudation models. If physical erosion is a driver of weathering at the highest erosion rates, then an alternative weathering model is required. Here we show that landslides can be effective 'weathering reactors'. Previous work modelling the effect of landslides on chemical weathering (Gabet 2007) considered the fresh bedrock surfaces exposed in landslide scars. However, fracturing during the landslide motion generates fresh surfaces, the total surface area of which exceeds that of the exposed scar by many orders of magnitude. Moreover, landslides introduce concavity into hillslopes, which acts to catch precipitation. This is funnelled into a deposit of highly fragmented rock mass with large reactive surface area and limited hydraulic conductivity (Lo et al. 2007). This allows percolating water reaction time for chemical weathering; any admixture of macerated organic debris could yield organic acid to further accelerate weathering. In the South island of New Zealand, seepage from recent landslide deposits has systematically high solute concentrations, far outstripping concentration in runoff from locations where soils are present. River total dissolved load in the western Southern Alps is highly correlated with the rate of recent (<35yrs) landsliding, suggesting that landslides are the dominant locus of weathering in this rapidly eroding landscape. A tight link between landsliding and weathering implies that localized weathering migrates through the landscape with physical erosion; this contrasts with persistent and ubiquitous weathering associated with soil production. Solute

  20. Rock flows

    NASA Technical Reports Server (NTRS)

    Matveyev, S. N.

    1986-01-01

    Rock flows are defined as forms of spontaneous mass movements, commonly found in mountainous countries, which have been studied very little. The article considers formations known as rock rivers, rock flows, boulder flows, boulder stria, gravel flows, rock seas, and rubble seas. It describes their genesis as seen from their morphological characteristics and presents a classification of these forms. This classification is based on the difference in the genesis of the rubbly matter and characterizes these forms of mass movement according to their source, drainage, and deposit areas.

  1. Constraints on the Global-scale Chemical Weathering State of Mars From TES Results Based on Spectral Analysis of Chemically Weathered Basalts

    NASA Astrophysics Data System (ADS)

    Michalski, J. R.; Kraft, M. D.; Sharp, T. G.; Christensen, P. R.

    2005-12-01

    On Earth, subaerially exposed basaltic rocks (from arid-to-tropical regions) develop weathering rinds and rock coatings that affect spectroscopic measurements of their natural surfaces. Similarly, basaltic rocks and basaltic soil particles on Mars may have rinds and coatings that are spectroscopically observable. Thermal emission spectroscopy, because it provides information about the composition and structure of silicate and non-silicate minerals and mineraloids, provides a useful perspective on the mineralogy of weathered surfaces; reconciliation of the emission spectral features of weathered surfaces with observations from other datasets is critical to interpretations of thermal emission spectral features of Mars. In this study, we investigate the thermal emission (6-25 μm) and visible/near-infrared (VNIR) (0.4-2.5 μm) spectroscopic features of fresh and weathered surfaces of rock samples from the Columbia River Basalt Group (CRBG). VNIR spectra of weathered rock surfaces are brighter and redder than fresh rock surfaces, but contain no evidence for neoformation of clay minerals within subaerially exposed, weathered surfaces. In contrast, thermal emission spectroscopy suggests an enrichment of clay minerals in weathered surfaces. Also, thermal emission spectroscopy indicates the presence of glass-like materials in many weathered surfaces, which likely correspond to amorphous weathering products present within fractures, as coatings on minerals, or as coatings on the rocks themselves. These results have important implications for interpretation of TES and THEMIS data of Mars, including: 1) glasses and clays detected on Mars from thermal infrared spectra may correspond to poorly crystalline weathering products within chemically weathered rock surfaces, 2) chemically weathered surfaces of basalts may appear oxidized but clay-poor to VNIR datasets, and 3) the differential chemical breakdown of primary phases can affect interpretations of the remaining primary rock

  2. 'Tetl' Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image, taken by the panoramic camera on NASA's Mars Exploration Rover Spirit during the rover's trek through the 'Columbia Hills' at 'Gusev Crater,' shows the horizontally layered rock dubbed 'Tetl.' Scientists hope to investigate this rock in more detail, aiming to determine whether the rock's layering is volcanic or sedimentary in origin. If for some reason this particular rock is not favorably positioned for grinding and examination by the toolbox of instruments on the rover's robotic arm, Spirit will be within short reach of another similar rock, dubbed 'Coba.' Spirit took this image on its 264th martian day, or sol (Sept. 29, 2004). This is a false-color composite image generated from the panoramic camera's 750-, 530-, and 430-nanometer filters.

  3. Global chemical weathering and associated P-release

    NASA Astrophysics Data System (ADS)

    Hartmann, Jens; Moosdorf, Nils; Lauerwald, Ronny; Hinderer, Matthias; West, A. Joshua

    2014-05-01

    Chemical weathering releases phosphorus to soils and ecosystems. To improve understanding of the spatial distribution of the global P-release characteristics, a model framework for estimating global chemical weathering rates was coupled with geochemical information. Results suggest that the global soil shielding reduces chemical weathering fluxes by about 44%, compared to an Earth surface with no deeply weathered soils but relatively young rock surfaces (e.g. as in volcanic arc and other tectonically active areas). About 70% of the weathering fluxes globally derive from 10% of the land area, with Southeast Asia being a primary "hot spot" of chemical weathering and for P-release. In contrast, only 50% of runoff is attributed to 10% of the land area; thus the global chemical weathering rating curve is to some extent disconnected from the global runoff curve due to the spatially heterogeneous climate as well as differences in rock and soil properties. In addition to total chemical weathering fluxes, the release of P, a nutrient that controls biological productivity at large spatial scales, is affected by the spatial correlation between runoff, lithology, temperature and soil properties. The areal abundance of deeply weathered soils in Earth's past may have influenced weathering fluxes and P-fuelled biological productivity significantly, specifically in the case of larger climate shifts when high runoff fields shift to areas with thinner soils or areas with more weatherable rocks and relatively increased P-content. This observation may be particularly important for spatially resolved Earth system models targeting geological time scales. The full research text can be found in: Hartmann, J., N. Moosdorf, R. Lauerwald, M. Hinderer, A.J. West (2014) Global chemical weathering and associated P-release - the role of lithology, temperature and soil properties. Chemical Geology 363, 145-163. doi: 10.1016/j.chemgeo.2013.10.025 (open access)

  4. Pilot weather advisor

    NASA Technical Reports Server (NTRS)

    Kilgore, W. A.; Seth, S.; Crabill, N. L.; Shipley, S. T.; Graffman, I.; Oneill, J.

    1992-01-01

    The results of the work performed by ViGYAN, Inc., to demonstrate the Pilot Weather Advisor cockpit weather data system using a broadcast satellite communication system are presented. The Pilot Weather Advisor demonstrated that the technical problems involved with transmitting significant amount of weather data to an aircraft in-flight or on-the-ground via satellite are solvable with today's technology. The Pilot Weather Advisor appears to be a viable solution for providing accurate and timely weather information for general aviation aircraft.

  5. Weather Information System

    NASA Technical Reports Server (NTRS)

    1995-01-01

    WxLink is an aviation weather system based on advanced airborne sensors, precise positioning available from the satellite-based Global Positioning System, cockpit graphics and a low-cost datalink. It is a two-way system that uplinks weather information to the aircraft and downlinks automatic pilot reports of weather conditions aloft. Manufactured by ARNAV Systems, Inc., the original technology came from Langley Research Center's cockpit weather information system, CWIN (Cockpit Weather INformation). The system creates radar maps of storms, lightning and reports of surface observations, offering improved safety, better weather monitoring and substantial fuel savings.

  6. Dynamic tensile strength of lunar rock types

    NASA Technical Reports Server (NTRS)

    Cohn, S. N.; Ahrens, T. J.

    1981-01-01

    The dynamic tensile strength of four rocks are determined. A flat plate impact experiment is employed to generate approximately one-microsecond-duration tensile stress pulses in rock samples by superposing rarefaction waves to induce fracture. It is noted that the effect of chemical weathering and other factors has not been explicitly studied. The given tensile strengths are based on a series of experiments on each rock where determination of incipient spallation is made by terminal microscopic examination. The data are generally consistent with previous determinations, at least one of which was for a significantly chemically altered but physically coherent rock.

  7. Art Rocks with Rock Art!

    ERIC Educational Resources Information Center

    Bickett, Marianne

    2011-01-01

    This article discusses rock art which was the very first "art." Rock art, such as the images created on the stone surfaces of the caves of Lascaux and Altimira, is the true origin of the canvas, paintbrush, and painting media. For there, within caverns deep in the earth, the first artists mixed animal fat, urine, and saliva with powdered minerals…

  8. Terby's Rocks

    NASA Technical Reports Server (NTRS)

    2006-01-01

    27 January 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the light-toned, layered, sedimentary rock outcrops in northern Terby Crater. Terby is located along the north edge of Hellas Planitia. The sedimentary rocks might have been deposited in a greater, Hellas-filling sea -- or not. Today, the rocks are partly covered by dark-toned sediment and debris.

    Location near: 27.2oS, 285.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  9. Winter Weather: Indoor Safety

    MedlinePlus

    ... page: About CDC.gov . Natural Disasters and Severe Weather Earthquakes Being Prepared Emergency Supplies Home Hazards Indoor ... Heat Prevention Guide (Part 3 of 3) Hot Weather Tips Heat Stress in Older Adults FAQs Extreme ...

  10. Winter Weather Emergencies

    MedlinePlus

    Severe winter weather can lead to health and safety challenges. You may have to cope with Cold related health problems, including ... there are no guarantees of safety during winter weather emergencies, you can take actions to protect yourself. ...

  11. On nutrients and trace metals: Effects from Enhanced Weathering

    NASA Astrophysics Data System (ADS)

    Amann, T.; Hartmann, J.

    2015-12-01

    The application of rock flour on suitable land ("Enhanced Weathering") is one proposed strategy to reduce the increase of atmospheric CO2 concentrations. At the same time it is an old and established method to add fertiliser and influence soil properties. Investigations of this method focused on the impact on the carbonate system, as well as on engineering aspects of a large-scale application, but potential side effects were never discussed quantitatively. We analysed about 120,000 geochemically characterised volcanic rock samples from the literature. Applying basic statistics, theoretical release rates of nutrients and potential contaminants by Enhanced Weathering were evaluated for typical rock types. Applied rock material can contain significant amounts of essential or beneficial nutrients (potassium, phosphorus, micronutrients). Their release can partly cover the demand of major crops like wheat, rice or corn, thereby increasing crop yield on degraded soils. However, the concentrations of considered elements are variable within a specific rock type, depending on the geological setting. High heavy metal concentrations are found in (ultra-) basic rocks, the class with the highest CO2 drawdown potential. More acidic rocks contain less or no critical amounts, but sequester less CO2. Findings show that the rock selection determines the capability to supply significant amounts of nutrients, which could partly substitute industrial mineral fertiliser usage. At the same time, the release of harmful trace element has to be considered. Through careful selection of regionally available rocks, benefits could be maximised and drawbacks reduced. The deployment of Enhanced Weathering to sequester CO2 and to ameliorate soils necessitates an ecosystem management, considering the release and fate of weathered elements in plants, soils and water. Cropland with degraded soils would benefit while having a net negative CO2 effect, while other carbon dioxide removal strategies, like

  12. Carbonatisation of Weathered Peridotites in Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Hövelmann, J.; Austrheim, H.; Beinlich, A.; Munz, I. A.

    2010-12-01

    Enhanced in-situ carbonatisation of ultramafic rocks has been proposed as a strategy for a permanent and safe storage of CO2 in order to reduce anthropogenic greenhouse gas emissions (e.g., Kelemen and Matter 2008). This idea emerged from studies of natural examples demonstrating that ultramafic rocks react extensively with CO2 to form ophicarbonates. However, despite their Mg-rich nature, ultramafic rocks are often associated with calcite (CaCO3) rather than magnesite (MgCO3) and dolomite (CaMg(CO3)2). Whether these so-called ophicalcites represent sedimentary or tectonic breccias or are produced during hydrothermal alteration of ultramafic rocks, has been discussed for many years (e.g., Folk and McBride 1976). The view that reactions between hydrothermal fluids and ultramafic rocks can result in the formation of ophicalcite was recently supported by Beinlich et al. (2010), who documented Ca- and CO2-metasomatism and extreme Mg depletion in serpentinised and weathered peridotite clasts from the conglomerates of the Solund basin (SW Norway). This study also suggests that weathering is an important factor for the carbonatisation of ultramafic rocks. We have performed hydrothermal experiments on weathered peridotites in order to better constrain the mechanisms and conditions that trigger Mg-loss from ultramafic rocks and subsequent calcite precipitation. Un-crushed, partly serpentinised and weathered peridotite samples were allowed to react in a Ca-bearing saline solution under CO2 pressure (PCO2: 130-160 bar) at 200°C. We were able to illustrate the textural and chemical evolution during the reaction through a detailed comparison of the solid and fluid samples before and after the experiments. The initial samples showed a typical mesh texture with veins of serpentine surrounding meshes filled either with fresh or weathered olivine. The experimentally treated samples reveal a strongly reacted rim, predominantly composed of calcite, but still showing ghosts of the

  13. Convective Weather Avoidance with Uncertain Weather Forecasts

    NASA Technical Reports Server (NTRS)

    Karahan, Sinan; Windhorst, Robert D.

    2009-01-01

    Convective weather events have a disruptive impact on air traffic both in terminal area and in en-route airspaces. In order to make sure that the national air transportation system is safe and efficient, it is essential to respond to convective weather events effectively. Traffic flow control initiatives in response to convective weather include ground delay, airborne delay, miles-in-trail restrictions as well as tactical and strategic rerouting. The rerouting initiatives can potentially increase traffic density and complexity in regions neighboring the convective weather activity. There is a need to perform rerouting in an intelligent and efficient way such that the disruptive effects of rerouting are minimized. An important area of research is to study the interaction of in-flight rerouting with traffic congestion or complexity and developing methods that quantitatively measure this interaction. Furthermore, it is necessary to find rerouting solutions that account for uncertainties in weather forecasts. These are important steps toward managing complexity during rerouting operations, and the paper is motivated by these research questions. An automated system is developed for rerouting air traffic in order to avoid convective weather regions during the 20- minute - 2-hour time horizon. Such a system is envisioned to work in concert with separation assurance (0 - 20-minute time horizon), and longer term air traffic management (2-hours and beyond) to provide a more comprehensive solution to complexity and safety management. In this study, weather is dynamic and uncertain; it is represented as regions of airspace that pilots are likely to avoid. Algorithms are implemented in an air traffic simulation environment to support the research study. The algorithms used are deterministic but periodically revise reroutes to account for weather forecast updates. In contrast to previous studies, in this study convective weather is represented as regions of airspace that pilots

  14. Weather Fundamentals: Meteorology. [Videotape].

    ERIC Educational Resources Information Center

    1998

    The videos in this educational series, for grades 4-7, help students understand the science behind weather phenomena through dramatic live-action footage, vivid animated graphics, detailed weather maps, and hands-on experiments. This episode (23 minutes) looks at how meteorologists gather and interpret current weather data collected from sources…

  15. American Weather Stories.

    ERIC Educational Resources Information Center

    Hughes, Patrick

    Weather has shaped United States' culture, national character and folklore; at times it has changed the course of history. The seven accounts compiled in this publication highlight some of the nation's weather experiences from the hurricanes that threatened Christopher Columbus to the peculiar run of bad weather that has plagued American…

  16. Severe Weather Perceptions.

    ERIC Educational Resources Information Center

    Abrams, Karol

    Severe weather is an element of nature that cannot be controlled. Therefore, it is important that the general public be aware of severe weather and know how to react quickly and appropriately in a weather emergency. This study, done in the community surrounding the Southern Illinois University at Carbondale, was conducted to compile and analyze…

  17. Aviation weather services

    NASA Technical Reports Server (NTRS)

    Sprinkle, C. H.

    1983-01-01

    The primary responsibilities of the National Weather Service (NWS) are to: provide warnings of severe weather and flooding for the protection of life and property; provide public forecasts for land and adjacent ocean areas for planning and operation; and provide weather support for: production of food and fiber; management of water resources; production, distribution and use of energy; and efficient and safe air operations.

  18. Rock Garden

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This false color composite image of the Rock Garden shows the rocks 'Shark' and 'Half Dome' at upper left and middle, respectively. Between these two large rocks is a smaller rock (about 0.20 m wide, 0.10 m high, and 6.33 m from the Lander) that was observed close-up with the Sojourner rover (see PIA00989).

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  19. Hydrochemistry, weathering and weathering rates on Madeira island

    NASA Astrophysics Data System (ADS)

    Van der Weijden, Cornelis H.; Pacheco, Fernando A. L.

    2003-12-01

    Madeira island consists of Miocene to Pleistocene lavas and pyroclasts. Major rock types are alkali-basalts, basanites and hawaiites; principal soil types are leptosols, andosols and cambisols. Our main objective was to link the chemistry of ground waters to weathering reactions and rates. We collected 40 shallow groundwater samples, remote from human activities. With a few exceptions, the ranges of electrical conductivities were 29-176 μS/cm and of pH 5.8-8.5. The calculated PCO 2 was generally higher than the atmospheric value. The contribution of sea salt to the water chemistry was 30±9%. Corrected for sea salt, the cation concentrations (in meq/l) decrease in the order Ca 2+≈Mg 2+>Na +>>>K +. The concentrations of SO 42- and NO 3- are very low. We calculated that the total annual chemical denudation rate in the studied area amounts to 37±12 g/m 2, consuming 0.86±0.38 mol CO 2/m 2. To achieve our main objective, a set of mole balance equations— ( AX= B)—was used, where A is a composite matrix of coefficients, including ratios between stoichiometric coefficients as determined by the weathering reactions and coefficients accounting for unconstrained contributions, B is the vector with a water composition, and X is the set of mole fractions of dissolved primary minerals plus the residual concentrations of the unconstrained contributions. Olivine (Ol), pyroxene (Py) and plagioclase (Pl) were considered to be the major primary minerals, and smectite, vermiculite, halloysite, allophane, gibbsite and hematite the secondary minerals in the weathering reactions. Using iterative procedures, whereby mixtures of secondary products as well as the composition of plagioclase are allowed to change, we selected one best-fit set of weathering reactions for each spring by checking all possible solutions of the mole balances against predefined boundary conditions. At odds with Goldich (1938) sequence, our model results indicate—for most best-fit sets—a weathering rate

  20. Atmospheric CO2 Removal by Enhancing Weathering

    NASA Astrophysics Data System (ADS)

    Koster van Groos, A. F.; Schuiling, R. D.

    2014-12-01

    The increase of the CO2 content in the atmosphere by the release of anthropogenic CO2 may be addressed by the enhancement of weathering at the surface of the earth. The average emission of mantle-derived CO2 through volcanism is ~0.3 Gt/year (109 ton/year). Considering the ~3.000 Gt of CO2 present in the atmosphere, the residence time of CO2 in the earth's atmosphere is ~10,000 years. Because the vast proportion of carbon in biomass is recycled through the atmosphere, CO2 is continuously removed by a series of weathering reactions of silicate minerals and stored in calcium and magnesium carbonates. The addition of anthropogenic CO2 from fossil fuel and cement production, which currently exceeds 35 Gt/year and dwarfs the natural production 100-fold, cannot be compensated by current rates of weathering, and atmospheric CO2 levels are rising rapidly. To address this increase in CO2 levels, weathering rates would have to be accelerated on a commensurate scale. Olivine ((Mg,Fe)2SiO4) is the most reactive silicate mineral in the weathering process. This mineral is the major constituent in relatively common ultramafic rocks such as dunites (olivine content > 90%). To consume the current total annual anthropogenic release of CO2, using a simplified weathering reaction (Mg2SiO4 + 4CO2 + 4H2O --> 2 Mg2+ + 4HCO3- + H4SiO4) would require ~30 Gt/year or ~8-9 km3/year of dunite. This is a large volume; it is about double the total amount of ore and gravel currently mined (~ 17 Gt/year). To mine and crush these rocks to <100 μm costs ~ 8/ton. The transport and distribution over the earth's surface involves additional costs, that may reach 2-5/ton. Thus, the cost of remediation for the release of anthropogenic CO2 is 300-400 billion/year. This compares to a 2014 global GDP of ~80 trillion. Because weathering reactions require the presence of water and proceed more rapidly at higher temperatures, the preferred environments to enhance weathering are the wet tropics. From a socio

  1. Experimental study on weathering of seafloor volcanic glass by bacteria (Pseudomonas fluorescens) - Implications for the contribution of bacteria to the wate-rock reaction at the Mid-Oceanic Ridge setting

    NASA Astrophysics Data System (ADS)

    Chen, Shun; Wu, Zijun; Peng, Xiaotong

    2014-08-01

    The biologically mediated weathering of the ocean crust has received increasing attention in recent decades, but the rates and the possible mechanism of elemental release during microbe-basalt interactions occurring below the seafloor have not been studied in detail. In this study, we established an experimental weathering study of seafloor natural basaltic glass comparing the effect of microbial activity (Pseudomonas fluorescens) in P-rich and P-poor media with parallel controls containing either nonviable cells or organic acid. The changes in the chemical parameters, including pH, bacterial densities, and ion concentrations (Ca, Mg, Si, Mn, Al, Fe, and P) in the solution, were examined during the different batch experiments. The results showed that the pH decreased from 7.0 to 3.5 and the bacterial density increased from 105 to 108 cells/ml during the first 120 h, and the cell numbers remained constant at 108 cells/ml and the pH increased from 3.5 to 6 between 120 h and 864 h in the P-bearing reactors containing bacteria. In contrast, during all the experimental time, the pH remained close to neutral condition in the abiotic control systems and the dissolution rates increased markedly with a decrease in pH and became minimal at near-neutral pH in P-bearing reactors containing bacteria, where Ca, Si, and Mg release rates were 2- to 4-fold higher than those obtained in chemical systems and biotic P-limited systems. Furthermore, the surfaces of the natural volcanic glass from the biotic systems were colonized by bacteria. Simultaneously, the etch pits were observed by Scanning Electron Microscope, which further indicate that the bacteria may promote the mineral dissolution for energy gain. Some elements (e.g., Fe, Mn, and Al) releasing from natural volcanic glass are likely an important source of the elemental budget in the ocean, and thus the element release and its possible mechanism conducted in this experimental study have potential implications on the

  2. Weatherization and Intergovernmental Program - Weatherization Assistance Program

    SciTech Connect

    2010-06-01

    The U.S. Department of Energy’s (DOE) Weatherization Assistance Program reduces energy costs for low-income households by increasing the energy efficiency of their homes, while ensuring their health and safety.

  3. Beyond the Weather Chart: Weathering New Experiences.

    ERIC Educational Resources Information Center

    Huffman, Amy Bruno

    1996-01-01

    Describes an early childhood educator's approach to teaching children about rain, rainbows, clouds, precipitation, the sun, air, and wind. Recommends ways to organize study topics and describes experiments that can help children better understand the different elements of weather. (MOK)

  4. Questa Baseline and Pre-mining Ground-Water Quality Investigation, 7. A Pictorial Record of Chemical Weathering, Erosional Processes, and Potential Debris-flow Hazards in Scar Areas Developed on Hydrothermally Altered Rocks

    USGS Publications Warehouse

    Plumlee, Geoffrey S.; Ludington, Steve; Vincent, Kirk R.; Verplanck, Philip L.; Caine, Jonathan S.; Livo, K. Eric

    2009-01-01

    Erosional scar areas developed along the lower Red River basin, New Mexico, reveal a complex natural history of mineralizing processes, rapid chemical weathering, and intense physical erosion during periodic outbursts of destructive, storm-induced runoff events. The scar areas are prominent erosional features with craggy headwalls and steep, denuded slopes. The largest scar areas, including, from east to west, Hottentot Creek, Straight Creek, Hansen Creek, Lower Hansen Creek, Sulfur Gulch, and Goat Hill Gulch, head along high east-west trending ridges that form the northern and southern boundaries of the lower Red River basin. Smaller, topographically lower scar areas are developed on ridge noses in the inner Red River valley. Several of the natural scar areas have been modified substantially as a result of large-scale open-pit and underground mining at the Questa Mine; for example, much of the Sulfur Gulch scar was removed by open pit mining, and several scars are now partially or completely covered by mine waste dumps.

  5. [Suicide and weather].

    PubMed

    Breuer, H W; Fischbach-Breuer, B R; Breuer, J; Goeckenjan, G; Curtius, J M

    1984-11-01

    In 151 patients, admitted to an intensive care unit after attempted suicide, the possible influence of weather at the time of the attempt was analysed retrospectively. The "biosynoptic daily analysis" of the German Weather Service provided the weather data. There was a 5% and 1%, respectively, significant level for the positive correlation between the time of the attempted suicide and the weather parameters "stable upslide, labile upslide, fog and thunderstorm" and the summarized parameters "warm air, upslide and weather drier than on the two preceding days". Significantly fewer attempts than expected occurred when the weather description was "low pressure and trough situation, labile ground layer--upslide above" and the summarized parameters "subsidence or downslide motion". Besides the individual factors such as the reaction to conflicts and the spectrum of reactions, exogenous factors like weather must be considered as important for the time of suicidal attempt. PMID:6499669

  6. 11. COULTERVILLE ROAD AT ROCK SLIDE AREA WITH HWY 140 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. COULTERVILLE ROAD AT ROCK SLIDE AREA WITH HWY 140 AT REAR. LOOKING NNE. GIS: N-37 43 04.7 / W-119 43 00.3 - Coulterville Road, Between Foresta & All-Weather Highway, Yosemite Village, Mariposa County, CA

  7. Pyroclastic Rocks

    NASA Astrophysics Data System (ADS)

    Mahood, Gail A.

    Most of the advances in volcanology during the past 20 years have concerned the recognition, interpretation, and mode of emplacement of pyroclastic rocks. The literature on pyroclastic rocks is widely scattered, in part because the field draws from sedimentology, igneous petrology, physics, and fluid mechanics, and there have been few review papers on the topic. Fisher and Schmincke have done the discipline of volcanology and all field-oriented geologists a great service in assembling material from a wide range of sources in this comprehensive treatment of pyroclastic rocks. With its introduction to the petrology of magmas involved in explosive eruptions in chapter 2 and a complete treatment of magma rheology and the behavior of dissolved and exsolving magmatic volatiles in chapter 3, they lay sufficient groundwork that anyone with a rudimentary knowledge of geology can understand the book.

  8. [Weathering seasonal variations in karst valley in southwest China].

    PubMed

    Xiao, Qiong; Shen, Li-Cheng; Yang, Lei; Wu, Kun-Yu; Chen, Zhan-Tu

    2012-04-01

    Jialing River is a 1st grade tributary of upstream Yangzi River. In two years, Samples were collected monthly in Wentang Gorge section of Jialing River and analyzed multi-parameters including hydrochemistry and isotopes. Thus, a general result was concluded that the hydrochemical characteristic of Jialing River in Wentang gorge is controlled by weathering of stratum and the hydrochemical type is HCO3(-) -Ca. Most irons were influenced by dilution, which had higher concentrations in dry season than that in rainy season, but nitrate. Nitrate, which was controlled by human activities, has higher concentrations in rainy season. However, some other analyst revealed weathering impacts. The contrast ratio of (Ca(2+) + Mg2+) and HCO3- were between 0.5-1, the same as (Ca(2+) + Mg2+) and (HCO3(-) + SO4(2-)), Which implied that the weathering impacts in this basin was mainly carbonated and sulfate weathering of carbonated, and sulphate rocks weathering was not so significant. The values of delta13C(HCO3- in Jialing River were -8.74 per thousand(-) - 7.36 per thousand, and delta34S(SO)(4)2 - was 14.43 per thousand in dry season and 12.21 per thousand in rainy season. The data of isotopes inferred that, in rainy season sulfate weathering of carbonated and sulphate rocks weathering both had more impacts and sulphate rocks weathering played a more important role than sulfate weathering of carbonated, but, in dry season, carbonated weathering of carbonated was more meaningful. PMID:22720555

  9. Seafloor weathering buffering climate: numerical experiments

    NASA Astrophysics Data System (ADS)

    Farahat, N. X.; Archer, D. E.; Abbot, D. S.

    2013-12-01

    Continental silicate weathering is widely held to consume atmospheric CO2 at a rate controlled in part by temperature, resulting in a climate-weathering feedback [Walker et al., 1981]. It has been suggested that weathering of oceanic crust of warm mid-ocean ridge flanks also has a CO2 uptake rate that is controlled by climate [Sleep and Zahnle, 2001; Brady and Gislason, 1997]. Although this effect might not be significant on present-day Earth [Caldeira, 1995], seafloor weathering may be more pronounced during snowball states [Le Hir et al., 2008], during the Archean when seafloor spreading rates were faster [Sleep and Zahnle, 2001], and on waterworld planets [Abbot et al., 2012]. Previous studies of seafloor weathering have made significant contributions using qualitative, generally one-box, models, and the logical next step is to extend this work using a spatially resolved model. For example, experiments demonstrate that seafloor weathering reactions are temperature dependent, but it is not clear whether the deep ocean temperature affects the temperature at which the reactions occur, or if instead this temperature is set only by geothermal processes. Our goal is to develop a 2-D numerical model that can simulate hydrothermal circulation and resulting alteration of oceanic basalts, and can therefore address such questions. A model of diffusive and convective heat transfer in fluid-saturated porous media simulates hydrothermal circulation through porous oceanic basalt. Unsteady natural convection is solved for using a Darcy model of porous media flow that has been extensively benchmarked. Background hydrothermal circulation is coupled to mineral reaction kinetics of basaltic alteration and hydrothermal mineral precipitation. In order to quantify seafloor weathering as a climate-weathering feedback process, this model focuses on hydrothermal reactions that influence carbon uptake as well as ocean alkalinity: silicate rock dissolution, calcium and magnesium leaching

  10. Geochemical investigation of weathering processes in a forested headwater catchment: Mass-balance weathering fluxes

    USGS Publications Warehouse

    Jones, B.F.; Herman, J.S.

    2008-01-01

    Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basic hydrology. O'Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile. ?? 2008 The Mineralogical Society.

  11. Weathering profiles in granites, Sierra Norte (Córdoba, Argentina)

    NASA Astrophysics Data System (ADS)

    Kirschbaum, Alicia; Martínez, Estela; Pettinari, Gisela; Herrero, Silvana

    2005-09-01

    Two weathering profiles evolved on peneplain-related granites in Sierra Norte, Córdoba province, were examined. Several weathering levels, of no more than 2 m thickness, were studied in these profiles. They had developed from similar parent rock, which had been exposed to hydrothermal processes of varying intensity. Fracturing is the most notable feature produced by weathering; iron oxides and silica subsequently filled these fractures, conferring a breccia-like character to the rock. The clay minerals are predominantly illitic, reflecting the mineral composition of the protolith. Smaller amounts of interstratified I/S RO type are also present, as well as scarce caolinite+chlorite that originated from the weathering of feldspar and biotite, respectively. The geochemical parameters define the weathering as incipient, in contrast to the geomorphological characteristics of Sierra Norte, which point to a long weathering history. This apparent incompatibility could be due to the probable erosion of the more weathered levels of the ancient peneplains, of which only a few relicts remain. Similar processes have been described at different sites in the Sierras Pampeanas. Reconstruction and dating of the paleosurfaces will make it possible to set time boundaries on the weathering processes studied and adjust the paleographic and paleoclimatic interpretations of this great South American region.

  12. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains what high and low pressure weather systems are, and how these affect weather patterns. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  13. RBSP Space Weather data

    NASA Astrophysics Data System (ADS)

    Weiss, M.; Fox, N. J.; Mauk, B. H.; Barnes, R. J.; Potter, M.; Romeo, G.; Smith, D.

    2012-12-01

    On August 23, 2012, NASA will launch two identical probes into the radiation belts to provide unprecedented insight into the physical processes and dynamics of near-Earth space. The RBSP mission in addition to the scientific data return, provides a 1Kbps real-time space weather broadcast data in support of real time space weather modeling, forecast and prediction efforts. Networks of ground stations have been identified to downlink the space weather data. The RBSP instrument suites have selected space weather data to be broadcast from their collected space data on board the spacecraft, a subset from measurements based on information normally available to the instrument. The data subset includes particle fluxes at a variety of energies, and magnetic and electric field data. This selected space weather data is broadcast at all times through the primary spacecraft science downlink antennas when an observatory is not in a primary mission-related ground contact. The collected data will resolve important scientific issues and help researchers develop and improve various models for the radiation belts that can be used by forecasters to predict space weather phenomena and alert astronauts and spacecraft operators to potential hazards. The near real-time data from RBSP will be available to monitor and analyze current environmental conditions, forecast natural environmental changes and support anomaly resolution. The space weather data will be available on the RBSP Science Gateway at http://athena.jhuapl.edu/ and will provide access to the space weather data received from the RBSP real-time space weather broadcast. The near real-time data will be calibrated and displayed on the web as soon as possible. The CCMC will ingest the RBSP space weather data into real-time models. The raw space weather data will be permanently archived at APL. This presentation will provide a first look at RBSP space weather data products.

  14. Weather and climate

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Recommendations for using space observations of weather and climate to aid in solving earth based problems are given. Special attention was given to: (1) extending useful forecasting capability of space systems, (2) reducing social, economic, and human losses caused by weather, (3) development of space system capability to manage and control air pollutant concentrations, and (4) establish mechanisms for the national examination of deliberate and inadvertent means for modifying weather and climate.

  15. Classic Rock

    ERIC Educational Resources Information Center

    Beem, Edgar Allen

    2004-01-01

    While "early college" programs designed for high-school-age students are beginning to proliferate nationwide, a small New England school has been successfully educating teens for nearly four decades. In this article, the author features Simon's Rock, a small liberal arts college located in the Great Barrington, Massachusetts, that has been…

  16. Pilot Weather Advisor System

    NASA Technical Reports Server (NTRS)

    Lindamood, Glenn; Martzaklis, Konstantinos Gus; Hoffler, Keith; Hill, Damon; Mehrotra, Sudhir C.; White, E. Richard; Fisher, Bruce D.; Crabill, Norman L.; Tucholski, Allen D.

    2006-01-01

    The Pilot Weather Advisor (PWA) system is an automated satellite radio-broadcasting system that provides nearly real-time weather data to pilots of aircraft in flight anywhere in the continental United States. The system was designed to enhance safety in two distinct ways: First, the automated receipt of information would relieve the pilot of the time-consuming and distracting task of obtaining weather information via voice communication with ground stations. Second, the presentation of the information would be centered around a map format, thereby making the spatial and temporal relationships in the surrounding weather situation much easier to understand

  17. Cockpit weather information needs

    NASA Technical Reports Server (NTRS)

    Scanlon, Charles H.

    1992-01-01

    The primary objective is to develop an advanced pilot weather interface for the flight deck and to measure its utilization and effectiveness in pilot reroute decision processes, weather situation awareness, and weather monitoring. Identical graphical weather displays for the dispatcher, air traffic control (ATC), and pilot crew should also enhance the dialogue capabilities for reroute decisions. By utilizing a broadcast data link for surface observations, forecasts, radar summaries, lightning strikes, and weather alerts, onboard weather computing facilities construct graphical displays, historical weather displays, color textual displays, and other tools to assist the pilot crew. Since the weather data is continually being received and stored by the airborne system, the pilot crew has instantaneous access to the latest information. This information is color coded to distinguish degrees of category for surface observations, ceiling and visibilities, and ground radar summaries. Automatic weather monitoring and pilot crew alerting is accomplished by the airborne computing facilities. When a new weather information is received, the displays are instantaneously changed to reflect the new information. Also, when a new surface or special observation for the intended destination is received, the pilot crew is informed so that information can be studied at the pilot's discretion. The pilot crew is also immediately alerted when a severe weather notice, AIRMET or SIGMET, is received. The cockpit weather display shares a multicolor eight inch cathode ray tube and overlaid touch panel with a pilot crew data link interface. Touch sensitive buttons and areas are used for pilot selection of graphical and data link displays. Time critical ATC messages are presented in a small window that overlays other displays so that immediate pilot alerting and action can be taken. Predeparture and reroute clearances are displayed on the graphical weather system so pilot review of weather along

  18. Weather assessment and forecasting

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Data management program activities centered around the analyses of selected far-term Office of Applications (OA) objectives, with the intent of determining if significant data-related problems would be encountered and if so what alternative solutions would be possible. Three far-term (1985 and beyond) OA objectives selected for analyses as having potential significant data problems were large-scale weather forecasting, local weather and severe storms forecasting, and global marine weather forecasting. An overview of general weather forecasting activities and their implications upon the ground based data system is provided. Selected topics were specifically oriented to the use of satellites.

  19. Weather it's Climate Change?

    NASA Astrophysics Data System (ADS)

    Bostrom, A.; Lashof, D.

    2004-12-01

    For almost two decades both national polls and in-depth studies of global warming perceptions have shown that people commonly conflate weather and global climate change. Not only are current weather events such as anecdotal heat waves, droughts or cold spells treated as evidence for or against global warming, but weather changes such as warmer weather and increased storm intensity and frequency are the consequences most likely to come to mind. Distinguishing weather from climate remains a challenge for many. This weather 'framing' of global warming may inhibit behavioral and policy change in several ways. Weather is understood as natural, on an immense scale that makes controlling it difficult to conceive. Further, these attributes contribute to perceptions that global warming, like weather, is uncontrollable. This talk presents an analysis of data from public opinion polls, focus groups, and cognitive studies regarding people's mental models of and 'frames' for global warming and climate change, and the role weather plays in these. This research suggests that priming people with a model of global warming as being caused by a "thickening blanket of carbon dioxide" that "traps heat" in the atmosphere solves some of these communications problems and makes it more likely that people will support policies to address global warming.

  20. Erosion and the rocks of Venus

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1976-01-01

    Photographs of the surface of Venus returned by the Venera 9 and 10 spacecraft have revealed the presence of smooth and angular rockline forms. Two mechanisms previously suggested (Sagan, 1975) for erosion of crater ramparts on the surface of Venus might also explain the erosion of rocks. Chemical weathering by the hydrochloric, hydrofluoric, and sulfuric acids present in the atmosphere of Venus may have been sufficient to erode angular projections of silicous rocks. Alternatively, the contours of rocks containing such low-melting materials as NaOH, KOH, HgS and KNO2 may have softened as the result of exposure to the high surface temperatures of the planet.

  1. Seafloor Weathering As a Long-Term Climate Regulation Mechanism

    NASA Astrophysics Data System (ADS)

    Farahat, N. X.; Abbot, D. S.; Archer, D. E.

    2014-12-01

    The global carbon cycle determines the distribution of carbon between the atmosphere, ocean, and solid earth. Carbon from the mantle enters the Earth's surficial environment as CO2 by volcanic outgassing, and carbon is buried in the oceanic crust as carbonate rocks during silicate rock weathering. The subduction of carbonate-rich oceanic plates returns carbon to the mantle, closing the cycle. Subtle adjustments in continental silicate weathering, widely held to consume atmospheric CO2 at a rate controlled by climate, are believed to have maintained habitable conditions throughout Earth's history. This long term climate regulation mechanism is known as a climate-weathering feedback. Seafloor weathering, low-temperature basalt alteration and carbonate precipitation in the permeable upper oceanic crust, has been proposed as a climate-weathering feedback as well, but the link to climate is presently poorly understood. Such a climate regulation mechanism would be particularly important on waterworld planets where continental silicate weathering cannot regulate climate. It has so far not been possible to determine whether changes in seafloor weathering could contribute to climate regulation on Earth or in a waterworld scenario because the necessary modeling framework has not yet been developed. However, advances in porous media flow modeling and reactive transport modeling, as well as the availability of inexpensive computational power, allow the seafloor weathering problem to be looked at in greater detail. We have developed a spatially resolved two-dimmensional (2D) numerical model of seafloor weathering in the permeable upper oceanic crust. This model simulates 2D off-axis hydrothermal flow coupled to geochemical alteration of seafloor basalt by modeling reactive transport of chemical species in seawater-derived hydrothermal fluids. The focus of this research is to use the model to determine the effect of geological and climatic factors on seafloor weathering, which

  2. Weathering of sulfides on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.; Fisher, Duncan S.

    1987-01-01

    Pyrrhotite-pentlandite assemblages in mafic and ultramafic igneous rocks may have contributed significantly to the chemical weathering reactions that produce degradation products in the Martian regolith. By analogy and terrestrial processes, a model is proposed whereby supergene alteration of these primary Fe-Ni sulfides on Mars has generated secondary sulfides (e.g., pyrite) below the water table and produced acidic groundwater containing high concentrations of dissolved Fe, Ni, and sulfate ions. The low pH solutions also initiated weathering reactions of igneous feldspars and ferromagnesian silicates to form clay silicate and ferric oxyhydroxide phases. Near-surface oxidation and hydrolysis of ferric sulfato-and hydroxo-complex ions and sols formed gossan above the water table consisting of poorly crystalline hydrated ferric sulfates (e.g., jarosite), oxides (ferrihydrite, goethite), and silica (opal). Underlying groundwater, now permafrost contains hydroxo sulfato complexes of Fe, Al, Mg, Ni, which may be stabilized in frozen acidic solutions beneath the surface of Mars. Sublimation of permafrost may replenish colloidal ferric oxides, sulfates, and phyllosilicates during dust storms on Mars.

  3. Weather and emotional state

    NASA Astrophysics Data System (ADS)

    Spasova, Z.

    2010-09-01

    Introduction Given the proven effects of weather on the human organism, an attempt to examine its effects on a psychic and emotional level has been made. Emotions affect the bio-tonus, working ability and concentration, hence their significance in various domains of economic life, such as health care, education, transportation, tourism, etc. Data and methods The research has been made in Sofia City within a period of 8 months, using 5 psychological methods (Eysenck Personality Questionnaire (EPQ), State-Trait Anxiety Inventory (STAI), Test for Self-assessment of the emotional state (developed by Wessman and Ricks), Test for evaluation of moods and Test "Self-confidence - Activity - Mood" (developed by the specialists from the Military Academy in Saint Petersburg). The Fiodorov-Chubukov's complex-climatic method was used to characterize meteorological conditions because of the purpose to include in the analysis a maximal number of meteorological elements. 16 weather types are defined in dependence of the meteorological elements values according to this method. Abrupt weather changes from one day to another, defined by the same method, were considered as well. Results and discussions The results obtained by t-test show that the different categories of weather lead to changes in the emotional status, which indicates a character either positive or negative for the organism. The abrupt weather changes, according to expectations, have negative effect on human emotions but only when a transition to the cloudy weather or weather type, classified as "unfavourable" has been realized. The relationship between weather and human emotions is rather complicated since it depends on individual characteristics of people. One of these individual psychological characteristics, marked by the dimension "neuroticism", has a strong effect on emotional reactions in different weather conditions. Emotionally stable individuals are more "protected" to the weather influence on their emotions

  4. Direct quantification of long-term rock nitrogen inputs to temperate forest ecosystems.

    PubMed

    Morford, Scott L; Houlton, Benjamin Z; Dahlgren, Randy A

    2016-01-01

    Sedimentary and metasedimentary rocks contain large reservoirs of fixed nitrogen (N), but questions remain over the importance of rock N weathering inputs in terrestrial ecosystems. Here we provide direct evidence for rock N weathering (i.e., loss of N from rock) in three temperate forest sites residing on a N-rich parent material (820-1050 mg N kg(-1); mica schist) in the Klamath Mountains (northern California and southern Oregon), USA. Our method combines a mass balance model of element addition/ depletion with a procedure for quantifying fixed N in rock minerals, enabling quantification of rock N inputs to bioavailable reservoirs in soil and regolith. Across all sites, -37% to 48% of the initial bedrock N content has undergone long-term weathering in the soil. Combined with regional denudation estimates (sum of physical + chemical erosion), these weathering fractions translate to 1.6-10.7 kg x ha(-1) x yr(-1) of rock N input to these forest ecosystems. These N input fluxes are substantial in light of estimates for atmospheric sources in these sites (4.5-7.0 kg x ha(-1) x yr(-1)). In addition, N depletion from rock minerals was greater than sodium, suggesting active biologically mediated weathering of growth-limiting nutrients compared to nonessential elements. These results point to regional tectonics, biologically mediated weathering effects, and rock N chemistry in shaping the magnitude of rock N inputs to the forest ecosystems examined. PMID:27008775

  5. Iron isotopic fractionation during continental weathering

    SciTech Connect

    Fantle, Matthew S.; DePaolo, Donald J.

    2003-10-01

    The biological activity on continents and the oxygen content of the atmosphere determine the chemical pathways through which Fe is processed at the Earth's surface. Experiments have shown that the relevant chemical pathways fractionate Fe isotopes. Measurements of soils, streams, and deep-sea clay indicate that the {sup 56}Fe/{sup 54}Fe ratio ({delta}{sup 56}Fe relative to igneous rocks) varies from +1{per_thousand} for weathering residues like soils and clays, to -3{per_thousand} for dissolved Fe in streams. These measurements confirm that weathering processes produce substantial fractionation of Fe isotopes in the modern oxidizing Earth surface environment. The results imply that biologically-mediated processes, which preferentially mobilize light Fe isotopes, are critical to Fe chemistry in weathering environments, and that the {delta}{sup 56}Fe of marine dissolved Fe should be variable and negative. Diagenetic reduction of Fe in marine sediments may also be a significant component of the global Fe isotope cycle. Iron isotopes provide a tracer for the influence of biological activity and oxygen in weathering processes through Earth history. Iron isotopic fractionation during weathering may have been smaller or absent in an oxygen-poor environment such as that of the early Precambrian Earth.

  6. Weatherizing a Structure.

    ERIC Educational Resources Information Center

    Metz, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with weatherizing a structure. Its objective is for the student to be able to analyze factors related to specific structures that indicate need for weatherizing activities and to determine steps to correct defects in structures that…

  7. Mild and Wild Weather.

    ERIC Educational Resources Information Center

    NatureScope, 1985

    1985-01-01

    Presents background information and six activities that focus on clouds, precipitation, and stormy weather. Each activity includes an objective, recommended age level(s), subject area(s), and instructional strategies. Also provided are two ready-to-copy pages (a coloring page on lightning and a list of weather riddles to solve). (JN)

  8. People and Weather.

    ERIC Educational Resources Information Center

    NatureScope, 1985

    1985-01-01

    Provides: (1) background information on ways weather influences human lives; (2) activities related to this topic; and (3) a ready-to-copy page with weather trivia. Each activity includes an objective, list of materials needed, recommended age level(s), subject area(s), and instructional strategies. (JN)

  9. World weather program

    NASA Technical Reports Server (NTRS)

    1980-01-01

    A brief description of the Global Weather Experiment is presented. The world weather watch program plan is described and includes a global observing system, a global data processing system, a global telecommunication system, and a voluntary cooperation program. A summary of Federal Agency plans and programs to meet the challenges of international meteorology for the two year period, FY 1980-1981, is presented.

  10. Exercising in Cold Weather

    MedlinePlus

    ... www.nia.nih.gov/Go4Life Exercising in Cold Weather Exercise has benefits all year, even during winter. ... activities when it’s cold outside: l Check the weather forecast. If it’s very windy or cold, exercise ...

  11. Teacher's Weather Sourcebook.

    ERIC Educational Resources Information Center

    Konvicka, Tom

    This book is a teaching resource for the study of weather-related phenomena. A "weather unit" is often incorporated into school study because of its importance to our daily lives and because of its potential to cut across disciplinary content. This book consists of two parts. Part I covers the major topics of atmospheric science such as the modern…

  12. KSC Weather and Research

    NASA Technical Reports Server (NTRS)

    Maier, Launa; Huddleston, Lisa; Smith, Kristin

    2016-01-01

    This briefing outlines the history of Kennedy Space Center (KSC) Weather organization, past research sponsored or performed, current organization, responsibilities, and activities, the evolution of weather support, future technologies, and an update on the status of the buoys located offshore of Cape Canaveral Air Force Station and KSC.

  13. Weather Fundamentals: Clouds. [Videotape].

    ERIC Educational Resources Information Center

    1998

    The videos in this educational series, for grades 4-7, help students understand the science behind weather phenomena through dramatic live-action footage, vivid animated graphics, detailed weather maps, and hands-on experiments. This episode (23 minutes) discusses how clouds form, the different types of clouds, and the important role they play in…

  14. Weathering Database Technology

    ERIC Educational Resources Information Center

    Snyder, Robert

    2005-01-01

    Collecting weather data is a traditional part of a meteorology unit at the middle level. However, making connections between the data and weather conditions can be a challenge. One way to make these connections clearer is to enter the data into a database. This allows students to quickly compare different fields of data and recognize which…

  15. On Observing the Weather

    ERIC Educational Resources Information Center

    Crane, Peter

    2004-01-01

    Rain, sun, snow, sleet, wind... the weather affects everyone in some way every day, and observing weather is a terrific activity to attune children to the natural world. It is also a great way for children to practice skills in gathering and recording information and to learn how to use simple tools in a standardized fashion. What better way to…

  16. Fabulous Weather Day

    ERIC Educational Resources Information Center

    Marshall, Candice; Mogil, H. Michael

    2007-01-01

    Each year, first graders at Kensington Parkwood Elementary School in Kensington, Maryland, look forward to Fabulous Weather Day. Students learn how meteorologists collect data about the weather, how they study wind, temperature, precipitation, basic types/characteristics of clouds, and how they forecast. The project helps the students grow in…

  17. The Home Weather Station.

    ERIC Educational Resources Information Center

    Steinke, Steven D.

    1991-01-01

    Described is how an amateur weather observer measures and records temperature and precipitation at a well-equipped, backyard weather station. Directions for building an instrument shelter and a description of the instruments needed for measuring temperature and precipitation are included. (KR)

  18. Weather Fundamentals: Wind. [Videotape].

    ERIC Educational Resources Information Center

    1998

    The videos in this educational series, for grades 4-7, help students understand the science behind weather phenomena through dramatic live-action footage, vivid animated graphics, detailed weather maps, and hands-on experiments. This episode (23 minutes) describes the roles of the sun, temperature, and air pressure in creating the incredible power…

  19. Aviation Weather Program (AWP)

    NASA Technical Reports Server (NTRS)

    Foote, Brant

    1993-01-01

    The Aviation Weather Program (AWP) combines additional weather observations, improved forecast technology, and more efficient distribution of information to pilots, controllers, and automated systems to improve the weather information provided to the air traffic control system, pilots, and other users of aviation weather information. Specific objectives include the needs to: improve airport and en-route capacity by accurate, high resolution, timely forecasts of changing weather conditions affecting airport and en-route operations; improve analyses and forecasts of upper-level winds for efficient flight planning and traffic management; and increase flight safety through improved aviation weather hazard forecasting (e.g. icing, turbulence, severe storms, microbursts, or strong winds). The AWP would benefit from participation in a cooperative multiscale experiment by obtaining data for: evaluation of aviation weather forecast products, analysis of four dimensional data assimilation schemes, and experimental techniques for retrieving aerosol and other visibility parameters. A multiscale experiment would also be helpful to AWP by making it possible to evaluate the added benefit of enhanced data sets collected during the experiment on those forecast and analysis products. The goals of the Coperative Multiscale Experiment (CME) are an essential step in attaining the long-term AWP objective of providing two-to-four hour location-specific forecasts of significant weather. Although the possibility of a funding role for the AWP in the CME is presently unclear, modest involvement of Federal Aviation Administration (FAA)/AWP personnel could be expected.

  20. Weather and Culture.

    ERIC Educational Resources Information Center

    Contemporary Learning Center, Houston, TX.

    This document is a minicourse on the interaction of weather, environment, and culture. It is designed for the high school student to read and self-administer. Performance objectives, enabling activities, and postassessment questions are given for each of eight modules. The modules are: (1) Basic Facts About Your Weather Known As Rain, (2) The…

  1. Home Weatherization Visit

    ScienceCinema

    Chu, Steven

    2013-05-29

    Secretary Steven Chu visits a home that is in the process of being weatherized in Columbus, OH, along with Ohio Governor Ted Strickland and Columbus Mayor Michael Coleman. They discuss the benefits of weatherization and how funding from the recovery act is having a direct impact in communities across America.

  2. Designing a Weather Station

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2012-01-01

    The collection and analysis of weather data is crucial to the location of alternate energy systems like solar and wind. This article presents a design challenge that gives students a chance to design a weather station to collect data in advance of a large wind turbine installation. Data analysis is a crucial part of any science or engineering…

  3. Poohbear Rock

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image, taken by Sojourner's front right camera, was taken when the rover was next to Poohbear (rock at left) and Piglet (not seen) as it looked out toward Mermaid Dune. The textures differ from the foreground soil containing a sorted mix of small rocks, fines and clods, from the area a bit ahead of the rover where the surface is covered with a bright drift material. Soil experiments where the rover wheels dug in the soil revealed that the cloudy material exists underneath the drift.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  4. Meridiani Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    16 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the complex surfaces of some of the light- and intermediate-toned sedimentary rock exposed by erosion in eastern Sinus Meridiani. Similar rocks occur at the Mars Exploration Rover, Opportunity, site, but they are largely covered by windblown sand and granules. The dark feature with a rayed pattern is the product of a meteor impact.

    Location near: 0.8oN, 355.2oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  5. Terby's Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    25 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary rock outcrops in the crater, Terby. The crater is located on the north rim of Hellas Basin. If one could visit the rocks in Terby, one might learn from them whether they formed in a body of water. It is possible, for example, that Terby was a bay in a larger, Hellas-wide sea.

    Location near: 27.9oS, 285.7oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Winter

  6. White Rock

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 19 April 2002) The Science 'White Rock' is the unofficial name for this unusual landform which was first observed during the Mariner 9 mission in the early 1970's. As later analysis of additional data sets would show, White Rock is neither white nor dense rock. Its apparent brightness arises from the fact that the material surrounding it is so dark. Images from the Mars Global Surveyor MOC camera revealed dark sand dunes surrounding White Rock and on the floor of the troughs within it. Some of these dunes are just apparent in the THEMIS image. Although there was speculation that the material composing White Rock could be salts from an ancient dry lakebed, spectral data from the MGS TES instrument did not support this claim. Instead, the White Rock deposit may be the erosional remnant of a previously more continuous occurrence of air fall sediments, either volcanic ash or windblown dust. The THEMIS image offers new evidence for the idea that the original deposit covered a larger area. Approximately 10 kilometers to the southeast of the main deposit are some tiny knobs of similarly bright material preserved on the floor of a small crater. Given that the eolian erosion of the main White Rock deposit has produced isolated knobs at its edges, it is reasonable to suspect that the more distant outliers are the remnants of a once continuous deposit that stretched at least to this location. The fact that so little remains of the larger deposit suggests that the material is very easily eroded and simply blows away. The Story Fingers of hard, white rock seem to jut out like icy daggers across a moody Martian surface, but appearances can be deceiving. These bright, jagged features are neither white, nor icy, nor even hard and rocky! So what are they, and why are they so different from the surrounding terrain? Scientists know that you can't always trust what your eyes see alone. You have to use other kinds of science instruments to measure things that our eyes can

  7. White Rock

    NASA Technical Reports Server (NTRS)

    2005-01-01

    14 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the famous 'White Rock' feature in Pollack Crater in the Sinus Sabaeus region of Mars. The light-toned rock is not really white, but its light tone caught the eye of Mars geologists as far back as 1972, when it was first spotted in images acquired by Mariner 9. The light-toned materials are probably the remains of a suite of layered sediments that once spread completely across the interior of Pollack Crater. Dark materials in this image include sand dunes and large ripples.

    Location near: 8.1oS, 335.1oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

  8. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains how our weather occurs, and why Solar radiation is responsible. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  9. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains what high and low pressure weather systems are, and how they form. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  10. Hydrologic regulation of chemical weathering and the geologic carbon cycle.

    PubMed

    Maher, K; Chamberlain, C P

    2014-03-28

    Earth's temperature is thought to be regulated by a negative feedback between atmospheric CO2 levels and chemical weathering of silicate rocks that operates over million-year time scales. To explain variations in the strength of the weathering feedback, we present a model for silicate weathering that regulates climatic and tectonic forcing through hydrologic processes and imposes a thermodynamic limit on weathering fluxes, based on the physical and chemical properties of river basins. Climate regulation by silicate weathering is thus strongest when global topography is elevated, similar to the situation today, and lowest when global topography is more subdued, allowing planetary temperatures to vary depending on the global distribution of topography and mountain belts, even in the absence of appreciable changes in CO2 degassing rates. PMID:24625927

  11. Carbonate weathering along a climatic gradient in the Jura Mountains

    NASA Astrophysics Data System (ADS)

    Gaillardet, J.; Calmels, D.; Francois, L. M.

    2013-12-01

    A significant portion of the Critical Zone of the Earth is developed on carbonate rocks. In order to investigate the control of carbonate weathering and in particular its response to climate change, we sampled rivers and springs in a well-drained pure carbonate area subjected to strong environmental gradients, the Jura Mountains, Western Europe. The intensity of carbonate weathering, shows a gradual two-fold increase with decreasing elevation from 1200m to 300m. These changes cannot be interpreted in terms of thermodynamic equilibrium and changes of the thermodynamic constants with temperature. The change in vegetation species from deciduous forest in plains to coniferous forest in altitude appears as a major control. Using the ecological and hydrological ASPECTS model, we show that the availability of soil CO2, known as a main weathering agent of rocks, is directly linked to the spatial distribution of vegetation species over the study area. The type of vegetation drives temporal and spatial variations of the carbon and water budgets in soils and therefore partly controls both carbonate weathering intensity and rates. At a given runoff, carbonate weathering rates are classically 20-30% higher under deciduous vegetation cover than under coniferous forest. This study demonstrates that carbonate weathering is strongly sensitive to the ecosystem dynamics, a conclusion that may be much more general, and suggests that carbonate weathering quickly reacts to any global change and/or land use modification.

  12. Geochemistry of large river suspended sediments: Silicate weathering or recycling tracer?

    SciTech Connect

    Gaillardet, J.; Dupre, B.; Allegre, C.J.

    1999-12-01

    This study focuses on the major and trace element composition of suspended sediments transported by the world's largest rivers. Its main purpose is to answer the following question: is the degree of weathering of modern river-borne particles consistent with the estimated river dissolved loads derived from silicate weathering? In agreement with the well known mobility of elements during weathering of continental rocks, the authors confirm that river sediments are systematically depleted in Na, K, Ba with respect to the Upper Continental Crust. For each of these mobile elements, a systematics of weathering indexes of river-borne solids is attempted. A global consistency is found between all these indexes. Important variations in weathering intensities exist. A clear dependence of weathering intensities with climate is observed for the rivers draining mostly lowlands. However, no global correlation exists between weathering intensities and climatic or relief parameters because the trend observed for lowlands is obscured by rivers draining orogenic zones. An inverse correlation between weathering intensities and suspended sediment concentrations is observed showing that the regions having the highest rates of physical denudation produce the least weathered sediments. Finally, chemical and physical weathering are compared through the use of a simple steady state model. The authors show that the weathering intensities of large river suspended sediments can only be reconciled with the (silicate-derived) dissolved load or rivers, by admitting that most of the continental rocks submitted to weathering in large river basins have already suffered previous weathering cycles. A simple graphical method is proposed for calculating the proportion of sedimentary recycling in large river basins. Finally, even if orogenic zones produce weakly weathered sediments, the authors emphasize the fact that silicate chemical weathering rates (and hence CO{sub 2} consumption rates by silicate

  13. The Space Weather Reanalysis

    NASA Astrophysics Data System (ADS)

    Kihn, E. A.; Ridley, A. J.; Zhizhin, M.

    2002-12-01

    The objective of this project is to generate a complete 11 year space weather representation using physically consistent data-driven space weather models. The project will create a consistent, integrated historical record of the near Earth space environment by coupling observational data from space environmental monitoring systems archived at NGDC with data-driven, physically based numerical models. The resulting product will be an enhanced look at the space environment on consistent grids, time resolution, coordinate systems and containing key fields allowing an interested user to quickly and easily incorporate the impact of the near-Earth space climate in environmentally sensitive models. Currently there are no easily accessible long term climate archives available for the space-weather environment. Just as with terrestrial weather it is crucial to understand both daily weather forecasts as well as long term climate changes, so this project will demonstrate the ability to generate a meaningful and physically derived space weather climatology. The results of this project strongly support the DOD's Environmental Scenario Generator (ESG) project. The ESG project provides tools for intellegent data mining, classification and event detection which could be applied to a historical space-weather database. The two projects together provide a suite of tools for the user interested in modeling the effect of the near-earth space environment. We will present results and methodologies developed during the first two years of effort in the project.

  14. Environmental Education Tips: Weather Activities.

    ERIC Educational Resources Information Center

    Brainard, Audrey H.

    1989-01-01

    Provides weather activities including questions, on weather, heating the earth's surface, air, tools of the meteorologist, clouds, humidity, wind, and evaporation. Shows an example of a weather chart activity. (RT)

  15. Weather--An Integrated Unit

    ERIC Educational Resources Information Center

    McConnell, Vivian

    1976-01-01

    Outlined is a two week unit on weather offered as independent study for sixth- and seventh-year students in Vancouver, Canada, schools. Included is a section on weather lore and a chart of weather symbols. (SL)

  16. Food Safety for Warmer Weather

    MedlinePlus

    ... Fight Off Food Poisoning Food Safety for Warmer Weather In warm-weather months, who doesn’t love to get outside ... to keep foods safe to eat during warmer weather. If you’re eating or preparing foods outside, ...

  17. Hypothermia: A Cold Weather Hazard

    MedlinePlus

    ... Weather Hazard Heath and Aging Hypothermia: A Cold Weather Hazard What Are The Signs Of Hypothermia? Taking ... cold air. But, not everyone knows that cold weather can also lower the temperature inside your body. ...

  18. Release of biodegradable dissolved organic matter from ancient sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Schillawski, Sarah; Petsch, Steven

    2008-09-01

    Sedimentary rocks contain the largest mass of organic carbon on Earth, yet these reservoirs are not well integrated into modern carbon budgets. Here we describe the release of dissolved organic matter (DOM) from OM-rich sedimentary rocks under simulated weathering conditions. Results from column experiments demonstrate slow, sustained release of DOM from ancient sedimentary rocks under simulated weathering conditions. 1H-NMR analysis of shale-derived DOM reveals a highly aliphatic, carbohydrate-poor material distinct from other natural DOM pools. Shale-derived DOM is rapidly assimilated and biodegraded by aerobic heterotrophic bacteria. Consequently, no compositional signature of shale-derived DOM other than 14C-depletion is likely to persist in rivers or other surface reservoirs. Combined, these efforts show that dissolution provides a mechanism for the conversion of refractory kerogen into labile biomass, linking rock weathering with sedimentary OM oxidation and the delivery of aged OM to rivers and ocean margins.

  19. Sun, weather, and climate

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Goldberg, R. A.

    1985-01-01

    The general field of sun-weather/climate relationships, that is, apparent weather and climate responses to solar activity is introduced and theoretical and experimental suggestions for further research to identify and investigate the unknown causal mechanisms are provided. Topics of discussion include: (1) solar-related correlation factors and energy sources; (2) long-term climatic trends; (3) short-term meteorological correlations; (4) miscellaneous obscuring influences; (5) physical processes and mechanisms; (6) recapitulation of sun-weather relationships; and (7) guidelines for experiments.

  20. Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    6 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcrops of sedimentary rocks in a crater located just north of the Sinus Meridiani region. Perhaps the crater was once the site of a martian lake.

    Location near: 2.9oN, 359.0oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  1. Thermal Inertia of Rocks and Rock Populations

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Jakosky, B. M.; Mellon, M. T.

    2001-01-01

    The effective thermal inertia of rock populations on Mars and Earth is derived from a model of effective inertia versus rock diameter. Results allow a parameterization of the effective rock inertia versus rock abundance and bulk and fine component inertia. Additional information is contained in the original extended abstract.

  2. From Rocks to Cement. What We Make. Science and Technology Education in Philippine Society.

    ERIC Educational Resources Information Center

    Philippines Univ., Quezon City. Science Education Center.

    This module deals with the materials used in making concrete hollow blocks. Topics discussed include: (1) igneous, metamorphic, and sedimentary rocks; (2) weathering (the process of breaking down rocks) and its effects on rocks; (3) cement; (4) stages in the manufacturing of Portland cement; and (5) the transformation of cement into concrete…

  3. Redistribution of uranium and thorium series isotopes during isovolumetric weathering of granite

    NASA Astrophysics Data System (ADS)

    Michel, Jacqueline

    1984-06-01

    Previous studies of the distribution of U and Th in parent versus weathered granites have shown both depletion and enrichment of these elements during weathering. In this study, the distribution of U and Th decay series isotopes was determined in a weathering profile of a granitic saprolite, which showed textural preservation indicating isovolumetric weathering. Two types of dissolution methods were used: a whole-rock dissolution and a sodium-citrate dithionite leach to preferentially attack noncrystalline phases of weathering products. Using volume-based activities, 45-70 percent of the total 232Th was gradually removed during weathering. Although the whole-rock 228Th /232Th activity ratios were in equilibrium, there were large excesses of 228Th in the leachable fraction of both parent rock ( 228Th /232Th = 2.06 ) and partially weathered saprolite ( 228Th /232Th = 3-6.5 ), due to alpha recoil and release of daughter 228Th to the weathering rind of the mineral grain. For the most weathered sample, 81 percent of the thorium was in the teachable fraction and 228Th /232Th = 1 , indicating that even the more resistant minerals were attacked. The total U activities showed as much variation in the six parent rock samples as in the weathered profile, and 234U /238U were in equilibrium in both the whole-rock and leachable fractions. 230Th was deficient relative to 234U and 226Ra in both fractions, suggesting recent addition of U and Ra to the entire profile. The large variation in U was not from absorption onto the intermediate weathering products, because only 11-23 percent of the U was in the leachable fraction.

  4. Weathering in a Cup.

    ERIC Educational Resources Information Center

    Stadum, Carol J.

    1991-01-01

    Two easy student activities that demonstrate physical weathering by expansion are described. The first demonstrates ice wedging and the second root wedging. A list of the needed materials, procedure, and observations are included. (KR)

  5. Weathering of Martian Evaporites

    NASA Technical Reports Server (NTRS)

    Wentworth, S. J.; Velbel, M. A.; Thomas-Keprta, K. L.; Longazo, T. G.; McKay, D. S.

    2001-01-01

    Evaporites in martian meteorites contain weathering or alteration features that may provide clues about the martian near-surface environment over time. Additional information is contained in the original extended abstract.

  6. Waste glass weathering

    SciTech Connect

    Bates, J.K.; Buck, E.C.

    1993-12-31

    The weathering of glass is reviewed by examining processes that affect the reaction of commercial, historical, natural, and nuclear waste glass under conditions of contact with humid air and slowly dripping water, which may lead to immersion in nearly static solution. Radionuclide release data from weathered glass under conditions that may exist in an unsaturated environment are presented and compared to release under standard leaching conditions. While the comparison between the release under weathering and leaching conditions is not exact, due to variability of reaction in humid air, evidence is presented of radionuclide release under a variety of conditions. These results suggest that both the amount and form of radionuclide release can be affected by the weathering of glass.

  7. Americans and Their Weather

    NASA Astrophysics Data System (ADS)

    Meyer, William B.

    2000-07-01

    This revealing book synthesizes research from many fields to offer the first complete history of the roles played by weather and climate in American life from colonial times to the present. Author William B. Meyer characterizes weather events as neutral phenomena that are inherently neither hazards nor resources, but can become either depending on the activities with which they interact. Meyer documents the ways in which different kinds of weather throughout history have represented hazards and resources not only for such exposed outdoor pursuits as agriculture, warfare, transportation, construction, and recreation, but for other realms of life ranging from manufacturing to migration to human health. He points out that while the weather and climate by themselves have never determined the course of human events, their significance as been continuously altered for better and for worse by the evolution of American life.

  8. Weather Information Processing

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Science Communications International (SCI), formerly General Science Corporation, has developed several commercial products based upon experience acquired as a NASA Contractor. Among them are METPRO, a meteorological data acquisition and processing system, which has been widely used, RISKPRO, an environmental assessment system, and MAPPRO, a geographic information system. METPRO software is used to collect weather data from satellites, ground-based observation systems and radio weather broadcasts to generate weather maps, enabling potential disaster areas to receive advance warning. GSC's initial work for NASA Goddard Space Flight Center resulted in METPAK, a weather satellite data analysis system. METPAK led to the commercial METPRO system. The company also provides data to other government agencies, U.S. embassies and foreign countries.

  9. Rock Driller

    NASA Technical Reports Server (NTRS)

    Peterson, Thomas M.

    2001-01-01

    The next series of planetary exploration missions require a method of extracting rock and soil core samples. Therefore a prototype ultrasonic core driller (UTCD) was developed to meet the constraints of Small Bodies Exploration and Mars Sample Return Missions. The constraints in the design are size, weight, power, and axial loading. The ultrasonic transducer requires a relatively low axial load, which is one of the reasons this technology was chosen. The ultrasonic generator breadboard section can be contained within the 5x5x3 limits and weighs less than two pounds. Based on results attained the objectives for the first phase were achieved. A number of transducer probes were made and tested. One version only drills, and the other will actually provide a small core from a rock. Because of a more efficient transducer/probe, it will run at very low power (less than 5 Watts) and still drill/core. The prototype generator was built to allow for variation of all the performance-effecting elements of the transducer/probe/end effector, i.e., pulse, duty cycle, frequency, etc. The heart of the circuitry is what will be converted to a surface mounted board for the next phase, after all the parameters have been optimized and the microprocessor feedback can be installed.

  10. Salt weathering on Mars

    NASA Technical Reports Server (NTRS)

    Malin, M. C.

    1974-01-01

    Mariner 9 photographs of Mars indicate that significant erosion has occurred on that planet. Although several possible erosion mechanisms have been proposed, most terrestrial weathering mechanisms cannot function in the present Martian environment. Salt weathering, believed to be active in the Antarctic dry valleys, is especially suited to Mars, given the presence of salts and small amounts of water. Volcanic salts are probably available, and the association of salts and water is likely from both thermodynamic and geologic considerations.