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Sample records for accretionary lapilli ash

  1. Experimental volcanic ash aggregation: Internal structuring of accretionary lapilli and the role of liquid bonding

    NASA Astrophysics Data System (ADS)

    Mueller, Sebastian B.; Kueppers, Ulrich; Ayris, Paul M.; Jacob, Michael; Dingwell, Donald B.

    2016-01-01

    Explosive volcanic eruptions can release vast quantities of pyroclastic material into Earth's atmosphere, including volcanic ash, particles with diameters less than two millimeters. Ash particles can cluster together to form aggregates, in some cases reaching up to several centimeters in size. Aggregation alters ash transport and settling behavior compared to un-aggregated particles, influencing ash distribution and deposit stratigraphy. Accretionary lapilli, the most commonly preserved type of aggregates within the geologic record, can exhibit complex internal stratigraphy. The processes involved in the formation and preservation of these aggregates remain poorly constrained quantitatively. In this study, we simulate the variable gas-particle flow conditions which may be encountered within eruption plumes and pyroclastic density currents via laboratory experiments using the ProCell Lab System® of Glatt Ingenieurtechnik GmbH. In this apparatus, solid particles are set into motion in a fluidized bed over a range of well-controlled boundary conditions (particle concentration, air flow rate, gas temperature, humidity, liquid composition). Experiments were conducted with soda-lime glass beads and natural volcanic ash particles under a range of experimental conditions. Both glass beads and volcanic ash exhibited the capacity for aggregation, but stable aggregates could only be produced when materials were coated with high but volcanically-relevant concentrations of NaCl. The growth and structure of aggregates was dependent on the initial granulometry, while the rate of aggregate formation increased exponentially with increasing relative humidity (12-45% RH), before overwetting promoted mud droplet formation. Notably, by use of a broad granulometry, we generated spherical, internally structured aggregates similar to some accretionary pellets found in volcanic deposits. Adaptation of a powder-technology model offers an explanation for the origin of natural accretionary

  2. Origin of accretionary lapilli from the Pompeii and Avellino deposits of Vesuvius

    SciTech Connect

    Sheridan, M.F.; Wohletz, K.H.

    1983-01-01

    Accretionary lapilli from the Pompeii and Avellino Plinian ash deposits of Vesuvius consist of centimeter-sized spheroids composed of glass, crystal, and lithic fragments of submillimeter size. The typical structure of the lapilli consists of a central massive core surrounded by concentric layers of fine ash with concentrations of larger clasts and vesicles and a thin outer layer of dust. Clasts within the lapilli larger than 125 ..mu..m are extremely rare. The median grain-size of the fine ash is about 50 ..mu..m and the size-distribution is well sorted. Most constituent particles of accretionary lapilli display blocky shapes characteristic of grains produced by phreatomagmatic hydroexplosions. We have used the scanning electron microscope (SEM) in conjunction with energy dispersive spectral analysis (EDS) to investigate the textural and chemical variation along traverses from the core to the rim of lapilli from Vesuvius.

  3. Accretionary lapilli: what’s holding them together?

    USGS Publications Warehouse

    Adams, Paul M.; Lynch, David K.; Buesch, David C.

    2016-01-01

    Accretionary lapilli from Tagus cone, Isla Isabela, Galápagos were analyzed using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. Our main findings are (1) the lapilli formed and hardened in a few minutes while still aloft in the dispersing eruption column. (2) Palagonite rinds developed first on the basaltic glass clasts, and subsequently crystallized (3) The crystallization products contain submicron lamellar crystals of a clay (probably smectite) on the surfaces of basaltic glass clasts and (4) The interlocking of these lamellar clays from adjacent clasts binds and cements them together to form the accretionary lapillus. We argue that palagonite and possibly clay formation occur primarily in the presence of hot water vapor.

  4. Accretionary lapilli, tektites, or concretions: the ubiquitous spherules of Meridiani Planum

    NASA Astrophysics Data System (ADS)

    DiGregorio, Barry E.

    2004-11-01

    One of the most enigmatic discoveries made by the NASA Mars Exploration Rover Opportunity (MER-B) at the Meridiani Planum landing site are the ubiquitous spherules referred to as "blueberries" by the science team. They cover the entire landing area and can be seen in every direction within view of the rover cameras. Subsequent analysis of a small grouping of the spherules laying on top of a rock outcrop by Mossbauer spectroscopy showed an intense hematite signature not found on the rock or in the surrounding basaltic soils. Spherules were also found attached to and embedded within sedimentary sulfate rock outcrops found at the landing area that have been determined by the MER science team as having been formed in an acidic liquid water environment. The appearance of most of the Meridiani spherules is strikingly similar to the morphology and size of terrestrial accretionary lapilli and show similarities to terrestrial tektites. Accretionary lapilli are spherical balls and fragments with a concentric layered structure that are formed by a variety of mechanisms including hydrovolcanic eruptions, geysers and large meteorite impacts in water. Tektites are glassy impact spherules that form as a result of large meteorite impacts and also seem apparent in some of the rover images. Tektites can be perfectly spherical or have teardrop and dumbbell shapes. A lack of a visible volcanic source capable of producing high volumes of accretionary lapilli as seen in the MER-B images, in combination with the strong spectral signature of hematite, that some of the spherules display, led the MER science team to favor a concretion hypothesis thus far. All of these types of spherules involve interaction of with surface water or ice to form. Problems exist in explaining how the Martian "concretions", if that is indeed what they are, are of such uniform size and have such a wide distribution. Evidence from Martian orbit and on the surface indicate that the Meridiani Planum landing ellipse

  5. Armoured lapilli in glaciovolcanic deposits: origins and implications

    NASA Astrophysics Data System (ADS)

    Ryane, C.; Russell, K.; Edwards, B. R.; Porritt, L. A.

    2011-12-01

    Accretionary lapilli are common products of volcanic eruptions and their presence is important for constraining eruption conditions. Armoured lapilli, a specific type of accretionary lapilli featuring discrete cores coated by ash occur within the proximal pyroclastic deposits of Kima'Kho tuya, northern B.C., Canada. The armoured lapilli are absent from the lowermost portions of the pyroclastic succession but are pervasive in the upper third of the sequence. They occur in two modes: i) within massive lapilli tuff as dispersed, isolated pyroclasts, or ii) concentrated in cm-scale beds. Petrographic and textural analysis of the armoured lapilli shows them to comprise a central 2-30 mm-sized, juvenile, vesiculated pyroclast, concentrically coated by mm-scale layers of 10-250 μm sized ash particles. At Kima'Kho, the armoured lapilli are shown to be a direct indicator of fallout from a sustained plume attended by concomitant production of pyroclastic density currents. Their size and internal structure provide constraints on the nature of the initial explosive phase of eruption at Kima'Kho. Plume heights estimated from armoured lapilli dimensions are inversely proportional to plume mass loadings. Plume heights, assuming accretion on both upward and downward trajectories, are inferred to be between 1 km (mass loading value 50 x 10-3 kg/m3) and 10 km (mass loading value 6 x 10-3 kg/m3). Lastly, the presence of armoured lapilli at Kima'Kho is critical because their preservation indicates an emergent, subaerial phase of the subglacial eruption and deposition above an englacial lake 370 m in depth, defining a previously undescribed style of 'passage zone'.

  6. Ash Aggregates in Proximal Settings

    NASA Astrophysics Data System (ADS)

    Porritt, L. A.; Russell, K.

    2012-12-01

    Ash aggregates are thought to have formed within and been deposited by the eruption column and plume and dilute density currents and their associated ash clouds. Moist, turbulent ash clouds are considered critical to ash aggregate formation by facilitating both collision and adhesion of particles. Consequently, they are most commonly found in distal deposits. Proximal deposits containing ash aggregates are less commonly observed but do occur. Here we describe two occurrences of vent proximal ash aggregate-rich deposits; the first within a kimberlite pipe where coated ash pellets and accretionary lapilli are found within the intra-vent sequence; and the second in a glaciovolcanic setting where cored pellets (armoured lapilli) occur within <1 km of the vent. The deposits within the A418 pipe, Diavik Diamond Mine, Canada, are the residual deposits within the conduit and vent of the volcano and are characterised by an abundance of ash aggregates. Coated ash pellets are dominant but are followed in abundance by ash pellets, accretionary lapilli and rare cored pellets. The coated ash pellets typically range from 1 - 5 mm in diameter and have core to rim ratios of approximately 10:1. The formation and preservation of these aggregates elucidates the style and nature of the explosive phase of kimberlite eruption at A418 (and other pipes?). First, these pyroclasts dictate the intensity of the kimberlite eruption; it must be energetic enough to cause intense fragmentation of the kimberlite to produce a substantial volume of very fine ash (<62 μm). Secondly, the ash aggregates indicate the involvement of moisture coupled with the presence of dilute expanded eruption clouds. The structure and distribution of these deposits throughout the kimberlite conduit demand that aggregation and deposition operate entirely within the confines of the vent; this indicates that aggregation is a rapid process. Ash aggregates within glaciovolcanic sequences are also rarely documented. The

  7. Role of Water and Ice in Ash Aggregation: Constraints from the Upper Scoriae 1 Deposit, Santorini, Greece.

    NASA Astrophysics Data System (ADS)

    Durant, A. J.; Ernst, G. G.

    2001-12-01

    Volcanic eruption clouds can disperse ash over large areas, posing hazards on the ground and for air traffic. One distant goal is to develop much needed risk models of ash fallout. This however, is hindered by incompletely understood aspects, one of which is ash aggregation and especially the role of liquid water and ice. We analysed accretionary lapilli-rich fall deposits from Santorini, interpreted here to have formed from eruption clouds elutriated from energetic base surges rich in water, which condensed and froze during rise while interacting with ash. Investigation methods included fieldwork, hand sample binocular microscopy, lapilli and particle size analysis, SEM, EPMA and basic modelling of aggregate settling. Field data indicate both ductile and brittle deformation of aggregates during deposition. Lapilli size distributions peak sharply at 2.5 mm with few aggregates ~10 mm, but most <4.5 mm. Lapilli display a volumetrically-dominant, poorly sorted, coarse-grained core and a thin, fine-grained rim. Particle size distributions in the core and rim peak at 45-70 microns and 10-30 microns (MALVERN and SEM data), with a sharp grain size break. This is consistent with growth by wet collection where aggregate size is limited by `drop break-up'. Fine ash rims imply freezing halts wet accretion, and lapilli >4.5 mm indicate accretion proceeds similar to hailstone growth. Insights from hailstone studies and experiments of Gilbert & Lane (1994) suggest that a liquid skin is needed to aggregate fine rim ash, thus constraining rimming processes to approximately 5-8 km asl. Multiple fine rims indicate recycling of frozen accretionary lapilli. Close association of fine vesiculated ash and large lapilli (i.e. contrasting Vt) in the deposit suggests that fallout of lapilli and mud rain was coeval, perhaps due to a settling-driven instability at the umbrella base. A new conceptual model accounting for all data observations is summarised. The new constraints will be useful

  8. Experimentally constraining the boundary conditions for volcanic ash aggregation

    NASA Astrophysics Data System (ADS)

    Kueppers, U.; Auer, B.; Cimarelli, C.; Scolamacchia, T.; Guenthel, M.; Dingwell, D. B.

    2011-12-01

    Volcanic ash is the primary product of various volcanic processes. Due to its size, ash can remain in the atmosphere for a prolonged period of time. Aggregation processes are a first-order influence on the residence time of ash in the atmosphere and its dispersion from the vent. Due to their internal structure, ash aggregates have been classified as ash pellets or accretionary lapilli. Although several concomitant factors may play a role during aggregation, there is a broad consensus that both 1) particle collision and 2) humidity are required for particles to aggregate. However, direct observation of settling aggregates and record of the boundary conditions favourable to their formation are rare, therefore limiting our understanding of the key processes that determine ash aggregates formation. Here, we present the first results from experiments aimed at reproducing ash aggregation by constraining the required boundary conditions. We used a ProCell Lab System of Glatt Ingenieurtechnik GmbH that is conventionally used for food and chemical applications. We varied the following parameters: 1) air flow speed [40-120 m3/h], 2) air temperature [30-60°C], 3) relative humidity [20-50 %], and 4) liquid droplets composition [water and 25% water glass, Na2SiO3]. The starting material (125-90 μm) is obtained by milling natural basaltic lapilli (Etna, Italy). We found that the experimental duration and the chosen conditions were not favourable for the production of stable aggregates when using water as spraying liquid. Using a 25% water-glass solution as binder we could successfully generate and investigate aggregates of up to 2 mm size. Many aggregates are spherical and resemble ash pellets. In nature, ash pellets and accretionary lapilli are the product of complex processes taking place at very different conditions (temperature, humidity, ash concentration, degree of turbulence). These experiments shed some first light on the ash agglomeration process for which direct

  9. Mineralogy of Juvenile Lapilli in Fort a la Corne Pyroclastic Kimberlites

    NASA Astrophysics Data System (ADS)

    Mitchell, R. H.; Kjarsgaard, B. A.; McBride, J.

    2009-05-01

    Pyroclastic-dominated kimberlites of the Fort a la Corne area (Saskatchewan, Canada) are characterized by the presence of juvenile ash and lapilli tuffs together with crystal tuffs composed of discrete crystals of olivine. Juvenile lapilli are amoeboid-to-curviplanar in shape and composed of olivine set in a fine-grained groundmass. Welding of juvenile lapilli is extremely rare. Clasts can be set in a matrix of calcite and/or serpentine. Commonly, olivine crystals protrude from the clast margins. Many, but not all, clasts contain vesicles filled with carbonates and/or serpentine. Carbonates in the vesicles include Sr-bearing calcite, dolomite and Ba-Mg carbonate. Individual kimberlite units in some instances contain several juxtaposed texturally- and mineralogically-different varieties of juvenile lapilli. In others, clasts are of similar petrographic character that differ in only in their spinel mineralogy. In many clasts early-forming microphenocrystal prisms of calcite are present. The groundmass of the ash and lapilli consists of perovskite, serpentine pseudomorphs after monticellite, diverse discrete euhedral, resorbed and atoll spinels, apatite, serpentine, and laths of quench dolomite. Groundmass mica appears to be absent. Spinel assemblages differ between different vents. At Candle Lake the overall trend of spinel compositions follows that typical of hypabyssal kimberlites with individual clasts within a given unit exhibiting segments of this trend. Compositions belong to a spinel- magnesiochromite-chromite-qandilite-magnetite solid solution series. At Smeaton (FALC 169 body), spinel compositions follow the same overall trend but are all relatively more evolved, and typically Ti-rich and Cr-poor. The majority of compositions plot on the rear face of the reduced spinel prism and belong to the spinel- qandilite-ulvospinel-magnetite series. It is concluded that spinels in Fort a la Corne kimberlites follow the "normal" evolutionary trend of spinel compositions

  10. Flotation Experiments with Seafloor-Sampled Pumice Lapilli, IODP 340 - Preliminary Results

    NASA Astrophysics Data System (ADS)

    Jutzeler, M.; Manga, M.; White, J. D.

    2012-12-01

    A 1.25-m-thick, unconsolidated unit of pink pumice lapilli was recovered at site U1396, IODP expedition 340. The drilling site lies at the top of an entirely submarine ridge in a back-arc of the Lesser Antilles volcanic arc, 35 km offshore from Montserrat Island. The unit was recovered from 122 m below sea floor, at a water depth of ~800 m. Preliminary biostratigraphy and paleomagnetic analysis yield an age of ~4 Ma. This age is much older than any rocks from the island of Montserrat, suggesting that the pumice lapilli unit may have submarine origin. In addition, the pumice lapilli unit has a grading and sorting that does not match conventional eruption-fed products from air-fall or turbidity currents. The pumice lapilli unit was recovered at two holes 40 m apart, and is identical in the two cores. The change in grain size in the stratigraphy of the unit defines a weak stratification. The pumice lapilli unit comprises two main sub-units, with four ash-rich intervals. The lower sub-unit is ~20 cm thick, framework-supported, and dominated by angular white tube-pumice lapilli (2-4 mm); dense lithic clasts (2 mm) are concentrated at the base of this sub-unit. The upper sub-unit is 1 m thick, and mostly composed of angular to sub-angular, white tube pumice lapilli (average 4 mm, max 32 mm), in a pink ash matrix. The ash is chiefly composed of micro-pumice clasts, feldspar and ferromagnesian crystal fragments, glass shards, and lithic clasts that commonly contain fresh pyrite. Three main parameters constrain the floatability of pumice clasts in water: vesicularity, clast size and shape, and clast temperature. The connected vesicularity of the pumice clasts was measured by subtracting the weight of dry pumice clasts from their water-saturated weight, and by functional stereology applied on SEM images. Clast-size distribution and clast shape were measured by particle size analyzer (CILAS) and sieving. We carried out pyroclast flotation and settling experiments in an

  11. Environmentally-mediated ash aggregate formation: example from Tungurahua volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Kueppers, Ulrich; Ayris, Paul M.; Bernard, Benjamin; Delmelle, Pierre; Douillet, Guilhem A.; Lavallée, Yan; Mueller, Sebastian B.; Dingwell, Donald B.; Dobson, Kate J.

    2016-04-01

    Volcanic ash is generated during explosive eruptions through an array of different processes; it can be produced in large quantities and can, in some circumstances, have the potential for far-reaching impacts beyond the flanks of the volcano. Aggregation of ash particles can significantly impact the dispersal within the atmosphere, and its subsequent deposition into terrestrial or aquatic environments. However, our understanding of the complex interplay of the boundary conditions which permit aggregation to occur remain incomplete. Tungurahua volcano, Ecuador, has been intermittently active since 1999. In August 2006, a series of pyroclastic density currents (PDC) were generated during a series of dry, Vulcanian explosions and travelled down the western and northern flanks of the volcano. In some locations, the related PDC deposits temporarily dammed the Chambo river, and the residual heat within those deposits produced vigorous steam plumes. During several field campaigns (2009-2015), we mapped, sampled, and analysed the related deposits. At the base of the Rea ravine, a large delta fan of PDC deposits had dammed the river over a length of several hundred metres. In several outcrops adjacent to the river and in small erosional gullies we found a peculiar stratigraphic layer (up to ten centimetres thick) at the top of the PDC deposits. As this layer is capped by a thin fall unit of coarse ash that we also find elsewhere at the top of the August 2006 deposits, the primary nature is without doubt. In this unit, we observed abundant ash aggregates up to eight millimetres in diameter within a poorly sorted, ash-depleted lapilli tuff, primarily comprised of rounded pumiceous and scoriaceous clasts of similar size. Leaching experiments have shown that these aggregates contain several hundred ppm of soluble sulphate and chloride salts. Recent laboratory experiments (Mueller et al. 2015) have suggested that in order for accretionary lapilli to be preserved within ash

  12. The origin of pelletal lapilli in explosive kimberlite eruptions.

    PubMed

    Gernon, T M; Brown, R J; Tait, M A; Hincks, T K

    2012-05-15

    Kimberlites are volatile-rich magmas from mantle depths of ≥ 150  km and are the primary source of diamonds. Kimberlite volcanism involves the formation of diverging pipes or diatremes, which are the locus of high-intensity explosive eruptions. A conspicuous and previously enigmatic feature of diatreme fills are 'pelletal lapilli'--well-rounded clasts consisting of an inner 'seed' particle with a complex rim, thought to represent quenched juvenile melt. Here we show that these coincide with a transition from magmatic to pyroclastic behaviour, thus offering fundamental insights into eruption dynamics and constraints on vent conditions. We propose that pelletal lapilli are formed when fluid melts intrude into earlier volcaniclastic infill close to the diatreme root zone. Intensive degassing produces a gas jet in which locally scavenged particles are simultaneously fluidised and coated by a spray of low-viscosity melt. A similar origin may apply to pelletal lapilli in other alkaline volcanic rocks, including carbonatites, kamafugites and melilitites.

  13. The origin of pelletal lapilli in explosive kimberlite eruptions.

    PubMed

    Gernon, T M; Brown, R J; Tait, M A; Hincks, T K

    2012-01-01

    Kimberlites are volatile-rich magmas from mantle depths of ≥ 150  km and are the primary source of diamonds. Kimberlite volcanism involves the formation of diverging pipes or diatremes, which are the locus of high-intensity explosive eruptions. A conspicuous and previously enigmatic feature of diatreme fills are 'pelletal lapilli'--well-rounded clasts consisting of an inner 'seed' particle with a complex rim, thought to represent quenched juvenile melt. Here we show that these coincide with a transition from magmatic to pyroclastic behaviour, thus offering fundamental insights into eruption dynamics and constraints on vent conditions. We propose that pelletal lapilli are formed when fluid melts intrude into earlier volcaniclastic infill close to the diatreme root zone. Intensive degassing produces a gas jet in which locally scavenged particles are simultaneously fluidised and coated by a spray of low-viscosity melt. A similar origin may apply to pelletal lapilli in other alkaline volcanic rocks, including carbonatites, kamafugites and melilitites. PMID:22588294

  14. Phreatomagmatic and phreatic fall and surge deposits from explosions at Kilauea volcano, Hawaii, 1790 a.d.: Keanakakoi Ash Member

    USGS Publications Warehouse

    McPhie, J.; Walker, G.P.L.; Christiansen, R.L.

    1990-01-01

    In or around 1790 a.d. an explosive eruption took place in the summit caldera of Kilauea shield volcano. A group of Hawaiian warriors close to the caldera at the time were killed by the effects of the explosions. The stratigraphy of pyroclastic deposits surrounding Kilauea (i.e., the Keanakakoi Ash Member) suggests that the explosions referred to in the historic record were the culmination of a prolonged hydrovolcanic eruption consisting of three main phases. The first phase was phreatomagmatic and generated well-bedded, fine fallout ash rich in glassy, variably vesiculated, juvenile magmatic and dense, lithic pyroclasts. The ash was mainly dispersed to the southwest of the caldera by the northeasterly trade winds. The second phase produced a Strombolian-style scoria fall deposit followed by phreatomagmatic ash similar to that of the first phase, though richer in accretionary lapilli and lithics. The third and culminating phase was phreatic and deposited lithic-rich lapilli and block fall layers, interbedded with cross-bedded surge deposits, and accretionary lapilli-rich, fine ash beds. These final explosions may have been responsible for the deaths of the warriors. The three phases were separated by quiescent spells during which the primary deposits were eroded and transported downwind in dunes migrating southwestward and locally excavated by fluvial runoff close to the rim. The entire hydrovolcanic eruption may have lasted for weeks or perhaps months. At around the same time, lava erupted from Kilauea's East Rift Zone and probably drained magma from the summit storage. The earliest descriptions of Kilauea (30 years after the Keanakakoi eruption) emphasize the great depth of the floor (300-500 m below the rim) and the presence of stepped ledges. It is therefore likely that the Keanakakoi explosions were deepseated within Kilauea, and that the vent rim was substantially lower than the caldera rim. The change from phreatomagmatic to phreatic phases may reflect the

  15. What is the role of pyroclastic density currents in volcanic ash aggregation? Perspectives from a phreatoplinian eruption deposit, New Zealand

    NASA Astrophysics Data System (ADS)

    Van Eaton, A. R.; Wilson, C. J.

    2012-12-01

    This study documents the processes and products of volcanic ash aggregation within individual phases of the 25.4 ka Oruanui super-eruption from Taupo volcano, New Zealand. Textural and stratigraphic relationships of aggregates are examined in seven of the ten erupted units, which range from relatively dry styles of eruption and deposition (fall units 2, 5) to mixed (units 6, 7, 8) and dominantly wet (unit 3). Aggregate structures and grain size distributions shift abruptly over vertical scales of cm to dm within and between eruptive units, providing diagnostic features that identify deposits emplaced as vertical fallout or pyroclastic density currents (PDCs). The six categories of ash aggregates documented here are used to infer distinct volcanic and meteorological interactions in the eruption cloud related to dispersal characteristics and mode of emplacement. Our field observations support the notion that deposits bearing matrix-supported accretionary lapilli with complex internal layering and abundant rim fragments are associated with emplacement of PDCs. However, on the basis of grain size distributions and field relationships, it is inferred that these types of ash aggregates formed their ultrafine (<10 μm ash) outer layers in the overriding fine ash cloud elutriated from PDCs, not during transport within the basal portion of ground-hugging currents. The propagation of voluminous PDCs beneath an overriding buoyant plume - whether coignimbrite or vent-derived in origin - is proposed to generate the observed, concentrically layered accretionary lapilli by producing wedge-like updrafts of convectively unstable, ash-laden air. The apparent coarsening of mean grain size with distance from source, which is observed in the aggregate-bearing fall deposits, reflects a combination of multi-level plume transport and preferential scavenging of fine ash <250 μm. Proximal fallout and melting of ice in the clouds was likely to have contributed a key source of liquid water

  16. The nature, origins and distribution of ash aggregates in a large-scale wet eruption deposit: Oruanui, New Zealand

    NASA Astrophysics Data System (ADS)

    Van Eaton, Alexa R.; Wilson, Colin J. N.

    2013-01-01

    This study documents the processes and products of volcanic ash aggregation in phreatomagmatic phases of the 25.4 ka Oruanui supereruption from Taupo volcano, New Zealand. Detailed textural and stratigraphic relationships of aggregates are examined in six of the ten erupted units, which range from relatively dry styles of eruption and deposition (units 2, 5) to mixed (units 6, 7, 8) and dominantly wet (unit 3). Aggregate structures and grain size distributions shift abruptly over vertical scales of cm to dm, providing diagnostic features to identify deposits emplaced primarily as vertical fallout or pyroclastic density currents (PDCs). The six categories of ash aggregates documented here are used to infer distinct volcanic and meteorological interactions in the eruption cloud related to dispersal characteristics and mode of emplacement. Our field observations support the notion of Brown et al. (2010, Origin of accretionary lapilli within ground-hugging density currents: evidence from pyroclastic couplets on Tenerife. Geol. Soc. Am. Bull. 122, 305-320) that deposits bearing matrix-supported accretionary lapilli with concentric internal structure and abundant rim fragments are associated with emplacement of PDCs. However, on the basis of grain size distributions and field relationships, it is inferred that these types of ash aggregates formed their ultrafine ash (dominantly < 10 μm) outer layers in the buoyant plumes of fine ash lofted from PDCs, rather than during lateral transport in ground-hugging density currents. The propagation of voluminous PDCs beneath an overriding buoyant cloud - whether coignimbrite or vent-derived in origin - is proposed to generate the observed, concentrically structured accretionary lapilli by producing multiple updrafts of convectively unstable, ash-laden air. The apparent coarsening of mean grain size with distance from source, which is observed in aggregate-bearing fall facies, reflects a combination of multi-level plume transport

  17. Volcanic particle aggregation in explosive eruption columns. Part I: Parameterization of the microphysics of hydrometeors and ash

    NASA Astrophysics Data System (ADS)

    Textor, C.; Graf, H. F.; Herzog, M.; Oberhuber, J. M.; Rose, William I.; Ernst, G. G. J.

    2006-02-01

    The aggregation of volcanic ash particles within the eruption column of explosive eruptions has been observed at many volcanoes. It influences the residence time of ash in the atmosphere and the radiative properties of the umbrella cloud. However, the information on the processes leading to aggregate formation are still either lacking or very incomplete. We examine the fate of ash particles through numerical experiments with the plume model ATHAM (Active Tracer High resolution Atmospheric Model) in order to determine the conditions that promote ash particle aggregation. In this paper we describe the microphysics and parameterization of ash and hydrometeors. In a companion paper (this issue) we use this information in a series of numerical experiments. The parameterization includes the condensation of water vapor in the rising eruption column. The formation of liquid and solid hydrometeors and the effect of latent heat release on the eruption column dynamics are considered. The interactions of hydrometeors and volcanic ash within the eruption column that lead to aggregate formation are simulated for the first time within a rising eruption column. The microphysical parameterization follows a modal approach. The hydrometeors are described by two size classes, each of which is divided into a liquid and a frozen category. By analogy with the hydrometeor classification, we specify four categories of volcanic ash particles. We imply that volcanic particles are active as condensation nuclei for water and ice formation. Ash can be contained in all categories of hydrometeors, thus forming mixed particles of any composition reaching from mud rain to accretionary lapilli. Collisions are caused by gravitational capture of particles with different fall velocity. Coalescence of hydrometeor-ash aggregates is assumed to be a function of the hydrometeor mass fraction within the mixed particles. The parameterization also includes simplified descriptions of electrostatics and salinity

  18. Columbia River Basalt Chemistry, Degassing, and Eruption Dynamics: Insights From Quenched Glassy Lapilli and Tuffs

    NASA Astrophysics Data System (ADS)

    Davis, K.; Wolff, J.; Rowe, M. C.; Neill, O. K.

    2015-12-01

    Primary eruptive vent areas for several lavas in the Imnaha and Grande Ronde Formations of the Columbia River Basalt exhibit phreatomagmatic character, due to the interaction of rising flood basalt magma with groundwater and/or surface water. Vent constructional forms range from extensive (>1 km) maar complexes with abundant basement lithics to small (<<1 km), lithic-poor low-angle cones. Phreatomagmatic tephra is lithified and variably palagonitized, but glassy basaltic lapilli can be recovered from many locations. Many lapilli have experienced variable degrees of Na leaching but preserve magmatic abundances of most other elements; nonetheless in many cases pristine, unmodified glass is amenable to analysis. In addition, phenocrysts in lapilli have fully glassy melt inclusions. Glassy lapilli have highly variable S contents between ~100 and ~1300 ppm. This is consistent with quenching before degassing was complete, a common feature of phreatomagmatic eruptions. Melt inclusions have ≤2900 ppm S, ≤3400 ppm CO2 and ≤2.6 wt% H2O, allowing estimates of atmospheric input from the main phase of Columbia River volcanism. In addition, the lithophile trace element contents, and petrogenetically significant ratios such as Ba/Nb, of glassy lapilli exhibit differ from those in the equivalent 'stony' lava flows by up to a factor of 2. This suggests that processes in the flow and crystallization of lava serve to modify trace element abundances, and may place limits on the petrogenetic significance of trace element data from crystalline lava samples.

  19. Accretionary orogens through Earth history

    USGS Publications Warehouse

    Cawood, Peter A.; Kroner, A.; Collins, W.J.; Kusky, T.M.; Mooney, W.D.; Windley, B.F.

    2009-01-01

    Accretionary orogens form at intraoceanic and continental margin convergent plate boundaries. They include the supra-subduction zone forearc, magmatic arc and back-arc components. Accretionary orogens can be grouped into retreating and advancing types, based on their kinematic framework and resulting geological character. Retreating orogens (e.g. modern western Pacific) are undergoing long-term extension in response to the site of subduction of the lower plate retreating with respect to the overriding plate and are characterized by back-arc basins. Advancing orogens (e.g. Andes) develop in an environment in which the overriding plate is advancing towards the downgoing plate, resulting in the development of foreland fold and thrust belts and crustal thickening. Cratonization of accretionary orogens occurs during continuing plate convergence and requires transient coupling across the plate boundary with strain concentrated in zones of mechanical and thermal weakening such as the magmatic arc and back-arc region. Potential driving mechanisms for coupling include accretion of buoyant lithosphere (terrane accretion), flat-slab subduction, and rapid absolute upper plate motion overriding the downgoing plate. Accretionary orogens have been active throughout Earth history, extending back until at least 3.2 Ga, and potentially earlier, and provide an important constraint on the initiation of horizontal motion of lithospheric plates on Earth. They have been responsible for major growth of the continental lithosphere through the addition of juvenile magmatic products but are also major sites of consumption and reworking of continental crust through time, through sediment subduction and subduction erosion. It is probable that the rates of crustal growth and destruction are roughly equal, implying that net growth since the Archaean is effectively zero. ?? The Geological Society of London 2009.

  20. Modeling volcanic ash dispersal

    ScienceCinema

    None

    2016-07-12

    Explosive volcanic eruptions inject into the atmosphere large amounts of volcanic material (ash, blocks and lapilli). Blocks and larger lapilli follow ballistic and non-ballistic trajectories and fall rapidly close to the volcano. In contrast, very fine ashes can remain entrapped in the atmosphere for months to years, and may affect the global climate in the case of large eruptions. Particles having sizes between these two end-members remain airborne from hours to days and can cover wide areas downwind. Such volcanic fallout entails a serious threat to aircraft safety and can create many undesirable effects to the communities located around the volcano. The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard scenarios and/or to give short-term forecasts during emergency situations. This talk will be focused on the main aspects related to modeling volcanic ash dispersal and fallout with application to the well known problem created by the Eyjafjöll volcano in Iceland. Moreover, a short description of the main volcanic monitoring techniques is presented.

  1. Modeling volcanic ash dispersal

    SciTech Connect

    2010-10-22

    Explosive volcanic eruptions inject into the atmosphere large amounts of volcanic material (ash, blocks and lapilli). Blocks and larger lapilli follow ballistic and non-ballistic trajectories and fall rapidly close to the volcano. In contrast, very fine ashes can remain entrapped in the atmosphere for months to years, and may affect the global climate in the case of large eruptions. Particles having sizes between these two end-members remain airborne from hours to days and can cover wide areas downwind. Such volcanic fallout entails a serious threat to aircraft safety and can create many undesirable effects to the communities located around the volcano. The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard scenarios and/or to give short-term forecasts during emergency situations. This talk will be focused on the main aspects related to modeling volcanic ash dispersal and fallout with application to the well known problem created by the Eyjafjöll volcano in Iceland. Moreover, a short description of the main volcanic monitoring techniques is presented.

  2. Degassing at Anatahan volcano during the May 2003 eruption: Implications from petrology, ash leachates, and SO 2 emissions

    NASA Astrophysics Data System (ADS)

    de Moor, J. M.; Fischer, T. P.; Hilton, D. R.; Hauri, E.; Jaffe, L. A.; Camacho, J. T.

    2005-08-01

    On 10 May 2003, Anatahan volcano (located at 16°21' N 145°40' E on the Mariana arc) entered its first historical eruptive episode, sending ash to > 12 km into the atmosphere. Abundant accretionary lapilli, quenched pumice textures, and hydrothermal minerals in the earliest eruptive deposits indicate hydromagmatic interaction and active mining of the pre-eruptive hydrothermal system. Whole-rock compositions of the products erupted within the first week are chemically homogenous, with SiO 2 ˜61%, MgO ˜2.1%, K 2O ˜1.4%, Na 2O ˜4.1% and Fe 2O 3 ˜9.1%. The products are classified as medium-K andesites with tholeiitic affinity. Slightly more silicic matrix glass compositions (up to 63% SiO 2 in microlite-rich matrices) overlap with whole rock, suggesting limited crystal fractionation with microlite crystallization responsible for the more evolved residual melt. Decreasing corrected LOI values (2.3-1.4 wt.%) upsection are consistent with waning hydrothermal mineral contributions as the eruption progressed. Oxygen fugacity calculations based on the ferric to ferrous iron ratio of bulk samples indicate an oxidized magma with ΔNNO ˜+1. Two-pyroxene equilibrium thermometry suggests magmatic temperatures of 1050-1100 °C. Matrix glass volatile contents show a degassed residual melt, with < 0.5 wt.% H 2O, 1000-2000 ppm Cl, 480-780 ppm F, 50-150 ppm S, and < 5 ppm CO 2. A magmatic SO 2 flux of 3-4.5 kt/day was measured by COSPEC on 21 May. Ash leachate data indicate a decreasing S/Cl ratio (3.3-0.7) in the eruptive plume between 10 and 21 May, with a relatively constant Cl concentration. Assuming a constant Cl flux, an SO 2 flux of 14-22 kt/day is calculated for 10 May. The average S concentration from ash leachates (1230 mg/kg) suggests that at least 25% of the SO 2 (˜60 kt) erupted from Anatahan between 10 and 21 May was removed from the plume by the precipitation of sulphate salts in the eruption column, adsorbtion onto ash particles and subsequent deposition. Molar

  3. Unusual lapilli tuff ejecta erupted at Stromboli during the 15 March 2007 explosion shed light on the nature and thermal state of rocks forming the crater system of the volcano

    NASA Astrophysics Data System (ADS)

    Del Moro, Stefano; Renzulli, Alberto; Landi, Patrizia; La Felice, Sonia; Rosi, Mauro

    2013-03-01

    Textural and mineralogical study of high-temperature, angular blocks erupted during the Stromboli explosion of 15 March 2007 was used to make inferences on the nature and thermal state of rocks forming the subsurface of the volcano' summit crater terrace. The studied ejecta consist of lapilli tuff that formed as a result of the transformation and high temperature induration (sintering) of the basaltic scoriae, lapilli and ash originally accumulated as loose tephra during the current activity of the volcano. The main processes leading to the tephra transformation were investigated through microstructural observations, mineral and glass analyses (SEM-EDS and EMP analyses). Investigations revealed that subsolidus reactions and partial melting of the tephra occurred, at temperatures higher than 600 °C and under variable fO2 conditions from QFM to HM buffering curves. In some blocks, evidence of high-T reheating and partial melting at the expense of secondary hydrothermal minerals was also observed. In order to track the subsolidus reheating history of the basaltic pyroclasts, a detailed study of the pseudomorphic phases and reactions after olivine, driven by iron oxidation under high-T conditions, was performed. The observed mineralogical transformation suggests that the lapilli tuff material, originating from the burial of tephra routinely accumulated by persistent Strombolian explosions within the crater terrace, were in some cases altered by the circulation of acidic fluids and were in any case reheated due to isotherm rise forced by high heat flux and gas streaming delivered by the underlying magma system. It is worth noting that the ejection of these unusual volcanic lithotypes was possible because a few days before the 15 March 2007 event, the craters were clogged with lapilli tuff material that slid into the crater bottom between 7 and 9 March. Findings of this study suggest that the scattered permanently active vents and shallow conduits of Stromboli are

  4. Hydrogeochemistry of the northern Barbados accretionary complex transect: Ocean Drilling Project leg 110

    SciTech Connect

    Gieskes, J.M. ); Vrolijk, P. ); Blanc, G. )

    1990-06-10

    Detailed studies of the major element geochemistry, oxygen and hydrogen isotope ratios of pore fluids, and the {sup 87}Sr/{sup 86}Sr ratio of dissolved strontium have made it possible to unravel physical and chemical processes that affect the pore fluid chemistry in a transect of drill holes across the northern Barbados accretionary complex. These processes include (1) alteration of volcanic ash buried in the Pleisticene-Pliocene sediment column; (2) alteration of underlying basalts of layer 2 of the oceanic crust; (3) movement of fluids from deep in the accretionary complex along fault zones (particularly the decollement) and minor permeable layers; these fluids from deeper in the complex are characterized by low chloride concentrations and increased {sup {delta}18}O(H{sub 2}O) values, presumably as a result of dehydration of smectite interlayers; and (4) mixing processes involving the migrating fluids cause incongruities in the geochemical anomalies of these fluids.

  5. Quantify ash aggregation associated to the 26 April 1979 Saint Vincent de la Soufrière eruption

    NASA Astrophysics Data System (ADS)

    Poret, Matthieu; Costa, Antonio; Folch, Arnau

    2016-04-01

    The 26 April 1979 an eruption occurred at Saint Vincent de la Soufrière volcano, West Indies, generating an extended tephra fallout deposit from the slope of the volcano toward the South of the island. This event was observed and studied by Brazier et al. (1982). This study provided a few tens of field observations that allowed an estimation of the tephra loading map and other observations on volcanological parameters such as eruptive column height, duration and erupted volume. They also provided information related to aggregation that was significant during the eruption. Here, the field observations and the meteorological fields are used in order to reconstruct the tephra dispersal by using the Fall3D model. The main goal is to better quantify the total mass of fine ash that aggregated during the eruption providing important information and constraints on aggregation processes. The preliminary results show that field observations are well captured using the simplified aggregation parameterization proposed by Cornell et al. (1983) whereas accretionary lapilli can be described adding a second aggregate class (with a diameter of 2 mm, a density of 2000 kg/m3 and a sphericity of 1) representing only a few percentage of the total amount of tephra. Such percentage was estimated by an empirical approach best fitting field observation. The simulation that best fit the field observations gives an estimation of the column height of about 12.5 km above the vent, a mass eruption rate of 6.0d+6 kg/s and a total mass of 2.2d+9 kg erupted. To go further we will use these results within the 1-D cross-section averaged eruption column model named FPLUME-1.0 based on the Buoyant Plume Theory (BPT) that considers aggregation processes within the plume.

  6. Structure and Stratigraphy of the Barbados Accretionary Prism and the Tobago Forearc Basin

    NASA Astrophysics Data System (ADS)

    Chaderton, N. A.; Wood, L. J.; Mann, P.

    2004-12-01

    The relationship between the Lesser Antilles island arc, the Tobago forearc basin, and the Barbados accretionary prism shows classic convergent margin geometry. Barbados is the only emergent part of the accretionary prism with 80% of the island's land area being covered by Pleistocene limestone. Erosion of the limestone cap in the northeastern part of the island exposes older rocks of the prism. A 450-km2 2-D seismic data volume allows extension of these stratigraphic units offshore and definition of a regional structural framework. The relationship between the unit identified onshore as the Early Eocene to Middle Miocene Oceanic Formation and the basal unit, the intensively folded and faulted Eocene prism rocks of the Scotland Group, has long been debated. Previous proposals claim that the Oceanic Formation, consisting of pelagic clays with some ash beds, is allochthonous and has been thrusted into its present position above accreted sediments of the Scotland Group. However, seismic data show no evidence of nappes-the basis for the overthrusting hypothesis. Seismic interpretation presented here supports the opposing view that the Oceanic Formation and its offshore equivalent in the offshore Tobago forearc basin was deposited in situ and onlap the older, more highly deformed rocks of the accretionary prism. Previous workers proposed that the region's extensive mud diapirism (identified onshore as the Joes River Formation) has caused the emergence of Barbados, which continues to rise 0.44 mm/yr. However, seismic lines suggest that the island's emergence and present-day uplift is related to footwall uplift along a large, NE-striking normal fault off the east coast of the island.

  7. Pyroclastic Eruptions in a Mars Climate Model: The Effects of Grain Size, Plume Height, Density, Geographical Location, and Season on Ash Distribution

    NASA Astrophysics Data System (ADS)

    Kerber, L. A.; Head, J. W.; Madeleine, J.; Wilson, L.; Forget, F.

    2010-12-01

    Pyroclastic volcanism has played a major role in the geologic history of the planet Mars. In addition to several highland patera features interpreted to be composed of pyroclastic material, there are a number of vast, fine-grained, friable deposits which may have a volcanic origin. The physical processes involved in the explosive eruption of magma, including the nucleation of bubbles, the fragmentation of magma, the incorporation of atmospheric gases, the formation of a buoyant plume, and the fall-out of individual pyroclasts has been modeled extensively for martian conditions [Wilson, L., J.W. Head (2007), Explosive volcanic eruptions on Mars: Tephra and accretionary lapilli formation, dispersal and recognition in the geologic record, J. Volcanol. Geotherm. Res. 163, 83-97]. We have further developed and expanded this original model in order to take into account differing temperature, pressure, and wind regimes found at different altitudes, at different geographic locations, and during different martian seasons. Using a well-established Mars global circulation model [LMD-GCM, Forget, F., F. Hourdin, R. Fournier, C. Hourdin, O. Talagrand (1999), Improved general circulation models of the martian atmosphere from the surface to above 80 km, J. Geophys. Res. 104, 24,155-24,176] we are able to link the volcanic eruption model of Wilson and Head (2007) to the spatially and temporally dynamic GCM temperature, pressure, and wind profiles to create three-dimensional maps of expected ash deposition on the surface. Here we present results exploring the effects of grain-size distribution, plume height, density of ash, latitude, season, and atmospheric pressure on the areal extent and shape of the resulting ash distribution. Our results show that grain-size distribution and plume height most strongly effect the distance traveled by the pyroclasts from the vent, while latitude and season can have a large effect on the direction in which the pyroclasts travel and the final shape

  8. Lithospheric cooling as a basin forming mechanism within accretionary crust.

    NASA Astrophysics Data System (ADS)

    Holt, P. J.; Allen, M.; van Hunen, J.; Björnseth, H. M.

    2009-04-01

    Widely accepted basin forming mechanisms are limited to flexure of the lithosphere, lithospheric stretching, lithospheric cooling following rifting and, possibly, dynamic topography. In this work forward models have been used to investigate lithospheric growth due to cooling beneath accretionary crust, as a new basin forming mechanism. Accretionary crust is formed from collision of island arcs, accretionary complexes and fragments of reworked older crust at subduction zones, and therefore has thin lithosphere due to melting and increased convection. This is modeled using a 1D infinite half space cooling model similar to lithospheric cooling models for the oceans. The crustal composition and structure used in the models has been varied around average values of accretionary crust to represent the heterogeneity of accretionary crust. The initial mantle lithosphere thickness used in the model was 20 km. The model then allows the lithosphere to thicken as it cools and calculates the subsidence isostatically. The model produces sediment loaded basins of 2-7 km for the various crustal structures over 250 Myrs. Water-loaded tectonic subsidence curves from the forward models were compared to tectonic subsidence curves produced from backstripping wells from the Kufrah and Ghadames basins, located on the accretionary crust of North Africa. A good match between the subsidence curves for the forward model and backstripping is produced when the best estimates for the crustal structure, composition and the present day thickness of the lithosphere for North Africa are used as inputs for the forward model. This shows that lithospheric cooling provides a good method for producing large basins with prolonged subsidence in accretionary crust without the need for initial extension.

  9. Age of the Xalnene Ash, Central Mexico and Archeological Implications

    NASA Astrophysics Data System (ADS)

    Renne, P. R.; Feinberg, J. M.; Waters, M. R.; Cabrales, J. A.; Castillo, P. O.; Campa, M. P.; Knight, K. B.

    2005-12-01

    Human footprints ~40 ka old have been reported from the Toloquilla quarry near Valsequillo Reservoir, ca. 15 km south of the city of Puebla in central Mexico (http://www.mexicanfootprints.co.uk/default.htm). If correct, this would be important evidence for early peopling of the Americas. The indentations interpreted as footprints and other ichnofossils occur on the surface of an indurated basaltic lapilli tuff within a several meter thick sequence of thinly bedded (1-10 cm) tuffs of similar character, lacking paleosols, erosional features or interlayered sediments, informally known as the Xalnene ash. A sample was collected at 18°55.402` N latitude and 098°09.375` W longitude from the surface on which the purported footprints occur. Lapilli were separated and analyzed by incremental heating 40Ar/39Ar methods, yielding 9 indistinguishable plateau ages averaging 1.30 ±0.03 Ma (2σ) for single lapilli (N=6) and multiple lapilli (N=3) subsamples. Though some minor discordance (presumably due to 39Ar recoil) is manifest in 5 of the age spectra, all plateaux comprise >60% of the 39Ar released and 4 or more consecutive steps. Paleomagnetic data from azimuthally unoriented bulk samples of 11.25 cm3 reveal a reverse polarity (I = -32.1°) thermoremanent component carried by titanomagnetite and a normal polarity component carried by goethite. Measurements on individual matrix-free lapilli lack the goethite component, which is presumed to be associated with the clay-rich cement. Consistency of the reverse component implies deposition of the lapilli at supra-Curie temperatures, with no postdepositional reworking. Reverse polarity is consistent with deposition during chron C1r.2r (1.77 to 1.07 Ma) as indicated by the 40Ar/39Ar data. If the features observed on the tuff are indeed footprints, their 1.3 Ma antiquity would be truly remarkable, predating by far any other evidence for human presence in the Americas and in fact predating the evolutionary emergence of Homo sapiens

  10. Thermochronology of the Torlesse accretionary complex, Wellington region, New Zealand

    NASA Astrophysics Data System (ADS)

    Kamp, Peter J. J.

    2000-08-01

    The Torlesse Complex comprises several Mesozoic accretionary prism complexes together forming continental basement over large parts of New Zealand. This study focuses on the thermal history of relatively low grade graywacke rocks exposed in a transect in southern North Island that crosses the structural grain of the Torlesse Complex, including its older and younger parts. Zircon fission track (FT) ages for the Late Triassic Rakaia Terrane, which is the most inboard of the accretionary complexes, are partially annealed, some possibly reset, and may indicate early Cretaceous (134±10 Ma) cooling from maximum temperatures (Tmax), probably related to imbrication of younger complexes of the Pahau Terrane. Numerical modeling of the zircon FT ages and published 40ArA/39Ar muscovite and biotite ages for the Rakaia Terrane suggest Tmax values of 265-310°C and exhumation from depths of 10-12 km. The rocks underlying the Aorangi Range and involving the youngest accretionary complex have experienced much lower Tmax values of ≤210° and ≥110°C, bracketed by reset apatite FT ages and detrital zircon FT ages. The occurrence of a circa 100 Ma component of zircon FT ages in both the weakly and highly indurated rocks beneath the Aorangi Range, as well as in remnants of an overlying Albian accretionary slope basin (Whatarangi Formation), imply multistorey accretion and incorporation of sediment into the youngest prism. This circa 100 Ma zircon FT age component also places a maximum age on the termination of Mesozoic subduction beneath the New Zealand region. The occurrence of reset apatite FT ages across the whole of the Wellington transect indicates that at least 4 km of exhumation occurred during the late Miocene.

  11. Hybrid accretionary/collisional mechanism of Paleozoic Asian continental growth

    NASA Astrophysics Data System (ADS)

    Schulmann, Karel; Lexa, Ondrej; Janousek, Vojtech; Pavla, Stipska; Yingde, Jiang; Alexandra, Guy; Min, Sun

    2016-04-01

    Continental crust is formed above subduction zones by well-known process of "juvenile crust growth". This new crust is in modern Earth assembled into continents by two ways: (i) short-lived collisions of continental blocks with the Eurasian continent along the "Alpine-Himalayan collisional/interior orogens" in the heart of the Pangean continental plates realm; and (ii) long lived lateral accretion of ocean-floor fragments along "circum-Pacific accretionary/peripheral orogens" at the border of the Pacific oceanic plate. This configuration has existed since the late Proterozoic, when the giant accretionary Terra Australis Orogen developed at periphery of an old Palaeo-Pacific ocean together with collisional Caledonian and Variscan orogens. At the same time, the large (ca. 9 millions km2) Central Asian Orogenic Belt (CAOB) developed in the NE part of the Pangea. This orogen reveals features of both peripheral and interior orogens, which implies that the generally accepted "peripheral-accretionary" and "interior- collisional" paradigm is not applicable here. To solve this conundrum a new model of unprecedented Phanerozoic continental growth is proposed. In this model, the CAOB precursor evolved at the interface of old exterior and young interior oceans. Subsequently, the new lithospheric domain was transferred by advancing subduction into the interior of the Pangean mostly continental realm. During this process the oceanic crust was transformed into continental crust and it was only later when this specific lithosphere was incorporated into the Asian continent. If true, this concept represents revolutionary insight into processes of crustal growth explaining the enigma of anchoring hybrid lithosphere inside a continent without its subduction or Tibetan-type thickening.

  12. Accretionary origin for the late Archean Ashuanipi Complex of Canada

    NASA Technical Reports Server (NTRS)

    Percival, J. A.

    1988-01-01

    The Ashuanipi complex is one of the largest massif granulite terrains of the Canadian Shield. It makes up the eastern end of the 2000 km long, lower-grade, east-west belts of the Archean Superior Province, permitting lithological, age and tectonic correlation. Numerous lithological, geochemical and metamorphic similarities to south Indian granulites suggest common processes and invite comparison of tectonic evolution. The Ashuanipi granulite terrain of the Cannadian Superior Province was studied in detail, and an origin through self-melting of a 55 km thick accretionary wedge seems possible.

  13. Rate of outward growth of the Mediterranean ridge accretionary complex

    NASA Astrophysics Data System (ADS)

    Kastens, Kim A.

    1991-12-01

    The position as a function time of the deformation front on the southwest flank of the Mediterranean Ridge accretionary complex is constrained as follows: (a) the deformation front is now active; (b) the site of core BAN84-05GC was still near the abyssal plain when displaced shallow water benthic foraminifera of inferred African provenance were redeposited within an upper Pliocene age unit; (c) the site of core BAN84-05GC on the outer flank of the Mediterranean Ridge was already within the topographically rugged accretionary complex when a Pliocene debris flow was emplaced; (d) DSDP Site 125 had already been uplifted into a topographically elevated position when lower Pliocene pelagic ooze was deposited; (e) a gypsum-bearing breccia in DSDP Site 125 requires that the site was either on the abyssal plain or within the tectonically active outer perimeter of the accretionary complex during the Messinian salinity crisis; (f) DSDP Site 377 had already been uplifted into a topographically elevated position when middle Miocene age pelagic marl was deposited; (g) DSDP Site 377 was still on or near the abyssal plain when early to lower-middle Miocene age, smectite-bearing turbidites of inferred African provenance were deposited; and (h) the Mediterranean Ridge began to grow by offscraping against a backstop formed by the Alpine nappes of the Hellenic Arc at the time that subduction began (> 33 Ma). Together, these constraints define a range of potential growth curves for the Mediterranean Ridge, with a rate of outward growth of approximately 0.5 to 2 cm/yr. This growth rate is faster than that inferred for most other modern accretionary prisms, both as an absolute value, and as a fraction of the subduction velocity. An unusually thick incoming section and/or an unusually weak (evaporitic) décollement may contribute to the rapid growth rate. The inferred age of accretion does not increase linearly with distance from the deformation front; rather, there is an apparent

  14. What Controls the Sizes and Shapes of Volcanic Ash? Integrating Morphological, Textural and Geochemical Ash Properties to Decipher Eruptive Processes

    NASA Astrophysics Data System (ADS)

    Liu, E. J.; Cashman, K. V.; Rust, A.

    2015-12-01

    Volcanic ash particles encompass a diverse spectrum of shapes as a consequence of differences in the magma properties and the magma ascent and eruption conditions. We show how the quantitative analysis of ash particle shapes can be a valuable tool for deciphering magma fragmentation and transport processes. Importantly, integrating morphological data with ash texture (e.g. bubble and crystal sizes) and dissolved volatile data provides valuable insights into the physical and chemical controls on the resulting ash deposit. To explore the influence of magma-water interaction (MWI) on fine ash generation, we apply this multi-component characterisation to tephra from the 2500BC Hverfjall Fires, Iceland. Here, coeval fissure vents spanned sub-aerial to shallow lacustrine environments. Differences in the size and morphology of pyroclasts thus reflect fragmentation mechanisms under different near-surface conditions. Using shape parameters sensitive to both particle roughness and internal vesicularity, we quantify the relative proportions of dense fragments, bubble shards, and vesicular grains from 2-D SEM images. We show that componentry (and particle morphology) varies as a function of grain size, and that this variation can be related back to the bubble size distribution. Although both magmatic and hydromagmatic deposits exhibit similar component assemblages, they differ in how these assemblages change with grain size. These results highlight the benefits of characterising ash deposits over a wide range of grain sizes, and caution against inferring fragmentation mechanism from a narrow grain size range. Elevated matrix glass S concentrations in hydromagmatic ash (600-1500 ppm) compared to those in magmatic ash and scoria lapilli (200-500 ppm) indicate interrupted vesiculation. In contrast to the subaerial 'dry' deposits, fragmentation during MWI likely occurred over a greater range of depths with quench rates sufficient to prevent post-fragmentation degassing. High

  15. Subsea Gas Emissions from the Barbados Accretionary Complex

    NASA Astrophysics Data System (ADS)

    Barnard, A.; Sager, W. W.; Snow, J. E.; Max, M. D.

    2015-12-01

    We study newly identified gas plumes in the water column from the Barbados Accretionary Complex using multibeam echo soundings from cruise AT21-02. The multibeam data were used to define a region with several ~600 - 900 m tall gas plumes in the water column directly above cratered hummocky regions of the sea floor that have relatively high backscatter, at a water depth of ~1500 m. The natural gas hydrate stability zone reaches a minimum depth of ~600 m in the water column, similar to that of the tallest imaged bubble plumes, implying hydrate shells on the gas bubbles. Maximum tilt of the plume shows current shear in a direction from northwest to southeast (~128°), similar to the transport direction of North Atlantic Deep Water. The source of hydrocarbons, determined from existing geochemical data, suggests the gas source was subjacent marine Cretaceous source rocks. North-south trending faults, craters and mud volcanoes associated with the gas plumes point to the presence of a deep plumbing system and indicate that gas is a driver of mud volcanism. The widespread occurrence of seafloor morphology related to venting indicates that subsea emissions from the Barbados Accretionary Complex are substantial.

  16. Accretionary rims on inclusions in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Macpherson, G. J.; Hashimoto, A.; Grossman, L.

    1985-01-01

    The origin and composition of the rim sequence on the refractory inclusion in the Allende meteorite are studied. The different textures, mineralogy, and mineral-chemistry of the four layers of the rim are described. The layers are composed of: pyroxene, needles, olivine, hedenbergite, and andradite. Tables of the element and chemical compositions of the layers are presented. The data reveals that: (1) the layers are highly porous masses of euhedral crystals with no intergrowth; (2) layers contain highly disequilibrium mineral assemblages; and (3) the thickness of the layers varies with the underlying topography. These results support the theory that rim structures are accretionary aggregates formed from accretion of independently grown particles onto the surface of inclusions. The formation of the grains in the layers and matrix from nebular condensates is studied.

  17. Multifrequency radar imaging of ash plumes: an experiment at Stromboli

    NASA Astrophysics Data System (ADS)

    Donnadieu, Franck; Freret-Lorgeril, Valentin; Delanoë, Julien; Vinson, Jean-Paul; Peyrin, Frédéric; Hervier, Claude; Caudoux, Christophe; Van Baelen, Joël; Latchimy, Thierry

    2016-04-01

    Volcanic ash emissions in the atmosphere are hazardous to aviation while ash fallout affects people and human activities and may cause damage to infrastructures and economic losses. In the framework of the French Government Laboratory of Excellence ClerVolc initiative, an experiment was carried out on Stromboli volcano (Italy), between 28 September and 4 October 2015. The aim was to retrieve various physical properties of the ash plumes, especially the mass loading parameters which are critical for the modelling of ash dispersal. We used a complementary set of cutting edge techniques recording in different bands of the electromagnetic spectrum. The innovative instrument setup consisted in three radars, hyperspectral thermal infrared and dual-band UV cameras, a mini DOAS-Flyspec and a multigas sensor. A drone equipped with differential GPS was flown near the ash plumes with several sensors including SO2, CO2 and particle counter. We mainly focus on radar measurements of over 200 ash plumes and present some preliminary comparisons at three frequencies. The BASTA Doppler radar at 95 GHz, originally designed for atmospheric studies, was deployed at about 2.2 km in slant distance from the eruptive craters. It was configured to observe volumes above one of the active craters with a spatio-temporal resolution of 12.5 m and 1 s. From the same location, a 1.2 GHz volcano Doppler radar (VOLDORAD) was recording the signature of ballistics and small lapilli at 0.15 s in 60 m-deep volumes. In addition, a commercial 24 GHz micro rain Doppler radar (MRR) simultaneously recorded activity from the Rochette station, at 400 to 650 m from the active craters with a sampling rate of 10 s and a resolution of 25 m. The latter was pointing almost perpendicularly to the other radar beams. Reflectivity factors were measured inside the ash plume above the source vent by the BASTA radar (3 mm wavelength) spanning -9 to +21 dBZ. Fallout could sometimes be tracked during several minutes within

  18. The Cimmerian accretionary wedge of Anarak, Central Iran

    NASA Astrophysics Data System (ADS)

    Zanchi, Andrea; Malaspina, Nadia; Zanchetta, Stefano; Berra, Fabrizio; Benciolini, Luca; Bergomi, Maria; Cavallo, Alessandro; Javadi, Hamid Reza; Kouhpeyma, Meyssam

    2015-04-01

    The occurrence in Iran of several ophiolite belts dating between Late Palaeozoic to Triassic poses several questions on the possible existence of various sutures marking the closure of the Palaeotethys ocean between Eurasia and this Gondwana-derived microplate. In this scenario, the Anarak region in Central Iran still represents a conundrum. Contrasting geochronological, paleontological, paleomagnetic data and reported field evidence suggest different origins for the Anarak Metamorphic Complex (AMC). The AMC is either interpreted, as: (1) relict of an accretionary wedge developed at the Eurasia margin during the Palaeotethys subduction as part of the Cimmerian suture zone of NE Iran, displaced to Central Iran by a large counter-clockwise rotation of the central Iranian blocks; (2) autochthonous unit forming a secondary branch of the main suture zone. Our structural, petrographic and geochemical data indicate that the AMC consists of several metamorphic units also including dismembered "ophiolites" which display different tectono-metamorphic evolutions. Three main ductile deformational events can be distinguished in the AMC. The Morghab and Chah Gorbeh complexes preserve a different M1 metamorphism, characterized by blueschist relics in the S1 foliation of the former unit, and greenschist assemblages in the latter. They share a subsequent similar D2 deformational and M2 metamorphic history, showing a prograde metamorphism with syn- to post-deformation growth of blueschist facies mineral assemblages on pre-existing greenschist facies associations. High pressure, low temperature (HP/LT) metamorphism responsible for the growth of sodic amphibole has been recognized also within marble lenses at the contact between the Chah Gorbeh Complex and serpentinites. Evidence of HP/LT metamorphism also occurs in glaucophane-bearing meta-pillow lavas and serpentinites, which contain antigorite and form most of the "ophiolites" within the AMC. Structural relationships show that the

  19. Neoproterozoic and Paleozoic accretionary orogens exposed at different crustal levels

    NASA Astrophysics Data System (ADS)

    Kroener, A.

    2002-12-01

    Accretionary orogens in the upper crust are dominated by trench and forearc deposits, obducted ophiolite fragments, exotic terranes and well defined structural boundaries such as major shear zones. The Neoproterozoic Arabian-Nubian shield (ANS) of western Arabia and NE Africa, the huge terrain of the Neoproterozoic to Palaeozoic Central Asian mobile belt (CAMB) and the present Indonesian Archipelago are prime examples of such orogens. In the ANS and CAMB, field relationships, rock associations, differences in structural style and metamorphic grade, and geochronology have led to the recognition of terrane assemblages that are related to processes of lateral accretion as now observed in the southwest Pacific and lasting for several hundred my. In the ANS, ocean crust and arc formation began about 900 Ma ago, and terrane accretion was completed by ~600 Ma, whereas in the CAMB the oldest oceanic crust formed some 1000 Ma ago, and terrane accretion continued into the late Palaeozoic. Typical rock associations are trench and forearc sediments, island-arc volcanics, calc-alkaline granitoids, dismembered ophiolite suites and gneissic rocks (microcontinents?) constituting exotic terranes and mostly of distinctly older age and more complex tectono-metamorphic history than the surrounding lower grade rocks. Shear zones frequently separate the terranes and in the ANS also constitue seismic discontinuities extending to the lower crust. The middle to lower crustal high grade assemblages of the Neoproterozoic Mozambique belt (MB) of East Africa, Madagascar, southernmost India, Sri Lanka and East Antarctica are considered to be a deep crustal analogue to the upper crustal accretionary belts described above. Typical characteristics are (1) voluminous calc-alkaline granitoid suites, now layered gneisses, and interpreted as root zones of arc terranes, (2) tectonic interdigitation of Archaean to Palaeoproterozoic gneisses with Neoproterozoic rocks, probably brought about during

  20. Generation, migration, and resource potential for hydrocarbons in accretionary subduction systems - a large, unconventional hydrocarbon resource

    SciTech Connect

    Stevenson, A.J. )

    1993-01-01

    Methane and other gaseous and liquid hydrocarbons are common components of accretionary complexes and have been observed in all environments within modern and fossil accretionary accumulations. Methane is generated in this setting by both microbial and thermal processes, but the limited number of samples analyzed prevents an accurate assessment of the relative importance of these two gas generation mechanisms. Large accretionary prisms are geologic settings which, owing to the large amounts of organic detritus cycling through them, represent a large potential source of methane. Organic detritus in accretionary systems is primarily terrestrial in origin and thus gas prone. Variations in the sediment input, thermal structure, fluid flow regime, and structural style of accretionary prisms have a substantial effect on the amount of sediment that enters the gas generation window and on the amount and type of hydrocarbons generated. Factors favorable for maximum evolution of gas include a large, thick accretionary prism, a thick incoming sedimentary section, substantial axial trench sedimentation fed with continental detritus, development of the decollement near the top of the incoming section, substantial underplating, a young subducting plate, and slow to moderate plate convergence rates. On a worldwide basis, long-term methane generation potential is estimated at 1.5x10[sup 10] m[sup 3] (0.5 trillion cubic feet or Tcf) per year in the accretionary subduction setting. No commercial accumulations of gas have yet been identified in this setting; this lack of accumulations implies that much of the gas generated may escape to the oceans and the atmosphere. However, accretionary complexes have not been extensively explored for hydrocarbons, and the trapping of even a small part of the gas generated could result in a substantial commercial resource. 37 refs., 5 figs.

  1. Unraveling the New England orocline, east Gondwana accretionary margin

    NASA Astrophysics Data System (ADS)

    Cawood, P. A.; Pisarevsky, S. A.; Leitch, E. C.

    2011-10-01

    The New England orocline lies within the Eastern Australian segment of the Terra Australis accretionary orogen and developed during the late Paleozoic to early Mesozoic Gondwanide Orogeny (310-230 Ma) that extended along the Pacific margin of the Gondwana supercontinent. The orocline deformed a pre-Permian arc assemblage consisting of a western magmatic arc, an adjoining forearc basin and an eastern subduction complex. The orocline is doubly vergent with the southern and northern segments displaying counter-clockwise and clockwise rotation, respectively, and this has led to contrasting models of formation. We resolve these conflicting models with one that involves buckling of the arc system about a vertical axis during progressive northward translation of the southern segment of the arc system against the northern segment, which is pinned relative to cratonic Gondwana. Paleomagnetic data are consistent with this model and show that an alternative model involving southward motion of the northern segment relative to the southern segment and cratonic Gondwana is not permissible. The timing of the final stage of orocline formation (˜270-265 Ma) overlaps with a major gap in magmatic activity along this segment of the Gondwana margin, suggesting that northward motion and orocline formation were driven by a change from orthogonal to oblique convergence and coupling between the Gondwana and Pacific plates.

  2. Linking magmatism with collision in an accretionary orogen

    NASA Astrophysics Data System (ADS)

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A.; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-05-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251–245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen.

  3. Linking magmatism with collision in an accretionary orogen.

    PubMed

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-01-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251-245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen. PMID:27167207

  4. Linking magmatism with collision in an accretionary orogen

    PubMed Central

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A.; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-01-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251–245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen. PMID:27167207

  5. Plutons and accretionary episodes of the Klamath Mountains, California and Oregon

    USGS Publications Warehouse

    Irwin, William P.; Wooden, Joseph L.

    1999-01-01

    The Klamath Mountains consist of various accreted terranes and include many plutons that range in composition from gabbro to granodiorite. Some of the plutons (preaccretionary plutons) were parts of terranes before the terranes accreted; others (accretionary plutons) intruded during or after the accretion of their host terrane(s). This report attempts to (1) graphically illustrate how the Klamath Mountains grew by the accretion of allochthonous oceanic terranes during early Paleozoic to Cretaceous times, (2) identify the plutons as either preaccretionary or accretionary, and (3) genetically relate the plutonic intrusions to specific accretionary episodes. The eight accretionary episodes portrayed in this report are similar to those shown by Irwin and Mankinen (1998) who briefly described the basis for the timing of the episodes and who illustrated the ~110 degrees of clockwise rotation of the Klamath Mountains since Early Devonian time. Each episode is named for the accreting terrane. In all episodes (Figs. 1-8), the heavy black line represents a fault that separates the accreting oceanic rocks on the left from earlier accreted terranes on the right. The preaccretionary plutons are shown within the accreting oceanic crustal rocks to the left of the heavy black line, and the accretionary plutons in most instances are shown intruding previously accreted terranes to the right. Episodes earlier than the Central Metamorphic episode (Fig. 1), and that may have been important in the formation of the early Paleozoic nucleous of the province (the Eastern Klamath terrane), are not known. The 'Present Time' distribution of the accreted terranes and plutons is shown at a large scale in Figure 9. The schematic vertical section (Fig. 10) depicts the terranes as a stack of horizontal slabs that include or are intruded by vertical plutons. Note that at their base the ~170 Ma preaccretionary plutons of the Western Hayfork subterrane are truncated by the ~164 Ma Salt Creek

  6. Structural development of the western Makran Accretionary Complex, Offshore Iran

    NASA Astrophysics Data System (ADS)

    Burberry, C. M.; Jackson, C. A.

    2013-12-01

    The Makran Accretionary Complex (MAC), which straddles the southern offshore regions of Iran and Pakistan, is a fold-thrust system bound by the Murray Ridge and Ornach Nal Fault to the east, and the Minab Fault System (MFS) to the west. It is c. 1000 km wide and the frontal c. 125 km of the system is submerged beneath the Gulf of Oman. Relatively little is known about this system, despite the fact that constitutes a large portion of the Central Tethyan Orogen and is one of the largest accretionary complexes in the world. We use offshore 2D seismic reflection data to investigate the structural style and evolution of the Iranian segment of the MAC. The MAC is divided into two morphologically distinct domains: (i) a northern domain (Domain 1), which is located landward of a prominant break-in-slope on the seabed and is characterised by a series of normal fault-bound sub-basins that are approximately 50 km wide, and which contain numerous, unconformity-bound seismic units; and (ii) a southern domain (Domain 2), which is located basinward of the prominent seabed slope break, and is characterised by alternating ridges and troughs. Seismic data indicate that these structures are laterally continuous (over 100 km long) north-dipping thrust faults, which are overlain by south-verging, non-cylindrical, fault-propagation folds. Towards the western end of the study area, immediately offshore of the prominent onshore trace of the MFS, there is no single structure that can be reliably interpreted as the offshore extension of the MFS. Instead, a series of oblique-slip faults with thrust and strike-slip components are identified, spanning a zone that is c. 40 km wide. In the north and close to the coastline, the faults are dominantly strike-slip, whereas further south, closer to the deformation front, the thrust-sense component is more important. Irrespective of their slip sense, faults in this zone have a similar N-S strike to the onshore trace of the MFS. In addition, the basin

  7. Relationship between carbonate deposits and fluid venting: Oregon Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Kulm, Laverne D.; Suess, Erwin

    1990-06-01

    Active fluid venting and its surface manifestations (unique animals and carbonates) occur over the accretionary prism in the Cascadia subduction zone located off central Oregon. A large variety of authigenic carbonate deposits and unique carbonate structures have been observed from submersibles and remotely operated vehicles and recovered with aid of submersibles and bottom trawls from the outermost continental shelf and lower continental slope. The carbonate deposits range from relatively thin crusts and slabs to irregular edifices and well-formed circular chimneys that rise from 1 to 2 m above the seafloor. Mineralogically, the carbonate cement consists of aragonite, calcite, Mg-calcite, or dolomite with varying amounts of detrital constituents. Stable carbon and oxygen isotope data identify four distinct subgroups of methane-derived carbonates from several different vent sites and different fluid source zones. Subgroup I represents one vent site on the lower slope and is characterized by oxygen isotope values ranging from +6.8‰ to +4.7‰ PDB. Subgroup II represents another vent site about 1 km away and exhibits oxygen values of +3.4‰ to +4.9‰ PDB. Carbon isotopic values range from -40.96 to -30.23‰ versus -44.26 to -53.44‰ PDB, respectively, for the two vents. An irregular edifice from the outer shelf has the same isotopic composition as subgroup II. A companion study shows that the expelled fluids contain largely biogenic methane and methane-derived dissolved carbonate; a shallow fluid source zone (<1 km) is indicated. The isotopic carbon values of the subgroup I and II carbonates are consistent with the carbon composition of the expelled fluids and apparently represent a historical record of the composition of these fluids. In subgroup III, strong 18O enrichment and heavier carbon values characterize the dolomitic chimneys from the outer continental shelf. Cemented sandstones from a "window" in the accretionary complex of the lower slope (subgroup

  8. Landward thrusting in accretionary wedges: evidence for seafloor rupture?

    NASA Astrophysics Data System (ADS)

    Cubas, N.; Souloumiac, P.

    2015-12-01

    The 2004 Sumatra and 2011 Japan earthquakes took the community by surprise because they ruptured frontal sections of megathrust thought to slip aseismically. Studying the deformation of accretionary prisms can help in characterizing the specific structures associated to frontal propagation and determining the mechanical properties leading to this behavior. Recent observations suggest a correlation between landward faults and frontal propagation of earthquakes along the Sumatra subduction zone. Large sections of landward thrusts are also observed along Cascadia known to have ruptured in 1700 with a M~9 generating a large tsunami. In this study, we propose to investigate if specific frictional properties could lead to a landward sequence of thrusting with the limit analysis approach. We first show that such sequence requires very low effective friction along the megathrust with a rather high internal effective friction. We also show that landward sequence appears close to the extensional critical limit. We retrieve the megathrust effective friction for three wedges with different sediment incomes. For Cascadia, we find a maximal effective friction of 0.032. For northern and southern Sumatra, we find μ≤0.02 and μ≤ 0.08 respectively. This very low effective friction is probably due to lithostatic pore pressure. This high pore pressure could either be a long-term property or due to dynamic effects such as thermal pressurization. The fact that landward vergence appears far from the compressional critical limit favors a dynamic effect. Indeed, a wedge would move away from this limit if material is added synchronously to the deformation or if it is suddenly submitted to a lower effective friction. In addition, the long-term high pore pressure could be due to a low permeability enhancing thermal pressurization and co-seismic slip along the frontal part of the megathrust.

  9. Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex.

    PubMed

    Dielforder, Armin; Vollstaedt, Hauke; Vennemann, Torsten; Berger, Alfons; Herwegh, Marco

    2015-01-01

    Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively.

  10. Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex

    PubMed Central

    Dielforder, Armin; Vollstaedt, Hauke; Vennemann, Torsten; Berger, Alfons; Herwegh, Marco

    2015-01-01

    Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. PMID:26105966

  11. Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex.

    PubMed

    Dielforder, Armin; Vollstaedt, Hauke; Vennemann, Torsten; Berger, Alfons; Herwegh, Marco

    2015-01-01

    Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. PMID:26105966

  12. The Eurekan Orogeny: convergent intraplate deformation through accretionary tectonics?

    NASA Astrophysics Data System (ADS)

    Heron, Philip; Pysklywec, Russell; Stephenson, Randell

    2015-04-01

    The Eurekan Orogeny, which created much of the high topography (~1-2km) of Ellesmere Island and adjacent Greenland, exhibits a crustal architecture linked to intraplate orogenesis in the Cenozoic. These features occurred as a result of mountain-building processes the dynamics of which are not well understood. It is generally considered that the rotation of Greenland in the Eocene (related to sedimentary basin formation in Baffin Bay) produced compressional tectonics between Greenland and Ellesmere Island. As part of this process, the Eurekan Orogeny formed away from a traditional convergent ocean-closure plate boundary, and may represent a style of intraplate deformation. One hypothesis is the amalgamation of continental material (i.e., micro-plates) leave deformational `scars' in the crust and mantle lithosphere (specifically in the Ellesmere Island case through accretionary orogenesis in the Palaeozoic). This weakening of the lithosphere may produce episodic reactivation of faults within continental interiors. For example, lithospheric shortening at a time after continental collision could cause the previously deformed crust and mantle lithosphere to produce intraplate deformation. In this work, the geodynamic evolution of the Eurekan Orogeny and its relationship to the tectonics of the Canadian polar margin and northern Baffin Basin is explored using high-resolution thermal-mechanical numerical experiments with the modelling code SOPALE. The modelling of the High Arctic is constrained by the first-order crustal structure of the region (deduced by local gravity field and passive seismological data). Presented are suites of numerical experiments that investigate how the pre-existing lithospheric structures (both crustal and sub-crustal) control the evolution of the resulting intraplate orogen. The influence of other primary modelling parameters, such as crustal thickness and assumed rheology, is also explored. To highlight the role of surface processes on plate

  13. Accretionary complex structure and kinematics during Paleozoic arc continent collision in the southern Urals

    NASA Astrophysics Data System (ADS)

    Alvarez-Marron, J.; Brown, D.; Perez-Estaun, A.; Puchkov, V.; Gorozhanina, Y.

    2000-10-01

    The southern Urals contain a well-preserved accretionary complex that has overthrust the continental margin during arc-continent collision between the East European Craton (EEC) and the Magnitogorsk island arc in the Late Devonian. Within the accretionary complex, we study three tectonic units that differ in deformation style, and each provides a unique geodynamic implication. The Zilair Nappe, the largest and best exposed unit, consists of 5-6 km of syncollisional, arc-derived Upper Devonian to Lower Carboniferous polymictic and graywacke turbidites that were deposited across the continental margin and incorporated by frontal accretion into the accretionary complex. The Zilair Nappe is a bivergent thrust imbricate where the west-vergent thrusts dominate and have associated kilometer-scale ramp anticlines with well developed east-dipping axial planar cleavage. Along its eastern contact, however, the cleavage fans until it dips moderately westward and the folds are east-vergent. Following its emplacement, west-vergent, basement-involved thrusting that breached the whole accretionary complex imbricated the Zilair Nappe. The Timirovo Duplex is structurally beneath the Zilair Nappe, and outcrops for several tens of kilometers along its northwestern margin. The duplex forms a west-vergent thrust stack composed of a highly deformed and sheared Lower and Middle Devonian reef carbonates of the former EEC margin platform. These rocks were shallowly underplated at the base of the accretionary complex during emplacement over the margin. The Suvanyak Complex outcrops along the eastern contact of the Zilair Nappe, and consists of polydeformed greenschist facies metasediments of the former EEC slope that were offscraped, underplated and incorporated at the rear of the accretionary complex.

  14. Asymmetric Ashes

    NASA Astrophysics Data System (ADS)

    2006-11-01

    , it is. "This has some impact on the use of Type Ia supernovae as standard candles," says Ferdinando Patat. "This kind of supernovae is used to measure the rate of acceleration of the expansion of the Universe, assuming these objects behave in a uniform way. But asymmetries can introduce dispersions in the quantities observed." "Our discovery puts strong constraints on any successful models of thermonuclear supernova explosions," adds Wang. Models have suggested that the clumpiness is caused by a slow-burn process, called 'deflagration', and leaves an irregular trail of ashes. The smoothness of the inner regions of the exploding star implies that at a given stage, the deflagration gives way to a more violent process, a 'detonation', which travels at supersonic speeds - so fast that it erases all the asymmetries in the ashes left behind by the slower burning of the first stage, resulting in a smoother, more homogeneous residue.

  15. Activation of fly ash

    DOEpatents

    Corbin, D.R.; Velenyi, L.J.; Pepera, M.A.; Dolhyj, S.R.

    1986-08-19

    Fly ash is activated by heating a screened magnetic fraction of the ash in a steam atmosphere and then reducing, oxidizing and again reducing the hydrothermally treated fraction. The activated fly ash can be used as a carbon monoxide disproportionating catalyst useful in the production of hydrogen and methane.

  16. Activation of fly ash

    DOEpatents

    Corbin, David R.; Velenyi, Louis J.; Pepera, Marc A.; Dolhyj, Serge R.

    1986-01-01

    Fly ash is activated by heating a screened magnetic fraction of the ash in a steam atmosphere and then reducing, oxidizing and again reducing the hydrothermally treated fraction. The activated fly ash can be used as a carbon monoxide disproportionating catalyst useful in the production of hydrogen and methane.

  17. Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Berndt, Christian; Crutchley, Gareth; Chi, Wu-Cheng; Lin, Saulwood; Muff, Sina

    2016-06-01

    Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.

  18. Oceanic, island arc, and back-arc remnants into eastern Kamchatka accretionary complexes

    SciTech Connect

    Fedorchuk, A.V.; Vishnevskaya, V.S.; Izvekov, I.N. )

    1990-06-01

    The Kamchatsky Mts. accretionary complex in the Eastern Kamchatka orogenic belt was studied for identification of the oceanic and suprasubduction components into accretionary wedges. That complex is divided into two tectonic units. The Lower unit is formed sedimentary and tectonic melanges containing arc-related components (Late Senonian volcaniclastics and boninitic gabbro) and oceanic fragments (Fe-Ti-tholeiites, ocean island basalts, and pelagic sediments of Valanginian to Turonian age). The Upper unit consists of ductile deformed oceanic cumulates from troctolites to Fe-Ti-gabbro, 151 to 172 Ma, which are intruded MORB-like diabases with suprasubduction characteristics, 122 to 141 Ma, and are overlain by basalts similar to latter. The Lower and Upper units are separated by a SW-dipping thrust, which is related by an ophiolitoclastic olistostrome of Late Campanian to Early Maestrichtian age. Both units are covered by Paleocene authoclastic deposits. They are all thrusted over the early Neogene island arc complex, 16 to 20 Ma. The Lower unit of the Kamchatsky Mys accretionary complex was originated in a shear zone between a Late Cretaceous island arc and an Early Cretaceous oceanic plate. The Upper unit represents a Jurassic oceanic remnant that formed a basement of Early Cretaceous back-arc or fore-arc basin. Both units were superposed in the latest Cretaceous. The Kamchatsky Mys accretionary complex was emplaced into the Eastern Kamchatka orogenic belt during late Neogene by collision of the early Neogene island arc.

  19. Advanced ash management technologies for CFBC ash.

    PubMed

    Anthony, E J; Berry, E E; Blondin, J; Bulewicz, E M; Burwell, S

    2003-01-01

    The combustion of high-sulphur coal demands the reduction of sulphur emissions. The sorbent most often used in sulphur capture technology is calcium-based. Ashes from technologies such as circulating fluidized bed combustion (CFBC), therefore, contain high calcium levels. The use and disposal of these ashes poses challenges, because of highly exothermic reactions with water, high-pH leachates, and excessive expansion of solidified materials. This paper looks at the potential of two post-combustion ash treatment processes, CERCHAR hydration and AWDS disposal, in solving these challenges. A high-sulphur coal-derived CFBC ash is examined, after CERCHAR hydration treatment, in conjunction with a conventionally hydrated ash, in a range of chemical, geotechnical and utilization scenarios. The ashes are used to make no-cement and roller-compacted concrete as well as Ash Water Dense Suspensions (AWDS). The solidified mortar paste from no-cement concrete is subjected to an extensive geochemical examination to determine how solidification progresses and strength develops, from a chemical point of view. PMID:12909091

  20. Advanced ash management technologies for CFBC ash.

    PubMed

    Anthony, E J; Berry, E E; Blondin, J; Bulewicz, E M; Burwell, S

    2003-01-01

    The combustion of high-sulphur coal demands the reduction of sulphur emissions. The sorbent most often used in sulphur capture technology is calcium-based. Ashes from technologies such as circulating fluidized bed combustion (CFBC), therefore, contain high calcium levels. The use and disposal of these ashes poses challenges, because of highly exothermic reactions with water, high-pH leachates, and excessive expansion of solidified materials. This paper looks at the potential of two post-combustion ash treatment processes, CERCHAR hydration and AWDS disposal, in solving these challenges. A high-sulphur coal-derived CFBC ash is examined, after CERCHAR hydration treatment, in conjunction with a conventionally hydrated ash, in a range of chemical, geotechnical and utilization scenarios. The ashes are used to make no-cement and roller-compacted concrete as well as Ash Water Dense Suspensions (AWDS). The solidified mortar paste from no-cement concrete is subjected to an extensive geochemical examination to determine how solidification progresses and strength develops, from a chemical point of view.

  1. Description and mineralogy of Tertiary volcanic ash partings and their relationship to coal seams, near Homer, Alaska

    SciTech Connect

    Reinink-Smith, L.M.

    1985-04-01

    Outcrops of Tertiary coal-bearing units in sea cliffs of the Kenai Peninsula provide an excellent study area for volcanic ash partings in coals. Twenty mid-to late-Miocene, 50-cm to 3-m thick coal seams exposed in the sea cliffs about 10 km west of Homer contain an average of 10 volcanic ash or lapilli tuff partings each. The bedding relationships of the coal with any one parting cannot be predicted, and the contacts of the partings with the coal range from very sharp to predominantly gradational. These bedding relationships provide clues about the surface on which the ashes fell and on which the coal was accumulating. For example, some ashes fell in standing water, others on irregular subaerial surfaces. The partings are in various stages of alteration to kaolinite and bentonite, and vary in thickness from a few millimeters to about 10 cm. The consistency and texture of the partings depend on the degree of alteration; the less altered partings display visible pumice fragments and euhedral feldspars, commonly within a finer grained matrix. Separate pumice fragments, excluding matrix, can also occur as partings in the coal. The more altered partings may be wet and plastic, or they may be well indurated claystones; the colors range from gray-yellow to dark brown. The indurated prints are more common in older part of the section. The coal seams may be capped by volcanic ash partings and are commonly underlain by a pencil shale of nonvolcanic origin.

  2. Fly ash carbon passivation

    DOEpatents

    La Count, Robert B; Baltrus, John P; Kern, Douglas G

    2013-05-14

    A thermal method to passivate the carbon and/or other components in fly ash significantly decreases adsorption. The passivated carbon remains in the fly ash. Heating the fly ash to about 500 and 800 degrees C. under inert gas conditions sharply decreases the amount of surfactant adsorbed by the fly ash recovered after thermal treatment despite the fact that the carbon content remains in the fly ash. Using oxygen and inert gas mixtures, the present invention shows that a thermal treatment to about 500 degrees C. also sharply decreases the surfactant adsorption of the recovered fly ash even though most of the carbon remains intact. Also, thermal treatment to about 800 degrees C. under these same oxidative conditions shows a sharp decrease in surfactant adsorption of the recovered fly ash due to the fact that the carbon has been removed. This experiment simulates the various "carbon burnout" methods and is not a claim in this method. The present invention provides a thermal method of deactivating high carbon fly ash toward adsorption of AEAs while retaining the fly ash carbon. The fly ash can be used, for example, as a partial Portland cement replacement in air-entrained concrete, in conductive and other concretes, and for other applications.

  3. Very-low-frequency earthquakes indicate a transpressional stress regime in the Nankai accretionary prism

    NASA Astrophysics Data System (ADS)

    Ito, Yoshihiro; Asano, Youichi; Obara, Kazushige

    2009-10-01

    We investigated the stress field within the Nankai accretionary prism of southwestern Japan, where very-low-frequency (VLF) earthquakes occur associated with thrust faulting. A northwest-southeast azimuth of the maximum horizontal principal stress previously estimated from borehole breakouts in wells drilled in the region by deep-sea drilling vessel Chikyu suggests trench-normal shortening, although strike-slip and normal faulting are also possible within a thrust-dominated tectonic environment. We estimated stress orientations and stress ratios by using stress tensor inversion to derive moment tensor solutions for VLF earthquakes in three regions along the Nankai Trough: off Kumano, off Muroto, and Hyuga-nada. The stress orientations we obtained indicate that the regions off Kumano and off Muroto are within a transpressional stress regime with trench-normal shortening, whereas the Hyuga-nada region on the westernmost edge of the Nankai accretionary prism is in a reverse-faulting regime.

  4. Pre-collisional accretionary growth of the southern Laurasian active margin, Central Pontides, Turkey

    NASA Astrophysics Data System (ADS)

    Aygül, Mesut; Okay, Aral I.; Oberhänsli, Roland; Sudo, Masafumi

    2016-03-01

    Cretaceous subduction-accretionary complexes crop out over wide areas in the central part of the Pontides, northern Turkey. To the north, the wedge consists of a low-grade metaflysch sequence with blocks of marble, Na-amphibole-bearing metabasite (PT = 7-12 kbar; 400 ± 70 °C) and serpentinite. 40Ar/39Ar phengite ages from the phyllites of the metaflysch are ca. 100 Ma. The metaflysch sequence is underlain by oceanic crust-derived HP/LT metabasites and micaschists along a major detachment fault. The metabasites are epidote-blueschists consisting of glaucophane, epidote, titanite, and phengite locally with garnet. Fresh lawsonite-blueschists are exposed as blocks along the detachment fault. Peak metamorphic conditions of a garnet-blueschist are constrained to 17 ± 1 kbar and 500 ± 40 °C and of a lawsonite-blueschist to 14 ± 2 kbar and 370-440 °C. 40Ar/39Ar phengite dating on the micaschists constrains the HP/LT metamorphism as 101-92 Ma, younging southward. Middle Jurassic (ca. 160 Ma) accretionary complexes consisting of blueschist to lower greenschist facies metabasites, marble and volcanogenic metasediment intercalations are exposed at the southern part of the Cretaceous wedge. In the studied area, the North Anatolian Fault forms the contact between Cretaceous and Middle Jurassic HP/LT metamorphic rocks. Wide distribution of Cretaceous subduction-accretionary complexes implies accretionary tectonic continental growth along the Laurasian active margin. High amount of clastic sediment flux into the trench has a major effect on enlarging the wedge during the Albian. Tectonic thickening of the oceanic HP/LT metamorphic sequence, however, was possibly achieved by propagation of the décollement along the retreating slab which can create the space necessary for progressive deep level basal underplating and extension of the wedge for subsequent syn-subduction exhumation.

  5. Rotational and accretionary evolution of the Klamath Mountains, California and Oregon, from Devonian to present time

    USGS Publications Warehouse

    Irwin, William P.; Mankinen, Edward A.

    1998-01-01

    The purpose of this report is to show graphically how the Klamath Mountains grew from a relatively small nucleus in Early Devonian time to its present size while rotating clockwise approximately 110°. This growth occurred by the addition of large tectonic slices of oceanic lithosphere, volcanic arcs, and melange during a sequence of accretionary episodes. The Klamath Mountains province consists of eight lithotectonoic units called terranes, some of which are divided into subterranes. The Eastern Klamath terrane, which was the early Paleozoic nucleus of the province, is divided into the Yreka, Trinity, and Redding subterranes. Through tectonic plate motion, usually involving subduction, the other terranes joined the early Paleozoic nucleus during seven accretionary episodes ranging in age from Early Devonian to Late Jurassic. The active terrane suture is shown for each episode by a bold black line. Much of the western boundary of the Klamath Mountains is marked by the South Fork and correlative faults along which the Klamath terranes overrode the Coast Range rocks during an eighth accretionary episode, forming the South Fork Mountain Schist in Early Cretaceous time.

  6. Fluid generation and distribution in the highest sediment input accretionary margin, the Makran

    NASA Astrophysics Data System (ADS)

    Smith, Gemma L.; McNeill, Lisa C.; Henstock, Timothy J.; Arraiz, Daniel; Spiess, Volkhard

    2014-10-01

    Fluids in subduction zones can influence seismogenic behaviour and prism morphology. The Eastern Makran subduction zone, offshore Pakistan, has a very thick incoming sediment section of up to 7.5 km, providing a large potential fluid source to the accretionary prism. A hydrate-related bottom simulating reflector (BSR), zones of high amplitude reflectivity, seafloor seep sites and reflective thrust faults are present across the accretionary prism, indicating the presence of fluids and suggesting active fluid migration. High amplitude free gas zones and seep sites are primarily associated with anticlinal hinge traps, and fluids here appear to be sourced from shallow biogenic sources and migrate to the seafloor along minor normal faults. There are no observed seep sites associated with the surface expression of the wedge thrust faults, potentially due to burial of the surface trace by failure of the steep thrust ridge slopes. Thrust fault reflectivity is restricted to the upper 3 km of sediment and the deeper décollement is non-reflective. We interpret that fluids and overpressure are not common in the deeper stratigraphic section. Thermal modelling of sediments at the deformation front suggests that the deeper sediment section is relatively dewatered and not currently contributing to fluid expulsion in the Makran accretionary prism.

  7. Synchrotron texture analysis of clay-rich sediments from the Nankai trench and accretionary prism

    NASA Astrophysics Data System (ADS)

    Schumann, Kai; Stipp, Michael; Leiss, Bernd; Behrmann, Jan-Hinrich

    2013-04-01

    Synchrotron diffraction is the most suitable tool for fast multi-mineral phase texture analysis of water-containing clay rich sediment samples due to short wavelengths (in the range of 0.12 Å), high energy radiation and a resulting mm- to cm-scale sample penetration. We carried out synchrotron texture analysis on a sample set from the Nankai trench and accretionary prism offshore Japan. Samples were encountered by IODP Expeditions 315, 316 and 333 of the NanTroSEIZE project from a depth range between 25 mbsf (meters below seafloor) and 522 mbsf. The accretionary prism sediments have a relatively uniform composition of approximately 40% clay minerals, 25% quartz, 25% feldspar, and up to 10% calcite. A first sample set analyzed was taken as recovered from drilling; a second sample set was additionally experimentally deformed in a triaxial deformation apparatus up to axial strains of 60%. Measurements were carried out at DESY (German Electron Synchrotron source) in Hamburg. In order to measure complete pole figures sample cylinders of 2 cm in diameter and 2 cm in length were measured in a phi angle-range from -90 to +90° in 5° steps. Rietveld refinement results using the MAUD program package show that the composition of the IODP Expedition 333 samples from the incoming plate differs slightly from the relatively uniform IODP Expedition 315 and 316 samples of the accretionary prism. They contain ~35% clay minerals, ~30% quartz and ~35% feldspar. For IODP Expedition 315 and 316 samples the Rietveld refinement results correspond to the standard XRD data. The synchrotron texture results of the recovered samples without experimental deformation show an increasingly strong preferred orientation of the clay minerals with increasing sediment depth for the incoming plate. Interestingly, also feldspar shows a significant texture, which is likely due to a shape fabric of the grains. The sediment texture can be explained by compaction and porosity reduction with increasing

  8. New insights into the active deformation of accretionary prisms: examples from the Western Makran, Iran

    NASA Astrophysics Data System (ADS)

    Penney, Camilla; Copley, Alex; Oveisi, Benham

    2016-04-01

    The Makran subduction zone, along the southern coasts of Iran and Pakistan, hosts one of the largest exposed accretionary wedges in the world. The western Makran has been characterised by a lack of shallow and thrust seismicity in both the instrumental and historical periods. The Mw 6.1 2013 Minab earthquake thus provides a rare opportunity to study the deformation of the accretionary wedge in the transition region between continent-continent collision, in the Zagros, and oceanic subduction, in the Makran. We study the source parameters and slip distribution of this earthquake using seismology, geodesy and field observations. We observe left-lateral strike-slip motion on a fault striking ENE-WSW; approximately perpendicular to the faults of the Minab-Zendan-Palami fault zone, the main structure previously thought to accommodate the right-lateral shear between the Zagros and the Makran. The fault that ruptured in 2013 is one of a series of approximately E-W striking left-lateral faults visible in the geology and geomorphology. These accommodate a velocity field equivalent to right-lateral shear on N-S striking planes by clockwise rotations about vertical axes. The longitudinal range of shear in the western Makran is likely to be controlled by the distance over which the underthrusting Arabian lithosphere deepens in the transition from continent-continent collision to oceanic subduction. The lack of observed megathrust seismicity in the western Makran has led to assertions that the convergence in this region may be aseismic, in contrast to the eastern Makran, which experienced an Mw8.1 earthquake in 1945. The right-lateral Sistan Suture Zone, which runs ~N-S along the Iran-Afghanistan border to the north of the Makran, appears to separate these regimes. However, right-lateral faulting is not observed south of ~27°N, within the wedge. The Minab earthquake and the 2013 Balochistan earthquake show that the Makran accretionary wedge is dominated by strike-slip faulting

  9. Coal combustion ash haulback

    SciTech Connect

    Gray, R.E.; Gray, T.A.

    1998-12-31

    Coal mining disturbs large tracts of land which must be reclaimed. Unfortunately, iron sulfides which are common in most coals and the adjacent strata weather, forming acid mine drainage (AMD) which degrades surface and ground water. Burning of coal produces combustion by products, most of which are placed in ponds or landfills. Suitable disposal areas are difficult to find and permit, especially in urban areas. This has led to ash haulback--where the waste generated during coal burning is hauled back to a mine for disposal. The potential advantages of coal combustion ash haulback are: Disposal occurs in a disturbed area (mine) rather than disturb additional land near the power plant; The same vehicles used to haul coal from the mine can be used to return the ash to the mine; Ash, if alkaline, may provide neutralization of acidic water or mine overburden commonly found at coal mines; and Low permeability ash could reduce ground water flow through the mine backfill, thus reducing leaching of acid forming constituents or metals. Placement of ash in surface mines provides an efficient, cost-effective method of disposal while at the same time contributing to reclamation of the mine. Wise natural resource management suggests a reasonable approach to disposal of coal ash is to return it to its original location--the mine.

  10. Ash cloud aviation advisories

    SciTech Connect

    Sullivan, T.J.; Ellis, J.S.; Schalk, W.W.; Nasstrom, J.S.

    1992-06-25

    During the recent (12--22 June 1991) Mount Pinatubo volcano eruptions, the US Air Force Global Weather Central (AFGWC) requested assistance of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC) in creating volcanic ash cloud aviation advisories for the region of the Philippine Islands. Through application of its three-dimensional material transport and diffusion models using AFGWC meteorological analysis and forecast wind fields ARAC developed extensive analysis and 12-hourly forecast ash cloud position advisories extending to 48 hours for a period of five days. The advisories consisted of ``relative`` ash cloud concentrations in ten layers (surface-5,000 feet, 5,000--10,000 feet and every 10,000 feet to 90,000 feet). The ash was represented as a log-normal size distribution of 10--200 {mu}m diameter solid particles. Size-dependent ``ashfall`` was simulated over time as the eruption clouds dispersed. Except for an internal experimental attempt to model one of the Mount Redoubt, Alaska, eruptions (12/89), ARAC had no prior experience in modeling volcanic eruption ash hazards. For the cataclysmic eruption of 15--16 June, the complex three-dimensional atmospheric structure of the region produced dramatically divergent ash cloud patterns. The large eruptions (> 7--10 km) produced ash plume clouds with strong westward transport over the South China Sea, Southeast Asia, India and beyond. The low-level eruptions (< 7 km) and quasi-steady-state venting produced a plume which generally dispersed to the north and east throughout the support period. Modeling the sequence of eruptions presented a unique challenge. Although the initial approach proved viable, further refinement is necessary and possible. A distinct need exists to quantify eruptions consistently such that ``relative`` ash concentrations relate to specific aviation hazard categories.

  11. Modeling consolidation and dewatering near the toe of the northern Barbados accretionary complex

    USGS Publications Warehouse

    Stauffer, P.; Bekins, B.A.

    2001-01-01

    At the toe of the northern Barbados accretionary complex, temperature and pore water chemistry data indicate that fluid flow is channeled along the de??collement and other shallow thrust faults. We examine mechanisms that may prevent consolidation and maintain high permeability over large sections of the de??collement. High-resolution bulk density data from five boreholes show that the de??collement is well consolidated at some sites while other sites remain underconsolidated. Underconsolidated de??collement behavior is associated with kilometer-scale negative-polarity seismic reflections from the de??collement plane that have been interpreted to be fluid conduits. We use a coupled fluid flow/consolidation model to simulate the loading response of a 10-km-long by 680-m-thick slice of sediment as it enters the accretionary complex. The simulations capture 185 ka (5 km) of subduction, with a load function representing the estimated effective stress of the overriding accretionary prism (3.8?? taper angle). Simulation results of bulk density in the de??collement 3.2 km arcward of the deformation front are compared with observations. The results show that persistent high pore pressures at the arcward edge of the simulation domain can explain underconsolidated behavior. The scenario is consistent with previous modeling results showing that high pore pressures can propagate intermittently along the de??collement from deeper in the complex. Simulated seaward fluxes in the de??collement (1-14 cm yr-1) lie between previous estimates from modeling studies of steady state (1 m yr-1) flow. Maximum simulated instantaneous fluid sources (2.5??10-13 s-1) are comparable to previous estimates. The simulations show minor swelling of incoming sediments (fluid sources ??? -3 ?? 1015 s-1) up to 3 km before subduction that may help to explain small-scale shearing and normal faulting proximal to the protode??collement. Copyright 2001 by the American Geophysical Union.

  12. Structural signature of sediment accretion in a Palaeozoic accretionary complex, southeastern Australia

    NASA Astrophysics Data System (ADS)

    Miller, John McL.; Gray, David R.

    1996-10-01

    Chaotic block-in-matrix melange, broken formation along high strain zones associated with large scale imbrication, early bedding-parallel cleavage, recumbent folds in turbidites, and structural complexity in cherts are key elements of a mid-Palaeozoic subduction complex in the eastern part of the Lachlan Fold Belt, southeastern Australia. The complex consists of an imbricated turbidite, chert and basalt sequence of mid-Cambrian to Late Ordovician age. Structural and biostratigraphic controls require a complexly imbricated sequence with reversals in younging seawards towards the inferred former trench/subduction zone, as in young subduction accretionary complexes such as the Kodiak accretionary complex in the Aleutians and the Shimanto complex of Japan. Subduction accretion or underplating in the Narooma accretionary complex is not typified by duplexing, but shows a strain-dependent transition from an "inland" belt of chevron-folding cut by reverse faults, to a coastal belt with an early bedding-parallel fabric, isoclinal-recumbent folding, poly-deformation and differentiated layering in quartzrich turbiditic greywackes. Greywacke units show multiple cleavage fabrics formed in one folding event. Cherts below the turbidites show multiple folding events and zones of broken formation with intense veining and stylolitisation. The structurally lowest units, including deformed pillow basalts and block-in-matrix melange, show strong planar-linear fabrics. In the block-in-matrix melange, prolate-shaped pods of greywacke and chert are aligned sub-parallel to the bulk extension direction defined by mica pull-aparts and pressure shadows on pyrite within the mudstone matrix. Mica neocrystallisation and pressure solution are the dominant deformation mechanisms at the base of the complex.

  13. A Three-Dimensional Reflection Seismic Investigation of Seismogenic Zone, in the eastern Nankai accretionary prism

    NASA Astrophysics Data System (ADS)

    Ike, T.; Tokuyama, H.; Ashi, J.; Kuramoto, S.; Matsushima, J.; Yokota, T.; Pascal, G.; Lallemant, S.

    2001-12-01

    We carried out a 3-D reflection seismic survey [SFJ-KAIKO] in the eastern Nankai accretionary prism from June to July 2000. The crustal deformation of the eastern Nankai accretionary prism affected by a nearby collision between the Izu-Bonin arc and the central Japan. Several active fault systems were described by many high-resolution seismic data, and proposed that the Tokai and Kodaiba fault systems were derived from a decollement plane. The main objective of our experiment was to image the plate boundary and identify the up-dip limit of seismogenic zone. The 3-D survey covers 45km long and 5km wide area with 51 seismic lines, located about 50km southwest from Omaezaki. We applied the non-iterative Kirchhoff pre-stack time migration method (Matsushima et.,al 2001) with stacking velocity analysis to our 3-D data. The processed 3-D data gives us a significantly clear image of the thrust faults and the relationship between sediment deformation and thrust activity. A preliminary 3-D interpretation was conducted and leaded the following results.1) The Tokai and Kodaiba thrusts are clearly imaged as out-of-sequence thrusts. 2) Both thrusts are active fault that revealed by the structure of deformed sediments near seafloor. 3) A strong and low frequency reflector can be traced in the entire profile that should be a decollement plane. Tokai and Kodaiba fault systems merged to the decollement plane at same depth. The contact area of the thrust faults and the decollement may be suggesting the up-dip limit of seismogenic zone of the eastern Nankai accretionary prism .The 3-D image will contribute to reveal the mechanism of disastrous earthquakes in the Tokai area.

  14. Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula, southwestern Japan

    NASA Astrophysics Data System (ADS)

    Tsuji, Takeshi; Tokuyama, Hidekazu; Costa Pisani, Patrizia; Moore, Gregory

    2008-11-01

    We developed a theoretical method for predicting effective stress and pore pressure based on rock physics model. We applied the method to reveal the pore pressure distribution within the Nankai accretionary prism off southwestern Japan and to investigate variations in pore pressure associated with evolution of the plate boundary décollement. From the crack aspect ratio spectrum estimated from laboratory and well-log data, we calculated a theoretical relationship between acoustic velocity and mean effective stress by using differential effective medium theory. By iteratively fitting the theoretically calculated velocity to the seismic velocities derived from 3D tomographic inversion, we estimated in situ mean effective stress within the accretionary prism. Pore pressure is then the difference between the effective stress and the confining stress. When we calculated pore pressure, we considered compressive state of stress in the accretionary prism. Our results confirm that pore fluid pressure is high within the subducting sedimentary sequence below the décollement; we determined a normalized pore pressure ratio (λ*) of 0.4-0.7. Abnormal pore pressures develop in the underthrust sequence as a result of the increase in overburden load because of the thickened overlying prism and a low permeability barrier across the décollement. Overpressuring within the accreted sequence is initiated at the deformation front and proceeds landward. The increase in horizontal compaction within the accreted sequence may raise pore pressures within the accreted sequence, and the pore pressure (mean effective stress) contrast at the décollement becomes smaller landward of the deformation front.

  15. Late Cretaceous to early Tertiary transtension and strain partitioning in the Chugach Accretionary Complex, SE Alaska

    USGS Publications Warehouse

    Davis, J.S.; Roeske, S.M.; Karl, S.M.

    1998-01-01

    Shear zones in the Late Cretaceous Sitka Graywacke of the Chugach accretionary complex in southeast Alaska record constrictional finite strains, with maximum principal s tretches plunging shallowly subparallel to strike of the shear zones. Macrostructural analysis indicates the finite strain formed during one deformation event. Microstructural analysis of the shear zones shows that this deformation is ductile, promoted mostly through deformation of low-strength lithic clasts and pressure solution. Kinematic indicators from some of the shear zones indicate dominantly dextral motion. Although multiple scenarios can explain constrictional finite strains in a shear zone, these dextral strike-slip shear zones must have experienced a component of extension across them in order to generate constrictional finite strains. Therefore, the shear zones are dextral transtensional shear zones, an uncommon tectinic regime in an accretionary complex. The transtensional shear zones reflect strike-slip motion related to partitioning of Late Cretaceous to Early Tertiary right-oblique convergence between North America and the Farallon plate. The extensional component that was superposed on the strike-slip shear zones to generate transtension resulted from contemporaneous collapse of the forearc following thickening related to underplating.Shear zones in the Late Cretaceous Sitka Graywacke of the Chugach accretionary complex in southeast Alaska record constrictional finite strains, with maximum principal stretches plunging shallowy sub-parallel to strike of the shear zones. Macrostructural analysis indicates the finite strain formed during one deformation event. Microstructural analysis of the shear zones shows that this deformation is ductile, promoted mostly through deformation of low-strength lithic clasts and pressure solution. Kinematic indicators from some of the shear zones indicate dominantly dextral motion. Although multiple scenarios can explain constrictional finite strains

  16. Thrust fault growth within accretionary wedges: New Insights from 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Orme, H.; Bell, R. E.; Jackson, C. A. L.

    2015-12-01

    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. Previous studies have reported en-echelon thrust fault geometries from the NW part of the dataset, and have related this complex structure to seamount subduction. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. We also demonstrate that the majority of faults grew upward from the décollement, although there is some evidence for downward fault propagation. Our observations

  17. Changes in Explosive Eruptive Styles From Morne Trois Pitons, Dominica, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Tinnin, B.; Smith, A.; Vazquez, J.

    2007-12-01

    The island of Dominica, which is located in the central part of the Lesser Antilles island arc, has witnessed three large-volume Plinian eruptions within the last 100,000 years. One of these eruptions issued from the Morne Trois Pitons caldera and produced the widespread (>62 km2) Layou ignimbrite deposits. The Layou ignimbrite is exposed in two pyroclastic fans that extend NE and NW from the Morne Trois Pitons caldera (now infilled by a Pelean dome complex). Field observations of the NW fan show that the ignimbrite sequence can be subdivided into an unlithified and a lithified faces. The former occurs in distal exposures along the margins of the ignimbrite, whereas the latter is dominant in deposits that occupy central valley-fill locations. In its most distal exposure, the Layou ignimbrite overlies a thick sequence of fluviatile conglomerates. Here the basal unit is an approximately 18 cm thick bed of pumiceous lapilli fall. Lithic clast sizes in this basal unit are consistent with an eruption column height of circa 20-25 km. The basal fall deposit is overlain by 10 cm of ash fall that contains abundant accretionary lapilli (up to 8 mm in diameter), suggesting magma-water interaction and a phreatoplinian style of eruption. SEM imaging of these accretionary lapilli reveal two lapilli types: 1) an aggregate variety comprised entirely of ash (heterogeneous lapilli) and 2) an agglomerated variety composed of ash rimming a core of pumice (homogeneous lapilli). The heterogeneous accretionary lapilli contain concentric stratification of fine and coarse ash laminae suggesting pyroclastic cycling within the moist phreatoplinian column. Overlying these basal fall deposits are at least 3 unlithified pyroclastic flow units with a maximum thickness of over 20 m. Within the Layou Valley west of the caldera the flow units increase in thickness and reach a maximum of 180 m in the upper Layou Valley. The Layou sequence records transitions from plinian fall to phreatoplinian fall

  18. Landward vergence in accretionary prism, evidence for frontal propagation of earthquakes?

    NASA Astrophysics Data System (ADS)

    cubas, Nadaya; Souloumiac, Pauline

    2016-04-01

    Landward vergence in accretionary wedges is rare and have been described at very few places: along the Cascadia subduction zone and more recently along Sumatra where the 2004 Mw 9.1 Sumatra-Andaman event and the 2011 tsunami earthquake occurred. Recent studies have suggested a relation between landward thrust faults and frontal propagation of earthquakes for the Sumatra subduction zone. The Cascadia subduction zone is also known to have produced in 1700 a Mw9 earthquake with a large tsunami across the Pacific. Based on mechanical analysis, we propose to investigate if specific frictional properties could lead to a landward sequence of thrusting. We show that landward thrust requires very low effective friction along the megathrust with a rather high internal effective friction. We also show that landward thrust appears close to the extensional critical limit. Along Cascadia and Sumatra, we show that to get landward vergence, the effective basal friction has to be lower than 0.08. This very low effective friction is most likely due to high pore pressure. This high pore pressure could either be a long-term property or due to dynamic effects such as thermal pressurization. The fact that landward vergence appears far from the compressional critical limit favors a dynamic effect. Landward vergence would then highlight thermal pressurization due to occasional or systematic propagation of earthquakes to the trench. As a consequence, the vergence of thrusts in accretionary prism could be used to improve seismic and tsunamigenic risk assessment.

  19. Accretion in the wake of terrane collision: The Neogene accretionary wedge off Kenai Peninsula, Alaska

    USGS Publications Warehouse

    Fruehn, J.; Von Huene, R.; Fisher, M.A.

    1999-01-01

    Subduction accretion and repeated terrane collision shaped the Alaskan convergent margin. The Yakutat Terrane is currently colliding with the continental margin below the central Gulf of Alaska. During the Neogene the terrane's western part was subducted after which a sediment wedge accreted along the northeast Aleutian Trench. This wedge incorporates sediment eroded from the continental margin and marine sediments carried into the subduction zone on the Pacific plate. Prestack depth migration was performed on six seismic reflection lines to resolve the structure within this accretionary wedge and its backstop. The lateral extent of the structures is constrained by high-resolution swath bathymetry and seismic lines collected along strike. Accretionary structure consists of variably sized thrust slices that were deformed against a backstop during frontal accretion and underplating. Toward the northeast the lower slope steepens, the wedge narrows, and the accreted volume decreases notwith-standing a doubling of sediments thickness in the trench. In the northeasternmost transect, near the area where the terrane's trailing edge subducts, no frontal accretion is observed and the slope is eroded. The structures imaged along the seismic lines discussed here most likely result from progressive evolution from erosion to accretion, as the trailing edge of the Yakutat Terrane is subducting.

  20. Late Cretaceous to Early Tertiary transtension and strain partitioning in the Chugach accretionary complex, SE Alaska

    NASA Astrophysics Data System (ADS)

    Davis, J. Steven; Roeske, Sarah M.; Karl, Sue M.

    1998-05-01

    Shear zones in the Late Cretaceous Sitka Graywacke of the Chugach accretionary complex in southeast Alaska record constrictional finite strains, with maximum principal stretches plunging shallowly subparallel to strike of the shear zones. Macrostructural analysis indicates the finite strain formed during one deformation event. Microstructural analysis of the shear zones shows that this deformation is ductile, promoted mostly through deformation of low-strength lithic clasts and pressure solution. Kinematic indicators from some of the shear zones indicate dominantly dextral motion. Although multiple scenarios can explain constrictional finite strains in a shear zone, these dextral strike-slip shear zones must have experienced a component of extension across them in order to generate constrictional finite strains. Therefore, the shear zones are dextral transtensional shear zones, an uncommon tectonic regime in an accretionary complex. The transtensional shear zones reflect strike-slip motion related to partitioning of Late Cretaceous to Early Tertiary right-oblique convergence between North America and the Farallon plate. The extensional component that was superposed on the strike-slip shear zones to generate transtension resulted from contemporaneous collapse of the forearc following thickening related to underplating.

  1. Microbial methane production in deep aquifer associated with the accretionary prism in Japan.

    PubMed

    Kimura, Hiroyuki; Nashimoto, Hiroaki; Shimizu, Mikio; Hattori, Shohei; Yamada, Keita; Koba, Keisuke; Yoshida, Naohiro; Kato, Kenji

    2010-04-01

    To identify the methanogenic pathways present in a deep aquifer associated with an accretionary prism in Southwest Japan, a series of geochemical and microbiological studies of natural gas and groundwater derived from a deep aquifer were performed. Stable carbon isotopic analysis of methane in the natural gas and dissolved inorganic carbon (mainly bicarbonate) in groundwater suggested that the methane was derived from both thermogenic and biogenic processes. Archaeal 16S rRNA gene analysis revealed the dominance of H(2)-using methanogens in the groundwater. Furthermore, the high potential of methane production by H(2)-using methanogens was shown in enrichments using groundwater amended with H(2) and CO(2). Bacterial 16S rRNA gene analysis showed that fermentative bacteria inhabited the deep aquifer. Anaerobic incubations using groundwater amended with organic substrates and bromoethanesulfonate (a methanogen inhibitor) suggested a high potential of H(2) and CO(2) generation by fermentative bacteria. To confirm whether or not methane is produced by a syntrophic consortium of H(2)-producing fermentative bacteria and H(2)-using methanogens, anaerobic incubations using the groundwater amended with organic substrates were performed. Consequently, H(2) accumulation and rapid methane production were observed in these enrichments incubated at 55 and 65 degrees C. Thus, our results suggested that past and ongoing syntrophic biodegradation of organic compounds by H(2)-producing fermentative bacteria and H(2)-using methanogens, as well as a thermogenic reaction, contributes to the significant methane reserves in the deep aquifer associated with the accretionary prism in Southwest Japan.

  2. Progressive deformation of the Chugach accretionary complex, Alaska, during a paleogene ridge-trench encounter

    NASA Astrophysics Data System (ADS)

    Kusky, Timothy M.; Bradley, Dwight C.; Haeussler, Peter

    1997-02-01

    The Mesozoic accretionary wedge of south-central Alaska is cut by an array of faults including dextral and sinistral strike-slip faults, synthetic and antithetic thrust faults, and synthetic and antithetic normal faults. The three fault sets are characterized by quartz ± calcite ± chlorite ± prehnite slickensides, and are all relatively late, i.e. all truncate ductile fabrics of the host rocks. Cross-cutting relationships suggest that the thrust fault sets predate the late normal and strike-slip fault sets. Together, the normal and strike-slip fault system exhibits orthorhombic symmetry. Thrust faulting shortened the wedge subhorizontally perpendicular to strike, and then normal and strike-slip faulting extended the wedge oblique to orogenic strike. Strongly curved slickenlines on some faults of each set reveal that displacement directions changed over time. On dip-slip faults (thrust and normal), slickenlines tend to become steeper with younger increments of slip, whereas on strike-slip faults, slickenlines become shallower with younger strain increments. These patterns may result from progressive exhumation of the accretionary wedge while the faults were active, with the curvature of the slickenlines tracking the change from a non-Andersonian stress field at depth to a more Andersonian system (σ 1 or σ 2 nearly vertical) at shallower crustal levels. We interpret this complex fault array as a progressive deformation that is one response to Paleocene-Eocene subduction of the Kula-Farallon spreading center beneath the accretionary complex because: (1) on the Kenai Peninsula, ENE-striking dextral faults of this array exhibit mutually cross-cutting relationships with Paleocene-Eocene dikes related to ridge subduction; and (2) mineralized strike-slip and normal faults of the orthorhombic system have yielded 40Ar/ 39Ar ages identical to near-trench intrusives related to ridge subduction. Both features are diachronous along-strike, having formed at circa 65 Ma in

  3. Engineering Model for Ash Formation

    1994-12-02

    Ash deposition is controlled by the impaction and sticking of individual ash particles to heat transfer surfaces. Prediction of deposition therefore requires that the important factors in this process be predictable from coal and operational parameters. Coal combustion, boiler heat transfer, ash formation, ash particle aerodynamic, and ash particle sticking models are all essential steps in this process. The model described herein addresses the prediction of ash particle size and composition distributions based upon combustionmore » conditions and coal parameters. Key features of the model include a mineral redistribution routine to invert CCSEM mineralogical data, and a mineral interaction routine that simulates the conversion of mineral matter into ash during coal burning and yields ash particle size and composition distributions.« less

  4. Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    1998-01-01

    Down-hole geochemical anomalies encountered in active accretionary systems can be used to constrain the timing, rates, and localization of fluid flow. Here we combine a coupled flow and solute transport model with a kinetic model for smectite dehydration to better understand and quantify fluid flow in the Nankai accretionary complex offshore of Japan. Compaction of sediments and clay dehydration provide fluid sources which drive the model flow system. We explicitly include the consolidation rate of underthrust sediments in our calculations to evaluate the impact that variations in this unknown quantity have on pressure and chloride distribution. Sensitivity analysis of steady state pressure solutions constrains bulk and flow conduit permeabilities. Steady state simulations with 30% smectite in the incoming sedimentary sequence result in minimum chloride concentrations at site 808 of 550 mM, but measured chlorinity is as low as 447 mM. We simulate the transient effects of hydrofracture or a strain event by assuming an instantaneous permeability increase of 3-4 orders of magnitude along a flow conduit (in this case the de??collement), using steady state results as initial conditions. Transient results with an increase in de??collement permeability from 10-16 m2 to 10-13 m2 and 20% smectite reproduce the observed chloride profile at site 808 after 80-160 kyr. Modeled chloride concentrations are highly sensitive to the consolidation rate of underthrust sediments, such that rapid compaction of underthrust material leads to increased freshening. Pressures within the de??collement during transient simulations rise rapidly to a significant fraction of lithostatic and remain high for at least 160 kyr, providing a mechanism for maintaining high permeability. Flow rates at the deformation front for transient simulations are in good agreement with direct measurements, but steady state flow rates are 2-3 orders of magnitude smaller than observed. Fluid budget calculations

  5. Regional Variation of CH4 and N2 Production Processes in the Deep Aquifers of an Accretionary Prism.

    PubMed

    Matsushita, Makoto; Ishikawa, Shugo; Nagai, Kazushige; Hirata, Yuichiro; Ozawa, Kunio; Mitsunobu, Satoshi; Kimura, Hiroyuki

    2016-09-29

    Accretionary prisms are mainly composed of ancient marine sediment scraped from the subducting oceanic plate at a convergent plate boundary. Large amounts of anaerobic groundwater and natural gas, mainly methane (CH4) and nitrogen gas (N2), are present in the deep aquifers associated with an accretionary prism; however, the origins of these gases are poorly understood. We herein revealed regional variations in CH4 and N2 production processes in deep aquifers in the accretionary prism in Southwest Japan, known as the Shimanto Belt. Stable carbon isotopic and microbiological analyses suggested that CH4 is produced through the non-biological thermal decomposition of organic matter in the deep aquifers in the coastal area near the convergent plate boundary, whereas a syntrophic consortium of hydrogen (H2)-producing fermentative bacteria and H2-utilizing methanogens contributes to the significant production of CH4 observed in deep aquifers in midland and mountainous areas associated with the accretionary prism. Our results also demonstrated that N2 production through the anaerobic oxidation of organic matter by denitrifying bacteria is particularly prevalent in deep aquifers in mountainous areas in which groundwater is affected by rainfall.

  6. Regional Variation of CH4 and N2 Production Processes in the Deep Aquifers of an Accretionary Prism

    PubMed Central

    Matsushita, Makoto; Ishikawa, Shugo; Nagai, Kazushige; Hirata, Yuichiro; Ozawa, Kunio; Mitsunobu, Satoshi; Kimura, Hiroyuki

    2016-01-01

    Accretionary prisms are mainly composed of ancient marine sediment scraped from the subducting oceanic plate at a convergent plate boundary. Large amounts of anaerobic groundwater and natural gas, mainly methane (CH4) and nitrogen gas (N2), are present in the deep aquifers associated with an accretionary prism; however, the origins of these gases are poorly understood. We herein revealed regional variations in CH4 and N2 production processes in deep aquifers in the accretionary prism in Southwest Japan, known as the Shimanto Belt. Stable carbon isotopic and microbiological analyses suggested that CH4 is produced through the non-biological thermal decomposition of organic matter in the deep aquifers in the coastal area near the convergent plate boundary, whereas a syntrophic consortium of hydrogen (H2)-producing fermentative bacteria and H2-utilizing methanogens contributes to the significant production of CH4 observed in deep aquifers in midland and mountainous areas associated with the accretionary prism. Our results also demonstrated that N2 production through the anaerobic oxidation of organic matter by denitrifying bacteria is particularly prevalent in deep aquifers in mountainous areas in which groundwater is affected by rainfall. PMID:27592518

  7. Regional Variation of CH4 and N2 Production Processes in the Deep Aquifers of an Accretionary Prism.

    PubMed

    Matsushita, Makoto; Ishikawa, Shugo; Nagai, Kazushige; Hirata, Yuichiro; Ozawa, Kunio; Mitsunobu, Satoshi; Kimura, Hiroyuki

    2016-09-29

    Accretionary prisms are mainly composed of ancient marine sediment scraped from the subducting oceanic plate at a convergent plate boundary. Large amounts of anaerobic groundwater and natural gas, mainly methane (CH4) and nitrogen gas (N2), are present in the deep aquifers associated with an accretionary prism; however, the origins of these gases are poorly understood. We herein revealed regional variations in CH4 and N2 production processes in deep aquifers in the accretionary prism in Southwest Japan, known as the Shimanto Belt. Stable carbon isotopic and microbiological analyses suggested that CH4 is produced through the non-biological thermal decomposition of organic matter in the deep aquifers in the coastal area near the convergent plate boundary, whereas a syntrophic consortium of hydrogen (H2)-producing fermentative bacteria and H2-utilizing methanogens contributes to the significant production of CH4 observed in deep aquifers in midland and mountainous areas associated with the accretionary prism. Our results also demonstrated that N2 production through the anaerobic oxidation of organic matter by denitrifying bacteria is particularly prevalent in deep aquifers in mountainous areas in which groundwater is affected by rainfall. PMID:27592518

  8. Early Jurassic Volcanic Rocks from the Raohe Accretionary Complex of NE China: Petrogenesis and Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Wang, Zhihui; Ge, Wenchun

    2016-04-01

    The Raohe accretionary complex is located at the boundary between the Russian Far East and Northeast China, and is an important part of the Western Pacific Ocean tectonic regime. However, owing to the lack of precise age and geochemical constraints, the tectonic setting and petrogenesis of magmatic rocks in this area have been controversial, which has led to the debate on crustal growth mechanisms and subduction accretionary processes in the Northeast China. Herein, we report newly-defined calc-alkaline andesites, dacites, rhyolites, Nb-enriched basaltic-andesites and andesites, and N-MORB type basalts and basaltic-andesites from the Raohe accretionary complex, NE China. All these volcanic rocks are collected from rocks mapped previously as the Late Triassic to Early Jurassic stratums. LA-ICP-MS zircon U-Pb dating for one andesite, one dacites and three rhyolites indicate the occurrence of magmatic events in the Early Jurassic (186-174 Ma). They have positive ɛHf(t) values of +3.4 to +10.6 and relatively high (87Sr/86Sr)i values of 0.704711 to 0.710235. The calc-alkaline andesites, dacites and rhyolites are typical arc magmas, with moderately enriched LILEs and LREEs, distinctly negative HFSEs, consistent with the chemistry of volcanic rocks from an active continental margin setting. The Nb-enriched basaltic-andesites and andesites have higher TiO2, Nb, and Zr contents, higher Nb/Ta (24.03-87.60), Nb/U (11.89-75.94), (Nb/Th)PM (0.67-2.70), and (Nb/La)PM (1.95-5.00) ratios than typical arc basalts. They are relatively enriched in Nb, Zr, Hf and Ti. They have negative ɛNd(t) values of -5.47 to -6.04 and relatively variable (87Sr/86Sr)i values of 0.704648 to 0.711430, suggesting that they were possibly generated by a partial melting of mantle wedge peridotites metasomatized by slab-derived adakitic melts and minor fluids. The N-MORB type basalts and basaltic-andesites have comparatively low TiO2 concentrations (1.18-1.42 wt.%), show almost flat REE patterns with

  9. Mechanics of fold-and-thrust belts and accretionary wedges Cohesive Coulomb theory

    NASA Technical Reports Server (NTRS)

    Dahlen, F. A.; Suppe, J.; Davis, D.

    1984-01-01

    A self-consistent theory for the mechanics of thin-skinned accretionary Coulomb wedges is developed and applied to the active fold-and-thrust belt of western Taiwan. The state of stress everywhere within a critical wedge is determined by solving the static equilibrium equations subject to the appropriate boundary conditions. The influence of wedge cohesion, which gives rise to a concave curvature of the critical topographic surface and affects the orientation of the principal stresses and Coulomb fracture within the wedge, is considered. The shape of the topographic surface and the angles at which thrust faults step up from the basal decollement in the Taiwanese belt is analyzed taking into account the extensive structural and fluid-pressure data available there. It is concluded that the gross geometry and structure of the Taiwan wedge are consistent with normal laboratory frictional and fracture strengths of sedimentary rocks.

  10. ASH and NASH.

    PubMed

    Scaglioni, F; Ciccia, S; Marino, M; Bedogni, G; Bellentani, S

    2011-01-01

    Non-alcoholic steatohepatitis (NASH) and alcoholic steatohepatitis (ASH) have a similar pathogenesis and histopathology but a different etiology and epidemiology. NASH and ASH are advanced stages of non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD). NAFLD is characterized by excessive fat accumulation in the liver (steatosis), without any other evident causes of chronic liver diseases (viral, autoimmune, genetic, etc.), and with an alcohol consumption ≤20-30 g/day. On the contrary, AFLD is defined as the presence of steatosis and alcohol consumption >20-30 g/day. The most common phenotypic manifestations of primary NAFLD/NASH are overweight/obesity, visceral adiposity, type 2 diabetes, hypertriglyceridemia and hypertension. The prevalence of NAFLD in the general population in Western countries is estimated to be 25-30%. The prevalence and incidence of NASH and ASH are not known because of the impossibility of performing liver biopsy in the general population. Up to 90% of alcoholics have fatty liver, and 5-15% of these subjects will develop cirrhosis over 20 years. The risk of cirrhosis increases to 30-40% in those who continue to drink alcohol. About 10-35% of alcoholics exhibit changes on liver biopsy consistent with alcoholic hepatitis. Natural histories of NASH and ASH are not completely defined, even if patients with NASH have a reduced life expectancy due to liver-related death and cardiovascular diseases. The best treatment of AFLD/ASH is to stop drinking, and the most effective first-line therapeutic option for NAFLD/NASH is non-pharmacologic lifestyle interventions through a multidisciplinary approach including weight loss, dietary changes, physical exercise, and cognitive-behavior therapy. PMID:21734385

  11. Mixing of methane and sulphate due to fluid flow in the Barbados accretionary prism

    SciTech Connect

    Laier, T. )

    1996-01-01

    Methane concentrations above background level in sulphate-containing (15 mmol/l) pore waters have been observed in the d6collement zone of the Barbados accretionary prism. The peak in methane concentration in the decollement was found at a number of sites by headspace analysis of cores retrieved during ODP Legs 110 156 at the toe of the accretionary prism. [delta][sup 13]C[sub 1] values between -22[per thousand] and -36[per thousand] indicate that methane oxidation occurs possibly due to sulphate reduction. Thus, the presence of both methane and sulphate at the same depths suggests mixing of fluids due to fluid flow. Fluid flow is also indicated by the distinct minima in chloride concentrations at the same depths. In the case of on-going methane oxidation, mixing of sulphate and methane fluids is anticipated to have occurred fairly recently. Sulphate concentration decreases only little with depth in the Pleistocene to lower Miocene sediments where TOC is very low, <0.2 %. Sulphate decreases more rapidly with depth in the Oligocene to Eocene sediments where numerous relatively thin turbidites occur. The turbidites have significantly higher TOC, 0.5-1.5 %, than the interbedded hemipelagic sediments, TOC <0.2 %. High methane concentrations were not found in any of the boreholes, but the trends in sulphate and methane in boreholes indicate that high methane concentrations exist in older sediments not reached by drilling. The decollement zone is composed of lower Miocene to upper Oligocene sediments near the toe of the prism, but deepens into stratigraphically lower sediments prism ward. Thus, methane originating from these older sediments may have been brought to shallower depths by active fluid flow in the decollement.

  12. Mixing of methane and sulphate due to fluid flow in the Barbados accretionary prism

    SciTech Connect

    Laier, T.

    1996-12-31

    Methane concentrations above background level in sulphate-containing (15 mmol/l) pore waters have been observed in the d6collement zone of the Barbados accretionary prism. The peak in methane concentration in the decollement was found at a number of sites by headspace analysis of cores retrieved during ODP Legs 110 & 156 at the toe of the accretionary prism. {delta}{sup 13}C{sub 1} values between -22{per_thousand} and -36{per_thousand} indicate that methane oxidation occurs possibly due to sulphate reduction. Thus, the presence of both methane and sulphate at the same depths suggests mixing of fluids due to fluid flow. Fluid flow is also indicated by the distinct minima in chloride concentrations at the same depths. In the case of on-going methane oxidation, mixing of sulphate and methane fluids is anticipated to have occurred fairly recently. Sulphate concentration decreases only little with depth in the Pleistocene to lower Miocene sediments where TOC is very low, <0.2 %. Sulphate decreases more rapidly with depth in the Oligocene to Eocene sediments where numerous relatively thin turbidites occur. The turbidites have significantly higher TOC, 0.5-1.5 %, than the interbedded hemipelagic sediments, TOC <0.2 %. High methane concentrations were not found in any of the boreholes, but the trends in sulphate and methane in boreholes indicate that high methane concentrations exist in older sediments not reached by drilling. The decollement zone is composed of lower Miocene to upper Oligocene sediments near the toe of the prism, but deepens into stratigraphically lower sediments prism ward. Thus, methane originating from these older sediments may have been brought to shallower depths by active fluid flow in the decollement.

  13. Deformation of the Nankai Trough inner accretionary prism: The role of inherited structures

    NASA Astrophysics Data System (ADS)

    Boston, Brian; Moore, Gregory F.; Jurado, María. José; Sone, Hiroki

    2016-02-01

    Accretionary prisms commonly grow seaward, with the strata of the inner prism consisting of older, previously accreted outer prism rocks overlain by thick fore-arc basin strata. We focus on the Nankai Trough inner accretionary prism using three-dimensional (3-D) seismic data and logging data from the Integrated Ocean Drilling Program (IODP). We update the 3-D seismic volume using well velocity data to better constrain deeper horizons. Interpretation of these horizons reveals multiple folds with axial surfaces that strike near parallel to modern outer prism thrust faults, and we interpret that these folds formed as a result of thrust faulting. Reactivation of one inner prism thrust fault continued until at least ˜0.44 Ma, after the modern fore-arc basin formed, indicating that the inner prism had continued deformation until that time. Structural restorations of these folded seismic horizons demonstrate that ˜580 m of slip occurred on this steeply dipping reactivated thrust after fore-arc basin formation. Structural interpretation and analysis of logging-while-drilling data, including borehole images, in the deep inner prism revealed intense deformation of a generally homogenous lithology characterized by bedding that dips steeply (60°-90°), intersected by faults and fractures that have a range of dips and densities. Our study of the deep Kumano Basin provides new insights into the structure of the inner prism and reveals that although the inner prism has partially preserved inherited outer prism structures, these older folds and faults are steeply rotated and cut by multiple fracture populations during subsequent deformation.

  14. Fluid Overpressure and Connections to Seismicity, Cascadia Tertiary Accretionary Prism, Olympic Peninsula

    NASA Astrophysics Data System (ADS)

    Rotman, H.; Mattinson, C. G.

    2010-12-01

    Metamorphic dehydration reactions and fluid movement in accretionary prisms have been linked to the recently discovered episodic tremor and slip (ETS) earthquake events along subduction zones, but prior studies lack the detail to effectively test the hypothesis that fluid flow triggers ETS events. I conducted field work along a 52.5 km transect on the Olympic Peninsula metasedimentary accretionary prism of the Cascadia subduction zone, and collected approximately 40 representative samples of sandstone and mudrock that were buried to 6-15 km. This depth range intersects the 10-50 km depth range of ETS events. My objectives are to quantify the water flow recorded in rocks of the Olympic Peninsula via petrographic, whole rock, and isotopic analyses to test the prediction that water release increases at ~10 km depth, creating fluid overpressure needed to trigger seismicity. I calculated that on the Olympic Peninsula 1 km3 of 50% sandstone and 50% mudrock loses ~105 kg H2O/yr during burial from 6-14 km depth, comparable to the values expected from large-scale fluid budget models. Quartz veins that compose 0.5-1% of the Obstruction Peak site (~14 km burial depth) are important records of fluid flow quantity and origin. δ18O values of +11.8‰ to +15.2‰ indicate that vein H2O originated from metamorphic reactions. Flow recorded by 1 km3 of rock containing 0.5-1% quartz veins is >106 kg H2O/yr, comparable to the values 2 × 107 to 2 × 108 kg H2O/yr modeled at compositionally similar subduction zones to produce fluid overpressure conditions. I observed fibrous quartz veins, which also indicate fluid overpressure conditions were reached and support my H2O flow estimates. Therefore, Olympic Peninsula rocks at depths of ~10-14 km record dehydration and fluid overpressure large enough to trigger subduction zone seismicity.

  15. Reconciling the detrital zircon record and crustal growth within juvenile accretionary orogens

    NASA Astrophysics Data System (ADS)

    Spencer, C. J.; Cawood, P. A.; Roberts, N. M. W.

    2014-12-01

    Ancient cratons are generally characterised by Archaean cores surrounded by Proterozoic accretionary belts with large volumes of juvenile crust. Their crustal growth histories provide important insights into the genesis of continents and orogenic evolution. Whole-rock and detrital zircon isotopic studies are often used to deduce those histories, but the extent to which representative lithologies within the orogens are reliably sampled for such studies is not well established. This is especially true in cases where juvenile, zircon-poor mafic crust comprises a significant proportion of an orogen such as the East African (0.8-0.5 Ga), Namaqua-Natal (1.2-1.0 Ga), Trans-Hudson (1.9-1.8 Ga), and Kola (2.5 Ga). In particular, the Mesoproterozoic Namaqua-Natal orogenic belt (NNO) fringing the Kalahari Craton is a case in point in which Nd isotopic studies of whole-rock outcrop samples and U-Pb-Hf isotopic studies of detrital zircons from sediments of the Orange River (which drains the NNO) show different crust-formation ages and proportions of new and reworked crustal material. We hypothesise that this discrepancy is due to biasing of the detrital zircon record towards felsic rocks. Understanding the representative nature of the crustal archive preserved in detrital zircons remains critical for many studies of crustal evolution. We present data that: (a) addresses the scale of potential bias within an accretionary orogen containing large proportions of juvenile material, (b) demonstrates how the whole-rock and detrital zircon records can be reconciled for the Namaqua-Natal orogen to start, and (c) can be used to evaluate the effect of zircon bias on previous crustal growth models.

  16. Lunar ash flows - Isothermal approximation.

    NASA Technical Reports Server (NTRS)

    Pai, S. I.; Hsieh, T.; O'Keefe, J. A.

    1972-01-01

    Suggestion of the ash flow mechanism as one of the major processes required to account for some features of lunar soil. First the observational background and the gardening hypothesis are reviewed, and the shortcomings of the gardening hypothesis are shown. Then a general description of the lunar ash flow is given, and a simple mathematical model of the isothermal lunar ash flow is worked out with numerical examples to show the differences between the lunar and the terrestrial ash flow. The important parameters of the ash flow process are isolated and analyzed. It appears that the lunar surface layer in the maria is not a residual mantle rock (regolith) but a series of ash flows due, at least in part, to great meteorite impacts. The possibility of a volcanic contribution is not excluded. Some further analytic research on lunar ash flows is recommended.

  17. Ophiolites in the Xing'an-Inner Mongolia accretionary belt of the CAOB: Implications for two cycles of seafloor spreading and accretionary orogenic events

    NASA Astrophysics Data System (ADS)

    Song, Shuguang; Wang, Ming-Ming; Xu, Xin; Wang, Chao; Niu, Yaoling; Allen, Mark B.; Su, Li

    2015-10-01

    The Xing'an-Inner Mongolia accretionary belt in the southeastern segment of the Central Asian Orogenic Belt (CAOB) was produced by the long-lived subduction and eventual closure of the Paleo-Asian Ocean and by the convergence between the North China Craton and the Mongolian microcontinent. Two ophiolite belts have been recognized: the northern Erenhot-Hegenshan-Xi-Ujimqin ophiolite belt and the southern Solonker-Linxi ophiolite belt. Most basalts in the northern ophiolite belt exhibit characteristics of normal-type to enriched-type mid-ocean ridge basalt affinities with depleted Nd isotopic composition (ɛNd(t) > +5), comparable to modern Eastern Pacific mid-ocean ridge basalts. Most basaltic rocks in the southern belt show clear geochemical features of suprasubduction zone-type oceanic crust, probably formed in an arc/back-arc environment. The inferred back-arc extension along the Solonker-Linxi belt started at circa 280 Ma. Statistics of all the available age data for the ophiolites indicates two cycles of seafloor spreading/subduction, which gave rise to two main epochs of magmatic activity at 500-410 Ma and 360-220 Ma, respectively, with a gap of ~50 million years (Myr). The spatial and temporal distribution of the ophiolites and concurrent igneous rocks favor bilateral subduction toward the two continental margins in the convergence history, with final collision at ~230-220 Ma. In the whole belt, signals of continental collision and Himalayan-style mountain building are lacking. We thus conclude that the Xing'an-Inner Mongolia segment of the CAOB experienced two cycles of seafloor subduction, back-arc extension, and final "Appalachian-type" soft collision.

  18. Modeling ash dispersal of the 23 February 2013 Etna lava fountain

    NASA Astrophysics Data System (ADS)

    Poret, Matthieu; Costa, Antonio; Andronico, Daniele; Scollo, Simona; Gouhier, Mathieu

    2016-04-01

    Most plumes generated by explosive eruptions from Mt. Etna, Italy, are affected by winds towards East driving volcanic ash over the sea. It implies that erupted tephra can be collected only at proximal area around the volcano, i.e. within 20-25 km. It follows that the quantification of fine ash component and the Total Grain Size Distribution (TGSD) are very difficult and highly uncertain. Among the five lava fountain episodes occurred on the New South-East Crater of Mt. Etna, from the 17 to 23 February 2013, the 23 February paroxysmal phase lasted 1 hour and produced magma jets higher than 500 m and an eruptive plume that reached ~9 km above sea level. Winds oriented toward North-East advected the plume and produced an extended tephra fallout deposit from the slope of Etna up to Puglia region (~ 400 km from the volcano), allowing lapilli and ash to be sampled at different locations. Here, we first estimate the TGSD and the fine ash content associated to 12 samples collected after the paroxysmal episode over the entire tephra blanket. The TGSD is compared with the one related to the 12-13 January 2011 lava fountain showing a similar distribution with a mode around phi = -3. Satellite data describing the evolution of PM10 from the vent up to Calabria region were used to quantify the tail of the distribution and the fraction of the very fine ash. In order to reproduce both the field and spaceborne (MSG-SEVIRI) observations we simulated the tephra dispersal using the computational model Fall3D after modifying the TGSD by adding the fine ash component empirically. A set of simulations allowed us to assess key volcanological parameters such as the column height, the mass distribution within the plume and the effective TGSD. Best fit results indicate a Mass Eruption Rate around 1.0d+6 kg/s, a Total Erupted Mass of about 3.8d+9 kg and a PM10 fraction of ~0.73% respect to the total mass. Results lead the 23 February 2013 lava fountain episode as one of the most intense in

  19. ASH EMISSIVITY CHARACTERIZATION AND PREDICTION

    SciTech Connect

    Christopher J. Zygarlicke; Donald P. McCollor; Charlene R. Crocker

    1999-12-01

    The increased use of western subbituminous coals has generated concerns regarding highly reflective ash disrupting heat transfer in the radiant zone of pulverized-fuel boilers. Ash emissivity and reflectivity is primarily a function of ash particle size, with reflective deposits expected to consist of very small refractory ash materials such as CaO, MgO, or sulfate materials such as Na{sub 2}SO{sub 4}. For biomass fuels and biomass-coal blends, similar reflectivity issues may arise as a result of the presence of abundant organically associated calcium and potassium, which can transform during combustion to fine calcium, and potassium oxides and sulfates, which may act as reflective ash. The relationship of reflectivity to ash chemistry is a second-order effect, with the ash particle size distribution and melting point being determined by the size and chemistry of the minerals present in the starting fuel. Measurement of the emission properties of ash and deposits have been performed by several research groups (1-6) using both laboratory methods and measurements in pilot- and full-scale combustion systems. A review of the properties and thermal properties of ash stresses the important effect of ash deposits on heat transfer in the radiant boiler zone (1).

  20. Volcanic ash melting under conditions relevant to ash turbine interactions.

    PubMed

    Song, Wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado; Dingwell, Donald B

    2016-03-02

    The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200-2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines.

  1. Volcanic ash melting under conditions relevant to ash turbine interactions

    NASA Astrophysics Data System (ADS)

    Song, Wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado; Dingwell, Donald B.

    2016-03-01

    The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200-2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines.

  2. Volcanic ash melting under conditions relevant to ash turbine interactions.

    PubMed

    Song, Wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado; Dingwell, Donald B

    2016-01-01

    The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200-2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines. PMID:26931824

  3. Volcanic ash melting under conditions relevant to ash turbine interactions

    PubMed Central

    Song, Wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado; Dingwell, Donald B.

    2016-01-01

    The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200–2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines. PMID:26931824

  4. Circle of Ashes

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Circle of Ashes

    This plot tells astronomers that a pulsar, the remnant of a stellar explosion, is surrounded by a disk of its own ashes. The disk, revealed by the two data points at the far right from NASA's Spitzer Space Telescope, is the first ever found around a pulsar. Astronomers believe planets might rise up out of these stellar ashes.

    The data in this plot, or spectrum, were taken by ground-based telescopes and Spitzer. They show that light from around the pulsar can be divided into two categories: direct light from the pulsar, and light from the dusty disk swirling around the pulsar. This excess light was detected by Spitzer's infrared array camera. Dust gives off more infrared light than the pulsar because it's cooler.

    The pulsar, called 4U 0142+61, was once a massive star, until about 100,000 years ago, when it blew up in a supernova explosion and scattered dusty debris into space. Some of that debris was captured into what astronomers refer to as a 'fallback disk,' now circling the leftover stellar core, or pulsar. The disk resembles protoplanetary disks around young stars, out of which planets are thought to be born.

    The data have been corrected to remove the effects of light scattering from dust that lies between Earth and the pulsar.

    The ground-based data is from the Keck I telescope atop Mauna Kea, Hawaii.

  5. MSW fly ash stabilized with coal ash for geotechnical application.

    PubMed

    Kamon, M; Katsumi, T; Sano, Y

    2000-09-15

    The solidification and stabilization of municipal solid waste (MSW) fly ash for the purpose of minimizing the geo-environmental impact caused by toxic heavy metals as well as ensuring engineering safety (strength and soaking durability) are experimentally evaluated. The mixtures of MSW fly ash stabilized with cement and fluidized bed combustion coal fly ash (FCA) were used for unconfined compressive strength tests, leachate tests, and soaking tests. The behavior of soluble salts contained in the MSW fly ash significantly affects strength development, soaking durability, and the hardening reaction of the stabilized MSW fly ash mixtures. The cement stabilization of the MSW fly ash does not have enough effect on strength development and soaking durability. The addition of cement only contributes to the containment of heavy metals due to the high level of alkalinity. When using FCA as a stabilizing agent for MSW fly ash, the mixture exhibits high strength and durability. However, the Cd leachate cannot be prevented in the early stages of curing. Using a combination of cement and FCA as a MSW fly ash stabilizer can attain high strength, high soaking durability, and the containment of heavy metals. The stabilized MSW fly ash with cement and FCA can be practically applied to embankments. PMID:10936538

  6. Melting Behavior of Volcanic Ash relevant to Aviation Ash Hazard

    NASA Astrophysics Data System (ADS)

    Song, W.; Hess, K.; Lavallee, Y.; Cimarelli, C.; Dingwell, D. B.

    2013-12-01

    Volcanic ash is one of the major hazards caused by volcanic eruptions. In particular, the threat to aviation from airborne volcanic ash has been widely recognized and documented. In the past 12 years, more than 60 modern jet airplanes, mostly jumbo jets, have been damaged by drifting clouds of volcanic ash that have contaminated air routes and airport facilities. Seven of these encounters are known to have caused in-flight loss of engine power to jumbo jets carrying a total of more than 2000 passengers. The primary cause of engine thrust loss is that the glass in volcanic ash particles is generated at temperatures far lower than the temperatures in the combustion chamber of a jet engine ( i.e. > 1600 oC) and when the molten volcanic ash particles leave this hottest section of the engine, the resolidified molten volcanic ash particles will be accumulated on the turbine nozzle guide vanes, which reduced the effective flow of air through the engine ultimately causing failure. Thus, it is essential to investigate the melting process and subsequent deposition behavior of volcanic ash under gas turbine conditions. Although few research studies that investigated the deposition behavior of volcanic ash at the high temperature are to be found in public domain, to the best our knowledge, no work addresses the formation of molten volcanic ash. In this work, volcanic ash produced by Santiaguito volcano in Guatemala in November 8, 2012 was selected for study because of their recent activity and potential hazard to aircraft safety. We used the method of accessing the behavior of deposit-forming impurities in high temperature boiler plants on the basis of observations of the change in shape and size of a cylindrical coal ash to study the sintering and fusion phenomena as well as determine the volcanic ash melting behavior by using characteristic temperatures by means of hot stage microscope (HSM), different thermal analysis (DTA) and Thermal Gravimetric Analysis (TGA) to

  7. Ash in the Soil System

    NASA Astrophysics Data System (ADS)

    Pereira, P.

    2012-04-01

    Ash is the organic and inorganic residue produced by combustion, under laboratory and field conditions. This definition is far away to be accepted. Some researchers consider ash only as the inorganic part, others include also the material not completely combusted as charcoal or biochar. There is a need to have a convergence about this question and define clear "what means ash". After the fire and after spread ash onto soil surface, soil properties can be substantially changed depending on ash properties, that can be different according to the burned residue (e.g wood, coal, solid waste, peppermill, animal residues), material treatment before burning, time of exposition and storage conditions. Ash produced in boilers is different from the produced in fires because of the material diferent propertie and burning conditions. In addition, the ash produced in boilers is frequently treated (e.g pelletization, granulation, self curing) previously to application, to reduce the negative effects on soil (e.g rapid increase of pH, mycorrhiza, fine roots of trees and microfauna). These treatments normally reduce the rate of nutrients dissolution. In fires this does not happen. Thus the implications on soil properties are logically different. Depending on the combustion temperature and/or severity, ash could have different physical (e.g texture, wettability) and chemical properties (e.g amount and type of total and leached nutrients) and this will have implications on soil. Ash can increase and decrease soil aggregation, wettablity and water retention, bulk density, runoff and water infiltration. Normally, ash increases soil pH, Electrical Conductivity, and the amount of some basic nutrients as calcium, magnesium, sodium and potassium. However it is also a potential source of heavy metals, especially if ash pH is low. However the effect of ash on soil in space and time depends especially of the ash amount and characteristics, fire temperature, severity, topography, aspect

  8. An atlas of volcanic ash

    NASA Technical Reports Server (NTRS)

    Heiken, G.

    1974-01-01

    Volcanic ash samples collected from a variety of recent eruptions were studied, using petrography, chemical analyses, and scanning electron microscopy to characterize each ash type and to relate ash morphology to magma composition and eruption type. The ashes are best placed into two broad genetic categories: magnetic and hydrovolcanic (phreatomagmatic). Ashes from magmatic eruptions are formed when expanding gases in the magma form a froth that loses its coherence as it approaches the ground surface. During hydrovolcanic eruptions, the magma is chilled on contact with ground or surface waters, resulting in violent steam eruptions. Within these two genetic categories, ashes from different magma types can be characterized. The pigeon hole classification used here is for convenience; there are eruptions which are driven by both phreatic and magmatic gases.

  9. Tectonic imbrication of Palaeo- and Neo-Tethyan accretionary complexes in the central Pontides, Turkey

    NASA Astrophysics Data System (ADS)

    Okay, A. I.; Tuysuz, O.; Satir, M.; Eren, R. H.

    2003-04-01

    -eclogite thrust slice was previously also regarded as part of the Palaeo-Tethyan (Triassic) subduction-accretion complex. However, recent isotopic dating of the Elekdag eclogites have yielded Cretaceous ages, indicating that Palaeo- and Neo-Tethyan accretionary complexes were thrust imbricated during the Late Cretaceous subduction. A similar observation was recently reported from the Eskisehir region, 370 km to the west, where Triassic blueschists and eclogites are imbricated with the Upper Cretaceous accretionary complexes. Close association of Paleo- and Neo-Tethyan accretionary complexes along the Izmir-Ankara suture indicates that the latest Triassic-earliest Jurassic Cimmeride orogeny in Turkey was of accretional rather than collisional nature, and that the Izmir-Ankara suture represents a long-lived plate boundary of late Palaeozoic to early Tertiary age.

  10. Understanding tectonic stress and rock strength in the Nankai Trough accretionary prism, offshore SW Japan

    NASA Astrophysics Data System (ADS)

    Huffman, Katelyn A.

    Understanding the orientation and magnitude of tectonic stress in active tectonic margins like subduction zones is important for understanding fault mechanics. In the Nankai Trough subduction zone, faults in the accretionary prism are thought to have historically slipped during or immediately following deep plate boundary earthquakes, often generating devastating tsunamis. I focus on quantifying stress at two locations of interest in the Nankai Trough accretionary prism, offshore Southwest Japan. I employ a method to constrain stress magnitude that combines observations of compressional borehole failure from logging-while-drilling resistivity-at-the-bit generated images (RAB) with estimates of rock strength and the relationship between tectonic stress and stress at the wall of a borehole. I use the method to constrain stress at Ocean Drilling Program (ODP) Site 808 and Integrated Ocean Drilling Program (IODP) Site C0002. At Site 808, I consider a range of parameters (assumed rock strength, friction coefficient, breakout width, and fluid pressure) in the method to constrain stress to explore uncertainty in stress magnitudes and discuss stress results in terms of the seismic cycle. I find a combination of increased fluid pressure and decreased friction along the frontal thrust or other weak faults could produce thrust-style failure, without the entire prism being at critical state failure, as other kinematic models of accretionary prism behavior during earthquakes imply. Rock strength is typically inferred using a failure criterion and unconfined compressive strength from empirical relations with P-wave velocity. I minimize uncertainty in rock strength by measuring rock strength in triaxial tests on Nankai core. I find strength of Nankai core is significantly less than empirical relations predict. I create a new empirical fit to our experiments and explore implications of this on stress magnitude estimates. I find using the new empirical fit can decrease stress

  11. Precambrian accretionary history and phanerozoic structures-A unified explanation for the tectonic architecture of the nebraska region, USA

    USGS Publications Warehouse

    Carlson, M.P.

    2007-01-01

    The Phanerozoic history in Nebraska and adjacent regions contains many patterns of structure and stratigraphy that can be directly related to the history of the Precambrian basement rocks of the area. A process is proposed that explains the southward growth of North America during the period 1.8-1.6 Ga. A series of families of accretionary events during the Proterozoic emplaced sutures that remained as fundamental basement weak zones. These zones were rejuvenated in response to a variety of continental stress events that occurred during the Phanerozoic. By combining the knowledge of basement history with the history of rejuvenation during the Phanerozoic, both the details of Proterozoic accretionary growth and an explanation for the patterns of Phanerozoic structure and stratigraphy is provided. ?? 2007 The Geological Society of America. All rights reserved.

  12. Linking collisional and accretionary orogens during Rodinia assembly and breakup: Implications for models of supercontinent cycles

    NASA Astrophysics Data System (ADS)

    Cawood, Peter A.; Strachan, Robin A.; Pisarevsky, Sergei A.; Gladkochub, Dmitry P.; Murphy, J. Brendan

    2016-09-01

    Periodic assembly and dispersal of continental fragments has been a characteristic of the solid Earth for much of its history. Geodynamic drivers of this cyclic activity are inferred to be either top-down processes related to near surface lithospheric stresses at plate boundaries or bottom-up processes related to mantle convection and, in particular, mantle plumes, or some combination of the two. Analysis of the geological history of Rodinian crustal blocks suggests that internal rifting and breakup of the supercontinent were linked to the initiation of subduction and development of accretionary orogens around its periphery. Thus, breakup was a top-down instigated process. The locus of convergence was initially around north-eastern and northern Laurentia in the early Neoproterozoic before extending to outboard of Amazonia and Africa, including Avalonia-Cadomia, and arcs outboard of Siberia and eastern to northern Baltica in the mid-Neoproterozoic (∼760 Ma). The duration of subduction around the periphery of Rodinia coincides with the interval of lithospheric extension within the supercontinent, including the opening of the proto-Pacific at ca. 760 Ma and the commencement of rifting in east Laurentia. Final development of passive margin successions around Laurentia, Baltica and Siberia was not completed until the late Neoproterozoic to early Paleozoic (ca. 570-530 Ma), which corresponds with the termination of convergent plate interactions that gave rise to Gondwana and the consequent relocation of subduction zones to the periphery of this supercontinent. The temporal link between external subduction and internal extension suggests that breakup was initiated by a top-down process driven by accretionary tectonics along the periphery of the supercontinent. Plume-related magmatism may be present at specific times and in specific places during breakup but is not the prime driving force. Comparison of the Rodinia record of continental assembly and dispersal with that

  13. A Three-dimensional Reflection Seismic Survey In The Earstern Nankai Accretionary Prism.

    NASA Astrophysics Data System (ADS)

    Ike, T.; Tokuyama, H.; Kuramoto, S.; Matsushima, J.; Yokota, T.; Pascal, G.; Lalememant, S.

    The Three-Dimensional Multi-Channel Seismic (3D-MCS) reflection survey using a tuned air gun source was held in the eastern Nankai accretionary prism from June to July 2000. The crustal deformation of the eastern Nankai accretionary prism is affected by a nearby collision between the Izu-Bonin arc and the central Japan. Sev- eral active fault systems were described by many high-resolution seismic data, and proposed that the Tokai and Kodaiba fault systems were derived from a decollement plane. From the deformation style in the Nankai Trough, we concern about the oc- currence of a great earthquake in recent years. The main objective of our experiment is to resolve the structural image of the plate boundary and identify the up-dip limit of seismogenic zone. The 3-D survey covers 45km long and 5km wide area with 51 seismic lines, located about 50km southwest from Omaezaki. We applied the non- iterative Kirchhoff pre-stack time migration method (Matsushima et.,al 2001) with stacking velocity analysis to our 3-D data. The derived 3-D prestack time migra- tion profile shows a better development at the deep structure on the top of oceanic crust, compared with preliminary 2-D prestack time migration processed profile. The processed 3-D data gives us a significantly clear image of the thrust faults and the relationship between sediment deformation and thrust activity. A preliminary 3-D in- terpretation was conducted and leaded the following results.1) The Tokai and Kodaiba thrusts are confirmed to be sets of out-of-sequence thrusts. 2) Both thrusts are ac- tive fault that revealed by the structure of the deformation of surface sediments. 3) A strong and low frequency reflector can be identified in the entire profile at two-way- time 7-7.5sec that should be a decollement plane. 4)Tokai and Kodaiba fault systems merged to the decollement plane at same depth. The contact area of the thrust faults to the decollement corresponds to south end of seismic coupling region presumed

  14. Reconstructing the Lethal Part of the 1790 Eruption at Kilauea

    NASA Astrophysics Data System (ADS)

    Swanson, D.; Weaver, S. J.; Houghton, B. F.

    2011-12-01

    The most lethal known eruption from a volcano in the United States took place in November 1790 at Kilauea, killing perhaps 400-800 people (estimates range widely) who were crossing the summit on their way to a distant battle site. The eruption culminated ca. 300 years of sporadic explosive activity after the formation of Kilauea Caldera in about 1500. No contemporary account exists of the 1790 activity, but an eruption plume was observed from Kawaihae, 100 km NW of Kilauea, that probably was 10 km or higher. We are attempting to piece together the lethal event from a study of the 1790 and enclosing deposits and by using published accounts, written several decades later, based on interviews with survivors or others with knowledge of the tragedy. Determining what deposits actually formed in November 1790 is crucial. The best tie to that date is a deposit of phreatomagmatic lithic lapilli and ash that occurs SE of the caldera and must have been advected by high-level (>~10 km) westerly winds rather than low-level NE trade winds. It is the only contender for deposits from the high column observed in 1790. Small lapilli from the high column fell onto, and sank deeply into, a 3-5-cm-thick accretionary lapilli layer that was wet and likely no more than a few hours old. The wet ash occurs south of the caldera, where the lithic lapilli fell into it, and is also found west of the caldera in the saddle between Kilauea and Mauna Loa, where the victims were probably walking along a main foot trail still visible today. A lithic pyroclastic surge swept across the saddle, locally scouring away the wet accretionary lapilli layer but generally leaving a deposit <1 to 15 cm thick on the ash and embedding 1-cm lithic lapilli deeply within it. This indicates that the surge also erupted in November 1790, while the underlying ash was still wet. Though scattered ballistic blocks later fell in the area, the surge left the youngest continuous deposit on the west flank of Kilauea. An account

  15. Ameliorative effect of fly ashes

    SciTech Connect

    Bhumbla, D.K.

    1991-01-01

    Agronomic effectiveness and environmental impact of fly ashes used to reclaim pyritic acid mine spoils were investigated in the laboratory and field. Mine spoils at two abandoned sites were amended with three rates of fly ash, three rates of rock phosphate, and seeded with alfalfa and wheat. Application of fly ash decreased bulk density and increased moisture retention capacity of spoils. Fly ash application reduced cation exchange capacity, acidity, toxic levels of Al, Fe, and Mn in soils by buffering soil pH at 6.5, and retarded pyrite oxidation. The reduction in cation exchange capacity was compensated by release of plant nutrients through diffusion and dissolution of plerospheres in fly ash. Improvement of spoil physical, chemical and microbial properties resulted in higher yield, more nitrogen fixation, and utilization of P from rock phosphate by alfalfa. Laboratory investigations demonstrated that neutralization potential and the amounts of amorphous oxides of iron were more important for classifying fly ashes than the total elemental analysis presently used in a taxonomic classification system. Contamination of the food chain through plant removal of Mo and As in fly ash treated mine spoils was observed only for Mo and only for the first year of cropping. Plant available As and Mo decreased with time. Laboratory leaching and adsorption studies and a field experiment showed that trace metals do not leach from fly ashes at near neutral pH and more oxyanions will leach from fly ashes with low neutralization potential and low amounts of amorphous oxides of iron.

  16. Paleozoic accretionary orogenesis in the eastern Beishan orogen: constraints from zircon U-Pb and 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Ao, Songjian; Xiao, Wenjiao; Windley, Brian; Mao, Qigui

    2016-04-01

    The continental growth mechanism of the Altaids in Central Asia is still in controversy between models of continuous subduction-accretion versus punctuated accretion by closure of multiple oceanic basins. The Beishan orogenic belt, located in the southern Altaids, is a natural laboratory to address this controversy. Key questions that are heavily debated are: the closure time and subduction polarity of former oceans, the emplacement time of ophiolites, and the styles of accretion and collision. This paper reports new structural data, zircon ages and Ar-Ar dates from the eastern Beishan Orogen that provide information on the accretion process and tectonic affiliation of various terranes. Our geochronological and structural results show that the younging direction of accretion was northwards and the subduction zone dipped southwards under the northern margin of the Shuangyingshan micro-continent. This long-lived and continuous accretion process formed the Hanshan accretionary prism. Our field investigations show that the emplacement of the Xiaohuangshan ophiolite was controlled by oceanic crust subduction beneath the forearc accretionary prism of the Shuangyingshan-Mazongshan composite arc to the south. Moreover, we address the age and terrane affiliation of lithologies in the eastern Beishan orogen through detrital zircon geochronology of meta-sedimentary rocks. We provide new information on the ages, subduction polarities, and affiliation of constituent structural units, as well as a new model of tectonic evolution of the eastern Beishan orogen. The accretionary processes and crustal growth of Central Asia were the result of multiple sequences of accretion and collision of manifold terranes. Reference: Ao, S.J., Xiao, W., Windley, B.F., Mao, Q., Han, C., Zhang, J.e., Yang, L., Geng, J., Paleozoic accretionary orogenesis in the eastern Beishan orogen: Constraints from zircon U-Pb and 40Ar/39Ar geochronology. Gondwana Research, doi: http://dx.doi.org/10.1016/j

  17. Thrust fault segmentation and downward fault propagation in accretionary wedges: New Insights from 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Orme, Haydn; Bell, Rebecca; Jackson, Christopher

    2016-04-01

    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. Although we often assume imbricate faults are likely to have propagated upwards from the décollement we show strong evidence for fault nucleation at shallow depths and downward propagation to intersect the décollement. The complex fault interactions documented here have implications for hydraulic compartmentalisation and pore

  18. An evaluation of factors influencing pore pressure in accretionary complexes: Implications for taper angle and wedge mechanics

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    2006-01-01

    At many subduction zones, accretionary complexes form as sediment is off-scraped from the subducting plate. Mechanical models that treat accretionary complexes as critically tapered wedges of sediment demonstrate that pore pressure controls their taper angle by modifying basal and internal shear strength. Here, we combine a numerical model of groundwater flow with critical taper theory to quantify the effects of sediment and de??collement permeability, sediment thickness, sediment partitioning between accretion and underthrusting, and plate convergence rate on steady state pore pressure. Our results show that pore pressure in accretionary wedges can be viewed as a dynamically maintained response to factors which drive pore pressure (source terms) and those that limit flow (permeability and drainage path length). We find that sediment permeability and incoming sediment thickness are the most important factors, whereas fault permeability and the partitioning of sediment have a small effect. For our base case model scenario, as sediment permeability is increased, pore pressure decreases from near-lithostatic to hydrostatic values and allows stable taper angles to increase from ??? 2.5?? to 8??-12.5??. With increased sediment thickness in our models (from 100 to 8000 m), increased pore pressure drives a decrease in stable taper angle from 8.4??-12.5?? to 15?? to <4??) with increased sediment thickness (from <1 to 7 km). One key implication is that hydrologic properties may strongly influence the strength of the crust in a wide range of geologic settings. Copyright 2006 by the American Geophysical Union.

  19. Fly ash quality and utilization

    SciTech Connect

    Barta, L.E.; Lachner, L.; Wenzel, G.B.; Beer, M.J.

    1995-12-01

    The quality of fly ash is of considerable importance to fly ash utilizers. The fly ash puzzolanic activity is one of the most important properties that determines the role of fly ash as a binding agent in the cementing process. The puzzolanic activity, however is a function of fly ash particle size and chemical composition. These parameters are closely related to the process of fly ash formation in pulverized coal fired furnaces. In turn, it is essential to understand the transformation of mineral matter during coal combustion. Due to the particle-to-particle variation of coal properties and the random coalescence of mineral particles, the properties of fly ash particles e.g. size, SiO{sub 2} content, viscosity can change considerably from particle to particle. These variations can be described by the use of the probability theory. Since the mean values of these randomly changing parameters are not sufficient to describe the behavior of individual fly ash particles during the formation of concrete, therefore it is necessary to investigate the distribution of these variables. Examples of these variations were examined by the Computer Controlled Scanning Electron Microscopy (CCSEM) for particle size and chemical composition for Texas lignite and Eagel Butte mineral matter and fly ash. The effect of combustion on the variations of these properties for both the fly ash and mineral matter were studied by using a laminar flow reactor. It is shown in our paper, that there are significant variations (about 40-50% around the mean values) of the above-listed properties for both coal samples. By comparing the particle size and chemical composition distributions of the mineral matter and fly ash, it was possible to conclude that for the Texas lignite mineral matter, the combustion did not effect significantly the distribution of these properties, however, for the Eagel Butte coal the combustion had a major impact on these mineral matter parameters.

  20. Human Footprints in Relation to the 1790 Eruption of Kilauea

    NASA Astrophysics Data System (ADS)

    Swanson, D. A.; Rausch, J.

    2008-12-01

    In 1790, a party of warriors and their families was decimated by an explosive eruption of Kilauea; fatality estimates range from about 80 to 5,405. In 1920, thousands of footprints made by barefoot walkers in wet accretionary lapilli ash were found within a few kilometers southwest of Kilauea's summit. In 1921, Jaggar related the footprints to survivors or rescuers of the 1790 eruption, mainly because he assumed that few people visited the supposedly forbidden area except in 1790. Archaeologists from Hawai'i Volcanoes National Park recently questioned whether the footprints were made at that time and by warriors, citing a wide range of directions that people were walking and evidence of extensive human use of the area. Forensic and anthropologic studies indicate that a human foot is about 15 percent of an individual's height. A man's foot may be slightly more that 15 percent, a women's slightly less, but nonetheless the height can be estimated to within a few centimeters. We measured the heel-big toe length of more than 400 footprints and calculated an average height of 1.5 m, including some children only a little more than 1 m tall. Few calculated heights are 1.75 m or more. Early Europeans described Hawaiian warriors as tall, one missionary estimating an average height of 1.78 m. A footprint may be larger than a foot, particularly in slippery, wet ash, so our estimates of heights are probably somewhat too large. The data indicate that most of the footprints were made by women and children, not by men, much less warriors. We traced the footprint-bearing ash into the tephra section on the southwest side of Kilauea's caldera. It occurs high in the section, resting on older explosive deposits. Its surface is indented by small lithic lapilli, which fell into the ash while it was still wet; a few even landed in footprints. The lithic lapilli are at the edge of a thick block and lapilli deposit that fell from a high eruption column; the column reached well into the jet

  1. A two-dimensional model of the methane cycle in a sedimentary accretionary wedge

    NASA Astrophysics Data System (ADS)

    Archer, D. E.; Buffett, B. A.

    2012-03-01

    A two-dimensional model of sediment column geophysics and geochemistry has been adapted to the problem of an accretionary wedge formation, patterned after the margin of the Juan de Fuca plate as it subducts under the North American plate. Much of the model description was given in a companion paper about application of the model to a passive margin setting; here we build on that formulation to simulate the deformation of the sediment wedge as it approaches the subduction zone. The active margin configuration of the model shares sensitivities with the passive margin configuration, in that sensitivities to organic carbon deposition and respiration kinetics, and to vertical bubble transport and redissolution in the sediment, are stronger than the sensitivity to ocean temperature. The active margin simulation also shows a sensitivity to plate subduction velocity, with higher plate velocities producing less hydrate per meter of coastline than slower velocities or the passive margin configuration. However, the local hydrate concentrations, as pore volume saturation, are higher in the active setting than the passive, as generally observed in the field.

  2. A two-dimensional model of the methane cycle in a sedimentary accretionary wedge

    NASA Astrophysics Data System (ADS)

    Archer, D. E.; Buffett, B. A.

    2012-08-01

    A two-dimensional model of sediment column geophysics and geochemistry has been adapted to the problem of an accretionary wedge formation, patterned after the margin of the Juan de Fuca plate as it subducts under the North American plate. Much of the model description is given in a companion paper about the application of the model to an idealized passive margin setting; here we build on that formulation to simulate the impact of the sediment deformation, as it approaches the subduction zone, on the methane cycle. The active margin configuration of the model shares sensitivities with the passive margin configuration, in that sensitivities to organic carbon deposition and respiration kinetics, and to vertical bubble transport and redissolution in the sediment, are stronger than the sensitivity to ocean temperature. The active margin simulation shows a complex sensitivity of hydrate inventory to plate subduction velocity, with results depending strongly on the geothermal heat flux. In low heat-flux conditions, the model produces a larger inventory of hydrate per meter of coastline in the passive margin than active margin configurations. However, the local hydrate concentrations, as pore volume saturation, are higher in the active setting than in the passive, as generally observed in the field.

  3. Hydrocarbon gas potential of accretionary melange terranes: an example from the olympic peninsula, Washington

    SciTech Connect

    Kvenvolden, K.A.; Snavely, P.D. Jr.

    1985-01-01

    Convergence between the oceanic and North American plates during middle late Eocene and late middle Miocene times produced two principal accretionary terranes of melange and broken formation on the continental margin of Washington. Hydrocarbon analyses of these melange units were undertaken to evaluate their source rock potential for oil and gas and to assess the generative processes operating in these thick melange wedges. The results of pyrolysis, vitrinite reflectance, and visual kerogen analyses of samples of these melanges are consistent and in good agreement, showing mainly Type III organic matter that is marginally mature to mature with respect to gas generation. Coastal exposure of Ozette melange commonly have a petroliferous odor which contains methane through at least the pentanes as prominent constitutents. Hydrocarbon gases from seeps and from an abandoned well in the study area have been molecular compositions and methane carbon isotopic values indicating related sources. The authors evidence suggest that the Ozette assemblage melange is the principal source for thermogenic hydrocarbon gases. Potential exploration targets may exist in western Washington where melange and broken formation are thrust beneath the Eocene oceanic crust (Crescent Formation). Gas generated from the underplated rocks could have migrated through the upper plate into structures in the Tertiary strata that overlie these Eocene basalts.

  4. Biogas production using anaerobic groundwater containing a subterranean microbial community associated with the accretionary prism

    PubMed Central

    Baito, Kyohei; Imai, Satomi; Matsushita, Makoto; Otani, Miku; Sato, Yu; Kimura, Hiroyuki

    2015-01-01

    In a deep aquifer associated with an accretionary prism, significant methane (CH4) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH4 and hydrogen (H2) using anaerobic groundwater collected from the deep aquifer. To generate CH4, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H2 was detected and accumulated in the gas phase of the bioreactor. After the H2 decreased, rapid CH4 production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H2-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H2-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH4 production. For H2 production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H2 was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H2-producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community. PMID:25267392

  5. Rock varnish in New York: An accelerated snapshot of accretionary processes

    NASA Astrophysics Data System (ADS)

    Krinsley, David H.; Dorn, Ronald I.; DiGregorio, Barry E.; Langworthy, Kurt A.; Ditto, Jeffrey

    2012-02-01

    Samples of manganiferous rock varnish collected from fluvial, bedrock outcrop and Erie Barge Canal settings in New York state host a variety of diatom, fungal and bacterial microbial forms that are enhanced in manganese and iron. Use of a Dual-Beam Focused Ion Beam Scanning Electron Microscope to manipulate the varnish in situ reveals microbial forms that would not have otherwise been identified. The relative abundance of Mn-Fe-enriched biotic forms in New York samples is far greater than varnishes collected from warm deserts. Moisture availability has long been noted as a possible control on varnish growth rates, a hypothesis consistent with the greater abundance of Mn-enhancing bioforms. Sub-micron images of incipient varnish formation reveal that varnishing in New York probably starts with the mortality of microorganisms that enhanced Mn on bare mineral surfaces; microbial death results in the adsorption of the Mn-rich sheath onto the rock in the form of filamentous networks. Clay minerals are then cemented by remobilization of the Mn-rich material. Thus, the previously unanswered question of what comes first - clay mineral deposition or enhancement of Mn - can be answered in New York because of the faster rate of varnish growth. In contrast, very slow rates of varnishing seen in warm deserts, of microns per thousand years, make it less likely that collected samples will reveal varnish accretionary processes than samples collected from fast-accreting moist settings.

  6. Biogas production using anaerobic groundwater containing a subterranean microbial community associated with the accretionary prism.

    PubMed

    Baito, Kyohei; Imai, Satomi; Matsushita, Makoto; Otani, Miku; Sato, Yu; Kimura, Hiroyuki

    2015-09-01

    In a deep aquifer associated with an accretionary prism, significant methane (CH₄) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH₄ and hydrogen (H₂) using anaerobic groundwater collected from the deep aquifer. To generate CH₄, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H₂ was detected and accumulated in the gas phase of the bioreactor. After the H₂ decreased, rapid CH₄ production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H₂ -producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H₂ -producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH₄ production. For H₂ production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H₂ was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H₂ -producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community. PMID:25267392

  7. Ferromanganese nodules from MANOP Sites H, S, and R-Control of mineralogical and chemical composition by multiple accretionary processes

    USGS Publications Warehouse

    Dymond, J.; Lyle, M.; Finney, B.; Piper, D.Z.; Murphy, K.; Conard, R.; Pisias, N.

    1984-01-01

    The chemical composition of ferromanganese nodules from the three nodule-bearing MANOP sites in the Pacific can be accounted for in a qualitative way by variable contributions of distinct accretionary processes. These accretionary modes are: 1. (1) hydrogenous, i.e., direct precipitation or accumulation of colloidal metal oxides in seawater, 2. (2) oxic diagenesis which refers to a variety of ferromanganese accretion processes occurring in oxic sediments; and 3. (3) suboxic diagenesis which results from reduction of Mn+4 by oxidation of organic matter in the sediments. Geochemical evidence suggests processes (1) and (2) occur at all three MANOP nodule-bearing sites, and process (3) occurs only at the hemipelagic site, H, which underlies the relatively productive waters of the eastern tropical Pacific. A normative model quantitatively accounts for the variability observed in nearly all elements. Zn and Na, however, are not well explained by the three end-member model, and we suggest that an additional accretionary process results in greater variability in the abundances of these elements. Variable contributions from the three accretionary processes result in distinct top-bottom compositional differences at the three sites. Nodule tops from H are enriched in Ni, Cu, and Zn, instead of the more typical enrichments of these elements in nodule bottoms. In addition, elemental correlations typical of most pelagic nodules are reversed at site H. The three accretionary processes result in distinct mineralogies. Hydrogenous precipitation produces ??MnO2. Oxic diagenesis, however, produces Cu-Ni-rich todorokite, and suboxic diagenesis results in an unstable todorokite which transforms to a 7 A?? phase ("birnessite") upon dehydration. The presence of Cu and Ni as charge-balancing cations influence the stability of the todorokite structure. In the bottoms of H nodules, which accrete dominantly by suboxic diagenesis, Na+ and possibly Mn+2 provide much of the charge balance for

  8. Volcanic ash - Terrestrial versus extraterrestrial

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.

    1976-01-01

    A principal difference between terrestrial and extraterrestrial lavas may consist in the greater ability of terrestrial lavas to form thin films (like those of soap bubbles) and hence foams. It would follow that, in place of the pumice and spiny shards found in terrestrial volcanic ash, an extraterrestrial ash should contain minute spherules. This hypothesis may help to explain lunar microspherules.

  9. Incineration and incinerator ash processing

    SciTech Connect

    Blum, T.W.

    1991-01-01

    Parallel small-scale studies on the dissolution and anion exchange recovery of plutonium from Rocky Flats Plant incinerator ash were conducted at the Los Alamos National Laboratory and at the Rocky Flats Plant. Results from these two studies are discussed in context with incinerator design considerations that might help to mitigate ash processing related problems. 11 refs., 1 fig., 1 tab.

  10. Trace elements in coal ash

    USGS Publications Warehouse

    Deonarine, Amrika; Kolker, Allan; Doughten, Michael W.

    2015-01-01

    In this fact sheet, the form, distribution, and behavior of trace elements of environmental interest in samples of coal fly ash were investigated in response to concerns about element mobility in the event of an ash spill. The study includes laboratory-based leaching experiments to examine the behavior of trace elements, such as arsenic (As) and chromium (Cr), in response to key environmental factors including redox conditions (degree of oxygenation), which are known to vary with depth within coal ash impoundments and in natural ecosystems. The experiments show that As dissolves from samples of coal fly ash into simulated freshwater under both oxic (highly oxygenated) and anoxic (poorly oxygenated) conditions, whereas dissolved Cr concentrations are very redox dependent. This U.S. Geological Survey research helps define the distribution of elements such as As in coal ash and shows that element mobility can vary considerably under different conditions expected in the environment.

  11. Redistribution of material and formation of polygenic mélanges in the External Ligurian accretionary complex (Northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Codegone, G.; Festa, A.; Dilek, Y.; Pini, G.

    2011-12-01

    Tectonic, sedimentary and diapiric processes may strongly control the dynamics of the shallower part of subduction-accretionary complexes, and formation of polygenic mélanges at different scales. In modern accretionary complexes, drill cores and seismic images provide in-situ samples and measurements about large-scale features, and crucial informations on the structural processes that control their dynamics. However, minor-scale geological features and processes that are responsible for their formation are still difficult to decipher based on these techniques alone. On-land, exhumed accretionary complexes, on the other hand, can provide essential informations at all scales about (i) 3D features and structural architecture of mélanges, (ii) the role and interplay of different processes of mélange formation, and (iii) the redistribution of material in shallower parts of accretionary complexes (Festa et al., 2010). Detailed structural-stratigraphic observations in the exhumed Ligurian accretionary complex in the westernmost Northern Apennines show that a larger part of it (i.e., the Argille varicolori Formation) represents a composite chaotic unit consisting of diverse scale mélange types formed by tectonic, sedimentary and diapiric processes and their mutual superposition. Here, the spatial and temporal relationships between these mélange types resulted from two main episodes of deformation: (i) late Cretaceous-middle Eocene accretion, producing tectonic deformation of sediments at the wedge-front and formation of tectonically disrupted bodies through layer-parallel extension and contraction. Episodes of dynamic instability of the wedge-front alternating with steady-state accretion caused the removal of material locally and the subsequent emplacement of gravity-driven chaotic bodies within the tectonically disrupted bodies; (ii) late Oligocene-middle Miocene out-of-sequence thrusting, overprinting the previously formed chaotic bodies and producing a new and

  12. Geological Controls of a Gas-Hydrate System in the Frontal Taiwan Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Liao, W.; Lin, A.; Liu, C.; Hsu, S.; Lin, C.; Chen, G.; Schn Êrle, P.

    2008-12-01

    The frontal accretionary wedge offshore southwest Taiwan is characterized by rapid sedimentation, erosion along submarine canyons, and tectonic uplift due to folding and thrusting. The possible existence of gas hydrates beneath the seafloor has been indicated by geophysical and geological data. The interplays between the processes of sedimentation, erosion, and tectonic uplift therefore maintain a dynamic equilibrium system in which gas hydrates are preserved in the strata. In order to understand this system, we use data of chirp sonar, reflection seismics, and seafloor sediment samples to characterize the geological controls on the gas-hydrate system in the study area. The study area lies in the lower slope domain of the accretionary wedge. Seismic data reveals that, in the west of the study area (i.e., the frontal segment), it consists of a series of folds cored by blind thrusts; in the east of the study area (i.e., the rear segment), it consists of an array of emergent thrusts. The most frontal emergent thrust separates the frontal and rear segments of the lower slope. There are different in sedimentary features, structural styles, distributions of bottom simulating reflectors (BSRs) in the frontal and rear segments. In the frontal segment, sedimentation prevails in this region. Areas of major erosion and mass-wasting processes occur mostly in the reaches of submarine canyons. The spatial distribution of BSRs is sparse in this region and BSRs occur mostly beneath the anticlinal and bathymetric ridges. In the rear segment, it typically shows west-vergent and asymmetric fold profiles with long and planar backlimbs versus short forelimbs. The forelimbs are absent or very short in profile, and the east-dipping backlimbs are steeper beneath bathymetric ridge with its stratal dip decreasing and exhibit a homoclinal feature. There is usually a significant stratigraphic section deposited on backlimbs, showing evidences of limb rotation during fold growth. A few seafloor

  13. SW Grenville Province, Canada: the case against post 1.4 Ga accretionary tectonics

    NASA Astrophysics Data System (ADS)

    Hanmer, S.; Corrigan, D.; Pehrsson, S.; Nadeau, L.

    2000-03-01

    Seven accretionary sutures, formed between 1.16 and 1.03 Ga, have been identified by different authors in the Ontario-Quebec-Adirondack (OQA) segment of the Mesoproterozoic Grenville orogen in Canada. With one exception, the inferred accretionary terrane boundaries lie within, or at the margins of the Central Metasedimentary Belt (CMB), located between the Central Gneiss Belt and the Adirondack Highlands (Central Granulite Terrane). However, geological, geochronological, and petrological data suggest that the Grenville orogen on both sides of the proposed terrane boundaries (sutures) preserves a common 1.4-1.03 Ga tectonomagmatic history, inconsistent with its origin as a post-1.4 Ga collage of exotic tectonic blocks. Features which straddle the proposed 1.16-1.03 Ga 'sutures', from the Central Gneiss Belt, via the Adirondack Highlands, to the Mauricie area, include: (1) Mesoproterozoic continental crust (1.5-1.4 Ga) forming the host and/or basement to younger magmatic and supracrustal suites. (2) A 1.35-1.3 Ga continental arc, remnants of which occur from the CMB boundary zone (CMBBZ) in Ontario to the Appalachians in the United States, built on the 1.5-1.4 Ga continental crust. (3) Intrusions of 1.17-1.13 Ga age in the Central Gneiss Belt (mafic suite), and the Adirondack Highlands and their Quebec extension (AMCG suite, i.e. anorthosite massifs and related granitoids). (4) Relics of 1.18-1.14 Ga sedimentary basins in the northwestern CMB and the Mauricie area. We propose that an alternative model can adequately account for the observed geology of this part of the Grenville orogen wherein, the rocks of the OQA segment were part of an Andean-type margin between 1.4 and 1.2 Ga. At 1.35-1.3 Ga, a continental magmatic arc was built upon the southeastern margin of Laurentia represented by the 1.5-1.4 Ga Mesoproterozoic continental crust. The arc split at 1.3 Ga forming an ensialic back arc basin, relics of which now occur in the northwestern part of the CMB, and the

  14. Detrital zircon geochronology and provenance analysis applied to the onshore Makran accretionary wedge, SE Iran

    NASA Astrophysics Data System (ADS)

    Mohammadi, A.; Burg, J.; Winkler, W.; Ruh, J. B.; Von Quadt, A.

    2013-12-01

    The Makran is one of the largest accretionary wedges in the world, located in Southeast Iran. The Makran Basin is composed of turbidity sediments ranging in age from late Cretaceous to Holocene. The analysis of detrital zircons is important to interpret the provenance of the sediments and to clarify the geological history of the sedimentary basins and their surrounding source regions. We present about 2777 new U-Pb ages (ICP laser ablation mass spectrometry) from individual detrital zircons of 18 sandstone samples collected throughout the onshore Makran. 101 detrital zircon ages from a late Cretaceous fine grained sandstone ranges from 180-160 Ma (Mid-Jurassic). 478 detrital zircon ages obtained from the mid to late Eocene sandstone reveals different sources for the NE and NW parts of the Makran Basin. Zircon grains in the NE basin belong to two populations peaked at Mid-Jurassic and Mid-Eocene, with the noticeable absence of Cretaceous grains. In the NW basin, detrital zircons are Mid-Cretaceous to Mid-Eocene. 587 detrital zircon grains from fine to medium grained Oligocene sandstones collected in different parts of the basin range from Mid-Cretaceous to Mid-Eocene. 1611 detrital zircon age from Early Miocene sandstones collected in the eastern and western parts of the basin show distinctly different detrital zircon ages. They range from Mid-Cretaceous to Mid-Eocene in the eastern basin, from Late Cretaceous to Mid-Eocene in the west. Detrital zircon ages from Mid and Late Miocene sandstones rang from Late Cretaceous to Mid-Eocene. These new detrital zircon U-Pb age data show that the eastern and western parts of the Makran Basin received sediments from different source areas during Eocene and Early Miocene times. Mid and Late Miocene sediment are recycled (cannibalism) from the Oligocene units of the basin.

  15. Fluid expulsion sites on the Cascadia accretionary prism: mapping diagenetic deposits with processed GLORIA imagery

    USGS Publications Warehouse

    Carson, Bobb; Seke, Erol; Paskevich, Valerie F.; Holmes, Mark L.

    1994-01-01

     Point-discharge fluid expulsion on accretionary prisms is commonly indicated by diagenetic deposition of calcium carbonate cements and gas hydrates in near-surface (<10 m below seafloor; mbsf) hemipelagic sediment. The contrasting clastic and diagenetic lithologies should be apparent in side scan images. However, sonar also responds to variations in bottom slope, so unprocessed images mix topographic and lithologic information. We have processed GLORIA imagery from the Oregon continental margin to remove topographic effects. A synthetic side scan image was created initially from Sea Beam bathymetric data and then was subtracted iteratively from the original GLORIA data until topographic features disappeared. The residual image contains high-amplitude backscattering that we attribute to diagenetic deposits associated with fluid discharge, based on submersible mapping, Ocean Drilling Program drilling, and collected samples. Diagenetic deposits are concentrated (1) near an out-of-sequence thrust fault on the second ridge landward of the base of the continental slope, (2) along zones characterized by deep-seated strikeslip faults that cut transversely across the margin, and (3) in undeformed Cascadia Basin deposits which overlie incipient thrust faults seaward of the toe of the prism. There is no evidence of diagenetic deposition associated with the frontal thrust that rises from the dècollement. If the dècollement is an important aquifer, apparently the fluids are passed either to the strike-slip faults which intersect the dècollement or to the incipient faults in Cascadia Basin for expulsion. Diagenetic deposits seaward of the prism toe probably consist dominantly of gas hydrates

  16. 3D stability of accretionary wedges by application of the maximum strength theorem

    NASA Astrophysics Data System (ADS)

    Souloumiac, P.; Leroy, Y. M.; Krabbenhoft, K.; Maillot, B.

    2009-04-01

    The objective is to capture the 3D failure modes in accretionary wedges and their analogue experiments in the laboratory from the sole knowledge of the material and interface strengths. The proposed methodology relies on the maximum strength theorem inherited from classical limit analysis. The virtual velocity field is constructed by spatial discretization. The numerical scheme is first applied to a perfectly-triangular 2D wedge. It is shown that the 2D critical slope αc for stability is captured precisely by the numerical scheme, the ramp and the back thrust corresponding to regions of localized virtual strain. The influence of the back-wall friction on αc is explored, explained by the Mohr construction and by analogue experiments with sand. The first 3D problem concerns a wedge with a lateral variation in its topographic slope α so that it is sub-critical (α < αc) and super-critical (α > αc) to the right and to the left boundary, respectively. It is shown that the localized deformation of the ramp on the right side, is getting diffuse as one moves to the left side where more décollement is activated. The influence of the two lateral boundaries is felt for wedge widths even greater than the length. The second 3D problem explores the influence of the side wall friction on the results of laboratory experiments. It is found that the deformation is diffuse close to the side wall with a vertical stretching and less dcollement activated. The side wall influences the rest of the wedge over a width 1.5 times the wedge thickness, for realistic friction angles. Comparison with analogue experiments shows the connection between the virtual 3D velocity field and the actual deformation.

  17. Insights on deep, accretionary subduction processes from the Sistan ophiolitic "mélange" (Eastern Iran)

    NASA Astrophysics Data System (ADS)

    Angiboust, S.; Agard, P.; De Hoog, J. C. M.; Omrani, J.; Plunder, A.

    2013-01-01

    The Sistan ophiolitic belt, formed by the closure of the N-S trending Sistan Ocean during late Cretaceous times, comprises several branches and basins across a 100 × 700 km area along the Iran-Afghanistan border. One of these, the Ratuk complex, exposes disrupted HP ophiolitic blocks from a paleo-subduction complex generally interpreted as a tectonic "mélange". In order to better understand its overall structure and evaluate the degree of mixing within this mélange, an extensive set of serpentinized peridotites, mafic rocks and metasediments was collected in the Sulabest area (Ratuk complex). A detailed geological and structural map of the Sulabest area is herein provided, in which three main units (the Western, Upper and Eclogitic Units) separated by relatively sharp tectonic contacts were identified. The latter two of these slices exhibit metamorphic evidence for burial along the same HP-LT gradient (up to blueschist and eclogite facies, respectively). Sharp differences in peak metamorphic conditions and retrograde parageneses nevertheless suggest that they followed two distinct P-T trajectories. Geochemical signatures of ultramafic rocks indicate an abyssal origin for the non-metamorphic Western Unit while the presence of mantle wedge serpentinites is inferred for some samples from the high-pressure units. The differences in peak temperatures (between 520 and 650 °C) and the geochemical heterogeneity of mafic rocks suggest that tectonic mixing occurred (only) within the high-pressure units, possibly within the hydrated mantle wedge. Our results show that this portion of the Sistan ophiolitic belt did not form, as earlier proposed, by chaotic tectonic "mélange" (i.e. where small tectonic blocks with distinct P-T histories are mixed in a mechanically weak matrix). We instead propose that this segment of the ophiolitic belt formed via accretionary processes deep in the subduction zone, whereby distinct slices with different P-T histories were tectonically

  18. Headless submarine canyons and fluid flow on the toe of the Cascadia accretionary complex

    USGS Publications Warehouse

    Orange, D.L.; McAdoo, B.G.; Moore, J.C.; Tobin, H.; Screaton, E.; Chezar, H.; Lee, H.; Reid, M.; Vail, R.

    1997-01-01

    Headless submarine canyons with steep headwalls and shallowly sloping floors occur on both the second and third landward vergent anticlines on the toe of the Cascadia accretionary complex off central Oregon (45 ??N, 125?? 30??W). In September 1993, we carried out a series of nine deep tow camera sled runs and nine ALVIN dives to examine the relationship between fluid venting, structure and canyon formation. We studied four canyons on the second and third landward vergent anticlines, as well as the apparently unfailed intercanyon regions along strike. All evidence of fluid expulsion is associated with the canyons; we found no evidence of fluid flow between canyons. Even though all fluid seeps are related to canyons, we did not find seeps in all canyons, and the location of the seeps within the canyons differed. On the landward facing limb of the second landward vergent anticline a robust cold seep community occurs at the canyon's inflection point. This seep is characterized by chemosynthetic vent clams, tube worms and extensive authigenic carbonate. Fluids for this seep may utilize high-permeability flow paths either parallel to bedding within the second thrust ridge or along the underlying thrust fault before leaking into the overriding section. Two seaward facing canyons on the third anticlinal ridge have vent clam communities near the canyon mouths at approximately the intersection between the anticlinal ridge and the adjacent forearc basin. No seeps were found along strike at the intersection of the slope basin and anticlinal ridge. We infer that the lack of seepage along strike and the presence of seeps in canyons may be related to fluid flow below the forearc basin/slope unconformity (overpressured by the impinging thrust fault to the west?) directed toward canyons at the surface.

  19. Sorptivity of fly ash concretes

    SciTech Connect

    Gopalan, M.K.

    1996-08-01

    A factorial experiment was designed to measure the sorptivity of cement and fly ash concretes in order to compare the durability of fly ash concrete against the cement concrete. Sorptivity measurements based on the capillary movement of water was made on three grades of cement concrete and six grades of fly ash mixes. The effect of curing was also studied by treating the samples in two curving conditions. A functional relationship of sorptivity against the strength, curing condition and fly ash content has been presented. The results were useful to analyze the factors influencing the durability of cement and fly ash concretes and to explain why some of the previously reported findings were contradictory. Curing conditions have been found to be the most important factor that affected the durability properties of fly ash concrete. When proper curing was provided, a mix with 40% fly ash was found to reduce the sorptivity by 37%. Under inadequate curing the sorptivity was found to increase by 60%. The influence of curing on cement concrete was found to be of much less importance.

  20. Comparison between MSW ash and RDF ash from incineration process

    SciTech Connect

    Chang, Ni-Bin; Wang, H.P.; Lin, K.S.

    1997-12-01

    Resource recovery plants with waste sorting process prior to incineration have not been successfully developed in many developing countries. The reuse potential of incineration ash in light of toxicity and compressive strength remains unclear due to the inhomogeneous composition and higher moisture content of solid waste in Taiwan. A comparative evaluation of the ash generated from two types of incineration processes were performed in this paper. The results indicate that fly ash collected from both types of incineration processes are classified as hazardous materials because of higher metal contents. The reuse of bottom ash collected from refuse-derived fuel incineration process as fine aggregate in concrete mixing would present 23% lower compressive strength as compared with the normal condition.

  1. Landfilling ash/sludge mixtures

    SciTech Connect

    Benoit, J.; Eighmy, T.T.; Crannell, B.S.

    1999-10-01

    The geotechnical properties of a mixture of municipal solid waste incinerator bottom ash and municipal wastewater treatment plant sludge was investigated for a proposed ash/sludge secure landfill. The components as well as mixtures ranging from 10:1 to 5:1 (ash:sludge, by volume) were evaluated, where appropriate, for a number of geotechnical index and mechanical properties including particle size, water content, specific gravity, density-moisture relationships, shear strength, and compressibility. The results from a compactibility study and stability analysis of the proposed landfill were used to help approve a landfill codisposal concept; a full-scale facility was constructed and is currently operating successfully.

  2. Modifiers of the ash properties

    NASA Astrophysics Data System (ADS)

    Peer, Vaclav; Najser, Jan; Pilat, Peter

    2014-08-01

    The aim of this article is to perform an experimental verification of the impact of added substances to limit or prevent sintering of solid fuel ash, which is formed during the thermochemical conversion of fuels. As a modifiers of ash sintering and melting temperature were used halloysite (aluminosilicate) and limestone, which has similar mechanism of action. Both of them act on the principle of a strong chemical adsorption of potassium ions, which largely cause a reduction of ash fusibility. Influence of the modifiers was observed after tests provided at 900, 1000, 1100 and 1200°C. Modifiers were dosed in amounts of 2, 5 and 10 wt.%.

  3. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  4. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Ash pans. 230.69 Section 230.69 Transportation... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans § 230.69 Ash pans. Ash pans shall be securely supported from mud-rings or frames with no part less than...

  5. Impactites related to atmospheric effects on the surface of Mars: Evidence from Lonar Crater, India and Henbury, Australia

    NASA Astrophysics Data System (ADS)

    Beal, R.; Newsom, H. E.; Wright, S. P.

    2011-12-01

    The surface of Mars has been exposed to impact cratering processes for billions of years and massive megabreccia deposits have been observed in many craters. However, the materials caught up in the hot plume in the atmosphere above the crater should be present in surficial ejecta, but have not been identified by the martian rovers. These materials can include shocked ejecta, impact melts and accretionary lapilli. The effects of melting of the surface due to impinging airbursts from projectiles that breakup in the atmosphere might also be present (Newsom et al., 2010). The erosional effects of wind and water have probably erased much of this evidence from all but more recent craters, but the evidence from terrestrial craters suggests that these features should exist. The Henbury, Australia crater field (largest crater 157m diameter) contains Ni-bearing impactites (confirmed by analysis of ~30 samples by portable XRF) that are hard to explain by any mechanism other than breakup of the iron-meteorite high in the atmosphere and impingement of this Fe-bearing high-temperature gas onto the surface. The Lonar crater in Maharashtra, India (1.8 km diameter) was emplaced in Deccan basalt. The basaltic nature of Lonar crater and its well preserved ejecta blanket makes it an important Mars analog. We have discovered impact melt particles coated in fine grained material and melt fragments in the ejecta at Lonar that suggests that significant welding of material took place within the initial ejecta plume. Although impact melt spherules have been previously observed in Lonar ejecta, we have recently identified two new classes of sub-millimeter (avg size 900 μm) particles. These particles display a layering of fine-grain material and are similar to lapilli at volcanic as well as at other impact craters. Accretionary lapilli are spheroidal ash aggregates deposited either in discrete layers or enclosed in a matrix of fine-grain ash that exhibit a target nucleus interpreted to be

  6. A unified model for gold mineralisation in accretionary orogens and implications for regional-scale exploration targeting methods

    NASA Astrophysics Data System (ADS)

    Hronsky, Jon M. A.; Groves, David I.; Loucks, Robert R.; Begg, Graham C.

    2012-04-01

    Accretionary orogens are the sites of long-lived convergent margin tectonics, both compressional and extensional. They are also the hosts to the majority of the world's important gold deposits. A very diverse range of deposit types occurs within accretionary orogens, commonly in close proximity in space and time to each other. These include porphyry and associated high-sulphidation Au-Cu-Ag deposits, classic low-sulphidation Au-Ag deposits, low-sulphidation Au deposits centred on alkalic intrusive complexes, Carlin-type Au deposits, Au-rich volcanic-hosted massive sulphide deposits, orogenic Au deposits, intrusion-related Au deposits and iron oxide Cu-Au deposits. Empirical patterns of spatial distribution of these deposits suggest there must be fundamental generic controls on gold metallogeny. Various lines of evidence lead to the proposal that the underlying key generic factor controlling accretionary orogen gold metallogeny is regional-scale, long-term, pre- and syn-subduction heterogeneous fertilisation of the lithospheric mantle that becomes a source of mineralisation-associated arc magma or hydrothermal fluid components. This process provides a gold-enriched reservoir that can be accessed later in a diverse range of tectonomagmatic settings. Based on this concept, a unified model is proposed in which the formation of a major gold deposit of any type requires the conjunction in time and space of three essential factors: a fertile upper-mantle source region, a favourable transient remobilisation event, and favourable lithospheric-scale plumbing structure. This framework provides the basis for a practical regional-scale targeting methodology that is applicable to data-poor regions.

  7. Ash Stabilization Campaign Blend Plan

    SciTech Connect

    Winstead, M.L.

    1995-06-21

    This Stabilization Blend Plan documents the material to be processed and the processing order for the FY95 Ash Stabilization Campaign. The primary mission of this process is to reduce the inventory of unstable plutonium bearing ash. The source of the ash is from Rocky Flats and the 232-Z incinerator at the Plutonium Finishing Plant (PFP). The ash is currently being stored in Room 235B and Vault 174 in building 234-5Z. The sludge is to be thermally stabilized in a glovebox in room 230A of the 234-5Z building and material handling for the process will be done in room 230B of the same building. The campaign is scheduled for approximately 12--16 weeks. A total of roughly 4 kg of Pu will be processed.

  8. Consolidation patterns during initiation and evolution of a plate-boundary decollement zone: northern Barbados accretionary prism

    USGS Publications Warehouse

    Moore, J.C.; Klaus, A.; Bangs, N.L.; Bekins, B.; Bucker, C.J.; Bruckmann, W.; Erickson, S.N.; Hansen, O.; Horton, T.; Ireland, P.; Major, C.O.; Moore, G.F.; Peacock, S.; Saito, S.; Screaton, E.J.; Shimeld, J.W.; Stauffer, P.H.; Taymaz, T.; Teas, P.A.; Tokunaga, T.

    1998-01-01

    Borehole logs from the northern Barbados accretionary prism show that the plate-boundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates, but in a patchy manner. The logs calibrate a three-dimensional seismic reflection image of the decollement zone and indicate which portions are of low density and enriched in fluid, and which portions have consolidated. The seismic image demonstrates that an underconsolidated patch of the decollement zone connects to a fluid-rich conduit extending down the decollement surface. Fluid migration up this conduit probably supports the open pore structure in the underconsolidated patch.

  9. Long duration ash probe

    DOEpatents

    Hurley, J.P.; McCollor, D.P.; Selle, S.J.

    1994-07-26

    A long duration ash probe includes a pressure shell connected to a port in a combustor with a sample coupon mounted on a retractable carriage so as to retract the sample coupon within the pressure shell during soot blowing operation of the combustor. A valve mounted at the forward end of the pressure shell is selectively closeable to seal the sample coupon within the shell, and a heating element in the shell is operable to maintain the desired temperature of the sample coupon while retracted within the shell. The carriage is operably mounted on a pair of rails within the shell for longitudinal movement within the shell. A hollow carrier tube connects the hollow cylindrical sample coupon to the carriage, and extends through the carriage and out the rearward end thereof. Air lines are connected to the rearward end of the carrier tube and are operable to permit coolant to pass through the air lines and thence through the carrier tube to the sample coupon so as to cool the sample coupon. 8 figs.

  10. Long duration ash probe

    DOEpatents

    Hurley, John P.; McCollor, Don P.; Selle, Stanley J.

    1994-01-01

    A long duration ash probe includes a pressure shell connected to a port in a combustor with a sample coupon mounted on a retractable carriage so as to retract the sample coupon within the pressure shell during sootblowing operation of the combustor. A valve mounted at the forward end of the pressure shell is selectively closeable to seal the sample coupon within the shell, and a heating element in the shell is operable to maintain the desired temperature of the sample coupon while retracted within the shell. The carriage is operably mounted on a pair of rails within the shell for longitudinal movement within the shell. A hollow carrier tube connects the hollow cylindrical sample coupon to the carriage, and extends through the carriage and out the rearward end thereof. Air lines are connected to the rearward end of the carrier tube and are operable to permit coolant to pass through the air lines and thence through the carrier tube to the sample coupon so as to cool the sample coupon.

  11. The Calm Before the Storm: Exploring the Post Accretionary Doldrums Prior to the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Bottke, W. F., Jr.

    2015-12-01

    The early bombardment of the inner solar system played a critical role in planetary evolution, but there is still considerable uncertainty about what happened when. Dynamical models suggest two major bombardment phases may have taken place: (i) a post-accretionary period where newly-formed worlds were struck by leftover planetesimals, and (ii) a late heavy bombardment period, possibly produced by conditions related to a violent reshuffling of the planets ~4.1-4.2 Gyr ago (Ga). If valid, a relative impact lull took place between the two bombardment phases. We explore the evidence for such doldrums in this talk. Consider: a) Mars. Geochemical and meteorite evidence indicates the giant 10,600 × 8,500 km Borealis basin formed > 4.5 Ga. Many postulated basins forming afterwards, however, can be ruled out by the surprisingly pristine nature of the Borealis boundary in topography and gravity. Three of the four largest remaining basins, Hellas, Isidis, and Argyre, have superposed craters counts indicating they are < 4.1 Ga. b) Asteroids. The oldest and most extensive sets of 39Ar-40Ar shock degassing ages, found within meteorites that were heavily shocked, shock-melted, or otherwise showed some evidence for having been part of a large collision, show age clusters between ~3.5-4.1 Ga and ~4.4-4.54 Ga. Using dynamical/impact heating models, it can be argued that relatively few projectiles were on planet-crossing orbits between ~4.1-4.4 Ga. c) Moon. The Moon is probably 4.47 Ga, yet most sample evidence for basin-sized impacts may be < 4.2 Ga. The age gap is curious unless many basins were created close in time to the solidification of the lunar crust. Using collisional/dynamical models, it can be shown that many early basins and craters formed > 4.4 Ga. Here the early impactors may be surviving debris from the Moon-forming giant impact event; note that ejecta initially escaping the Earth-Moon system can come back over many tens of Myr. This would leave doldrums between ~4

  12. Results from SCS Profiling of the Sumatra accretionary prism: insights into tsnamigenesis

    NASA Astrophysics Data System (ADS)

    Fisher, D.; Mosher, D.; Austin, J.; Gulick, S.; Moran, K.; Masterlark, T.

    2007-12-01

    The SEATOS high resolution single-channel seismic reflection survey of the Sumatran accretionary prism depicts a landward-vergent thrust front, with active folding characterizing part of the December 2004 Mw9.2 earthquake rupture zone. Structure and bathymetry co-vary at distinct wavelengths along a 220-km-long profile crossing the prism and the Aceh (forearc) Basin. At the largest wavelength (tens of kms), the prism surface is defined by a steep (8-12 degrees), 55-km-wide outer slope, a 110-km-wide upper slope forming a broad depression between two forearc highs, and a 25 km-wide, steep inner slope between the landward high and the forearc basin. Anticlinal ridges spaced ~13 km apart display landward- and seaward-vergent folds along the inner and outer slopes, respectively; symmetric folding occurs across the upper slope. We suggest that the long-wavelength variations are consistent with the existence of a strong inner wedge beneath the upper slope. The ~13 km anticline spacing implies deformation of a slope apron deforming independently of this stronger wedge interior. Seismic profiles crossing the toe of the prism image a series of landward vergent, fault-related folds, suggesting that the shallow fill of the Sunda Trench is delaminated from the predominantly seaward-vergent plate boundary system and is uptilted along a triangle zone. Profiles crossing the seaward flank of the Aceh Basin reveal a near- vertical, undulatory deformation front that appears to mark the location of the West Andaman-Mentawai right- lateral strike-slip fault zone. Our model for prism architecture based on these geophysical results involves advance of the strong inner wedge during great earthquakes like the 2004 event, which then peels up shallower and less competent trench fill, deforming the toe and the upper slope of the forearc, producing massive uplift that is likely tsunamigenic. Seismic rupture was limited to the megathrust westward of the West Andaman fault and ROV observations

  13. Mud volcano venting induced gas hydrate formation at the upper slope accretionary wedge, offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Saulwood; Tseng, Yi-Ting; Cheng, Wan-Yen; Chou, Cheng-Tien; Chen, NeiChen; Hsieh, I.-Chih

    2016-04-01

    TsanYao Mud Volcano (TYMV) is the largest mud volcano cone in the Hengchun Mud Volcano Group (HCMVG), located at the upper slope of the accrretionary wedge, southwest of Taiwan. The region is under active tectonic activity with the Philippine Plate, moving northwestward at a rate of ~8 cm/year. This region also receives huge quantity of suspended particle load of ~100 mT/year at present time from adjacent small rivers of the Island of Taiwan. Large loads of suspended sediments influx become a major source of organic carbon and later gas and other hydrocarbon. Gas and fluid in the mud volcano are actively venting from deep to the sea floor on the upper slope of the accretionary wedge. In order to understand venting on the HCMVG, echo sounder, towcam and coring were carried out. Pore water sulfate, chloride, potassium, calcium, stable isotope O-18, gas compositions, dissolved sulfide were analysed. The HCMVG consists of 12 volcano cones of different sizes. Large quantity of gas and fluid are venting directly from deep to the TYMV structure high, as well as 50+ other vents as appeared as flares on the echo sounder. Some flares are reaching to the atmosphere and likely a source of green house gases to the atmosphere. Venting fluids include gas bubbles, suspended particle, mud, and breccia. Breccia size could reach more than 12 cm in diameter. Circular bands in different color appeared around the cone may represent stages of vent eruptions. Compositions of vent gas include methane, ethane and propane. High proportions of ethane and propane in the vent gas demonstrated that source of gas are thermogenic in origin. Patchy authigenic carbonate, bacterial mats, bivalves, tube worms and other chemosynthesis organisms were supported by venting gas AOM process near the sea floor. Pore water chloride concentrations show distinct variation pattern from center cone to the side of the volcano, with low in the center and high away from the cone. Pore water with higher than seawater

  14. Observations and Rock Analyses in a Kumano Mud Volcano in Nankai Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Morita, S.; Aoike, K.; Sawada, T.; Ashi, J.; Gulick, S. P.; Flemings, P. B.; Kuramoto, S.; Saito, S.; Mikada, H.; Kinoshita, M.

    2002-12-01

    Kumano Basin is a forearc basin on the eastern Nankai Accretionary Prism off southwest Japan. Recent bathymetric survey showed existence of small knolls in the Kumano Basin. Submersible and ROV dives, sidescan sonar and deep-towed camera investigations revealed so far that at least five of the small knolls are mud volcanoes erupted on the Kumano Basin floor. In June and August, 2002, Dive 677 and 681 by submersible SHINKAI 6500 (YK02-02: R/V Yokosuka) and Dive 267 by ROV KAIKO (KR02-10: R/V Kairei) were performed in one of the mud volcanoes, Kumano Knoll No.4, which is 100 m high and 800 m in diameter at the foot of the knoll. The knoll has a plateau of about 300 m diameter on the top, which shows bumpy surface where there are waves, steps and craters of several meters in diameter. The craters imply active or dead cold seeps and are occasionally accompanied by Calyptogena colonies. The plateau is mostly covered with mud. Rock gravels and boulders were observed mainly on outer slope of the knoll. Sidescan sonar and subbottom profiler data by KAIKO system show marked contrasts in sonic reflectivity and penetration between the Kumano Knoll No.4 and the Kumano Basin floor. The high sonic reflectivity and the low penetration on the knoll indicate that main body of the knoll is composed of clastic ejecta as a mud volcano. On the Kumano Knoll No.4, the dives obtained semi-consolidated mudstone, mud breccia, and biotite arkose sandstone. Chronological analysis on nannofossil indicates the sedimentary rocks are in the late Early Miocene through the Middle Miocene. According to this age and geological information on land, it is likely that the sedimentary rocks on the knoll were originally deposited at the beginning of formation of the Kumano Basin. Porosity of these sedimentary rocks is very low (< 18 %). Some mud breccias contain calcite veins that cut the angular mud gravels. These features lead to finding processes until when the sedimentary rocks reached to the seafloor

  15. Seismic slip propagation along a fault in the Shimanto accretionary prism detected by vitrinite reflectance studies

    NASA Astrophysics Data System (ADS)

    Kitamura, M.; Mukoyoshi, H.; Hirose, T.

    2011-12-01

    Quantitative assessment of heat generation along faults during fault movement is of primary importance in understanding the dynamics of earthquakes. Last several years localized heat anomaly in a fault zone due to rapid seismic sliding has been detected by various analyses of fault zone materials, such as ferromagnetic resonance signal (Fukuchi et al., 2005), trace elements and isotopes (e.g., Ishikawa et al., 2008) and mineralogical change of clay (e.g., Hirono et al., 2008) and vitrinite reflectance (O'Hara, 2004). Here we report a heat anomaly found in a fault zone in the Shimanto accretionary complex by vitrinite reflectance measurements. Mature faults in nature mostly experience multiple seismic events, resulting in integrated heat anomaly. Thus, in addition to vitrinite reflectance measurements across natural faults, we performed high-velocity friction experiments on a mixture of quartz and vitrinite grains to evaluate how multiple rapid-slip events affect vitrinite reflectance in a fault zone. A localized heat anomaly is found in one of fault zones which are developed within a mélange unit in the Cretaceous Shimanto belt, SW Japan. A principle slip zone with thickness of ~5 mm forms within cataclastic damage zone with thickness of ~3 m. The slip zone is mainly composed of well-foliated clay minerals. Host rocks are characterized by a block-in-matrix texture: aligned sandstone and chert blocks embedded in mudstone matrix. We measured vitrinite reflectance across the fault zone by the same method as reported in Sakaguchi et al., (2011). The measurement reveals that the principle slip zone underwent localized temperature of more than 220°C, while background temperature of both damage zone and host rocks is ~170°C. Since fault motion along most active faults occurs seismological, that inevitably generates frictional heat, the localized heat anomaly is possibly caused by the rapid seismic slip. In order to evaluate the change in vitrinite reflectance by

  16. Identification and Analysis of Methane Plumes from the Barbados Accretionary Complex Identified in Multibeam Sonar Data

    NASA Astrophysics Data System (ADS)

    Barnard, A.; Casey, J.

    2013-12-01

    Integration of modern high-resolution multibeam deliverables can relate water column features to seafloor geologic structures. As well as providing coverage of wide areas, the data can also be used to infer volume and variability of gas seeps and characterize the spatial relationships with seafloor features. As part of cruise AT21-02 to the Barbados Accretionary Complex a ~12 kHz Kongsberg EM122 hull-mounted multibeam system was deployed. We processed the multibeam data using the QPS modules to produce a subsea 4D multi-resolution scene files containing bathymetry, acoustic backscatter and midwater data. Within the scene we have identified a region of giant mud volcanoes and a second region along strike containing several ~1000 m tall flares in the water column data directly above cratered hummocky seafloor with high amplitude backscatter at ~-1500 m water depth that are interpreted as ebullition craters beneath gas plumes. From the acoustic returns we relate the bubble diameter or volume to the received signal strength. Evidence exists for armoring of the gas bubbles in the water column by hydrate: the modeled gas hydrate stability zone reaches ~600 m above the seafloor but the acoustic resolution of our dataset is similar to the maximum depth of disappearance of the bubble plume. The shear observed in the rising gas plume may be the result of transport in the current direction of the lowest water mass from the northwest to southeast at 128°, a direction similar to the transport direction of the lowest water mass in this region, or the presence of abyssal undular vortices. Seismic data from this area has bottom simulating reflectors indicating the presence of methane hydrate and it is likely that the observed flares are related to dissociation of methane in the subsurface. The release of gasses may be related to changes in the thickness of the gas hydrate stability zone in the underlying sediments responding to temperature changes in the lowest water mass. To

  17. Physical properties of the Nankai inner accretionary prism sediments at Site C0002, IODP Expedition 348.

    NASA Astrophysics Data System (ADS)

    Kitamura, M.; Kitajima, H.; Henry, P.; Valdez, R. D., II; Josh, M.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

    2014-12-01

    Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Expedition 348 focused on deepening the existing riser hole at Site C0002 to ~3000 meters below seafloor (mbsf) to access the deep interior of the Miocene inner accretionary prism. This unique tectonic environment, which has never before been sampled in situ by ocean drilling, was characterized through riser drilling, logging while drilling (LWD), mud gas monitoring and sampling, and cuttings and core analysis. Shipboard physical properties measurements including moisture and density (MAD), electrical conductivity, P-wave, natural gamma ray, and magnetic susceptibility measurements were performed mainly on cuttings samples from 870.5 to 3058.5 mbsf, but also on core samples from 2163 and 2204 mbsf. MAD measurements were conducted on seawater-washed cuttings ("bulk cuttings") in two size fractions of >4 mm and 1-4 mm from 870.5 to 3058.5 mbsf, and hand-picked intact cuttings from the >4 mm size fractions within 1222.5-3058.5 mbsf interval. The bulk cuttings show grain density of ~2.7 g/cm3, bulk density of 1.9 g/cm3 to 2.2 g/cm3, and porosity of 50% to 32%. Compared to the values on bulk cuttings, the intact cuttings show almost the same grain density, but higher bulk density and lower porosity, respectively. Combined with the MAD measurements on hand-picked intact cuttings and discrete core samples from previous expeditions, porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf at Site C0002. Electrical conductivity and P-wave velocity on discrete samples, which were prepared from both cuttings and core samples in the depth interval of 1745.5-3058.5 mbsf, range 0.15-0.9 S/m and 1.7-4.5 km/s, respectively. The electrical resistivity on discrete samples is higher than the LWD resistivity data but the overall depth trends are similar. The electrical conductivity and P-wave velocity on discrete samples corrected for in-situ pressure and temperature

  18. Fluid circulation in the depths of accretionary prisms: an example of the Shimanto Belt, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Raimbourg, Hugues; Vacelet, Maxime; Ramboz, Claire; Famin, Vincent; Augier, Romain; Palazzin, Giulia; Yamaguchi, Asuka; Kimura, Gaku

    2015-08-01

    Accretionary prisms constitute ideal targets to study fluid circulation and fluid-rock interactions at depths beyond the reach of active margin deep drilling. The highest-grade rocks from the Shimanto Belt on Kyushu were buried under 3-5 kbars at ~ 300°C (Toriumi and Teruya, 1988). They contain abundant quartz veins, formed throughout burial and exhumation and variably affected by brittle and ductile deformation. Cathodoluminescence (CL) reveals the existence of two distinct types of quartz, characterized by a blue and brown color, respectively. CL-blue quartz fills macro-veins (width ≥ 10μm), while CL-brown quartz is present in micro-veins (width ~ 1 - 10μm) and ductilely recrystallized domains. On the basis of microstructures, the fluids associated with the CL-blue and CL-brown quartz are interpreted as "external" and "local", respectively. Quartz growth rims of alternating CL colors as well as mutually cross-cutting veins show that the two fluids cyclically wetted the host rock. From fluid inclusions analysis, the fluid associated with CL-blue quartz has a salinity similar to seawater, while the fluid associated with CL-brown quartz is less saline. In addition, CL-blue quartz is richer in aluminum than the CL-brown one. In contrast to the salinity/aluminum signature, the δ18O isotopic signature of both quartz types is similar and buffered by host rock. The difference between the preservation of the salinity signature of the fluid and the loss of its δ18O signature is explained by quicker exchange kinetics and larger host rock buffering capacity for isotopic reequilibration. The "local" fluid, associated with CL-brown quartz, reflects the dilution of pore water by the pure water produced by prograde dehydration reactions of clay minerals. The "external" fluid associated with CL-blue quartz is interpreted as seawater or pore water from shallow (depth < 1-2 km below seafloor) sediments. We propose that downward percolation of shallow water to depths ~ 10 km

  19. Geophysical evidence of mud diapirism on the Mediterranean Ridge accretionary complex

    NASA Astrophysics Data System (ADS)

    Camerlenghi, A.; Cita, M. B.; Della Vedova, B.; Fusi, N.; Mirabile, L.; Pellis, G.

    1995-04-01

    Mud volcanoes, mud cones, and mud ridges have been identified on the inner portion of the crestal area, and possibly on the inner escarpment, of the Mediterranean Ridge accretionary complex. Four areas containing one or more mud diapirs have been investigated through bathymetric profiling, single channel seismic reflection profiling, heat flow measurements, and coring. A sequence of events is identified in the evolution of the mud diapirs: initially the expulsion on the seafloor of gasrich mud produces a seafloor depression outlined in the seismic record by downward dip of the host sediment reflectors towards the mud conduit; subsequent eruptions of fluid mud may create a flat topped mud volcano with step-like profile; finally, the intrusion of viscous mud produces a mud cone. The origin of the diapirs is deep within the Mediterranean Ridge. Although a minimum depth of about 400 m below the seafloor has been computed from the hydrostatic balance between the diapiric sediments and the host sediments, a maximum depth, suggested by geometric considerations, ranges between 5.3 and 7 km. The presence of thermogenic gas in the diapiric sediments suggests a better constrained origin depth of at least 2.2 km. The heat flow measured within the Olimpi mud diapir field and along a transect orthogonal to the diapiric field is low, ranging between 16 ± 5 and 41 ± 6 mW m-2. Due to the presence of gas, the thermal conductivity of the diapiric sediments is lower than that of the host hemipelagic oozes (0.6 0.9 and 1.0 1.15 W m-1 K-1 respectively). We consider the distribution of mud diapirs to be controlled by the presence of tectonic features such as reverse faults or thrusts (inner escarpment) that develop where the thickness of the Late Miocene evaporites appears to be minimum. An upward migration through time of the position of the décollement within the stratigraphic column from the Upper Oligocene (diapiric sediments) to the Upper Miocene (present position) is identified.

  20. Origin and evolution of fluids from mud volcanoes in the Barbados accretionary complex

    NASA Astrophysics Data System (ADS)

    Godon, Arnaud; Jendrzejewski, Nathalie; Castrec-Rouelle, Maryse; Dia, Aline; Pineau, Françoise; Boulègue, Jacques; Javoy, Marc

    2004-05-01

    A large collection of fluids (54 interstitial fluids and four expelled fluids) were sampled at the Manon site, at the outer edge of the Barbados accretionary complex. These warm fluids (up to 20°C) are expelled by sub-marine (5000 mbsl) mud volcanoes consisting of diapirs (unchanneled flow) and diatremes (channeled). Chlorine stable isotope ratios of these fluids were measured by IRMS with a reproducibility of ± 0.05‰ (1σ) versus SMOC (Standard Mean Ocean Chloride). A large range of δ 37Cl between -5.3‰ and +0.1‰ is observed. Data from each volcanic structure describe a mixing between seawater and a low-δ 37Cl fluid. The whole set of data is interpreted as the result of a mixing between two deep components and seawater. The two deep fluids are chemically distinct (e.g., in Ca, Mg, K, Li, Sr and Br contents and Br/Cl ratio). They display low and significantly different 87Sr/ 86Sr ratios (0.707790 and 0.707892, respectively) and δ 37Cl values (-4.51 and -5.24‰, respectively). Physicochemical processes such as mineralogical transformation, diffusion, compaction or ion filtration are known to fractionate chlorine stable isotopes and can produce fluids with negative δ 37Cl values. Ion filtration due to sediment compaction appears to be the more likely process to explain the negative δ 37Cl values observed at the Manon site. A model for the generation of these signatures is proposed where a residual negative δ 37Cl fluid reservoir is created at the bottom of the prism or the sediment pile. Further compaction/fracturing and/or dewatering of the slab may flush out these fluids and focus them towards the décollement zone. Mixing between the fluids and ultimately with seawater and water released during gas hydrate destabilizations may explain the data set within the individual cores and between the different structures.

  1. The 2005 and 2010 dome collapse driven block and ash flows on Shiveluch volcano, Kamchatka: Morphological analysis using satellite- and field-based data

    NASA Astrophysics Data System (ADS)

    Krippner, J.; Belousov, A.; Belousova, M.; Ramsey, M. S.

    2015-12-01

    A new multi-scale investigation of recent block and ash flow deposits on Shiveluch volcano, Kamchatka, using satellite- and field-based data has produced a detailed description of the surface deposits. In February, 2005 and October, 2010 Shiveluch produced large dome-collapse block and ash flows that travelled more than 19 km down the southern flanks. These deposits have now been interpreted using high-resolution (~0.5 m) WorldView-02 and QuickBird-02 panchromatic satellite data to describe surficial morphologies, block distributions, forest devastation and the subsequent tree deposition. These data reveal complex deposits composed of overlapping flows and lobes with diverse morphologies including channel and levee structures, varying lobate terminations, compaction features, ridges, small hummock-like features, arcuate scarps, as well as post-depositional erosion and reworking, which were later investigated in the field. The deposits are composed of poorly sorted, porphyritic, dome material which is largely oxidized with rare evidence of hydrothermal alteration, as well as lithics eroded from older deposits, all within an ash-lapilli matrix. Large dome blocks up to 12 m in diameter are deposited to the distal edges of the deposit and are dominantly sub-rounded, and composed of banded, porphyritic, poorly vesicular, variably oxidized dome material with mafic xenolith inclusions. Many of these display fracturing and impact scours. This study links satellite-based interpretations of large block and ash flow deposits to field observations, allowing the remote identification of morphological features. This multi-scale investigation of these morphologies can be applied elsewhere for the rapid and safe identification of fresh deposits in dangerous or remote locations.

  2. Formation of forearc basins by collision between seamounts and accretionary wedges: an example from the New Hebrides subduction zone

    USGS Publications Warehouse

    Collot, J.-Y.; Fisher, M.A.

    1989-01-01

    Seabeam data reveal two deep subcircular reentrants in the lower arc slope of the New Hebrides island arc that may illustrate two stages in the development of a novel type of forearc basin. The Malekula reentrant lies just south of the partly subducted Bougainville seamount. This proximity, as well as the similarity in morphology between the reentrant and an indentation in the lower arc slope off Japan, suggests that the Malekula reentrant formed by the collision of a seamount with the arc. An arcuate fold-thrust belt has formed across the mouth of the reentrant, forming the toe of a new accretionary wedge. The Efate reentrant may show the next stage in basin development. This reentrant lies landward of a lower-slope ridge that may have begun to form as an arcuate fold-thrust belt across the mouth of a reentrant. This belt may have grown by continued accretion at the toe of the wedge, by underplating beneath the reentrant, and by trapping of sediment shed from the island arc. These processes could result in a roughly circular forearc basin. Basins that may have formed by seamount collision lie within the accretionary wedge adjacent to the Aleutian trenches. -Authors

  3. Controlling formaldehyde emissions with boiler ash.

    PubMed

    Cowan, Jennifer; Abu-Daabes, Malyuba; Banerjee, Sujit

    2005-07-01

    Fluidized wood ash reduces formaldehyde in air from about 20 to <1 ppmv. Methanol is removed to a much lower extent. The efficiency of formaldehyde reduction increases with increasing moisture content of the ash. Sorption of formaldehyde to ash can be substantially accounted for by partitioning to the water contained in the ash followed by rate-controlling binding to the ash solids. Adsorption occurs at temperatures of up to 165 degrees C; oxidation predominates thereafter. It is proposed that formaldehyde could be stripped from an air stream in a fluidized bed containing ash, which could then be returned to a boiler to incinerate the formaldehyde.

  4. Ash in fire affected ecosystems

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Jordan, Antonio; Cerda, Artemi; Martin, Deborah

    2015-04-01

    Ash in fire affected ecosystems Ash lefts an important footprint in the ecosystems and has a key role in the immediate period after the fire (Bodi et al., 2014; Pereira et al., 2015). It is an important source of nutrients for plant recover (Pereira et al., 2014a), protects soil from erosion and controls soil hydrological process as runoff, infiltration and water repellency (Cerda and Doerr, 2008; Bodi et al., 2012, Pereira et al., 2014b). Despite the recognition of ash impact and contribution to ecosystems recuperation, it is assumed that we still have little knowledge about the implications of ash in fire affected areas. Regarding this situation we wanted to improve our knowledge in this field and understand the state of the research about fire ash around world. The special issue about "The role of ash in fire affected ecosystems" currently in publication in CATENA born from the necessity of joint efforts, identify research gaps, and discuss future cooperation in this interdisciplinary field. This is the first special issue about fire ash in the international literature. In total it will be published 10 papers focused in different aspects of the impacts of ash in fire affected ecosystems from several parts of the world: • Fire reconstruction using charcoal particles (Burjachs and Espositio, in press) • Ash slurries impact on rheological properties of Runoff (Burns and Gabet, in press) • Methods to analyse ash conductivity and sorbtivity in the laboratory and in the field (Balfour et al., in press) • Termogravimetric and hydrological properties of ash (Dlapa et al. in press) • Effects of ash cover in water infiltration (Leon et al., in press) • Impact of ash in volcanic soils (Dorta Almenar et al., in press; Escuday et al., in press) • Ash PAH and Chemical extracts (Silva et al., in press) • Microbiology (Barreiro et al., in press; Lombao et al., in press) We believe that this special issue will contribute importantly to the better understanding of

  5. Ash in fire affected ecosystems

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Jordan, Antonio; Cerda, Artemi; Martin, Deborah

    2015-04-01

    Ash in fire affected ecosystems Ash lefts an important footprint in the ecosystems and has a key role in the immediate period after the fire (Bodi et al., 2014; Pereira et al., 2015). It is an important source of nutrients for plant recover (Pereira et al., 2014a), protects soil from erosion and controls soil hydrological process as runoff, infiltration and water repellency (Cerda and Doerr, 2008; Bodi et al., 2012, Pereira et al., 2014b). Despite the recognition of ash impact and contribution to ecosystems recuperation, it is assumed that we still have little knowledge about the implications of ash in fire affected areas. Regarding this situation we wanted to improve our knowledge in this field and understand the state of the research about fire ash around world. The special issue about "The role of ash in fire affected ecosystems" currently in publication in CATENA born from the necessity of joint efforts, identify research gaps, and discuss future cooperation in this interdisciplinary field. This is the first special issue about fire ash in the international literature. In total it will be published 10 papers focused in different aspects of the impacts of ash in fire affected ecosystems from several parts of the world: • Fire reconstruction using charcoal particles (Burjachs and Espositio, in press) • Ash slurries impact on rheological properties of Runoff (Burns and Gabet, in press) • Methods to analyse ash conductivity and sorbtivity in the laboratory and in the field (Balfour et al., in press) • Termogravimetric and hydrological properties of ash (Dlapa et al. in press) • Effects of ash cover in water infiltration (Leon et al., in press) • Impact of ash in volcanic soils (Dorta Almenar et al., in press; Escuday et al., in press) • Ash PAH and Chemical extracts (Silva et al., in press) • Microbiology (Barreiro et al., in press; Lombao et al., in press) We believe that this special issue will contribute importantly to the better understanding of

  6. Control of structural inheritance on thrust initiation and material transfer in accretionary wedges

    NASA Astrophysics Data System (ADS)

    Leever, Karen; Geersen, Jacob; Ritter, Malte; Lieser, Kathrin; Behrmann, Jan

    2016-04-01

    Faults in the incoming sediment layer are commonly observed in subduction zone settings and well developed in the incoming plate off Sumatra. To investigate how they affect the structural development of the accretionary wedge, we conducted a series of 2D analogue tectonic experiments in which a 2 cm thick quartz sand layer on top of a thin detachment layer of glass beads was pulled against a rigid backstop by a basal conveyor belt in a 20cm wide box with glass walls. A gap at the base of the back wall avoids entrainment of the glass beads. At regular spacing of either 2.3, 5.5 or 7.8 cm (fractions of the thrust sheet length in the reference model), conjugate pairs of weakness zones dipping 60deg were created by cutting the sand layer with a thin (1 mm) metal blade. Both the undisturbed sand and the pre-cuts have an angle of internal friction of ~29o, but their cohesion is different by 50 Pa (110 Pa for the undisturbed material, 60 Pa along the pre-cuts). Friction of the glass beads is ~24deg. The experiments are monitored with high resolution digital cameras; displacement fields derived from digital image correlation are used to constrain fault activity. In all experiments, a critically tapered wedge developed with a surface slope of 7.5deg. In the reference model (no weakness zones in the input section), the position of new thrust faults is controlled by the frontal slope break. The average length of the thrust sheets is 11 cm and the individual thrusts accommodate on average 8 cm displacement each. The presence of weakness zones causes thrust initiation at a position different from the reference case, and affects their dip. For a fault spacing of 7.8 cm (or 75% of the reference thrust sheet length), every single incoming weakness zone causes the formation of a new thrust, thus resulting in thrust sheets shorter than the equilibrium case. In addition, less displacement is accommodated on each thrust. As a consequence, the frontal taper is smaller than expected

  7. Physical properties of the Nankai inner accretionary prism at Site C0002, IODP Expedition 348

    NASA Astrophysics Data System (ADS)

    Kitamura, Manami; Kitajima, Hiroko; Henry, Pierre; Valdez, Robert; Josh, Matthew

    2014-05-01

    Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Expedition 348 focused on deepening the existing riser hole at Site C0002 to ~3000 meters below seafloor (mbsf) to access the deep interior of the Miocene inner accretionary prism. This unique tectonic environment, which has never before been sampled in situ by ocean drilling, was characterized through riser drilling, logging while drilling (LWD), mud gas monitoring and sampling, and cuttings and core analysis. Shipboard physical properties measurements including moisture and density (MAD), electrical conductivity, P-wave, natural gamma ray, and magnetic susceptibility measurements were performed mainly on cuttings samples from 870.5 to 3058.5 mbsf, but also on core samples from 2163 and 2204 mbsf. MAD measurements were conducted on seawater-washed cuttings ("bulk cuttings") in two size fractions of >4 mm and 1-4 mm from 870.5 to 3058.5 mbsf, and hand-picked intact cuttings from the >4 mm size fractions within 1222.5-3058.5 mbsf interval. The bulk cuttings show grain density of 2.68 g/cm3 and 2.72 g/cm3, bulk density of 1.9 g/cm3 to 2.2 g/cm3, and porosity of 50% to 32%. Compared to the values on bulk cuttings, the intact cuttings show almost the same grain density (2.66-2.70 g/cm3), but higher bulk density (2.05-2.41 g/cm3) and lower porosity (37-18%), respectively. The grain density agreement suggests that the measurements on both bulk cuttings and intact cuttings are of good quality, and the differences in porosity and density are real, but the values from the bulk cuttings are affected strongly by artifacts of the drilling process. Thus, the bulk density and porosity data on handpicked cuttings are better representative of formation properties. Combined with the MAD measurements on hand-picked intact cuttings and discrete core samples from previous expeditions, porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf at Site C0002. Electrical

  8. The Eocimmerian history of Central Iran: the accretionary wedge of Anarak

    NASA Astrophysics Data System (ADS)

    Malaspina, Nadia; Zanchi, Andrea; Berra, Fabrizio; Javadi, Hamid Reza; Koohpeyma, Meysam; Ghassemi, Mohammad R.; Sheikholeslami, Mohammad Reza; Bergomi, Maria; Tunesi, Annalisa; Zanchetta, Stefano

    2013-04-01

    The Anarak region of Central Iran is a key area for the understanding of the Late Palaeozoic to Triassic Cimmerian evolution of Iran. The Anarak Metamorphic Complex (AMC) forms an E-W trending mountain ridge, which separates the Triassic of Nakhlak to the north from a continuous non-metamorphic Palaeozoic to Mesozoic sedimentary succession to the south and was interpreted as an accretionary wedge active from Late Palaeozoic to Triassic times. The AMC is sharply cross-cut westward by the Upper Cretaceous "Coloured Melange", consisting of low- to medium- grade metamorphic rocks with tectonically intercalated slivers of serpentinite often associated to blue schists. The occurrence of this rock association in Central Iran poses several questions regarding its evolution and especially on the number of Cimmerian (Palaeotethys) sutures (single rather than multiple) between Eurasia and Iran. The AMC includes several subunits (Morghab, Chah Gorbeh, Patyar, Palhavand Gneiss, Lakh Marble and Doshak) which differ for composition and/or metamorphic evolution. Based on field observations, the Morghab and Chah Gorbeh units suggest a common deformation and a similar metamorphic history, characterised by three major folding events. The first two events developed pervasive axial plane foliations causing a complete transposition of the primary stratigraphic characters. Folding was accompanied by two main metamorphic events, the latter showing retrogression from possible medium to low grade conditions. During the third folding stage, large-scale plunging to vertical open folds were superposed on previous folds in the area north of the Kuh-e Chah Gorbeh, deforming the previous penetrative foliations. In this frame, the Palhavand Gneiss can be considered as part of the same metamorphic unit which escaped a more pervasive low grade retrogression. Concerning the Patyar unit, previous studies considered the Lakh Marble as the lagoonal sediments of an atoll. Field analyses indicate that the

  9. Mineral resource of the month: soda ash

    USGS Publications Warehouse

    Kostic, Dennis S.

    2006-01-01

    Soda ash, also known as sodium carbonate, is an alkali chemical that can be refined from the mineral trona and from sodium carbonate-bearing brines. Several chemical processes exist for manufacturing synthetic soda ash.

  10. Size and aspect ratio distributions of blocks in a mélange of the Shimanto accretionary complex, southwest Japan

    NASA Astrophysics Data System (ADS)

    Tabuchi, Y.; Tonai, S.

    2015-12-01

    Block-in-matrix fabrics in accretionary complex have variety based on their deformation processes. We report characteristics of blocks in the Hioki mélange, which constitutes part of the youngest (late Oligocene to early Miocene) portion of the Shimanto accretionary complex, Shikoku, southwest Japan. The Hioki mélange is regarded as a tectonic mélange which has formed at a few km depth below the surface (e.g., Hibbard et al., 1993; Underwood et al., 1993). The ample exposure of the mélange in the study area provides a good opportunity to observe detailed structure of the block-in-matrix fabrics. The matrix, which is partly folded, is composed of dark gray shale and some green tuff and dark brown shale. Foliations of the matrix, which are manifested by cleavages, roughly strike ENE-WSW and steeply dip mostly toward the north. Blocks consist mainly of sandstone. The size of blocks ranges from millimeter to meter in length of major axes. These blocks are divided into brecciated, boudinage, and playted types on the basis of their shapes. Each type of blocks can be observed throughout the study area. We measured size and aspect ratio of blocks that are more than 10 cm in length of major axes. The average and standard deviation of the block size are 28.5 cm and 41.0 cm, respectively. The median of the aspect ratio is 2.0. To compare with the characteristics of blocks, we also measured length of the major axis and the aspect ratio for blocks of a sedimentary mélange (the Cretaceous Ukibuchi Formation), which also constitutes part of the Shimanto accretionary complex. The Ukibuchi Formation consists mainly of dark-gray shale matrix containing sandstone blocks. The average and standard deviation of block size are 12.2 cm and 8.6 cm, respectively. The median of aspect ratio is 1.6. Each parameter is lower than those of blocks in the Hioki mélange.

  11. Paleotemperature of the Nankai accretionary prism estimated by vitrinite reflectance of carbonaceous materials retrieved during the IODP Expedition 348

    NASA Astrophysics Data System (ADS)

    Fukuchi, R.; Yamaguchi, A.; Yamamoto, Y.; Ashi, J.

    2015-12-01

    Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Expedition 348 took place from 13 September 2013 to 29 January 2014. During the Exp. 348, cuttings, mud gas, and logging data were collected from Holes C0002N and C0002P down to 3058.5 mbsf. Cores were collected from 2163 to 2218 mbsf of Hole C0002P. Three lithologic units were identified at Site C0002 based on geological and geochemical characteristics of core and cuttings samples: Unit III (875.5-975.5 mbsf in Hole C0002N), Unit IV (975.5-1665.5 mbsf in Hole C0002N), and Unit V (1665.5-2325.5 mbsf in Hole C0002N, and 1965.5-3058.5 mbsf in Hole C0002P) (Tobin et al., 2015). To evaluate whole thermal structure of the Site C0002, we performed vitrinite reflectance analysis for cuttings samples collected every ~100 m, and for borehole core samples collected every ~10 m of Hole C0002N and C0002P. Vitrinite reflectance (Ro) is an indicator to estimate maximum paleotemperature, which has been widely applied to reveal tectonic evolution of on-land accretionary complex in Southwest Japan (e.g. Underwood et al., 1992; Ohomori et al., 1997) and thermal anomalies along fault slip zones reflecting frictional heating due to seismic slip (e.g. Sakaguchi et al., 2011). This is the first study that applied vitrinite analyses systematically to the deep portion of modern accretionary prisms. In this presentation, we report preliminary results of vitrinite reflectance analysis. Ro values are 0.15 to 0.20 in Unit III (forearc basin strata), 0.21 to 0.27 in Unit IV (accretionary prism strata), and 0.26 to 0.38 in Unit V (hemipelagic sediment), respectively. In general, Ro values tend to be gradually and continuously increasing with depth. Estimated paleotemperatures are ~67°C in Unit IV and ~77°C in Unit V. Estimated paleotemperatures are lower than estimated modern temperatures based on borehole temperature measurements and their downward extrapolations (Sugihara et al., 2014). Gaps on

  12. Deformation processes at the down-dip limit of the seismogenic zone: The example of Shimanto accretionary complex

    NASA Astrophysics Data System (ADS)

    Palazzin, G.; Raimbourg, H.; Famin, V.; Jolivet, L.; Kusaba, Y.; Yamaguchi, A.

    2016-09-01

    In order to constrain deformation processes close to the brittle-ductile transition in seismogenic zone, we have carried out a microstructural study in the Shimanto accretionary complex (Japan), the fossil equivalent of modern Nankai accretionary prisms. The Hyuga Tectonic Mélange was sheared along the plate interface at mean temperatures of 245 °C ± 30 °C, as estimated by Raman spectroscopy of carbonaceous material (RSCM). It contains strongly elongated quartz ribbons, characterized by very high fluid inclusions density, as well as micro-veins of quartz. Both fluid inclusion planes and micro-veins are preferentially developed orthogonal to the stretching direction. Furthermore, crystallographic preferred orientation (CPO) of quartz c-axes in the ribbons has maxima parallel to the stretching direction. Recrystallization to a small grain size is restricted to rare deformation bands cutting across the ribbons. In such recrystallized quartz domains, CPO of quartz c-axes are orthogonal to foliation plane. The evolution of deformation micro-processes with increasing temperature can be further analyzed using the Foliated Morotsuka, a slightly higher-grade metamorphic unit (342 ± 30 °C by RSCM) from the Shimanto accretionary complex. In this unit, in contrast to Hyuga Tectonic Mélange, recrystallization of quartz veins is penetrative. CPO of quartz c-axes is concentrated perpendicularly to foliation plane. These variations in microstructures and quartz crystallographic fabric reflect a change in the dominant deformation mechanism with increasing temperatures: above ~ 300 °C, dislocation creep is dominant and results in intense quartz dynamic recrystallization. In contrast, below ~ 300 °C, quartz plasticity is not totally activated and pressure solution is the major deformation process responsible for quartz ribbons growth. In addition, the geometry of the quartz ribbons with respect to the phyllosilicate-rich shear zones shows that bulk rheology is controlled by

  13. Accretionary margin of north-western Hispaniola: morphology, structure and development of part of the northern Caribbean plate boundary

    USGS Publications Warehouse

    Dillon, William P.; Austin, James A.; Scanlon, K.M.; Terence, Edgar N.; Parson, L.M.

    1992-01-01

    Broad-range side-scan sonar (GLORIA) images and single- and multi-channel seismic reflection profiles demonstrate that the margin of north-western Hispaniola has experienced compression as a consequence of oblique North American-Caribbean plate convergence. Two principal morphological or structural types of accretionary wedges are observed along this margin. The first type is characterized by a gently sloping (???4??) sea floor and generally margin-parallel linear sets of sea-floor ridges that gradually deepen towards the flat Hispaniola Basin floor to the north. The ridges are caused by an internal structure consisting of broad anticlines bounded by thrust faults that dip southwards beneath Hispaniola. Anticlines form at the base of the slope and are eventually sheared and underthrust beneath the slope. In contrast, the second type of accretionary wedge exhibits a steeper (???6-16??) sea-floor slope characterized by local slumping and a more abrupt morphological transition to the adjacent basin. The internal structure appears chaotic on seismic reflection profiles and probably consists of tight folds and closely spaced faults. We suggest that changes in sea-floor declivity and internal structure may result from variations in the dip or frictional resistance of the de??collement, or possibly from changes in the cohesive strength of the wedge sediments. The observed pattern of thickening of Hispaniola Basin turbidites towards the insular margin suggests differential southwards tilting of the Hispaniola Basin strata, probably in response to North America-Caribbean plate interactions since the Early Tertiary. Based upon indirect age control from adjacent parts of the northern caribbean plate boundary, we infer a Late Eocene to Early Miocene episode of transcurrent motion (i.e. little or no tilting), an Early Miocene to Late Pliocene period of oblique convergence (i.e. increased tilt) during which the accretionary wedge began to be constructed, and a Late Pliocene to

  14. Plate Tectonics at 3.8-3.7 Ga: Field Evidence from the Isua Accretionary Complex, Southern West Greenland.

    PubMed

    Komiya; Maruyama; Masuda; Nohda; Hayashi; Okamoto

    1999-09-01

    A 1&rcolon;5000 scale mapping was performed in the Isukasia area of the ca. 3.8-Ga Isua supracrustal belt, southern West Greenland. The mapped area is divided into three units bounded by low-angle thrusts: the Northern, Middle, and Southern Units. The Southern Unit, the best exposed, is composed of 14 subunits (horses) with similar lithostratigraphy, bound by layer-parallel thrusts. Duplex structures are widespread in the Isua belt and vary in scale from a few meters to kilometers. Duplexing proceeded from south to north and is well documented in the relationship between link- and roof-thrusts. The reconstructed lithostratigraphy of each horse reveals a simple pattern, in ascending order, of greenstone with low-K tholeiitic composition with or without pillow lava structures, chert/banded iron-formation, and turbidites. The cherts and underlying low-K tholeiites do not contain continent- or arc-derived material. The lithostratigraphy is quite similar to Phanerozoic "oceanic plate stratigraphy," except for the abundance of mafic material in the turbidites. The evidence of duplex structures and oceanic plate stratigraphy indicates that the Isua supracrustal belt is the oldest accretionary complex in the world. The dominantly mafic turbidite composition suggests that the accretionary complex was formed in an intraoceanic environment comparable to the present-day western Pacific Ocean. The duplex polarity suggests that an older accretionary complex should occur to the south of the Isua complex. Moreover, the presence of seawater (documented by a thick, pillow, lava unit at the bottom of oceanic plate stratigraphy) indicates that the surface temperature was less than ca. 100 degrees C in the Early Archean. The oceanic geotherm for the Early Archean lithosphere as a function of age was calculated based on a model of transient half-space cooling at given parameters of surface and mantle temperatures of 100 degrees and 1450 degrees C, respectively, suggesting that the

  15. Deformation processes at the down-dip limit of the seismogenic zone: The example of Shimanto accretionary complex

    NASA Astrophysics Data System (ADS)

    Palazzin, G.; Raimbourg, H.; Famin, V.; Jolivet, L.; Kusaba, Y.; Yamaguchi, A.

    2016-09-01

    In order to constrain deformation processes close to the brittle-ductile transition in seismogenic zone, we have carried out a microstructural study in the Shimanto accretionary complex (Japan), the fossil equivalent of modern Nankai accretionary prisms. The Hyuga Tectonic Mélange was sheared along the plate interface at mean temperatures of 245 °C ± 30 °C, as estimated by Raman spectroscopy of carbonaceous material (RSCM). It contains strongly elongated quartz ribbons, characterized by very high fluid inclusions density, as well as micro-veins of quartz. Both fluid inclusion planes and micro-veins are preferentially developed orthogonal to the stretching direction. Furthermore, crystallographic preferred orientation (CPO) of quartz c-axes in the ribbons has maxima parallel to the stretching direction. Recrystallization to a small grain size is restricted to rare deformation bands cutting across the ribbons. In such recrystallized quartz domains, CPO of quartz c-axes are orthogonal to foliation plane. The evolution of deformation micro-processes with increasing temperature can be further analyzed using the Foliated Morotsuka, a slightly higher-grade metamorphic unit (342 ± 30 °C by RSCM) from the Shimanto accretionary complex. In this unit, in contrast to Hyuga Tectonic Mélange, recrystallization of quartz veins is penetrative. CPO of quartz c-axes is concentrated perpendicularly to foliation plane. These variations in microstructures and quartz crystallographic fabric reflect a change in the dominant deformation mechanism with increasing temperatures: above 300 °C, dislocation creep is dominant and results in intense quartz dynamic recrystallization. In contrast, below 300 °C, quartz plasticity is not totally activated and pressure solution is the major deformation process responsible for quartz ribbons growth. In addition, the geometry of the quartz ribbons with respect to the phyllosilicate-rich shear zones shows that bulk rheology is controlled by

  16. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2011-10-01 2011-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  17. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2012-10-01 2012-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  18. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2014-10-01 2014-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  19. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2013-10-01 2013-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  20. Gasification of high ash, high ash fusion temperature bituminous coals

    DOEpatents

    Liu, Guohai; Vimalchand, Pannalal; Peng, WanWang

    2015-11-13

    This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150.degree. C. to 1500.degree. C. range as well as in excess of 1500.degree. C. In a preferred embodiment, such coals are dealt with a two stage gasification process--a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

  1. Rising from the ashes: Coal ash in recycling and construction

    SciTech Connect

    Naquin, D.

    1998-02-01

    Beneficial Ash Management (BAM, Clearfield, Pa.) has won an environmental award for its use of ash and other waste to fight acid mine drainage. The company`s workers take various waste materials, mainly fly ash from coal-burning plants, to make a cement-like material or grouting, says Ernest Roselli, BAM president. The grouting covers the soil, which helps prevent water from contacting materials. This, in turn, helps control chemical reactions, reducing or eliminating formation of acid mine drainage. The company is restoring the 1,400-acre Bark Camp coal mine site near Penfield in Clearfield County, Pa. Under a no-cost contract with the state of Pennsylvania, BAM is using boiler slag, causticizing byproducts (lime) and nonreclaimable clarifier sludge from International Paper Co. (Erie, Pa.). The mine reclamation techniques developed and monitored at the site include using man-made wetlands to treat acid mine drainage and testing anhydrous ammonia as a similar treatment agent. BAM researches and tests fly ash mixed with lime-based activators as fill material for land reclamation, and develops and uses artificial soil material from paper mill and tannery biosolids.

  2. Transcriptomic Signatures of Ash (Fraxinus spp.) Phloem

    PubMed Central

    Mamidala, Praveen; Bonello, Pierluigi; Herms, Daniel A.; Mittapalli, Omprakash

    2011-01-01

    Background Ash (Fraxinus spp.) is a dominant tree species throughout urban and forested landscapes of North America (NA). The rapid invasion of NA by emerald ash borer (Agrilus planipennis), a wood-boring beetle endemic to Eastern Asia, has resulted in the death of millions of ash trees and threatens billions more. Larvae feed primarily on phloem tissue, which girdles and kills the tree. While NA ash species including black (F. nigra), green (F. pennsylvannica) and white (F. americana) are highly susceptible, the Asian species Manchurian ash (F. mandshurica) is resistant to A. planipennis perhaps due to their co-evolutionary history. Little is known about the molecular genetics of ash. Hence, we undertook a functional genomics approach to identify the repertoire of genes expressed in ash phloem. Methodology and Principal Findings Using 454 pyrosequencing we obtained 58,673 high quality ash sequences from pooled phloem samples of green, white, black, blue and Manchurian ash. Intriguingly, 45% of the deduced proteins were not significantly similar to any sequences in the GenBank non-redundant database. KEGG analysis of the ash sequences revealed a high occurrence of defense related genes. Expression analysis of early regulators potentially involved in plant defense (i.e. transcription factors, calcium dependent protein kinases and a lipoxygenase 3) revealed higher mRNA levels in resistant ash compared to susceptible ash species. Lastly, we predicted a total of 1,272 single nucleotide polymorphisms and 980 microsatellite loci, among which seven microsatellite loci showed polymorphism between different ash species. Conclusions and Significance The current transcriptomic data provide an invaluable resource for understanding the genetic make-up of ash phloem, the target tissue of A. planipennis. These data along with future functional studies could lead to the identification/characterization of defense genes involved in resistance of ash to A. planipennis, and in future

  3. Utilization of fly ash in metallic composites

    SciTech Connect

    Rohatgi, P.K.; Guo, R.Q.; Golden, D.M.

    1996-10-01

    Fly ash particles have been successfully dispersed into aluminum alloy to make aluminum alloy-fly ash composites (Ashalloy) at University of Wisconsin-Milwaukee. Additions of solid and hollow particles of fly ash reduce the cost and density of aluminum castings while increasing their performance. Ashalloy represents a candidate material for high value added use of fly ash, while reducing the disposal volumes of fly ash for the electric utility industry and making the US foundries more competitive. The fly ash particle distribution in the matrix aluminum alloy and the microstructure of aluminum-fly ash composite was determined. Selected properties of cast aluminum-fly ash composites are also presented in this paper. Mechanical properties of aluminum-fly ash composites show that the composite possesses higher hardness and higher elastic modulus compared to the matrix alloy. The flow behavior of molten aluminum-fly ash slurries along with the components cast in aluminum-fly ash composites will be presented. Fly ash containing metal components have potential applications in covers, shrouds, casings, manifolds, valve covers, garden furniture, engine blocks in automotive, small engine and electromechanical industry sector.

  4. Preliminary evaluation of the petroleum potential of the Tertiary accretionary terrane, west side of the Olympic Peninsula, Washington

    SciTech Connect

    Not Available

    1989-01-01

    Convergence between the Pacific and North American plates during late Eocene and late middle Miocene times produced two principal terranes of melange and broken formation (Eocene, Ozette Melange and Miocene, Hoh Melange) exposed onshore along the west side of the Olympic Peninsula. Organic geochemical analyses of 150 samples collected from these two accretionary terranes indicate that they are marginally mature and have a low content of type III organic matter, therefore, they are gas prone rather than oil prone. Geochemical analyses, using molecular markers, indicate that the oil in the Sunshine Mining Co. Medina No. 1 is related to oil extracted from middle Eocene siltstone of the Ozette Melange located as much as 140 km north of the well. The stable carbon and hydrogen isotopic abundance of methane in natural gas seeps and gas in the melange along the west side of the Olympic Peninsula indicate that the gas is mainly thermogenic; however, the relation between these two sources of gas is uncertain.

  5. GPS Velocity Field in Bangladesh: Delta Subsidence, Seasonal Water Loading and Shortening Across the Burma Accretionary Prism and Shillong Massif

    NASA Astrophysics Data System (ADS)

    Steckler, M. S.; Mondal, D. R.; Nooner, S. L.; Akhter, S. H.; Seeber, L.; Bettadpur, S. V.; Sazedul Karim, C.; Howe, M.; Masson, F.; Maurin, T.; Rangin, C.

    2013-12-01

    We installed a suite of 25 GPS receivers between 2003 to 2012 covering the deltaic country of Bangladesh, which lies near the junction of the Indian Shield, the Himayalan collision belt and the Indo-Burman wedge. The crust of the Indian Shield thins southeastward in Bengal Basin across the hinge zone of an Early Cretaceous continental margin. The thin continental and/or oceanic crust of the Bengal Basin beyond the hinge zone is overlain by the southwest prograding Ganges-Brahmaputra Delta (GBD) creating a total sediment thickness of ≥16 km. The GBD is formed by the convergence of these great rivers which together supply >1GT/y of sediment. Their flow, the second largest on earth, is strongly seasonal and causes widespread flooding during the summer monsoon. The heavily-sedimented GBD is being overridden from the north by the Shillong Massif, a 2-km high basement-cored anticlinorium exposing Indian Shield, and from the east by the accretionary prism of the Indo-Burma wedge. The soft, oblique collision of the Burma platelet with the Bengal Basin and the GBD has built a large accretionary prism that widens northwards to 250-300 km. The prism extends westward up to half way across the GBD. The outer folds and thrust front are blind due to burial by the rapid sedimentation of the GBD. The GPS data in Bangladesh cover the frontal region of this unusual subaerial accretionary prism, while observations from India and Myanmar provide velocities for more internal parts of the system. The GPS velocities provide data on multiple processes taking place in the region. The vertical component shows both long-term and seasonal signals. The horizontal components quantify the shortening and lateral motion between the GBD and both the Indo-Burman wedge and Shillong Massif. The Indo-Burman convergence is oblique and partitioned into multiple strike-slip faults and a large number of thrust folds, presumably rooted into a basal megathrust.. The velocity gradients across the

  6. Highly Sideophile Element Abundance Constraints on the Nature of the Late Accretionary Histories of Earth, Moon and Mars

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Puchtel, I. S.; Brandon, A. D.; Horan, M. F.; James, O. B.

    2007-01-01

    The highly siderophile elements (HSE) include Re, Os, Ir, Ru, Pt and Pd. These elements are initially nearly-quantitatively stripped from planetary silicate mantles during core segregation. They then may be re-enriched in mantles via continued accretion sans continued core segregation. This suite of elements and its included long-lived radiogenic isotopes systems (Re-187 (right arrow) Os-187; Pt-190 (right arrow) Os-186) can potentially be used to fingerprint the characteristics of late accreted materials. The fingerprints may ultimately be useful to constrain the prior nebular history of the dominant late accreted materials, and to compare the proportion and genesis of late accretionary materials added to the inner planets. The past ten years have seen considerable accumulation of isotopic and compositional data for HSE present in the Earth's mantle, lunar mantle and impact melt breccias, and Martian meteorites. Here we review some of these data and consider the broader implications of the compiled data.

  7. Viscous sintering of volcanic ash

    NASA Astrophysics Data System (ADS)

    Wadsworth, F. B.; Scheu, B.; Vasseur, J.; Tuffen, H.; von Aulock, F. W.; Lavallée, Y.; Hess, K. U.; Dingwell, D. B.

    2014-12-01

    Volcanic ash is often deposited in a hot state. Volcanic ash containing glass, deposited above the glass transition interval, has the potential to sinter viscously both to itself (particle-particle) and to exposed surfaces. Here, we constrain the kinetics of this process experimentally under isothermal and non-isothermal conditions using standard glasses and volcanic ash. In the absence of external load, this process is dominantly driven by surface relaxation. In such cases the sintering process is rate-limited by the melt viscosity, the size of the particles and the melt-vapour interfacial tension. We propose a polydisperse continuum model that describes the transition from a packing of particles to a dense pore-free melt and evaluate its efficacy in describing the kinetics of volcanic viscous sintering. We apply our model to viscous sintering scenarios for cooling crystal-poor rhyolitic ash using the 2008 eruption of Chaitén volcano as a case example. We predict that moderate cooling rates result in the common observation of incomplete sintering and the preservation of pore networks. Finally we discuss the effect of crystallisation, external loading and volatile degassing or regassing during viscous sintering and assert that such complexities must be considered in the volcanic scenario.

  8. Magnetic fabrics of soft-sediment folded strata within a neogene accretionary complex, the Miura group, central Japan

    NASA Astrophysics Data System (ADS)

    Kanamatsu, Toshiya; Herrero-Bervera, Emilio; Taira, Asahiko

    2001-05-01

    Anisotropy of magnetic susceptibility (AMS) on the middle Miocene-Pleistocene sedimentary sequence in the Boso and Miura Peninsulas of central Japan was used to study 18 sites in the northern tectonic setting and 37 sites in the southern setting. This sequence is associated with abundant synsedimentary deformation structures of folding and faulting generated in accretionary tectonics. AMS results in different deformation settings such as the forearc, the accretionary prism and the trench were analyzed. The shapes of the dissimilar magnetic fabrics are compared using the shape parameter ( T) and the corrected anisotropy degree ( P') in the so-called T- P' diagrams. Our results have implied that the oblate fabric of the trench sediments can be regarded as the result of depositional and compactional processes alone. The AMS shape parameters obtained from the northern sequence (forearc) closely resemble an indication of undeformed trench sediments. In contrast, a different pattern is observed in the highly prolate-shaped AMS results of the southern sequence. The difference apparently reflects the degree of deformation in the three tectonic provinces. In order to understand the deformation mechanism of the sedimentary fabric, a detailed AMS study was made on one anticline system. An AMS evolution from an oblate fabric to a prolate fabric in the anticline system was observed. We also found that an AMS tectonic fabric occurred in the center of the anticline. Thickness correlations of the strata under study indicate that strained sediments formed in the central portion of the fold. As a consequence, one can say that this mechanism can modify the magnetic fabric from the sedimentary form to the tectonic form in a compressional regime.

  9. Paleozoic accretionary and collisional tectonics of the eastern Chinese Tianshan: implications for crustal growth of central Asia

    NASA Astrophysics Data System (ADS)

    Xiao, W. J.; Qin, K. Z.; Sun, S.; Li, J. L.

    2003-04-01

    The Paleozoic tectonics of Chinese Tianshan was complicated in the east by jointing of the NWW-trending Junggar and the E-W-trending East Tianshan belts. From South to North, this orogenic collage is subdivided into several tectonics terranes, which have recorded the Middle to Late Paleozoic geological history in framework of a complicated collision between two archipelago system lying along the northern Tarim and the southern Siberian margins, respectively. The southern archipelago system, constructed followed collapse of the northern passive margin of the Tarim, was mainly active in the Silurian to Early Carboniferous time, and was characterized by suturing of a Neoproterozoic to Late Devonian passive margin, the Tarim, in the south and a Silurian-Mid-Devonian arc terrane, the Kawabulak-Central Tianshan arc, in the north with squeezed intervening Late Devonian to Early Carboniferous backarc basins. The northern archipelago system was a Devonian-Carboniferous composite arc, which comprises the Carboniferous the Yamansu arc, the Early- to Mid-Carboniferous Kanguer accretionary forearc basin, the Devonian-Carboniferous Dananhu arc, the Xiaopu intra-arc basin, the Harlik arc, and the Kelameili composite arc system. These two archipelagos collided softly leaving a cryptic suture zone represented by the Late Carboniferous to Permian Mishigou-Weiya accretionary complex including ophiolitic fragments. Predominant northward subduction during final formation of the suture gave rise to a large-scale, post-collisional, south-directed thrust-and-fold belt in the Early Triassic. By deciphering the various tectonic terranes, this paper presents a new model for the evolution of this portion of Central Asia.

  10. Arc-parallel extension and fluid flow in an ancient accretionary wedge: The San Juan Islands, Washington

    USGS Publications Warehouse

    Schermer, E.R.; Gillaspy, J.R.; Lamb, R.

    2007-01-01

    Structural analysis of the Lopez Structural Complex, a major Late Cretaceous terrane-bounding fault zone in the San Juan thrust system, reveals a sequence of events that provides insight into accretionary wedge mechanics and regional tectonics. After formation of regional ductile flattening and shear-related fabrics, the area was crosscut by brittle structures including: (1) southwest-vergent thrusts, (2) extension veins and normal faults related to northwest-southeast extension, and (3) conjugate strike-slip structures that record northwest-southeast extension and northeast-southwest shortening. Aragonite-bearing veins are associated with thrust and normal faults, but only rarely with strike-slip faults. High-pressure, low-temperature (HP-LT) minerals constrain the conditions for brittle deformation to ???20 km and <250 ??C. The presence of similar structures elsewhere indicates that the brittle structural sequence is typical of the San Juan nappes. Sustained HP-LT conditions are possible only if structures formed in an accretionary prism during active subduction, which suggests that these brittle structures record internal wedge deformation at depth and early during uplift of the San Juan nappes. The structures are consistent with orogen-normal shortening and vertical thickening followed by vertical thinning and along-strike extension. The kinematic evolution may be related initially to changes in wedge strength, followed by response to overthickening of the wedge in an unbuttressed, obliquely convergent setting. The change in vein mineralogy indicates that exhumation occurred prior to the strike-slip event. The pressure and temperature conditions and spatial and temporal extent of small faults associated with fluid flow suggest a link between these structures and the silent earthquake process. ?? 2007 Geological Society of America.

  11. Predicting the Evolution of Faulting in Accretionary Prisms with Work Optimization: Insights from Numerical Simulations of Analog Experiments

    NASA Astrophysics Data System (ADS)

    McBeck, J.; Cooke, M. L.; Herbert, J. W.; Souloumiac, P.; Maillot, B.

    2015-12-01

    Accretionary wedges develop through the episodic, discrete propagation of imbricate thrust faults at the deformation front and advancement of the decollement surface. In this process, diffuse compaction, propagation of new fractures, and slip and opening along preexisting fractures accommodate cumulative deformation to differing degrees throughout the evolution of the wedge. Previous analyses suggest that the energy budget reveals how strain is partitioned within this episodic system near the onset of thrust faulting. In this contribution, we perform a work optimization analysis with 2D, boundary element method, Fric2D numerical models of accretionary wedges. We use the displacement field captured through particle image velocimetry analysis of scaled physical experiments in dry sand to inform the loading applied to the numerical models. We introduce planar faults of various dips and locations within the wedge, and calculate the gain in efficiency (ΔWext) produced by adding each fault to the wedge. We consider the faults that produce the largest ΔWext to be most energetically favorable, and thus likely to develop at the onset of discrete failure in the wedge. We compare the predictions of this parametric work optimization approach to the geometry of through-going faults observed in the physical analog experiment. We find that the numerical work analysis closely predicts the dip and location of the first forethrust observed in the experiment, as well as the dip of the first backthrust in the experiment. A similar parametric study with planar faults of differing lengths in the modeled wedge shows that the dip of the fault that optimizes work can vary with fault length, and that forethrusts consistently produce a greater gain in efficiency than backthrusts of equal lengths.

  12. Numerical Simulation on Ramp Initiation and Propagation in a Fold-and-thrust Belt and Accretionary Wedge

    NASA Astrophysics Data System (ADS)

    Hu, C.; Liu, X.; Shi, Y.

    2015-12-01

    Fold-and-thrust belts and accretionary wedge develop along compressive plate boundaries, both in hinterland and foreland. Under the long-term compressive tectonic loading, a series ramps will initiate and propagate along the wedge. How do the ramps initiate? What are the timing and spacing intervals between the ramps? How many patterns are there for the ramp propagation? These questions are basic for the study of ramp initiation and propagation. Many scholars used three different methods, critical coulomb wedge theory, analogue sandbox models, and numerical simulation to research the initiation and propagation of the ramps, respectively. In this paper, we set up a 2-D elastic-plastic finite element model, with a frictional contact plane, to simulate the initiation and propagation of the ramps. In this model, the material in upper wedge is homogenous, but considering the effects of gravity and long-term tectonic loading. The model is very simple but simulated results are very interesting. The simulated results indicate that the cohesion of upper wedge and dip angle of detachment plane have strong effects on the initiation and propagation of ramps. There are three different patterns of ramp initiation and propagation for different values of the cohesion. The results are different from those by previous analogue sandbox models, and numerical simulation, in which there is usually only one pattern for the ramp initiation and propagation. The results are consistent with geological survey for the ramp formation in an accretionary wedge. This study will provide more knowledge of mechanism of the ramp initiation and propagation in Tibetan Plateau and central Taiwan.

  13. Permeability of Silty Claystone and Turbidite Samples from IODP Expedition 348, Hole C0002P, Nankai Trough Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Song, C.; Underwood, M.

    2014-12-01

    One of the main objectives of IODP Expedition 348 was to characterize the variations of lithology and structure with depth in the interior of the Nankai Trough accretionary complex beneath the Kumano forearc basin (offshore SW Japan). Six cores were recovered from Hole C0002P between 2163 and 2218 mbsf. Four whole-round (WR) specimens from depths of 2174.98 to 2209.64 mbsf were tested for constant-flow permeability with a focus on thin interbeds of silty claystone and fine-grained turbidites. Samples are from lithostratigraphic Unit V (accreted trench or Shikoku Basin hemipelagic deposits). Coarser interbeds are important for assessing the prospects of flow through stratigraphic conduits. Our primary objective is to better understand how hydrogeologic properties of different lithologies respond to deformation within the accretionary prism. Equipment for permeability tests consists of a withdrawal-infuse syringe pump to simultaneously inject and extract pore fluid from the top and bottom of the specimen to generate hydraulic head difference. Specimens were trimmed for tests in both vertical direction (along-core) and horizontal direction (cross-core) with the diameter of 3.8 cm (1.5 in). The isotropic effective stress is set at 0.55 MPa. The WR specimens are heterogeneous. The major lithology is silty claystone to fine-grained silty claystone. Some intervals contain thin (~1.3 cm) oblique sandy layers and black organic bands. Bedding is steep to vertical (~70-80˚). One goal is to determine how this lithologic variability affects the anisotropy of permeability. Environmental SEM was used to image the cores (in multiple directions) to evaluate the relation between sediment microstructure and anisotropy of permeability.

  14. Field evidence for fault controlled intrusion of blue-schist-bearing melange into an accretionary wedge, Island Mountain, California

    SciTech Connect

    Lamons, R.

    1985-01-01

    Two lithologic units of the Franciscan are well exposed along a loop of the Eel River at Island Mountain. They are 1) zeolite or lower grade lithic graywackes, and 2) a 0.5 km wide band of black shaly melange containing blueschist, chert, greenstone, metagraywacke, and a graywacke-hosted copper deposit. Sedimentary features were not observed in the melange. The graywacke was subdivided on the basis of presence or absence of sodium-cobaltonitrate stained K-spar. Field relationships suggest that the blueschist-bearing melange was emplaced along steep NW-dipping faults in an accretionary wedge. Mapping of S. Jewett Rock and SW Lake Mountain quadrangles show narrow anastomosing bands of the melange following NW-trending faults. East of this band, graywackes without K-spar are folded along NW/SE axes. No folds were found to the west. Other Melange bands pinch out into faults which juxtapose graywackes of different facies. The sheared melange bands are not folded and shale beds in the graywacke show little shear so the melange bands are unlikely to be sheared olistostromes. The areal extent of graywacke is about ten times that of melange shales. Assuming this pattern continues laterally and at depth, the amount of ductile material in the melange is far less than that assumed by Cloos (1982) in his flow model for melange. The ductile melange may have been forced upward by metamorphically produced volatiles, or as a result of relative plate motion. It originated at depth, moved up along the top of a subducting slab, plucking clasts, then splayed upward into pre-existing faults in the accretionary wedge.

  15. Flexural bending-induced plumelets and their seamounts in accretionary (Japanese-style) and collisional (Tethyan-style) orogenic belts

    NASA Astrophysics Data System (ADS)

    Hirano, N.; Dilek, Y.

    2015-12-01

    Seamounts and seamount chains are common in both the upper and lower plates of active subduction zones. Their OIB-type volcanic products are distinctly different from suprasubduction zone (arc, forearc and backarc) generated volcanic rocks in terms of their compositions and mantle sources. Tectonic accretion of such seamounts into the Japanese archipelago in the NW Pacific and into subduction-accretion complexes and active margins of continents/microcontinents within the Tethyan realm during the Cretaceous played a significant role in continental growth. Seamount assemblages comprise alkaline volcanic rocks intercalated with radiolarian and hemipelagic chert, and limestone, and may also include hypabyssal dolerite and gabbro intrusions. In the Tethyan orogenic belts these seamount rocks commonly occur as km-scale blocks in mélange units beneath the late Jurassic - Cretaceous ophiolites nappes, whereas on the Japanese islands they form discrete, narrow tectonic belts within the late Jurassic - Cretaceous accretionary prism complexes. We interpret some of these OIB occurrences in the Japanese and Tethyan mountain belts as asperities in downgoing oceanic plates that formed in <10 million years before their accretion. Their magmas were generated by decompressional melting of upwelling asthenosphere, without any significant mantle plume component, and were brought to the seafloor along deep-seated brittle fractures that developed in the flexed, downgoing lithosphere as it started bending near a trench. The modern occurrences of these "petit-spot volcanoes" are well established in the northwestern Pacific plate, off the coast of Japan. The proposed mechanism of the formation of these small seamounts better explains the lack of hotspot trails associated with their occurrence in the geological record. Magmatic outputs of such flexural bending-induced plumelets should be ubiquitious in the accretionary (Japanese-style) and collisional (Tethyan-style) orogenic belts.

  16. Early Paleozoic accretionary orogenesis along northern margin of Gondwana constrained by high-Mg metaigneous rocks, SW Yunnan

    NASA Astrophysics Data System (ADS)

    Xing, Xiaowan; Wang, Yuejun; Cawood, Peter A.; Zhang, Yuzhi

    2015-12-01

    SW Yunnan of China constituted part of the northern margin of Gondwana facing the proto-Tethys ocean in the early Paleozoic. However, the evolution of the region and its relationship with the accretionary orogenism have been poorly established. This paper reports a set of new zircon U-Pb age data and whole-rock major oxides, elemental and Sr-Nd isotopic data for early Paleozoic metavolcanic rocks from the previously defined Lancang Group and reveals the development of an Ordovician suprasubduction zone in SW Yunnan. Zircon U-Pb ages of 462 ± 6 and 454 ± 27 Ma for two representative samples indicate eruption of the volcanic rocks in the Late Ordovician. Geochemical data for the metavolcanic rocks together with other available data indicate a calc-alkaline affinity with high Al2O3 (13.04-18.77 wt%) and low TiO2 (0.64-1.00 wt%). They have Mg-numbers ranging from 62 to 50 with SiO2 of 53.57-69.10 wt%, compositionally corresponding to the high-Mg andesitic rocks. They display enrichments in LREEs and LILEs with significant Eu negative anomalies (δEu = 0.20-0.33), and depletions in HFSEs, similar to arc volcanic rocks. Their initial 87Sr/86Sr ratios range from 0.721356 to 0.722521 and ɛNd(t) values from -7.63 to -7.62 with Nd model ages of 2.06-2.10 Ga. Integration of ages and geochemical data with available geological observations, we propose the presence of Ordovician magmatism related to proto-Tethyan evolution in SW Yunnan and the metaigneous rocks formed in an island-arc setting. They were part of a regional accretionary orogen that extended along the northern margin of Gondwana during Neoproterozoic to early Paleozoic period.

  17. A comparison between sludge ash and fly ash on the improvement in soft soil.

    PubMed

    Lin, Deng-Fong; Lin, Kae-Long; Luo, Huan-Lin

    2007-01-01

    In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4-2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20-30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil. PMID:17269231

  18. A comparison between sludge ash and fly ash on the improvement in soft soil.

    PubMed

    Lin, Deng-Fong; Lin, Kae-Long; Luo, Huan-Lin

    2007-01-01

    In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4-2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20-30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil.

  19. A comparison between sludge ash and fly ash on the improvement in soft soil

    SciTech Connect

    Deng-Fong Lin; Kae-Long Lin; Huan-Lin Luo

    2007-01-15

    In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4 2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20 30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil. 9 refs., 5 figs., 2 tabs.

  20. Identifying glass compositions in fly ash

    NASA Astrophysics Data System (ADS)

    Aughenbaugh, Katherine; Stutzman, Paul; Juenger, Maria

    2016-01-01

    In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS), calcium aluminosilicate glasses (CAS), a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  1. Gasification of ash-containing solid fuels

    SciTech Connect

    Moss, G.

    1983-03-01

    Ash-contaminated solid or semi-solid fuel is passed into the bottom zone of a fluidized bed gasifier, preferably containing cao to fix labile sulfur moieties, and gasified at a temperature below the ash-softening point. The resulting char and ash of relatively low size and/or weight pass to a top zone of the bed wherein the char is gasified at a temperature above the ash-softening point whereby a substantial proportion of the ash sticks to and agglomerates with solids in the top zone until the particle size and/or weight of the resulting agglomerates causes them to sink to the bottom of the gasifier from where they can be recovered. The hot gases leaving the top of the gasifying bed have a reduced burden of entrained ash, and may be cooled to prevent any entrained ash adhering to downstream equipment through which the gases pass.

  2. ACAA fly ash basics: quick reference card

    SciTech Connect

    2006-07-01

    Fly ash is a fine powdery material created when coal is burned to generate electricity. Before escaping into the environment via the utility stacks, the ash is collected and may be stored for beneficial uses or disposed of, if necessary. The use of fly ash provides environmental benefits, such as the conservation of natural resources, the reduction of greenhouse gas emissions and eliminating the needed for ash disposal in landfills. It is also a valuable mineral resource that is used in construction and manufacturing. Fly ash is used in the production of Portland cement, concrete, mortars and stuccos, manufactured aggregates along with various agricultural applications. As mineral filler, fly ash can be used for paints, shingles, carpet backing, plastics, metal castings and other purposes. This quick reference card is intended to provide the reader basic source, identification and composition, information specifically related to fly ash.

  3. Interspecific variation in resistance to emerald ash borer (Coleoptera: Buprestidae) among North American and Asian ash (Fraxinus spp.).

    PubMed

    Rebek, Eric J; Herms, Daniel A; Smitley, David R

    2008-02-01

    We conducted a 3-yr study to compare the susceptibility of selected North American ash and an Asian ash species to emerald ash borer, Agrilus planipennis Fairmaire, an invasive wood-boring beetle introduced to North America from Asia. Because of a coevolutionary relationship between Asian ashes and emerald ash borer, we hypothesized an Asian ash species, Manchurian ash, is more resistant to the beetle than its North American congeners. Consistent with our hypothesis, Manchurian ash experienced far less mortality and yielded far fewer adult beetles than several cultivars of North American green and white ash. Surprisingly, a black ash (North American) x Manchurian ash hybrid was highly susceptible to emerald ash borer, indicating this cultivar did not inherit emerald ash borer resistance from its Asian parent. A corollary study investigated the efficacy of soil-applied imidacloprid, a systemic, neonicotinoid insecticide, for controlling emerald ash borer in each of the five cultivars. Imidacloprid had no effect on emerald ash borer colonization of Manchurian ash, which was low in untreated and treated trees. In contrast, imidacloprid did enhance survival of the North American and hybrid cultivars and significantly reduced the number of emerald ash borer adults emerging from green and white ash cultivars. We identify a possible mechanism of resistance of Manchurian ash to emerald ash borer, which may prove useful for screening, selecting, and breeding emerald ash borer-resistant ash trees.

  4. Ultrasonic ash/pyrite liberation

    SciTech Connect

    Yungman, B.A.; Buban, K.S.; Stotts, W.F.

    1990-06-01

    The objective of this project was to develop a coal preparation concept which employed ultrasonics to precondition coal prior to conventional or advanced physical beneficiation processes such that ash and pyrite separation were enhanced with improved combustible recovery. Research activities involved a series of experiments that subjected three different test coals, Illinois No. 6, Pittsburgh No. 8, and Upper Freeport, ground to three different size fractions (28 mesh [times] 0, 200 mesh [times] 0, and 325 mesh [times] 0), to a fixed (20 kHz) frequency ultrasonic signal prior to processing by conventional and microbubble flotation. The samples were also processed by conventional and microbubble flotation without ultrasonic pretreatment to establish baseline conditions. Product ash, sulfur and combustible recovery data were determined for both beneficiation processes.

  5. Active mineral additives of sapropel ashes

    NASA Astrophysics Data System (ADS)

    Khomich, V. A.; Danilina, E. V.; Krivonos, O. I.; Plaksin, G. V.

    2015-01-01

    The goal of the presented research is to establish a scientific rational for the possibility of sapropel ashes usage as an active mineral additive. The research included the study of producing active mineral additives from sapropels by their thermal treatment at 850900 °C and afterpowdering, the investigation of the properties of paste matrix with an ash additive, and the study of the ash influence on the cement bonding agent. Thermogravimetric analysis and X-ray investigations allowed us to establish that while burning, organic substances are removed, clay minerals are dehydrated and their structure is broken. Sapropel ashes chemical composition was determined. An amorphous ash constituent is mainly formed from silica of the mineral sapropel part and alumosilicagels resulted from clay minerals decomposition. Properties of PC 400 and PC 500A0 sparopel ash additives were studied. Adding ashes containing Glenium plasticizer to the cement increases paste matrix strength and considerably reduces its water absorption. X-ray phase analysis data shows changes in the phase composition of the paste matrix with an ash additive. Ash additives produce a pozzolanic effect on the cement bonding agent. Besides, an ash additive due to the alumosilicagels content causes transformation from unstable calcium aluminate forms to the stable ones.

  6. Rapid toxicity screening of gasification ashes.

    PubMed

    Zhen, Xu; Rong, Le; Ng, Wei Cheng; Ong, Cynthia; Baeg, Gyeong Hun; Zhang, Wenlin; Lee, Si Ni; Li, Sam Fong Yau; Dai, Yanjun; Tong, Yen Wah; Neoh, Koon Gee; Wang, Chi-Hwa

    2016-04-01

    The solid residues including bottom ashes and fly ashes produced by waste gasification technology could be reused as secondary raw materials. However, the applications and utilizations of these ashes are very often restricted by their toxicity. Therefore, toxicity screening of ash is the primary condition for reusing the ash. In this manuscript, we establish a standard for rapid screening of gasification ashes on the basis of in vitro and in vivo testing, and henceforth guide the proper disposal of the ashes. We used three different test models comprising human cell lines (liver and lung cells), Drosophila melanogaster and Daphnia magna to examine the toxicity of six different types of ashes. For each ash, different leachate concentrations were used to examine the toxicity, with C0 being the original extracted leachate concentration, while C/C0 being subsequent diluted concentrations. The IC50 for each leachate was also quantified for use as an index to classify toxicity levels. The results demonstrated that the toxicity evaluation of different types of ashes using different models is consistent with each other. As the different models show consistent qualitative results, we chose one or two of the models (liver cells or lung cells models) as the standard for rapid toxicity screening of gasification ashes. We may classify the gasification ashes into three categories according to the IC50, 24h value on liver cells or lung cells models, namely "toxic level I" (IC50, 24h>C/C0=0.5), "toxic level II" (C/C0=0.05ashes generated in gasification plants every day. Subsequently, appropriate disposal methods can be recommended for each toxicity category.

  7. Volcanic Ash on Slopes of Karymsky

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A volcanic eruption can produce gases, lava, bombs of rock, volcanic ash, or any combination of these elements. Of the volcanic products that linger on the land, most of us think of hardened lava flows, but volcanic ash can also persist on the landscape. One example of that persistence appeared on Siberia's Kamchatka Peninsula in spring 2007. On March 25, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the area around the Karymsky Volcano. In this image, volcanic ash from earlier eruptions has settled onto the snowy landscape, leaving dark gray swaths. The ash stains are confined to the south of the volcano's summit, one large stain fanning out toward the southwest, and another toward the east. At first glance, the ash stain toward the east appears to form a semicircle north of the volcano and sweep back east. Only part of this dark shape, however, is actually volcanic ash. Near the coast, the darker color may result from thicker vegetation. Similar darker coloring appears to the south. Volcanic ash is not really ash at all, but tiny, jagged bits of rock and glass. These jagged particles pose serious health risks to humans and animals who might inhale them. Likewise, the ash poses hazards to animals eating plants that have been coated with ash. Because wind can carry volcanic ash thousands of kilometers, it poses a more far-reaching hazard than other volcanic ejecta. Substantial amounts of ash can even affect climate by blocking sunlight. Karymsky is a stratovolcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. It is one of many active volcanoes on Russia's Kamchatka Peninsula, which is part of the 'Ring of Fire' around the Pacific Rim. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  8. Vitrification of municipal solid waste incineration fly ash using biomass ash as additives.

    PubMed

    Alhadj-Mallah, Moussa-Mallaye; Huang, Qunxing; Cai, Xu; Chi, Yong; Yan, JianHua

    2015-01-01

    Thermal melting is an energy-costing solution for stabilizing toxic fly ash discharged from the air pollution control system in the municipal solid waste incineration (MSWI) plant. In this paper, two different types of biomass ashes are used as additives to co-melt with the MSWI fly ash for reducing the melting temperature and energy cost. The effects of biomass ashes on the MSWI fly ash melting characteristics are investigated. A new mathematical model has been proposed to estimate the melting heat reduction based on the mass ratios of major ash components and measured melting temperature. Experimental and calculation results show that the melting temperatures for samples mixed with biomass ash are lower than those of the original MSWI fly ash and when the mass ratio of wood ash reaches 50%, the deformation temperature (DT), the softening, hemisphere temperature (HT) and fluid temperature (FT) are, respectively, reduced by 189°C, 207°C, 229°C, and 247°C. The melting heat of mixed ash samples ranges between 1650 and 2650 kJ/kg. When 50% wood ash is mixed, the melting heat is reduced by more than 700 kJ/kg for the samples studied in this paper. Therefore, for the vitrification treatment of the fly ash from MSW or other waste incineration plants, wood ash is a potential fluxing assistant. PMID:25220259

  9. Vitrification of municipal solid waste incineration fly ash using biomass ash as additives.

    PubMed

    Alhadj-Mallah, Moussa-Mallaye; Huang, Qunxing; Cai, Xu; Chi, Yong; Yan, JianHua

    2015-01-01

    Thermal melting is an energy-costing solution for stabilizing toxic fly ash discharged from the air pollution control system in the municipal solid waste incineration (MSWI) plant. In this paper, two different types of biomass ashes are used as additives to co-melt with the MSWI fly ash for reducing the melting temperature and energy cost. The effects of biomass ashes on the MSWI fly ash melting characteristics are investigated. A new mathematical model has been proposed to estimate the melting heat reduction based on the mass ratios of major ash components and measured melting temperature. Experimental and calculation results show that the melting temperatures for samples mixed with biomass ash are lower than those of the original MSWI fly ash and when the mass ratio of wood ash reaches 50%, the deformation temperature (DT), the softening, hemisphere temperature (HT) and fluid temperature (FT) are, respectively, reduced by 189°C, 207°C, 229°C, and 247°C. The melting heat of mixed ash samples ranges between 1650 and 2650 kJ/kg. When 50% wood ash is mixed, the melting heat is reduced by more than 700 kJ/kg for the samples studied in this paper. Therefore, for the vitrification treatment of the fly ash from MSW or other waste incineration plants, wood ash is a potential fluxing assistant.

  10. The Variscan accretionary prism in the Kaczawa Mountains (W Sudetes, SW Poland): lithostratigraphic, sedimentological, volcanic, metamorphic and structural evidence

    NASA Astrophysics Data System (ADS)

    Kryza, Ryszard; Kostylew, Joanna; Zalasiewicz, Jan

    2013-04-01

    The Sudetes (SW Poland) at the NE edge of the Bohemian Massif (Central-European Variscides) are a structural mosaic comprising various basement units, some interpreted as fragments of a Variscan accretionary prism (Baranowski et al., 1990; Collins et al., 2000; Kryza & Zalasiewicz, 2008). The best example is the Kaczawa structural unit in the West Sudetes. Its accretionary nature is evident from: Lithostratigraphy, sedimentology and volcanism. Neighbouring tectonic units of the Kaczawa Mountains contain different fragments of Palaeozoic successions: (a) a Cambrian (and Neoproterozoic?) - Ordovician volcano-sedimentary sequence (with WP type bimodal volcanic and shallow-water sedimentary rocks), (b) Silurian - Devonian MORB-type metabasalts, shales and cherts (with graptolites and conodonts), and (c) Late Devonian - Early Carboniferous polygenetic mélange bodies that record overlapping dynamic sedimentary and tectonic processes. This suggests evolving palaeotectonic environments, from initial rift within continental crust, through mature basin likely underlined by oceanic-type lithosphere, to a subduction setting (mélanges; Baranowski et al., 1990; Collins et al., 2000; Kryza & Zalasiewicz, 2008, and refs. therein). Metamorphism. Diverse PT metamorphic paths detected in various tectonic units of the Kaczawa Mountains are strong evidence for the subduction/accretionary affinity. Relatively higher-grade metamorphic units bear evidence of blueschist-facies metamorphism, overprinted by a low-T greenschist facies event (pseudosection modelling yielded: ~270oC and 8.5 kb for the peak-P, and ~310oC and 6 kb for the peak-T stages). The estimated P/T gradient of ~10 oC/km is typical of a subduction setting (Kryza et al., 2011). Other tectonic units, including the mélange bodies, experienced lower-grade metamorphic parageneses (e.g. widespread pumpellyite) and white-mica structural data (Kostylew et al., 2013; and refs. therein). The diverse metamorphic PT paths indicate

  11. A potential record of slow slip earthquakes from the Kodiak Accretionary Complex and the role of silica redistribution

    NASA Astrophysics Data System (ADS)

    Fisher, D. M.

    2013-12-01

    Slow slip earthquakes are observed along both accretionary and nonaccretionary subduction zones with continuous GPS networks, so one would expect that deeply exhumed paleo-decollements in ancient accretionary complexes would carry a record of these events in the form of fault fabrics, microstructures, or veins. One potential example is within the Central Belt of the Late Cretaceous Kodiak Formation, a 10's of meters thick, subhorizontal paleo-decollement zone from the Kodiak accretionary complex in southwest Alaska that is exposed for over 100 km along strike in a regional culmination in the Kodiak archipelago. Here, the main criteria that are likely necessary for slow slip earthquakes are satisfied: 1) proximity to the downdip transition from velocity weakening to velocity strengthening, 2) low effective stresses driven by high fluid pressures related to the onset of dehydration reactions in low permeability rocks, 3) dilation, with hundreds of events of cracking and crack closure, and 4) a regime of simple shear. The central belt is pervasively veined at the scale of mm's, but there are larger veins organized into en echelon sets that lie in seaward dipping arrays regularly spaced at ~0.5 m with small vugs in many cases. There are two types of microstructures in these veins that represent different crack closure mechanisms: crack seal bands and collapse residues. All the early, closely spaced veins close only by sealing (continuous crack seal bands of metamorphic chlorite grown from the seeds on the crack wall), but the center of the larger veins in en echelon sets show a temporal transition from continuous crack seal bands, to discontinuous crack seal bands, to inclusion free growth of euhedral crystals, with bands of collapse residues of dissolved wall rock. Crack seal bands indicate ~10 microns as the median crack aperture, with a large tail in the distribution toward larger values. Fluid inclusion trails that track the crack displacement path systematically

  12. Large Erosional Features on the Cascadia Accretionary Wedge Imaged with New High-Resolution Multibeam Bathymetry and Seismic Datasets

    NASA Astrophysics Data System (ADS)

    Beeson, J. W.; Goldfinger, C.

    2013-12-01

    Utilizing new high resolution multibeam bathymetric data along with chirp sub-bottom and multichannel seismic reflection (MCS) data, we identified remarkable erosional features on the toe of the Cascadia accretionary wedge near Willapa Canyon, offshore Washington, USA. Bathymetric data was compiled from the Cascadia Open-Access Seismic Transects (COAST) cruise and from the site survey cruise for the Cascadia Initiative. These features loosely resemble slope failures of the frontal thrust, but can be distinguished from such failures by several key features: They incise the crest of the frontal thrust and encompass the landward limb; They have floors below the level of the abyssal plain, similar to plunge pool morphology; They show no evidence of landslide blocks at the base of the slope indicative of block sliding. The features where likely formed during the latest Pleistocene based on post event deposition, cross-cutting relationships with Juan de Fuca Channel and the Willapa Channel levees and wave field, and post event slip on the frontal thrust of the Cascadia accretionary prism. The Holocene levees of both Willapa Channel and Juan de Fuca Channel overlap these older features, and clearly place an upper bound on the age of the erosional features in the latest Pleistocene. A lower bound is estimated from a sub-bottom profile that images ~30 meters of post scour sediment fill. Using existing literature of Holocene and Pleistocene sedimentation rates we estimate a lower age bound between ~23,000 - 56,000 y.b.p. We also map a fault scarp within the erosional feature, with ~60 m of vertical offset. Using multi-channel seismic reflection profiles from the COAST cruise we interpret this scarp as the surface expression of the landward vergent frontal thrust fault. The apparent short duration of the erosional event along the seaward margin of the accretionary wedge, coupled with the presence of the fresh fault scarp within the erosion zone, are indicative of a dormant

  13. Can vegetative ash be water repellent?

    NASA Astrophysics Data System (ADS)

    Bodí, M. B.; Cerdà, A.; Mataix-Solera, J.; Doerr, S. H.

    2012-04-01

    In most of the literature, ash is referred to as a highly wettable material (e.g. Cerdà and Doerr, 2008; Etiegni and Campbell, 1991; Woods and Balfour 2010). However, the contrary was suggested in few articles, albeit with no further quantification (Gabet and Sternberg, 2008; Khanna et al., 1996; Stark, 1977). To clarify this question, water repellency measurements on ash using the Water Drop Penetration Times (WDPT) method were performed on ash from Mediterranean ecosystems and it was found to be water repellent (Bodí et al. 2011). Water repellency on ash from different wildfires ranged from 40 to 10 % occurrence with samples being extreme repellent (lasting more than 3600 s to penetrate). Part of the ash produced in the laboratory was also water repellent. After that, other ash samples had been found water repellent in wildfires in Colorado (unpublished results), Portugal (Gonzalez-Pelayo, 2009), or in prescribed fires in Australia (Bodí et al. 2011b; Petter Nyman, personnal communication). All the samples exhibiting water repellent properties had in common that were combusted at low temperatures, yielding in general ash with dark colour and contents of organic carbon of more than 18 % (Bodí et al. 2011a), although these properties were not exactly proportional to its water repellency occurrence or persistence. In addition, the species studied in Bodí et al. (2011) had been found to produce different levels of WR repellency, being ash from Pinus halepensis more repellent than that from Quercus coccifera and Rosmarins officinalis. Ash from Eucaliptus radiata had been found also very water repellent, as Pinus halepensis (unpublished data). The reasons of the existance of water repellent ash are that the charred residue produced by fire (an also contained in the ash) can contain aromatic compounds that have a lower free energy than water and therefore behave as hydrophobic materials with reduced solubility (Almendros et al., 1992 and Knicker, 2007

  14. Effect of addition of pond ash and fly ash on properties of ash-clay burnt bricks.

    PubMed

    Sarkar, Ritwik; Singh, Nar; Das, Swapan Kumar

    2007-12-01

    Two industrial solid waste products generated by Indian coal-fired power plants, namely pond ash and fly ash, were used in combination with local clay to develop building bricks. The clay were mixed with the two different ashes in the range 10 to 90 wt.%, hydraulically pressed and fired at 1000 degrees C. The fired products were characterized for various quality properties required for building bricks. The properties of the optimal compositions were compared with conventional red clay bricks including the developed microstructures and the comparative study generally showed that te ash-clay bricks were of superior quality to the conventional products.

  15. Volcanic ash impacts on critical infrastructure

    NASA Astrophysics Data System (ADS)

    Wilson, Thomas M.; Stewart, Carol; Sword-Daniels, Victoria; Leonard, Graham S.; Johnston, David M.; Cole, Jim W.; Wardman, Johnny; Wilson, Grant; Barnard, Scott T.

    2012-01-01

    Volcanic eruptions can produce a wide range of hazards. Although phenomena such as pyroclastic flows and surges, sector collapses, lahars and ballistic blocks are the most destructive and dangerous, volcanic ash is by far the most widely distributed eruption product. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to significant societal impacts. Even relatively small eruptions can cause widespread disruption, damage and economic loss. Volcanic eruptions are, in general, infrequent and somewhat exotic occurrences, and consequently in many parts of the world, the management of critical infrastructure during volcanic crises can be improved with greater knowledge of the likely impacts. This article presents an overview of volcanic ash impacts on critical infrastructure, other than aviation and fuel supply, illustrated by findings from impact assessment reconnaissance trips carried out to a wide range of locations worldwide by our international research group and local collaborators. ‘Critical infrastructure’ includes those assets, frequently taken for granted, which are essential for the functioning of a society and economy. Electricity networks are very vulnerable to disruption from volcanic ash falls. This is particularly the case when fine ash is erupted because it has a greater tendency to adhere to line and substation insulators, where it can cause flashover (unintended electrical discharge) which can in turn cause widespread and disruptive outages. Weather conditions are a major determinant of flashover risk. Dry ash is not conductive, and heavy rain will wash ash from insulators, but light rain/mist will mobilise readily-soluble salts on the surface of the ash grains and lower the ash layer’s resistivity. Wet ash is also heavier than dry ash, increasing the risk of line breakage or tower/pole collapse. Particular issues for water

  16. Volcanic ash impacts on critical infrastructure

    NASA Astrophysics Data System (ADS)

    Wilson, Thomas M.; Stewart, Carol; Sword-Daniels, Victoria; Leonard, Graham S.; Johnston, David M.; Cole, Jim W.; Wardman, Johnny; Wilson, Grant; Barnard, Scott T.

    2012-01-01

    Volcanic eruptions can produce a wide range of hazards. Although phenomena such as pyroclastic flows and surges, sector collapses, lahars and ballistic blocks are the most destructive and dangerous, volcanic ash is by far the most widely distributed eruption product. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to significant societal impacts. Even relatively small eruptions can cause widespread disruption, damage and economic loss. Volcanic eruptions are, in general, infrequent and somewhat exotic occurrences, and consequently in many parts of the world, the management of critical infrastructure during volcanic crises can be improved with greater knowledge of the likely impacts. This article presents an overview of volcanic ash impacts on critical infrastructure, other than aviation and fuel supply, illustrated by findings from impact assessment reconnaissance trips carried out to a wide range of locations worldwide by our international research group and local collaborators. ‘Critical infrastructure’ includes those assets, frequently taken for granted, which are essential for the functioning of a society and economy. Electricity networks are very vulnerable to disruption from volcanic ash falls. This is particularly the case when fine ash is erupted because it has a greater tendency to adhere to line and substation insulators, where it can cause flashover (unintended electrical discharge) which can in turn cause widespread and disruptive outages. Weather conditions are a major determinant of flashover risk. Dry ash is not conductive, and heavy rain will wash ash from insulators, but light rain/mist will mobilise readily-soluble salts on the surface of the ash grains and lower the ash layer’s resistivity. Wet ash is also heavier than dry ash, increasing the risk of line breakage or tower/pole collapse. Particular issues for water

  17. Pressure Wave Propagation along the Décollement of the Nankai Accretionary Wedge: Implications for Aseismic Slip Events

    NASA Astrophysics Data System (ADS)

    Joshi, A.; Appold, M. S.

    2015-12-01

    Seismic and hydrologic observations of the Nankai subduction zone made by the Ocean Drilling Program suggest that pore fluid pressures within the accretionary wedge décollement are highly overpressured to near lithostatic values below depths of 2 km beneath the sea floor as a result of sediment diagenesis and dehydration of the subducting oceanic plate. This overpressured zone is also observed to discharge pulses of high fluid pressure that migrate up-dip along the décollement at rates of 1's of km/day. These high pressure pulses along the décollement may cause large enough reductions in the local effective stress to account for aseismic slip events that have been found to propagate also at rates of 1's of km/day. Because elevated fluid pressure and correspondingly decreased effective stress can lead to a dilation of porosity, the pressure waves may become effective agents of fluid transport that can travel more quickly than fluids flowing in the background Darcian flow regime. The purpose of the present study was to seek theoretical confirmation that pressure waves are able to travel quickly enough to account for the seismic and hydrological observations documented. This confirmation was sought through a transient one-dimensional numerical solution to the differential fluid mass conservation equation for an elastic porous medium. Results of the numerical simulations show that when overpressures at depths greater than 2 km in the décollement exceed lithostatic pressure by at least 3%, pressure waves are formed that migrate up-dip at rates fast enough to account for aseismic slip over a broad range of geologic conditions. Pressure waves spawned from these depths in the décollement may travel fast enough to account for aseismic slip when overpressures there are as low as 99% of lithostatic pressure, but require low specific storage of 3×10-6 m-1, high sensitivity of permeability to effective stress, low permeability no higher than about 10-21 m2 at depths below

  18. Timing of magmatism and migmatization in the 2.0-1.8 Ga accretionary Svecokarelian orogen, south-central Sweden

    NASA Astrophysics Data System (ADS)

    Johansson, Åke; Stephens, Michael B.

    2016-07-01

    Hedesunda-Tierp sample area. The close spatial and temporal interplay between ductile deformation, magmatism and migmatization, the P-T metamorphic conditions, and the continuation of similar magmatic activity around and after 1.8 Ga support solely accretionary rather than combined accretionary and collisional orogenic processes as an explanation for the metamorphism. The generally lower metamorphic grade and restricted influence of the younger metamorphic episode, at least at the ground surface level, distinguishes the central part of the Bergslagen lithotectonic unit from the migmatite belts further north and south.

  19. Splay Faults and Associated Mass Transport Deposits in the Manila Accretionary Wedge near Taiwan: Implications for Geohazards

    NASA Astrophysics Data System (ADS)

    Lin, A. T.; Liu, C. S.; Dirgantara, F.

    2015-12-01

    Plate interface megathrusts are major seismogenic faults in subduction zone, capable of generating great earthquakes with widespread submarine landslides and damaging tsunami. Upward branching of megathrusts results in splay faults in the accretionary wedge. Reflection seismic data across the accretionary wedge off southern Taiwan, reveal at least two strands of splay faults as well as multiple stacked mass transport deposits (MTDs) nearby the faults. With the help of sediment coring and age datings in the vicinity of the splay fault, implications for temporal evolution of the mass wasting processes and episodic activities of splay faults are discussed in this paper. Seismic data show two branches of arcward and gently-dipping splay faults with two slope basins lying in the footwall and hangingwall of the faults, respectively. The older and buried splay fault is inactive as the fault tip is covered by up to 1000 m thick sediments in the footwall slope basin, indicating that it ceased to be active around 0.5 Ma ago. Repeated slip of this fault prior to ~0.5 Ma ago may also result in 4 stacked and multiple mass transport deposits (MTDs) of up to 700-m thick found in vicinity of this fault. This fossil splay fault is characterized by reflection polarity similar to that of seafloor, indicative of low water saturation along the fault zone and hence not an active fluid conduit. The younger and overlying splay fault cuts through the seafloor and the emergent fault tip lying at the toe of steep slope (~ 15 degree) with significant slope break. There is also a 500-m horizontal offset, between the buried paleo-seafloor in the footwall and the present-day seafloor on the hangingwall. The reflection polarity of this fault zone is reversed to that of seafloor, indicating fluid rich for this fault patch. These lines of evidence suggest that this young splay fault is an active fault with active fluid circulation along the fault. Our results indicate that the old splay fault

  20. Fluid circulations in the depths of accretionary prism: the record of quartz from the Shimanto Belt, Japan

    NASA Astrophysics Data System (ADS)

    Raimbourg, Hugues; Vacelet, Maxime; Ramboz, Claire; Famin, Vincent; Augier, Romain; Palazzin, Giulia

    2014-05-01

    Fluids present in the depths of subduction zones play a major role on seismogenesis, although fluid circulations paths and physico-chemical conditions are still largely unknown. Two main reservoirs of water, either in the pores of sediments or bound to hydrous minerals, release large amounts of water in the relatively shallow and deep domains of subduction zones, respectively. The usual model of circulation assumes then a bottom-up circulation driven by fluid pressure gradients. This study aims at reassessing this model, using the record of rocks from a paleo-accretionary prism, the Shimanto Belt in Japan. These rocks, buried to 5kbars and 300° C (Toriumi and Teruya, Modern Geology, 1988), were affected by pervasive fracturing throughout their history, from burial to exhumation. The quartz filling these fractures and the fluid inclusions that it contains keep the track of the fluid associated with the rock evolution. Using a combined approach of microstructural observations by optical microscopy and cathodoluminescence (CL), and chemical characterization by electron and ion microprobe as well as microthermometry, we show that there are actually two distinct fluids that have cyclically wetted the rock at depth. The first one is an 'external' fluid penetrating through macroscopic fractures and precipitating a quartz blue in CL. In contrast, a 'local' fluid attended the formation of quartz brown in CL, precipitating in microfractures or associated with ductile recrystallization. The two fluids are also chemically distinct: Both have a salinity close to seawater, but the local fluid is fresher than the external one. In addition, the external fluid is richer in aluminum than the local one. Finally, the external fluid is very slightly depleted in δ18O, although the difference is probably not significant and the first-order isotopic signal is a buffering by host rock. Our interpretation of microstructures and chemical signatures is that the external fluid is seawater

  1. Initiation and development of slickenlined surfaces in clay-rich material of the Nankai Trough accretionary prism

    NASA Astrophysics Data System (ADS)

    Crespo-Blanc, Ana; Schleicher, Anja

    2016-04-01

    During the International Ocean Discovery Program (IODP) Expedition 348, which is part of the Nankai Trough Seismogenic Zone Experiment (stage 3), the drilling vessel Chikyu advanced the deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula (Japan), from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf. Underlying the Kumano Basin sediments, the Nankai accretionary prism appears, below 975.5 mbsf. It accreted during Upper Miocene to Pliocene times and is formed mainly by turbiditic silty claystone with rarely observed sandstone intercalations. Cuttings from both the 1-4 mm and >4 mm size fractions were investigated, showing slickenlined surfaces and deformation bands together with carbonate veins throughout the entire section from 1045.5 until 3058.5 mbsf. A scaly fabric is increasingly observed below approximately 2400 mbsf. Clay-rich cuttings were selected at different depth for specific SEM-EDS analysis, in order to investigate the initiation and development of the slickenlined surfaces, from both a structural and mineralogical point of view. Two end-members of the slickenlined surface types were observed: a) isolated smooth and uniform planes, between 20 and 50 μm long, formed by single grains of smectite with marked lineations and frequently jagged boundaries and b) microfaults (longer than 100 μm) with sharp boundaries to the undeformed rock, formed by aggregates of illite and smectite and with a well-developed lineation. In transition between these two end-member types, planes that are apparently unconnected draw a single plane and show subparallel lineations. Concerning the orientation of the slickenlines, it seems to be coherent with that observed in an array of conjugated faults, i.e. all the slickenlines belong to the same plane, in turn sub-perpendicular to the intersection of conjugated planes. These observations suggest that the slickenlined surfaces initiated along single grains of smectite and that with increasing

  2. Forward Versus Back Thrusts in Accretionary Wedges: Effects of Rheology and Thickness of the Décollement Layer

    NASA Astrophysics Data System (ADS)

    Ito, Garrett; Olive, Jean-Arthur; Moore, Gregory; Gutscher, Marc-Andre; Weiss, Jonathan

    2016-04-01

    The mechanical processes that control whether major thrusts in accretionary wedges verge forward toward the foreland, versus backward toward the hinterland has long been a topic of debate. Whereas forethrusts are the most common major thrusts, the importance of the globally rare back thrusts has recently been highlighted given their prominence along the Cascadia margin off of the NW coast of North America as well as along the Andaman-Sumatra subduction zone, in the rupture area of the great 2004 earthquake. We address this problem using 2-D numerical models that use a finite-difference, particle-in-cell method with a viscoelastic-plastic rheology for simulating thrusting in accretionary wedges. Simulations of a weak frictional décollement confirm prior numerical and analogue modeling studies in that they predict lower wedge tapers and repeated sequences of doubly verging conjugate thrusts. A forward dipping backstop was shown in prior laboratory experiments to promote backthrusting, and our results confirm that backthrusting occurs near the backstop but as the wedge widens away from the backstop forethrusts become dominant. Other laboratory experimental studies have found that a non-brittle, viscously deforming décollement can promote backthrusting. Our numerical models show that if the viscosity of the décollement layer η is too high, such that the stress scale, ηU/H (where U is the convergence rate and H is the décollement layer thickness), is comparable to the frictional strength at the base, then forethrusts dominate. For ηU/H less than the basal frictional strength, doubly verging faults are prominent over a wide range of décollement layer thicknesses. Only for cases with relatively low ηU/H and décollement layer thicknesses H that are 25-33% of the thickness of the whole, incoming sediment layer do backthrusts dominate. Thus backthrusting appears to require unusual rheological properties of the deepest sediments, which is consistent with the rarity

  3. Lithostratigraphic analysis and geochemistry of a vitric spatter-bearing ignimbrite: the Quaternary Adeje Formation, Cañadas volcano, Tenerife

    NASA Astrophysics Data System (ADS)

    Dávila-Harris, P.; Ellis, B. S.; Branney, M. J.; Carrasco-Núñez, G.

    2013-06-01

    The 1.5-Ma Adeje Formation in SW Tenerife contains an ignimbrite sheet with remarkable textural and chemical complexity. A basal Plinian pumice-fall layer is overlain by a partly welded compound ignimbrite in which phonolitic pumice lapilli and dense obsidian spatter rags with irregular, fluidal-shaped margins are supported in a poorly sorted tuff matrix. The lower ignimbrite flow-unit contains accretionary lapilli in its upper part, overlain by an ash-pellet-bearing fallout layer from a co-ignimbrite plume. The upper ignimbrite flow-unit comprises a locally welded massive lapilli-tuff that grades up into lithic breccia containing juvenile obsidian blocks and both cognate and vent-derived lithic blocks. Geochemically, the Adeje Formation shows two distinct juvenile populations that relate to crystal-poor and crystal-rich magma types. Crystal-rich juvenile clasts contain multiple compositions of ilmenite and magnetite, and crystal aggregates of bytownite (An79-86). The varied assemblage of juvenile clasts reflects an eruptive style that may have involved rapid changes in magma chamber pressure associated with caldera collapse, and possibly the disruption of a lava lake. The Adeje eruption started with a Plinian explosive phase that rained ash and pumice lapilli across SW Tenerife; followed by pyroclastic fountaining feeding density currents with explosive ejecta of juvenile glassy material producing the coarse, spatter-bearing ignimbrite facies. A short pause between pyroclastic density currents is recorded by the co-ignimbrite ash and pellet-fall bed. The climactic phase of the eruption probably involved caldera subsidence as recorded by a widespread massive heterolithic breccia.

  4. Effects of fly ash particle size on strength of Portland cement fly ash mortars

    SciTech Connect

    Erdogdu, K.; Tuerker, P.

    1998-09-01

    Fly ashes do not have the same properties for different size fractions. It can be accepted that the effect of a fly ash on mortar strength is a combined effect of its size fractions. Therefore, it was concluded that by separating the size fractions and replacing cement with them, the combined bulk effect of a fly ash on strength can be better analyzed. In this study, different size fractions of fly ash were used to replace cement partially in standard compressive strength mortars. The authors attempted to interpret the strength of Portland cement-fly ash mortars in terms of the chemical, mineralogical, morphological, and physical properties of different fly ash size fractions used. Strengths of the mortars were compared at 2, 7, 28, and 90 days. Also strength of mortars with all-in ash (original ash containing all the fractions) were estimated by using strength of mortars with size fractions and the suitability of this estimation was discussed.

  5. LIFAC ash--strategies for management.

    PubMed

    Anthony, E J; Berry, E E; Blondin, J; Bulewicz, E M; Burwell, S

    2005-01-01

    LIFAC is a more recent addition to flue gas desulphurization methods for reducing sulphur emissions during coal combustion for the production of electricity. Ashes from the combustion of a low-sulphur lignite coal using LIFAC technology were used to evaluate different ash management strategies. The ashes, as produced and after treatment by the CERCHAR hydration process, were examined for their disposal characteristics and their utilization potential in concrete. They were also evaluated as underground disposal material using the AWDS process. PMID:15823742

  6. LIFAC ash--strategies for management.

    PubMed

    Anthony, E J; Berry, E E; Blondin, J; Bulewicz, E M; Burwell, S

    2005-01-01

    LIFAC is a more recent addition to flue gas desulphurization methods for reducing sulphur emissions during coal combustion for the production of electricity. Ashes from the combustion of a low-sulphur lignite coal using LIFAC technology were used to evaluate different ash management strategies. The ashes, as produced and after treatment by the CERCHAR hydration process, were examined for their disposal characteristics and their utilization potential in concrete. They were also evaluated as underground disposal material using the AWDS process.

  7. Toxicity of waste gasification bottom ash leachate.

    PubMed

    Sivula, Leena; Oikari, Aimo; Rintala, Jukka

    2012-06-01

    Toxicity of waste gasification bottom ash leachate from landfill lysimeters (112 m(3)) was studied over three years. The leachate of grate incineration bottom ash from a parallel setup was used as reference material. Three aquatic organisms (bioluminescent bacteria, green algae and water flea) were used to study acute toxicity. In addition, an ethoxyresorufin-O-deethylase (EROD) assay was performed with mouse hepatoma cells to indicate the presence of organic contaminants. Concentrations of 14 elements and 15 PAH compounds were determined to characterise leachate. Gasification ash leachate had a high pH (9.2-12.4) and assays with and without pH adjustment to neutral were used. Gasification ash leachate was acutely toxic (EC(50) 0.09-62 vol-%) in all assays except in the algae assay with pH adjustment. The gasification ash toxicity lasted the entire study period and was at maximum after two years of disposal both in water flea (EC(50) 0.09 vol-%) and in algae assays (EC(50) 7.5 vol-%). The grate ash leachate showed decreasing toxicity during the first two years of disposal in water flea and algae assays, which then tapered off. Both in the grate ash and in the gasification ash leachates EROD-activity increased during the first two years of disposal and then tapered off, the highest inductions were observed with the gasification ash leachate. The higher toxicity of the gasification ash leachate was probably related to direct and indirect effects of high pH and to lower levels of TOC and DOC compared to the grate ash leachate. The grate ash leachate toxicity was similar to that previously reported in literature, therefore, confirming that used setup was both comparable and reliable.

  8. Hazards Associated With Recent Popocatepetl Ash Emissions

    NASA Astrophysics Data System (ADS)

    Nieto, A.; Martin, A.; Espinasa-Pereña, R.; Ferres, D.

    2013-05-01

    Popocatepetl has been producing ash from small eruptions since 1994. Until 2012 about 650 small ash emissions have been recorded at the monitoring system of Popocatépetl Volcano. Ash consists mainly of glassy lithic clasts from the recent crater domes, plagioclase and pyroxene crystals, and in major eruptions, olivine and/or hornblende. Dome forming eruptions produced a fine white ash which covers the coarser ash. This fine ash consists of plagioclase, glass and cristobalite particles mostly under15 microns. During the recent crisis at Popocatépetl, April and May2012 ash fell on villages to the east and west of the volcano, reaching Mexico City (more than 20 million people) and Puebla (2 million people). In 14 cases the plumes had heights over 2 km, the largest on May 2 and 11 (3 and 4 km in height, respectively). Heavier ash fall occurred on April 13, 14, 20, and 23 and May 2, 3, 5, 11, 14, 23, 24 and 25. A database for ash fall was constructed from April 13 with field observations, reports emitted by the Centro Nacional de Comunicaciones (CENACOM), ash fall advisories received at CENAPRED and alerts from the Servicios a la Navegación en el Espacio Aéreo Mexicano (SENEAM). This aim of this database is to calculate areas affected by the ash and estimate the ash fall volume emitted by Popocatépetl in each of these events. Heavy ash fall from the May 8 to May 11 combined with reduced visibility due to fog forced to closure of the Puebla airport during various periods of time, for up to 13 hours. Domestic and international flights were cancelled. Ash eruptions have caused respiratory conditions in the state of Puebla, to the east of the volcano, since 1994 (Rojas et al, 2001), but because of the changing wind conditions in the summer mainly, some of these ash plumes go westward to towns in the State of Mexico and even Mexico City. Preliminary analyses of these eruptions indicate that some ash emissions produced increased respiratory noninfectious problems

  9. Spectrographic analysis of coal and coal ash

    USGS Publications Warehouse

    Hunter, R.G.; Headlee, A.J.W.

    1950-01-01

    Coal can be analyzed on the spectrograph for per cent ash and composition of ash in a matter of a few minutes, using the total energy method. The composition of the ash so determined can be used to calculate ash softening temperatures. This analysis can be made in sufficiently short a time to control tipple and washing operations for preparation of coal to meet specifications. This spectrographic method can be readily adapted to the analysis of rocks, minerals, and inorganic chemicals of all kinds.

  10. P-T-t deformation framework of an accretionary prism, southern New England Orogen, eastern Australia: Implications for blueschist exhumation and metamorphic switching

    NASA Astrophysics Data System (ADS)

    Phillips, G.; Hand, M.; Offler, R.

    2008-12-01

    The Tia Complex is located in the southern New England Orogen of eastern Australia and provides a detailed record of the structural-metamorphic evolution of an ancient accretionary prism. This record is characterized by six stages of deformation that were accompanied by a transition from moderate-pressure-low-temperature to low-pressure-high-temperature metamorphism. The composition of jadeitic pyroxene (subduction), magnesioriebeckite (exhumation), and actinolite (heating) have been used to model P-T conditions during these structural events, which range from P = 6.3-6.7 kbar and T = 320-350°C (subduction) to 1.5-2.0 kbar and 400-420°C (heating). On the basis of new structural and metamorphic data combined with preexisting age data, the evolution of this accretionary prism can be divided into two main stages: (1) blueschist formation and exhumation and (2) elevated heat flow and anatexis. To explain these features, a new model is presented that requires (1) wedge underthrusting and rear wedge extension associated with a stationary subduction hinge and (2) subduction hinge migration resulting in the relocation of the accretionary wedge onto the upper plate and heating during exposure to the mantle wedge. To explain the event chronology preserved in the Tia Complex, both extensional collapse and subduction hinge migration models are required.

  11. The effect of fault-bend folding on seismic velocity in the marginal ridge of accretionary prisms

    USGS Publications Warehouse

    Cai, Y.; Wang, Chun-Yong; Hwang, W.-t.; Cochrane, G.R.

    1995-01-01

    Fluid venting in accretionary prisms, which feeds chemosynthetic biological communities, occurs mostly on the marginal thrust ridge. New seismic data for the marginal ridge of the Cascadia prism show significantly lower velocity than that in the adjacent oceanic basin and place important constraints on the interpretations of why fluid venting occurs mostly on the marginal ridge. We employed a finite-element method to analyze a typical fault-bend folding model to explain the phenomenon. The fault in the model is simulated by contact elements. The elements are characterized not only by finite sliding along a slide line, but also by elastoplastic deformation. We present the results of a stress analysis which show that the marginal ridge is under subhorizontal extension and the frontal thrust is under compression. This state of stress favors the growth of tensile cracks in the marginal ridge, facilitates fluid flow and reduces seismic velocities therein; on the other hand, it may close fluid pathways along the frontal thrust and divert fluid flow to the marginal ridge. ?? 1995 Birkha??user Verlag.

  12. Major and trace element geochemistry and Os isotopic composition of metalliferous umbers from the Late Cretaceous Japanese accretionary complex

    NASA Astrophysics Data System (ADS)

    Kato, Yasuhiro; Fujinaga, Koichiro; Suzuki, Katsuhiko

    2005-07-01

    Metalliferous umbers and red shales occur as unique products of the Kula-Pacific ridge-forearc collision in the Late Cretaceous Shimanto Supergroup, an accretionary complex in Japan. These umbers are closely associated with greenstones of mid-ocean ridge basalt (MORB) origin and are regarded as hydrothermal metalliferous precipitates related to MOR-type volcanism. The umbers and red shales were deposited in the trench area where both terrigenous detritus from land and hydrothermal metalliferous particulates from a MOR were supplied simultaneously. Besides a predominance of Fe and Mn, the umbers exhibit remarkable enrichments in P, V, Co, Ni, Zn, Y, Mo, rare earth elements (REEs), and Os relative to continental crustal abundances. The X/Fe (X = Mn, P, V, Co, Ni, Zn, Y, and REEs) ratios and PAAS-normalized REE patterns of the umbers are very similar to those of modern hydrothermal plume fallout precipitates deposited on flanks of MOR. This indicates that the umbers preserve primary geochemical signatures of hydrothermal metalliferous sediments that scavenged seawater-derived elements and thus can be used as a proxy for Late Cretaceous seawater. The marine 187Os/188Os ratios reconstructed from the late Maastrichtian umbers range from 0.42 to 0.56 and are very consistent with recent data obtained from the Pacific and Atlantic pelagic carbonates that record an abrupt decline from 0.55 to 0.4 during the period between 67.0 Ma and 65.7 Ma.

  13. First results from the NEAREST-SEIS deep seismic cruise across the Gulf of Cadiz accretionary wedge

    NASA Astrophysics Data System (ADS)

    Gailler, A.; Gutscher, M.-A.; Graindorge, D.; Sallarès, V.; Bartolome, R.; Gracia, E.

    2009-04-01

    The Gulf of Cadiz lies offshore of Southwest Iberia and Northwest Morocco, bounded to the West by the Azores-Gibraltar transform and to the East by the Betic-Rif mountain belt. The region is famous for the great 1755 Lisbon earthquake and tsunami. Here the plate boundary between Africa and Eurasia is complex, marked by a broad region of deformation spanning about 200 km in a north-south direction. One of the most striking structures characterizing the Gulf of Cadiz is the presence of a thick tectonically deformed sedimentary wedge, which is interpreted as an accretionary wedge formed by the W to SW migration of the Rif-Betic block. Two types of geodynamic models have been proposed to explain the recent tectonics and formation of this region: those invoking delamination of continental lithosphere beneath the Betic-Rif Alboran Sea region, and those favouring subduction of oceanic lithosphere, with associated roll-back. Numerous marine geophysical surveys were performed in the Gulf of Cadiz area during the last years, many as part of the NEAREST European project. Multi-beam bathymetry and multi-channel seismic (MCS) data were acquired, which help constrain the upper crustal structures. Deep structural maps demonstrate that sediment thicknesses in the central Gulf of Cadiz (beneath the accretionary wedge) reach a maximum of 12-13 km. Additional wide-angle seismic records acquired during the SISMAR experiment (2001) testify to the difficulty of even low-frequency waves to penetrate below this thick sedimentary body. Nevertheless, from the resulting models a 7-to-10-km thick basement is inferred beneath the western and central Gulf, which forms a roughly E-W oriented trough between the thicker (20-30 km) continental crust of SW Iberia and NW Morocco. During the NEAREST-SEIS cruise on the B/O Hesperides (nov. 2008), two wide-angle seismic lines were acquired in the Gulf of Cadiz area using a seismic source composed of seven 1500LL Bolt airguns (4520 in3), shot at 90 s

  14. The relationship between mud volcanoes, petroleum migration and accretionary prisms: Lessons from the Caucasus, the Australian margin and Venezuela

    SciTech Connect

    Ware, P.

    1996-08-01

    Mud volcanoes have been widely documented in areas of overpressure where explosive expansion of trapped methane has occurred during argillokinesis. In an area with high sedimentation rate, such as the Gulf of Mexico, there may be no time for fine-grained sediment to de-water before being covered by impermeable material. In an accretionary wedge this process is complicated by overthrusting of off-scraped material which increases the overburden pressure and provides many more avenues for the migration of fluids through the system. In some cases, such as is seen in the Caribbean, the fluids may escape directly to the surface (or seabottom) through high permeability beds. When this happens there may be no diapirism. In other cases, such as in Venezuela, the forearc may be the site of rapid, laterally-derived, sedimentation, and fluids from the overthrusted rocks may be forced to escape through several kilometers of recent deltaic sediments. Since these fluids may include petroleum, this has obvious exploration potential. If there are no suitable reservoir rocks, such as in Timor, there may be no commercial accumulations. However, many giant fields are associated, world-wide, with mud volcanoes, such as those in Azerbaijan.

  15. Relationship between tectonics, argilokinetic structures, and environmental patterns at the south boundary of the Barbados accretionary prism

    SciTech Connect

    Griboulard, R.; Bobier, C.; Faugeres, J.C.; Gonthier, E.

    1993-02-01

    Recent studies have been carried out on limited sectors of the South Barbados accretionary prism. They are supported by SeaBeam map analysis, high resolution seismic data, time-lapse and video camera tracks, numerous cores and Side Scan Sonar data. The analysis of these data point out numerous evidences of an active and present tectonic activity on the southern part of this domain. The development of very large indurate sea-bottoms on which deep-sea communities frequently occur and where we can observe some [open quotes]sigmoidal[close quotes] features and network of conjugate fractures which suggest the presence of shear deformation zone. In addition, tracks of important and probably deep faults extend across both soft and indurated bottom sediments. The regional morphological anomalies are comparable to analogical deformation model for a thick cover sticking out of its sub-stratum and the tectonic activity is closely associated to the presence of deep dysharmonic levels which control, obviously, an important clay-diapirism. This is an effect of both the structural location of this region, at the junction of three lithospheric plates (Caribbean, Atlantic, and South-American) and paleogeographical and sedimentological changes since Neogene time, with the very important terrigeneous supplies coming from the Orinoco River. Consequently, the main deformations that we observed in this region are rather under influence of shearing and transpressive than compressive movements.

  16. The 50 Ma granodiorite of the eastern Gulf of Alaska - Melting in an accretionary prism in the forearc

    NASA Astrophysics Data System (ADS)

    Barker, Fred; Farmer, G. L.; Ayuso, R. A.; Plafker, George; Lull, J. S.

    1992-05-01

    The paper addresses the generation of granitic rocks by the melting of flyschoid sediments in an accretionary prism as part of an investigation of 50-Ma silicic igneous rocks in the Gulf of Alaska, near Cordova, Alaska. Three intrusive bodies exhibiting a range of chemical and initial isotopic compositions were chosen: the McKinley Peak, Rude River, and Sheep Bay plutons. The present chemical data, modeling, and comparison with melting experiments of graywacke by Conrad et al. (1988) indicate that the granodiorite originated by large fractions (65-90 percent) of melting of the Orca Group graywacke and argillite. Plagioclase, pyroxene, and biotite were residual to melting at about 850-950 C and at low H2O activities. It is suggested that the distinct chemical and isotopic compositions of the McKinley Peak pluton result from variations in the character of the flysch at depth in the prism, rather than from mixing between melts of the flysch and mafic magmas injected into the prism itself.

  17. Olistostromes are the Source of Melange in Diapirs in the Cascadia-Olympics Accretionary Wedge , NW USA

    NASA Astrophysics Data System (ADS)

    Cowan, D. S.; Brandon, M. T.

    2011-12-01

    Diapirs consisting of block-in-matrix mélange are common in the ocean-ward part of the active Cascadia-Olympics wedge. Some of these bodies and similar Neogene mélanges ["Hoh mélange"] have been interpreted as having originated in shear zones related to accretion as oceanic crust of the Juan de Fuca plate was thrust beneath the wedge. However, this interpretation is untenable. The Hoh mélange contains fragments and blocks, ranging from centimeters to kilometers in size, of basalt. The chemistry of the basalt, and the microfossils in associated mudstone, prove that the basalt is Eocene: these basalts were derived from the Crescent Formation, not the much younger oceanic crust of the Juan de Fuca plate. The Crescent basalts originally formed the lid beneath which the Cascadia-Olympics wedge of sediments was underplated. Much of the lid has been eroded, but in Miocene time it extended to the coast and contributed fragments and blocks to muddy debris flows, which were deposited as olistostromes on the subducting Juan de Fuca plate. Younger sediments buried the olistostromes, which became overpressured and mobilized as mobile masses that have intruded as diapirs and anticlinal ridges. Analogous diapiric bodies, in the broad sense, are present in other active accretionary wedges, such as the in the Lesser Antilles.

  18. Fluid flow in and around a mud volcano field seaward of the Barbados accretionary wedge: Results from Manon cruise

    NASA Astrophysics Data System (ADS)

    Henry, Pierre; Le Pichon, Xavier; Lallemant, Siegfried; Lance, Sophie; Martin, Jonathan B.; Foucher, Jean-Paul; Fiala-MéDioni, Aline; Rostek, Frauke; Guilhaumou, Nicole; Pranal, Vincent; Castrec, Maryse

    1996-09-01

    A field of mud diapirs and mud volcanoes situated in the Barbados trench at 13°50'N and extending along an old oceanic fracture zone (Mercurus) was investigated during the Manon cruise using both surface ship and Nautile submersible sampling and measurements. The entire zone from 13°50'N up to 14°20'N has an anomalously high heat flow which implies that fluids are drained into it from a segment of the accretionary wedge a few hundred kilometers wide. Two structures interpreted as diatremes, Atalante and Cyclops, expell large amounts of water and methane. We propose that they were formed from the release of a light fluid when gas hydrates were dissociated in the sediment as the result of the circulation of warm fluid in the area. However they expell only a small fraction of the incoming fluid, implying that disperse flow is the dominant mode of expulsion in this area. The chemoautotrophic communities on the surface of the structures rely mostly on sulfides. Submersible observations, temperature measurements in the sediment, and the chemistry of the pore fluid indicate that convection of seawater occurs within the first few meters of sediment through high-permeability channels, such as cemented carbonate conduits. We propose that this convection is driven by the density difference between the pore fluid and seawater, but fresh water released by the dissolution of shallow hydrates may also contribute. This shallow convection may be a frequent process in cold seep environments.

  19. Treatment of fly ash for use in concrete

    DOEpatents

    Boxley, Chett

    2012-05-15

    A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with a quantity of spray dryer ash (SDA) and water to initiate a geopolymerization reaction and form a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 40%, and in some cases less than 20%, of the foam index of the untreated fly ash. An optional alkaline activator may be mixed with the fly ash and SDA to facilitate the geopolymerization reaction. The alkaline activator may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

  20. 10 Risk to Ash from Emerald Ash Borer: Can Biological Control Prevent the Loss of Ash Stands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ash trees were once relatively free of serious, major diseases and insect pests in North America until the arrival of EAB, which was first detected in North America in Michigan in 2002. As of February 2014, EAB had been detected in 22 U.S. states and two Canadian provinces, killing millions of ash ...

  1. Changes of the ash structure

    NASA Astrophysics Data System (ADS)

    Peer, Václav; Friedel, Pavel; Janša, Jan

    2016-06-01

    The aim of the article is to appraisal of the changes in the structure of the ash due to the addition of compounds capable of the eutectics composition change. For the transformation were used limestone and dolomite dosed in amounts of 2, 5 and 10 wt.% with pellets of spruce wood, willow wood and refused derived fuel. Combustion temperatures of the mixtures were adjusted according to the temperatures reached during the using of fuels in power plants, i.e. 900, 1000, 1100 and 1200 °C.

  2. Structural controls on the development of submarine channel/fan systems since the Pleistocene in the accretionary wedge off SW Taiwan

    NASA Astrophysics Data System (ADS)

    Shen, Kang-Nien; Tien-Shun Lin, Andrew; Lin, Che-Chuan; Liu, Char-Shine; Wang, Yunshuen

    2016-04-01

    The accretionary wedge off SW Taiwan is the result of incipient arc-continent collision between the Luzon volcanic arc and the northern rifted margin of the South China Sea (SCS). Dynamic interactions of thrusting, folding and a rigorous sediment supply from the Taiwan mountain belts have resulted in two arrays of canyons/channels and slope-fan systems in the accretionary wedge. The Penghu canyon/fan system lies in the lower wedge and near the northern rifted margin of the SCS. The Penghu canyon is a river-fed canyon and receives sediments from southern Taiwan and SE China during eustatic lowstands. It becomes detached from river inputs during eustatic highstands as it is in the present-day. The Gaoping canyon/fan system in the south traverses both the upper slope and lower slope domains of the accretionary wedge. This system is a river-fed system during a full eustatic cycle and it drains sediments from the onshore Gaoping River. We interpreted multiple grids of multichannel seismic reflection data of MCS994, MCS1000-6, MCS1014, MCS1046 collected onboard Ocean Research I during 2012 April to 2013 August to map out thrust/fold structures and channel/fan systems in the study area. Seismic facies analyses were performed on seismic sections and key stratal surfaces of base of Pliocene and base of Pleistocene are correlated from boreholes drilled in the shelf of the northern SCS margin. Our results show that the upper Gaoping Canyon has been confined by structural ridges with limited switching of canyon courses, whereas the lower Gaoping canyon/fan system has been developed on lower slope with channel/levee deposition in multiple slope fans since early Pleistocene. Pleistocene lateral aggrading channel-and-levee systems are especially evident near the modern canyon course in the lower slope. The Penghu can/fan system in the lower accretionary wedge is also evident by seismic facies showing channel cut-and-fill, channel abandonment and channel-and-levee systems. This

  3. Controls on accretion of flysch and melange belts at convergent margins: evidence from the Chugach Bay thrust and Iceworm melange, Chugach accretionary wedge, Alaska

    USGS Publications Warehouse

    Kusky, T.M.; Bradley, D.C.; Haeussler, P.J.; Karl, S.

    1997-01-01

    Controls on accretion of flysch and melange terranes at convergent margins are poorly understood. Southern Alaska's Chugach terrane forms the outboard accretionary margin of the Wrangellia composite terrane, and consists of two major lithotectonic units, including Triassic-Cretaceous melange of the McHugh Complex and Late Cretaceous flysch of the Valdez Group. The contact between the McHugh Complex and the Valdez Group on the Kenai Peninsula is a tectonic boundary between chaotically deformed melange of argillite, chert, greenstone, and graywacke of the McHugh Complex and a less chaotically deformed melange of argillite and graywacke of the Valdez Group. We assign the latter to a new, informal unit of formational rank, the Iceworm melange, and interpret it as a contractional fault zone (Chugach Bay thrust) along which the Valdez Group was emplaced beneath the McHugh Complex. The McHugh Complex had already been deformed and metamorphosed to prehnite-pumpellyite facies prior to formation of the Iceworm melange. The Chugach Bay thrust formed between 75 and 55 Ma, as shown by Campanian-Maastrichtian depositional ages of the Valdez Group, and fault-related fabrics in the Iceworm melange that are cut by Paleocene dikes. Motion along the Chugach Bay thrust thus followed Middle to Late Cretaceous collision (circa 90-100 Ma) of the Wrangellia composite terrane with North America. Collision related uplift and erosion of mountains in British Columbia formed a submarine fan on the Farallon plate, and we suggest that attempted subduction of this fan dramatically changed the subduction/accretion style within the Chugach accretionary wedge. We propose a model in which subduction of thinly sedimented plates concentrates shear strains in a narrow zone, generating melanges like the McHugh in accretionary complexes. Subduction of thickly sedimented plates allows wider distribution of shear strains to accommodate plate convergence, generating a more coherent accretionary style

  4. The development of folds and cleavages in slate belts by underplating in accretionary complexes: A comparison of the Kodiak Formation, Alaska and the Calaveras Complex, California

    NASA Astrophysics Data System (ADS)

    Paterson, Scott R.; Sample, James C.

    1988-08-01

    The development of folds and cleavages in slate and graywacke belts is commonly attributed to arc-continent or continent-continent collisions. However, the Kodiak Formation of southern Alaska and the Calaveras Complex of the western Sierra Nevada, California, are two slate and graywacke belts in which folds and slaty cleavages developed during simple underthrusting and underplating within accretionary wedges. The Maastrichtian Kodiak Formation is composed dominantly of coherent turbidites but includes lesser pebbly mudstone, minor conglomerate, and rare chert. The Kodiak Formation is part of a large accretionary complex that youngs in age seaward, but bedding tops generally show landward younging. A progression of structures has been determined by crosscutting relationships and includes (1) syndeformational depositional features; (2) broken formation; (3) slaty cleavage, folds, and thrust faults; (4) crenulations and crenulation cleavage; (5) late brittle thrust faults; and (6) right-lateral strike-slip faults. Broken formation, slaty cleavage, thrust faults, and folds developed during underthrusting and underplating within an accretionary wedge. Crenulations and brittle thrust faults are related to subsequent intrawedge shortening. Based on peak metamorphism in the uppermost zeolite to prehnite-pumpellyite facies, underplating occurred at a minimum depth of 10 km. The Calaveras Complex is composed of argillite, chert, graywacke, pebbly mudstone, limestone, and volcanic rocks. Its age of deposition has a maximum range from Permian to Early Jurassic. Overall, the unit appears to young westward, but local facing indicators show eastward younging of individual blocks. The sequence of structures developed in the Calaveras Complex is (1) syn-depositional olistostromes; (2) broken formation; (3) slaty cleavage, folds, and thrust faults; and (4) younger Jura-Triassic folds and crenulation cleavages. Broken formation and slaty cleavage developed during underthrusting and

  5. Accretionary Complexes: Recorders of Plate Tectonism and Environmental Conditions Through Time on Earth and Possibly Those Early Noachian (Hadean-equivalent) in Age on Mars

    NASA Astrophysics Data System (ADS)

    Dohm, J. M.; Maruyama, S.; Miyamoto, H.; Viviano-Beck, C. E.; Anderson, R. C.

    2014-12-01

    On Earth, highlighted in Japan, North America, Europe, and Greenland, accretionary complexes comprehensively record information compiled while the oceanic crust is en route from the mid-oceanic ridge to the subduction zone, spanning hundreds of millions of years. At the zone, oceanic crustal materials are stacked along thrust faults and/or subducted to be eventually recycled into the mantle. The surviving accretionary-complex materials include Ocean Plate Stratigraphy (OPS). The ideal succession of the OPS (from oldest to youngest) is mid-ocean ridge basalt, pelagic sediment including radiolarian chert, hemipelagic sediment including siliceous shale, and trench turbidite deposits. Therefore, accretionary complexes often record diverse environmental conditions from deep- to shallow-marine environments, including those perturbed by magmatic, impact, and possibly extrasolar events. Stratigraphic, impact-crater, paleotectonic, and magnetic-anomaly information point to Early Noachian (Hadean-equivalent) Martian geologic terrains; they are extremely ancient environmental records compared to those destroyed on Earth due to differences in planetary mass and evolutional states. Such record a dynamic phase of the evolution of Mars, including interacting ocean, landmass, and atmosphere, as well as possible plate tectonism during an operating dynamo. A candidate accretionary complex and nearby outcrops of steeply dipping beds comprising olistostrome-like blocks, nearby and in the Claritas rise, respectively, may be key evidence of major crustal shortening related to plate tectonism, in addition to being extremely ancient environmental records. Claritas rise is a rugged promontory about 250 km across, which forms the northwest part of an extremely ancient and large mountain range, Thaumasia highlands, with a length nearing 2,400 km, or approximating that of the Himalayas. Future investigation of the ancient Martian basement, which includes geochemical analyses for possible OPS

  6. Mazama ash in the northeastern pacific.

    PubMed

    Nelson, C H; Kulm, L D; Carlson, P R; Duncan, J R

    1968-07-01

    Volcanic glass in marine sediments off Oregon and Washington correlates with continental deposits of Mount Mazama ash by stratigraphic position, refractive index, and radiocarbon dating. Ash deposited in the abyssal regions by turbidity currents is used for tracing of the dispersal routes of postglacial sediments and for evaluation of marine sedimentary processes.

  7. Energy efficient continuous flow ash lockhopper

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor); Suitor, Jerry W. (Inventor); Dubis, David (Inventor)

    1989-01-01

    The invention relates to an energy efficient continuous flow ash lockhopper, or other lockhopper for reactor product or byproduct. The invention includes an ash hopper at the outlet of a high temperature, high pressure reactor vessel containing heated high pressure gas, a fluidics control chamber having an input port connected to the ash hopper's output port and an output port connected to the input port of a pressure letdown means, and a control fluid supply for regulating the pressure in the control chamber to be equal to or greater than the internal gas pressure of the reactor vessel, whereby the reactor gas is contained while ash is permitted to continuously flow from the ash hopper's output port, impelled by gravity. The main novelty resides in the use of a control chamber to so control pressure under the lockhopper that gases will not exit from the reactor vessel, and to also regulate the ash flow rate. There is also novelty in the design of the ash lockhopper shown in two figures. The novelty there is the use of annular passages of progressively greater diameter, and rotating the center parts on a shaft, with the center part of each slightly offset from adjacent ones to better assure ash flow through the opening.

  8. Mazama ash in the Northeastern Pacific

    USGS Publications Warehouse

    Nelson, C.H.; Kulm, L.D.; Carlson, P.R.; Duncan, J.R.

    1968-01-01

    Volcanic glass in marine sediments off Oregon and Washington correlates with continental deposits of Mount Mazama ash by stratigraphic position, refractive index, and radiocarbon dating. Ash deposited in the abyssal regions by turbidity currents is used for tracing of the dispersal routes of postglacial sediments and for evaluation of marine sedimentary processes.

  9. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Ash pans. 230.69 Section 230.69 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans §...

  10. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Ash pans. 230.69 Section 230.69 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans §...

  11. 49 CFR 230.69 - Ash pans.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Ash pans. 230.69 Section 230.69 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Ash Pans §...

  12. Construction procedures using self hardening fly ash

    NASA Astrophysics Data System (ADS)

    Thornton, S. I.; Parker, D. G.

    1980-07-01

    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  13. Geotechnical characterization of some Indian fly ashes

    SciTech Connect

    Das, S.K.; Yudhbir

    2005-10-01

    This paper reports the findings of experimental studies with regard to some common engineering properties (e.g., grain size, specific gravity, compaction characteristics, and unconfined compression strength) of both low and high calcium fly ashes, to evaluate their suitability as embankment materials and reclamation fills. In addition, morphology, chemistry, and mineralogy of fly ashes are studied using scanning electron microscope, electron dispersive x-ray analyzer, x-ray diffractometer, and infrared absorption spectroscopy. In high calcium fly ash, mineralogical and chemical differences are observed for particles, {gt}75 {mu} m and the particles of {lt} 45 {mu} m size. The mode and duration of curing significantly affect the strength and stress-strain behavior of fly ashes. The geotechnical properties of fly ash are governed by factors like lime content (CaO), iron content (Fe{sub 2}O{sub 3}) and loss on ignition. The distinct difference between self-hardening and pozzolanic reactivity has been emphasized.

  14. Properties and Leachability of Self-Compacting Concrete Incorporated with Fly Ash and Bottom Ash

    NASA Astrophysics Data System (ADS)

    Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Jamaluddin, Norwati; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    The process of combustion in coal-fired power plant generates ashes, namely fly ash and bottom ash. Besides, coal ash produced from coal combustion contains heavy metals within their compositions. These metals are toxic to the environment as well as to human health. Fortunately, treatment methods are available for these ashes, and the use of fly ash and bottom ash in the concrete mix is one of the few. Therefore, an experimental program was carried out to study the properties and determine the leachability of selfcompacting concrete incorporated with fly ash and bottom ash. For experimental study, self-compacting concrete was produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a replacement for sand with the ratios of 10%, 20%, and 30% respectively. The fresh properties tests conducted were slump flow, t500, sieve segregation and J-ring. Meanwhile for the hardened properties, density, compressive strength and water absorption test were performed. The samples were then crushed to be extracted using Toxicity Characteristic Leaching Procedure and heavy metals content within the samples were identified accordingly using Atomic Absorption Spectrometry. The results demonstrated that both fresh and hardened properties were qualified to categorize as self-compacting concrete. Improvements in compressive strength were observed, and densities for all the samples were identified as a normal weight concrete with ranges between 2000 kg/m3 to 2600 kg/m3. Other than that, it was found that incorporation up to 30% of the ashes was safe as the leached heavy metals concentration did not exceed the regulatory levels, except for arsenic. In conclusion, this study will serve as a reference which suggests that fly ash and bottom ash are widely applicable in concrete technology, and its incorporation in self-compacting concrete constitutes a potential means of adding value to appropriate mix and design.

  15. Investigation on Leaching Behaviour of Fly Ash and Bottom Ash Replacement in Self-Compacting Concrete

    NASA Astrophysics Data System (ADS)

    Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    Fly ash and bottom ash are some of the waste generated by coal-fired power plants, which contains large quantities of toxic and heavy metals. In recent years, many researchers have been interested in studying on the properties of self-compacting concrete incorporated with fly ash and bottom ash but there was very limited research from the combination of fly ash and bottom ash towards the environmental needs. Therefore, this research was focused on investigating the leachability of heavy metals of SCC incorporated with fly ash and bottom ash by using Toxicity Characteristic Leaching Procedure, Synthetic Precipitation Leaching Procedure and Static Leaching Test. The samples obtained from the coal-fired power plant located at Peninsula, Malaysia. In this study, the potential heavy metals leached out from SCC that is produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a substitute for sand with the ratios from 10% to 30% respectively were designated and cast. There are eight heavy metals of concern such as As, Cr, Pb, Zn, Cu, Ni, Mn and Fe. The results indicated that most of the heavy metals leached below the permissible limits from the United States Environmental Protection Agency and World Health Organization limit for drinking water. As a conclusion, the minimum leaching of the heavy metals from the incorporation of fly ash and bottom ash in self-compacting concrete was found in 20% of fly ash and 20% of bottom ash replacement. The results also indicate that this incorporation could minimize the potential of environmental problems.

  16. Differential response in foliar chemistry of three ash species to emerald ash borer adult feeding.

    PubMed

    Chen, Yigen; Whitehill, Justin G A; Bonello, Pierluigi; Poland, Therese M

    2011-01-01

    The emerald ash borer (EAB; Agrilus planipennis Fairmaire; Coleoptera: Buprestidae), is an exotic wood-boring beetle that has been threatening North American ash (Fraxinus spp.) resources since its discovery in Michigan and Ontario in 2002. In this study, we investigated the phytochemical responses of the three most common North American ash species (black, green, and white ash) in northeastern USA to EAB adult feeding. Black ash was the least responsive to EAB adult feeding in terms of the induction of volatile compounds, and levels of only two (indole and benzyl cyanide) of the 11 compounds studied increased. In green ash, levels of two [(E)-β-ocimene and indole] of the 11 volatile compounds studied were elevated, while the levels of two green leaf volatiles [hexanal and (E)-2-hexenal] decreased. White ash showed the greatest response with an increase in levels of seven of the 11 compounds studied. Qualitative differences among ash species were detected. Among the phenolic compounds detected, ligustroside was the only one detected in all three species. Oleuropein aglycone and 2 unidentified compounds were found only in black ash; coumaroylquinic acid and feruloylquinic acid were detected only in green ash; and verbascoside hexoside was detected only in white ash. EAB adult feeding did not elicit or decrease concentrations of any selected individual phenolic compounds. However, although levels of total phenolics from black and green ash foliage were not affected by EAB adult feeding, they decreased significantly in white ash. EAB adult feeding elevated chymotrypsin inhibitors in black ash. The possible ecological implications of these findings are discussed.

  17. Model for upper atmospheric aggregation of ash following hypervelocity impact events

    NASA Astrophysics Data System (ADS)

    Huber, Matthew; Artemieva, Natasha

    2014-05-01

    Introduction: Accretionary lapilli (AL) have been found in hypervelocity impact crater ejecta deposits and are similar to volcanically produced AL [1]. The initial conditions of ejection from an impact crater are vastly different than ejection from a volcano, particularly regarding the mass of ejecta and the velocity of ejection. Thus, some models of AL formation may not apply to impact ejecta. We propose an upper atmospheric aggregation model. A numerical model is herein described Numerical model: Re-entry is modeled using the 3D hydrocode SOVA [2], using mainly its "dusty flow" subroutines. Particles are treated as solid non-deformable; they move through the atmosphere and exchange momentum and energy. Radiative, conductive, and convective heat transfer are included. Details of the procedure may be found in [2]. Initial mass flux of ejecta, velocities, and re-entry angles are derived from crater-forming models. The power law SFD N>m~m-b is used with the exponent b of 0.8 and 0.9. The largest fragment for a given distance can be deduced from observations. The smallest fragments are ~10 µm in diameter. Results: During re-entry, particles decelerate due to drag, heating the atmosphere, and the atmospheric gas heats particles via conduction, convection, and radiative transfer. Additionally, shock waves are generated. Intensity of these processes depends on the total mass and velocity of ejecta, but also on the ejecta SFD. Particles of varying sizes were modeled. Large particles penetrate to low altitudes, maintaining temperature. Small particles decelerate at high altitudes, have elevated temperatures, and heat the atmosphere to T> 600 K. These particles can release water from pores or, in some cases, from mineral structures. Cold particles entering later may be coated by this water, permitting aggregation and pushing other particles to lower altitudes. Substantial mixing of particles at temperatures and densities suitable for AL formation remains as long as ejecta

  18. Treatment of fly ash for use in concrete

    DOEpatents

    Boxley, Chett; Akash, Akash; Zhao, Qiang

    2013-01-08

    A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with an activator solution sufficient to initiate a geopolymerization reaction and for a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 35% of the foam index of the untreated fly ash, and in some cases less than 10% of the foam index of the untreated fly ash. The activator solution may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

  19. Treatment of fly ash for use in concrete

    DOEpatents

    Boxley, Chett; Akash, Akash; Zhao, Qiang

    2012-05-08

    A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with an activator solution sufficient to initiate a geopolymerization reaction and for a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 35% of the foam index of the untreated fly ash, and in some cases less than 10% of the foam index of the untreated fly ash. The activator solution may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

  20. Laboratory Studies of Ice Nucleation on Volcanic Ash

    NASA Astrophysics Data System (ADS)

    Tolbert, M. A.; Schill, G. P.; Genareau, K. D.

    2014-12-01

    Ice nucleation on volcanic ash controls both ash aggregation and cloud glaciation, which affect human respiratory health, atmospheric transport, and global climate. We have performed laboratory studies of the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman Microscopy coupled to an environmental cell. Ash from the Fuego (Basaltic Ash, Guatemala), Soufriere Hills (Andesetic Ash, Montserrat), and Taupo (Rhyolitic Ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. We find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice at ice saturation ratios of 1.05 ± 0.1. For immersion freezing, however, only the Taupo ash exhibited efficient heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

  1. Causes and consequences of the great strength variability among soft Nankai accretionary prism sediments from offshore SW-Japan

    NASA Astrophysics Data System (ADS)

    Stipp, Michael; Schumann, Kai; Leiss, Bernd; Ullemeyer, Klaus

    2014-05-01

    The Nankai Trough Seismogenic Zone Experiment of the International Ocean Discovery Program (IODP) is the very first attempt to drill into the seismogenic part of a subduction zone. Offshore SW-Japan the oceanic Philippine sea plate is subducted beneath the continental Eurasian plate causing earthquakes of magnitude 8.0 to 8.5 and related tsunamis with a recurrence rate of 80-100 years. For the tsunamigenic potential of the forearc slope and accreted sediments their mechanical strength, composition and fabrics have been investigated. 19 drill core samples of IODP Expeditions 315, 316 and 333 were experimentally deformed in a triaxial cell under consolidated and undrained conditions at confining pressures of 400-1000 kPa, room temperature, axial shortening rates of 0.01-9.0 mm/min, and up to an axial strain of ˜64% (Stipp et al., 2013). With respect to the mechanical behavior, two distinct sample groups could be distinguished. Weak samples from the upper and middle forearc slope of the accretionary prism show a deviatoric peak stress after only a few percent strain (< 10%) and a continuous stress decrease after a maximum combined with a continuous increase in pore pressure. Strong samples from the accretionary prism toe display a constant residual stress at maximum level or even a continuous stress increase together with a decrease in pore pressure towards high strain (Stipp et al., 2013). Synchrotron texture and composition analysis of the experimentally deformed and undeformed samples using the Rietveld refinement program MAUD indicates an increasing strength of the illite and kaolinite textures with increasing depth down to 523 m below sea floor corresponding to a preferred mineral alignment due to compaction. Experimentally deformed samples have generally stronger textures than related undeformed core samples and they show also increasing strength of the illite and kaolinite textures with increasing axial strain. Mechanically weak samples have a bulk clay plus

  2. A lithium isotopic study of sub-greenschist to greenschist facies metamorphism in an accretionary prism, New Zealand

    NASA Astrophysics Data System (ADS)

    Qiu, Lin; Rudnick, Roberta L.; Ague, Jay J.; McDonough, William F.

    2011-01-01

    To investigate the behavior of Li during low-grade metamorphism and fluid flux in an accretionary prism we measured the Li concentrations ([Li]) and isotopic compositions (δ7Li) of sub-greenschist and greenschist-facies Otago Schist composites, as well as cross-cutting quartz veins, which are interpreted to have precipitated from slab-derived fluids. The average [Li] of sub-greenschist facies composites (41 ± 13 μg/g, 2σ) is statistically distinct (97% confidence level, student t test) to that of greenschist facies composites (34 ± 9 μg/g, 2σ), which have experienced mass addition of silica in the form of quartz veins having [Li] between 0.4-2.3 μg/g. A linear regression of the correlation between [Li] and calculated mass additions suggests that the depletion of [Li] in greenschist facies composites is due to both dilution from the addition of the quartz veins, as well as metamorphic dehydration. The [Li] of both groups of composites correlates with their CIA (Chemical Index of Alteration) values (50-58), which are low, consistent with the inferred graywacke protolith of the Otago Schist. The δ7Li of sub-greenschist and greenschist facies composites are remarkably constant, with an average δ7Li of 0.2 ± 1.7 (2σ) and -0.5 ± 1.9 (2σ), respectively, and comparable to that of the average upper continental crust. Thus, metamorphism has had no discernable effect on δ7Li in these samples. The Li isotopic signature of the schists is similar to that seen in pelitic sedimentary rocks and likely reflects the δ7Li of the protoliths. The surprisingly light δ7Li of the quartz veins (-2.8 to -1.4) likely records kinetic fractionation associated with Li ingress into the veins from surrounding wallrock. An isotopic equilibrium fluid flow model indicates that: 1) if the [Li] of slab-derived fluids is less than a few μg/g, the δ7Li of the overlying lithologies (i.e., the schists) is not significantly influenced by the fluid flux, regardless of the δ7Li of the

  3. Seismic structure of the southern Cascadia subduction zone and accretionary prism north of the Mendocino triple junction

    USGS Publications Warehouse

    Gulick, S.P.S.; Meltzer, A.M.; Clarke, S.H.

    1998-01-01

    Four multichannel-seismic reflection profiles, collected as part of the Mendocino triple junction seismic experiment, image the toe of the southern Cascadia accretionary prism. Today, 250-600 m of sediment is subducting with the Gorda plate, and 1500-3200 m is accreting to the northern California margin. Faults imaged west and east of the deformation front show mixed structural vergence. A north-south trending, 20 km long portion of the central margin is landward vergent for the outer 6-8 km of the toe of the prism. This region of landward vergence exhibits no frontal thrust, is unusually steep and narrow, and is likely caused by a seaward-dipping backstop close to the deformation front. The lack of margin-wide preferred seaward vergence and wedge-taper analysis suggests the prism has low basal shear stress. The three southern lines image wedge-shaped fragments of oceanic crust 1.1-7.3 km in width and 250-700 m thick near the deformation front. These wedges suggest shortening and thickening of the upper oceanic crust. Discontinuities in the seafloor west of the prism provide evidence for mass wasting in the form of slump blocks and debris fans. The southernmost profile extends 75 km west of the prism imaging numerous faults that offset both the Gorda basin oceanic crust and overlying sediments. These high-angle faults, bounding basement highs, are interpreted as strike-slip faults reactivating structures originally formed at the spreading ridge. Northeast or northwest trending strike-slip faults within the basin are consistent with published focal mechanism solutions and are likely caused by north-south Gorda-Pacific plate convergence. Copyright 1998 by the American Geophysical Union.

  4. Block and shear-zone architecture of the Minnesota River Valley subprovince: Implications for late Archean accretionary tectonics

    USGS Publications Warehouse

    Southwick, D.L.; Chandler, V.W.

    1996-01-01

    The Minnesota River Valley subprovince of the Superior Province is an Archean gneiss terrane composed internally of four crustal blocks bounded by three zones of east-northeast-trending linear geophysical anomalies. Two of the block-bounding zones are verified regional-scale shears. The geological nature of the third boundary has not been established. Potential-field geophysical models portray the boundary zones as moderately north-dipping surfaces or thin slabs similar in strike and dip to the Morris fault segment of the Great Lakes tectonic zone at the north margin of the subprovince. The central two blocks of the subprovince (Morton and Montevideo) are predominantly high-grade quartzofeldspathic gneiss, some as old as 3.6 Ga, and late-tectonic granite. The northern and southern blocks (Benson and Jeffers, respectively) are judged to contain less gneiss than the central blocks and a larger diversity of syntectonic and late-tectonic plutons. A belt of moderately metamorphosed mafic and ultramafic rocks having some attributes of a dismembered ophiolite is partly within the boundary zone between the Morton and Montevideo blocks. This and the other block boundaries are interpreted as late Archean structures that were reactivated in the Early Proterozoic. The Minnesota River Valley subprovince is interpreted as a late accretionary addition to the Superior Province. Because it was continental crust, it was not subductible when it impinged on the convergent southern margin of the Superior Craton in late Archean time, and it may have accommodated to convergent-margin stresses by dividing into blocks and shear zones capable of independent movement.

  5. A Role of Low-angle Thrust Fault for the Occurrence of rain-induced Rockslides in an Accretionary Complex

    NASA Astrophysics Data System (ADS)

    Arai, N.; Chigira, M.

    2015-12-01

    Recently, extreme weather related to global warming occurs frequently all over the world; there have been many record-setting rainfall events. Accordingly, potential of rain-induced rockslides increases. Examples of recent rain-induced rock avalanches with tens or more than a hundred of fatalities are a rockslide in Shiaolin village, Taiwan by 2009 Typhoon Morakot, and rockslides induced by 2011 typhoon Talas in Japan. However, the method to predict potential sites of rockslides is not established. Geological causes of rockslides are site specific and they must be clarified for each case. 2011 Typhoon Talas induced more than 50 rockslides in the outer belt of the Southwest Japan, where is underlain by Cretaceous - lower Miocene accretionary complexes. We performed thorough geological mapping in the Akatani area, where two huge rockslides occurred with volumes of 2 million and 8 million m3 respectively. As a result, we found that these two rockslides had their sliding surfaces along a low-angle-thrust with a dip of 29°~40° extending more than 5 km, which fault we name Kawarabi-thrust. This thrust has a fracture zone of 6.0 m in the maximum width, composed of clayey fault breccia with a few layers of black gouges. These fault materials are very weak and impermeable, so the fracture zone is expected to prevent the groundwater filtration and build up the pore pressure. This thrust had been exposed along the riversides at the foot of the two rockslides, which suggests that the slopes on the thrust had been destabilized by the undercutting of long-term river incision. The destabilization induced gravitational slope deformation with small scarps before the catastrophic failure. Our finding suggests that locating a large-scale low-angle-thrust is essentially important to predict potential sites of catastrophic rockslides as well as interpreting the internal structure of gravitationally deformed slopes.

  6. Intrinsic versus extrinsic variability of analogue sand-box experiments - Insights from statistical analysis of repeated accretionary sand wedge experiments

    NASA Astrophysics Data System (ADS)

    Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

    2015-06-01

    Analogue models are not perfectly reproducible even under controlled boundary conditions which make their interpretation and application not always straight forward. As any scientific experiment they include some random component which can be influenced both by intrinsic (inherent processes) and extrinsic (boundary conditions, material properties) sources. In order to help in the assessment of analogue model results, we discriminate and quantify the intrinsic versus extrinsic variability of results from "sandbox" models of accretionary wedges that were repeated in a controlled environment. The extrinsic source of variability, i.e. the parameter varied is the nature of the décollement (material, friction and thickness). Experiment observables include geometric properties of the faults (lifetime, spacing, dip) as well as wedge geometry (height, slope, length). For each variable we calculated the coefficient of variance (CV) and quantified the variability as a symmetric distribution (Normal, Laplacian) or asymmetric distribution (Gamma) using a Chi squared test (χ2). Observables like fault dip/back thrust dip (CV = 0.6-0.7/0.2-0.6) are less variable and decrease in magnitude with decreasing basal friction. Variables that are time dependent like fault lifetime (CV = 0.19-0.56) and fault spacing (CV = 0.12 - 0.36) have a higher CV consequently affecting the variability of wedge slope (CV = 0.12-0.33). These observables also increase in magnitude with increasing basal friction. As the mechanical complexity of the evolving wedge increases over time so does the CV and asymmetry of the distribution. In addition, we confirm the repeatability of experiments using an ANOVA test. Through the statistical analysis of results from repeated experiments we present a tool to quantify variability and an alternative method to gaining better insights into the dynamic mechanics of deformation in analogue sand wedges.

  7. Fault-Propagation Fold vs. Fault-Bend Fold: Two Different Modes of Deformation in Accretionary Prisms

    NASA Astrophysics Data System (ADS)

    Ogawa, Y.

    2015-12-01

    Well exposed on land accretionary prisms of Neogene age in the Miura and Boso Peninsulas in central Japan offer excellent examples for consideration of the significance and implication of two different modes of layer-parallel shortening: fault-propagation folds and fault-bend folds. Some folds in the beds in the Misaki and Shiramazu Formations of middle Miocene to early Pliocene and early Pleistocene age respectively explain long distant layer-parallel slip made of many small scale (tens of cm order) duplex structures of antiformal stack or hinterland-dipping type, or both. The duplexed layer parts are unconformably overlain by liquefied or fluidized turbidite layers on top, suggesting very shallow burial depths during deformation or duplication as slide or slump deposits. Some blocks of hinterland-dipping type duplexes are involved in breccia beds that are formed by liquefaction or mud diapiric intrusion. In addition, in the Misaki Formations, large scale duplex structures of hinterland-dipping type with bi-divergent thrust system on orders of hundreds of meters are mapped in stratified layers. Those duplex systems of various scales are a type of fault-bend fold that is characterized by layer parallel slip within a single, specific bed, that then propagated upward to slip again within the other specific bed. Many of the examples of fault-bend folds formed at shallow burial depths, probably just after the deposition. Another type of layer parallel shortening in the Misaki and Shiramazu Formations is fault-propagation folds that are characterized by propagation of thrust faults by forming synclines and anticlines, resulting in an upward concave thrust system that splays out from the basal slip to develop. These two different types of folds are developed within layers in one side, and in another side cutting through the layers, and could be applied to the submarine Nankai prism of the same ages.

  8. In situ stress magnitudes at the toe of the Nankai Trough Accretionary Prism, offshore Shikoku Island, Japan

    NASA Astrophysics Data System (ADS)

    Huffman, K. A.; Saffer, D. M.

    2016-02-01

    Quantifying the orientation and magnitude of tectonic stresses is essential toward understanding deformation and faulting in subduction zones. However, constraints on in situ horizontal stress magnitudes (Shmin and SHmax) are rare. We estimate Shmin and SHmax at Ocean Drilling Program Site 808 at the toe of the Nankai accretionary prism offshore Japan, using coupled constraints from (1) the width of wellbore breakouts together with estimates of rock strength and a model describing stress redistribution at the borehole wall and (2) limits on regional differential stress defined by failure on preexisting faults. Our analysis extends from 175 to 915 m below seafloor (mbsf) and spans the active frontal thrust. For an upper bound on rock unconfined compressive strength (UCS) and assuming hydrostatic formation pore pressure, Shmin and SHmax (referenced to the seafloor) increase from 6.5 MPa at 175 mbsf to 17.4 MPa at 915 mbsf, with the stress state gradually transitioning from a thrust or strike-slip faulting regime above 800 mbsf to a normal faulting regime below. For cases with higher formation pore pressure, horizontal stresses are slightly lower but follow a similar pattern. We show that estimated Shmin and SHmax are strongly dependent on UCS, breakout width, and friction coefficient, all of which are characterized by uncertainty. Our results suggest that the prism is near thrust failure in the upper ~300 mbsf, but far from failure below. This may be reconciled with active thrusting if thrust faults are locally weaker than the surrounding rock or if SHmax fluctuates during the seismic cycle.

  9. Distinct deformational history of two contrasting tectonic domains in the Chinese Altai: Their significance in understanding accretionary orogenic process

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Sun, Min; Schulmann, Karel; Zhao, Guochun; Wu, Qihang; Jiang, Yingde; Guy, Alexandra; Wang, Yuejun

    2015-04-01

    The Chinese Altai, a key component of the western Central Asian Orogenic Belt, is considered to be formed through multiple accretions of different terranes. However, the deformational histories of each terrane (tectonic domain), i.e. structural records before and after the accretion, are rarely studied, which has hindered our understanding of the accretionary processes. To fill the gap, a systematic macro- and microscopic structural analysis was carried out on two contrasting litho-tectonic units, i.e. the early Paleozoic low-grade Alegedayi Ophiolitic Complex (AOC) juxtaposed to the high grade Tarlang Granitic Massif (TGM). Selected rock samples were analyzed using zircon U-Pb isotopic dating to constrain the timing of polyphase deformation. Our structural and geochronological data suggest that the two litho-tectonic units were initially detached and located in different crustal levels and experienced distinct phases of deformation under contrasting P-T conditions. They were mutually accreted with each other in the early Devonian and jointly underwent a WNW-ESE-directed shortening deformational event (D1) at ∼390 Ma. The change of tectonic regime was further enhanced by a subsequent NNE-SSW-directed shortening deformation (D2) after ∼ 380 Ma. The shortening process ended before the crustal-scale sinistral strike-slip shearing deformation along the Erqis fault zone at 290 - 240 Ma. Results of this study provide solid field-based evidence for a model that the Chinese Altai initially underwent a nearly E-W-oriented subduction-accretional event in the middle Paleozoic, before it was reoriented to a nearly N-S-oriented convergence.

  10. A review of volcanic ash aggregation

    NASA Astrophysics Data System (ADS)

    Brown, R. J.; Bonadonna, C.; Durant, A. J.

    2012-01-01

    Most volcanic ash particles with diameters <63 μm settle from eruption clouds as particle aggregates that cumulatively have larger sizes, lower densities, and higher terminal fall velocities than individual constituent particles. Particle aggregation reduces the atmospheric residence time of fine ash, which results in a proportional increase in fine ash fallout within 10-100 s km from the volcano and a reduction in airborne fine ash mass concentrations 1000 s km from the volcano. Aggregate characteristics vary with distance from the volcano: proximal aggregates are typically larger (up to cm size) with concentric structures, while distal aggregates are typically smaller (sub-millimetre size). Particles comprising ash aggregates are bound through hydro-bonds (liquid and ice water) and electrostatic forces, and the rate of particle aggregation correlates with cloud liquid water availability. Eruption source parameters (including initial particle size distribution, erupted mass, eruption column height, cloud water content and temperature) and the eruption plume temperature lapse rate, coupled with the environmental parameters, determines the type and spatiotemporal distribution of aggregates. Field studies, lab experiments and modelling investigations have already provided important insights on the process of particle aggregation. However, new integrated observations that combine remote sensing studies of ash clouds with field measurement and sampling, and lab experiments are required to fill current gaps in knowledge surrounding the theory of ash aggregate formation.

  11. Erodibility of fly ash-treated minesoils

    SciTech Connect

    Gorman, J.M.; Sencindiver, J.C.; Singh, R.N.

    1997-12-31

    Fly ash, a by-product of coal-fired power plants, has been used successfully in reclaiming adverse mine sites such as abandoned mine lands by improving minesoil chemical and physical properties. But, the fine sand-silt particle size of fly ash may make it more susceptible to detachment and transport by erosive processes. Furthermore, the high content of silt-size particles in fly ash may make it more susceptable to surface crust formation resulting in reduced infiltration and increased surface runoff and erosion. In the summer of 1989, fly ash/wood waste mixtures were surface applied on two separate mine sites, one with 10% slope and the other 20% slope, in central Preston County, West Virginia. Erosion rates were measured directly using the Linear Erosion/Elevation Measuring Instrument (LEMI). Erosion measurements were taken during the first two growing seasons on both sites. Erosion values were up to five times greater on the fly ash-treated minesoil than on the minesoil without fly ash cover. Mulching with wood chips reduced fly ash erosion to about one-half the loss of the unmulched plots. Erosion was related to both the amount and type of ground cover. Increased vegetative ground cover resulted in reduced erosion. Mosses and fungi appeared to provide better erosion protection than grass-legume cover.

  12. Municipal solid-waste incinerator fly ash

    SciTech Connect

    Goh, A.T.C. ); Joohwa Tay )

    1993-05-01

    Many highly urbanized cities are faced with the problem of disposal of municipal solid waste because of the scarcity of land available for landfilling. One possible solution is the incineration of the municipal solid waste. After incineration, about 20% by weight of fly ash and other residues are produced. Investigations into the physical and engineering properties of the fly ash derived from municipal solid-waste incineration indicate that the material is a potential source of fill material, with low compacted density and high strength. The fly ash was relatively free draining, with permeability of the same order of magnitude as coarse grained materials. The use of the fly ash as an admixture in the stabilization of a soft marine clay showed improved undrained shear strengths and lower compressive properties. Leachate tests on the samples of fly ash initially indicated trace quantities of cadmium and chromium in excess of the acceptable drinking-water limits. After leaching for 28 days, the concentrations fell below the drinking-water limits. Lime and cement can be used to stabilize the fly ash. The concentrations of heavy metals in the leachates of lime and cement treated fly ash were nondetectable.

  13. Ash iron mobilization in volcanic eruption plumes

    NASA Astrophysics Data System (ADS)

    Hoshyaripour, G.; Hort, M.; Langmann, B.

    2014-12-01

    It has been shown that volcanic ash fertilizes the Fe-limited areas of the surface ocean through releasing soluble iron. As ash iron is mostly insoluble upon the eruption, it is hypothesized that heterogeneous in-plume and in-cloud processing of the ash promote the iron solubilization. Direct evidences concerning such processes are, however, lacking. In this study, a 1-D numerical model is developed to simulate the physicochemical interactions of gas-ash-aerosol in volcanic eruption plumes focusing on the iron mobilization processes at temperatures between 600 and 0 °C. Results show that sulfuric acid and water vapor condense at ~150 and ~50 °C on the ash surface, respectively. This liquid phase then efficiently scavenges the surrounding gases (>95% of HCl, 3-20% of SO2 and 12-62% of HF) forming an extremely acidic coating at the ash surface. The low pH conditions of the aqueous film promote acid-mediated dissolution of the Fe-bearing phases present in the ash material. We estimate that 0.1 to 33% of the total iron available at the ash surface is dissolved in the aqueous phase before the freezing point is reached. The efficiency of dissolution is controlled by the halogen content of the erupted gas as well as the mineralogy of the iron at ash surface: elevated halogen concentrations and presence of Fe2+-carrying phases lead to the highest dissolution efficiency. Findings of this study are in agreement with the data obtained through leaching experiments.

  14. Marine mesocosm bacterial colonisation of volcanic ash

    NASA Astrophysics Data System (ADS)

    Witt, Verena; Cimarelli, Corrado; Ayris, Paul; Kueppers, Ulrich; Erpenbeck, Dirk; Dingwell, Donald; Woerheide, Gert

    2015-04-01

    Volcanic eruptions regularly eject large quantities of ash particles into the atmosphere, which can be deposited via fallout into oceanic environments. Such fallout has the potential to alter pH, light and nutrient availability at local scales. Shallow-water coral reef ecosystems - "rainforests of the sea" - are highly sensitive to disturbances, such as ocean acidification, sedimentation and eutrophication. Therefore, wind-delivered volcanic ash may lead to burial and mortality of such reefs. Coral reef ecosystem resilience may depend on pioneer bacterial colonisation of the ash layer, supporting subsequent establishment of the micro- and ultimately the macro-community. However, which bacteria are involved in pioneer colonisation remain unknown. We hypothesize that physico-chemical properties (i.e., morphology, mineralogy) of the ash may dictate bacterial colonisation. The effect of substrate properties on bacterial colonisation was tested by exposing five substrates: i) quartz sand ii) crystalline ash (Sakurajima, Japan) iii) volcanic glass iv) carbonate reef sand and v) calcite sand of similar grain size, in controlled marine coral reef aquaria under low light conditions for six months. Bacterial communities were screened every month by Automated Ribosomal Intergenic Spacer Analysis of the 16S-23S rRNA Internal Transcribed Spacer region. Multivariate statistics revealed discrete groupings of bacterial communities on substrates of volcanic origin (ash and glass) and reef origin (three sands). Analysis of Similarity supported significantly different communities associated with all substrates (p=0.0001), only quartz did not differ from both carbonate and calcite sands. The ash substrate exhibited the most diverse bacterial community with the most substrate-specific bacterial operational taxonomic units. Our findings suggest that bacterial diversity and community composition during colonisation of volcanic ash in a coral reef-like environment is controlled by the

  15. Change in stress with seismic cycles identified at an out of sequence thrust in an on-land accretionary complex: The Nobeoka thrust, Shimanto Belt, Kyusyu, SW Japan

    NASA Astrophysics Data System (ADS)

    Yamaguchi, M.; Hashimoto, Y.; Yamaguchi, A.; Kimura, G.

    2011-12-01

    Seismic surveys along accretionary prisms have revealed that the out-of sequence thrusts (OSTs) are commonly developed within accretionary wedges branching from seismogenic subduction plate boundaries. The OSTs are also recognized in on-land accretionary complexes as large thrust faults cutting paleo-thermal structures. The OSTs are thought to play a role in tsunami genesis at a coseismic event. Stress history on OSTs is significant to understand the OSTs' role in seismic cycles. We estimated, thus palaeostresses from micro-faults along an OST in an on-land accretionary complexes. We focused on the Nobeoka fault which is an OST in an on-land accretionary complex, the Shimato Belt, Kyusyu, SW Japan. A gap in paleothermal temperature (up to 70 degree C) is observed at the fault. The Nobeoka thrust strikes almost EW at coastline. The Cretaceous Makimine formation and Paleogene Kitagawa formation are located at the hanging wall of the fault, comprising mainly of pelitic schist. The footwall of the fault is the Paleogene Hyuga formation composed mainly of shale. A lot of micro-faults are well developed just below the thrust for a few hundred meters to the south. Those micro faults are considered to be related to the Nobeoka thurst because slip direction and sense of the micro-faults are consistent with that of the Nobeoka thrust. The micro-faults are commonly accompanied by mineral veins of quartz and ankerite. Yamaguchi et al. (2010) suggested that the differences of mineral veins are possibly related to the seismic cycle. In this study, we conducted stress inversion analysis for the micro-faults to examine the change in stress between them, which might be related to the seismic cycle. We divided the micro-fault into two as a micro-fault with quartz veins and that with ankerite veins. Slip direction from slicken fibers and slip sense by slicken steps were obtained. HIM (hough inversion method) by Yamaji et al. (2006) was used to estimate the stress. Two stress states

  16. Characterizing the Hydrological Properties of Wildfire Ash

    NASA Astrophysics Data System (ADS)

    Woods, S.; Balfour, V.

    2010-12-01

    Wildfires are extreme disturbance events that can increase runoff and erosion rates by 2-3 orders of magnitude. Fire related sediment presents a significant geomorphic hazard in terms of debris flows and other catastrophic erosion events, but ultimately plays a key role in landscape evolution in fire prone regions. The hyper-dessicated ash and soil layers making up the near surface profile in recently burned areas respond very differently to rainfall than the litter and unburned soil that existed prior to the fire. Limited knowledge regarding the hydrological properties of the ash-soil profile, and the ash layer in particular, currently limits efforts to model the infiltration process in burned areas and hence predict the location and magnitude of post fire runoff and erosion events. In our ongoing research we are investigating and quantifying the hydrologic properties of wildfire ash. Wherever possible we use conventional laboratory techniques from soil hydrology but in some cases we have had to adapt these techniques to account for the distinct physical and chemical properties of ash, such as the variability in particle density and the partial solubility of many of the mineral components. Some of the hydrologic properties of ash, such as the hydraulic conductivity, are similar to those of a mineral soil with a comparable particle size distribution. For example, ash from Spain with a silty loam texture had a hydraulic conductivity of 7 x 10-4 cm s-1, which is within the range reported for mineral soils with the same texture. However, other properties such as the porosity are considerably different; an undisturbed ash sample with a sandy loam texture had a porosity of 93 percent compared to the typical range of 30 to 50 percent for mineral soils with this texture. Scanning electron microscopy analysis indicates that the contrasting hydrologic properties of ash and soil are due to differences in the particle shape, particle packing and pore structure. Using examples

  17. Rocky Flats ash test procedure (sludge stabilization)

    SciTech Connect

    Winstead, M.L.

    1995-09-14

    Rocky Flats Ash items have been identified as the next set of materials to be stabilized. This test is being run to determine charge sizes and soak times to completely stabilize the Rocky Flats Ash items. The information gathered will be used to generate the heating rampup cycle for stabilization. This test will also gain information on the effects of the glovebox atmosphere (moisture) on the stabilized material. This document provides instructions for testing Rocky Flats Ash in the HC-21C muffle furnace process.

  18. Volcanic Ash Transport and Dispersion Forecasting

    NASA Astrophysics Data System (ADS)

    Servranckx, R.; Stunder, B.

    2006-12-01

    Volcanic ash transport and dispersion models (VATDM) have been used operationally since the mid 1990's by the International Civil Aviation Organization (ICAO) designated Volcanic Ash Advisory Centers (VAAC) to provide ash forecast guidance. Over the years, significant improvements in the detection and prediction of airborne volcanic ash have been realized thanks to improved models, increases in computing power, 24-hr real time monitoring by VAACs / Meteorological Watch Offices and close coordination with Volcano Observatories around the world. Yet, predicting accurately the spatial and temporal structures of airborne volcanic ash and the deposition at the earth's surface remains a difficult and challenging problem. The forecasting problem is influenced by 3 main components. The first one (ERUPTION SOURCE PARAMETERS) comprises all non-meteorological parameters that characterize a specific eruption or volcanic ash cloud. For example, the volume / mass of ash released in the atmosphere, the duration of the eruption, the altitude and distribution of the ash cloud, the particle size distribution, etc. The second component (METEOROLOGY) includes all meteorological parameters (wind, moisture, stability, etc.) that are calculated by Numerical Weather Prediction models and that serve as input to the VATDM. The third component (TRANSPORT AND DISPERSION) combines input from the other 2 components through the use of VATDM to transport and disperse airborne volcanic ash in the atmosphere as well as depositing it at the surface though various removal mechanisms. Any weakness in one of the components may adversely affect the accuracy of the forecast. In a real-time, operational response context such as exists at the VAACs, the rapid delivery of the modeling results puts some constraints on model resolution and computing time. Efforts are ongoing to evaluate the reliability of VATDM forecasts though the use of various methods, including ensemble techniques. Remote sensing data

  19. A process for resolving ash issues

    SciTech Connect

    Barnes, J.M.

    1995-09-01

    Waste-to-energy (WTE) plants leave about 10 percent of the combusted trash volume as ash. The residue has been a problem for may WTE plant operators and the communities they serve. Recent changes in regulations governing ash handling have lead to new sampling procedures, more frequent testing, and more costly handling and treatment processes. The Nashville Thermal Transfer Corporation`s WTE plant is involved in an project developed by the American Ash Recycling Corp, which addresses environmental concerns, recycling, and cost concerns. This article describes the project and how it tackles these three issues. 4 refs., 1 fig.

  20. Electrodialytic removal of Cd from biomass combustion fly ash suspensions.

    PubMed

    Kirkelund, Gunvor M; Damoe, Anne J; Ottosen, Lisbeth M

    2013-04-15

    Due to relatively high concentrations of Cd, biomass combustion fly ashes often fail to meet Danish legislative requirements for recycling as fertilizer. In this study, the potential of using electrodialytic remediation for removal of Cd from four different biomass combustion fly ashes was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laboratory scale electrodialytic remediation experiments were conducted with each ash. The initial Cd concentration in the ashes varied between 8.8 mg Cd/kg (co-firing ash) and 64 mg Cd/kg (pre-washed straw ash), and pH varied from 3.7 (co-firing ash) to 13.3 (wood ash). In spite of such large variations between the ashes, the electrodialytic method showed to be sufficiently robust to treat the ashes so the final Cd concentration was below 2.0mg Cd/kg DM in at least one experiment done with each ash. This was obtained within 2 weeks of remediation and at liquid to solid (L/S) ratios of L/S 16 for the pre-washed straw ash and L/S 8 for the straw, co-firing and wood ash. PMID:23454460

  1. Seaward- Versus Landward-Verging Thrusts in Accretionary Wedges: A Numerical Modeling Study of the Effects of Heterogeneity in Pore Fluid Pressure and Frictional Strength

    NASA Astrophysics Data System (ADS)

    Ito, G.; Moore, G. F.; Olive, J. A. L.; Weiss, J. R.

    2015-12-01

    Whereas seaward-verging thrust faults are, by far, the most common large faults associated with accretionary wedges, the importance of the globally rare, landward verging thrusts has recently been highlighted given the prominence of landward vergence along the Cascadia margin as well as along the Andaman-Sumatra subduction zone, especially in the rupture area of the great 2004 earthquake. The mechanical processes that lead to seaward- versus landward-verging thrusts in accretionary wedges has long been a topic of debate. A weak frictional décollement is one explanation that indeed promotes landward vergence, but not only so, because the typical pattern is of dual verging conjugate faults. A non-brittle, ductile décollement is a second explanation that has been shown in the laboratory to produce a wide sequence of only landward-verging thrusts, but the mechanical causes are not well understood and numerical modeling studies have yet to reproduce this behavior. A seaward-dipping backstop is a third explanation; it promotes landward vergence locally, but more distally the backstop effects diminish and the sense of vergence transitions back to seaward. Mohr-Coulomb and minimum work theory predict that landward vergence should predominate when the direction of maximum principal compression dips landward. We hypothesize that such a condition can arise due to the migration of pore fluids and the associated spatial heterogeneity in frictional strength within the wedge. We test this hypothesis using 2-D numerical models that use a finite-difference, particle-in-cell method for simulating the deformation of an accretionary wedge with a viscoelastic-plastic rheology. With a uniform internal frictional strength, the calculations reproduce many of the faulting behaviors seen in prior laboratory and numerical modeling studies. We are exploring the impacts of heterogeneity in pore fluid pressure and frictional strength on the pattern and vergence of thrust faults.

  2. Origin and transport of pore fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of pore water at cold seep sites off Kumano

    NASA Astrophysics Data System (ADS)

    Toki, Tomohiro; Higa, Ryosaku; Ijiri, Akira; Tsunogai, Urumu; Ashi, Juichiro

    2014-12-01

    We used push corers during manned submersible dives to obtain sediment samples of up to 30 cm from the subseafloor at the Oomine Ridge. The concentrations of B in pore water extracted from the sediment samples from cold seep sites were higher than could be explained by organic matter decomposition, suggesting that the seepage fluid at the site was influenced by B derived from smectite-illite alteration, which occurs between 50°C and 160°C. Although the negative δ18OH2O and δDH2O values of the pore fluids cannot be explained by freshwater derived from clay mineral dehydration (CMD), we considered the contribution of pore fluids in the shallow sediments of the accretionary prism, which showed negative δ18OH2O and δDH2O values according to the results obtained during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316. We calculated the mixing ratios based on a four-end-member mixing model including freshwater derived from CMD, pore fluids in the shallow (SPF) accretionary prism sediment, seawater (SW), and freshwater derived from methane hydrate (MH) dissociation. However, the Oomine seep fluids were unable to be explained without four end members, suggesting that deep-sourced fluids in the accretionary prism influenced the seeping fluids from this area. This finding presents the first evidence of deep-sourced fluids at cold seep sites in the Oomine Ridge, indicating that a megasplay fault is a potential pathway for the deep-sourced fluids.

  3. Triassic deformation of Permian Early Triassic arc-related sediments in the Beishan (NW China): Last pulse of the accretionary orogenesis in the southernmost Altaids

    NASA Astrophysics Data System (ADS)

    Tian, Zhonghua; Xiao, Wenjiao; Sun, Jimin; Windley, Brian F.; Glen, Richard; Han, Chunming; Zhang, Zhiyong; Zhang, Ji'en; Wan, Bo; Ao, Songjian; Song, Dongfang

    2015-11-01

    The Beishan orogenic collage (BOC) in the southernmost Altaids provides evidence of the final stage of evolution of the Paleo-Asian Ocean. However, the closure time of the Paleo-Asian Ocean in the BOC is controversial. From field mapping, and structural analysis of mesoscale, superposed folds in Early Triassic sediments in the Hongyanjing Basin in the central BOC, we define at least two phases of deformation, which we can bracket in age as end-Permian to Early-Late Triassic. The sandstones in the basin are poorly sorted with angular clasts, which indicates immaturity characteristic of proximal and rapid deposition. Geochemical data indicate that the Hongyanjing Basin probably developed in an arc-related setting near an active continental margin or mature island arc. Combined with published regional geological data, we interpret the Hongyanjing Basin as a Permian-Early Triassic inter-arc basin between the Carboniferous Mazongshan arc to the north and the Ordovician to Permian Huaniushan-Dundunshan arc to the south. In addition, the age distribution of our sediments shows that the active continental margin or continental arc on which the Hongyanjing arc-related basin sat was somehow independently distributed in the Paleo-Asian Ocean without any major contribution of provenance from the Tarim Craton and Dunhuang Block to the south and Southern Mongolia accretionary system to the north. Deformation of the superposed folds began in the end-Permian, continued in the Early Triassic, and ended before the middle Late Triassic (219 Ma). Therefore the accretionary orogenesis in the Beishan part of the southernmost Altaids was still ongoing in the early to middle Triassic, and it finished in the Late Triassic, which might have been the last pulse of the accretionary orogenesis in the southernmost Altaids. We correlate this terminal event with tectonic developments in the Kunlun and Qinling orogens in the Tethyan domain.

  4. Fly Ash Disposal in Ash Ponds: A Threat to Ground Water Contamination

    NASA Astrophysics Data System (ADS)

    Singh, R. K.; Gupta, N. C.; Guha, B. K.

    2016-09-01

    Ground water contamination due to deposition of fly ash in ash ponds was assessed by simulating the disposal site conditions using batch leaching test with fly ash samples from three thermal power plants. The periodic analysis of leachates was performed for selected elements, Fe, Cu, Ni, Cr, Pb and Cd in three different extraction solutions to determine the maximum amount that can be leached from fly ash. It was observed that at low pH value, maximum metals are released from the surface of the ash into leachate. The average concentration of these elements found in ground water samples from the nearby area of ash ponds shows that almost all the metals except `Cr' are crossing the prescribed limits of drinking water. The concentration of these elements at this level can endanger public health and environment.

  5. Fly Ash Disposal in Ash Ponds: A Threat to Ground Water Contamination

    NASA Astrophysics Data System (ADS)

    Singh, R. K.; Gupta, N. C.; Guha, B. K.

    2016-07-01

    Ground water contamination due to deposition of fly ash in ash ponds was assessed by simulating the disposal site conditions using batch leaching test with fly ash samples from three thermal power plants. The periodic analysis of leachates was performed for selected elements, Fe, Cu, Ni, Cr, Pb and Cd in three different extraction solutions to determine the maximum amount that can be leached from fly ash. It was observed that at low pH value, maximum metals are released from the surface of the ash into leachate. The average concentration of these elements found in ground water samples from the nearby area of ash ponds shows that almost all the metals except `Cr' are crossing the prescribed limits of drinking water. The concentration of these elements at this level can endanger public health and environment.

  6. Temporal variation of the Rayleigh admittance: Implication for S-wave velocity changes in the toe of the Nankai accretionary prism

    NASA Astrophysics Data System (ADS)

    Tonegawa, Takashi; Araki, Eiichiro; Kimura, Toshinori; Nakamura, Takeshi

    2016-04-01

    A cabled seafloor network with 20 stations (DONET: Dense Oceanfloor Network System for Earthquake and Tsunamis) has been constructed on the accretionary prism at the Nankai subduction zone of Japan between March 2010 and August 2011, which means that the observation period became more than 4 years. Each station contains broadband seismometers and absolute and differential pressure gauges. In this study, we estimated the Rayleigh admittance at the seafloor for each station, i.e., an amplitude transfer function from pressure to displacement in the frequency band of microseisms, particularly for the fundamental Rayleigh mode of 0.1-0.2 Hz. The pattern of the transfer function depends on the S-wave velocity structure at shallow depths beneath stations (Ruan et al., 2014, JGR). Therefore, plotting the Rayleigh admittance as functions of time and frequency, we investigated temporal variations of S-wave velocity within the accretionary prism. We calculated the displacement seismogram by removing the instrument response from the velocity seismogram for each station. The pressure record observed at the differential pressure gauge was used in this study because of a high resolution of the pressure observation. In the frequency domain, we smoothed the two kinds of spectra (displacement and pressure) with ±2 neighboring samples, and estimated the amplitude transfer function of displacement/pressure. Here, we used the ambient noise of the two records. To display their temporal variations, we plot the averaged transfer function with intervals of 7 days. As a result, we found a long-term temporal variation of the Rayleigh admittance at two stations. These stations are located at the southern part of the array and near the trench, where the activities of very-low frequency earthquakes (VLFEs) within the accretionary prism on 2004, 2009, and 2011 have been previously reported. The admittance at a frequency of 0.1 Hz has gradually decreased during the observation period, which

  7. Enhancement in mechanical properties of concrete due to blended ash

    SciTech Connect

    Naik, T.R.; Singh, S.S.; Hossain, M.M.

    1996-01-01

    This study was carried out to evaluate the effects of blended ash mixture on mechanical properties of concrete. In this study two reference mixtures were used. One of the mixtures was a no-fly ash mixture, and the other mixture contained 35% unblended Class C fly ash. Additional mixtures were composed of three blends of Class C and Class F fly ash while maintaining a total fly ash content of 40% of the total cementitious materials. Mechanical properties such as compressive strength, tensile strength, flexural strength, and modulus of elasticity were determined as a function of age ranging from 1 to 91 days. The results showed that blending of Class F fly ash with Class C fly ash showed either comparable or better results compared to either the reference mixture without fly ash or the unblended Class C fly ash concrete mixture at a fly ash concentration of 40% of total cementitious materials.

  8. Effect of ash circulation in gasification melting system on concentration and leachability of lead in melting furnace fly ash.

    PubMed

    Okada, Takashi; Suzuki, Masaru

    2013-11-30

    In some gasification-melting plants, generated melting furnace fly ash is returned back to the melting furnace for converting the ash to slag. This study investigated the effect of such ash circulation in the gasification-melting system on the concentration and leachability of lead in the melting furnace fly ash. The ash circulation in the melting process was simulated by a thermodynamic calculation, and an elemental analysis and leaching tests were performed on a melting furnace fly ash sample collected from the gasification-melting plant with the ash circulation. It was found that by the ash circulation in the gasification-melting, lead was highly concentrated in the melting furnace fly ash to the level equal to the fly ash from the ash-melting process. The thermodynamic calculation predicted that the lead volatilization by the chlorination is promoted by the ash circulation resulting in the high lead concentration. In addition, the lead extraction from the melting furnace fly ash into a NaOH solution was also enhanced by the ash circulation, and over 90% of lead in the fly ash was extracted in 5 min when using 0.5 mol l(-1) NaOH solution with L/S ratio of 10 at 100 °C. Based on the results, a combination of the gasification-melting with the ash circulation and the NaOH leaching method is proposed for the high efficient lead recovery.

  9. Biotoxicity evaluation of fly ash and bottom ash from different municipal solid waste incinerators.

    PubMed

    Chou, Jing-Dong; Wey, Ming-Yen; Liang, Hsiu-Hao; Chang, Shih-Hsien

    2009-08-30

    Different types of municipal solid waste incinerator (MSWI) fly and bottom ash were extracted by TCLP and PBET procedures. The biotoxicity of the leachate of fly ash and bottom ash was evaluated by Vibrio fischeri light inhibition test. The results indicate the following: (1) The optimal solid/liquid ratio was 1:100 for PBET extraction because it had the highest Pb and Cu extractable mass from MSWI fly ash. (2) The extractable metal mass from both fly ash and bottom ash by PBET procedure was significantly higher than that by TCLP procedure. (3) The metal concentrations of fly ash leachate from a fluidized bed incinerator was lower than that from mass-burning and mass-burning combined with rotary kiln incinerator. (4) The TCLP and PBET leachate from all MSWI fly ash samples showed biotoxicity. Even though bottom ash is regarded as a non-hazardous material, its TCLP and PBET leachate also showed biotoxicity. The pH significantly influenced the biotoxicity of leachate. PMID:19264394

  10. Biotic and abiotic factors affect green ash volatile production and emerald ash borer adult feeding preference.

    PubMed

    Chen, Yigen; Poland, Therese M

    2009-12-01

    The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an exotic woodborer first detected in 2002 in Michigan and Ontario and is threatening the ash resource in North America. We examined the effects of light exposure and girdling on green ash (Fraxinus pennsylvanica Marsh) volatile production, and effects of light exposure, girdling, and leaf age on emerald ash borer adult feeding preferences and phototaxis. Green ash seedlings grown under higher light exposure had lower amounts of three individual volatile compounds, (Z)-3-hexenol, (E)-beta-ocimene, and (Z,E)-alpha-farnesene, as well as the total amount of six detected volatile compounds. Girdling did not affect the levels of these volatiles. Emerald ash borer females preferred mature leaves, leaves from girdled trees, and leaves grown in the sun over young leaves, leaves from nongirdled trees, and leaves grown in the shade, respectively. These emerald ash borer preferences were most likely because of physical, nutritional, or biochemical changes in leaves in response to the different treatments. Emerald ash borer females and males showed positive phototaxis in laboratory arenas, a response consistent with emerald ash borer preference for host trees growing in sunlight.

  11. Potential products from North Dakota lignite fly ash. Final report

    SciTech Connect

    Anderson, G R

    1980-06-01

    Four major areas where fly ash can be used are explored. Concrete building blocks with fly ash replacing 50% of the portland cement have proven to be successful using current ASTM standards. Results in the ceramics area show that a ceramic-like product using fly ash and crushed glass with a small amount of clay as a green binder. Some preliminary results using sulfur ash in building materials are reported and with results of making wallboard from ash. (MHR)

  12. Fluidized bed gasification ash reduction and removal system

    DOEpatents

    Schenone, Carl E.; Rosinski, Joseph

    1984-02-28

    In a fluidized bed gasification system an ash removal system to reduce the particulate ash to a maximum size or smaller, allow the ash to cool to a temperature lower than the gasifier and remove the ash from the gasifier system. The system consists of a crusher, a container containing level probes and a means for controlling the rotational speed of the crusher based on the level of ash within the container.

  13. Fluidized bed gasification ash reduction and removal process

    DOEpatents

    Schenone, Carl E.; Rosinski, Joseph

    1984-12-04

    In a fluidized bed gasification system an ash removal system to reduce the particulate ash to a maximum size or smaller, allow the ash to cool to a temperature lower than the gasifier and remove the ash from the gasifier system. The system consists of a crusher, a container containing level probes and a means for controlling the rotational speed of the crusher based on the level of ash within the container.

  14. Clay Improvement with Burned Olive Waste Ash

    PubMed Central

    Mutman, Utkan

    2013-01-01

    Olive oil is concentrated in the Mediterranean basin countries. Since the olive oil industries are incriminated for a high quantity of pollution, it has become imperative to solve this problem by developing optimized systems for the treatment of olive oil wastes. This study proposes a solution to the problem. Burned olive waste ash is evaluated for using it as clay stabilizer. In a laboratory, bentonite clay is used to improve olive waste ash. Before the laboratory, the olive waste is burned at 550°C in the high temperature oven. The burned olive waste ash was added to bentonite clay with increasing 1% by weight from 1% to 10%. The study consisted of the following tests on samples treated with burned olive waste ash: Atterberg Limits, Standard Proctor Density, and Unconfined Compressive Strength Tests. The test results show promise for this material to be used as stabilizer and to solve many of the problems associated with its accumulation. PMID:23766671

  15. Rocky Flats Ash test procedure (sludge stabilization)

    SciTech Connect

    Funston, G.A.

    1995-06-14

    Rocky Flats Ash items have been identified as the next set of materials to be stabilized. This test is being run to determine charge sizes and soak times to completely stabilize the Rocky Flats Ash items. The information gathered will be used to generate the heating rampup cycle for stabilization. The test will provide information to determine charge sizes, soak times and mesh screen sizes (if available at time of test) for stabilization of Rocky Flats Ash items to be processed in the HC-21C Muffle Furnace Process. Once the charge size and soak times have been established, a program for the temperature controller of the HC-21C Muffle Furnace process will be generated for processing Rocky Flats Ash.

  16. Fly ash system technology improves opacity

    SciTech Connect

    2007-06-15

    Unit 3 of the Dave Johnston Power Plant east of Glenrock, WY, USA had problems staying at or below the opacity limits set by the state. The unit makes use of a Lodge Cottrell precipitator. When the plant changed to burning Power River Basin coal, ash buildup became a significant issue as the fly ash control system was unable to properly evacuate hoppers on the unit. To overcome the problem, the PLC on the unit was replaced with a software optimization package called SmartAsh for the precipitator fly ash control system, at a cost of $500,000. After the upgrade, there have been no plugged hoppers and the opacity has been reduced from around 20% to 3-5%. 2 figs.

  17. Valuable products from utility fly ash

    SciTech Connect

    DeBarr, J.A.; Rapp, D.M.

    1996-10-01

    Utilization of wastes from coal combustion is becoming an issue of increasing concern to coal companies and to the utilities that burn coal. The willingness of a coal company to dispose of the waste generated when its coal is burned is an advantage in a very competitive marketplace. Recovery of relatively valuable products from utility fly ash would help offset disposal costs, and may represent a component of an overall scheme of fly ash processing where fly ash is regarded as a potential resource rather than a waste. In this study, the quantity and quality of recoverable adsorbent carbon, magnetite and cenospheres is being evaluated. Preliminary results have demonstrated that quality adsorbent carbon and magnetite products can be prepared from fly ash derived from combustion of Illinois coals.

  18. Wildland fire ash: future research directions

    NASA Astrophysics Data System (ADS)

    Bodí, Merche B.; Martins, Deborah A.; Cerdà, Artemi; Balfour, Victoria N.; Santin, Cristina; Doerr, Stefan H.; Pereira, Paulo; Mataix-Solera, Jorge

    2014-05-01

    Ash is a key component of the forest fires affected land (Cerdà, 1998; Bodí et al., 2011; Pereira et al., 2013a). Ash controls the hydrological processes and determines the water repellency (Dlapa et al., 2012) and the infiltration rates (Cerdà and Doerr, 2008;). Moreover, ash is the key factor on runoff initiation and then on the soil erosion. Little is known about the impact of ash in different ecosystems, but during the last decade a substantial increase in the papers that show the role of ash in the Earth and Soil System were published (Bodí et al., 2012; Pereira et al., 2013b).. Ash is being found as the key component of the post-fire pedological, geomorphological and hydrological response after forest fires (Fernández et al., 2012; Martín et al., 2012; Bodí et al., 2013; Guénon et al., 2013; Pereira et al., 2013c). A recent State-of-the-Art review about wildland fire ash (Bodí et al., 2014) compiles the knowledge regarding the production, composition and eco-hydro-geomorphic effects of wildland fire ash. In the present paper we indicate the knowledge gaps detected and suggest topics that need more research effort concerning: i) data collection and analysis techniques: a) To develop standardized sampling techniques that allow cross comparison among sites and avoid inclusion of the underlying soil unless the burned surface soil forms part of the ash layer, b) To develop standardized methods to define and characterize ash, including its color, physical properties such as particle size distribution or density, proportion of pyrogenic C, chemical and biological reactivity and persistence in the environment, c) To validate, calibrate and test measurements collected through remote sensing with on-the-ground measurements. ii) ash production, deposition redistribution and fate: d) To untangle the significance of the effects of maximum temperature reached during combustion versus the duration of heating, e) To understand the production of ash by measuring its

  19. Electrification of Ash in Icelandic Volcanic Plumes

    NASA Astrophysics Data System (ADS)

    Nicoll, K.; Aplin, K. L.; Houghton, I.

    2014-12-01

    Volcanic ash is known to charge electrically, producing some of the most spectacular displays of lightning on the planet. Lightning activity within volcanic plumes can be sensed remotely using systems such as the United Kingdom Met Office long-range lightning detection network, ATDnet, which recorded over 16 000 lightning strokes during the 2011 Grimsvötn eruption in Iceland. These remote sensing techniques can only be fully exploited if the charging mechanisms in volcanic plumes are well understood. Although the exact details of ash charging processes will vary from one eruption to another, triboelectrification, fractoemission, and the ''dirty thunderstorm'' mechanism are all thought to play a role in the electrification of ash near the vent. In addition to near-vent charging, observations show that charging can also occur in volcanic plumes up to hundreds of kilometres from the source region. The sustained nature of this charge in the presence of electrically conducting air suggests that a self-charging mechanism through the action of ash-to-ash contact charging (triboelectrification), may also play a role in the electrification of volcanic ash. This work describes a laboratory investigation into triboelectric charging of ash from the 2010 and 2011 volcanic eruptions of Eyjafjallajökull and Grímsvötn in Iceland respectively. Consistently with previous work, we find that the particle size distribution plays an important role in the magnitude of charging generated, specifically in terms of the normalized span of the particle size distribution. As well as triboelectrificiation, natural radioactivity in some volcanic ash could also contribute to self-charging of volcanic plumes, which is also examined here.

  20. High-MgO Vitric Ash in Upper Kulanaokuaiki Tephra, Kilauea Volcano, Hawai`i: A Preliminary Description

    NASA Astrophysics Data System (ADS)

    Rose, T. R.; Fiske, R. S.; Swanson, D.

    2011-12-01

    Small, well-formed Pele's tears containing anomalously high values of MgO were recently discovered in outcrops of the upper Kulanaokuaiki Tephra at and near the base of Uwekahuna Bluff, the western wall of Kilauea Caldera. Electron microprobe analyses of more than 60 high-MgO tears, which are 1-3 mm in diameter, show that most contain 11 to 12 wt. % MgO with a few approaching 13 % MgO. Separate microprobe analyses for sulfur and chlorine of 20 grains revealed no appreciable amounts of either, indicating the magma was largely degassed. Polished-section studies employing an analytical scanning electron microscope show most tears are composed of pure microvesicular glass with scattered skeletal olivine crystals and rare chromite. The abundance of skeletal olivine appears to increase with decreasing MgO content of the glass. These tears contain among the highest known MgO values of any material erupted subaerially from Kilauea. The high-MgO tears occur in a 1-6 cm thick layer of medium-coarse lithic-crystal-vitric ash. The top of this layer consists of 2-3 mm of very fine lithic-crystal ash. The lithics and many of the olivine crystals in this layer are highly oxidized. This deposit is at the top of a sequence of several lithic beds that are interspersed with thinner vitric units totaling about 75 cm in thickness. It is overlain by 9-13 cm of medium pumice lapilli and coarse vitric ash at the top of the "Bluff base" and "mid-Bluff" tephra sections described by Fiske et al. (2009). This high-MgO glass layer has been found thus far in only one other locality, a 2 m-deep soils study pit within Kipuka Puaulu, 3.5 km northwest of the caldera. Based upon stratigraphic relationships and preliminary microprobe data, a few other likely exposures of the high-MgO deposit have been identified north and west of the caldera. The high-MgO vitric ash in the upper Kulanaokuaiki Tephra has a primitive composition that suggests little if any shallow level storage of magma. Instead, the

  1. Soil Accretionary Dynamics, Sea-Level Rise and the Survival of Wetlands in Venice Lagoon: A Field and Modelling Approach

    NASA Astrophysics Data System (ADS)

    Day, J. W.; Rybczyk, J.; Scarton, F.; Rismondo, A.; Are, D.; Cecconi, G.

    1999-11-01

    Over the past century, Venice Lagoon (Italy) has experienced a high rate of wetland loss. To gain an understanding of the factors leading to this loss, from March 1993 until May 1996 the soil accretionary dynamics of these wetlands were studied. Vertical accretion, short term sedimentation, soil vertical elevation change and horizontal shoreline change were measured at several sites with varying sediment availability and wave energy. Short term sedimentation averaged 3-7 g dry m -2day -1per site with a maximum of 76 g m -2 day -1. The highest values were measured during strong pulsing events, such as storms and river floods, that mobilized and transported suspended sediments. Accretion ranged from 2-23 mm yr -1and soil elevation change ranged from -32 to 13·8 mm yr -1. The sites with highest accretion were near a river mouth and in an area where strong wave energy resuspended bottom sediments that were deposited on the marsh surface. A marsh created with dredged spoil had a high rate of elevation loss, probably due mainly to compaction. Shoreline retreat and expansion of tidal channels also occurred at several sites due to high wave energy and a greater tidal prism. The current rate of elevation gain at some sites was not sufficient to offset relative sea-level rise. The results suggest that reduction of wave energy and increasing sediment availability are needed to offset wetland loss in different areas of the lagoon. Using the data collected as part of this project, we developed a wetland elevation model designed to predict the effect of increasing rates of eustatic sea-level rise on wetland sustainability. The advantage of this model, in conjunction with measured short-term rates of soil elevation change, to determine sustainability is that the model integrates the effects of long term processes (e.g. compaction and decomposition) and takes into account feedback mechanisms that affect elevation. Specifically, changes in elevation can result in changes in

  2. Drilling into the deep interior of the Nankai accretionary prism: Preliminary results of IODP NanTroSEIZE Expedition 348

    NASA Astrophysics Data System (ADS)

    Tobin, H. J.; Hirose, T.; Saffer, D. M.; Toczko, S.; Maeda, L.

    2014-12-01

    International Ocean Discovery Program (IODP) Expedition 348, the latest advance of the NanTroSEIZE project, started on 13 September 2013 and was completed on 29 January 2014. During Expedition 348, the drilling vessel Chikyu advanced the ultra-deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula, from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf, the world record for the deepest scientific ocean drilling, and cased it for future deepening. The drilling operation successfully obtained data on formation physical properties from logging while drilling (LWD) tools, as well as from lithological analyses of cuttings and core from the interior of the active accretionary prism at the Nankai Trough. IODP Site C0002 is the currently only borehole to access the deep interior of an active convergent margin. Preliminary scientific results of Expedition 348 are as follows: (1) Fine-grained turbiditic mudstones with coarser silty and sandy interbeds, exhibiting steep dips (between ~60 and 90 degrees) are predominant in the prism down to ~3000 mbsf. The biostratigraphic age of the sediments in the lowermost part of the hole is thought to be 9-11 Ma, with an assumed age of accretion of 3-5 Ma. (2) Slickenlined surfaces, deformation bands and mineral veins are present throughout the drilled interval, while well-developed scaly clay fabrics are increasingly observed below ~2200 mbsf. A substantial fault zone with well-developed foliation was successfully cored from the deep interior of the prism at ~2205 mbsf. (3) Porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf. However, physical properties including grain density, electrical conductivity and P-wave velocity suggest fairly homogeneous properties in the interior of the prism between ~2000 and 3000 mbsf. (4) Mud gas analysis during the riser drilling indicates that a source of methane gas shifts from microbial origin to thermogenic at around 2325 mbsf. (5) The maximum

  3. Seafloor distribution and last glacial to postglacial activity of mud volcanoes on the Calabrian accretionary prism, Ionian Sea

    NASA Astrophysics Data System (ADS)

    Ceramicola, Silvia; Praeg, Daniel; Cova, Andrea; Accettella, Daniela; Zecchin, Massimo

    2014-06-01

    Mud volcanoes (MVs) are abundant along the eastern Mediterranean subduction zones, recording mud breccia extrusion over long timescales (106 years), but to date relatively few have been recognised in the northern Ionian Sea on the Calabrian accretionary prism (CAP). In the present study, the seafloor distribution and recent activity of MVs is investigated across a 35,600 km2 sector of the CAP using a regional acoustic dataset (multibeam bathymetric and backscatter imagery, integrated with subbottom profiles) locally ground-truthed by sediment cores. A total of 54 MVs are identified across water depths of 150-2,750 m using up to four geophysical criteria: distinctive morphology, high backscatter, unstratified subbottom facies and, in one case, a hydroacoustic flare. Fourteen MVs are identified from 3-4 criteria, of which five have been previously proven by cores containing mud breccia beneath up to 1.6 m of hemipelagic sediments (Madonna dello Ionio MVs 1-3, Pythagoras MV and the newly named Sartori MV), while nine others are identified for the first time (Athena, Catanzaro, Cerere, Diana, Giunone, Minerva, `right foot', Venere 1 and 2). Forty other as yet unnamed MVs are inferred from 1-2 geophysical criteria (three from distinctive morphology alone). All but one possible MV lie on the inner plateau of the CAP, landwards of the Calabrian Escarpment in a zone up to 120 km wide that includes the inner pre-Messinian wedge and the fore-arc basins, where they are interpreted to record the ascent from depth of overpressured fluids that interacted with tectonic structures and with evaporitic or shale seals within the fore-arc basins. The rise of fluids may have been triggered by post-Messinian out-of-sequence tectonism that affected the entire pre-Messinian prism, but Plio-Quaternary sedimentation rates and depositional styles support the inference that significant mud volcanism has taken place only on the inner plateau. Sedimentation rates across the CAP applied to a 12

  4. Middle Jurassic oceanic island igneous rocks of the Raohe accretionary complex, northeastern China: Petrogenesis and tectonic implications

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Hui; Ge, Wen-Chun; Yang, Hao; Zhang, Yan-Long; Bi, Jun-Hui; Tian, De-Xin; Xu, Wen-Liang

    2015-11-01

    Whole-rock major and trace element, and Sr, Nd, and Hf isotopic data, together with zircon U-Pb ages and in situ zircon Hf isotopes, are reported for Middle Jurassic igneous rocks of the Raohe accretionary complex, northeastern China, to investigate their petrogenesis and tectonic implications. The igneous rocks consist of pillow basalt, pyroxenite, gabbro, plagioclasite, and plagiogranite. The zircons from one plagioclasite and one plagiogranite are euhedral-subhedral and display fine-scale oscillatory growth zoning, indicating a magmatic origin. Zircon U-Pb dating gives an emplacement age of 169-167 Ma. The basalts are associated with late Paleozoic to middle Mesozoic sediments typical of ocean plate stratigraphy; i.e., limestone, bedded chert, and siliceous shale. The basalts, which show geochemical features similar to those of oceanic island basalts (OIBs), are enriched in TiO2, light rare earth elements (LREEs) (average: La/Smn = 2.12), and Nb (average: Zr/Nb = 12.24), and are characterized by positive Nb anomalies (averages: Nb/Thpm = 1.46, Nb/Lapm = 1.31). The rocks are depleted in heavy rare earth elements (HREEs) (average: Gd/Ybn = 2.03) and exhibit high εNd(t) (+8.2 to +8.3) and εHf(t) (+9.0 to +9.1) values. The geochemical features indicate the Jurassic OIB-like basalts were derived by a low degree of partial melting (<5%) of peridotite in the garnet stability field. The intermediate-mafic intrusive rocks show typical OIB affinities and are geochemically similar to the basalts. Most of the intermediate-mafic intrusive rocks are enriched in LREEs and Nb, depleted in HREEs, and show low Zr/Nb ratios and high εNd(t) (+7.2 to +8.2) and εHf(t) (+8.8 to +10.3) values, indicating they were derived from a common source and are the products of fractional crystallization of the OIB-like basalts. All of the igneous rocks are likely fragments of oceanic islands/seamounts. The identification of OIB-like basalts and associated intermediate-mafic intrusive rocks

  5. Accretionary history of the Altai-Mongolian terrane: perspectives from granitic zircon U-Pb and Hf-isotope data

    NASA Astrophysics Data System (ADS)

    Cai, Keda; Sun, Min; Xiao, Wenjiao

    2014-05-01

    which is likely due to basaltic magma that underplated the lower crust. Our data combined with evidence of the regional geology enable us to conclude that the Gorny Altai and Altai-Mongolian terranes possibly have similar tectonic natures, but represent two separate accretionary systems before Devonian collision. The accretion and amalgamation processes resulted in the Paleozoic granitoid magmatism and caused the two terranes to merge as a composite tectonic domain at the Siberian continental margin.

  6. Reconstructing the deadly eruptive events of 1790 CE at Kīlauea Volcano, Hawai‘i

    USGS Publications Warehouse

    Swanson, Don; Weaver, Samantha J; Houghton, Bruce F

    2014-01-01

    A large number of people died during an explosive eruption of Kīlauea Volcano in 1790 CE. Detailed study of the upper part of the Keanakāko‘i Tephra has identified the deposits that may have been responsible for the deaths. Three successive units record shifts in eruption style that agree well with accounts of the eruption based on survivor interviews 46 yr later. First, a wet fall of very fine, accretionary-lapilli–bearing ash created a “cloud of darkness.” People walked across the soft deposit, leaving footprints as evidence. While the ash was still unconsolidated, lithic lapilli fell into it from a high eruption column that was seen from 90 km away. Either just after this tephra fall or during its latest stage, pulsing dilute pyroclastic density currents, probably products of a phreatic eruption, swept across the western flank of Kīlauea, embedding lapilli in the muddy ash and crossing the trail along which the footprints occur. The pyroclastic density currents were most likely responsible for the fatalities, as judged from the reported condition and probable location of the bodies. This reconstruction is relevant today, as similar eruptions will probably occur in the future at Kīlauea and represent its most dangerous and least predictable hazard.

  7. Flue gas desulfurization gypsum and fly ash

    SciTech Connect

    Not Available

    1992-05-01

    The Cumberland Fossil Plant (CUF) is located in Stewart County, Tennessee, and began commercial operation in 1972. This is the Tennessee Valley Authority`s newest fossil (coal-burning) steam electric generating plant. Under current operating conditions, the plant burns approximately seven million tons of coal annually. By-products from the combustion of coal are fly ash, approximately 428,000 tons annually, and bottom ash, approximately 115,000 tons annually. Based on historical load and projected ash production rates, a study was initially undertaken to identify feasible alternatives for marketing, utilization and disposal of ash by-products. The preferred alternative to ensure that facilities are planned for all by-products which will potentially be generated at CUF is to plan facilities to handle wet FGD gypsum and dry fly ash. A number of different sites were evaluated for their suitability for development as FGD gypsum and ash storage facilities. LAW Engineering was contracted to conduct onsite explorations of sites to develop information on the general mature of subsurface soil, rock and groundwater conditions in the site areas. Surveys were also conducted on each site to assess the presence of endangered and threatened species, wetlands and floodplains, archaeological and cultural resources, prime farmland and other site characteristics which must be considered from an environmental perspective.

  8. Stabilization/solidification of TSCA incinerator ash

    SciTech Connect

    Spence, R.D.; Trotter, D.R.; Francis, C.L.; Morgan, I.L.

    1994-06-01

    Stabilization/solidification is a well-known waste treatment technique that utilizes different additives and processes. The Phoenix Ash Technology of the Technical Innovation Development Engineering Company is such a technique that uses Cass C fly ash and mechanical pressure to make brick waste forms out of solid wastes, such as the bottom ash from the Toxic Substances Control Act incinerator at the Oak Ridge K-25 Site. One advantage of this technique is that no volume increase over the bulk volume of the bottom ash occurs. This technique should have the same high pH stabilization for Resource Conservation and Recovery Act metals as similar techniques. Also, consolidation of the bottom ash minimizes the potential problems of material dispersion and container corrosion. The bottom ash was spiked with {sup 99}{Tc} to test the effectiveness of the bricks as a physical barrier. The {sup 99}{Tc} leachability index measured for these bricks was 6.8, typical for the pertechnetate anion in cementitious waste forms, indicating that these bricks have accessible porosity as high as that of other cementitious waste forms, despite the mechanical compression, higher waste form density, and water resistant polymer coating.

  9. Wildland fire ash: future research directions

    NASA Astrophysics Data System (ADS)

    Bodí, Merche B.; Martins, Deborah A.; Cerdà, Artemi; Balfour, Victoria N.; Santin, Cristina; Doerr, Stefan H.; Pereira, Paulo; Mataix-Solera, Jorge

    2014-05-01

    Ash is a key component of the forest fires affected land (Cerdà, 1998; Bodí et al., 2011; Pereira et al., 2013a). Ash controls the hydrological processes and determines the water repellency (Dlapa et al., 2012) and the infiltration rates (Cerdà and Doerr, 2008;). Moreover, ash is the key factor on runoff initiation and then on the soil erosion. Little is known about the impact of ash in different ecosystems, but during the last decade a substantial increase in the papers that show the role of ash in the Earth and Soil System were published (Bodí et al., 2012; Pereira et al., 2013b).. Ash is being found as the key component of the post-fire pedological, geomorphological and hydrological response after forest fires (Fernández et al., 2012; Martín et al., 2012; Bodí et al., 2013; Guénon et al., 2013; Pereira et al., 2013c). A recent State-of-the-Art review about wildland fire ash (Bodí et al., 2014) compiles the knowledge regarding the production, composition and eco-hydro-geomorphic effects of wildland fire ash. In the present paper we indicate the knowledge gaps detected and suggest topics that need more research effort concerning: i) data collection and analysis techniques: a) To develop standardized sampling techniques that allow cross comparison among sites and avoid inclusion of the underlying soil unless the burned surface soil forms part of the ash layer, b) To develop standardized methods to define and characterize ash, including its color, physical properties such as particle size distribution or density, proportion of pyrogenic C, chemical and biological reactivity and persistence in the environment, c) To validate, calibrate and test measurements collected through remote sensing with on-the-ground measurements. ii) ash production, deposition redistribution and fate: d) To untangle the significance of the effects of maximum temperature reached during combustion versus the duration of heating, e) To understand the production of ash by measuring its

  10. Use of fracture filling mineral assemblages for characterizing water-rock interactions during exhumation of an accretionary complex: An example from the Shimanto Belt, southern Kyushu Japan

    NASA Astrophysics Data System (ADS)

    Ono, Takuya; Yoshida, Hidekazu; Metcalfe, Richard

    2016-06-01

    Various fracture filling minerals and secondary minerals in fracture walls were formed by fluid-rock interaction during the exhumation of the Palaeogene Shimanto Belt of Kyushu, Japan, which is located in an accretionary complex. Each mineral formed under favourable geological conditions and can be used to estimate the conditions of accretion and formation of the related rock sequences. Petrographic observations, mineralogical and geochemical analyses were made on fracture filling minerals and secondary minerals from boreholes of ca. 140 m depth, drilled in the Shimanto Belt. Results reveal that the secondary minerals were formed in three major stages distinguished by the sequential textural relationships of the minerals and the interpreted environment of mineral formation. Filling mineral assemblages show that the studied rock formation has been subducted to a depth of several km and the temperature reached was ca. 200-300 °C. After the subduction, the rock formation was uplifted and surface acidic water penetrated up to 80 m beneath the present ground surface. The acid water dissolved calcite fracture filling minerals to form the present groundwater flow-paths, which allowed recent wall rock alteration to occur. The results shown here imply that filling mineral assemblages can be an effective tool to evaluate the environmental changes during exhumation of an accretionary complex.

  11. Fate of sediment during plate convergence at the Mediterranean Ridge accretionary complex: Volume balance of mud extrusion versus subduction and/or accretion

    NASA Astrophysics Data System (ADS)

    Kopf, Achim

    1999-01-01

    Drilling results from two mud volcanoes on the Mediterranean Ridge accretionary complex as well as extensive geophysical surveys have provided new insights about the geometry of these domes at depth. Mud extrusion is related to buoyancy and plate convergence between Africa and Eurasia that caused back-thrust faulting of accreted strata containing overpressured mud at depth. The domes mainly consist of mud breccia formed of as much as 65% polymictic clasts embedded in a clayey matrix of presumed late Miocene age. Volumetric estimates of extruded mud in a well-studied area around the Olimpi mud-volcano field were balanced against sediment input at the deformation front. The results demonstrate that only a small fraction of rock mass having entered the subduction zone since the Messinian is needed to compensate for the mud expelled in the study area. Most of the sediment (95% or more) is either subducted or incorporated into the accretionary prism. The volume of gas expelled with the liquefied, overpressured mud was estimated to range between 1.68 × 106 and 2.85 × 107 m3/yr.

  12. Neotethyan rifting-related ore occurrences: study of an accretionary mélange complex (Darnó Unit, NE Hungary)

    NASA Astrophysics Data System (ADS)

    Kiss, Gabriella B.; Oláh, Erika; Zaccarini, Federica; Szakáll, Sándor

    2016-02-01

    The geology of the NE Hungarian Darnó Unit is rather complicated, as it is composed mostly of a Jurassic accretionary mélange complex, according to the most recent investigations. The magmatic and sedimentary rock blocks of the mélange represent products of different evolutionary stages of the Neotethys; including Permian and Triassic sedimentary rocks of marine rifting related origin, Triassic pillow basalt of advanced rifting related origin and Jurassic pillow basalt originated in back-arc-basin environment. This small unit contains a copper-gold occurrence in the Permian marly-clayey limestone, an iron enrichment in the Triassic sedimentary succession, a copper-silver ore occurrence in Triassic pillow basalts and a copper ore indication, occurring both in the Triassic and Jurassic pillow basalts. The present study deals with the Cu(-Ag) occurrence in the Triassic basalt and the Fe occurrence in the Triassic sedimentary succession. The former shows significant similarities with the Michigan-type mineralizations, while the latter has typical characteristics of the Fe-SEDEX deposits. All the above localities fit well into the new geological model of the investigated area. The mineralizations represent the different evolutionary stages of the Neotethyan rifting and an epigenetic, Alpine metamorphism-related process and their recent, spatially close position is the result of the accretionary mélange formation. Thus, the Darnó Unit represents a perfect natural laboratory for studying and understanding the characteristic features of several different rifting related ore forming processes.

  13. Provenance analysis and detrital zircon geochronology on the onshore Makran accretionary wedge, SE Iran: implication for the geodynamic setting

    NASA Astrophysics Data System (ADS)

    Mohammadi, Ali; Burg, Jean-Pierre; Winkler, Wilfried; Ruh, Jonas

    2014-05-01

    The Makran, located in Southeast Iran and South Pakistan, is one of the largest accretionary wedges on Earth. In Iran it comprises turbiditic sediments ranging in age from Late Cretaceous to Holocene. We present a provenance analysis on sandstones, which is aimed at reconstructing the assemblages of source rocks and the tectonic setting from which the clastic material was derived. Sandstone samples collected from different units span the regional stratigraphy from Late Cretaceous to Miocene. Laser ablation ICP-MS resulted in ca 2800 new U-Pb ages of individual detrital zircons from 18 samples collected in onshore Makran. 101 detrital zircons from a Late Cretaceous fine grained sandstone range from 180 to 160 Ma (Middle Jurassic). 478 detrital zircons from mid- to late Eocene sandstones allow differentiating a NE and NW sector of the Makran Basin. Zircon grains in the NE basin belong to two populations peaking at 180 to 160 Ma (late Early to Middle Jurassic) and 50 to 40 Ma (Mid-Eocene), with the noticeable absence of Cretaceous grains. In the NW basin, detrital zircons are 120 to 40 Ma (late Early Cretaceous to Lutetian, Eocene). 587 detrital zircon grains from fine to medium grained Oligocene sandstones collected over the whole area also range from 120 to 40 Ma (late Early Cretaceous to Eocene, Lutetian). 1611 detrital zircons from early Miocene sandstones show again distinctly different ages in the eastern and western parts of the basin. They range from 120 to 40 Ma (late Early Cretaceous to Eocene) in the eastern and from 80 to 40 Ma (Late Cretaceous to Eocene) in the western basin. Hf isotopes analyses were performed on 120 zircon grains from 6 samples. Negative values (-2 to -15) in Middle Jurassic and late Early Cretaceous zircons indicate minor or no influence of mantle reservoirs which implies a rifting setting during crystallization of the zircons. Low negative to positive (-5 to +10) values in Late Cretaceous and Eocene zircons indicate mixed crustal and

  14. Tectonic implications for the occurrence of ocean floor, hotspot, and island arc materials within accretionary prisms: Examples from the Mesozoic-Cenozoic NW Pacific Rim

    NASA Astrophysics Data System (ADS)

    Ogawa, Y.; Hirano, N.; Hirano, N.; Taniguchi, H.; Taniguchi, H.; Taniguchi, H.

    2001-12-01

    On-land Mesozoic-Cenozoic accretionary prisms exposed in Japan commonly have basaltic rocks incorporated as blocks into melanges or fault zones during a prolonged history of subduction and/or obduction. Chemical signatures of these basaltic rocks and their mode of occurrence with sedimentary covers and/or associated sedimentary rocks indicate that most of these isolated small basaltic blocks consistently display a WPB chemistry, whereas large slabs of basaltic rocks around the Izu Arc collision zone show MORB chemistry with rare examples of IAT, BABB, and/or WPB affinities. Comparing with the present uniformitarian examples of convergent plate boundaries in the western Pacific that we know through the DSDP and ODP projects and submersible and seismic surveys, we can interpret some of the basaltic material with WPB affinity in the Japanese accretionary prisms as relict edifices of seamounts with hotspot origin. These hotspot-related basaltic rocks are commonly associated with reefal limestones and were incorporated into continental margin melanges either by submarine sliding from the downgoing oceanic plate or by shallow-level offscraping along decollement surfaces during the subduction of oceanic plates. Older, uplifted parts of the fossil accretionary prisms on the continent side further inward from the trench where the deeper levels of accreted material are exposed include larger amounts of basaltic blocks. This observation suggests that significant amount of underplating might have occurred in the deeper levels of oceanic crust along decollement zones at structurally lower depths. The metamorphic belts (e.g.Sambagawa, Chichibu, Shimanto etc.) have commonly alkaline rocks or plateau-type E-MORB basalts without any trace of N-MORB rocks with rare special exceptions. Besides these ordinary accretionary prism examples formed by a simple plate subduction system, another type of accretion resulting from island arc or ridge collision is observed to have occurred in

  15. Episodic vs. Continuous Accretion in the Franciscan Accretionary Prism and Direct Plate Motion Controls vs. More Local Tectonic Controls on Prism Evolution

    NASA Astrophysics Data System (ADS)

    Dumitru, T. A.; Ernst, W. G.; Wakabayashi, J.

    2011-12-01

    Subduction at the Franciscan trench began ≈170-165 Ma and continues today off Oregon-Washington. Plate motion reconstructions, high-P metamorphic rocks, and the arc magmatic record suggest that convergence and thus subduction were continuous throughout this period, although data for 170 to 120 Ma are less definitive. About 25% of modern subduction zones are actively building an accretionary prism, whereas 75% are nonaccretionary, in which subduction erosion is gradually removing the prism and/or forearc basement. These contrasting behaviors in modern subduction zones suggest that the Franciscan probably fluctuated between accretionary and nonaccretionary modes at various times and places during its 170 million year lifespan. Accumulating geochronologic data are beginning to clarify certain accretionary vs. nonaccretionary intervals. (1) The oldest Franciscan rocks are high-P mafic blocks probably metamorphosed in a subophiolitic sole during initiation of subduction. They yield garnet Lu-Hf and hornblende Ar/Ar ages from ≈169 to 147 Ma. Their combined volume is extremely small and much of the Franciscan was probably in an essentially nonaccretionary mode during this period. (2) The South Fork Mountain Schist forms the structural top of the preserved wedge in northern California and thus was apparently the first genuinely large sedimentary body to accrete. This occurred at ≈123 Ma (Ar/Ar ages), suggesting major accretion was delayed a full ≈45 million years after the initiation of subduction. The underlying Valentine Spring Fm. accreted soon thereafter. This shift into an accretionary mode was nearly synchronous with the end of the Early Cretaceous magmatic lull and the beginning of the prolonged Cretaceous intensification of magmatism in the Sierra Nevada arc. (3) The Yolla Bolly terrane has generally been assigned a latest Jurassic to earliest Cretaceous age. Detrital zircon data confirm that some latest Jurassic sandstones are present, but they may be

  16. Enhancing performance and durability of slag made from incinerator bottom ash and fly ash.

    PubMed

    Chiou, Ing-Jia; Wang, Kuen-Sheng; Tsai, Chen-Chiu

    2009-02-01

    This work presents a method capable of melting the incinerator bottom ash and fly ash in a plasma furnace. The performance of slag and the strategies for recycling of bottom ash and fly ash are improved by adjusting chemical components of bottom ash and fly ash. Ashes are separated by a magnetic process to improve the performance of slag. Analytical results indicate that the air-cooled slag (ACS) and magnetic-separated slag (MSS) have hardness levels below 590 MPa, indicating fragility. Additionally, the hardness of crystallized slag (RTS) is between 655 and 686 MPa, indicating toughness. The leached concentrations of heavy metals for these three slags are all below the regulatory limits. ACS appears to have better chemical stability than MSS, and is not significantly different from RTS. In the potential alkali-silica reactivity of slag, MSS falls on the border between the harmless zone and the potentially harmful zone. ACS and RTS fall in the harmless zone. Hence, the magnetic separation procedure of ashes does not significantly improve the quality of slag. However, RTS appears to improve its quality. PMID:18544471

  17. Comparative study on the characteristics of fly ash and bottom ash geopolymers.

    PubMed

    Chindaprasirt, Prinya; Jaturapitakkul, Chai; Chalee, Wichian; Rattanasak, Ubolluk

    2009-02-01

    This research was conducted to compare geopolymers made from fly ash and ground bottom ash. Sodium hydroxide (NaOH) and sodium silicate (Na(2)SiO(3)) solutions were used as activators. A mass ratio of 1.5 Na(2)SiO(3)/NaOH and three concentrations of NaOH (5, 10, and 15M) were used; the geopolymers were cured at 65 degrees C for 48 h. A Fourier transform infrared spectrometer (FT-IR), differential scanning calorimeter (DSC), and scanning electron microscope (SEM) were used on the geopolymer pastes. Geopolymer mortars were also prepared in order to investigate compressive strength. The results show that both fly ash and bottom ash can be utilized as source materials for the production of geopolymers. The properties of the geopolymers are dependent on source materials and the NaOH concentration. Fly ash is more reactive and produces a higher degree of geopolymerization in comparison with bottom ash. The moderate NaOH concentration of 10 M is found to be suitable and gives fly ash and bottom ash geopolymer mortars with compressive strengths of 35 and 18 MPa.

  18. Comparative study on the characteristics of fly ash and bottom ash geopolymers

    SciTech Connect

    Chindaprasirt, Prinya; Jaturapitakkul, Chai; Chalee, Wichian; Rattanasak, Ubolluk

    2009-02-15

    This research was conducted to compare geopolymers made from fly ash and ground bottom ash. Sodium hydroxide (NaOH) and sodium silicate (Na{sub 2}SiO{sub 3}) solutions were used as activators. A mass ratio of 1.5 Na{sub 2}SiO{sub 3}/NaOH and three concentrations of NaOH (5, 10, and 15 M) were used; the geopolymers were cured at 65 deg. C for 48 h. A Fourier transform infrared spectrometer (FT-IR), differential scanning calorimeter (DSC), and scanning electron microscope (SEM) were used on the geopolymer pastes. Geopolymer mortars were also prepared in order to investigate compressive strength. The results show that both fly ash and bottom ash can be utilized as source materials for the production of geopolymers. The properties of the geopolymers are dependent on source materials and the NaOH concentration. Fly ash is more reactive and produces a higher degree of geopolymerization in comparison with bottom ash. The moderate NaOH concentration of 10 M is found to be suitable and gives fly ash and bottom ash geopolymer mortars with compressive strengths of 35 and 18 MPa.

  19. Scale-Up and Demonstration of Fly Ash Ozonation Technology

    SciTech Connect

    Rui Afonso; R. Hurt; I. Kulaots

    2006-03-01

    The disposal of fly ash from the combustion of coal has become increasingly important. When the fly ash does not meet the required specification for the product or market intended, it is necessary to beneficiate it to achieve the desired quality. This project, conducted at PPL's Montour SES, is the first near full-scale ({approx}10 ton/day), demonstration of ash ozonation technology. Bituminous and sub bituminous ashes, including two ash samples that contained activated carbon, were treated during the project. Results from the tests were very promising. The ashes were successfully treated with ozone, yielding concrete-suitable ash quality. Preliminary process cost estimates indicate that capital and operating costs to treat unburned carbon are competitive with other commercial ash beneficiation technologies at a fraction of the cost of lost sales and/or ash disposal costs. This is the final technical report under DOE Cooperative Agreement No.: DE-FC26-03NT41730.

  20. Power plant ashes and their utilization. Part 10. Summary

    SciTech Connect

    Eerola, M.; Keppo, M.; Korkman, J.; Kukko, H.; Vanhanen, A.

    1980-01-01

    For fine-grained fly ash and coarser-grained bottom ash originating from power plants as combustion residue a profitable use for many purposes has already been found. Many European countries utilize great amounts of ashes they produce. The quality of ash is dependent on the fuel used and the equipment of the power plant in question. The building industry utilizes plenty of fine-grained materials with many features closely resembling fly ash. In lightweight aggregate production it is possible to use fly ash for improving the strength level of a product or lightweight aggregate particles can be sintered from fly ash and water without using clay. For the manufacture of bricks fly and bottom ashes have been used abroad as a material replacing sand and silt or as such mixed together. In road construction, fly ash is suitable for use as an embankment fill and a stabilized structure for subbases and base courses or as a filler for asphalt pavements. For the purposes of fertilization and soil improvement highly nutrient ashes (sulphite liquor, wood, peat) can be utilized. The use of ashes as a raw material e.g. in metal industry has started to attract attention abroad. Practical problems pertaining to the utilization of ashes are: the varying production rate due to the succession of the seasons, transportation and transfer of dry ashes, and arrangement of the quality control. The above mentioned factors result in expenses but also saving is brought about by using ashes.

  1. Insight of the fusion behavior of volcanic ash: Implications for Volcanic ash Hazards to Aircraft Safety

    NASA Astrophysics Data System (ADS)

    Song, Wenjia; Hess, Kai-Uwe; Küppers, Ulrich; Scheu, Bettina; Cimarelli, Corrado; Lavallée, Yan; Sohyun, Park; Gattermann, Ulf; Müller, Dirk; Dingwell, Donald Bruce

    2014-05-01

    The interaction of volcanic ash with jet turbines during via ingestion of ash into engines operating at supra-volcanic temperatures is widely recognized as a potentially fatal hazard for jet aircraft. In the past 12 years, more than 60 modern jet airplanes, mostly jumbo jets, have been damaged by drifting clouds of volcanic ash that have contaminated air routes and airport facilities. Seven of these encounters are known to have caused in flight loss of engine power to jumbo jets carrying a total of more than 2000 passengers. The fusibility of volcanic ash is believed to impact strongly its deposition in the hotter parts of jet engines. Despite this, explicit investigation of ash sintering using standardized techniques is in its infancy. Volcanic ash may vary widely in its physical state and chemical composition between and even within explosive volcanic eruptions. Thus a comparative study of the fusibility of ash which involves a standard recognized techniques would be highly desirable. In this work, nine samples of fine ash, deposited from co-pyroclastic offrom nine different volcanoes which cover a broad range of chemical composition, were investigated. Eight of them were collected from 2001-2009 eruptions. Because of the currently elevated level of eruptive activity and its potential hazards to aircraft safety and the remaining one sample was collected from a 12,121 ± 114 yr B.P. eruption. We used the method of accessing the behavior of deposit-forming impurities in high temperature boiler plants on the basis of observations of the change in shape and size of a cylindrical coal ash to study the fusion phenomena as well as determine the volcanic ash melting behavior by defining four characteristic temperatures (shrinkage temperature, deformation temperature, hemispherical temperature, and flow temperature) by means of heating microscope instrument and different thermal analysis methods. Here, we find that there are similar sticking ability and flow behavior of

  2. International Database of Volcanic Ash Impacts

    NASA Astrophysics Data System (ADS)

    Wallace, K.; Cameron, C.; Wilson, T. M.; Jenkins, S.; Brown, S.; Leonard, G.; Deligne, N.; Stewart, C.

    2015-12-01

    Volcanic ash creates extensive impacts to people and property, yet we lack a global ash impacts catalog to organize, distribute, and archive this important information. Critical impact information is often stored in ephemeral news articles or other isolated resources, which cannot be queried or located easily. A global ash impacts database would improve 1) warning messages, 2) public and lifeline emergency preparation, and 3) eruption response and recovery. Ashfall can have varying consequences, such as disabling critical lifeline infrastructure (e.g. electrical generation and transmission, water supplies, telecommunications, aircraft and airports) or merely creating limited and expensive inconvenience to local communities. Impacts to the aviation sector can be a far-reaching global issue. The international volcanic ash impacts community formed a committee to develop a database to catalog the impacts of volcanic ash. We identify three user populations for this database: 1) research teams, who would use the database to assist in systematic collection, recording, and storage of ash impact data, and to prioritize impact assessment trips and lab experiments 2) volcanic risk assessment scientists who rely on impact data for assessments (especially vulnerability/fragility assessments); a complete dataset would have utility for global, regional, national and local scale risk assessments, and 3) citizen science volcanic hazard reporting. Publication of an international ash impacts database will encourage standardization and development of best practices for collecting and reporting impact information. Data entered will be highly categorized, searchable, and open source. Systematic cataloging of impact data will allow users to query the data and extract valuable information to aid in the development of improved emergency preparedness, response and recovery measures.

  3. Isotopic paleoclimate from hydrated volcanic ash

    SciTech Connect

    Friedman, I.; Izett, G.A.; Gleason, J.D.

    1985-01-01

    The deuterium composition (deltaD) of secondary water in glass shards of volcanic ash can be used to calculate the deltaD--and hence the climatic association--of water that was in contact with the ash during the first 10,000 years after eruption of the ash; this being the approximate (+/-5000 years) time necessary for water to diffuse completely through the thin walls of the pumice and glass shards. The fractionation between environmental water and water diffusing into the glassy ash must be known in order to calculate the deltaD of the ancient ground water. With help from A.J. Gude and R.A. Sheppard, the authors have recently determined this fractionation, and have used it to derive a value for deltaD of water from 25 samples of glass from the Huckleberry Ridge (2.1 m.y.), Bishop Tuff (0.74 m.y.), and Lava Creek B (0.61 m.y.) ashes collected from sites throughout the Western US. All of these deltaD values correlate very well with latitude and with the present distribution of deltaD in surface water. For example, the deltaD of water in Huckleberry Ridge ash varies from -85 per thousand SMOW for samples collected in Texas, to -148 per thousand for samples from south-central Montana. Thus, water of hydration in rhyolitic ash represents samples of ancient environmental water and can be used to study changes in the deltaD of the precipitation through time.

  4. Analysis of municipal refuse incinerator ashes for asbestos

    SciTech Connect

    Patel-Mandlik, K.J.; Manos, C.G.; Lisk, D.J.

    1988-12-01

    The ash which results from incineration includes bottom ash (slag) and fly ash, the latter being trapped in electrostatic precipitators or fabric filtration systems (baghouses, etc.). These ashes are collected separately or mixed and usually disposed in secure landfills with or without prior recovery of reusable metals. Whereas many published surveys have dealt with the concentrations of heavy metals and toxic organics in such ashes, very little has been reported on the possible presence of asbestos in them. In the work reported here, an analytical survey was conducted of the possible presence of asbestos in 20 such ashes from 18 incinerators in the United States.

  5. Marine Mesocosm Bacterial Colonisation of Volcanic Ash

    NASA Astrophysics Data System (ADS)

    Witt, V.; Cimarelli, C.; Ayris, P. M.; Kueppers, U.; Erpenbeck, D.; Dingwell, D. B.; Woerheide, G.

    2014-12-01

    Explosive volcanic eruptions regularly eject large quantities of ash particles into the atmosphere, which can be deposited via fallout into oceanic environments. Such fallout has the potential to alter pH, light and nutrient availability at local or regional scales. Shallow-water coral reef ecosystems - "rainforests of the sea" - are highly sensitive to disturbances, such as ocean acidification, sedimentation and eutrophication. Therefore, ash deposition may lead to burial and mortality of such reefs. Coral reef ecosystem resilience may depend on pioneer bacterial colonisation of the ash layer, supporting subsequent establishment of the micro- and ultimately the macro-community. However, it is currently unknown which bacteria are involved in pioneer colonisation. We hypothesize that physico-chemical properties (i.e., morphology, chemistry, mineralogy) of the ash may dictate bacterial colonisation. We have tested the effect of substrate properties on bacterial diversity and abundance colonising five substrates: i) quartz sand ii) crystalline ash from the Sakurajima volcano (Japan) iii) volcanic glass iv) carbonate reef sand and v) calcite sand of similar grain size - by incubation in a controlled marine mesocosm (coral reef aquarium) under low light conditions for three months. Bacterial communities were screened every month by Automated Ribosomal Intergenic Spacer Analysis of the 16S-23S rRNA Internal Transcribed Spacer region. Multivariate statistics revealed discrete groupings of bacterial communities on substrates of volcanic origin (ash and glass) and reef origin (three sands). Analysis Of Similarity supports significantly different communities associated with all substrates (p=0.0001), only quartz did not differ from both carbonate and calcite sands. The ash substrate exhibited the most diverse bacterial community and carried the most substrate-specific bacterial operational taxonomic units. Our findings suggest that bacterial diversity and community

  6. Hydrothermal reaction of fly ash. Final report

    SciTech Connect

    Brown, P.W.

    1994-12-31

    The reactions which occur when fly ash is treated under hydrothermal conditions were investigated. This was done for the following primary reasons. The first of these is to determine the nature of the phases that form to assess the stabilities of these phases in the ambient environment and, finally, to assess whether these phases are capable of sequestering hazardous species. The second reason for undertaking this study was whether, depending on the composition of the ash and the presence of selected additives, it would be possible under hydrothermal conditions to form compounds which have cementitious properties. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, were selected for study. The classes are calcium silicate hydrates, calcium selenates, and calcium aluminosulfates, and silicate-based glasses. Specific compounds synthesized were determined and their stability regions assessed. As part of stability assessment, the extent to which selected hazardous species are sequestered was determined. Finally, the cementing properties of these compounds were established. The results obtained in this program have demonstrated that mild hydrothermal conditions can be employed to improve the reactivity of fly ash. Such improvements in reactivity can result in the formation of monolithic forms which may exhibit suitable mechanical properties for selected applications as building materials. If the ashes involved are considered hazardous, the mechanical properties exhibited indicated the forms could be handled in a manner which facilitates their disposal.

  7. National volcanic ash operations plan for aviation

    USGS Publications Warehouse

    ,; ,

    2007-01-01

    The National Aviation Weather Program Strategic Plan (1997) and the National Aviation Weather Initiatives (1999) both identified volcanic ash as a high-priority informational need to aviation services. The risk to aviation from airborne volcanic ash is known and includes degraded engine performance (including flameout), loss of visibility, failure of critical navigational and operational instruments, and, in the worse case, loss of life. The immediate costs for aircraft encountering a dense plume are potentially major—damages up to $80 million have occurred to a single aircraft. Aircraft encountering less dense volcanic ash clouds can incur longer-term costs due to increased maintenance of engines and external surfaces. The overall goal, as stated in the Initiatives, is to eliminate encounters with ash that could degrade the in-flight safety of aircrews and passengers and cause damage to the aircraft. This goal can be accomplished by improving the ability to detect, track, and forecast hazardous ash clouds and to provide adequate warnings to the aviation community on the present and future location of the cloud. To reach this goal, the National Aviation Weather Program established three objectives: (1) prevention of accidental encounters with hazardous clouds; (2) reduction of air traffic delays, diversions, or evasive actions when hazardous clouds are present; and (3) the development of a single, worldwide standard for exchange of information on airborne hazardous materials. To that end, over the last several years, based on numerous documents (including an OFCMsponsored comprehensive study on aviation training and an update of Aviation Weather Programs/Projects), user forums, and two International Conferences on Volcanic Ash and Aviation Safety (1992 and 2004), the Working Group for Volcanic Ash (WG/VA), under the OFCM-sponsored Committee for Aviation Services and Research, developed the National Volcanic Ash Operations Plan for Aviation and Support of the

  8. Interspecific Proteomic Comparisons Reveal Ash Phloem Genes Potentially Involved in Constitutive Resistance to the Emerald Ash Borer

    PubMed Central

    Whitehill, Justin G. A.; Popova-Butler, Alexandra; Green-Church, Kari B.; Koch, Jennifer L.; Herms, Daniel A.; Bonello, Pierluigi

    2011-01-01

    The emerald ash borer (Agrilus planipennis) is an invasive wood-boring beetle that has killed millions of ash trees since its accidental introduction to North America. All North American ash species (Fraxinus spp.) that emerald ash borer has encountered so far are susceptible, while an Asian species, Manchurian ash (F. mandshurica), which shares an evolutionary history with emerald ash borer, is resistant. Phylogenetic evidence places North American black ash (F. nigra) and Manchurian ash in the same clade and section, yet black ash is highly susceptible to the emerald ash borer. This contrast provides an opportunity to compare the genetic traits of the two species and identify those with a potential role in defense/resistance. We used Difference Gel Electrophoresis (DIGE) to compare the phloem proteomes of resistant Manchurian to susceptible black, green, and white ash. Differentially expressed proteins associated with the resistant Manchurian ash when compared to the susceptible ash species were identified using nano-LC-MS/MS and putative identities assigned. Proteomic differences were strongly associated with the phylogenetic relationships among the four species. Proteins identified in Manchurian ash potentially associated with its resistance to emerald ash borer include a PR-10 protein, an aspartic protease, a phenylcoumaran benzylic ether reductase (PCBER), and a thylakoid-bound ascorbate peroxidase. Discovery of resistance-related proteins in Asian species will inform approaches in which resistance genes can be introgressed into North American ash species. The generation of resistant North American ash genotypes can be used in forest ecosystem restoration and urban plantings following the wake of the emerald ash borer invasion. PMID:21949771

  9. Interspecific proteomic comparisons reveal ash phloem genes potentially involved in constitutive resistance to the emerald ash borer.

    PubMed

    Whitehill, Justin G A; Popova-Butler, Alexandra; Green-Church, Kari B; Koch, Jennifer L; Herms, Daniel A; Bonello, Pierluigi

    2011-01-01

    The emerald ash borer (Agrilus planipennis) is an invasive wood-boring beetle that has killed millions of ash trees since its accidental introduction to North America. All North American ash species (Fraxinus spp.) that emerald ash borer has encountered so far are susceptible, while an Asian species, Manchurian ash (F. mandshurica), which shares an evolutionary history with emerald ash borer, is resistant. Phylogenetic evidence places North American black ash (F. nigra) and Manchurian ash in the same clade and section, yet black ash is highly susceptible to the emerald ash borer. This contrast provides an opportunity to compare the genetic traits of the two species and identify those with a potential role in defense/resistance. We used Difference Gel Electrophoresis (DIGE) to compare the phloem proteomes of resistant Manchurian to susceptible black, green, and white ash. Differentially expressed proteins associated with the resistant Manchurian ash when compared to the susceptible ash species were identified using nano-LC-MS/MS and putative identities assigned. Proteomic differences were strongly associated with the phylogenetic relationships among the four species. Proteins identified in Manchurian ash potentially associated with its resistance to emerald ash borer include a PR-10 protein, an aspartic protease, a phenylcoumaran benzylic ether reductase (PCBER), and a thylakoid-bound ascorbate peroxidase. Discovery of resistance-related proteins in Asian species will inform approaches in which resistance genes can be introgressed into North American ash species. The generation of resistant North American ash genotypes can be used in forest ecosystem restoration and urban plantings following the wake of the emerald ash borer invasion.

  10. Continental Margin of Kamchatka Peninsula, Russia: the Mode and Nature of Crustal Growth in the Accretionary Orogen

    NASA Astrophysics Data System (ADS)

    Konstantinovskaya, E. A.; Bindeman, I. N.

    2001-12-01

    Tectonic accretion of island arc terranes is the process widely developed in Pacific Rim in the present and in the past. The mode and nature of crustal growth of continental margins during arc accretion are various and essentially determined by deformation of the margin. The Cenozoic Kamchatka orogen formed by the accretion of two island arc terranes: Achaivayam-Valaginskaya arc (A-V, Eocene) (2) and Kronotskaya arc (terminal Miocene) to the continental margin of Asia. During the Early Eocene, the southern segment of the A-V arc collided with the Sredinny metamorphic massif, which was the frontal part of the Asian continental margin (3). New results from SHRIMP dating of zircons (1) from metamorphic rocks of Sredinny massif (Kolpakovskaya series) show that the massif contains an abundance of Archean, Proterozoic and Phanerozoic detrital zircon cores, and ubiquitous 77 Ma rims. The youngest ages are from four 47-53 Ma unzoned zircon cores, with dull cathodoluminescence, and irregular morphology. We regard the 47-53 Ma episode of zircon growth in the Sredinny massif as evidence for superimposed metamorphism induced by continental margin subduction at the beginning of its collision with the A-V arc in the early Eocene. Physical modeling experiments of arc-continent collision suggest that deformation at continental margin is controlled by strength of the subducting crust. Failure, accretion and erosion-activated extrusion/exhumation of the subducted crust occur in the continental margin in the case when the margin is weakened by pre-existing faulting, extension, or heating. At the beginning of the continental margin subduction, crust of the margin fails along the continent-vergent thrust. The subducted crustal slice is, then, completely scraped from the mantle base and accreted to the fore-arc block. Subsequent thrusting and thickening of the subducting crust within the continental margin lead to formation of the accretionary orogen composed of crustal slices in front

  11. Rock magnetic properties of dusty olivine: a potential carrier of pre-accretionary remanence in unequilibrated ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Lappe, S. C. L. L.; Harrison, R. J.; Feinberg, J. M.

    2012-04-01

    The mechanism of chondrule formation is an important outstanding question in cosmochemistry. Magnetic signals recorded by Fe-Ni nanoparticles in chondrules could carry clues to their origin. Recently, research in this area has focused on 'dusty olivine' grains within ordinary chondrites as potential carriers of pre-accretionary remanence. Dusty olivine is characterised by the presence of sub-micron Fe-Ni inclusions within the olivine host. These metal particles form via subsolidus reduction of the olivine during chondrule formation and are thought to be protected from subsequent chemical and thermal alteration by the host olivine. Three sets of synthetic dusty olivines have been produced, using natural olivine (average Ni-content of 0.3 wt%), synthetic Ni-containing olivine (0.1wt% Ni) and synthetic Ni-free olivine as starting materials. The starting materials were ground to powders, packed into a 2-3 mm3 graphite crucible, heated up to 1350 °C under a pure CO gas flow and kept at this temperature for 10 minutes. After this the samples were held in a fixed orientation and quenched into water in a range of known magnetic fields, ranging from 0.2 mT to 1.5 mT. We present here for the first time an analysis of a new FORC-based method of paleointensity determination applied to metallic Fe-bearing samples [1, 2]. The method uses a first-order reversal curve (FORC) diagram to generate a Preisach distribution of coercivities and interaction fields within the sample and then physically models the acquisition of TRM as a function of magnetic field, temperature and time using thermal relaxation theory. The comparison of observed and calculated NRM demagnetisation spectra is adversely effected by a large population of particles in the single-vortex state. Comparison of observed and calculated REM' curves, however, yields much closer agreement in the high-coercivity SD-dominated range. Calculated values of the average REM' ratio show excellent agreement with the experimental

  12. Geology and petrology of the Woods Mountains Volcanic Center, southeastern California: Implications for the genesis of peralkaline rhyolite ash flow tuffs

    NASA Astrophysics Data System (ADS)

    McCurry, Michael

    1988-12-01

    The Woods Mountains Volcanic Center is a middle Miocene silicic caldera complex located at the transition from the northern to the southern Basin and Range provinces of the western United States. It consists of a trachyte-trachydacite-rhyolite-peralkaline rhyolite association of lava flows, domes, plugs, pyroclastic rocks, and epiclastic breccia. Volcanism began at about 16.4 Ma, near the end of a local resurgence of felsic to intermediate magmatism and associated crustal extension. Numerous metaluminous high-K trachyte, trachydacite, and rhyolite lava flows, domes, and pyroclastic deposits accumulated from vents scattered over an area of 200 km2 forming a broad volcanic field with an initial volume of about 10 km3. At 15.8 Ma, about 80 km3 of metaluminous to mildly peralkaline high-K rhyolite ash flows were erupted from vents in the western part of fhe field in three closely spaced pulses, resulting in the formation of a trap door caldera 10 km in diameter. The ash flows formed the Wild Horse Mesa Tuff, a compositionally zoned ash flow sheet that originally covered an area of about 600 km2 to a maximum thickness of at least 320 m. High-K trachyte pumice lapilli, some of which are intimately banded with rhyolite, were produced late in the two later eruptions, Intracaldera volcanism from widely distributed vents rapidly filled the caldera with about 10 km3 of high-K, mildly peralkaline, high-silica rhyolite lava flows and pyroclastic deposits. These are interlayered with breccia derived from the caldera scarp. They are intruded by numerous compositionally similar plugs, some of which structurally uplifted and fractured the center of the caldera. The center evolved above a high-K trachyte magma chamber about 10 km in diameter that had developed and differentiated within the upper crust at about 15.8 Ma. Petrological, geochemical, and geophysical data are consistent with the idea that a cap of peralkaline rhyolite magma formed within the trachyte chamber as a result

  13. Generation and emplacement of Triassic granitoids within the Songpan Ganze accretionary-orogenic wedge in a context of slab retreat accommodated by tear faulting, Eastern Tibetan plateau, China

    NASA Astrophysics Data System (ADS)

    de Sigoyer, Julia; Vanderhaeghe, Olivier; Duchêne, Stéphanie; Billerot, Audrey

    2014-07-01

    The eastern Songpan Ganze accretionary-orogenic wedge (northern Tibetan plateau) is characterized by extensive magmatism coeval with Middle to Upper Triassic closure of the Paleotethys Ocean along a double subduction system, traced by the Kunlun-Anyemaqen suture to the north and the Jinsha-Litang suture to the south. New field, petrographic and geochemical data on Mesozoic plutons intrusive into Triassic metasediments of the eastern Songpan Ganze wedge are presented and integrated in a review of available data for the region. Three types of granitoids are distinguished: (i) high-K calc-alkaline granite to granodiorite (Yanggon, Maoergai, Markam, Sheng Meng, Xue Sheng, Taiyanghe, Menggu, Manai, Dusong Xian, Tagong and Jiulong plutons), (ii) high-K alkaline granite (Nyanbaoyeche and Rilong plutons and the Niuxingou shoshonitic syenite), and (iii) peraluminous S-type granite (Markam and Manai leucogranites). Elemental and isotopic signatures of these granitoids are consistent with the implication of both crustal (Yangtze craton, and Songpan Ganze metasediments) and mantle (asthenospheric mantle and metasomatised lithospheric mantle) sources. Based on (i) the ages of the plutons that are concomitant with the end of the northern and southern subductions of the Paleo-Tethys, (ii) the position of the plutons intrusive in the crustal tectonically accreted units decoupled from the downgoing plate of this double subduction system, (iii) the diversity of their petrological and geochemical signatures, we propose that magma emplaced in the Songpan Ganze accretionary-orogenic wedge were generated at the end of the Paleotethys closure in a context of slab retreat, accommodated by a tear fault along the passive margin of the South China block. Indeed, we argue that this context is the most favourable to trigger synchronous partial melting of (i) the suprasubduction enriched mantle wedge owing to lowering of the mantle solidus by metasomatism, (ii) the upwelled undepleted

  14. Jurassic metabasic rocks in the Kızılırmak accretionary complex (Kargı region, Central Pontides, Northern Turkey)

    NASA Astrophysics Data System (ADS)

    Çelik, Ömer Faruk; Chiaradia, Massimo; Marzoli, Andrea; Özkan, Mutlu; Billor, Zeki; Topuz, Gültekin

    2016-03-01

    The Kızılırmak accretionary complex near Kargı is tectonically bounded by the Jurassic and Early Cretaceous metamorphic massives of the Central Pontides. It consists mainly of serpentinite, serpentinized peridotite, gabbro, basalt, metabasite and deep-marine sedimentary rocks. The metabasites in the Kızılırmak accretionary complex are tectonically located within a serpentinite, radiolarian chert, spilitized basalt, gabbro association and commonly display a steep contact with serpentinites. Amphiboles from metabasites yielded robust 40Ar/39Ar plateau ages ranging between 159.4 ± 0.4 Ma and 163.5 ± 0.8 Ma. These are interpreted as cooling ages of the metabasites. The metabasites have 87Sr/86Sr(i) between 0.7035 and 0.7044 and 206Pb/204Pb(i) ranging between 18.18 and 18.92. The gabbros have higher 87Sr/86Sr(i) between 0.7044 and 0.7060 and 206Pb/204Pb(i) ranging between 17.98 and 18.43. Three basalt samples display 87Sr/86Sr(i) between 0.7040 and 0.7059. Their 206Pb/204Pb(i) are unrealistically low (15.42 and 15.62), suggesting, most likely, Pb loss which results in over-corrected values for decay through time. Pb-Sr-Nd isotopic compositions for all samples consistently plot between the fields of MORB or the Depleted MORB Mantle reservoirs and enriched mantle reservoirs (EMII rather than EMI). All the samples (except one dolerite dike) have negative ɛNdDM(t = 160 Ma) values, suggesting derivation from a reservoir more enriched than the depleted mantle. The protoliths of metabasites correspond to diverse sources (N-MORB, E-MORB, OIB and IAT) based on whole rock major and trace element composition. An IAT-like protolith for the metabasites indicates that the İzmir-Ankara-Erzincan ocean domain was subducting and the tectonic regime was compressional during Late Jurassic and before. The protoliths of these rocks were metamorphosed during the subduction/accretion processes, as observed in the metamorphic rocks located along the Balkan, Northern Turkey and

  15. Tectonic and Sedimentary Interactions on the Initiation and the Architecture of the Accretionary Wedges in the Southwestern Edge of the Caribbean, off Panama and Colombia

    NASA Astrophysics Data System (ADS)

    Mercier De Lepinay, B. F.; Maurin, T.; Barat, F.; Auxietre, J.

    2013-12-01

    The structurally and stratigraphically complex area of North Panama deformed belt, Sinu-Uraba accretionary prism and south Caribbean deformed belt holds the key to understand the plate tectonic evolution of the southwestern margins of the Caribbean Sea. New geological fieldworks, sedimentary and structural analysis, detailed offshore and onshore seismic interpretation provide insights into the regional structural and stratigraphic evolution of those margins. Detailed results constraint the geodynamic history of these complex wedge architecture which registered successive changes of sedimentary supplies and gravity collapses. During the Paleocene and Eocene time, the southeastward subduction of the Caribbean plate below the northwestern edge of South America is characterized by the development of an accretionary wedge off the Caribbean margin of Colombia, due to the accumulation of a large amount of sediments provided by the Magdalena and the Sinu rivers. The Atrato river, at that time, was providing sediments to the basins restricted within the Panama Isthmus. During the Middle Miocene, the Panama Isthmus began to collide against South America, inducing the uplift of the San Jacinto/Sinu Belt in Colombia. As a consequence, the Magdalena river was deviated northward. The Sinu river was also deviated to the North and started to load the back of the the Sinu accretionary wedge which then began to collapse as convergence has ceased. In the same way, the uplift of the Darien Shear Zone, east of the Atrato basin, has deflected the sedimentary supply from the Chucunaque/Tuira basins to the northern margin of the isthmus, allowing the development of a sedimentary basin and the initiation of the North Panama Deformed Belt. Thus, on one hand, the structure of the Colombian Wedge, the Sinu Wedge and the North Panama Deformed belt, was controlled by the tectonic forces, a consequence of the convergence and progressive accretion of the Central American isthmus against the

  16. Evaluation of Coseismic Fluid-Rock Interaction in Fault Zones on the Basis of Geochemistry of Fault Rocks in Accretionary Prisms

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Hirono, T.; Honda, G.

    2011-12-01

    Recent studies revealed that concentration and isotopic composition of fluid-mobile trace elements such as Li, Rb, Cs and Sr in slip-zone rocks can change significantly during coseismic fluid-rock interaction at high temperatures (e.g., Ishikawa et al., 2008). In this study, we summarize the results obtained for fault-zone rocks recovered from various depths of the subduction zones. Analysis of a slip-zone sample recovered from shallow portion (0.27 km bsf) of the magasplay fault at Site C0004, IODP Exp. 316, Nankai Trough showed no clear fluid-induced geochemical signals, although a peak temperature over 300 deg. C is estimated on the basis of vitrinite reflectance data (Sakaguchi et al., 2011). In contrast, a major reverse fault in a fossil accretionary prism, the Emi Group (burial depth, 1-2 km) exhibited marked decreases of Li, Rb and Cs relative to adjacent host rocks, suggesting coseismic fluid-rock interactions at >350 deg. C. Geochemical signals observed in the Emi slip zone have a strong resemblance to those observed in the Taiwan chelungpu fault at comparable depths (1.1-1.2 km). Slip-zone samples collected from a fossil out-of-sequence thrust at greater depth (2.5-5.5 km) adjacent to the Kure Melange in the Shimanto accretionary prism showed unique geochemical characteristics, in which effects from disequilibrium flash melting to generate pseudotachylyte coexist with those from fluid-rock interactions at >350 deg. C. In the cases of Emi and Chelungpu, it is possible that the fluid-induced geochemical signatures, together with fluidization structures observed in these samples, resulted from thermal pressurization. On the other hand, the Kure data suggest a slip process in which high-temperature pore fluids were generated by frictional slip, but the thermally-enhanced pressure might not have reached a sufficient level to cause thermal pressurization, and the temperature continued to increase to attain melting. Kinetic estimation suggests that fluid

  17. Formation of ophiolite-bearing tectono-sedimentary mélanges in accretionary wedges by gravity driven submarine erosion: Insights from analogue models and case studies

    NASA Astrophysics Data System (ADS)

    Malavieille, Jacques; Molli, Giancarlo; Genti, Manon; Dominguez, Stephane; Beyssac, Olivier; Taboada, Alfredo; Vitale-Brovarone, Alberto; Lu, Chia-Yu; Chen, Chih-Tung

    2016-10-01

    Orogenic wedges locally present chaotic tectonostratigraphic units that contain exotic blocks of various size, origin, age and lithology, embedded in a sedimentary matrix. The occurrence of ophiolitic blocks, sometimes huge, in such "mélanges" raises questions on (i) the mechanisms responsible for the incorporation of oceanic basement rocks into an accretionary wedge and (ii) the mechanisms allowing exhumation and redeposition of these exotic elements in "mélanges" during wedge growth. To address these questions, we present the results of a series of analogue experiments performed to characterize the processes and parameters responsible for accretion, exhumation and tectonosedimentary reworking of oceanic basement lithospheric fragments in an accretionary wedge. The experimental setup is designed to simulate the interaction between tectonics, erosion and sedimentation. Different configurations are applied to study the impact of various parameters, such as irregular oceanic floor due to structural inheritance, or the presence of layers with contrasted rheology that can affect deformation partitioning in the wedge (frontal accretion vs basal accretion) influencing its growth. Image correlation technique allows extracting instantaneous velocity field, and tracking of passive particles. By retrieving the particle paths determined from models, the pressure-temperature path of mélange units or elementary blocks can be discussed. The experimental results are then compared with observations from ophiolite-bearing mélanges in Taiwan (Lichi and Kenting mélanges) and Raman spectroscopy of carbonaceous material (RSCM) Thermometry data on rocks from the northern Apennines (Casanova mélange). A geological scenario is proposed following basic observations. The tectonic evolution of the retroside of doubly vergent accretionary wedges is mainly controlled by backthrusting and backfolding. The retro wedge is characterized by steep slopes that are prone to gravitational

  18. Tectonic and Sedimentation Interactions in the East Caribbean Subduction Zone: AN Overview from the Orinoco Delta to the Barbados Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Deville, E.

    2011-12-01

    Recent marine geophysical acquisitions and piston-coring allow to better understand the close interactions between the sand-rich Orinoco turbidite system and the compressional structures of the Barbados prism. Because of the morphologic and tectonic control in the east-Caribbean active margin, the Orinoco turbiditic pattern system does not exhibit a classic fan geometry. The sea-floor geometry between the slope of the front of the Barbados prism and the slope of the South-American margin induces the convergence of the turbidite channels toward the abyssal plain, at the front of the accretionary prism. Also, whereas in most passive margins the turbidite systems are organized upstream to downstream as canyon, then channel-levee, then lobes, here, due to the tectonic control, the sedimentary system is organized as channel-levee, then canyons, then channelized lobes. At the edge of the Orinoco platform, the system has multiple sources with several distributaries and downward the channel courses are complex with frequent convergences or divergences that are emphasized by the effects of the undulating seafloor tectonic morphologies associated with active thrust tectonics and mud volcanism. On top of the accretionary prism, turbidite sediments are filling transported piggy-back basins whose timing of sedimentation vs. deformation is complex. Erosion processes are almost absent on the highly subsiding Orinoco platform and in the upper part of the turbidite system. Erosion processes develop mostly between 2000 and 4000 m of water depth, above the compressional structures of the Barbados prism (canyons up to 3 km wide and 300 m deep). In the abyssal plain, turbiditic channels develop on very long distance (> 1000 km) joining the mid-Atlantic channel (sourced mostly by the Amazon), filling several elongated basins corresponding to transform faults (notably the Barracuda Basin), and finally sourcing the Puerto-Rico trench, the deepest morphologic depression of this region

  19. Fly ash lung: a new pneumoconiosis

    SciTech Connect

    Golden, E.B.; Warnock, M.L.; Hulett, L.D. Jr.

    1982-01-01

    A laborer who worked in a steel mill and in a shipyard developed non-specific pulmonary interstitial fibrosis. Postmortem samples of his lung were digested, and the inorganic material present was extracted and examined using transmission electron microscopy, electron diffraction, and electron microprobe analysis. Uncoated asbestos fibers were present (1.4 x 10/sup 5//g wet lung), as well as the presence of a large number of fly ash particles (6 x 10/sup 6//g wet lung). Fly ash is the particulate material produced during coal combustion. The contribution of the asbestos to this man's lung disease is uncertain. The authors believe, based on previous studies implicating aluminium silicates in pneumoconiosis, that the fly ash, an aluminium silicate, may be a contributing factor.

  20. Fly ash lung: a new pneumoconiosis

    SciTech Connect

    Golden, E.B.; Warnock, M.L.; Hulett, L.D. Jr.; Churg, A.M.

    1982-01-01

    A laborer who worked in a steel mill and in a shipyard developed a nonspecific pulmonary interstitial fibrosis. Postmortem samples of his lung were digested, and the inorganic material present was extracted and examined using transmission electron microscopy, electron diffraction, and electron microprobe analysis. Uncoated asbestos fibers were present (1.4 X 10(5)/g wet lung), but the surprising finding was the presence of a large number of fly ash particles (6 X 10(6)/g wet lung). Fly ash, the particulate material produced during coal combustion, has not previously been reported to be present in human lung tissue. Although the contribution of the asbestos to this man's lung disease is uncertain, we believe, based on previous studies implicating aluminum silicates in pneumoconiosis, that the fly ash, an aluminum silicate, may be a contributing factor.

  1. Extraction of trace metals from fly ash

    DOEpatents

    Blander, Milton; Wai, Chien M.; Nagy, Zoltan

    1984-01-01

    A process for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous, the fly ash having a silicate base and containing surface deposits of the trace metals as oxides, chlorides or the like, with the process being carried out by contacting the fly ash with AlCl.sub.3 in an alkali halide melt to react the trace metals with the AlCl.sub.3 to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

  2. Extraction of trace metals from fly ash

    DOEpatents

    Blander, M.; Wai, C.M.; Nagy, Z.

    1983-08-15

    A process is described for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous. The fly ash has a silicate base and contains surface deposits of the trace metals as oxides, chlorides or the like. The process is carried out by contacting the fly ash with AlCl/sub 3/ in an alkali halide melt to react the trace metals with the AlCl/sub 3/ to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

  3. Laboratory study of volcanic ash electrification

    NASA Astrophysics Data System (ADS)

    Alois, Stefano; Merrison, Jonathan

    2016-04-01

    Electrostatic forces play an important role in the dynamics of volcanic plumes, for example in ash dispersion and aggregation phenomena. Field measurements of ash electrification are often technically challenging due to poor access and there lacks an accepted physical theory to describe the electrical charge exchange which occurs during particle contact. The goal of the study is to investigate single particle electrification under controlled conditions using advanced laboratory facilities. A novel technique is presented, based on the use of a laser based velocimeter. Here an electric field is applied and the field-induced drift velocity of (micron-sized) ash grains is measured as well as the particles fall velocity. This allows the simultaneous determination of a suspended grains size and electrical charge. The experiments are performed in a unique environmental wind tunnel facility under controlled low-pressure conditions. Preliminary results of particle electrification will be presented.

  4. Correlation between the critical viscosity and ash fusion temperatures of coal gasifier ashes

    SciTech Connect

    Hsieh, Peter Y.; Kwong, Kyei-Sing; Bennett, James

    2015-09-27

    Coal gasification yields synthesis gas, an important intermediate in chemical manufacturing. It is also vital to the production of liquid fuels through the Fischer-Tropsch process and electricity in Integrated Gasification Combined Cycle power generation. Minerals naturally present in coal become molten in entrained-flow slagging gasifiers. Molten coal ash slag penetrates and dissolves refractory bricks, leading to costly plant shutdowns. The extent of coal ash slag penetration and refractory brick dissolution depends on the slag viscosity, the gasification temperature, and the composition of slag and bricks. Here, we measured the viscosity of several synthetic coal ash slags with a high-temperature rotary viscometer and their ash fusion temperatures through optical image analysis. We made all measurements in a carbon monoxide-carbon dioxide reducing atmosphere that approximates coal gasification conditions. Empirical correlation models based on ash fusion temperatures were used to calculate critical viscosity temperatures based on the coal ash compositions. These values were then compared with those obtained from thermodynamic phase-transition models. Finally, an understanding of slag viscosity as a function of ash composition is important to reducing refractory wear in slagging coal gasifiers, which would help to reduce the cost and environmental impact of coal for chemical and electricity production.

  5. Quantitative shape measurements of distal volcanic ash

    NASA Astrophysics Data System (ADS)

    Riley, Colleen M.; Rose, William I.; Bluth, Gregg J. S.

    2003-10-01

    Large-scale volcanic eruptions produce fine ash (<200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health. Ash particles have irregular shapes, so data on particle shape, size, and terminal velocities are needed to understand how the irregular-shaped particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize particle shapes, sizes, and terminal velocities for three ash samples of different compositions. The shape and size of 2500 particles from (1) distal fallout (˜100 km) of the 14 October 1974 Fuego eruption (basaltic), (2) the secondary maxima (˜250 km) of the 18 August 1992 Spurr eruption (andesitic), and (3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques. Samples were sorted into 10 to 19 terminal velocity groups (0.6-59.0 cm/s) using an air elutriation device. Grain-size distributions for the samples were measured using laser diffraction. Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how particle shape affects terminal velocity. These measurement values show particle shape differs greatly from a sphere (commonly used in models and algorithms). The diameters of ash particles were 10-120% larger than ideal spheres at the same terminal velocity, indicating that irregular particle shape greatly increases drag. Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that particle shapes are highly irregular. Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical particle shapes can be corrected to reflect more realistic values.

  6. Market assessment and technical feasibility study of PFBC ash use

    SciTech Connect

    Smith, V.E.; Bland, A.E.; Brown, T.H.; Georgiou, D.N.; Wheeldon, J.

    1994-10-01

    The overall objectives of this study are to determine the market potential and the technical feasibility of using PFBC ash in high volume ash use applications. The information will be of direct use to the utility industry in assessing the economics of PFBC power generation in light of ash disposal avoidance through ash marketing. In addition, the research is expected to result in the generation of generic data on the use of PFBC ash that could lead to novel processing options and procedures. The specific objectives of the proposed research and demonstration effort are: Define resent and future market potential of PFBC ash for a range of applications (Phase I); assess the technical feasibility of PFBC ash use in construction, civil engineering and agricultural applications (Phase II); and demonstrate the most promising of the market and ash use options in full-scale field demonstrations (Phase III).

  7. Ammonia absorption on coal and oil fly ashes

    SciTech Connect

    Muzio, L.J.; Kim, E.N.; McVickar, M.A.

    1996-01-01

    Ammonia and urea based post-combustion NO{sub x} control technologies (e.g., SNCR, SCR) are becoming more common as utilities strive to meet more stringent NO{sub x} emission regulations. One issue associated with these technologies is the fate of ammonia slip. A portion of the NH{sub 3} slip will be absorbed by the fly ash. Depending on the concentrations of ammonia in the ash, this may pose odor problems while handling the ash, and impact the disposal and marketability of the ash. This paper presents the results of a bench-scale study conducted to characterize NH{sub 3} absorption by fly ash. The experiment investigated NH{sub 3} absorption as a function of ash type (four coal ashes, two oil ashes), exposure time, temperature, and NH{sub 3} concentration.

  8. Microscopic study of alkali-activated fly ash

    SciTech Connect

    Katz, A.

    1998-02-01

    The activation mechanism of fly ash in a basic environment was studied as a means to improve the reactivity of fly ash in blended cements. The experimental program included activation of fly ash by a strong base (NaOH) at different concentrations, temperatures, and water-to-fly ash ratios. It was found that the degree of reactivity, as shown by the compressive strength, increases with increasing concentration of the base (up to 4 mol of NaOH) and curing temperature (up to 90 C). Lowering the sodium hydroxide to fly ash ratio by lowering the water/fly ash ratio, while maintaining the solution concentration constant yielded a lower compressive strength in spite of the lower porosity, and the high concentration of the solution. These results indicate that activation of fly ash in blended cements depends not only on the pH of the activating ambiance but also on the ratio between the latter and the fly ash.

  9. Eco-friendly fly ash utilization: potential for land application

    SciTech Connect

    Malik, A.; Thapliyal, A.

    2009-07-01

    The increase in demand for power in domestic, agricultural, and industrial sectors has increased the pressure on coal combustion and aggravated the problem of fly ash generation/disposal. Consequently the research targeting effective utilization of fly ash has also gained momentum. Fly ash has proved to be an economical substitute for expensive adsorbents as well as a suitable raw material for brick manufacturing, zeolite synthesis, etc. Fly ash is a reservoir of essential minerals but is deficient in nitrogen and phosphorus. By amending fly ash with soil and/or various organic materials (sewage sludge, bioprocess materials) as well as microbial inoculants like mycorrhizae, enhanced plant growth can be realized. Based on the sound results of large scale studies, fly ash utilization has grown into prominent discipline supported by various internationally renowned organizations. This paper reviews attempts directed toward various utilization of fly ash, with an emphasis on land application of organic/microbial inoculants amended fly ash.

  10. Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer.

    PubMed

    Chindaprasirt, Prinya; Rattanasak, Ubolluk

    2010-04-01

    In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium silicate (Na(2)SiO(3)) and 10M sodium hydroxide (NaOH) solutions at mass ratio of Na(2)SiO(3)/NaOH of 1.5 and curing temperature of 65 degrees C for 48h were used for making geopolymer. X-ray diffraction (XRD), scanning electron microscopy (SEM), degree of reaction, and thermal gravimetric analysis (TGA) were performed on the geopolymer pastes. Compressive strength was also tested on geopolymer mortars. The results show that high strength geopolymer mortars of 35.0-44.0MPa can be produced using mixture of ground FBC ash and as-received PCC-fly ash. Fine FBC ash is more reactive and results in higher degree of reaction and higher strength geopolymer as compared to the use of coarser FBC ash. Grinding increases reactivity of ash by means of increasing surface area and the amount of reactive phase of the ash. In addition, the packing effect due to fine particles also contributed to increase in strength of geopolymers.

  11. Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer

    SciTech Connect

    Chindaprasirt, Prinya; Rattanasak, Ubolluk

    2010-04-15

    In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium silicate (Na{sub 2}SiO{sub 3}) and 10 M sodium hydroxide (NaOH) solutions at mass ratio of Na{sub 2}SiO{sub 3}/NaOH of 1.5 and curing temperature of 65 deg. C for 48 h were used for making geopolymer. X-ray diffraction (XRD), scanning electron microscopy (SEM), degree of reaction, and thermal gravimetric analysis (TGA) were performed on the geopolymer pastes. Compressive strength was also tested on geopolymer mortars. The results show that high strength geopolymer mortars of 35.0-44.0 MPa can be produced using mixture of ground FBC ash and as-received PCC-fly ash. Fine FBC ash is more reactive and results in higher degree of reaction and higher strength geopolymer as compared to the use of coarser FBC ash. Grinding increases reactivity of ash by means of increasing surface area and the amount of reactive phase of the ash. In addition, the packing effect due to fine particles also contributed to increase in strength of geopolymers.

  12. Fly Ash Characteristics and Carbon Sequestration Potential

    SciTech Connect

    Palumbo, Anthony V.; Amonette, James E.; Tarver, Jana R.; Fagan, Lisa A.; McNeilly, Meghan S.; Daniels, William L.

    2007-07-20

    Concerns for the effects of global warming have lead to an interest in the potential for inexpensive methods to sequester carbon dioxide (CO2). One of the proposed methods is the sequestration of carbon in soil though the growth of crops or forests.4,6 If there is an economic value placed on sequestration of carbon dioxide in soil there may be an an opportunity and funding to utilize fly ash in the reclamation of mine soils and other degraded lands. However, concerns associated with the use of fly ash must be addressed before this practice can be widely adopted. There is a vast extent of degraded lands across the world that has some degree of potential for use in carbon sequestration. Degraded lands comprise nearly 2 X 109 ha of land throughout the world.7 Although the potential is obviously smaller in the United States, there are still approximately 4 X 106 ha of degraded lands that previously resulted from mining operations14 and an additional 1.4 X 108 ha of poorly managed lands. Thus, according to Lal and others the potential is to sequester approximately 11 Pg of carbon over the next 50 years.1,10 The realization of this potential will likely be dependent on economic incentives and the use of soil amendments such as fly ash. There are many potential benefits documented for the use of fly ash as a soil amendment. For example, fly ash has been shown to increase porosity, water-holding capacity, pH, conductivity, and dissolved SO42-, CO32-, HCO3-, Cl- and basic cations, although some effects are notably decreased in high-clay soils.8,13,9 The potential is that these effects will promote increased growth of plants (either trees or grasses) and result in greater carbon accumulation in the soil than in untreated degraded soils. This paper addresses the potential for carbon sequestration in soils amended with fly ash and examines some of the issues that should be considered in planning this option. We describe retrospective studies of soil carbon accumulation on

  13. NRL Satellite Volcanic Ash Plume Monitoring

    NASA Astrophysics Data System (ADS)

    Hawkins, J.; Kuciauskas, A. P.; Richardson, K.; Solbrig, J.; Miller, S. D.; Pavolonis, M. J.; Bankert, R.; Lee, T.; Kent, J.; Tsui, T.

    2009-12-01

    The Naval Research Laboratory’s (NRL) Marine Meteorology Division (NRL-MRY) is assembling a unique suite of near real-time digital satellite products geared towards monitoring volcanic ash plumes which can create hazardous aviation conditions. Ash plume detection, areal extent, plume top height and mass loading will be extracted via automated algorithms from a combination of geostationary (GEO) and low earth orbiting (LEO) data sets that take advantage of their complimentary strengths since no one sensor has the required spectral, spatial and temporal attributes needed. This product suite would then be available to the Volcanic Ash Advisory Centers (VAAC) and other interested users via web distribution. Initially, GOES-West and the Japanese MTSAT data will be incorporated to view volcanic plumes within the north Pacific region. Although GEO sensor spectral channels are not optimized for ash detection, temporal changes over limited timeframes can assist in plume extraction, but not for those at the highest latitudes. Examples with multi-channel techniques will be highlighted via animations. LEO sensors provide a suite of spectral channels unmatched on GEO platforms and permit enhanced ash plume monitoring. NRL has exploited the Moderate Resolution Imaging Spectroradiometer (MODIS) and SeaWiFS via a “dust enhancement technique” that has demonstrated positive plume monitoring results. Multi-channel methods using the Advanced Very High Resolution Radiometer (AVHRR) will be highlighted to take advantage of the numerous NOAA LEO satellites carrying this wide swath sensor with frequent volcano overpasses at the higher latitudes. The DMSP Operational Linescan System (OLS) provides daytime visible/infrared, as well as night time visible data which has shown value in spotting ash plumes when sufficient lunar illumination is present. The following suite of products is potentially available for over twenty (20) volcano sites world-wide via our NexSat web site: http

  14. Changeing of fly ash leachability after grinding

    NASA Astrophysics Data System (ADS)

    Lakatos, J.; Szabo, R.; Racz, A.; Banhidi, O.; Mucsi, G.

    2016-04-01

    Effect of grinding on the reactivity of fly ash used for geopolymer production was tested. Extraction technique using different alkaline and acidic solutions were used for detect the change of the solubility of elements due to the physical and mechano-chemical transformation of minerals in function of grinding time. Both the extraction with alkaline and acidic solution have detected improvement in solubility in function of grinding time. The enhancement in alkaline solution was approx. 100% in case of Si and Al. The acidic medium able to dissolve the fly ash higher manner than the alkaline, therefore the effect of grinding was found less pronounced.

  15. Utilization options for fly ash, bottom ash, and slag in Eastern Europe

    SciTech Connect

    Manz, O.E.

    1995-12-01

    Since 1967, at least six ash utilization symposiums have been held in the United States, with papers presented by several European authors on the utilization of coal by-products in Eastern Europe. There is currently over 80,000 megawatts of installed coal-fired capacity available in that region. Unfortunately, of the 117,778,000 tonnes of fly ash, bottom ash, and slag produced in Eastern Europe in 1989, only 13% was utilized. This paper outlines the research and levels and kinds of coal by-product utilization taking place in Eastern Europe since the late 1960s.

  16. Growth of Larval Agrilus planipennis (Coleoptera: Buprestidae) and Fitness of Tetrastichus planipennisi (Hymenoptera: Eulophidae) in Blue Ash (Fraxinus quadrangulata) and Green Ash (F. pennsylvanica).

    PubMed

    Peterson, Donnie L; Duan, Jian J; Yaninek, J S; Ginzel, Matthew D; Sadof, Clifford S

    2015-12-01

    Emerald ash borer (Agrilus planipennis Fairmaire) is an invasive primary pest of North American ash (Fraxinus spp.) trees. Blue ash (F. quadrangulata) is less susceptible to emerald ash borer infestations in the forest than other species of North American ash. Whereas other studies have examined adult host preferences, we compared the capacity of emerald ash borer larvae reared from emerald ash borer eggs in the field and in the laboratory to survive and grow in blue ash and the more susceptible green ash (F. pennsylvanica). Emerald ash borer larval survivorship was the same on both ash species. Mortality due to wound periderm formation was only observed in living field grown trees, but was low (<4%) in both green and blue ash. No difference in larval mortality in the absence of natural enemies suggests that both green and blue ash can support the development of emerald ash borer. Larvae reared from eggs on blue ash were smaller than on green ash growing in the field and also in bolts that were infested under laboratory conditions. In a laboratory study, parasitism rates of confined Tetrastichus planipennisi were similar on emerald ash borer larvae reared in blue and green ash bolts, as were fitness measures of the parasitoid including brood size, sex ratio, and adult female size. Thus, we postulate that emerald ash borer larvae infesting blue ash could support populations of T. planipennisi and serve as a potential reservoir for this introduced natural enemy after most of the other native ash trees have been killed. PMID:26314024

  17. Growth of Larval Agrilus planipennis (Coleoptera: Buprestidae) and Fitness of Tetrastichus planipennisi (Hymenoptera: Eulophidae) in Blue Ash (Fraxinus quadrangulata) and Green Ash (F. pennsylvanica).

    PubMed

    Peterson, Donnie L; Duan, Jian J; Yaninek, J S; Ginzel, Matthew D; Sadof, Clifford S

    2015-12-01

    Emerald ash borer (Agrilus planipennis Fairmaire) is an invasive primary pest of North American ash (Fraxinus spp.) trees. Blue ash (F. quadrangulata) is less susceptible to emerald ash borer infestations in the forest than other species of North American ash. Whereas other studies have examined adult host preferences, we compared the capacity of emerald ash borer larvae reared from emerald ash borer eggs in the field and in the laboratory to survive and grow in blue ash and the more susceptible green ash (F. pennsylvanica). Emerald ash borer larval survivorship was the same on both ash species. Mortality due to wound periderm formation was only observed in living field grown trees, but was low (<4%) in both green and blue ash. No difference in larval mortality in the absence of natural enemies suggests that both green and blue ash can support the development of emerald ash borer. Larvae reared from eggs on blue ash were smaller than on green ash growing in the field and also in bolts that were infested under laboratory conditions. In a laboratory study, parasitism rates of confined Tetrastichus planipennisi were similar on emerald ash borer larvae reared in blue and green ash bolts, as were fitness measures of the parasitoid including brood size, sex ratio, and adult female size. Thus, we postulate that emerald ash borer larvae infesting blue ash could support populations of T. planipennisi and serve as a potential reservoir for this introduced natural enemy after most of the other native ash trees have been killed.

  18. The adsorption of HCl on volcanic ash

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Xochilt; Schiavi, Federica; Keppler, Hans

    2016-03-01

    Understanding the interaction between volcanic gases and ash is important to derive gas compositions from ash leachates and to constrain the environmental impact of eruptions. Volcanic HCl could potentially damage the ozone layer, but it is unclear what fraction of HCl actually reaches the stratosphere. The adsorption of HCl on volcanic ash was therefore studied from -76 to +150 °C to simulate the behavior of HCl in the dilute parts of a volcanic plume. Finely ground synthetic glasses of andesitic, dacitic, and rhyolitic composition as well as a natural obsidian from Vulcano (Italy) served as proxies for fresh natural ash. HCl adsorption is an irreversible process and appears to increase with the total alkali content of the glass. Adsorption kinetics follow a first order law with rate constants of 2.13 ṡ10-6 s-1 to 1.80 ṡ10-4 s-1 in the temperature range investigated. For dacitic composition, the temperature and pressure dependence of adsorption can be described by the equation ln ⁡ c = 1.26 + 0.27 ln ⁡ p - 715.3 / T, where c is the surface concentration of adsorbed HCl in mg/m2, T is temperature in Kelvin, and p is the partial pressure of HCl in mbar. A comparison of this model with a large data set for the composition of volcanic ash suggests that adsorption of HCl from the gas phase at relatively low temperatures can quantitatively account for the majority of the observed Cl concentrations. The model implies that adsorption of HCl on ash increases with temperature, probably because of the increasing number of accessible adsorption sites. This temperature dependence is opposite to that observed for SO2, so that HCl and SO2 are fractionated by the adsorption process and the fractionation factor changes by four orders of magnitude over a temperature range of 250 K. The assumption of equal adsorption of different species is therefore not appropriate for deriving volcanic gas compositions from analyses of adsorbates on ash. However, with the experimental

  19. Sequence stratigraphy, structural style, and age of deformation of the Malaita accretionary prism (Solomon arc-Ontong Java Plateau convergent zone)

    NASA Astrophysics Data System (ADS)

    Phinney, Eric J.; Mann, Paul; Coffin, Millard F.; Shipley, Thomas H.

    2004-10-01

    Possibilities for the fate of oceanic plateaus at subduction zones range from complete subduction of the plateau beneath the arc to complete plateau-arc accretion and resulting collisional orogenesis. Deep penetration, multi-channel seismic reflection (MCS) data from the northern flank of the Solomon Islands reveal the sequence stratigraphy, structural style, and age of deformation of an accretionary prism formed during late Neogene (5-0 Ma) convergence between the ˜33-km-thick crust of the Ontong Java oceanic plateau and the ˜15-km-thick Solomon island arc. Correlation of MCS data with the satellite-derived, free-air gravity field defines the tectonic boundaries and internal structure of the 800-km-long, 140-km-wide accretionary prism. We name this prism the "Malaita accretionary prism" or "MAP" after Malaita, the largest and best-studied island exposure of the accretionary prism in the Solomon Islands. MCS data, gravity data, and stratigraphic correlations to islands and ODP sites on the Ontong Java Plateau (OJP) reveal that the offshore MAP is composed of folded and thrust faulted sedimentary rocks and upper crystalline crust offscraped from the Solomon the subducting Ontong Java Plateau (Pacific plate) and transferred to the Solomon arc. With the exception of an upper, sequence of Quaternary? island-derived terrigenous sediments, the deformed stratigraphy of the MAP is identical to that of the incoming Ontong Java Plateau in the North Solomon trench. We divide the MAP into four distinct, folded and thrust fault-bounded structural domains interpreted to have formed by diachronous, southeast-to-northwest, and highly oblique entry of the Ontong Java Plateau into a former trench now marked by the Kia-Kaipito-Korigole (KKK) left-lateral strike-slip fault zone along the suture between the Solomon arc and the MAP. The structural style within each of the four structural domains consists of a parallel series of three to four fault propagation folds formed by the

  20. Evidence for tectonic emplacement of ultramafic and associated rocks in the pre-Silurian eugeoclinal belt of western New England- vestiges of an ancient accretionary wedge.

    USGS Publications Warehouse

    Stanley, R.S.; Roy, D.L.; Hatch, N.L.; Knapp, D.A.

    1984-01-01

    Three ultramafic and associated rocks occur in a highly faulted zone of pre-Silurian metamorphosed rocks, in which serpentinites and talc-carbonate rocks occur as slivers along faults that separate contrasting lithic assemblages. Results of detailed investigation of the map pattern, fault fabrics, lithic assemblages and metamorphism of the ultramafic belt in the Jay area of northern Vermont and comparison with its southern continuation in Massachusetts are cited as evidence supporting interpretation of the ultramafic and associated rocks as imbricated fragments of oceanic crust. Emplacement of the fragments in a stratigraphic sequence that was originally deposited along the continental margin of North America and on adjoining oceanic crust accompanied development of an accretionary wedge associated with an east-dipping subduction zone. (Preceding abstracts)-M.S.

  1. Late Paleozoic-Mesozoic tectonic evolution of SW Japan: A review - Reappraisal of the accretionary orogeny and revalidation of the collisional model

    NASA Astrophysics Data System (ADS)

    Charvet, Jacques

    2013-08-01

    This paper makes a review of the interpretations of the tectonic evolution of SW Japan during the last three decades. In the late 1970s, the dominant model was the so-called "Pacific-type orogeny", emphasizing the purported absence of nappes and the contrast with the alpine chains, and interpreting the evolution as due to a steady oceanic subduction since the Paleozoic time. In the 80s, the discovery of the actual structure made of a pile of large thrust sheets led authors to propose collisional models, involving the intermittent underthrusting of buoyant blocks like micro-continents. At the same time, the use of high-resolution biostratigraphy allowed several authors to recognize ancient accretionary wedges, with a reconstructed ocean plate stratigraphy of individual accreted units, especially in the Tanba and Shimanto zones. Also, precise radiometric dating permitted the distinction of metamorphosed units, especially in Sanbagawa and Shimanto belts. As a result of these new data, since the 1990s, the plate tectonic interpretation of the history of the Japanese Islands was revised by Japanese scientists and presented again in terms of accretionary processes linked to a steadily oceanic subduction, with an episodic ridge subduction: the so-called "Miyashiro-type orogeny". The review of different data leads to the following conclusions. The structure of SW Japan is made of a pile of sub-horizontal nappes, polydeformed, with a geometry similar to the one encountered in collisional orogens. The geodynamic mechanisms advocated for the tectonic building within the accretionary orogeny concept (Miyashiro-type orogeny) are inappropriate. A permanent oceanic subduction with the intermittent "collision" (actually subduction) of an active ridge or seamount chain is unable to build such structures, as this process induces in fact an acceleration of the tectonic erosion and collapse of the upper plate; the underthrusting of a micro-continent or mature arc is likely needed. The

  2. Need of advanced technologies for coal ash utilization programs

    SciTech Connect

    Dube, S.K.

    1997-09-01

    National Thermal Power Corporation Ltd. (NTPC) alone produces year about 17 million tonnes of coal ash every year, out of 13 coal based stations having about 12,000 MW coal based installed capacity. The coal ash utilization program in NTPC has explored the uses of ash in the areas of raising of ash dykes, structural fills, development of low lying lands, construction of road, building materials, small brick plants, PPC, etc. In taking the studies further the Center for Power Efficiency and Environmental Protection (Cenpeep) of NTPC is evaluating the scope of employing the advanced technologies in coal ash utilization to maximize its consumption and with improved productivity. To start with it is being suggested to develop the ash ponds using more economical compacting techniques to increase the life of current ash pond. The other areas include the development of suitable grout for back filling of mine without sacrificing the productivity of mine, use of fly ash and bottom ash in the road base construction work, manufacture of clay-ash and lime ash bricks using high speed brick plants and manufacture of light weight aggregates near the consumption center. There are many other areas also where ash can find its application in large volumes.

  3. ULTRAFINE ASH AEROSOLS FROM COAL COMBUSTION: CHARACTERIZATION AND HEALTH EFFECTS

    EPA Science Inventory

    Ultrafine coal fly ash particles, defined here as those with diameters less than 0.5 micrometer, typically comprise less than 1% of the total fly ash mass. These particles are formed almost exclusively through ash vaporization, nucleation, and coagulation/condensation mechanisms,...

  4. 77 FR 55895 - Permanent Closure of Cincinnati Blue Ash Airport

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... Federal Aviation Administration Permanent Closure of Cincinnati Blue Ash Airport AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of permanent closure of Cincinnati Blue Ash Airport (ISZ). SUMMARY: The... Cincinnati advising that on August 29, 2012, it was permanently closing Cincinnati Blue Ash Airport...

  5. Evaluation of Pollutant Leaching Potential of Coal Ashes for Recycling

    NASA Astrophysics Data System (ADS)

    Park, D.; Woo, N. C.; Kim, H.; Yoon, H.; Chung, D.

    2011-12-01

    By 2009, coal ashes produced from coal-based power plants in Korea have been reused as cement supplement materials; however, the rest is mostly disposed in landfills inside the plant properties. Continuous production of coal ashes and limited landfill sites require more recycles of coal ashes as base materials, specifically in constructions of roads and of huge industrial complex. Previous researches showed that coal ashes could contain various metals such as arsenic(As), chromium(Cr), lead(Pb), nickel(Ni), selenium(Se), etc. In this study, we collected four types of bottom ashes and two of fly ashes from four coal-based power plants. These ash samples were tested with distilled water through the column leaching process in oxidized conditions. The column test results were compared with those of total digestion, sequential extraction processes and TCLP. Concentrations of metals in outflows from columns are generally greater in fly ashes than in bottom ashes, specifically for As, Se, B, Sr and SO4. Only one fly ash (J2-F) shows high concentrations of arsenic and selenium in leachate. Sequential extraction results indicate that these metals are in readily soluble forms, such as adsorbed, carbonated, and reducible forms. Results of TCLP analysis indicate no potential contaminants leached from the ashes. In conclusion, recycling of coal combustion ashes could be encouraged with proper tests such as sequential and leaching experiments.

  6. Utilization of CFB fly ash for construction applications

    SciTech Connect

    Conn, R.E.; Sellakumar, K.; Bland, A.E.

    1999-07-01

    Disposal in landfills has been the most common means of handling ash in circulating fluidized bed (CFB) boiler power plants. Recently, larger CFB boilers with generating capacities up to 300 MWe are currently being planned, resulting in increased volumes and disposal cost of ash by-product. Studies have shown that CFB ashes do not pose environmental concerns that should significantly limit their potential utilization. Many uses of CFB ash are being investigated by Foster Wheeler, which can provide more cost-effective ash management. Construction applications have been identified as one of the major uses for CFB ashes. Typically, CFB ash cannot be used as a cement replacement in concrete due to its unacceptably high sulfur content. However, CFB ashes can be used for other construction applications that require less stringent specifications including soil stabilization, road base, structural fill, and synthetic aggregate. In this study, potential construction applications were identified for fly ashes from several CFB boilers firing diverse fuels such as petroleum coke, refuse derived fuel (RDF) and coal. The compressive strength of hydrated fly ashes was measured in order to screen their potential for use in various construction applications. Based on the results of this work, the effects of both ash chemistry and carbon content on utilization potential were ascertained. Actual beneficial uses of ashes evaluated in this study are also discussed.

  7. Economic analysis of emerald ash borer (Coleoptera: Buprestidae) management options.

    PubMed

    Vannatta, A R; Hauer, R H; Schuettpelz, N M

    2012-02-01

    Emerald ash borer, Agrilus planipennis (Fairmaire) (Coleoptera: Buprestidae), plays a significant role in the health and extent of management of native North American ash species in urban forests. An economic analysis of management options was performed to aid decision makers in preparing for likely future infestations. Separate ash tree population valuations were derived from the i-Tree Streets program and the Council of Tree and Landscape Appraisers (CTLA) methodology. A relative economic analysis was used to compare a control option (do-nothing approach, only removing ash trees as they die) to three distinct management options: 1) preemptive removal of all ash trees over a 5 yr period, 2) preemptive removal of all ash trees and replacement with comparable nonash trees, or 3) treating the entire population of ash trees with insecticides to minimize mortality. For each valuation and management option, an annual analysis was performed for both the remaining ash tree population and those lost to emerald ash borer. Retention of ash trees using insecticide treatments typically retained greater urban forest value, followed by doing nothing (control), which was better than preemptive removal and replacement. Preemptive removal without tree replacement, which was the least expensive management option, also provided the lowest net urban forest value over the 20-yr simulation. A "no emerald ash borer" scenario was modeled to further serve as a benchmark for each management option and provide a level of economic justification for regulatory programs aimed at slowing the movement of emerald ash borer.

  8. A seismic sequence from Northern Apennines (Italy) provides new insight on the role of fluids in the active tectonics of accretionary wedges

    NASA Astrophysics Data System (ADS)

    Calderoni, Giovanna; Di Giovambattista, Rita; Burrato, Pierfrancesco; Ventura, Guido

    2009-04-01

    We analyze a seismic sequence which occurred in 2000 along the Northern Apennines accretionary wedge (Italy). The sequence developed within the Cretaceous-Triassic limestones of the tectonic wedge, where methane-rich and oil reservoirs are stored. Ruptures mainly developed on WNW-ESE striking thrusts. The compressive stress field is consistent with that acting at regional scale in Northern Apennines. Seismic parameters indicate that fluids are involved in the seismogenic process. The amplitudes of the P and S phases and data from some stations evidence a P to S conversion within Vp/ Vs = 2.1 layer. The attenuation properties of crust show a higher attenuation zone located west of the epicentral cloud. Eight hundred aftershocks delineate a sub-vertical cloud of events between 7 and 14 km depth. The space-time evolution of the aftershocks is consistent with a diffusive spreading (diffusivity = 1.9 m 2/s) along vertically superimposed thrusts. Diffusion also controls the time evolution of the sequence. Fluid pressure is estimated to be roughly equal to the vertical, lithostatic stress. The overpressure within reservoirs develops by tectonic compaction processes. The fluids upraise along sub-vertical fractures related to the shortening of the wedge. The 2000 sequence occurred in an area that separates a thermal and deeper petroleum system from a shallower biogenic system. The divider of these systems controls the attenuation properties of the crust. The fluid-rock interaction at seismogenetic depth is related to hydrothermal processes more than to compaction. In accretionary wedges, seismicity activating superimposed thrusts may drive methane and oil upraising from the upper crust.

  9. Deformation and fluid flow of a major out-of-sequence thrust located at seismogenic depth in an accretionary complex: Nobeoka Thrust in the Shimanto Belt, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Kondo, Hideki; Kimura, Gaku; Masago, Hideki; Ohmori-Ikehara, Kotoe; Kitamura, Yujin; Ikesawa, Eisei; Sakaguchi, Arito; Yamaguchi, Asuka; Okamoto, Shin'ya

    2005-12-01

    Nobeoka Thrust in Kyushu, southwest Japan, was investigated to understand the relationship between the seismogenic out-of-sequence thrust (OST) and fluid flow in accretionary prisms. The Nobeoka Thrust is a fossilized OST, being active at seismogenic depth. The hanging wall exhibits a penetrative plastic deformation, while a brittle, cataclastic mélange-like occurrence characterizes the footwall, although both of them have same shale and sandstone-dominant protolith. Vitrinite reflectance analyses indicate that the maximum temperatures of the hanging wall and footwall are approximately 320 and 250°C, respectively. This thermal gap across the thrust corresponds to 8.6-14.4 km of displacement assuming a 28-47°C/km geothermal gradient. The brittle damage zone of the thrust is asymmetric: only 2 m for hanging wall side and 100 m for footwall. Three types of mineral veins, quartz, and carbonate are well developed, especially in the damaged footwall: the tension crack-filling vein, the fault-filling vein, and postmélange one. The first is harmonious with fabric, perpendicular to the P surface. Fluid inclusion geothermobarometry indicates the P-T of fluid in the intensively damaged zone of the footwall is ˜300°C, 230-250 MPa, higher than that from vitrinite reflectance, which suggests that hydrothermal fluid flow is associated with deformation. The same type vein in the lowest portion of the footwall-damaged zone includes a much lower P-T fluid. This difference suggests that continuous underplating caused the damaged zone to propagate downward with cooling and shallowing, which differs from faults characterized by shear localization and might be unique to aquiferous OST in accretionary complexes.

  10. Megathrust propagation and accretionary wedge development at the front of a sediment-rich subduction system, central Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Barnes, P.; Ghisetti, F.; Ellis, S. M.; Barker, D. H. N.; Henrys, F.; Henrys, S. A.

    2014-12-01

    The central Hikurangi margin imbricated wedge is characteristic of wide (>100 km), low taper (4-5°) accretionary thrust systems associated with a relatively smooth subducting plate, thick input sedimentary sequence (~4 km in the trench), moderate convergence rate (~ 40 mm/yr), and a relatively weak interplate fault. The >65 km-wide frontal part of the wedge comprises late Cenozoic accreted turbidites and the upper pelagic sequence of the subducting Hikurangi Plateau. Whilst the deeper (10-30 km) part of the subduction interface beneath land is interseismically strongly coupled (with slow slip events reported beneath the adjacent continental shelf), the style of megathrust slip beneath the outer accretionary wedge is unknown. To support numerical forward modelling of interplate rheological and frictional properties, in a related study, we use 2D seismic reflection profiles to define the geometry of the shallow portion of the interplate megathrust, frontal wedge, and a spectacular protothrust zone outboard of the stepped frontal thrust. We reconstruct the evolution of the frontal wedge and the trench-ward propagation of the megathrust fault through progressive restoration, decompaction, and back-stripping of depth-converted seismic sections, in four stages (~0.6, 1.0, 2.0, and ≥3.5 Ma old. Folding in the fault hanging wall sequences is restored by mechanisms of fault-propagation folding and trishear. Whilst protothrusts develop as conjugate arrays with up-dip and down-dip propagation, back-thrusting on major thrust faults is relatively minor. Our preliminary results indicate spatial variations in finite shortening (~15-30%) and timing of megathrust propagation, with occurrence of out-of-sequence thrusting. Megathrust propagation may have occurred earlier than suggested in previous interpretations, with the highest shortening rates in the interval ~ 1-2 Ma. Estimated shortening rate is <10 mm/yr across the outer wedge, representing ~10-30% of total convergence.

  11. In-situ stress and strength in the Nankai inner accretionary prism at Site C0002, IODP NanTroSEIZE

    NASA Astrophysics Data System (ADS)

    Kitajima, H.; Valdez, R. D.; Kitamura, M.; Sone, H.; Saffer, D. M.; Tobin, H. J.; Hirose, T.; Kuo, S. T.

    2015-12-01

    As a part of the International Ocean Discovery Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), a deep riser borehole has been drilled into the Kumano forearc basin and the underlying inner accretionary wedge at Site C0002, located ~35 km landward from the trench. One of the primary objectives of drilling the riser site was to characterize in-situ stress and pore pressure in the hanging wall above the locked plate boundary. Here, we: (1) investigate the mechanical strength and deformation behavior of prism sediment via laboratory experiments on core samples; and (2) quantify in-situ stress (Sv, Sh, and SH), and pore pressure (Pp) in the Kumano basin and the inner prism. We conducted triaxial compression experiments on core samples recovered from ~ 2200 meters below sea floor (mbsf) during IODP Expedition 348, at effective pressures (Pe) ranging from 8 and 36 MPa, and at temperatures of either 25°C or 60°C. Our preliminary results indicate that the prism (20 - 42% porosity) rocks deform brittlely at Pe < 22 MPa, but exhibit strain hardening at Pe = 36 MPa. This pressure-porosity condition for a brittle-ductile transition is consistent with previous work defining yield models for incoming sediments at the Nankai Trough (Kitajima and Saffer, 2012). Combining P-wave velocity logs and downhole measurements of leak-off pressure at Site C0002 with an empirical relationship between P-wave velocity, porosity, and effective stress, we show that the Kumano forearc basin is in a uniaxial-strain loading path, which defines a normal faulting stress regime (Sv>SH>=Sh), whereas the inner accretionary prism is in a triaxial-strain loading path that defines a strike-slip faulting regime (SH>Sv>Sh). We estimate excess pore pressure below ~2000 mbsf ranging from 0-12 MPa, corresponding to a pore pressure ratio λ* of 0 - 0.40.

  12. Effect of fly ash on Portland cement systems. Part 1: Low-calcium fly ash

    SciTech Connect

    Papadakis, V.G.

    1999-11-01

    A typical low-calcium fly ash was used as additive in mortar, replacing part of the volume either of Portland cement or aggregate. The development of the strength, heat, porosity, boundwater, and calcium hydroxide content was measured. In aggregate replacement higher strengths were observed after 14 days, whereas in cement replacement higher strengths were observed after 91 days. The final strength gain was found to be roughly proportional to the content of active silica in the concrete volume. Bound water content and porosity results showed that fly ash reacts with calcium hydroxide, binding small amounts of water. On the basis of the experimental results, a simplified scheme describing the chemical reactions of the low-calcium fly ash in hydrating cement in proposed. Using the reaction stoichiometry, quantitative expressions for the estimation of the chemical and volumetric composition of a fly ash concrete are proposed. The model expressions can be applied in mix design and concrete performance prediction.

  13. Processing of Sugarcane Bagasse ash and Reactivity of Ash-blended Cement Mortar

    NASA Astrophysics Data System (ADS)

    Ajay, Goyal; Hattori, Kunio; Ogata, Hidehiko; Ashraf, Muhammad

    Sugarcane bagasse ash (SCBA), a sugar-mill waste, has the potential of a partial cement replacement material if processed and obtained under controlled conditions. This paper discusses the reactivity of SCBA obtained by control burning of sugarcane bagasse procured from Punjab province of India. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were employed to ascertain the amorphousness and morphology of the minerals ash particles. Destructive and non-destructive tests were conducted on SCBA-blended mortar specimens. Ash-blended cement paste specimens were analyzed by XRD, thermal analysis, and SEM methods to evaluate the hydration reaction of SCBA with cement. Results showed that the SCBA processed at 600°C for 5 hours was reactive as ash-blended mortar specimens with up to 15% substitution of cement gave better strength than control specimens.

  14. Fly ash utilization in flue gas desulfurization

    SciTech Connect

    Mouche, R.J.; Lin, M.J.L.

    1989-09-26

    This patent describes a method of enhancing the release of alkalinity from an aqueous suspension of finely divided fly ash. It comprises contacting the suspension for a period of time sufficient to increase the alkalinity of the aqueous suspension with a mixture comprising stearic acid and a member selected from the group consisting of hydrocarbon mineral oil, polalkylene glycol, alkylarlpolyether alcohol, and kerosene.

  15. 1997 Arthur Ashe Jr. Sport Scholars Awards.

    ERIC Educational Resources Information Center

    Roach, Ronald

    1997-01-01

    Winners of the "Black Issues in Higher Education" Arthur Ashe Jr. 1997 athletes of the year, one male and one female, are profiled and Sport Scholars are listed for baseball, softball, basketball, fencing, archery, football, handball, soccer, field hockey, crew, swimming, gymnastics, tennis, squash, golf, volleyball, lacrosse, wrestling, water…

  16. FLY ASH RECYCLE IN DRY SCRUBBING

    EPA Science Inventory

    The paper describes the effects of fly ash recycle in dry scrubbing. (Previous workers have shown that the recycle of product solids improves the utilization of slaked lime--Ca(OH)2--for sulfur dioxide (SO2) removal by spray dryers with bag filters.) In laboratory-scale experimen...

  17. Screening technology reduces ash in spiral circuits

    SciTech Connect

    Brodzik, P.

    2007-05-15

    In 2006, the James River Coal Co. selected the Stack Sizer to remove the minus 100 mesh high ash clay fraction from the clean coal spiral product circuits at the McCoy-Elkhorn Bevins Branch prep plant and at the Blue Diamond Leatherwood prep plant in Kentucky. The Stack Sizer is a multi-deck, high-frequency vibrating screen capable of separations as fine as 75 microns when fitted with Derrick Corp.'s patented high open area urethane screen panels. Full-scale lab tests and more than 10 months of continuous production have confirmed that the Stack Sizer fitted with Derrick 100 micron urethane screen panels consistently produces a clean coal fraction that ranges from 8 to 10% ash. Currently, each five-deck Stack Sizer operating at the Bevins Branch and Leatherwood prep plants is producing approximately 33 tons per hour of clean coal containing about 9% ash. This represents a clean coal yield of about 75% and an ash reduction of about 11% from the feed slurry. 3 figs. 2 tabs.

  18. Climate change and the ash dieback crisis

    PubMed Central

    Goberville, Eric; Hautekèete, Nina-Coralie; Kirby, Richard R.; Piquot, Yves; Luczak, Christophe; Beaugrand, Grégory

    2016-01-01

    Beyond the direct influence of climate change on species distribution and phenology, indirect effects may also arise from perturbations in species interactions. Infectious diseases are strong biotic forces that can precipitate population declines and lead to biodiversity loss. It has been shown in forest ecosystems worldwide that at least 10% of trees are vulnerable to extinction and pathogens are increasingly implicated. In Europe, the emerging ash dieback disease caused by the fungus Hymenoscyphus fraxineus, commonly called Chalara fraxinea, is causing a severe mortality of common ash trees (Fraxinus excelsior); this is raising concerns for the persistence of this widespread tree, which is both a key component of forest ecosystems and economically important for timber production. Here, we show how the pathogen and climate change may interact to affect the future spatial distribution of the common ash. Using two presence-only models, seven General Circulation Models and four emission scenarios, we show that climate change, by affecting the host and the pathogen separately, may uncouple their spatial distribution to create a mismatch in species interaction and so a lowering of disease transmission. Consequently, as climate change expands the ranges of both species polewards it may alleviate the ash dieback crisis in southern and occidental regions at the same time. PMID:27739483

  19. Mutagenicity of fly ash particles in Paramecium

    SciTech Connect

    Smith-Sonneborn, J.; Palizzi, R.A.; Herr, C.; Fisher, G.L.

    1981-01-09

    Paramecium, a protozoan that ingests nonnutritive particulate matter, was used to determine the mutagenicity of fly ash. Heat treatment inactivated mutagens that require metabolic conversion to their active form but did not destroy all mutagenicity. Extraction of particles with hydrochloric acid, but not dimethyl sulfoxide, removed detectable mutagenic activity.

  20. Hydrothermal processing of new fly ash cement

    SciTech Connect

    Jiang, W.; Roy, D.M. )

    1992-04-01

    The recent Mount Pinatubo volcanic eruption in the Philippines, in which at least 268 people died, shows that volcanic eruptions can be highly destructive. The eruption shot ash and debris over the countryside; six towns near the volcano faced a high risk of devastating mudslides, and nearly 2000 U.S. service members and their families were evacuated from two nearby military bases. However, this paper reports that not all the consequences of volcanic eruptions are bad. Under hydrothermal conditions, volcanic ash can be transformed into zeolitic tuff and, eventually, into clay minerals that constitute agricultural soils. The Materials Research Laboratory (MRL) has recently used some artificial pozzolanas (fly ash) that when mixed with lime, under hydrothermal conditions, also produced a new type of cementitious material. This was categorized as a new fly ash cement. The formation of a new hydrothermally treated wood-fiber-reinforced composite has also been demonstrated. It is apparent, however, that with respect to concerns about detailed knowledge of the reactivity of calcium silicate-based materials under hydrothermal conditions, the application of the technology far outweighs the understanding of the underlying principles of reactivity. It would seem that an understanding of reactions on the molecular level is just beginning, and that work on hydrothermal reactions is still a potentially lucrative area of research.

  1. A Profile of Ashe County, North Carolina.

    ERIC Educational Resources Information Center

    Rash, James O., Jr.; And Others

    From 1950 to 1970, the shift from agriculture to industry dominated Ashe County, North Carolina, isolated on the Blue Ridge by rugged terrain and severe weather. Rural farm population declined by 2/3 but rural non-farm population tripled. Many new industries helped shift the bulk of the work force to industry. In 1950, 45% of the work force farmed…

  2. Arthur Ashe Jr. Sports Scholars Awards 2010

    ERIC Educational Resources Information Center

    Elfman, Lois; Ford, William J.

    2010-01-01

    "Diverse: Issues In Higher Education" established the Sports Scholars Awards to honor undergraduate students of color who have made achieving both academically and athletically a winning combination. Inspired by tennis legend Arthur Ashe Jr.'s commitment to education as well as his love for the game of tennis, they invite every college and…

  3. Arthur Ashe Jr. Sports Scholars Awards 2011

    ERIC Educational Resources Information Center

    Elfman, Lois; Walker, Marlon A.

    2011-01-01

    "Diverse: Issues In Higher Education" established the Sports Scholars Awards to honor undergraduate students of color who have made achieving both academically and athletically a winning combination. Inspired by tennis legend Arthur Ashe Jr.'s commitment to education as well as his love for the game of tennis, "Diverse" invites every college and…

  4. Characterizing uncertainty in the motion, future location and ash concentrations of volcanic plumes and ash clouds

    NASA Astrophysics Data System (ADS)

    Webley, P.; Patra, A. K.; Bursik, M. I.; Pitman, E. B.; Dehn, J.; Singh, T.; Singla, P.; Stefanescu, E. R.; Madankan, R.; Pouget, S.; Jones, M.; Morton, D.; Pavolonis, M. J.

    2013-12-01

    Forecasting the location and airborne concentrations of volcanic ash plumes and their dispersing clouds is complex and knowledge of the uncertainty in these forecasts is critical to assess and mitigate the hazards that could exist. We show the results from an interdisciplinary project that brings together scientists drawn from the atmospheric sciences, computer science, engineering, mathematics, and geology. The project provides a novel integration of computational and statistical modeling with a widely-used volcanic particle dispersion code, to provide quantitative measures of confidence in predictions of the motion of ash clouds caused by volcanic eruptions. We combine high performance computing and stochastic analysis, resulting in real time predictions of ash cloud motion that account for varying wind conditions and a range of model variables. We show how coupling a real-time model for ash dispersal, PUFF, with a volcanic eruption model, BENT, allows for the definition of the variability in the dispersal model inputs and hence classify the uncertainty that can then propagate for the ash cloud location and downwind concentrations. We additionally analyze the uncertainty in the numerical weather prediction forecast data used by the dispersal model by using ensemble forecasts and assess how this affects the downwind concentrations. These are all coupled together and by combining polynomical chaos quadrature with stochastic integration techniques, we provide a quantitative measure of the reliability (i.e. error) of those predictions. We show comparisons of the downwind height calculations and mass loadings with observations of ash clouds available from satellite remote sensing data. The aim is to provide a probabilistic forecast of location and ash concentration that can be generated in real-time and used by those end users in the operational ash cloud hazard assessment environment.

  5. Ash mists and brown snow: Remobilization of volcanic ash from recent Icelandic eruptions

    NASA Astrophysics Data System (ADS)

    Liu, E. J.; Cashman, K. V.; Beckett, F. M.; Witham, C. S.; Leadbetter, S. J.; Hort, M. C.; Gudmundsson, S.

    2014-08-01

    Recent eruptions in Iceland and Chile have demonstrated that volcanic ash problems persist long after an eruption. For this reason, ash dispersion models are being extended to include ash remobilization. Critical to these models is knowledge of the ash source and the particle sizes that can be mobilized under different wind and moisture conditions. Here we characterize the physical and chemical characteristics of ash deposited on new snow in Reykjavík, Iceland, following a blizzard on 6 March 2013. Morphological, textural, and compositional analyses indicate resuspension from multiple eruptive deposits, including both Grímsvötn (2011) and Eyjafjallajökull (2010) eruptions. Grain size measurements show a mode of 32-63 µm, with particles as large as 177 µm; there is little mass in the very fine fraction, ≤10 µm (PM10). We compare our observations to predictions using the Lagrangian particle dispersion model, NAME (UK Met Office). The model output is consistent with observations in that it forecasts resuspension from both Eyjafjallajökull and Grímsvötn source regions, and shows ash deposition coincident with the timing of observed deposition in Reykjavík. The modeled deposit in Reykjavík predicts, however, a substantially lower proportion of Grímsvötn ash than observed. This discrepancy has highlighted the need to reassess the assumptions used in the simulations, particularly regarding the source area and precipitation thresholds. Furthermore, we suggest that modification of ash deposits in the form of erosion, redeposition, compaction, or cementation may influence the dynamics of resuspension over time, thus influencing the ability of model simulations to accurately forecast remobilization events.

  6. Distinguishing defensive characteristics in the phloem of ash species resistant and susceptible to emerald ash borer.

    PubMed

    Cipollini, Don; Wang, Qin; Whitehill, Justin G A; Powell, Jeff R; Bonello, Pierluigi; Herms, Daniel A

    2011-05-01

    We examined the extent to which three Fraxinus cultivars and a wild population that vary in their resistance to Emerald Ash Borer (EAB) could be differentiated on the basis of a suite of constitutive chemical defense traits in phloem extracts. The EAB-resistant Manchurian ash (F. mandshurica, cv. Mancana) was characterized by having a rapid rate of wound browning, a high soluble protein concentration, low trypsin inhibitor activities, and intermediate levels of peroxidase activity and total soluble phenolic concentration. The EAB-susceptible white ash (F. americana, cv. Autumn Purple) was characterized by a slow wound browning rate and low levels of peroxidase activity and total soluble phenolic concentrations. An EAB-susceptible green ash cultivar (F. pennsylvanica, cv. Patmore) and a wild accession were similar to each other on the basis of several chemical defense traits, and were characterized by high activities of peroxidase and trypsin inhibitor, a high total soluble phenolic concentration, and an intermediate rate of wound browning. Lignin concentration and polyphenol oxidase activities did not differentiate resistant and susceptible species. Of 33 phenolic compounds separated by HPLC and meeting a minimum criterion for analysis, nine were unique to Manchurian ash, five were shared among all species, and four were found in North American ashes and not in the Manchurian ash. Principal components analysis revealed clear separations between Manchurian, white, and green ashes on the basis of all phenolics, as well as clear separations on the basis of quantities of phenolics that all species shared. Variation in some of these constitutive chemical defense traits may contribute to variation in resistance to EAB in these species.

  7. Availability of residual phosphorus from broiler litter ash and layer manure ash amended soil for Paspalum vaginatum uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been hypothesized by several scientists that poultry litter ash could be used as a slow releasing phosphorus fertilizer that will become available over time. To test this hypothesis, a greenhouse study was conducted using a broiler litter ash, layer manure ash and calcium phosphate to determ...

  8. Sorbate characteristics of fly ash. Volume I. Final report

    SciTech Connect

    Liskowitz, J.W.; Grow, J.; Sheih, M.; Trattner, R.; Kohut, J.; Zwillenberg, M.

    1983-08-01

    The objective of this investigation is to correlate the sorbate and leaching characteristics of fly ash with coal properties and monitored combustion conditions in order to design a system for the inexpensive treatment of industrial wastes and leachate from industrial landfills using mixtures of fly ash as inexpensive sorbents. Such a low-cost treatment system could also treat ash pond effluent for water reuse by powerplants as cooling tower makeup. Twelve unblended coals from 10 different mines were burned under monitored conditions in three different types of coal fired boilers in order to determine the influence of coal composition, ash fusion temperatures, boiler additives, combustion conditions and co-firing of natural gas or oil with the coal, on the leaching and sorbate characteristics of the fly ash produced. This included the determination of: (1) SiO/sub 2/, Al/sup 2/O/sub 3/, Fe/sub 2/O/sub 3/, CaO, K/sub 2/O, Na/sub 2/O, MgO, sulfur, ash fusion temperatures Ti, Cd, Sn, Ni, Pb, Mo, Cu, Cr, n, Mn, Ba and V in the coals and their respective fly ashes and bottom ashes; (2) Moessbauer spectra of a number of coals and their fly ashes; and (3) surface analysis of the fly ashes using ESCA. The leaching exhibited by the fly ashes with regard to pH, Cd, B, Sn, Ni, Pb, Mo, Cu, Cr, Mn and Fe was examined. In addition, the removal of Cd, B, Sn, Ni, Pb, Mo, Cu, Cr, Fe, As and organics by fly ash was evaluated, using from actual ash pond samples to model realistic inlet concentrations. The results show that fly ash can be used for the treatment of Cadmium, Boron, Tin, Molybdenum, Nickel, Lead, Copper, Chromium, Zinc, Manganese, Iron, Arsenic and organics in actual ash pond effluents. 18 references, 64 figures, 60 tables.

  9. Ash3d: A finite-volume, conservative numerical model for ash transport and tephra deposition

    USGS Publications Warehouse

    Schwaiger, Hans F.; Denlinger, Roger P.; Mastin, Larry G.

    2012-01-01

    We develop a transient, 3-D Eulerian model (Ash3d) to predict airborne volcanic ash concentration and tephra deposition during volcanic eruptions. This model simulates downwind advection, turbulent diffusion, and settling of ash injected into the atmosphere by a volcanic eruption column. Ash advection is calculated using time-varying pre-existing wind data and a robust, high-order, finite-volume method. Our routine is mass-conservative and uses the coordinate system of the wind data, either a Cartesian system local to the volcano or a global spherical system for the Earth. Volcanic ash is specified with an arbitrary number of grain sizes, which affects the fall velocity, distribution and duration of transport. Above the source volcano, the vertical mass distribution with elevation is calculated using a Suzuki distribution for a given plume height, eruptive volume, and eruption duration. Multiple eruptions separated in time may be included in a single simulation. We test the model using analytical solutions for transport. Comparisons of the predicted and observed ash distributions for the 18 August 1992 eruption of Mt. Spurr in Alaska demonstrate to the efficacy and efficiency of the routine.

  10. Glass-ceramic from mixtures of bottom ash and fly ash.

    PubMed

    Vu, Dinh Hieu; Wang, Kuen-Sheng; Chen, Jung-Hsing; Nam, Bui Xuan; Bac, Bui Hoang

    2012-12-01

    Along with the gradually increasing yield of the residues, appropriate management and treatment of the residues have become an urgent environmental protection problem. This work investigated the preparation of a glass-ceramic from a mixture of bottom ash and fly ash by petrurgic method. The nucleation and crystallization kinetics of the new glass-ceramic can be obtained by melting the mixture of 80% bottom ash and 20% fly ash at 950 °C, which was then cooled in the furnace for 1h. Major minerals forming in the glass-ceramics mainly are gehlenite (Ca(2)Al(2)SiO(7)) & akermanite (Ca(2)MgSiO(7)) and wollastonite (CaSiO(3)). In addition, regarding chemical/mechanical properties, the chemical resistance showing durability, and the leaching concentration of heavy metals confirmed the possibility of engineering and construction applications of the most superior glass-ceramic product. Finally, petrurgic method of a mixture of bottom ash and fly ash at 950 °C represents a simple, inexpensive, and energy saving method compared with the conventional heat treatment.

  11. Immobilization of incinerator ash in a concrete matrix

    SciTech Connect

    Simpson, R S; Charlesworth, D L

    1988-01-01

    The ashcrete process will solidfy ash generated by the consolidated Incinerator Facility (CIF) at the Savannah River Plant (SRP). The ashcrete unit produces ashcrete, a stable cement-based wasteform, by remotely adding cement and water and tumbling drums of ash. Ashcrete product homogeneity, temperature rise during setting, and compressive strength were measured and product formulations were developed for several nonradioactive dry ash types. Saturation level and wet and dry ash densities for several ash types have been measured. Preliminary mixture formulations for the anticipated ash were tested. A proof-of-principle test was performed using a mockup of the CIF ash system. Finally, mechanical modifications to prepare the unit for use with the CIF and to ensure reliable operation are being implemented. 4 refs., 5 figs., 5 tabs.

  12. Utilization of fly ash in structural and decorative ceramic products

    SciTech Connect

    Hughes, R.E.; Dreher, G.B.; Rostam-Abadi, M.; Moore, D.M.; DeMaris, P.J.

    1996-10-01

    In this research, fly ash from coal combustion is used in fired-clay products such as bricks and related fired-clay products. Our research includes: (1) plant-scale tests of firing fly ash-brick clay mixtures; (2) laboratory-scale {open_quotes}optimization{close_quotes} of firing these mixtures; and (3) preliminary evaluations of the environmental and economic costs/benefits of ceramics made with fly ash, Bricks and feed materials were tested for compliance with market specifications and for leachability of pollutants. X-ray diffraction and chemical step-dissolution were used to determine the mineralogical composition of feed materials and products. By using mineral content, improved predictions of the firing of fly ash-clay mixtures will result. Also, estimates of coal ash fusion will improve, because testing methods and melting mechanisms for ceramics and coal ash are identical. This project could convert waste fly ash into a valuable resource.

  13. Sulfur dioxide content of Mount St. Helens' ash

    NASA Astrophysics Data System (ADS)

    Weschler, C. J.

    1984-06-01

    A rapid heating (980 C)-gas chromatographic-mass spectrometric technique was developed to measure the SO2 produced from Mount St. Helens' ash collected after the May 18, 1980, eruption. The average values of evolved SO2 for ash samples from Moses Lake, Missoula, and Helena are 215, 800, and 1250 ppm, respectively. The results suggest that the SO2 is associated primarily with new magmatic material. Experiments indicate that the SO2 is not due to sulfate species scavenged from the eruption plume or to sulfur gases adsorbed on the ash. Other possible sources include reduction of sulfate salts within the ash, bubbles of SO2 trapped within the ash, or sulfur blebs contained in the ash. Approximately as much SO2 or SO2 precursors are associated with the ash as Mount St. Helens' injected into the stratosphere.

  14. Possibilities of municipal solid waste incinerator fly ash utilisation.

    PubMed

    Hartmann, Silvie; Koval, Lukáš; Škrobánková, Hana; Matýsek, Dalibor; Winter, Franz; Purgar, Amon

    2015-08-01

    Properties of the waste treatment residual fly ash generated from municipal solid waste incinerator fly ash were investigated in this study. Six different mortar blends with the addition of the municipal solid waste incinerator fly ash were evaluated. The Portland cement replacement levels of the municipal solid waste incinerator fly ash used were 25%, 30% and 50%. Both, raw and washed municipal solid waste incinerator fly ash samples were examined. According to the mineralogical composition measurements, a 22.6% increase in the pozzolanic/hydraulic properties was observed for the washed municipal solid waste incinerator fly ash sample. The maximum replacement level of 25% for the washed municipal solid waste incinerator fly ash in mortar blends was established in order to preserve the compressive strength properties. Moreover, the leaching characteristics of the crushed mortar blend was analysed in order to examine the immobilisation of its hazardous contents.

  15. Synthetic aggregates from combustion ashes using an innovative rotary kiln.

    PubMed

    Wainwright, P J; Cresswell, D J

    2001-01-01

    This paper describes the use of a number of different combustion ashes to manufacture synthetic aggregates using an innovative rotary 'Trefoil' kiln. Three types of combustion ash were used, namely: incinerated sewage sludge ash (ISSA); municipal solid waste incinerator bottom ash (MSWIBA-- referred to here as BA); and pulverised fuel ash (Pfa). The fine waste ash fractions listed above were combined with a binder to create a plastic mix that was capable of being formed into 'green pellets'. These pellets were then fired in a Trefoil kiln to sinter the ashes into hard fused aggregates that were then tested for use as a replacement for the natural coarse aggregate in concrete. Results up to 28 days showed that these synthetic aggregates were capable of producing concretes with compressive strengths ranging from 33 to 51 MPa, equivalent to between 73 and 112% of that of the control concrete made with natural aggregates.

  16. Volcanic Ash fall Impact on Vegetation, Colima 2005

    NASA Astrophysics Data System (ADS)

    Garcia, M. G.; Martin, A.; Fonseca, R.; Nieto, A.; Radillo, R.; Armienta, M.

    2007-05-01

    An ash sampling network was established arround Colima Volcano in 2005. Ash fall was sampled on the North, Northeast, East, Southeast, South, Southwest and West of the volcano. Samples were analyzed for ash components, geochemistry and leachates. Ash fall ocurred on April (12), May (10, 23), June (2, 6, 9, 10, 12, 14), July (27), September (27), October (23) and November (24). Most of the ash is made of andesitic dome-lithics but shows diferences in crystal, juvenile material and lithic content. In May, some samples contained grey and dark pumice (scoria). Texture varies from phi >4 to phi 0. Leachate concentration were low: SO4 (7.33-54.19) Cl- (2.29-4.97) and F- (0.16-0.37). During 2005, Colima Volcano's ash fall rotted some of the guava and peach fruits and had a drying effect on spearment and epazote plants. Even these small ash amounts could have hindered sugar cane and agave growth.

  17. Chemical composition in relation with biomass ash structure

    NASA Astrophysics Data System (ADS)

    Holubcik, Michal; Jandacka, Jozef

    2014-08-01

    Biomass combustion can be more complicated like combustion of fossil fuels because it is necessary to solve problems with lower ash melting temperature. It can cause a lot of problems during combustion process. Chemical composition of biomass ash has great impact on sinters and slags creation in ash because it affects structure of heated ash. In this paper was solved relation between chemical composition and structure of heated ash from three types of biomass (spruce wood, miscanthus giganteus and wheat straw). Amount of SiO2, CaO, MgO, Al2O3 and K2O was determined. Structure of heated ash was optically determined after heating to 1000 °C or 1200 °C. Results demonstrated that chemical composition has strong effect on structure and color of heated ash.

  18. Fly ash of mineral coal as ceramic tiles raw material.

    PubMed

    Zimmer, A; Bergmann, C P

    2007-01-01

    The aim of this work was to evaluate the use of mineral coal fly ash as a raw material in the production of ceramic tiles. The samples of fly ash came from Capivari de Baixo, a city situated in the Brazilian Federal State of Santa Catarina. The fly ash and the raw materials were characterized regarding their physical chemical properties, and, based on these results; batches containing fly ash and typical raw materials for ceramic tiles were prepared. The fly ash content in the batches varied between 20 and 80 wt%. Specimens were molded using a uniaxial hydraulic press and were fired. All batches containing ash up to 60 wt% present adequate properties to be classified as several kinds of products in the ISO 13006 standard () regarding its different absorption groups (pressed). The results obtained indicate that fly ash, when mixed with traditional raw materials, has the necessary requirements to be used as a raw material for production of ceramic tiles.

  19. Possibilities of municipal solid waste incinerator fly ash utilisation.

    PubMed

    Hartmann, Silvie; Koval, Lukáš; Škrobánková, Hana; Matýsek, Dalibor; Winter, Franz; Purgar, Amon

    2015-08-01

    Properties of the waste treatment residual fly ash generated from municipal solid waste incinerator fly ash were investigated in this study. Six different mortar blends with the addition of the municipal solid waste incinerator fly ash were evaluated. The Portland cement replacement levels of the municipal solid waste incinerator fly ash used were 25%, 30% and 50%. Both, raw and washed municipal solid waste incinerator fly ash samples were examined. According to the mineralogical composition measurements, a 22.6% increase in the pozzolanic/hydraulic properties was observed for the washed municipal solid waste incinerator fly ash sample. The maximum replacement level of 25% for the washed municipal solid waste incinerator fly ash in mortar blends was established in order to preserve the compressive strength properties. Moreover, the leaching characteristics of the crushed mortar blend was analysed in order to examine the immobilisation of its hazardous contents. PMID:26060198

  20. Wet surge deposits at La Fossa di Vulcano: Depositional and eruptive mechanisms

    NASA Astrophysics Data System (ADS)

    Dellino, P.; Frazzetta, G.; La Volpe, L.

    1990-10-01

    Wet surge deposits of different volcanic cycles of the recent Fossa activity at Vulcano have been measured on a bed-by-bed basis, with data recorded to millimeter detail. The wet surge layers are varicoloured with variable thickness, with the most recurrent thickness being about 1 cm. The beds consist of fine ash without internal structures. Textural features include: (a) accretionary lapilli, of maximum size of 0.5 cm, dispersed thoroughout the layer or forming continuous layers of submillimeter size; (b) vesiculated layers which represent 10% to 65% of the total deposit; vesicles have different shapes and smooth walls, varying in volume from 1% to 15-20%; (c) soft-sediment types of bedding deformation, such as gravity flowage ripples, load cast and slumps. The slope angle has not influenced either the concentration and size of the accretionary lapilli or the shape, size, and distribution of vesicles. Only the thickness of the layers decreases with distance from the vent. SEM investigations show features indicating the hydromagmatic origin of the deposits and stressing the role of the fluid phase. Noteworthy is the presence of vesiculated grains, produced by magmatic exsolution, which show chilling effects on the internal walls of the broken bubbles. Grain size analyses reveal that the layers are not graded and most of the samples have a median size finer than 50 μm. The grain size distributions are frequently polymodal, suggesting several closely timed explosions. As all the beds exhibit the same textures, grain size, and particle morphology a single mechanism can explain their deposition. The depositional unit formed at the base of the cloud through the lateral expansion on the ground of a sticky muddy medium consisting of ash and fluid. In general each layer lost its plasticity before the deposition of the next layer. The deposition occurred in a nearly continuous sequence without periods of rest long enough to permit erosional discontinuity. The eruptions are

  1. Stabilizing soft fine-grained soils with fly ash

    SciTech Connect

    Edil, T.B.; Acosta, H.A.; Benson, C.H.

    2006-03-15

    The objective of this study was to evaluate the effectiveness of self-cementing fly ashes derived from combustion of subbituminous coal at electric power plants for stabilization of soft fine-grained soils. California bearing ratio (CBR) and resilient modulus (M{sub r}) tests were conducted on mixtures prepared with seven soft fine-grained soils (six inorganic soils and one organic soil) and four fly ashes. The soils were selected to represent a relatively broad range of plasticity, with plasticity indices ranging between 15 and 38. Two of the fly ashes are high quality Class C ashes (per ASTM C 618) that are normally used in Portland cement concrete. The other ashes are off-specification ashes, meaning they do not meet the Class C or Class F criteria in ASTM C 618. Tests were conducted on soils and soil-fly ash mixtures prepared at optimum water content (a standardized condition), 7% wet of optimum water content (representative of the typical in situ condition in Wisconsin), and 9-18% wet of optimum water content (representative of a very wet in situ condition). Addition of fly ash resulted in appreciable increases in the CBR and M{sub r} of the inorganic soils. For water contents 7% wet of optimum, CBRs of the soils alone ranged between 1 and 5. Addition of 10% fly ash resulted in CBRs ranging between 8 and 17, and 18% fly ash resulted in CBRs between 15 and 31. Similarly, M{sub r} of the soil alone ranged between 3 and 15 MPa at 7% wet of optimum, whereas addition of 10% fly ash resulted in M{sub r} between 12 and 60 MPa and 18% fly ash resulted in M{sub r} between 51 and 106 MPa. In contrast, except for one fly ash, addition of fly ash generally had little effect on CBR or M{sub r} of the organic soil.

  2. Effects of nano-SiO(2) and different ash particle sizes on sludge ash-cement mortar.

    PubMed

    Lin, K L; Chang, W C; Lin, D F; Luo, H L; Tsai, M C

    2008-09-01

    The effects of nano-SiO(2) on three ash particle sizes in mortar were studied by replacing a portion of the cement with incinerated sewage sludge ash. Results indicate that the amount of water needed at standard consistency increased as more nano-SiO(2) was added. Moreover, a reduction in setting time became noticeable for smaller ash particle sizes. The compressive strength of the ash-cement mortar increased as more nano-SiO(2) was added. Additionally, with 2% nano-SiO(2) added and a cure length of 7 days, the compressive strength of the ash-cement mortar with 1 microm ash particle size was about 1.5 times better that of 75microm particle size. Further, nano-SiO(2) functioned to fill pores for ash-cement mortar with different ash particle sizes. However, the effects of this pore-filling varied with ash particle size. Higher amounts of nano-SiO(2) better influenced the ash-cement mortar with larger ash particle sizes.

  3. On the impact of additional spectral bands usage on RST-ASH performance in volcanic ash plume detected from space

    NASA Astrophysics Data System (ADS)

    Falconieri, Alfredo; Filizzola, Carolina; Marchese, Francesco; Pergola, Nicola; Tramutoli, Valerio

    2016-04-01

    RST-ASH is an algorithm developed for detecting and tracking volcanic ash clouds from space based on the Robust Satellite Technique (RST) multi-temporal approach. For the identification of ash affected areas RST-ASH uses two local variation indexes in combination. They analyse the Brightness Temperature Differences (BTD) of the signal measured at 11 μm and 12 μm and at around 3.5 and 11 μm wavelengths to detect ash in both nighttime and daytime conditions. RST-ASH was tested on Advanced Very High Resolution Radiometer (AVHRR) and on Moderate Resolution Imaging Spectroradiometer (MODIS) records and was then implemented on Spinning Enhanced Visible and Infrared Imager (SEVIRI) for studying and monitoring eruptions of different volcanoes. In this study, some experimental configurations of RST-ASH, analyzing signal also in other spectral bands (e.g. VIS, SO2) will be tested and assessed, studying recent ash plumes (e.g. Etna, Eyjafjallajökull, Grímsvötn) affecting different geographic areas. Results achieved using both polar and geostationary satellite data will be evaluated even for comparison with other state of the art methods. The work shows that when the extended spectral capabilities offered by high temporal resolution satellites are exploited an improvement of RST-ASH performance in some observational and plume conditions is achievable, making RST-ASH still more suited for identifying and monitoring ash clouds in the framework of possible operational scenarios.

  4. Estimating potential emerald ash borer (Coleoptera: Buprestidae) populations using ash inventory data.

    PubMed

    McCullough, Deborah G; Siegert, Nathan W

    2007-10-01

    Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), a phloem-feeding pest native to Asia, was identified in June 2002 as the cause of widespread ash (Fraxinus spp.), mortality in southeastern Michigan and Windsor, Ontario, Canada. Localized populations of A. planipennis have since been found across lower Michigan and in areas of Ohio, Indiana, Illinois, Maryland, and Ontario. Officials working to contain A. planipennis and managers of forestlands near A. planipennis infestations must be able to compare alternative strategies to allocate limited funds efficiently and effectively. Empirical data from a total of 148 green ash, Fraxinus pennsylvanica Marsh., and white ash, Fraxinus americana L., trees were used to develop models to estimate surface area of the trunk and branches by using tree diameter at breast height (dbh). Data collected from 71 additional F. pennsylvanica and F. americana trees killed by A. planipennis showed that on average, 88.9 +/- 4.6 beetles developed and emerged per m2 of surface area. Models were applied to ash inventory data collected at two outlier sites to estimate potential production of A. planipennis beetles at each site. Large trees of merchantable size (dbh > or = 26 cm) accounted for roughly 6% of all ash trees at the two sites, but they could have contributed 55-65% of the total A. planipennis production at both sites. In contrast, 75- 80% of the ash trees at the outlier sites were < or =13 cm dbh, but these small trees could have contributed only < or =12% of the potential A. planipennis production at both sites. Our results, in combination with inventory data, can be used by regulatory officials and resource managers to estimate potential A. planipennis production and to compare options for reducing A. planipennis density and slowing the rate of spread for any area of interest.

  5. Volatile Contents, Degassing Behaviour and Hydration of Early-erupted Rhyolitic Pyroclasts and Ashes from Vulcan Chaitén, Chile

    NASA Astrophysics Data System (ADS)

    Tuffen, H.; Riley, C. S.; Castro, J. M.

    2010-12-01

    The concentration of dissolved volatile species in silicic pyroclasts, especially that of water, can yield key information about magma degassing and fragmentation depths. However, post-eruptive hydration can be highly problematic, with meteoric water overprinting magmatic water contents, especially in fine-grained or highly porous samples that have large surface area to volume ratios. In this study we have used thermogravimetric analysis-mass spectroscopy (TGA-MS) to characterize the volatile contents and degassing behaviour of a selection of juvenile pyroclasts and ashes erupted from Chaitén volcano, Chile in May-June 2008. The advantage of the selected samples is the short delay between eruption and collection (days to weeks), meaning that post-eruptive hydration ought to be minimal. The samples analysed, which were collected from proximal fallout deposits in June 2008, include a suite of centimetric pumices and obsidian clasts of varying porosity, the <250 μm ash fraction of the matrix, and a lapilli tuff. Samples were powdered to 125-500 μm and heated at 5 °C/min to 1250 °C after an initial 12 hour purge. Additionally, aliquots of ash samples were hydrated in distilled water for up to 3 months. The results indicate that pumices and obsidian samples have a similar total volatile content (0.7-1.6 wt %), which is dominated by water. The temperature of most rapid weight loss (dTGA peak) was significantly lower in the pumices (550-700 °C) than the dense obsidians (850-1000 °C), reflecting their greater surface area for diffusive degassing. Relationships between dTGA peak temperatures and total volatile contents are therefore different for pumices and obsidians, and results plot close to the non-hydrated obsidian endmember of Denton et al. (2009). Experimentally hydrated ash had two clearly separate dTGA peaks at 184-211 °C and 517-542 °C, which represent external and magmatic water respectively. The low-temperature peak is almost completely missing from

  6. Experimental study on ash fusion characteristics of biomass.

    PubMed

    Fang, Xiang; Jia, Li

    2012-01-01

    In this study, ash fusion characteristics (AFC) of biomass red pine, corn straw, Bermuda grass and bamboo are investigated. Results of this study show that ash melting temperatures are higher when samples are ashed at 815 °C than at 600 °C, but the differences are small. The ash deformation temperatures of pine and straw are over 1100 °C, but the ash deformation temperatures of Bermuda grass and bamboo are lower than the former biomass. Also, Bermuda grass and bamboo are prone to sintering phenomenon when burning. In the thermogravimetric experiment on ash, the heating process can be divided into three stages, namely water evaporation, oxidation of organic compounds and evaporation, and reaction of inorganic components. The ash of Bermuda grass and bamboo contains more unburned organic matters because of sintering, and higher calcium content in pine ash results in a more mass loss in the third stage. The ash fusion characteristics for co-combustion of biomass with coal are investigated. It is found that the ash melting temperature firstly decreases and then increases with the content of the corn straw increase, changing as "V" shape. PMID:22154746

  7. A Quaternary volcanic ash deposit in western Missouri

    SciTech Connect

    Emerson, J.W. )

    1993-03-01

    Quaternary volcanic ash has been found in more than fifty localities in the midwest. The most widespread deposits originated from the Long Valley caldera, California; the Jemez calderas, New Mexico; or the Yellowstone caldera, Wyoming. Fission track dating has grouped the deposits into six separate ash falls ranging from 700,000--2,000,000 years old. A small volcanic ash deposit in western Missouri may be correlative with those found along the Kansas and Marais de Cygnes rivers in eastern Kansas. The ash deposit is in Northwest Bates County Missouri, exposed along a tributary to Miami Creek, four miles east of the Kansas state line. The ash layer is interbedded with alluvial terrace deposits and ranges from fifteen to thirty inches in thickness. It is inferred to have been deposited in a pond or oxbow lake. The color is white with a pale yellow tinge (Munsell 10YR 8/2). Shard examination shows that about 70% are flat bubble-wall types, about 20% have straight ridges, less than 10% are bubble-junction, and only a trace are vesicular. The closest known volcanic ash occurrence is an ash outcropping in a Kansas river terrace near DeSoto, KS, forty-five miles to the northwest. The DeSoto deposit has been identified as the .62 m.y. Lava Creek B ash from the Yellowstone caldera. A preliminary correlation of the Missouri ash with the DeSoto ash is based on similar shard morphology and color.

  8. Water quality investigation of Kingston Fossil Plant dry ash stacking

    SciTech Connect

    Bohac, C.E.

    1990-04-01

    Changing to a dry ash disposal systems at Kingston Fossil Plant (KFP) raises several water quality issues. The first is that removing the fly ash from the ash pond could alter the characteristics of the ash pond discharge to the river. The second concerns proper disposal of the runoff and possibly leachate from the dry ash stack. The third is that dry ash stacking might change the potential for groundwater contamination at the KFP. This report addresses each of these issues. The effects on the ash pond and its discharge are described first. The report is intended to provide reference material to TVA staff in preparation of environmental review documents for new ash disposal areas at Kingston. Although the investigation was directed toward analysis of dry stacking, considerations for other disposal options are also discussed. This report was reviewed in draft form under the title Assessment of Kingston Fossil Plant Dry Ash Stacking on the Ash Pond and Groundwater Quality.'' 11 refs., 3 figs., 18 tabs.

  9. Optical properties of volcanic ash: improving remote sensing observations.

    NASA Astrophysics Data System (ADS)

    Whelley, Patrick; Colarco, Peter; Aquila, Valentina; Krotkov, Nickolay; Bleacher, Jake; Garry, Brent; Young, Kelsey; Rocha Lima, Adriana; Martins, Vanderlei; Carn, Simon

    2016-04-01

    Many times each year explosive volcanic eruptions loft ash into the atmosphere. Global travel and trade rely on aircraft vulnerable to encounters with airborne ash. Volcanic ash advisory centers (VAACs) rely on dispersion forecasts and satellite data to issue timely warnings. To improve ash forecasts model developers and satellite data providers need realistic information about volcanic ash microphysical and optical properties. In anticipation of future large eruptions we can study smaller events to improve our remote sensing and modeling skills so when the next Pinatubo 1991 or larger eruption occurs, ash can confidently be tracked in a quantitative way. At distances >100km from their sources, drifting ash plumes, often above meteorological clouds, are not easily detected from conventional remote sensing platforms, save deriving their quantitative characteristics, such as mass density. Quantitative interpretation of these observations depends on a priori knowledge of the spectral optical properties of the ash in UV (>0.3μm) and TIR wavelengths (>10μm). Incorrect assumptions about the optical properties result in large errors in inferred column mass loading and size distribution, which misguide operational ash forecasts. Similarly, simulating ash properties in global climate models also requires some knowledge of optical properties to improve aerosol speciation.

  10. The leaching characteristics of selenium from coal fly ashes

    SciTech Connect

    Wang, T.; Wang, J.; Burken, J.G.; Ban, H.; Ladwig, K.

    2007-11-15

    The leaching characteristics of selenium from several bituminous and subbituminous coal fly ashes under different pH conditions were investigated using batch methods. Results indicated that pH had a significant effect on selenium leaching from bituminous coal ash. The minimum selenium leaching occurred in the pH range between 3 and 4, while the maximum selenium leaching occurred at pH 12. The release of selenium from subbituminous coal ashes was very low for the entire experimental pH range, possibly due to the high content of calcium which can form hydration or precipitation products as a sink for selenium. The adsorption results for different selenium species indicated that Se(VI) was hardly adsorbable on either bituminous coal ashes or subbitumminous coal ashes at any pH. However, Se(I) was highly adsorbed by bituminous coal ashes under acidic pH conditions and was mostly removed by subbitumminous coal ashes across the entire pH range. This result suggests that the majority of selenium released from the tested fly ashes was Se(IV). A speciation-based model was developed to simulate the adsorption of Se(IV) on bituminous coal fly ash, and the pH-independent adsorption constants of HSeO{sup 3-} and SeO{sub 3}{sup 2-} were determined. The modeling approach is useful for understanding and predicting the release process of selenium from fly ash.

  11. Application of solid ash based catalysts in heterogeneous catalysis

    SciTech Connect

    Shaobin Wang

    2008-10-01

    Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe{sub 2}O{sub 3} could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H{sub 2} production, deSOx, deNOx, hydrocarbon oxidation, and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. 107 refs., 4 figs., 2 tabs.

  12. Environmentally friendly use of non-coal ashes in Sweden.

    PubMed

    Ribbing, C

    2007-01-01

    The Swedish Thermal Engineering Research Institute (Värmeforsk) initiated an applied research program "Environmentally friendly use of non-coal ashes", in 2002. The program aims at increasing knowledge on the by-products of energy production and their application. The goal of formulating technical and environmental guidelines and assessments is a major point of the program, which is supported by about forty authorities and private organisations. The programme has been divided into four areas: recycling of ashes to forests, geotechnical applications, use in landfilling, and environmental aspects and chemistry. Among all results obtained, the following progress is shown: *Evidence for the positive effects of spreading ashes on forest growth. *A proposal for environmental guidelines on the utilisation of ashes in construction. *A handbook for using non-coal fly ashes in unpaved roads. *Technical and environmental assessments of MSWI bottom ashes in road construction. *Development of the use of ashes with municipal wastewater sludge as a cover for landfills and mine tailings. *Use of ashes from bio-fuels in concrete and replacement of cement in stoop mining. *A method to classify those by-products from combustion that have mirror entries in the EWC as a hazardous or non-hazardous compound. The Ash Programme has also made it possible to increase knowledge on ashes as valuable materials, on quality assurance and on markets for recovered materials.

  13. Application of solid ash based catalysts in heterogeneous catalysis.

    PubMed

    Wang, Shaobin

    2008-10-01

    Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe2O3 could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H2 production, deSO(x), deNO(x), hydrocarbon oxidation,and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. PMID:18939526

  14. Laboratory compaction of fly ash and fly ash with cement additions.

    PubMed

    Zabielska-Adamska, Katarzyna

    2008-03-01

    The use of power-industry wastes as a material for earthen structures depends on its compactibility. It has been confirmed that a fly ash/bottom ash mix compacted several times in Proctor's moulds are not representative. The relationship between dry density of solid particles and water content for re-used waste samples was determined. The re-compaction effect on grain-size distribution, density of solid particles, specific surface and sand equivalent of wastes was investigated. Tests were conducted on fly ash samples compacted by the Standard and Modified Proctor methods. Another aim of the paper was to investigate the influence of cement additions on the compactibility of a fly ash/bottom ash mix. Waste samples in the natural state and with different percentages of cement additions (2, 5 and 10%) were compacted by both impact compaction methods to obtain compactibility curves rhod(w). It was found that cement addition resulted in an increased rhod max value, while wopt decreased. Linear regression relationships for changes in compaction parameters after cement stabilisation are also given. PMID:17619083

  15. Sustainable use of biofuel by recycling ash to forests: treatment of biofuel ash.

    PubMed

    Mahmoudkhani, Maryam; Richards, Tobias; Theliander, Hans

    2007-06-01

    The influence of treatment techniques on leaching properties of alkaline species from biofuel ash is investigated in this paper. Ash samples from combustion of biofuels in a circulating fluidized bed and grate-firing combustion plants are studied. The samples are treated using three different treatment techniques; self-hardening, thermal treatment, and hardening bythe addition of binding materials. Nontreated and treated samples are evaluated for the leaching properties of the alkaline compounds and, furthermore, are characterized with respect to both physical and chemical characteristics. The results show the influence of treatment techniques on the physical structure and leaching characteristics of alkaline species. Results also indicate that ash samples show different behavior when treated with different methods, i.e., the influence of treatment technique on controlling the leaching properties is highly dependent on the initial chemical composition of ash. It was also found that there is an interaction between leaching of limited and easily soluble species, e.g., calcium and potassium leaching. Therefore, to control the leaching rate of alkaline species from ash, the characteristics that correlate the leaching properties of both easily and limited soluble species need to be adjusted.

  16. 2005 world of coal ash conference proceedings

    SciTech Connect

    2005-07-01

    The theme of the conference was science, applications and sustainability. Papers are presented under the following topics: aggregates; FGD; policy; SCR; chemistry; cement and concrete (including alkali and silica reaction); agriculture; chemistry - mercury; mine reclamation; new products; and environmental management. The papers from the regulation, risk and reclamation with coal combustion byproducts at mines - OSM interactive forum and the 2005 conference on unburned carbon on utility fly ash are also included. The poster papers are included as well.

  17. Eirich technology for the preparation of ashes

    SciTech Connect

    Eirich, G.

    1994-12-31

    The paper describes a mixer manufactured by Maschinenfabrik Gustav Eirich that can be used in the agglomeration of power plant ashes and residues. No matter whether the power plant burns coal, fuel oil, wood, peat, or garbage or whether the power plant plans to dispose or utilize the residue, most flowsheets will contain an agglomeration step. The paper describes some of the uses to which this mixer can be put.

  18. Manufacture of ceramic tiles from fly ash

    SciTech Connect

    Hnat, J.G.; Mathur, A.; Simpson, J.C.

    1999-08-10

    The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants. 6 figs.

  19. Manufacture of ceramic tiles from fly ash

    SciTech Connect

    Hnat, James G.; Mathur, Akshay; Simpson, James C.

    1999-01-01

    The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants.

  20. Petrology of blueschist from the Western Himalaya (Ladakh, NW India): Exploring the complex behavior of a lawsonite-bearing system in a paleo-accretionary setting

    NASA Astrophysics Data System (ADS)

    Groppo, Chiara; Rolfo, Franco; Sachan, Himanshu K.; Rai, Santosh K.

    2016-05-01

    Although the Himalaya is the archetype of collisional orogens, formed as a consequence of the closure of the Neo-Tethyan ocean separating India from Asia, high-pressure metamorphic rocks are rare. Beside few eclogites, corresponding to the metamorphosed continental Indian crust dragged below Asia or underthrusted beneath southern Tibet, blueschists occur seldom along the Yarlung-Tsangpo Suture zone, i.e. the suture marking the India-Asia collision. These blueschists, mostly interpreted as related to paleo-accretionary prisms formed in response to the subduction of the Neo-Tethyan ocean below the Asian plate, are crucial for constraining the evolution of the India-Asia convergence zone during the closure of the Neo-Tethyan Ocean. In the Western Himalaya, the best occurrence of blueschist is that of the Sapi-Shergol Ophiolitic Mélange in Ladakh. This unit is dominated by volcanoclastic sequences rich in mafic material with subordinate interbedding of metasediments, characterized by very fresh lawsonite blueschist-facies assemblages. In this paper, the lawsonite blueschist-facies metasediments have been petrologically investigated with the aims of (i) constraining the P-T evolution of the Sapi-Shergol Ophiolitic Mélange, (ii) evaluating the influence of Fe2O3 and of H2O on the stability of the high-pressure mineral assemblages, (iii) understanding the processes controlling lawsonite formation and preservation, and (iv) interpreting the P-T evolution of the Sapi-Shergol blueschists in the framework of India-Asia collision. Our results indicate that (i) the Sapi-Shergol blueschists experienced a cold subduction history along a low thermal gradient, up to peak conditions of ca. 470 °C, 19 kbar; furthermore, in order to preserve lawsonite in the studied lithologies, exhumation must have been coupled with significant cooling, i.e. the resulting P-T path is characterized by a clockwise hairpin loop along low thermal gradients (< 8-9 °C/km); (ii) the presence of ferric

  1. Fly ash as a liming material for cotton.

    PubMed

    Stevens, Gene; Dunn, David

    2004-01-01

    A field experiment was conducted to determine the effect of fly ash from a coal combustion electric power facility on soil acidity in a cotton (Gossypium hirsutum L.) field. Fresh fly ash was applied to a Bosket fine sandy loam (fine-loamy, mixed, thermic Mollic Hapludalf) soil with an initial soil pH(salt) of 4.8. The fly ash was equivalent to 42 g kg(-1) calcium carbonate with 97% passing through a 60 mesh (U.S. standard) sieve. Fly ash was applied one day before cotton planting in 1999 at 0, 3.4, 6.7, and 10.1 Mg ha(-1). No fly ash was applied in 2000. Within 60 d of fly ash application in 1999, all rates of fly ash significantly increased soil pH above 6.0. Manganese levels in cotton petioles were reduced significantly by 6.7 and 10.1 Mg ha(-1) of fly ash. Soil boron (B) and sodium (Na) concentrations were significantly increased with fly ash. In 1999, B in cotton leaves ranged from 72 to 84 mg kg(-1) in plots with fly ash applications. However, no visual symptoms of B toxicity in plants were observed. In 1999, cotton lint yield decreased on average 12 kg ha(-1) for each Mg of fly ash applied. In 2000, cotton yields were significantly greater for the residual 3.4 and 6.7 Mg fly ash ha(-1) plots than the untreated check. Due to the adverse yield effects measured in the first year following application, fly ash would not be a suitable soil amendment for cotton on this soil at this time. PMID:14964389

  2. `Snake River (SR)-type' volcanism at the Yellowstone hotspot track: distinctive products from unusual, high-temperature silicic super-eruptions

    NASA Astrophysics Data System (ADS)

    Branney, M. J.; Bonnichsen, B.; Andrews, G. D. M.; Ellis, B.; Barry, T. L.; McCurry, M.

    2008-01-01

    A new category of large-scale volcanism, here termed Snake River (SR)-type volcanism, is defined with reference to a distinctive volcanic facies association displayed by Miocene rocks in the central Snake River Plain area of southern Idaho and northern Nevada, USA. The facies association contrasts with those typical of silicic volcanism elsewhere and records unusual, voluminous and particularly environmentally devastating styles of eruption that remain poorly understood. It includes: (1) large-volume, lithic-poor rhyolitic ignimbrites with scarce pumice lapilli; (2) extensive, parallel-laminated, medium to coarse-grained ashfall deposits with large cuspate shards, crystals and a paucity of pumice lapilli; many are fused to black vitrophyre; (3) unusually extensive, large-volume rhyolite lavas; (4) unusually intense welding, rheomorphism, and widespread development of lava-like facies in the ignimbrites; (5) extensive, fines-rich ash deposits with abundant ash aggregates (pellets and accretionary lapilli); (6) the ashfall layers and ignimbrites contain abundant clasts of dense obsidian and vitrophyre; (7) a bimodal association between the rhyolitic rocks and numerous, coalescing low-profile basalt lava shields; and (8) widespread evidence of emplacement in lacustrine-alluvial environments, as revealed by intercalated lake sediments, ignimbrite peperites, rhyolitic and basaltic hyaloclastites, basalt pillow-lava deltas, rhyolitic and basaltic phreatomagmatic tuffs, alluvial sands and palaeosols. Many rhyolitic eruptions were high mass-flux, large volume and explosive (VEI 6-8), and involved H2O-poor, low-δ18O, metaluminous rhyolite magmas with unusually low viscosities, partly due to high magmatic temperatures (900-1,050°C). SR-type volcanism contrasts with silicic volcanism at many other volcanic fields, where the fall deposits are typically Plinian with pumice lapilli, the ignimbrites are low to medium grade (non-welded to eutaxitic) with abundant pumice lapilli

  3. 'Snake River (SR)-type' volcanism at the Yellowstone hotspot track: Distinctive products from unusual, high-temperature silicic super-eruptions

    USGS Publications Warehouse

    Branney, M.J.; Bonnichsen, B.; Andrews, G.D.M.; Ellis, B.; Barry, T.L.; McCurry, M.

    2008-01-01

    A new category of large-scale volcanism, here termed Snake River (SR)-type volcanism, is defined with reference to a distinctive volcanic facies association displayed by Miocene rocks in the central Snake River Plain area of southern Idaho and northern Nevada, USA. The facies association contrasts with those typical of silicic volcanism elsewhere and records unusual, voluminous and particularly environmentally devastating styles of eruption that remain poorly understood. It includes: (1) large-volume, lithic-poor rhyolitic ignimbrites with scarce pumice lapilli; (2) extensive, parallel-laminated, medium to coarse-grained ashfall deposits with large cuspate shards, crystals and a paucity of pumice lapilli; many are fused to black vitrophyre; (3) unusually extensive, large-volume rhyolite lavas; (4) unusually intense welding, rheomorphism, and widespread development of lava-like facies in the ignimbrites; (5) extensive, fines-rich ash deposits with abundant ash aggregates (pellets and accretionary lapilli); (6) the ashfall layers and ignimbrites contain abundant clasts of dense obsidian and vitrophyre; (7) a bimodal association between the rhyolitic rocks and numerous, coalescing low-profile basalt lava shields; and (8) widespread evidence of emplacement in lacustrine-alluvial environments, as revealed by intercalated lake sediments, ignimbrite peperites, rhyolitic and basaltic hyaloclastites, basalt pillow-lava deltas, rhyolitic and basaltic phreatomagmatic tuffs, alluvial sands and palaeosols. Many rhyolitic eruptions were high mass-flux, large volume and explosive (VEI 6-8), and involved H2O-poor, low-??18O, metaluminous rhyolite magmas with unusually low viscosities, partly due to high magmatic temperatures (900-1,050??C). SR-type volcanism contrasts with silicic volcanism at many other volcanic fields, where the fall deposits are typically Plinian with pumice lapilli, the ignimbrites are low to medium grade (non-welded to eutaxitic) with abundant pumice lapilli

  4. Market assessment of PFBC ash use

    SciTech Connect

    Bland, A. E.; Brown, T. H., Western Research Institute

    1998-01-01

    Pressurized fluidized bed combustion (PFBC) of coal is undergoing demonstration in the United States, as well as throughout the world. American Electric Power`s (AEP`s) bubbling PFBC 70 MWe Tidd demonstration program in Ohio and pilot-scale development at Foster Wheeler Energia Oy 10 MWth circulating PFBC at Karhula, Finland, have demonstrated the advantages of PFBC technology. Further technology development in the US is planned with the deployment of the technology at the MacIntosh Clean Coal project in Lakeland, Florida. Development of uses for solid wastes from PFBC coal-fired power systems is being actively pursued as part of the demonstration of PFBC technologies. Ashes collected from Foster Wheeler Energia Oy pilot circulating PFBC tests in Karhula, Finland, operating on (1) low sulfur subbituminous and (2) high sulfur bituminous coal; and ash from the AEP`s high-sulfur bituminous coal-fired bubbling PFBC in Brilliant, Ohio, were evaluated in laboratory and pilot-scale ash use testing at Western Research Institute (WRI).

  5. Aerodynamic characteristics of popcorn ash particles

    SciTech Connect

    Cherkaduvasala, V.; Murphy, D.W.; Ban, H.; Harrison, K.E.; Monroe, L.S.

    2007-07-01

    Popcorn ash particles are fragments of sintered coal fly ash masses that resemble popcorn in low apparent density. They can travel with the flow in the furnace and settle on key places such as catalyst surfaces. Computational fluid dynamics (CFD) models are often used in the design process to prevent the carryover and settling of these particles on catalysts. Particle size, density, and drag coefficient are the most important aerodynamic parameters needed in CFD modeling of particle flow. The objective of this study was to experimentally determine particle size, shape, apparent density, and drag characteristics for popcorn ash particles from a coal-fired power plant. Particle size and shape were characterized by digital photography in three orthogonal directions and by computer image analysis. Particle apparent density was determined by volume and mass measurements. Particle terminal velocities in three directions were measured in water and each particle was also weighed in air and in water. The experimental data were analyzed and models were developed for equivalent sphere and equivalent ellipsoid with apparent density and drag coefficient distributions. The method developed in this study can be used to characterize the aerodynamic properties of popcorn-like particles.

  6. Arsenic release from pyrite ashes: kinetic studies.

    PubMed

    Lodolo, Andrea; Antonini, Paolo; Bukovec, Peter

    2013-01-01

    Arsenic mobility in pyrite ashes was studied because of the possible effects on water systems. The batch extraction method was used to assess kinetics and extent of As release induced by contact of the material either with rainwater or groundwater. Self-established pH-Eh range of pyrite ashes/water mixtures brought both As(III) and As(V) to be present in the water phase, as neutral arsenite H3AsO3 and anionic arsenate HAsO42-, respectively. Tests in reagent water showed both rate and extent of arsenite release higher than arsenate; total As concentration ([As] = 12 µg/L) at equilibrium little exceeded its EU Maximum Concentration Level (MCL) for surface and groundwater ([As] = 10 µg/L). Tests in groundwater, instead, showed a much higher release rate and extent for arsenate than for arsenite and the chemistry of groundwater mainly influenced arsenate mobility; total As almost instantly exceeded its MCL and it was markedly higher ([As] = 31 µg/L) at equilibrium. Overall, the study has shown the environmental implications of As mobility in the pyrite ashes, also casting light on some limits of the environmental representativeness of leaching tests in reagent water.

  7. Smectite Dehydration, Membrane Filtration, and Pore-Water Freshening in Deep Ultra-Low Permeability Formations: Deep Processes in the Nankai Accretionary Wedge

    NASA Astrophysics Data System (ADS)

    Brown, K. M.; Sample, J. C.; Even, E.; Poeppe, D.; Henry, P.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

    2014-12-01

    We address the fundamental questions surrounding the nature of water and chemical transport processes deep within sedimentary basin and accretionary-wedge environments. Consolidation and permeability studies conducted to 165 MPa (~10km depth) indicate that ultra-tight clay formations (10-18 m2 to10-21 m2) can substantially modify the fluids migrating through then. Pore-water extractions conducted on smectite/illite rich core samples obtained from 1-3 km depths at IODP (NanTroSEIZE, Chikyu) deep-riser drilling Site C0002, at the elevated loads required to squeeze waters from such deeply buried sediment (stresses up to 100 MPa),resulted in anomalous patterns of sequential freshening with progressive loading. More accurate laboratory investigations (both incremental loading and Constant Rate of Strain test) revealed that such freshening initiates above 20 MPa and progresses with consolidation to become greater than 20% by effective normal load of 165 MPa. Log-log plots of stress vs. hydraulic conductivity reveal that trends remain linear to elevated stresses and total porosities as low at 14%. The implications are that stress induced smectite dehydration and/or membrane filtration effects cause remarkable changes in pore water chemistry with fluid migration through deep, tight, clay-rich formations. These changes should occur in addition to any thermally induced diagenetic and clay-dehydration effects on pore water chemistry. Work is progressing to evaluate the impact of clay composition and temperature to ascertain if purely illitic compositions show similar trends and if the mass fractionation of water and other isotopes also occurs. Such studies will ascertain if the presence of smectite is a prerequisite for freshening or if membrane filtration is a major process in earth systems containing common clay minerals. The results have major implications for interpretations of mass chemical balances, pore water profiles, and the hydrologic, geochemical, and stress state

  8. Characterizing the Inner Accretionary Prism of the Nankai Trough with 3D Seismic and Logging While Drilling at IODP Site C0002

    NASA Astrophysics Data System (ADS)

    Boston, B.; Moore, G. F.; Jurado, M. J.; Sone, H.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

    2014-12-01

    The deeper, inner parts of active accretionary prisms have been poorly studied due the lack of drilling data, low seismic image quality and typically thick overlying sediments. Our project focuses on the interior of the Nankai Trough inner accretionary prism using deep scientific drilling and a 3D seismic cube. International Ocean Discovery Program (IODP) Expedition 348 extended the existing riser hole to more than 3000 meters below seafloor (mbsf) at Site C0002. Logging while drilling (LWD) data included gamma ray, resistivity, resistivity image, and sonic logs. LWD analysis of the lower section revealed on the borehole images intense deformation characterized by steep bedding, faults and fractures. Bedding plane orientations were measured throughout, with minor gaps at heavily deformed zones disrupting the quality of the resistivity images. Bedding trends are predominantly steeply dipping (60-90°) to the NW. Interpretation of fractures and faults in the image log revealed the existence of different sets of fractures and faults and variable fracture density, remarkably high at fault zones. Gamma ray, resistivity and sonic logs indicated generally homogenous lithology interpretation along this section, consistent with the "silty-claystone" predominant lithologies described on cutting samples. Drops in sonic velocity were observed at the fault zones defined on borehole images. Seismic reflection interpretation of the deep faults in the inner prism is exceedingly difficult due to a strong seafloor multiple, high-angle bedding dips, and low frequency of the data. Structural reconstructions were employed to test whether folding of seismic horizons in the overlying forearc basin could be from an interpreted paleothrust within the inner prism. We used a trishear-based restoration to estimate fault slip on folded horizons landward of C0002. We estimate ~500 m of slip from a steeply dipping deep thrust within the last ~0.9 Ma. Folding is not found in the Kumano sediments

  9. A new method of reconstituting the P-T conditions of fluid circulation in an accretionary prism (Shimanto, Japan) from microthermometry of methane-bearing aqueous inclusions

    NASA Astrophysics Data System (ADS)

    Raimbourg, Hugues; Thiéry, Régis; Vacelet, Maxime; Ramboz, Claire; Cluzel, Nicolas; Le Trong, Emmanuel; Yamaguchi, Asuka; Kimura, Gaku

    2014-01-01

    In paleo-accretionary prisms and the shallow metamorphic domains of orogens, circulating fluids trapped in inclusions are commonly composed of a mixture of salt water and methane, producing two types of fluid inclusions: methane-bearing aqueous and methane-rich gaseous fluid inclusions. In such geological settings, where multiple stages of deformation, veining and fluid influx are prevalent, textural relationships between aqueous and gaseous inclusions are often ambiguous, preventing the microthermometric determination of fluid trapping pressure and temperature conditions. To assess the P-T conditions of deep circulating fluids from the Hyuga unit of the Shimanto paleo-accretionary prism on Kyushu, Japan, we have developed a new computational code, applicable to the H2O-CH4-NaCl system, which allows the characterization of CH4-bearing aqueous inclusions using only the temperatures of their phase transitions estimated by microthermometry: Tmi, the melting temperature of ice; Thyd, the melting temperature of gas hydrate and Th,aq, homogenization temperature. This thermodynamic modeling calculates the bulk density and composition of aqueous inclusions, as well as their P-T isochoric paths in a P-T diagram with an estimated precision of approximatively 10%. We use this computational tool to reconstruct the entrapment P-T conditions of aqueous inclusions in the Hyuga unit, and we show that these aqueous inclusions cannot be cogenetic with methane gaseous inclusions present in the same rocks. As a result, we propose that pulses of a high-pressure, methane-rich fluid transiently percolated through a rock wetted by a lower-pressure aqueous fluid. By coupling microthermometric results with petrological data, we infer that the exhumation of the Hyuga unit from the peak metamorphic conditions was nearly isothermal and ended up under a very hot geothermal gradient. In subduction or collision zones, modeling aqueous fluid inclusions in the ternary H2O-CH4-NaCl system and not

  10. The Imbert Formation of northern Hispaniola: a tectono-sedimentary record of arc-continent collision and ophiolite emplacement in the northern Caribbean subduction-accretionary prism

    NASA Astrophysics Data System (ADS)

    Escuder-Viruete, J.; Suárez-Rodríguez, Á.; Gabites, J.; Pérez-Estaún, A.

    2016-01-01

    In northern Hispaniola, the Imbert Formation (Fm) has been interpreted as an orogenic "mélange" originally deposited as trench-fill sediments, an accretionary (subduction) complex formed above a SW-dipping subduction zone, or the sedimentary result of the early oblique collision of the Caribbean plate with the Bahama Platform in the middle Eocene. However, new stratigraphical, structural, geochemical and geochronological data from northern Hispaniola indicate that the Imbert Fm constitutes a coarsening-upward stratigraphic sequence that records the transition of the sedimentation from a pre-collisional forearc to a syn-collisional basin. This basin was transported on top of the Puerto Plata ophiolitic complex slab and structurally underlying accreted units of the Rio San Juan complex, as it was emplaced onto the North America continental margin units.

    The Imbert Fm unconformably overlies different structural levels of the Caribbean subduction-accretionary prism, including a supra-subduction zone ophiolite, and consists of three laterally discontinuous units that record the exhumation of the underlying basement. The distal turbiditic lower unit includes the latest volcanic activity of the Caribbean island arc; the more proximal turbiditic intermediate unit is moderately affected by syn-sedimentary faulting; and the upper unit is a (chaotic) olistostromic unit, composed of serpentinite-rich polymictic breccias, conglomerates and sandstones, strongly deformed by syn-sedimentary faulting, slumping and sliding processes. The Imbert Fm is followed by subsidence and turbiditic deposition of the overlying El Mamey Group.

    The 40Ar / 39Ar plagioclase plateau ages obtained in gabbroic rocks from the Puerto Plata ophiolitic complex indicate its exhumation at ˜ 45-40 Ma (lower-to-middle Eocene), contemporaneously to the sedimentation of the overlying Imbert Fm. These cooling ages imply the uplift to the surface and submarine erosion of the complex to

  11. The Imbert Formation of northern Hispaniola: a tectono-sedimentary record of arc-continent collision and ophiolite emplacement in the northern Caribbean subduction-accretionary prism

    NASA Astrophysics Data System (ADS)

    Escuder-Viruete, J.; Suárez-Rodríguez, A.; Gabites, J.; Pérez-Estaún, A.

    2015-06-01

    In northern Hispaniola, the Imbert Formation (Fm) has been interpreted as an orogenic "mélange" originally deposited as trench-fill sediments, an accretionary (subduction) complex formed above a SW-dipping subduction zone, or the sedimentary result of the early oblique collision of the Caribbean plate with the Bahama Platform in the middle Eocene. However, new stratigraphical, structural, geochemical and geochronological data from northern Hispaniola indicate that the Imbert Fm constitutes a coarsening-upward stratigraphic sequence that records the transition of the sedimentation from a pre-collisional forearc to a syn-collisional piggy-back basin. This piggy-back basin was transported on top of the Puerto Plata ophiolitic complex slab and structurally underlying accreted units of the Rio San Juan complex, as it was emplaced onto the North America continental margin units. The Imbert Fm unconformably overlies different structural levels of the Caribbean subduction-accretionary prism, including a supra-subduction zone ophiolite, and consists of three laterally discontinuous units that record the exhumation of the underlying basement. The distal turbiditic lower unit includes the latest volcanic activity of the Caribbean island arc; the more proximal turbiditic intermediate unit is moderately affected by syn-sedimentary faulting; and the upper unit is a (caotic) olistostromic unit, composed of serpentinite-rich polymictic breccias, conglomerates and sandstones, strongly deformed by syn-sedimentary faulting, slumping and sliding processes. The Imbert Fm is followed by subsidence and turbiditic deposition of the overlying El Mamey Group. The 40Ar / 39Ar plagioclase plateau ages obtained in gabbroic rocks from the Puerto Plata ophiolitic complex indicate its exhumation at ∼ 45-40 Ma (lower-to-middle Eocene), contemporaneously to the sedimentation of the overlying Imbert Fm. These cooling ages imply the uplift to the surface and submarine erosion of the complex to

  12. Constraints on the age and provenance of the Chugach accretionary complex from detrital zircons in the Sitka Graywacke near Sitka, Alaska

    USGS Publications Warehouse

    Haeussler, Peter J.; Gehrels, George E.; Karl, Susan M.

    2006-01-01

    The Sitka Graywacke is the westernmost and youngest unit of the Chugach accretionary complex in southeastern Alaska. Using laser-ablation inductively coupled plasma mass spectroscopy, we obtained 492 detrital-zircon ages on seven typical samples of Sitka Graywacke turbidites, which were collected in a transect across much of the unit near Sitka, Alaska. Individual grains range in age from 66 to 1,802 m.y. The youngest peak ages on relative-probability plots of the western four samples (74, 72, 74, and 74 m.y., from west to east) are distinctly younger than the youngest peak ages of the eastern three samples (105, 103, and 97 m.y., from west to east). These youngest peak ages set maximum depositional ages for each sample. We suggest that these peak ages are not significantly older (within ~5 m.y.) than the depositional age of the Sitka Graywacke because the deposits accumulated in a trench along a convergent margin, where magmatic sources likely continuously introduced juvenile zircons. The differences in the youngest cluster of detrital-zircon ages between the eastern and western sample localities is likely due to both a change in provenance and a fault. The similarity of the youngest peak ages in the Sitka Graywacke to fossil ages in the Valdez Group, in Prince William Sound, implies that the western part of the Sitka Graywacke is correlative with the Valdez Group, as previously inferred. However, the eastern part of the Sitka Graywacke has youngest detrital-zircon ages older than fossil ages in the Valdez Group and younger than fossil ages in the McHugh Complex, which in south-central Alaska is the oldest part of the accretionary complex. The age distribution of zircons in the older, eastern sequence suggests sources along the British Columbia margin. The detrital-zircon ages in the younger, western sequence are similar to igneous ages from south-central Alaska to southern British Columbia. Right-lateral strike slip on various fault systems inboard of the Sitka

  13. The role of silica redistribution in the evolution of slip instabilities along subduction interfaces: Constraints from the Kodiak accretionary complex, Alaska

    NASA Astrophysics Data System (ADS)

    Fisher, Donald M.; Brantley, Susan L.

    2014-12-01

    Quartz veins from a subhorizontal shear zone in the Kodiak accretionary complex in southwest Alaska record cycles of cracking and sealing contemporaneous with simple shear, and analysis of the vein array in the context of silica dissolution, diffusion, and precipitation leads to the conclusion that the time needed to seal after a fracture event overlaps with the time scales associated with the recurrence of slip instabilities along active megathrusts. The central belt of the Kodiak accretionary complex is interpreted as a shear zone developed adjacent to a paleo-decollement that was active in the Late Cretaceous based on large strain magnitudes, recumbent isoclinal folds, and regional cleavage patterns that depict rotation of the steep cleavage that characterizes most of the Kodiak Formation into the horizontal fabrics of the central belt. Within this regional shear zone, crack-seal veins composed of quartz with phyllosilicate inclusion bands are spaced at less than a cm but en echelon vein arrays are spaced at 500 cm. These arrays indicate top-to-the southeast shear on southeast dipping brittle-ductile shear zones. Vein textures indicate cracking and sealing of thin veins in the matrix, but thicker veins in en echelon sets record initial cracking and sealing followed by periodic collapse of fracture porosity at a frequency that is lower than the frequency of crack-seal cycles. Silica depletion zones in the wall rock adjacent to veins indicate local transport of silica by diffusion. By combining the maximum time in which diffusion could dominate over advection with the time needed to precipitate the quartz associated with one crack-seal band, we show that a reasonable range of ΔP, or pressure difference between matrix and crack, can produce crack seal bands in less than 10 days. This time frame is less than the recurrence of earthquakes, and similar to the duration of some slow earthquakes in nature. Therefore, silica redistribution could play a role in modulating

  14. Paleozoic subduction erosion involving accretionary wedge sediments in the South Tianshan Orogen: Evidence from geochronological and geochemical studies on eclogites and their host metasediments

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Su, Wen; Gao, Jun; Li, Jilei; Jiang, Tuo; Zhang, Xi; Ge, Xiaomei

    2014-12-01

    Geochronological and geochemical data regarding eclogites and their metasedimentary host rocks exposed in two localities of the South Tianshan (U)HP-LT metamorphic belt are presented to reveal the protolith of the eclogites and the provenance of the metasediments. The rim domains of zircon grains from the eclogites contain omphacite, phengite and rutile inclusions and give a U-Pb Concordia age of 321.4 ± 2.4 Ma, representing the peak of eclogite-facies metamorphism. The core domains of zircon grains with magmatic oscillatory zoning yield a U-Pb Concordia age of 453.9 ± 9.4 Ma, suggesting a Late Ordovician age for the eclogites' protolith. Furthermore, the inherited cores of some zircon grains have apparent U-Pb ages between 609 Ma and 2305 Ma, implying the involvement of the Precambrian basement in the formation of the eclogites' protolith. The depletion of high field strength elements and the trace element ratios indicate the eclogite protolith's continental arc affinity. The zircon U-Pb age data of the high-pressure micaschists yield seven age groups ranging from 401 Ma to 3201 Ma and cluster at a pronounced peak of ~ 445 Ma. The major and trace element compositions of the micaschists overlap those of the average upper continental crust. The protolith of the micaschist seems to have formed at an accretionary wedge, which is predominantly composed of sediments derived from Ordovician-Silurian arc-type magmatic rocks and Precambrian basement rocks in an active continental margin. The basic blocks represented by the protolith of the eclogites were most likely scraped from the basement of a continental arc by basal erosion during the subduction of the South Tianshan Ocean in Late Paleozoic. At the same time, the fragments composing the micaschists' protolith are believed to have been dragged into the subduction channel by the frontal erosion of the accretionary prism. Both the basic blocks and the sediment fragments were forced into the subduction channel, mingled

  15. Subduction history of the Paleo-Pacific plate beneath the Eurasian continent: Evidence from Mesozoic igneous rocks and accretionary complex in NE Asia

    NASA Astrophysics Data System (ADS)

    Xu, W.

    2015-12-01

    Mesozoic magmatisms in NE China can be subdivided into seven stages, i.e., Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, early Early Cretaceous, late Early Cretaceous, and Late Cretaceous. Late Triassic magmatisms consist of calc-alkaline igneous rocks in the Erguna Massif, and bimodal igneous rocks in eastern margin of Eurasian continent. The former reveals southward subduction of the Mongol-Okhotsk oceanic plate, the latter reveals an extensional environment (Xu et al., 2013). Early Jurassic magmatisms are composed of calc-alkaline igneous rocks in the eastern margin of the Eurasian continent and the Erguna Massif, revealing westward subduction of the Paleo-pacific plate and southward subduction of the Mongol-Okhotsk oceanic plate (Tang et al., 2015), respectively. Middle Jurassic magmatism only occur in the Great Xing'an Range and the northern margin of the NCC, and consists of adakitic rocks that formed in crustal thickening, reflecting the closure of the Mongol-Okhotsk ocean (Li et al., 2015). Late Jurassic and early Early Cretaceous magmatisms only occur to the west of the Songliao Basin, and consist of trackyandesite and A-type of rhyolites, revealing an extensional environment related to delamination of thickened crust. The late Early Cretaceous magmatisms are widespread in NE China, and consist of calc-alkaline volcanics in eastern margin and bimodal volcanics in intracontinent, revealing westward subduction of the Paleo-pacific plate. Late Cretaceous magmatisms mainly occur to the east of the Songliao Basin, and consist of calc-alkaline volcanics in eastern margin and alkaline basalts in intracontinent (Xu et al., 2013), revealing westward subduction of the Paleo-pacific plate. The Heilongjiang complex with Early Jurassic deformation, together with Jurassic Khabarovsk complex in Russia Far East and Mino-Tamba complex in Japan, reveal Early Jurassic accretionary history. Additionally, the Raohe complex with the age of ca. 169 Ma was

  16. Ediacaran-Devonian opening and closing of the complex Iapetus Ocean and the formation of an accretionary orogen in the northern Appalachians and British Caledonides

    NASA Astrophysics Data System (ADS)

    van Staal, Cees; Zagorevski, Alexandre

    2013-04-01

    Prior to the formation of Pangea, the Northern Appalachians-British Caledonides accretionary orogen formed over ca. 150 my by piecemeal accretion of outboard terranes to a progressively growing composite Laurentian margin. The accreted material originated either in seaways and marginal basins in the peri-Gondwanan or peri-Laurentian realms and comprises micro-continental ribbons with arc supra-structure and, to a lesser extent, supra-subduction zone oceanic slivers. The preponderance of micro-continental ribbons in Iapetus necessitates detailed knowledge of the opening history in order to understand the closure. The final opening of Iapetus took place between 550 and 540 Ma following a ca. 70 my period of rifting and formation of extensive hyper-extended, non volcanic segments with adjacent seaways partially underlain by exhumed lithospheric mantle along the Laurentian margin. The conjugate margin to Laurentia likely was represented by Arequipa-Antofalla, which was left behind when Amazonia departed earlier during the Ediacaran. Subduction in Iapetus initiated at ca. 515 Ma at opposite margins, probably as a result of a major plate reorganization following the terminal amalgamation of Gondwana. Shortly thereafter Ganderia and Avalonia diachronously rifted-off Gondwana and drifted towards Laurentia, opening the Rheic Ocean in their wake. Meguma could have travelled with Avalonia or as a separate microcontinent. Closure of the main tract of the Iapetus Ocean took place during the Late Ordovician following arc-arc collision. Iapetus' main closure did not lead to widespread orogenesis; most collisional damage took place as a result of arrival of continental ribbons at the composite Laurentian margin following closure of narrow oceanic, Iapetus-related seaways or marginal basins The resultant deformation is grouped into Cambro-Ordovician Taconic-Grampian, Silurian Salinic-Scandian and Devonian Acadian orogenies; however, these orogenies are all composite and involve

  17. The in-situ production of ash in pyroclastic flows

    NASA Astrophysics Data System (ADS)

    Manga, M.; Dufek, J.; Standish, D.

    2007-12-01

    Abrasion and fragmentation of pumice clasts during the propagation of pyroclastic flows has long been recognized as a potential source for the enhanced production of volcanic ash, however its relative importance has eluded quantification (Walker, 1981). The amount of ash produced in-situ can potentially affect runout distance, deposit sorting, the volume of ash introduced in the upper atmosphere, and internal pore pressure. We conduct a series of laboratory experiments on the collisional production of ash that may occur during different regimes of pyroclastic flow transport. We further parameterize the experiments of Cagnoli and Manga (2004) to determine the rate of production of frictional ash. We find that the energy of these interactions is insufficient to create a fractal particle size distribution; rather a bimodal suite of large particles and 10-100 micron ash particles are typically produced Using these laboratory experiments we can develop a subgrid model for ash production that can be included in analytical and multiphase numerical procedures to estimate the total volume of ash produced during transport. We examine numerically a range of initial flow energies and bed slopes over which the flows propagate. To simplify the problem we consider flows starting with 1 cm pumice clasts that can be broken up into 100 micron ash. We find that for most flow conditions10-20% of the initial 1 cm clasts comminutes into ash with the percentage increasing as a function of initial flow energy. Most of the ash is produced in the high-energy regions near the flow inlet, although flow acceleration on steep slopes can produce ash far from the vent. Ash produced at the frictional base of the flow and in the collisional upper regions of the flow can be redistributed through the entirety of the flow, although frictionally produced ash accumulates preferentially near its source in the bed-load. As slope increases, the relative proportion of ash generated by friction increases

  18. Deformation of the Calabrian accretionary wedge and relative kinematics of the Calabrian and Peloritan backstops: Insights from multibeam bathymetry, high-resolution reflection and wide-angle seismics and analog modeling

    NASA Astrophysics Data System (ADS)

    Dellong, David; Gutscher, Marc-Andre; Klingelhoefer, Frauke; Graindorge, David; Kopp, Heidrun; Moretti, Milena; Marsset, Bruno; Mercier de Lepinay, Bernard; Dominguez, Stephane; Malavieille, Jacques

    2016-04-01

    Recently acquired swath bathymetric data in the Ionian Sea document in unprecedented detail the morphostructure and dynamics of the Calabrian accretionary wedge. A boundary zone between the eastern and western lobes of the accretionary wedge is examined here. Relative displacement between the Calabrian and Peloritan backstops is expected to cause dextral strike-slip deformation between the lobes. A wide-angle seismic profile was acquired in Oct. 2014 with the R/V Meteor (DIONYSUS survey) recorded by 25 Ocean-bottom seismometers (Geomar and Ifremer instruments) and 3 land-stations (INGV stations). Inversion and forward modeling of these seismic data reveal a 5-10 km deep asymmetric rift zone between the Malta Escarpment and the SW tip of Calabria. Analog modeling was performed to test if the origin of this rift could be related to the relative kinematics of the Calabrian and Peloritan backstops. Modeling, using two independently moving backstops, produces a zone of dextral transtension and subsidence in the accretionary wedge between two lobes. This corresponds well to the asymmetric rift observed in the southward prolongation of the straits of Messina faults. Paradoxically however, this dextral displacement does not appear to traverse the external Calabrian accretionary wedge, where prominent curved lineaments observed indicate a sinistral sense of motion. One possible explanation is that the dextral kinematic motion is transferred into a region of crisscrossing faults in the internal portion of the Eastern lobe. The bathymetry and high-resolution reflection seismic images indicate ongoing compression at the deformation front of both the western and eastern lobes. Together with the analog modeling results, these observations unambiguously demonstrate that the western lobe remains tectonically active.

  19. Feeding by emerald ash borer larvae induces systemic changes in black ash foliar chemistry.

    PubMed

    Chen, Yigen; Whitehill, Justin G A; Bonello, Pierluigi; Poland, Therese M

    2011-11-01

    The exotic wood-boring pest, emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has been threatening North American ash (Fraxinus spp.) resources, this being recognized since its first detection in Michigan, USA and Ontario, Canada in 2002. Ash trees are killed by larval feeding in the cambial region, which results in disruption of photosynthate and nutrient translocation. In this study, changes in volatile and non-volatile foliar phytochemicals of potted 2-yr-old black ash, Fraxinus nigra Marshall, seedlings were observed in response to EAB larval feeding in the main stem. EAB larval feeding affected levels of six compounds [hexanal, (E)-2-hexenal, (Z)-3-hexenyl acetate, (E)-β-ocimene, methyl salicylate, and (Z,E)-α-farnesene] with patterns of interaction depending upon compounds of interest and time of observation. Increased methyl salicylate emission suggests similarity in responses induced by EAB larval feeding and other phloem-feeding herbivores. Overall, EAB larval feeding suppressed (Z)-3-hexenyl acetate emission, elevated (E)-β-ocimene emission in the first 30days, but emissions leveled off thereafter, and generally increased the emission of (Z,E)-α-farnesene. Levels of carbohydrates and phenolics increased overall, while levels of proteins and most amino acids decreased in response to larval feeding. Twenty-three amino acids were consistently detected in the foliage of black ash. The three most abundant amino acids were aspartic acid, glutamic acid, glutamine, while the four least abundant were α-aminobutyric acid, β-aminoisobutyric acid, methionine, and sarcosine. Most (16) foliar free amino acids and 6 of the 9 detected essential amino acids decreased with EAB larval feeding. The ecological consequences of these dynamic phytochemical changes on herbivores harbored by ash trees and potential natural enemies of these herbivores are discussed.

  20. Compressive strength of cement stabilized fly ash-soil mixtures

    SciTech Connect

    Kaniraj, S.R.; Havanagi, V.G.

    1999-05-01

    Rajghat fly ash from Delhi, India, and Baumineral fly ash near Bochum, Germany, were mixed with the locally available soils -- silt and Yamuna sand with Rajghat fly ash and Rhine sand with Baumineral fly ash -- in different proportions. Cement, varying from 3--9%, was added to stabilize the fly ash-soil mixtures. Cylindrical samples were prepared at optimum moisture content and maximum dry density and were cured for different duration. Unconfined compression tests were conducted on these samples. Correlations for unconfined compressive strength and secant modulus as functions of curing time, fly ash content, and cement content have been established. The data were analyzed with other correlations recommended in literature and comparisons between the correlations have been made. Correlations for water content as functions of curing time and cement content have also been established.

  1. Analyses of ashes from the Tidd PFBC advanced particulate filter

    SciTech Connect

    Snyder, T.R.; Pontius, D.H.

    1995-08-01

    Early observations of the Advanced Particulate Filter (APF) at the Tidd PFBC Demonstration Plant led to the conclusion that tenacious ash deposits formed in the filter vessel and induced stresses that resulted in bent or broken ceramic candle filter elements. The proximity of these bent and broken candle filter elements to large, strong ash deposits emphasized the need to prevent or control the growth of these deposits, facilitate their on-line removal, and/or to develop filter design criteria to minimize their effects on individual filter elements. The chemical characteristics of the ashes collected in the Tidd APF combined with the environment within the filter vessel tend to cause ash deposits formed in the filter vessel to consolidate and strengthen. One theory that may explain the growth and strengthening of these deposits is based on the formation of eutectics such as various calcium aluminosilicate compounds. These eutectics form when primary coal ash particles come into physical contact with sorbent-derived ash particles which contain relatively large amounts of magnesium and/or calcium. Aluminosilicate compounds in the coal ash particles react with alkali metals in the sorbent ash particles to form eutectics that melt at relatively low temperatures. The surface tension of the near-liquid layer on the particles pulls adjacent ash particles closer together, thereby eventually consolidating the structure of the entire ash agglomerate. The optimum solution to the problems caused by the ash aggregates that have been consolidated and strengthened by pervasive eutectic formation is the removal of these aggregates from the APF before the eutectics have had enough time to develop. The approach that proved most successful in eliminating the deposits was the total bypassing of the cyclone upstream of the APF. This increased the size distribution of the particles forming the various ash deposits, thereby decreasing their inherent cohesivity.

  2. Recovery of aluminum and other metal values from fly ash

    DOEpatents

    McDowell, William J.; Seeley, Forest G.

    1981-01-01

    The invention described herein relates to a method for improving the acid leachability of aluminum and other metal values found in fly ash which comprises sintering the fly ash, prior to acid leaching, with a calcium sulfate-containing composition at a temperature at which the calcium sulfate is retained in said composition during sintering and for a time sufficient to quantitatively convert the aluminum in said fly ash into an acid-leachable form.

  3. Recovery of aluminum and other metal values from fly ash

    DOEpatents

    McDowell, W.J.; Seeley, F.G.

    1979-11-01

    The invention relates to a method for improving the acid leachability of aluminum and other metal values found in fly ash which comprises sintering the fly ash, prior to acid leaching, with a calcium sulfate-containing composition at a temperature at which the calcium sulfate is retained in said composition during sintering and for a time sufficient to quantitatively convert the aluminum in said fly ash into an acid-leachable form.

  4. Slagging and fluidity behavior of coal ash under gasifier environment

    SciTech Connect

    Kim, H.T.; Bae, H.J.; Lee, S.H.; Park, J.S.; Yun, Y.S.; Chung, S.W.

    1997-12-31

    The objective of this study is to predict the slagging and fluidity behavior of coal ashes from the physical/chemical properties of parent coals to determine the optimum operating parameter of a slagging-type coal gasifier. Three types of coal samples, such as Alaska Usibelli, China Datong and Posco (blended coal), are analyzed for their ash composition and ash fusion temperature. To investigate the effect of flux addition on ash slagging behavior, optimum quantity of CaO addition is evaluated with considering negative effect of CaO addition on gasification reaction. The effect of blending of Posco coal with Alaska and Datong coal on ash slagging is also investigated to expand the variety and performance of coal types in slagging-type entrained-bed gasifier. The results of the experiment shows that the optimum CaO fluxing quantity is 10%, 20% on Alaska and Dating coal, respectively. However, optimum blending ratio for ash slagging is not found when mixing Posco coal with Alaska or Datong coals. Melting and slagging characteristics of coal ash samples with changing temperature are examined in detail by DTA. ASTM ash melting temperatures as well as critical viscosity temperature are compared with TGA and DTA profiles. DTA experiments illustrate that coal ash starts to melt before the IDT (initial deformation temperature) and that theoretical T{sub CV} is well correlated with DTA profile. Experiment of ash fluidity are also carried on with the Alaska and Datong coal ashes using a high temperature viscometer. The experimental viscosity data is compared with the calculated viscosity and results show good correlation. As a result, viscosity of coal ash could be calculated with the Watt and Fereday equation in the high temperature range. The experimental results from this investigation will be used as reference data for determining optimum operating condition of 3t/d bench scale unit gasifier which is located in Ajou University, Suwon, Korea.

  5. Improved prediction and tracking of volcanic ash clouds

    USGS Publications Warehouse

    Webley, P.; Mastin, L.

    2009-01-01

    During the past 30??years, more than 100 airplanes have inadvertently flown through clouds of volcanic ash from erupting volcanoes. Such encounters have caused millions of dollars in damage to the aircraft and have endangered the lives of tens of thousands of passengers. In a few severe cases, total engine failure resulted when ash was ingested into turbines and coating turbine blades. These incidents have prompted the establishment of cooperative efforts by the International Civil Aviation Organization and the volcanological community to provide rapid notification of eruptive activity, and to monitor and forecast the trajectories of ash clouds so that they can be avoided by air traffic. Ash-cloud properties such as plume height, ash concentration, and three-dimensional ash distribution have been monitored through non-conventional remote sensing techniques that are under active development. Forecasting the trajectories of ash clouds has required the development of volcanic ash transport and dispersion models that can calculate the path of an ash cloud over the scale of a continent or a hemisphere. Volcanological inputs to these models, such as plume height, mass eruption rate, eruption duration, ash distribution with altitude, and grain-size distribution, must be assigned in real time during an event, often with limited observations. Databases and protocols are currently being developed that allow for rapid assignment of such source parameters. In this paper, we summarize how an interdisciplinary working group on eruption source parameters has been instigating research to improve upon the current understanding of volcanic ash cloud characterization and predictions. Improved predictions of ash cloud movement and air fall will aid in making better hazard assessments for aviation and for public health and air quality. ?? 2008 Elsevier B.V.

  6. Market opportunities for fly ash fillers in North America

    SciTech Connect

    Eckert, C.; Harris, T.; Gledhill, J. )

    1990-11-01

    Direct Acid Leaching (DAL) processed fly ash is derived from treating raw and beneficiated coal fly ash with hydrochloric acid. The DAL process allows for the production of fly ash with greater chemical purity and consistency than raw fly ash alone. In addition, DAL fly ash is similar to various minerals used in a wide range of applications that require filler minerals. This project investigates the feasibility of using three grades of DAL fly ash ranging from 10 microns to 30 microns in diameter as an alternative filler material to mineral fillers. Six major applications in North America, requiring large volumes of filler minerals were investigated by region including: (1) asphalt roofing shingles (2) carpet backing (3) joint compound and wallboard (4) industrial coatings (5) plastics (6) vinyl flooring. It is determined that calcium carbonate was the primary mineral filler DAL fly ash would be competing with in the applications investigated. Calcium carbonate is used in all applications investigated. The application which demonstrated the greatest potential for using DAL fly ash is asphalt shingles. Asphalt shingles were the largest calcium carbonate consuming application identified, consuming 4.8 million tons in 1988, and is the least sensitive to the dark color of the DAL fly ash. Although the DAL fly ash typically has a smaller particle size, in comparison to calcium carbonate, the asphalt shingle manufacturers felt it would be a good substitute. Other promising applications for DAL fly ash were industrial coatings and plastics where the calcium carbonate particle size requirements of 3 to 6 microns very closely matches the particle size of the DAL fly ash considered in this project. 17 figs., 36 tabs.

  7. Strength enhancement of concrete containing MSW incinerator ash

    SciTech Connect

    Cobb, J.T. Jr.; Lewis, J.T. II

    1995-12-31

    In previous work pretreatment of fresh municipal solid waste incinerator ash with an alkalinity reduction agent was shown to markedly increase the compressive strength of portland cement concrete using the ash as fine aggregate. Recent studies have shown that aged ash does not demonstrate the same enhancement. This presentation will review the previous study, give the results of the current one and discuss the implications.

  8. Ash content of bones in the pigtail monkey, Macaca nemestrina.

    NASA Technical Reports Server (NTRS)

    Vose, G. P.; Roach, T. L.

    1972-01-01

    Ash analyses of skeletons of four adult primates, Macaca nemestrina, revealed some similarities and some marked contrasts when compared with published data on human skeletal ash. The skull in both Macaca nemestrina and man has the highest ash content of all bones in the skeleton. While the bones of the arms of humans have an ash content nearly identical to that of the legs (0.3% difference), in Macaca nemestrina the humeri and radii contain 5.4% more ash than the femora and tibiae. Similarly in Macaca nemestrina the bones of the hands contain 3.5% more ash than the bones of the feet, while in humans the same bones agree within 0.3% implying that adaptive use function is a factor in bone ash concentration. The ribs of Macaca nemestrina showed an unexpectedly high ash content in comparison with those of humans. In contrast with the relatively constant ash content throughout the vertebrae in humans, a conspicuous decrease axially was noted in Macaca nemestrina.

  9. Geotechnical properties of ash deposits near Hilo, Hawaii

    USGS Publications Warehouse

    Wieczorek, G.F.; Jibson, R.W.; Wilson, R.C.; Buchanan-Banks, J. M.

    1982-01-01

    Two holes were hand augered and sampled in ash deposits near Hilo, Hawaii. Color, water content and sensitivity of the ash were measured in the field. The ash alternated between reddish brown and dark reddish brown in color and had water contents as high as 392%. A downhole vane shear device measured sensitivities as high as 6.9. A series of laboratory tests including grain size distribution, Atterberg limits, X-ray diffraction analysis, total carbon determination, vane shear, direct shear and triaxial tests were performed to determine the composition and geotechnical properties of the ash. The ash is very fine grained, highly plastic and composed mostly of gibbsite and amorphous material presumably allophane. The ash has a high angle of internal friction ranging from 40-43? and is classified as medium to very sensitive. A series of different ash layers was distinguished on the basis of plasticity and other geotechnical properties. Sensitivity may be due to a metastable fabric, cementation, leaching, high organic content, and thixotropy. The sensitivity of the volcanic ash deposits near Hilo is consistent with documented slope instability during earthquakes in Hawaii. The high angles of internal friction and cementation permit very steep slopes under static conditions. However, because of high sensitivity of the ash, these slopes are particularly susceptible to seismically-induced landsliding.

  10. Vegetation establishment on soil-amended weathered fly ash

    SciTech Connect

    Semalulu, O.; Barnhisel, R.I.; Witt, S.

    1998-12-31

    A field study was conducted with the following objectives in mind: (1) to study the effect of soil addition to weathered fly ash on the establishment and survival of different grasses and legumes, (2) to identify suitable grasses and/or legume species for vegetation of fly ash, (3) to study the fertilizer N and P requirements for successful vegetation establishment on fly ash and ash-soil mixtures, (4) to examine the nutrient composition of the plant species tested, and (5) to study the plant availability of P from fly ash and ash-soil mixtures. Three rooting media were used: weathered fly ash, and 33% or 50% soil blended with the ash. Four experiments were established on each of these media to evaluate warm season grasses in pure stands, warm season grasses inter-seeded with legumes, cool season grasses, and cool season grasses inter-seeded with legumes. Soil used in this study was more acidic than the fly ash. Only the results from characterization of the rooting media, ground cover, and yield will be presented here.

  11. Retention of elemental mercury in fly ashes in different atmospheres

    SciTech Connect

    M.A. Lopez-Anton; M. Diaz-Somoano; M.R. Martinez-Tarazona

    2007-01-15

    Mercury is an extremely volatile element, which is emitted from coal combustion to the environment mostly in the vapor phase. To avoid the environmental problems that the toxic species of this element may cause, control technologies for the removal of mercury are necessary. Recent research has shown that certain fly ash materials have an affinity for mercury. Moreover, it has been observed that fly ashes may catalyze the oxidation of elemental mercury and facilitate its capture. However, the exact nature of Hg-fly ash interactions is still unknown, and mercury oxidation through fly ash needs to be investigated more thoroughly. In this work, the influence of a gas atmosphere on the retention of elemental mercury on fly ashes of different characteristics was evaluated. The retention capacity was estimated comparatively in inert and two gas atmospheres containing species present in coal gasification and coal combustion. Fly ashes produced in two pulverized coal combustion (PCC) plants, produced from coals of different rank (CTA and CTSR), and a fly ash (CTP) produced in a fluidized bed combustion (FBC) plant were used as raw materials. The mercury retention capacity of these fly ashes was compared to the retention obtained in different activated carbons. Although the capture of mercury is very similar in the gasification atmosphere and N{sub 2}, it is much more efficient in a coal combustion retention, being greater in fly ashes from PCC than those from FBC plants. 22 refs., 6 figs., 3 tabs.

  12. Use of MWC combined ash for highway embankment application

    SciTech Connect

    Shieh, C.S.; Kalajian, E.H.; Cosentino, P.; Egan, J.

    1998-07-01

    A field study was conducted to demonstrate the suitability of using municipal waste combustor (MWC) combined ash in high way embankment applications. The ash embankment was constructed using conventional techniques and was evaluated for the geotechnical properties and environmental acceptability. Field evaluation of the geotechnical performance of the embankment included specifically California Bearing Ratios (CBR), infiltration, pressuremeter, and cone penetrometer. Environmental analysis determined the ash embankment's leachate and runoff concentrations of As, Ba, Cd, Cr, Pb, Hg, Ag, and Se over time for comparison with drinking water and toxicity standards. Findings of the study indicated that combined ash could be sued as highway fill using conventional construction equipment and methods. The percent of the eight elemental metals in the ash lost to leachate or runoff after one year of exposure to natural rainfall was determined to be less than 0.01% and 0.005%, respectively, of their original weight in the ash. This indicates that greater then 99.99% of each of the eight elemental metals were retained in the ash. Concentrations of the eight EPA listed elemental metals in runoff and leachate from the ash embankment were below the EPA TCLP criteria and drinking water criteria. Results of the one-year monitoring study indicated that, based on the elemental metals examined, WMC combined ash is considered to be environmentally acceptable for highway fill materials applications.

  13. Iron-induced hydroxyl radical generation from basaltic volcanic ash

    NASA Astrophysics Data System (ADS)

    Horwell, C. J.; Fenoglio, I.; Fubini, B.

    2007-09-01

    Iron-induced hydroxyl radical generation from the surface of volcanic ash particles is a possible mechanism of respiratory toxicity in addition to crystalline silica induced pathogenicity. Here we show that volcanic ash generates hydroxyl radicals, with greater reactivity in iron-rich, silica-poor samples, such as basaltic ash. Basaltic particles expose at the surface high levels of poorly-coordinated iron ions in both Fe(II) and Fe(III) oxidation states which are likely to be the cause of such reactivity. Hitherto, basaltic ash has been disregarded as a hazard due to the lack of crystalline silica particulate but future hazard assessment should consider its toxic potential.

  14. Sulfate resistance of high calcium fly ash concrete

    NASA Astrophysics Data System (ADS)

    Dhole, Rajaram

    Sulfate attack is one of the mechanisms which can cause deterioration of concrete. In general, Class C fly ash mixtures are reported to provide poor sulfate resistance. Fly ashes, mainly those belonging to the Class C, were tested as per the ASTM C 1012 procedure to evaluate chemical sulfate resistance. Overall the Class C fly ashes showed poor resistance in the sulfate environment. Different strategies were used in this research work to improve the sulfate resistance of Class C fly ash mixes. The study revealed that some of the strategies such as use of low W/CM (water to cementing materials by mass ratio), silica fume or ultra fine fly ash, high volumes of fly ash and, ternary or quaternary mixes with suitable supplementary cementing materials, can successfully improve the sulfate resistance of the Class C fly ash mixes. Combined sulfate attack, involving physical and chemical action, was studied using sodium sulfate and calcium sulfate solutions. The specimens were subjected to wetting-drying cycles and temperature changes. These conditions were found to accelerate the rate of degradation of concrete placed in a sodium sulfate environment. W/CM was found to be the main governing factor in providing sulfate resistance to mixes. Calcium sulfate did not reveal damage as a result of mainly physical action. Characterization of the selected fly ashes was undertaken by using SEM, XRD and the Rietveld analysis techniques, to determine the relation between the composition of fly ashes and resistance to sulfate attack. The chemical composition of glass represented on the ternary diagram was the main factor which had a significant influence on the sulfate resistance of fly ash mixtures. Mixes prepared with fly ashes containing significant amounts of vulnerable crystalline phases offered poor sulfate resistance. Comparatively, fly ash mixes containing inert crystalline phases such as quartz, mullite and hematite offered good sulfate resistance. The analysis of hydrated lime

  15. Environmental hazard of oil shale combustion fly ash.

    PubMed

    Blinova, Irina; Bityukova, Liidia; Kasemets, Kaja; Ivask, Angela; Käkinen, Aleksandr; Kurvet, Imbi; Bondarenko, Olesja; Kanarbik, Liina; Sihtmäe, Mariliis; Aruoja, Villem; Schvede, Hedi; Kahru, Anne

    2012-08-30

    The combined chemical and ecotoxicological characterization of oil shale combustion fly ash was performed. Ash was sampled from the most distant point of the ash-separation systems of the Balti and Eesti Thermal Power Plants in North-Eastern Estonia. The fly ash proved potentially hazardous for tested aquatic organisms and high alkalinity of the leachates (pH>10) is apparently the key factor determining its toxicity. The leachates were not genotoxic in the Ames assay. Also, the analysis showed that despite long-term intensive oil-shale combustion accompanied by considerable fly ash emissions has not led to significant soil contamination by hazardous trace elements in North-Eastern Estonia. Comparative study of the fly ash originating from the 'new' circulating fluidized bed (CFB) combustion technology and the 'old' pulverized-fired (PF) one showed that CFB fly ash was less toxic than PF fly ash. Thus, complete transfer to the 'new' technology will reduce (i) atmospheric emission of hazardous trace elements and (ii) fly ash toxicity to aquatic organisms as compared with the 'old' technology. PMID:22717068

  16. Environmental hazard of oil shale combustion fly ash.

    PubMed

    Blinova, Irina; Bityukova, Liidia; Kasemets, Kaja; Ivask, Angela; Käkinen, Aleksandr; Kurvet, Imbi; Bondarenko, Olesja; Kanarbik, Liina; Sihtmäe, Mariliis; Aruoja, Villem; Schvede, Hedi; Kahru, Anne

    2012-08-30

    The combined chemical and ecotoxicological characterization of oil shale combustion fly ash was performed. Ash was sampled from the most distant point of the ash-separation systems of the Balti and Eesti Thermal Power Plants in North-Eastern Estonia. The fly ash proved potentially hazardous for tested aquatic organisms and high alkalinity of the leachates (pH>10) is apparently the key factor determining its toxicity. The leachates were not genotoxic in the Ames assay. Also, the analysis showed that despite long-term intensive oil-shale combustion accompanied by considerable fly ash emissions has not led to significant soil contamination by hazardous trace elements in North-Eastern Estonia. Comparative study of the fly ash originating from the 'new' circulating fluidized bed (CFB) combustion technology and the 'old' pulverized-fired (PF) one showed that CFB fly ash was less toxic than PF fly ash. Thus, complete transfer to the 'new' technology will reduce (i) atmospheric emission of hazardous trace elements and (ii) fly ash toxicity to aquatic organisms as compared with the 'old' technology.

  17. Incinerator Ash Management: Knowledge and information gaps to 1987

    SciTech Connect

    Goldin, A.; Bigelow, C.; Veneman, P.L.M.

    1992-06-01

    The Incinerator Ash Management Project at the University of Massachusetts was established in 1986 to gather written and numerical test data from existing literature and from persons knowledgeable about incinerator ash management. Information was solicited on sampling and testing methods; incinerator ash properties, and incinerator and fuel characteristics that may affect ash properties; the different components of ash management systems; and regulatory concerns. The principal data were collected on total metals, EP toxicity test results, dioxins and furans, and the composition of refuse. Cadmium and lead are apparently the most important elements affecting the ash toxicity. The values for total metals and values from the EP toxicity test are both extremely variable. Unfortunately, information about incinerator conditions at the time of sampling is often missing, which severely limits statistical interpretation of the data. The selection of an appropriate ash-management option depends on factors such as ash composition; availability, location, and nature of landfills; and the availability of alternative use or disposal techniques. Many states and the federal government are currently considering how to regulate incinerator ash management and are at various stages in this process.

  18. Probabilistic detection of volcanic ash using a Bayesian approach

    NASA Astrophysics Data System (ADS)

    Mackie, Shona; Watson, Matthew

    2014-03-01

    Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the 2010 Eyjafjalljökull eruption, much research has been carried out into techniques for discriminating ash in such data and for deriving key properties. Such techniques are generally specific to data from particular sensors, and most approaches result in a binary classification of pixels into "ash" and "ash free" classes with no indication of the classification certainty for individual pixels. Furthermore, almost all operational methods rely on expert-set thresholds to determine what constitutes "ash" and can therefore be criticized for being subjective and dependent on expertise that may not remain with an institution. Very few existing methods exploit available contemporaneous atmospheric data to inform the detection, despite the sensitivity of most techniques to atmospheric parameters. The Bayesian method proposed here does exploit such data and gives a probabilistic, physically based classification. We provide an example of the method's implementation for a scene containing both land and sea observations, and a large area of desert dust (often misidentified as ash by other methods). The technique has already been successfully applied to other detection problems in remote sensing, and this work shows that it will be a useful and effective tool for ash detection.

  19. In situ stress magnitude and rock strength in the Nankai accretionary complex: a novel approach using paired constraints from downhole data in two wells

    NASA Astrophysics Data System (ADS)

    Huffman, K. A.; Saffer, D. M.; Dugan, B.

    2016-07-01

    We present a method to simultaneously constrain both far-field horizontal stress magnitudes ( S hmin and S Hmax) and in situ rock unconfined compressive strength (UCS), using geophysical logging data from two boreholes located 70 m apart that access the uppermost accretionary prism of the Nankai subduction zone . The boreholes sample the same sediments and are affected by the same tectonic stress field, but were drilled with different annular pressures, thus providing a unique opportunity to refine estimates of both in situ stress magnitudes and rock strength. We develop a forward model to predict the angular width of compressional wellbore failures (borehole breakouts), and identify combinations of S Hmax and UCS that best match breakout widths observed in resistivity images from the two boreholes. The method requires knowledge of S hmin, which is defined by leak-off tests conducted during drilling. Our results define a normal to strike-slip stress regime from 900 to 1386 m below seafloor, consistent with observations from seismic and core data. Our analysis also suggests that in situ values of UCS are generally slightly lower that commonly assumed on the basis of published empirical relations between UCS and P-wave velocity.

  20. Wildfire Ash: Chemical Composition, Ash-Soil Interactions and Environmental Impacts

    NASA Astrophysics Data System (ADS)

    Brook, Anna; Hamzi, Seham; Wittenberg, Lea

    2015-04-01

    Of the five classical factors of soil formation, climate, parent material, topography, time, organisms, and recently recognized human activity, it is the latter factor which discretely includes fire and post-burn impact. However, it is considered that soil undergoing fire just experience a temporary removal of the top organic horizon, thus slightly modified and often labeled as 'temporarily disturbed' soil or soil 'under restoration/rehabilitation'. In fact the suggested seventh factor, post-burned produced ash, can act both dependently and independently of the other soil forming factors (Levin et al., 2013; Certini 2013). They are interdependent in cases where ash influences occur on time scales similar to 'natural' soil formation (Keesstra et ai., 2014) such as changes in vegetation. On the other hand, in post-fire areas a strong dependency is expected between soil-water retention mechanism, climate and topography. Wild-land fires exert many changes on the physical, chemical, mineralogical, biological, and morphological properties of soil that, in turn, affect the soil's hydrology and nutrient flux, modifying its ability to support vegetation and resist erosion. The ash produced by forest fires is a complex mixture composed of organic and inorganic particles characterized by vary physical-chemical and morphological properties. The importance of this study is straightforwardly related to the frequency and large-scales wildfires in Mediterranean region. In fact, wildfires are major environmental and land management concern in the world, where the number and severity of wildfires has increased during the past decades (Bodi, 2013). Certini (2013) assumed that cumulatively all of the vegetated land is burned in about 31 years annually affecting 330-430 Mha (over 3% of the Earth's surface) and wide range of land cover types worldwide including forests, peatlands, shrublands and grasslands. Whereas, the fire is identified as an important factor in soil formation, the

  1. Nutritional attributes of ash (Fraxinus spp.) outer bark and phloem and their relationships to resistance against the emerald ash borer.

    PubMed

    Hill, Amy L; Whitehill, Justin G A; Opiyo, Stephen O; Phelan, P Larry; Bonello, Pierluigi

    2012-12-01

    The emerald ash borer (Agrilus planipennis Fairmaire, EAB) is an alien, invasive wood-boring insect that is responsible for killing millions of ash trees since its discovery in North America in 2002. All North American ash species (Fraxinus spp.) that EAB has encountered have shown various degrees of susceptibility, while Manchurian ash (Fraxinus mandshurica Ruprecht), which shares a co-evolutionary history with this insect, is resistant. Recent studies have looked into constitutive resistance mechanisms in Manchurian ash, concentrating on the secondary phloem, which is the feeding substrate for the insect. In addition to specialized metabolism and defense-related components, primary metabolites and nutritional summaries can also be important to understand the feeding behavior of insect herbivores. Here, we have compared the nutritional characteristics (water content, total protein, free amino acids, total soluble sugars and starch, percent carbon and nitrogen, and macro- and micronutrients) of outer bark and phloem from black, green, white and Manchurian ash to determine their relevance to resistance or susceptibility to EAB. Water content and concentrations of Al, Ba, Cu, Fe, K, Li, tryptophan and an unknown compound were found to separate black and Manchurian ash from green and white ash in a principal component analysis (PCA), confirming their phylogenetic placements into two distinct clades. The traits that distinguished Manchurian ash from black ash in the PCA were water content and concentrations of total soluble sugars, histidine, lysine, methionine, ornithine, proline, sarcosine, tyramine, tyrosol, Al, Fe, K, Na, V and an unknown compound. However, only proline, tyramine and tyrosol were significantly different, and higher, in Manchurian ash than in black ash.

  2. Controls on accretion of flysch and mélange belts at convergent margins: Evidence from the Chugach Bay thrust and Iceworm mélange, Chugach