Sample records for buoyancy-driven rapid exhumation

  1. Exploring Titan with Autonomous, Buoyancy Driven Gliders (United States)

    Morrow, M. T.; Woolsey, C. A.; Hagerman, G. M.

    Buoyancy driven underwater gliders are highly efficient winged underwater vehicles which locomote by modifying their internal shape. The concept, which is already well-proven in Earth's oceans, is also an appealing technology for remote terrain exploration and environmental sampling on worlds with dense atmospheres. Because of their high efficiency and their gentle, vertical take-off and landing capability, buoyancy driven gliders might perform long duration, global mapping tasks as well as light-duty, local sampling tasks. Moreover, a sufficiently strong gradient in the planetary boundary layer may enable the vehicles to perform dynamic soaring, achieving even greater locomotive efficiency. Shape Change Actuated, Low Altitude Robotic Soarers (SCALARS) are an appealing alternative to more conventional vehicle technology for exploring planets with dense atmospheres. SCALARS are buoyancy driven atmospheric gliders with a twin-hulled, inboard wing configuration. The inboard wing generates lift, which propels the vehicle forward. Symmetric changes in mass distribution induce gravitational pitch moments that provide longitudinal control. Asymmetric changes in mass distribution induce twist in the inboard wing that provides directional control. The vehicle is actuated solely by internal shape change; there are no external seals and no exposed moving parts, save for the inflatable buoyancy ballonets. Preliminary sizing analysis and dynamic modeling indicate the viability of using SCALARS to map the surface of Titan and to investigate features of interest.

  2. Buoyancy-Driven Polymerase Chain Reaction (PCR) Devices

    Energy Technology Data Exchange (ETDEWEB)

    Ness, K D; Wheeler, E K; Benett, W; Stratton, P; Christian, A; Chen, A; Ortega, J; Weisgraber, T H; Goodson, K E


    Polymerase chain reaction (PCR) facilitates DNA detection by significantly increasing the concentration of specific DNA segments. A new class of PCR instruments uses a buoyancy-driven re-circulating flow to thermally cycle the DNA sample and benefits from reduced cycle times, low sample volumes, a miniaturized format, and low power consumption. This paper analyzes a specific buoyancy PCR device in a micro-channel ''race-track'' geometry to determine key parameters about PCR cycle times and other figures of merit as functions of device dimensions. The 1-D model balances the buoyancy driving force with frictional losses. A hydrostatic pressure imbalance concept is used between the left and right sides of the fluid loop to calculate the buoyancy driving force. Velocity and temperature distributions within the channels are determined from two-dimensional analysis of the channel section, with developing region effects included empirically through scaled values of the local Nusselt number. Good agreement between four independent verification steps validate the 1-D simulation approach: (1) analytical expressions for the thermal entrance length are compared against, (2) comparison with a full 3-D finite element simulation, (3) comparison with an experimental flow field characterization, and (4) calculation of the minimum PCR runtime required to get a positive PCR signal from the buoyancy-driven PCR device. The 1-D approach closely models an actual buoyancy-driven PCR device and can further be used as a rapid design tool to simulate buoyancy PCR flows and perform detailed design optimizations studies.

  3. Buoyancy driven turbulence and distributed chaos

    CERN Document Server

    Bershadskii, A


    It is shown, using results of recent direct numerical simulations, laboratory experiments and atmospheric measurements, that buoyancy driven turbulence exhibits a broad diversity of the types of distributed chaos with its stretched exponential spectrum $\\exp(-k/k_{\\beta})^{\\beta}$. The distributed chaos with $\\beta = 1/3$ (determined by the helicity correlation integral) is the most common feature of the stably stratified turbulence (due to the strong helical waves presence). These waves mostly dominate spectral properties of the vertical component of velocity field, while the horizontal component is dominated by the diffusive processes both for the weak and strong stable stratification ($\\beta =2/3$). For the last case influence of the low boundary can overcome the wave effects and result in $\\beta =1/2$ for the vertical component of the velocity field (the spontaneous breaking of the space translational symmetry - homogeneity). For the unstably stratified turbulence in the Rayleigh-Taylor mixing zone the di...

  4. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang


    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening...... and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, were measured. A bi-directional airflow rate was measured using the constant...... injection tracer gas technique. Smoke visualizations showed that the airflow patterns are highly transient and unstable, and that the airflow rate oscillates with time. Correlations between the Froude (Archimedes) number Fr (Ar) and the L/D ratio are presented. In some cases the measured airflow rates fit...

  5. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per


    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening...... and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, were measured. A bi-directional airflow rate was measured using the constant...... quite well with the Epstein's formula ratio are presented. In some cases the measured airflow rates fit quite well with the Epstein's formula but in other cases the measured data show clear deviations from the Epstein's formula. Thus, revised formulas for natural ventilation are proposed....

  6. Rigorous buoyancy driven bubble mixing for centrifugal microfluidics. (United States)

    Burger, S; Schulz, M; von Stetten, F; Zengerle, R; Paust, N


    We present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 ± 8% (100 s mixing time) and 100 ± 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 ± 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations.

  7. Rapid Oligocene Exhumation of the Western Canadian Rocky Mountains (United States)

    Szameitat, A.; Parrish, R. R.; Stuart, F. M.; Carter, A.; Fishwick, S.


    As part of the North American Cordillera the Rocky Mountains of Canada impact the deflection of weather systems and the jet stream and form a distinct barrier to Pacific moisture reaching the continental interior. The extent to which this climatic pattern extended into the past is at present uncertain, so improving our understanding of the elevation history of the Rockies is critical to determining the controls on climate change within the Northern Hemisphere. We have undertaken a comprehensive apatite (U-Th-Sm)/He and fission track study of the southeastern Canadian Cordillera, i.e. the southern Canadian Rocky Mountains, in order to provide insight into the mid to late Cenozoic uplift and exhumation history of this region. Thermal history and exhumation models of widespread low elevation samples in combination with 6 vertical profiles covering elevations from 500 up to 3100 m a.s.l. show at least 1500 m of rapid exhumation west of the Rocky Mountain Trench (RMT) during the Oligocene (Figure 1). In contrast, the ranges east of the RMT low elevation samples provide Eocene ages throughout. The data show a very different history of recent uplift of the Canadian Rockies compared to what is currently known from published work, which mostly infer that the eastern Canadian Cordillera has not experienced significant uplift since the Eocene. We propose that the most likely cause of this rock uplift was upwelling of asthenosphere around the eastward subducting Farallon Plate. This also led to the eruption of the nearby mainly Miocene Chilcotin Group flood basalts and could have caused underplating of the thin lithosphere west of the RMT, adding to the buoyancy of the plate and lifting the range. Because the Trench marks the edge of the normal thickness craton which was underthrust beneath the Rocky Mountains during the initial upper Cretaceous orogeny, the eastern Rockies have a normal lithosperic thickness. This would impede recent uplift and provides an explanation for the

  8. Experimental study of buoyancy driven natural ventilation through horizontal openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang


    An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening, respectiv......An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening......, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and that air flow rates oscillate with time. Correlations between the Froude number Fr and the L/D ratio...... of a ventilation system, but also be implemented in more detailed models, especially multi-zone models, for simulation of the performance of natural ventilation systems...

  9. Buoyancy Driven Mixing with Continuous Volumetric Energy Deposition (United States)

    Wachtor, Adam J.; Jebrail, Farzaneh F.; Dennisen, Nicholas A.; Andrews, Malcolm J.; Gore, Robert A.


    An experiment involving a miscible fluid pair is presented which transitioned from a Rayleigh-Taylor (RT) stable to RT unstable configuration through continuous volumetric energy deposition (VED) by microwave radiation. Initially a light, low microwave absorbing fluid rested above a heavier, more absorbing fluid. The alignment of the density gradient with gravity made the system stable, and the Atwood number (At) for the initial setup was approximately -0.12. Exposing the fluid pair to microwave radiation preferentially heated the bottom fluid, and caused its density to drop due to thermal expansion. As heating of the bottom fluid continued, the At varied from negative to positive, and after the system passed through the neutral stability point, At = 0, buoyancy driven mixing ensued. Continuous VED caused the At to continue increasing and further drive the mixing process. Successful VED mixing required careful design of the fluid pair used in the experiment. Therefore, fluid selection is discussed, along with challenges and limitations of data collection using the experimental microwave facility. Experimental and model predictions of the neutral stability point, and onset of buoyancy driven mixing, are compared, and differences with classical, constant At RT driven turbulence are discussed.

  10. Nonlinear optimization of buoyancy-driven ventilation flow (United States)

    Nabi, Saleh; Grover, Piyush; Caulfield, C. P.


    We consider the optimization of buoyancy-driven flows governed by Boussinesq equations using the Direct-Adjoint-Looping method. We use incompressible Reynolds-averaged Navier-Stokes (RANS) equations, derive the corresponding adjoint equations and solve the resulting sensitivity equations with respect to inlet conditions. For validation, we solve a series of inverse-design problems, for which we recover known globally optimal solutions. For a displacement ventilation scenario with a line source, the numerical results are compared with analytically obtained optimal inlet conditions available from classical plume theory. Our results show that depending on Archimedes number, defined as the ratio of the inlet Reynolds number to the Rayleigh number associated with the plume, qualitatively different optimal solutions are obtained. For steady and transient plumes, and subject to an enthalpy constraint on the incoming flow, we identify boundary conditions leading to 'optimal' temperature distributions in the occupied zone.

  11. Phenomenology of buoyancy-driven turbulence: recent results

    CERN Document Server

    Verma, Mahendra K; Pandey, Ambrish


    In this paper, we review the recent developments in the field of buoyancy-driven turbulence. Scaling and numerical arguments show that the stably-stratified turbulence with moderate stratification has kinetic energy spectrum $E_u(k) \\sim k^{-11/5}$ and the kinetic energy flux $\\Pi_u(k) \\sim k^{-4/5}$, which is called Bolgiano-Obukhov scaling. The energy flux for the Rayleigh-B\\'{e}nard convection (RBC) however is approximately constant in the inertial range that results in Kolmorogorv's spectrum ($E_u(k) \\sim k^{-5/3}$) for the kinetic energy. The phenomenology of RBC should apply to other flows where the buoyancy feeds the kinetic energy, e.g. bubbly turbulence and fully-developed Rayleigh Taylor instability. This paper also covers several models that predict the Reynolds and Nusselt numbers of RBC. Recent works show that the viscous dissipation rate of RBC scales as $\\sim \\mathrm{Ra}^{1.3}$, where $\\mathrm{Ra}$ is the Rayleigh number.

  12. Mixing and dissipation in a geostrophic buoyancy-driven circulation (United States)

    Vreugdenhil, Catherine A.; Gayen, Bishakhdatta; Griffiths, Ross W.


    Turbulent mixing and energy dissipation have important roles in the global circulation but are not resolved by ocean models. We use direct numerical simulations of a geostrophic circulation, resolving turbulence and convection, to examine the rates of dissipation and mixing. As a starting point, we focus on circulation in a rotating rectangular basin forced by a surface temperature difference but no wind stress. Emphasis is on the geostrophic regime for the horizontal circulation, but also on the case of strong buoyancy forcing (large Rayleigh number), which implies a turbulent convective boundary layer. The computed results are consistent with existing scaling theory that predicts dynamics and heat transport dependent on the relative thicknesses of thermal and Ekman boundary layers, hence on the relative roles of buoyancy and rotation. Scaling theory is extended to describe the volume-integrated rate of mixing, which is proportional to heat transport and decreases with increasing rotation rate or decreasing temperature difference. In contrast, viscous dissipation depends crucially on whether the thermal boundary layer is laminar or turbulent, with no direct Coriolis effect on the turbulence unless rotation is extremely strong. For strong forcing, in the geostrophic regime, the mechanical energy input from buoyancy goes primarily into mixing rather than dissipation. For a buoyancy-driven circulation in a basin comparable to the North Atlantic we estimate that the total rate of mixing accounts for over 95% of the mechanical energy supply, implying that buoyancy is an efficient driver of mixing in the oceans.

  13. Lagrangian chaos in three- dimensional steady buoyancy-driven flows (United States)

    Contreras, Sebastian; Speetjens, Michel; Clercx, Herman


    Natural convection plays a key role in fluid dynamics owing to its ubiquitous presence in nature and industry. Buoyancy-driven flows are prototypical systems in the study of thermal instabilities and pattern formation. The differentially heated cavity problem has been widely studied for the investigation of buoyancy-induced oscillatory flow. However, far less attention has been devoted to the three-dimensional Lagrangian transport properties in such flows. This study seeks to address this by investigating Lagrangian transport in the steady flow inside a cubic cavity differentially-heated from the side. The theoretical and numerical analysis expands on previously reported similarities between the current flow and lid-driven flows. The Lagrangian dynamics are controlled by the Péclet number (Pe) and the Prandtl number (Pr). Pe controls the behaviour qualitatively in that growing Pe progressively perturbs the integable state (Pe =0), thus paving the way to chaotic dynamics. Pr plays an entirely quantitative role in that Pr1 amplifies and diminishes, respectively, the perturbative effect of non-zero Pe. S.C. acknowledges financial support from Consejo Nacional de Ciencia y Tecnología (CONACYT).

  14. Pattern and timing of late Cenozoic rapid exhumation and uplift of the Helan Mountain,China

    Institute of Scientific and Technical Information of China (English)


    The Helan Mountain, an intraplate deformation belt in the North China Craton, is located in the northern portion of the China North-South seismic belt, and at the northwestern margin of the Ordos Block. The Cenozoic deformation history of the Helan Mountain is characterized by extension along the eastern Helan Mountain fault (EHSF), resulting in the exhumation and uplift of the Helan Mountain, relative to the rifting of the adjacent Yinchuan Basin. Here we present new apatite fission track (AFT) data from several transects adjacent to the EHSF in the central and northern Helan Mountain. AFT ages from the northern Helan Mountain (Dawukou and Zhengyiguan transects) range from 10 Ma to 89 Ma, whereas AFT ages from the southern Helan Mountain (Suyukou transect) are greater than 71 Ma. The AFT data analysis reveals initiation of rapid uplift and exhumation of the Helan Mountain at 10–12 Ma. Additionally, a plot of the AFT ages versus their mean track length shows a distinctive "boomerang" pattern indicating that the Helan Mountain experienced a discrete phase of accelerated exhumation beginning at 10-12 Ma. Spatially, AFT samples systematically increase in age away from the EHSF and are consistent with late Cenozoic exhumation that was slow in the southwestern Helan Mountain and rapid in the northeastern Helan Mountain, as well more rapid adjacent to the EHSF and slower away from the EHSF. Obviously, the spatial distribution of late Cenozoic exhumation indicates that normal faulting of the EHSF is related to southwestward tilting and rapid exhumation of the Helan Mountain beginning at 10–12 Ma. The uplift and exhumation of the Helan Mountain was a response to the intensive extension of the northwestern margin of the Ordos Block in the late Cenozoic; this occurred under a regional extensional stress field oriented NW-SE along the Yinchuan-Jilantai-Hetao and the Weihe-Shanxi graben systems adjacent to the Ordos Block.

  15. Analysis of Buoyancy-Driven Ventilation of Hydrogen from Buildings: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Barley, C. D.; Gawlik, K.; Ohi, J.; Hewett, R.


    When hydrogen gas is used or stored within a building, as with a hydrogen-powered vehicle parked in a residential garage, any leakage of unignited H2 will mix with indoor air and may form a flammable mixture. One approach to safety engineering relies on buoyancy-driven, passive ventilation of H2 from the building through vents to the outside.

  16. Experimental study of buoyancy-driven flow in a half-scale stairwell model

    Energy Technology Data Exchange (ETDEWEB)

    Zohrabian, A.S.; Mokhtarzadeh-Dehghan, M.R.; Reynolds, A.J. (Brunel Univ., Uxbridge (GB). Dept. of Mechanical Engineering); Marriott, B.S.T. (Logica EIS Ltd., London (GB))


    This paper describes an experimental study of buoyancy-driven flows of mass and energy in a half-scale model of a stairwell. Two different geometries are considered. The stairwell model forms a closed system, within which the circulation of air is maintained by the continuous operation of a heater placed in the lower floor. The rig, its instrumentation and the computerized data-logging system are described in detail. The overall features of the flow are also described. The results include the velocity and temperature distributions and the circulating volume flow. The effects of heat input rate on these parameters are also discussed. (author).

  17. CFD modelling of buoyancy-driven natural ventilation opposed by wind

    Energy Technology Data Exchange (ETDEWEB)

    Cook, M.; Ji, Y. [De Montfort Univ., Leceister (United Kingdom). Inst. of Energy and Sustainable Development; Hunt, G. [Imperial College of London, London (United Kingdom). Dept. of Civil and Environmental Engineering


    This study formed the basis for generating guidelines on how to use computational fluid dynamics (CFD) to model natural ventilation in low-energy building designs. Previous studies have investigated steady natural displacement ventilation in a single space driven by buoyancy alone. The simulations used an external flow domain which allowed airflow through inlets and outlets to be modelled without the need for boundary conditions at these locations. CFD methods were used successfully to model buoyancy-driven displacement ventilation in which wind forces oppose the flow. Simulations were then conducted for a wind assisted buoyancy-driven displacement ventilation flow. The use of boundary conditions was the basic differences in the way these simulations were modelled. It was emphasized that the simulations are for natural displacement ventilation in which wind forces oppose buoyancy. Results of analytical predictions and experimental measurements were found to be in good agreement. The small discrepancies in the interface height separating the warm stratified air from the cooler ambient layer below can be attributed to differences in the plume behaviour and performance of the gauze used for inhibiting horizontal momentum. The under-prediction in the reduced gravity of the upper layer may also be due to the small differences in plume structure. 12 refs., 1 tab., 11 figs.

  18. CO$_2$ dissolution controlled by buoyancy driven shear dispersion in a background hydrological flow

    CERN Document Server

    Unwin, H Juliette T; Woods, Andrew W


    We present an analytical and numerical study of the long-time flow which controls the dissolution of a plume of CO$_2$ following injection into an anticline structure in a deep saline aquifer of finite vertical extent. Over times of tens to thousands of years, some of the CO$_2$ will dissolve into the underlying groundwater to produce a region of relatively dense, CO$_2$ saturated water directly below the plume of CO$_2$. Continued dissolution then requires the supply of CO$_2$ unsaturated aquifer water. This may be provided by a background hydrological flow or buoyancy driven flow caused by the density contrast between the CO$_2$ saturated and unsaturated water in the aquifer. At long times, the interaction of the cross-layer diffusive mixing with the buoyancy, leads to buoyancy driven shear dispersion of the CO$_2$. With a background hydrological flow, the upstream transport of dissolved CO$_2$ by this dispersion becomes balanced by the oncoming hydrological flow so that CO$_2$ rich water can only spread a ...

  19. Modeling Diffusion and Buoyancy-Driven Convection with Application to Geological CO2 Storage

    KAUST Repository

    Allen, Rebecca


    ABSTRACT Modeling Diffusion and Buoyancy-Driven Convection with Application to Geological CO2 Storage Rebecca Allen Geological CO2 storage is an engineering feat that has been undertaken around the world for more than two decades, thus accurate modeling of flow and transport behavior is of practical importance. Diffusive and convective transport are relevant processes for buoyancy-driven convection of CO2 into underlying fluid, a scenario that has received the attention of numerous modeling studies. While most studies focus on Darcy-scale modeling of this scenario, relatively little work exists at the pore-scale. In this work, properties evaluated at the pore-scale are used to investigate the transport behavior modeled at the Darcy-scale. We compute permeability and two different forms of tortuosity, namely hydraulic and diffusive. By generating various pore ge- ometries, we find hydraulic and diffusive tortuosity can be quantitatively different in the same pore geometry by up to a factor of ten. As such, we emphasize that these tortuosities should not be used interchangeably. We find pore geometries that are characterized by anisotropic permeability can also exhibit anisotropic diffusive tortuosity. This finding has important implications for buoyancy-driven convection modeling; when representing the geological formation with an anisotropic permeabil- ity, it is more realistic to also account for an anisotropic diffusivity. By implementing a non-dimensional model that includes both a vertically and horizontally orientated 5 Rayleigh number, we interpret our findings according to the combined effect of the anisotropy from permeability and diffusive tortuosity. In particular, we observe the Rayleigh ratio may either dampen or enhance the diffusing front, and our simulation data is used to express the time of convective onset as a function of the Rayleigh ratio. Also, we implement a lattice Boltzmann model for thermal convective flows, which we treat as an analog for

  20. Buoyancy driven flow in a hot water tank due to standby heat loss

    DEFF Research Database (Denmark)

    Fan, Jianhua; Furbo, Simon


    show that the CFD model predicts satisfactorily water temperatures at different levels of the tank during cooling by standby heat loss. It is elucidated how the downward buoyancy driven flow along the tank wall is established by the heat loss from the tank sides and how the natural convection flow......Results of experimental and numerical investigations of thermal behavior in a vertical cylindrical hot water tank due to standby heat loss of the tank are presented. The effect of standby heat loss on temperature distribution in the tank is investigated experimentally on a slim 150l tank...... parts of the tank is measured by experiments and used as input to the CFD model. Water temperatures at different levels of the tank are measured and compared to CFD calculated temperatures. The investigations focus on validation of the CFD model and on understanding of the CFD calculations.The results...

  1. Buoyancy-driven instabilities of acid-base fronts: the case of a color indicator (United States)

    Riolfo, L. A.; Kuster, S.; Trevelyan, P. M. J.; El Hasi, C.; Zalts, A.; Almarcha, C.; D'Onofrio, A.; de Wit, A.


    Buoyancy-driven hydrodynamic instabilities of acid-base fronts are studied both experimentally and theoretically in the case where an aqueous solution of a strong acid is put above a denser aqueous solution of a color indicator in the gravity field. The neutralization reaction between the acid and the color indicator as well as their differential diffusion modifies the initially stable density profile in the system and can trigger convective motion both above and below the initial contact line. The type of patterns observed as well as their wavelength and the speed of the reaction front are shown to depend on the value of the initial concentrations of the acid and of the color indicator and on their ratio. A reaction-diffusion model explains how the hydrodynamic instability scenarios change when the concentration of the reactants are varied.

  2. Effects of buoyancy-driven convection on nucleation and growth of protein crystals. (United States)

    Nanev, Christo N; Penkova, Anita; Chayen, Naomi


    Protein crystallization has been studied in presence or absence of buoyancy-driven convection. Gravity-driven flow was created, or suppressed, in protein solutions by means of vertically directed density gradients that were caused by generating suitable temperature gradients. The presence of enhanced mixing was demonstrated directly by experiments with crustacyanin, a blue-colored protein, and other materials. Combined with the vertical tube position the enhanced convection has two main effects. First, it reduces the number of nucleated hen-egg-white lysozyme (HEWL) crystals, as compared with those in a horizontal capillary. By enabling better nutrition from the protein in the solution, convection results in growth of fewer larger HEWL crystals. Second, we observe that due to convection, trypsin crystals grow faster. Suppression of convection, achieved by decreasing solution density upward in the capillary, can to some extent mimic conditions of growth in microgravity. Thus, impurity supply, which may have a detrimental effect on crystal quality, was avoided.

  3. Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries

    CERN Document Server

    D'Angelo, Maria Veronica; Allain, Catherine; Rosen, Marta; Hulin, Jean-Pierre


    The influence of a small relative density difference on the displacement of two miscible liquids is studied experimentally in transparent 2D networks of micro channels. Both stable displacements in which the denser fluid enters at the bottom of the cell and displaces the lighter one and unstable displacements in which the lighter fluid is injected at the bottom and displaces the denser one are realized. Except at the lowest mean flow velocity U, the average $C(x,t)$ of the relative concentration satisfies a convection-dispersion equation. The dispersion coefficient is studied as function of the relative magnitude of fluid velocity and of the velocity of buoyancy driven fluid motion. A model is suggested and its applicability to previous results obtained in 3D media is discussed.

  4. Buoyancy-driven convection around chemical fronts traveling in covered horizontal solution layers. (United States)

    Rongy, L; Goyal, N; Meiburg, E; De Wit, A


    Density differences across an autocatalytic chemical front traveling horizontally in covered thin layers of solution trigger hydrodynamic flows which can alter the concentration profile. We theoretically investigate the spatiotemporal evolution and asymptotic dynamics resulting from such an interplay between isothermal chemical reactions, diffusion, and buoyancy-driven convection. The studied model couples the reaction-diffusion-convection evolution equation for the concentration of an autocatalytic species to the incompressible Stokes equations ruling the evolution of the flow velocity in a two-dimensional geometry. The dimensionless parameter of the problem is a solutal Rayleigh number constructed upon the characteristic reaction-diffusion length scale. We show numerically that the asymptotic dynamics is one steady vortex surrounding, deforming, and accelerating the chemical front. This chemohydrodynamic structure propagating at a constant speed is quite different from the one obtained in the case of a pure hydrodynamic flow resulting from the contact between two solutions of different density or from the pure reaction-diffusion planar traveling front. The dynamics is symmetric with regard to the middle of the layer thickness for positive and negative Rayleigh numbers corresponding to products, respectively, lighter or heavier than the reactants. A parametric study shows that the intensity of the flow, the propagation speed, and the deformation of the front are increasing functions of the Rayleigh number and of the layer thickness. In particular, the asymptotic mixing length and reaction-diffusion-convection speed both scale as square root Ra for Ra>5. The velocity and concentration fields in the asymptotic dynamics are also found to exhibit self-similar properties with Ra. A comparison of the dynamics in the case of a monostable versus bistable kinetics is provided. Good agreement is obtained with experimental data on the speed of iodate-arsenous acid fronts

  5. Modeling and Assessment of Buoyancy-Driven Stratified Airflow in High-Space Industrial Hall

    Institute of Scientific and Technical Information of China (English)

    WANG Han-qing; CHEN Ke; HU Jian-jun; KOU Guang-xiao; WANG Zhi-yong


    In industrial environment,heat sources often are contaminant sources and health threatening con-taminants are mainly passive,so a detailed understanding of airflow mode can assist in work environment hy-giene measurement and prevention.This paper presented a numerical investigation of stratified airflow scenario in a high-space industrial hall with validated commercial code and experimentally acquired boundary conditions.Based upon an actually undergoing engineering project,this study investigated the performance of the buoyancy-driven displacement ventilation in a large welding hall with big components manufactured.The results have demonstrated that stratified airflow sustained by thermal buoyancy provides zoning effect in terms of clean and polluted regions except minor stagnant eddy areas.The competition between negative buoyant jets from displace-ment radial diffusers and positive buoyant plume from bulk object constitutes the complex transport characteris-tics under and above stratification interface.Entrainment,downdraft and turbulent eddy motion complicate the upper mixing zone,but the exhaust outlet plays a less important role in the whole field flow.And the corre-sponding suggestions concerning computational stability and convergence,further improvements in modeling and measurements were given.

  6. Buoyancy-driven instability of a miscible horizontal displacement in a Hele-Shaw cell (United States)

    Haudin, F.; Riolfo, L. A.; Knaepen, B.; de Wit, A.


    In Hele-Shaw cells, viscous fingers are forming when a fluid is injected into a more viscous one. If the two fluids are reversed, with the less mobile fluid injected into the low viscosity one, the situation is expected to be stable from a viscous point of view. Nevertheless, a destabilization of the interface can be observed due to a buoyancy-driven effect if a density difference exists between the two miscible fluids. As a result, the Poiseuille profile established in the gap of the cell locally destabilizes and convection rolls are forming. In a view from above, a striped pattern is observed at the miscible interface between the two fluids. To characterize the development of this instability, we have performed an experimental study of viscously stable miscible displacements in a Hele-Shaw cell with radial injection. The displacing fluids are aqueous solutions of glycerol and the displaced ones are either dyed water or dyed glycerol solutions. The way the relative properties of the two fluids is influencing the onset time of the instability and the characteristic size of the pattern is studied. The influence of the gap width and of the flow rate on the buoyantly unstable dynamics is also characterized.

  7. A Review of Some Recent Studies on Buoyancy Driven Flows in an Urban Environment

    Directory of Open Access Journals (Sweden)

    Bodhisatta Hajra


    Full Text Available This paper reviews some recent studies (after 2000 pertaining to buoyancy driven flows in nature and thier use in reducing air pollution levels in a city (city ventilation. Natural convection flows occur due to the heating and cooling of various urban surfaces (e.g., mountain slopes, leading to upslope and downslope flows. Such flows can have a significant effect on city ventilation which has been the subject of study in the recent times due to increased pollution levels in a city. A major portion of the research reviewed here consists of natural convection flows occurring along mountain slopes, with a few studies devoted to flows along building walls. The studies discussed here primarily include field measurements and computational fluid dynamics (CFD models. This review shows that for densely populated cities with high pollution levels, natural convection flows (mountain slope or building walls can significantly aid the dispersion of pollutants. Additional studies in this area using CFD and water channel measurements can explain the physical processes involved in such flows and help improve CFD modelling. Future research should focus on a complete understanding of the mechanisms of buoyancy flows in nature and developing design guidelines for better planning of cities.

  8. Microliter-bioreactor array with buoyancy-driven stirring for human hematopoietic stem cell culture. (United States)

    Luni, Camilla; Feldman, Hope C; Pozzobon, Michela; De Coppi, Paolo; Meinhart, Carl D; Elvassore, Nicola


    This work presents the development of an array of bioreactors where finely controlled stirring is provided at the microliter scale (100-300 mul). The microliter-bioreactor array is useful for performing protocol optimization in up to 96 parallel experiments of hematopoietic stem cell (HSC) cultures. Exploring a wide range of experimental conditions at the microliter scale minimizes cost and labor. Once the cell culture protocol is optimized, it can be applied to large-scale bioreactors for stem cell production at the clinical level. The controlled stirring inside the wells of a standard 96-well plate is provided by buoyancy-driven thermoconvection. The temperature and velocity fields within the culture volume are determined with numerical simulations. The numerical results are verified with experimental velocity measurements using microparticle image velocimetry (muPIV) and are used to define feasible experimental conditions for stem cell cultures. To test the bioreactor array's functionality, human umbilical cord blood-derived CD34(+) cells were cultured for 7 days at five different stirring conditions (0.24-0.58 mums) in six repeated experiments. Cells were characterized in terms of proliferation, and flow cytometry measurements of viability and CD34 expression. The microliter-bioreactor array demonstrates its ability to support HSC cultures under stirred conditions without adversely affecting the cell behavior. Because of the highly controlled operative conditions, it can be used to explore culture conditions where the mass transport of endogenous and exogenous growth factors is selectively enhanced, and cell suspension provided. While the bioreactor array was developed for culturing HSCs, its application can be extended to other cell types.

  9. Buoyancy-driven detachment of a wall-bound pendant drop: interface shape at pinchoff and nonequilibrium surface tension. (United States)

    Lamorgese, A; Mauri, R


    We present numerical results from phase-field simulations of the buoyancy-driven detachment of an isolated, wall-bound pendant emulsion droplet acted upon by surface tension and wall-normal buoyancy forces alone. Our theoretical approach follows a diffuse-interface model for partially miscible binary mixtures which has been extended to include the influence of static contact angles other than 90^{∘}, based on a Hermite interpolation formulation of the Cahn boundary condition as first proposed by Jacqmin [J. Fluid Mech. 402, 57 (2000)JFLSA70022-112010.1017/S0022112099006874]. In a previous work, this model has been successfully employed for simulating triphase contact line problems in stable emulsions with nearly immiscible components, and, in particular, applied to the determination of critical Bond numbers for buoyancy-driven detachment as a function of static contact angle. Herein, the shapes of interfaces at pinchoff are investigated as a function of static contact angle and distance to the critical condition. Furthermore, we show numerical results on the nonequilibrium surface tension that help to explain the discrepancy between our numerically determined static contact angle dependence of the critical Bond number and its sharp-interface counterpart based on a static stability analysis of equilibrium shapes after numerical integration of the Young-Laplace equation. Finally, we show the influence of static contact angle and distance to the critical condition on the temporal evolution of the minimum neck radius in the necking regime of drop detachment.

  10. Differential diffusion effects on buoyancy-driven instabilities of acid-base fronts: the case of a color indicator. (United States)

    Kuster, S; Riolfo, L A; Zalts, A; El Hasi, C; Almarcha, C; Trevelyan, P M J; De Wit, A; D'Onofrio, A


    Buoyancy-driven hydrodynamic instabilities of acid-base fronts are studied both experimentally and theoretically in the case where an aqueous solution of a strong acid is put above a denser aqueous solution of a color indicator in the gravity field. The neutralization reaction between the acid and the color indicator as well as their differential diffusion modifies the initially stable density profile in the system and can trigger convective motions both above and below the initial contact line. The type of patterns observed as well as their wavelength and the speed of the reaction front are shown to depend on the value of the initial concentrations of the acid and of the color indicator and on their ratio. A reaction-diffusion model based on charge balances and ion pair mobility explains how the instability scenarios change when the concentration of the reactants are varied.

  11. It takes three to tango: 1. Simulating buoyancy-driven flow in the presence of large viscosity contrasts (United States)

    Suckale, Jenny; Nave, Jean-Christophe; Hager, Bradford H.


    Buoyancy-driven flow is of fundamental importance for numerous geodynamic phenomena. Since the equations of motion governing multiphase flow are rarely amenable to analytical solutions, numerical simulations provide a compelling alternative. They offer the ability to carefully analyze flow phenomena under differing regimes, initial conditions, and flow dynamics. The three key challenges in these computations are (1) the accurate solution of the equations of motion in the presence of large viscosity contrasts, (2) the representation of strongly deforming interfaces between different fluids, and (3) the accurate coupling of fluid and interface solver. In three dimensions, these challenges become even more intricate, and the appropriate choice of numerical scheme has a profound influence on the tractability, accuracy, robustness, and efficiency of the computational simulation. This is the first paper of two that examine numerical simulations of buoyancy-driven flow in the presence of large viscosity contrasts. In this paper, we present our numerical approach which tackles the above three main challenges through a combination of three numerical methods, namely, (1) an extended ghost fluid type discretization which we developed specifically for the Stokes regime, (2) the level set method, and (3) the extension velocity technique. We find that all three components are crucial to obtain a versatile numerical tool for simulating complex structures in evolving flow. We validate our code by reproducing four benchmark problems in two and three dimensions. We devote special attention to comparing our method to other existing techniques, detailing the advantages of this approach. Finally, we highlight several types of geophysical flow problems for which we believe our method to be well suited.

  12. Passive urban ventilation by combined buoyancy-driven slope flow and wall flow: Parametric CFD studies on idealized city models (United States)

    Luo, Zhiwen; Li, Yuguo


    This paper reports the results of a parametric CFD study on idealized city models to investigate the potential of slope flow in ventilating a city located in a mountainous region when the background synoptic wind is absent. Examples of such a city include Tokyo in Japan, Los Angeles and Phoenix in the US, and Hong Kong. Two types of buoyancy-driven flow are considered, i.e., slope flow from the mountain slope (katabatic wind at night and anabatic wind in the daytime), and wall flow due to heated/cooled urban surfaces. The combined buoyancy-driven flow system can serve the purpose of dispersing the accumulated urban air pollutants when the background wind is weak or absent. The microscopic picture of ventilation performance within the urban structures was evaluated in terms of air change rate (ACH) and age of air. The simulation results reveal that the slope flow plays an important role in ventilating the urban area, especially in calm conditions. Katabatic flow at night is conducive to mitigating the nocturnal urban heat island. In the present parametric study, the mountain slope angle and mountain height are assumed to be constant, and the changing variables are heating/cooling intensity and building height. For a typical mountain of 500 m inclined at an angle of 20° to the horizontal level, the interactive structure is very much dependent on the ratio of heating/cooling intensity as well as building height. When the building is lower than 60 m, the slope wind dominates. When the building is as high as 100 m, the contribution from the urban wall flow cannot be ignored. It is found that katabatic wind can be very beneficial to the thermal environment as well as air quality at the pedestrian level. The air change rate for the pedestrian volume can be as high as 300 ACH.

  13. Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow. (United States)

    Hu, L H; Huo, R; Yang, D


    The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons--a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

  14. Numerical Investigation of Heat Transfer with Thermal Radiation in an Enclosure in Case of Buoyancy Driven Flow

    Directory of Open Access Journals (Sweden)

    Christoph Hochenauer


    Full Text Available The purpose of this paper is to investigate state of the art approaches and their accuracy to compute heat transfer including radiation inside a closed cavity whereas buoyancy is the only driving force. This research is the first step of an all-embracing study dealing with underhood airflow and thermal management of vehicles. Computational fluid dynamic (CFD simulation results of buoyancy driven flow inside a simplified engine compartment are compared to experimentally gained values. The test rig imitates idle condition without any working fan. Thus, the airflow is only driven by natural convection. A conventional method used for these applications is to compute the convective heat transfer coefficient and air temperature using CFD and calculate the wall temperature separately by performing a thermal analysis. The final solution results from coupling two different software tools. In this paper thermal conditions inside the enclosure are computed by the use of CFD only. The impact of the turbulence model as well as the results of various radiation models are analyzed and compared to the experimental data.

  15. DNS of buoyancy-driven flows and Lagrangian particle tracking in a square cavity at high Rayleigh numbers

    Energy Technology Data Exchange (ETDEWEB)

    Puragliesi, R., E-mail: [Nuclear Energy and Safety Research Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Laboratoire d' Ingenierie Numerique, Ecole Polytechnique Federale de Lausanne, Station 9, CH-1015 Lausanne (Switzerland); Dehbi, A., E-mail: [Nuclear Energy and Safety Research Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Leriche, E., E-mail: [Universite de Lyon, F-42023 Saint-Etienne, LMFA-UJM St-Etienne, CNRS UMR 5509 Universite de St-Etienne, 23 rue Docteur Paul Michelon, F-42023 Saint-Etienne (France); Soldati, A., E-mail: [Dipartimento di Energetica e Macchine, Universita di Udine, Via delle Scienze 208, IT-33100 Udine (Italy); Deville, M.O., E-mail: [Laboratoire d' Ingenierie Numerique, Ecole Polytechnique Federale de Lausanne, Station 9, CH-1015 Lausanne (Switzerland)


    Highlights: > 2D study of micro-size particle depletion driven by chaotic natural convective flows in square domains. > Description of velocity and temperature first and second moments with changing in the Rayleigh number. > Strong decoupling between the turbulent kinetic energy and the dissipation rate. > Particle recirculation sustained by the vertical hot boundary layer. > Deposition mostly induced by gravity, thermophoretic and lift forces are negligible. - Abstract: In this work we investigate numerically particle deposition in the buoyancy driven flow of the differentially heated cavity (DHC). We consider two values of the Rayleigh number (Ra = 10{sup 9}, 10{sup 10}) and three values of the particle diameter (d{sub p} = 15, 25, 35 [{mu}m]). We consider the cavity filled with air and particles with the same density of water {rho}{sub w} = 1000 [kg/m{sup 3}] (aerosol). We use direct numerical simulations (DNS) for the continuous phase, and we solve transient Navier-Stokes and energy transport equations written in an Eulerian framework, under the Boussinesq approximation, for the viscous incompressible Newtonian fluid with constant Prandtl number (Pr = 0.71). First- and second-order statistics are presented for the continuous phase as well as important quantities like turbulent kinetic energy (TKE) and temperature variance with the associated production and dissipation fields. The TKE production shows different behaviour at the two Rayleigh numbers. The Lagrangian approach has been chosen for the dispersed phase description. The forces taken into account are drag, gravity, buoyancy, lift and thermophoresis. A first incursion in the sedimentation mechanisms is presented. Current results indicate that the largest contribution to particle deposition is caused by gravitational settling, but a strong recirculating zone, which liftoffs and segregates particles, contributes to decrease settling. Deposition takes place mostly at the bottom wall. The influence of lift

  16. Evidence for Rapid Post-Pliocene Exhumation of the Santa Monica Mountains, California, from Apatite (U-Th)/He Thermochronometry (United States)

    Niemi, N. A.; Clark, M. K.; Yakovlev, P. V.


    Potential losses related to large earthquakes on blind or previously unrecognized thrust faults is of significant concern to southern California, where numerous individual mountain ranges are underlain by active faults. Some of the most hazardous thrust fault systems in Southern California are associated with high-slip-rate faults in the northern portion of the western Transverse Ranges, while the southern region is generally considered to be less seismically active. Determining slip rates on faults bounding the Santa Monica Mountains has been challenging, in part because many of the faults that underlie the range have submarine surface traces. Existing geologic studies predict that these faults slip relatively slowly; however, recent GPS models predict a band of relatively fast contraction on faults that lie beneath the Santa Monica Mountains (Marshall et al., 2013). These geodetic models suggest unrecognized hazard associated with shortening and vertical uplift of this range. Late Cenozoic strata in the central Santa Monica Mountains are of sufficient thickness to bury Cretaceous and Paleocene strata above the closure temperature for apatite (U-Th)/He thermochronometry (~70°C). As a result, these older rocks, now exposed in the southern Santa Monica Mountains, may record exhumation associated with fault slip and associated structural deformation of the range. Preliminary apatite (U-Th)/He ages near Las Flores Canyon span from 3.5 to 6.5 Ma, and are the youngest apatite (U-Th)/He ages we are aware of in southern California outside of the transpressional San Andreas system. When plotted as depth beneath the base of the marine Modelo Formation, an inflection in age/depth gradient at 4 Ma is inferred to reflect the onset of fault motion and is consistent with the late Miocene age of the Modelo Formation. Based on average geothermal gradients for the Ventura and Los Angeles basins and an assumed thrust fault dip of 20°, observed apparent exhumation rates are

  17. Experimental study on buoyancy-driven exchange flows through breaches of a tokamak vacuum vessel in a fusion reactor under the loss-of-vacuum-event conditions

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Kazuyuki; Tomoaki, Kunugi; Ogawa, Masurou; Seki, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)


    As one of thermofluid safety studies in the International Thermonuclear Experimental Reactor, buoyancy-driven exchange flow behavior through breaches of a vacuum vessel (VV) has been investigated quantitatively by using a preliminary loss-of-vacuum-event (LOVA) apparatus that simulated the tokamak VV of a fusion reactor with a small-scaled model. To carry out the present experiments under the atmospheric pressure condition, helium gas and air were provided as the working fluids. The inside of the VV was initially filled with helium gas and the outside was atmosphere. The breaches on the VV under the LOVA condition were simulated by opening six simulated breaches to which were set the different positions on the VV. When the buoyancy-driven exchange flow through the breach occurred, helium gas went out from the inside of the VV through the breach to the outside and air flowed into the inside of the VV through the breach from the outside. The exchange rate in the VV between helium gas and air was calculated from the measured weight change of the VV with time since the experiment has started. experimental parameters were breach position, breach number, breach length, breach size, and breach combination. The present study clarifies that the relation between the exchange rate and the breach position of the VV depended on the magnitude of the potential energy from the ground level to the breach position, and then, the exchange rate decreased as the breach length increased and as the breach size decreased.

  18. Buoyancy-driven Magnetohydrodynamic Waves (United States)

    Hague, A.; Erdélyi, R.


    Turbulent motions close to the visible solar surface may generate low-frequency internal gravity waves (IGWs) that propagate through the lower solar atmosphere. Magnetic activity is ubiquitous throughout the solar atmosphere, so it is expected that the behavior of IGWs is to be affected. In this article we investigate the role of an equilibrium magnetic field on propagating and standing buoyancy oscillations in a gravitationally stratified medium. We assume that this background magnetic field is parallel to the direction of gravitational stratification. It is known that when the equilibrium magnetic field is weak and the background is isothermal, the frequencies of standing IGWs are sensitive to the presence of magnetism. Here, we generalize this result to the case of a slowly varying temperature. To do this, we make use of the Boussinesq approximation. A comparison between the hydrodynamic and magnetohydrodynamic cases allows us to deduce the effects due to a magnetic field. It is shown that the frequency of IGWs may depart significantly from the Brunt-Väisälä frequency, even for a weak magnetic field. The mathematical techniques applied here give a clearer picture of the wave mode identification, which has previously been misinterpreted. An observational test is urged to validate the theoretical findings.

  19. Revised exhumation history of the Wind River Range, WY, and implications for Laramide tectonics (United States)

    Stevens, Andrea L.; Balgord, Elizabeth A.; Carrapa, Barbara


    A reanalysis of apatite fission track (AFT) thermochronology coupled with thermal-kinetic modeling of samples from the Wind River Range document Late Cretaceous to early Eocene episodic cooling and exhumation of one of the largest basement-cored ranges in the western United States. Three vertical transects taken at different latitudes along the length of the 145 km Wind River Range reveal that exhumation is uniform along strike suggesting steady displacement along the Wind River Fault, and significant exhumation and relief in the Wind River Range by the early Eocene. Thermal modeling of AFT ages, lengths, and compositional proxies document rapid exhumation from ~65 to 50 Ma. This rapid exhumation episode matches a period of accelerated subsidence in the adjacent Green River and Wind River basins. At ~50 Ma, exhumation dramatically slowed by an order of magnitude coincident with decreasing subsidence in the adjacent basins. No signal of Oligocene cooling is apparent in either AFT cooling ages or thermal modeling suggesting that a possible later phase of reactivation of structures and uplift, as previously suggested, was limited to less than approximately 1 km of exhumation.

  20. Energy spectrum of buoyancy-driven turbulence

    KAUST Repository

    Kumar, Abhishek


    Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux Πu, we demonstrate that, for stably stratified flows, the kinetic energy spectrum Eu(k)∼k-11/5, the potential energy spectrum Eθ(k)∼k-7/5, and Πu(k)∼k-4/5 are consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence Eu(k) follows Kolmogorov\\'s spectrum with a constant energy flux. For Rayleigh-Bénard convection, we show that the energy supply rate by buoyancy is positive, which leads to an increasing Πu(k) with k, thus ruling out Bolgiano-Obukhov scaling for the convective turbulence. Our numerical results show that convective turbulence for unit Prandt number exhibits a constant Πu(k) and Eu(k)∼k-5/3 for a narrow band of wave numbers. © 2014 American Physical Society.

  1. Rheologic Transitions During Exhumation of High-Pressure Metamorphic Rocks (United States)

    Whitney, D. L.; Teyssier, C. P.; Rey, P. F.


    The exhumation of deeply buried rocks typically involves dynamic feedbacks between deformation and metamorphic reactions (+ fluid and/or melt) that influence rheology and facilitate or drive large-magnitude exhumation. The evolution of grain-scale to terrane-scale processes during decompression can be seen in rocks exhumed from oceanic and continental subduction and from orogenic crust. In the Sivrihisar (Turkey) high-P/low-T (oceanic subduction) complex, microstructures record deformation and syn-kinematic reactions during decompression from eclogite to blueschist facies conditions; this transformation resulted in dramatic strength reduction that promoted strain localization along the subduction interface. In quartz-rich rocks, qz was deformed in the dislocation creep regime and records transitions in microstructure and slip systems during near-isothermal decompression from 2.5 to 1.5 GPa; these transitions may be related to decreasing water fugacity over tens of km of decompression. High-to ultrahigh-P eclogite in exhumed continental subduction zones such as the Western Gneiss Region (Norway) record decompression from >2.5 GPa to crust, upper crustal extension/transtension drives rapid ascent of the deep crust to form migmatite-cored domes. The exhuming deep crust entrains HP relics such as eclogite (e.g. Montagne Noire dome, France) as it traverses much of the orogenic crust, from >1.2 GPa to (in some cases) crust reaches the near-surface. In summary, decompression of subducted or deeply buried crust systematically leads to rheologic transitions and feedbacks between deformation and metamorphism in the presence of aqueous fluid and/or melt.

  2. Measuring plume-related exhumation of the British Isles in Early Cenozoic times (United States)

    Cogné, Nathan; Doepke, Daniel; Chew, David; Stuart, Finlay M.; Mark, Chris


    Mantle plumes have been proposed to exert a first-order control on the morphology of Earth's surface. However, there is little consensus on the lifespan of the convectively supported topography. Here, we focus on the Cenozoic uplift and exhumation history of the British Isles. While uplift in the absence of major regional tectonic activity has long been documented, the causative mechanism is highly controversial, and direct exhumation estimates are hindered by the near-complete absence of onshore post-Cretaceous sediments (outside Northern Ireland) and the truncated stratigraphic record of many offshore basins. Two main hypotheses have been developed by previous studies: epeirogenic exhumation driven by the proto-Iceland plume, or multiple phases of Cenozoic compression driven by far-field stresses. Here, we present a new thermochronological dataset comprising 43 apatite fission track (AFT) and 102 (U-Th-Sm)/He (AHe) dates from the onshore British Isles. Inverse modelling of vertical sample profiles allows us to define well-constrained regional cooling histories. Crucially, during the Paleocene, the thermal history models show that a rapid exhumation pulse (1-2.5 km) occurred, focused on the Irish Sea. Exhumation is greatest in the north of the Irish Sea region, and decreases in intensity to the south and west. The spatial pattern of Paleocene exhumation is in agreement with the extent of magmatic underplating inferred from geophysical studies, and the timing of uplift and exhumation is synchronous with emplacement of the plume-related British and Irish Paleogene Igneous Province (BIPIP). Prior to the Paleocene exhumation pulse, the Mesozoic onshore exhumation pulse is mainly linked to the uplift and erosion of the hinterland during the complex and long-lived rifting history of the neighbouring offshore basins. The extent of Neogene exhumation is difficult to constrain due to the poor sensitivity of the AHe and AFT systems at low temperatures. We conclude that the

  3. Late Cenozoic exhumation of New Zealand: inversion from bedrock thermochronological ages (United States)

    Jiao, Ruohong; Herman, Frédéric; Seward, Diane


    In the SW Pacific, the present subaerial land area of New Zealand straddles the boundary between the Australian and Pacific Plates. This margin has been converging since the mid-Eocene-late Oligocene, leading to a period of widespread crustal deformation and exhumation. During the past decades, the exhumation of the New Zealand basement has been the basis of many thermochronological studies, resulting in a large number of data from the Palaeozoic and Mesozoic bedrocks. We compiled the cooling ages from multiple thermochronological systems (i.e. apatite and zircon (U-Th)/He, apatite and zircon fission-track, K-feldspar, muscovite, biotite and hornblende 40Ar/39Ar or K-Ar) that yielded cooling events younger than 25 Ma, and formally inverted this data set to estimate the large-scale temporal and spatial variations in the exhumation rates of New Zealand during the late Cenozoic. The exhumation results show good agreement with the predicted off-shore sedimentation rates, while the thermal model used in the inversion is in part constrained by the present-day observed surface heat flow. The modelling results indicate crustal exhumation from the earliest Miocene (just prior to 20 Ma). But from ~10 Ma, a moderate acceleration of exhumation is observed at most sites, coincident with an important change in the orientation of the Pacific motion relative to the Australian Plate. Since the Quaternary, rapid exhumation has occurred in the Southern Alps along the west coast of South Island, with the highest rates in the central part of range. In this region, our estimates of the million-year-scale exhumation rates are in general coincidence with those previously estimated over shorter (i.e. 0.1 Ma and 10 ka) time scales, as well as with the contemporary rock uplift rates derived from GPS data, confirming exhumational steady-state in the orogeny. In contrast in eastern North Island, the predicted Quaternary exhumation rates are much lower than the recent rock uplift rates measured

  4. Exhumation history of the Serra do Mar, southeast Brazil (United States)

    Carina Siqueira-Ribeiro, Marli; Hackspacher, Peter; Stuart, Finlay M.


    The Serra do Mar (SM) mountain range located along the southeast Brazilian continental margin is characterized by a low-lying coastal plateau separated from the elevated inland plateau by a steep escarpment. This morphology is a result of reactivation of Precambrian shear zones since the break-up of the Western Gondwana and opening of the South Atlantic Ocean in Early Cretaceous (1). Previous Thermochronological data from southeast Brazilian highlands (2,3), indicates that the landscape evolution is associated with several distinct exhumation events. In order to clarify the intensity and duration of the post-break up tectonic processes that shaped the SM we have undertaken a low temperature thermochronology study of crystalline basement, from the plateaus and escarpments situated between south of Rio de Janeiro and São Paulo state. Apatite fission track (AFT) and (U-Th/He) and (AHe) dating has been combined with geologic information to generate precise thermal histories and make initial attempts to quantify the amount of exhumation. AFT ages range from 145 to 53 Ma whereas preliminary AHe ages range from 75 to 37 Ma. Forward modeling using QTQt confirms Late Cretaceous-Paleogene cooling identified earlier (4,5) and identifies a distinct cooling phase in Neogene, between 30 and 10 Ma. Neogene cooling rapid caused exhumation of rocks 1 km through of the crust mainly in south portion of the SM in Rio de Janeiro state. (1) Almeida, 1976. An. Academia Bras de Cien 48 (suppl.), 15-(2) (2) Hackspacher et al. 2004. Gondwana Research,vol.2, 91-101. (3) Hiruma et al. 2010. Gondwana Research,18,674-687. (4) Siqueira-Ribeiro et al. 2011. Revista Bras. de Geomorfologia, 13, 3-14 (5) Cogné et al. 2012. Journal Geophysical Research, vol.117,1-16.

  5. Pliocene eclogite exhumation at plate tectonic rates in eastern Papua New Guinea. (United States)

    Baldwin, Suzanne L; Monteleone, Brian D; Webb, Laura E; Fitzgerald, Paul G; Grove, Marty; Hill, E June


    As lithospheric plates are subducted, rocks are metamorphosed under high-pressure and ultrahigh-pressure conditions to produce eclogites and eclogite facies metamorphic rocks. Because chemical equilibrium is rarely fully achieved, eclogites may preserve in their distinctive mineral assemblages and textures a record of the pressures, temperatures and deformation the rock was subjected to during subduction and subsequent exhumation. Radioactive parent-daughter isotopic variations within minerals reveal the timing of these events. Here we present in situ zircon U/Pb ion microprobe data that dates the timing of eclogite facies metamorphism in eastern Papua New Guinea at 4.3 +/- 0.4 Myr ago, making this the youngest documented eclogite exposed at the Earth's surface. Eclogite exhumation from depths of approximately 75 km was extremely rapid and occurred at plate tectonic rates (cm yr(-1)). The eclogite was exhumed within a portion of the obliquely convergent Australian-Pacific plate boundary zone, in an extending region located west of the Woodlark basin sea floor spreading centre. Such rapid exhumation (> 1 cm yr(-1)) of high-pressure and, we infer, ultrahigh-pressure rocks is facilitated by extension within transient plate boundary zones associated with rapid oblique plate convergence.

  6. Late Cretaceous-Cenozoic exhumation history of Tiantangzhai region of Dabieshan Orogen: Constraints from (U-Th)/He and fission track analysis

    Institute of Scientific and Technical Information of China (English)


    Integrated fission track and (U-Th)/He analysis is carried out on 6 apatite and 6 zircon samples from a near vertical section in The Tiantangzhai region at the core of the present Dabieshan orogen. The result shows that the region experienced cooling/exhumation during the Late Cretaceous and Early Tertiary period. Age-elevation relationships for different dating systems and different minerals suggest a pulse of rapid exhumation at ~110 Ma before present, preserved in the structurally highest samples. At lower elevations, ages begin to decrease with decreasing elevation, suggesting lower exhumation rates since 90 Ma. Two periods of different exhumation rates are identified since 90 Ma. The average apparent exhumation rate for the period of 43.4-22.5 is 0.062 km/Ma, whereas that for the period of 76.4-47.4 Ma is 0.039 km/Ma.

  7. Crustal Structure Linked to Ultra-High-Pressure Rock Exhumation: A Model for the Tso Morari Complex (United States)

    Jamieson, R. A.; Beaumont, C.; Butler, J. P.; Warren, C. J.


    Many syn-collisional ultra-high-pressure (UHP) complexes display an array of upper-crustal structures suggesting that doming accompanied by coeval normal and thrust faulting is closely linked to UHP exhumation processes. We present a geodynamical model that accounts for structural, metamorphic, and geochronological data from UHP terranes in terms of crustal burial and exhumation in a subduction channel below an accretionary wedge. Competition between down-channel shear traction and up-channel buoyancy forces, expressed as the exhumation number, E, controls crustal subduction and exhumation, leading to rapid up-channel flow when E > 1. In some cases, transient slab rollback can lead to incorporation of deep mantle peridotite into the subduction channel. Exhuming UHP material forms a nappe stack and structural dome as it penetrates and destabilises the overlying wedge, driving thrusting and extension. The Tso Morari complex, Ladakh, is a structural dome cored by UHP rocks that were metamorphosed and exhumed during the early stages of the Himalayan collision (ca. 55-45 Ma). Results from a high-resolution numerical model, in which convergence velocity decreases from 15 cm/a to 5 cm/a during the early stages of collision, are consistent with a wide range of structural, metamorphic, and geochronological data from Tso Morari. We conclude that the model offers a viable explanation for the geological evolution of syn-collisional UHP complexes. Moreover, the model demonstrates that buoyant exhumation from deep in the subduction channel is responsible for observed upper-crustal structures, which therefore hold important (but commonly overlooked) clues to UHP exhumation processes.

  8. Spatial variations in focused exhumation along a continental-scale strike-slip fault: The Denali fault of the eastern Alaska Range (United States)

    Benowitz, J.A.; Layer, P.W.; Armstrong, P.; Perry, S.E.; Haeussler, P.J.; Fitzgerald, P.G.; VanLaningham, S.


    40Ar/39Ar, apatite fission-track, and apatite (U-Th)/He thermochronological techniques were used to determine the Neogene exhumation history of the topographically asymmetric eastern Alaska Range. Exhumation cooling ages range from ~33 Ma to ~18 Ma for 40Ar/39Ar biotite, ~18 Ma to ~6 Ma for K-feldspar minimum closure ages, and ~15 Ma to ~1 Ma for apatite fission-track ages, and apatite (U-Th)/He cooling ages range from ~4 Ma to ~1 Ma. There has been at least ~11 km of exhumation adjacent to the north side of Denali fault during the Neogene inferred from biotite 40Ar/39Ar thermochronology. Variations in exhumation history along and across the strike of the fault are influenced by both far-field effects and local structural irregularities. We infer deformation and rapid exhumation have been occurring in the eastern Alaska Range since at least ~22 Ma most likely related to the continued collision of the Yakutat microplate with the North American plate. The Nenana Mountain region is the late Pleistocene to Holocene (~past 1 Ma) primary locus of tectonically driven exhumation in the eastern Alaska Range, possibly related to variations in fault geometry. During the Pliocene, a marked increase in climatic instability and related global cooling is temporally correlated with an increase in exhumation rates in the eastern Alaska Range north of the Denali fault system.

  9. An integrated approach to study the exhumation of rocks in Neelum valley, NW Himalayas, Pakistan. (United States)

    Turab, Syed Ali; Stüwe, Kurt; Stuart, Finlay M.; Chew, David M.


    Tectonics and erosion have both been suggested as alternative driving mechanisms for rapid exhumation of rocks in the western Himalayan syntaxis. This debate could be resolved by understanding the plan view-geometry of the exhumation of rocks in the region: does it follow the major structures?, or is it related to the drainage geometry? In order to resolve this geometry we have undertaken a low-temperature thermochronologic study, using crystalline rocks, of a critical region of the western syntaxis: Neelum valley region, Pakistan. Apatite (U-Th-Sm)/He (AHe), fission track (AFT) and U-Pb dating has been combined with geomorphic stream power analysis in order to discern the relationship of exhumation of rocks to tectonics (main faults) or erosion. Pooled AFT ages show a range of 2.2 ± 0.4 to 7.0 ± 0.4 Ma (1σ). Recoil corrected AHe ages exhibit a range from 2.0 ± 0.1 to 8.7 ± 0.5 Ma (1σ). U-Pb ages could be used to divide the samples in three groups: ages that are completely-, partly- and not- affected by Himalayan tectonics. The range of apatite U-Pb ages displayed by both completely- and partly- affected samples is from 17.0 to 43.0 Ma (2σ, unanchored, i.e. constrained by isochrones alone) and 6.0 to 48.3 Ma (2σ, anchored using the Stacey and Kramers terrestrial Pb evolution model). Stream power analysis of the Neelum river catchment indicates a region with high steepness index (Ksn, normalized to reference concavity, θref = 0.45) values of > 500 m0.9 which coincides well the region sampled. In combination with earlier published ages, our data indicate that exhumation contours run more or less parallel to the major structures in the region. The boundary between samples with unaffected and affected U-Pb ages as well as transition from high Ksn to lower Ksn values along the main Neelum river fits well with the mapped trace of the Main Central Thrust (MCT), corroborating the presence of the MCT in the southeastern parts of our study area. Thermal history


    Restrepo-Moreno, S. A.; Foster, D. A.; O'Sullivan, P. B.; Donelick, R.; Stockli, D. F.


    The Antioqueño plateau (AP), in the northernmost Cordillera Central, Colombia, is the most extensive and best preserved relict surface in the Northern Andes. Apatite (U-Th)/He (AHe) and fission track (AFT) results from twenty two samples, collected from paleocrustal depths along two vertical profiles in canyons dissecting the AP, constrain Cenozoic erosional exhumation of this segment of the Andean range. The two profiles exhibit excellent reproducibility of AHe and AFT data. Helium ages increase with elevation from ~22-49 Ma. A marked inflection point in the AHe age-elevation plots at 25 Ma defines the bottom of the post-Oligocene He partial retention zone (PRZ). Virtually invariant ages at ~25 Ma record onset of rapid exhumation in the AP. A more subtle slope change in the PRZ at ~43 Ma is interpreted as a minor exhumation pulse. AFT better defines timing and intensity of Eocene exhumation. AFT ages for both profiles vary from ~30-49 Ma and are consistently older than AHe ages. AFT data display invariant ages (±2σ) between 1500-2400 m elevations while confined track length data exhibit uni-modal distributions with a mean track length of ~14.2 μm. Both facts indicate rapid cooling. This is further supported by virtually concordant AFT and AHe ages for both profiles between 1500 to 2200 m implying that rocks were exhumed from temperatures >120°C to below AHe closure temperature 60°C. Assuming a geothermal gradient of ~25°C/km this corresponds to exhumation rates in the order of 0.5 mm/y, comparable in intensity to the Miocene pulse defined by AHe. Integrated thermal modeling show an episode of rapid cooling at ~43-49 Ma. AFT profiles show an apparent inflection point at ~1400 m, which defines the upper boundary of an apatite partial annealing zone (PAZ) exhumed during the 43-49 Ma cooling event. The position of the PAZ and PRZ relative to the present erosional surface point to average erosion rates of ~0.03 mm/yr, which constitute very low denudation rates

  11. Cretaceous Exhumation of the North American Cordillera Measured through Mineral Multi-Dating: Insights into Basin Filling Models and Orogenic Architecture (United States)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.; Gehrels, G. E.; Thomson, S. N.


    Apatite fission track (AFT) thermochronology is an effective thermochronometer to measure source exhumation in the North American Cordillera, western U.S.A. We use a combination of thermochronology and geochronology to measure lag times, i.e., the difference in time between the cooling and depositional ages of a mineral crystal. These lag-time measurements using source exhumation ages, measured with AFT thermochronology, and depositional ages, measured with biostratigraphy and detrital zircon U-Pb geochronology, indicate constant to decreasing lag times of 0-5 m.y. throughout the Cretaceous. These lag times are consistent with rapid exhumation rates of ~0.9->1 km/m.y. One pitfall of using detrital thermochronology to measure source exhumation is assuring that the apatite crystals are exhumed apatites and not volcanic apatites introduced into the system from the volcanic arc. To do this we use U-Pb geochronology to remove samples contaminated with young arc derived apatites and keep those with old exhumed apatites. Five of the seven detrital AFT samples were significantly contaminated with young volcanic apatites, showing that U-Pb geochronology should be a routine step in measuring lag times. Our findings demonstrate that coarse-grained foreland basin deposits in the Cretaceous Western Interior, in both the proximal and distal settings, were deposited during times of active tectonism and exhumation and that sediments are not stored in wedge-top and proximal foredeep settings for long periods of time, i.e. >5 m.y., and then subsequently reworked distally. Exhumation rates of ~0.9->1 km/m.y. are not sustainable over the entire orogenic belt for the duration of the Sevier orogeny, indicated by the lack of deep-crustal material exhumed in the North American Cordillera. High exhumation rates were likely concentrated over the eastward-propagating Sevier fold-thrust belt, whereas the Nevadaplano and hinterland experienced much slower rates of exhumation. This variation in

  12. Subduction and exhumation of continental crust: insights from laboratory models (United States)

    Bialas, Robert W.; Funiciello, Francesca; Faccenna, Claudio


    When slivers of continental crust and sediment overlying oceanic lithosphere enter a subduction zone, they may be scraped off at shallow levels, subducted to depths of up to 100-200 km and then exhumed as high pressure (HP) and ultra-high pressure (UHP) rocks, or subducted and recycled in the mantle. To investigate the factors that influence the behaviour of subducting slivers of continental material, we use 3-D dynamically consistent laboratory models. A laboratory analogue of a slab-upper mantle system is set up with two linearly viscous layers of silicone putty and glucose syrup in a tank. A sliver of continental material, also composed of silicone putty, overlies the subducting lithosphere, separated by a syrup detachment. The density of the sliver, viscosity of the detachment, geometry of the subducting system (attached plate versus free ridge) and dimensions of the sliver are varied in 34 experiments. By varying the density of the sliver and viscosity of the detachment, we can reproduce a range of sliver behaviour, including subduction, subduction and exhumation from various depths and offscraping. Sliver subduction and exhumation requires sufficient sliver buoyancy and a detachment that is strong enough to hold the sliver during initial subduction, but weak enough to allow adequate sliver displacement or detachment for exhumation. Changes to the system geometry alter the slab dip, subduction velocity, pattern of mantle flow and amount of rollback. Shallower slab dips with more trench rollback produce a mantle flow pattern that aids exhumation. Steeper slab dips allow more buoyancy force to be directed in the up-dip direction of the plane of the plate, and aide exhumation of subducted slivers. Slower subduction can also aide exhumation, but if slab dip is too steep or subduction too slow, the sliver will subduct to only shallow levels and not exhume. Smaller slivers are most easily subducted and exhumed and influenced by the mantle flow.

  13. Thermochronologic evidence for Miocene mid-crustal tectonic exhumation of the Huachuca Mountains, southeast Arizona (United States)

    King, C. C.; Orme, D. A.; Biswas, A.; Reiners, P. W.


    Zircon double dating of detrital grains from the northward flowing upper San Pedro river valley at Murray Springs in southeastern Arizona yields abundant zircons with variable U/Pb crystallization ages of ~70-1400 Ma, but a restricted range of (U-Th)/He cooling ages of ~18-25 Ma. This combination of diverse formation ages but uniform mid-Miocene cooling ages is characteristic of zircons from the core complexes and deeply exhumed Santa Catalina, Rincon, and Pinaleno Mountains, which experienced tectonic exhumation from mid-crustal depths during mid-Miocene extension. But all these sources are far downstream or outside the watershed of the upper San Pedro valley. To trace the source of these detrital grains and understand the implications for regional tectonics, we also measured U/Pb and (U-Th)/He dates of zircons from the Tombstone Hills and Huachuca Mountains, proximal to the Murray Springs site. Magmatic rocks in the Tombstone Hills yielded U/Pb dates of 76-83 Ma and zircon He ages of 53-60 Ma. In contrast, crystalline basement of the Huachucas yields Cretaceous through 1.5-Ga U/Pb ages and zircon He ages of 17-25 Ma, with most between 21-22 Ma. These data require that a large region of the Huachucas contains rocks that cooled rapidly below temperatures of at least 180 oC in the mid-Miocene. Assuming typical geothermal gradients of 20-30 oC, this requires exhumation of at least 7-9 km of crust, likely within 1-2 Myr. While it is possible that erosion contributed, it is more likely that denudation was accommodated by deep tectonic exhumation. Faults are observed on the basin-bounding east-side of the Huachucas, but most are inferred to accommodate Laramide-age thrusting, and the normal faults have been interpreted as high-angle and unlikely to cause significant tectonic exhumation. Our new data suggest that a large part of the presently exposed Huachucas was exhumed from depths at least as great as ~7-9 km, requiring a considerable revision of structural

  14. New Apatite and Zircon (U-Th)/He Constraints on the Timing of Thrust-Related Exhumation in the Southern Bolivian (21˚S) Andes (United States)

    Anderson, R. B.; Long, S. P.; Horton, B. K.; Calle, A.; Stockli, D. F.


    Data suggesting rapid middle Miocene uplift of the southern Altiplano prompts resolving disagreements over the geometry, magnitude, and timing of Andean deformation in southern Bolivia (21°S) in order to test geodynamic responses of the thrust belt predicted by the Cordilleran cyclicity model. New apatite and zircon (U-Th)/He data combined with published apatite fission track data (AFT), new 1:50:000-scale mapping, and in-progress drafting of a balanced cross-section provide new insight into the geometry and timing of deformation, and the timing and rates of exhumation. Mapping was focused along an east-west transect through the Subandean Zone (SAZ), Interandean Zone (IAZ), and Eastern Cordillera (EC). Regional-scale folds (~10-20 km wavelength, ~4-6 km amplitude) in the SAZ exhume rocks as deep as Carboniferous above a 10-12 km deep decollemont in Silurian rocks. In the IAZ, thinner (~1-4 km), closely-spaced thrust sheets exhume Devonian and Silurian rocks, and a regional-scale anticlinorium in the easternmost EC exhumes rocks as deep as Cambrian and Ordovician. 11 new apatite and 5 new zircon (U-Th)/He cooling ages provide timing constraints on the initiation of thrust-related exhumation. Zircon cooling ages (32.8±1.4 to 25.4±1.2 Ma) reveal initiation of exhumation in the easternmost EC as early as ~32 Ma, and an exhumed partial retention zone at the EC-IAZ boundary. Apatite ages in the IAZ range from 21.71±0.77 to 7.45±0.20 Ma, and consistently young to the east. Exhumation was previously thought to have begun in the IAZ at ~10 Ma, but our results show thrust-related exhumation as early as ~22 Ma, in agreement with published AFT data that show that deformation had propagated eastward into the IAZ by at least ~18 Ma. In the western SAZ, apatite cooling ages of 6.10±0.17 and 4.84±0.14 Ma demonstrate that thrust-related uplift and exhumation in the western SAZ had begun by at least the late Miocene. These new data show a consistent eastward propagation of

  15. Buoyancy-driven flow excursions in fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D. [Westinghouse Savannah River Company, Aiken, SC (United States)


    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating heavy water moderator downward through channels in cylindrical fuel tubes. Powers were limited to safeguard against a flow excursion in one of more of these parallel channels. During-full-power operation, limits safeguarded against a boiling flow excursion. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increased beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of the limiting power for previous long-term reactor operations.

  16. Characteristics of Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Li, Zhigang

    Air flow through horizontal openings is an important issue of mass and energy transfer between different zones in buildings. This kind of mass and energy transfer have important implications regarding energy saving, thermal comfort, control of contaminants, micro-organisms and spread of fire...... and smoke. Air flow through vertical openings has been widely investigated but little is known about the flow in the horizontal openings, especially when they are driven by buoyancy. A literature survey shows that the brine-water system and the scale model are normally used forthe research work of air flow....... Computational fluid dynamics (CFD) are used to study these two air flow cases. The air flow rate and air flow pattern are predicted and compared with the full-scale measurements. The measurement data are used to compare two CFD models: standard k- ε model and large eddy simulation (LES) model. The cases...

  17. Buoyancy-driven flow excursions in fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D.


    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating moderator downward through channels in cylindrical fuel tubes. Powers were limited to prevent a flow excursion from occurring in one or more of these parallel channels. During full-power operation, limits prevented a boiling flow excursion from taking place. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increases beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of historical levels.

  18. Eocene extensional exhumation of basement and arc rocks along southwesternmost Peru, Central Andes. (United States)

    Noury, Mélanie; Bernet, Matthias; Sempéré, Thierry


    The overthickened crust of the current Central Andes is commonly viewed as the result of tectonic shortening. However, in the present-day terrestrial forearc and arc of southwesternmost Peru, crustal thickness increases from 30 km along the coastline to >60 km below the active arc, whereas the upper crust exhibits little to no evidence of crustal shortening and, in constrast, many extensional features. How (and when) crustal overthickness was acquired in this region is thus little understood. Because crustal overthickening often results in extensional collapse and/or significant erosion, here we address this issue through a regional-scale study of exhumation using fission-track thermochronology. The limited fission-track data previously available in the area suggested that exhumation began during the Mesozoic. In this study, we present new apatite and zircon fission-track data obtained along the current terrestrial forearc of southwesternmost Peru. This relatively restricted area presents the interest of providing extensive outcrops of Precambrian to Ordovician basement and Early Jurassic to Late Cretaceous arc plutons. In order to compare the chronology of exhumation of these units, we performed extensive sampling for fission-track dating, as well as structural mapping. Our results indicate that the basement rocks and Jurassic plutons that crop out in the Arequipa region, where the crust is now >50 km-thick, experienced a rapid cooling through the 240-110°C temperature range between ~65 and ~35 Ma. This period of rapid exhumation coincided in time with the accumulation of terrestrial forearc deposits (the Lower Moquegua Group), that exhibit many syn-sedimentary extensional features and are bounded by conspicuous normal faults, specifically along the region where intense activity of the main arc between ~90 and ~60 Ma had led to voluminous magma emplacement. This close succession of (1) intense magmatic activity and (2) regional-scale exhumation associated with

  19. River network evolution as a major control for orogenic exhumation: Case study from the western Tibetan plateau (United States)

    Gourbet, Loraine; Mahéo, Gweltaz; Shuster, David L.; Tripathy-Lang, Alka; Leloup, Philippe Hervé; Paquette, Jean-Louis


    The westernmost Tibetan plateau, despite being internally drained, has a high topographic relief. Here, using apatite (U-Th-Sm)/He and 4He/3He thermochronometry, we reconstruct the exhumation history of the Rutog batholith during the Neogene. Thermal modeling in 1D using the QTQt program indicates that relatively slow cooling occurred from 30 Ma to 19 Ma, which we interpret as an exhumation rate of ∼10 m/Ma. This was followed by two pulses of moderate cooling from 19 to 17 Ma and ∼11 to 9 Ma that correspond to a total exhumation of about 1500 m. Cooling since 9 Ma has been negligible. This differs from exhumation patterns in central Tibet but reveals timing similarities with externally drained portions of southern Tibet. We interpret our cooling constraints as recording two different transitions in western Tibet from an externally to an internally drained system since the Oligocene. External drainage allowed this part of the Tibetan plateau, unlike internally drained portions of central Tibet, to record regional-scale processes. The first cooling event, at about 20 Ma, was likely related to a major geodynamic event such as slab breakoff that induced contemporaneous potassic and ultrapotassic magmatism. The second rapid cooling pulse from ∼11 Ma to 9 Ma and subsequent negligible cooling was most likely controlled by a local factor such as Indus and Shyok river network reorganization caused by dextral motion of the Karakorum fault. We discuss these interpretations and their limitations in this contribution.

  20. A Model of Secondary Hydrocarbon Migration As a Buoyancy-Driven Separate Phase Flow Un modèle de migration secondaire des hydrocarbures considéré comme un écoulement en phases séparées régi par la poussée d'Archimède

    Directory of Open Access Journals (Sweden)

    Lehner F. K.


    Full Text Available A mathematical model of secondary migration is described which permits the prediction of hydrocarbon migration and accumulation patterns in a sedimentary basin, if source rock expulsion rates and geometrical and hydraulic properties of major carrier systems are known through geological time. In this model, secondary migration is treated as buoyancy-driven, segregated flow of hydrocarbons in hydrostatic aquifers. Lateral, updip migration is conceived as a Boussinesq-type, free-surface flow, with source and sink terms representing supply from source rocks and leakage through cap rocks and faults. This permits a two-dimensional, map-view mathematical description of a three-dimensional, time-dependent secondary migration system. A nine-point finite difference approximation has been developed to minimize numerical dispersion, and upstream-weighting is used to obtain stable solutions. Example computations for simple, single carrier bed structures are presented. L'article décrit un modèle mathématique de migration secondaire prédisant la migration des hydrocarbures et leur accumulation dans un bassin sédimentaire, lorsque les taux d'expulsion des roches mères et les propriétés géométriques et hydrauliques des principaux systèmes de drainage sont connus à l'échelle du temps géologique. Dans ce modèle, la migration secondaire est traitée comme un écoulement des hydrocarbures en phase séparée, contrôlé par la poussée d'Archimède, dans des aquifères hydrostatiques. La migration latérale est considérée comme un écoulement de type Boussinesq, à surface libre, avec des termes sources et puits représentant les apports venant des roches mères et les fuites à travers les couvertures et les failles. Ceci permet une description mathématique bidimensionnelle cartographiable d'un système de migration secondaire tridimensionnel et dépendant du temps. On utilise une approximation type différences finies à neuf points pour minimiser

  1. Plio-Pleistocene exhumation of the eastern Himalayan syntaxis and its domal 'pop-up' (United States)

    Bracciali, Laura; Parrish, Randall R.; Najman, Yani; Carter, Andrew; Wijbrans, Jan R.; Smye, Andrew


    The eastern termination of the Himalayan orogen at the southern margin of the Tibetan Plateau forms a syntaxial antiform that folds the suture zone between the Indian and Asian plates and is characterised by 10 to Indian foreland basin before emptying into the Bay of Bengal. Exceptionally high relief and one of the deepest gorges on Earth have developed where the river's tortuous route crosses the Namche Barwa-Gyala Peri massif (> 7 km in elevation) in the core of the syntaxis. Downstream of the gorge very high erosion rates contribute ~ 50% of total detritus to the sediment load of the river. The initiation of the exceptional exhumation has been attributed either to the extreme erosive power of a river flowing across a deforming indentor corner and the positive feedback that would establish between the two, or to subduction geometry of a stiffened indentor corner. It has also been suggested that the growth of the antiformal structure and the exhumation of its high grade metamorphic core resulted from buckling as a means to accommodate shortening in the indentor corner. In this study [1] we provide new chronological data on the bedrock of the eastern syntaxis and its erosion products to date the inception of very rapid uplift and erosion and discuss its cause, with the ultimate aim to reconstruct the structural and exhumation history of the syntaxis. We use U-Pb zircon and rutile, white mica Ar-Ar and fission track zircon dating of bedrock, modern sediments and Neogene paleo-Brahmaputra deposits of the Surma Basin (Bangladesh) to document source rock crystallization and cooling events from > 700°C to ~ 250°C as well as numerical modelling of heat flow and erosion. Based on our and other published data we show that: i) the detrital age signature of the modern syntaxis is unique within the eastern Himalayan region; ii) the rocks within the domal pop-up were >500°C only 1-2 Ma; iii) up to ~20 km of rock were eroded during the Pleistocene from the domal core of the

  2. Progressive Extensional Exhumation of the Ultrahigh-Pressure Tso Morari Terrain, NW Indian Himalaya (United States)

    Hodges, K.; Clark, R.; Monteleone, B.; Sachan, H.; Mukherjee, B. K.; Ahmad, T.


    The core of the Tso Morari dome in the Ladakh region of NW India (roughly 33 °10'N; 78°10'E) is one of only two known ultrahigh-pressure (UHP) terrains in the Himalayan-Tibetan orogenic system. The quartzofeldspathic Puga Orthogneiss from the structurally deepest portions of the terrain does not contain UHP mineralogy but surrounds dismembered lenses of mafic eclogite with accessory coesite, confirming that at least the eclogite lenses experienced UHP metamorphic conditions (Mukherjee et al., 2003, International Geology Review; Sachan et al., 2004, European Journal of Mineralogy). U-Pb zircon dates from the Puga orthogneiss (53.3 ± 0.7 Ma: Leech et al., 2007, International Geology Review) provide what appear to be the most precise available constraints on the age of UHP metamorphism at Tso Morari provided we presume that the UHP assemblages in the eclogite lenses developed at the same time as the 53.3 ± 0.7 Ma metamorphic zircon in the orthogneiss. However, other components of the zircon population studied by Leech and co-workers, as well as the results obtained using other thermochronometers and geochronometers (de Sigoyer et al., 2004, Tectonics), demonstrate that a series of lower pressure metamorphic events also affected the Tso Morari terrain between ca. 53 Ma and ca. 45 Ma, implying rapid decompression at elevated temperatures (ca. 800 - 350°C). Our 1:50000-scale geologic mapping at Tso Morari provides evidence that this exhumation was largely accommodated by two previously unrecognized low-angle ductile detachments that separate the terrain into three tectonostratigraphic units with distinctive metamorphic histories. The structurally lowest shear zone (Karla detachment) separates the Puga Orthogneiss from overlying lower amphibolite facies metasedimentary rocks of the Zoboshisha Unit, which contains no UHP assemblages. Structurally higher and demonstrably younger detachments separate the Zoboshisha Unit and the Puga Orthogneiss from greenschist to

  3. Measuring crustal convergence using rock exhumation along the complex glaciated Chugach Mountains, southeast Alaska (United States)

    Spotila, J. A.; Buscher, J.


    Rates of rock uplift often constrain magnitudes of convergent plate motion in collisional settings. In complex orogenic belts, however, these rates can be difficult to measure. In southeast Alaska, a rapidly-evolving mountain system is centered at a syntaxial bend in the Pacific-North American plate boundary. Rugged topography of the Chugach Mountains stretches for more than 500 km along the hanging wall of the Aleutian Trench, above a colliding microplate, and as coast ranges along the Queen Charlotte-Fairweather transform fault. At each segment of the plate boundary, crustal convergence within North America should vary according to the obliquity of plate motion and the degree of underthrusting. Geodetic and neotectonic studies of rapidly-eroding structures have yet to define rates of horizontal plate motion partitioning. Surface uplift studies, based on short term geodesy or Holocene motion of coastal landforms, are also complicated by megathrust elastic strain accumulation cycles and the viscoelastic response to recent glacial ice thinning. It is thus important to measure exhumation and the erosional transfer of mass as a proxy for the degree of upper crustal convergence accommodated by rock uplift. We have attempted to determine exhumation pattern where the highly-deformed, oceanic and continental rocks of the Yakutat microplate collide with North America. Although the total shortening rate between this microplate and North America is of the order ~3-5 cm/yr, an unconstrained magnitude of shortening is absorbed by imbricate thrust faults within it, the suture between it and North America, and within the previously accreted terranes that form the edge of the continent. We have constrained rock cooling histories as a proxy for exhumation on samples along a dense grid that spans major structural elements, including the Pamplona and Chugach-St. Elias fault systems. Apatite and zircon radiogenic helium ages provide a range in temperature sensitivity that can be used

  4. Spatiotemporal variation in exhumation of the Crystallines in the NW-Himalaya, India: Constraints from fission track dating analysis (United States)

    Patel, R. C.; Adlakha, Vikas; Lal, Nand; Singh, Paramjeet; Kumar, Y.


    During Himalayan orogeny, coeval thrusting along the Main Central/Munsiari Thrust (MCT/MT) and extension along the South Tibetan-Detachment System (STDS) are widely responsible for rapid exhumation of the Higher Himalayan Crystalline (HHC) zone. Apatite and zircon fission-track data along the Kaliganga and Darma valleys in the Kumaon Himalaya serve to document the shallow bedrock exhumation history of the HHC. Taking into account sample location within the HHC with respect to the MCT/MT, the apatite fission track (AFT) data-sets along the Darma (1.0 ± 0.1 to 2.8 ± 0.3 Ma) and Kaliganga (1.4 ± 0.2 to 2.4 ± 0.3 Ma) which are sharing same structural setting and rock types and being separated by 40 km, show very similar patterns of exhumation histories since Plio-Quaternary in the Kumaon Himalaya. Data sets along Darma and Kaliganga are very similar to data set of adjacent traverse (50 km away) along the Goriganga valley studied by Patel and Carter (2009). Whole data sets within the HHC in Kumaon Himalaya provide clear evidence for Plio-Quaternary tectonic activity along the Vaikrita Thrust (VT). Precipitation in this region exerts a strong influence on erosional surface processes. Fluvial erosional unloading along the Himalaya is focused on the high mountainous region of the HHC, where the orographic barrier forces out the maximum percentage of annual rainfall. FT cooling ages reveal coincidence between rapid erosion and exhumation that is focused in a ~ 25-30 km wide sector of the HHC, rather than covering the entire orogen. Similarity of AFT age pattern and exhumation rates along all three major traverses (Goriganga, Darma and Kaliganga) indicates that the region has been experiencing constant rate of crustal uplift and erosion since long time. Comparison of fission track ages from the Kumaon Himalaya with other segments of the NW-Himalaya shows spatiotemporal variation in exhumation. It is described due to the development of local structures such as dome

  5. Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: response to slab dynamics and erosion (United States)

    Carrapa, Barbara; Orme, D.A.; DeCelles, Peter G.; Kapp, Paul; Cosca, Michael A.; Waldrip, R.


    The India-Asia collision zone in southern Tibet preserves a record of geodynamic and erosional processes following intercontinental collision. Apatite fission-track and zircon and apatite (U-Th)/He data from the Oligocene–Miocene Kailas Formation, within the India-Asia collision zone, show a synchronous cooling signal at 17 ± 1 Ma, which is younger than the ca. 26–21 Ma depositional age of the Kailas Formation, constrained by U-Pb and 40Ar/39Ar geochronology, and requires heating (burial) after ca. 21 Ma and subsequent rapid exhumation. Data from the Gangdese batholith underlying the Kailas Formation also indicate Miocene exhumation. The thermal history of the Kailas Formation is consistent with rapid subsidence during a short-lived phase of early Miocene extension followed by uplift and exhumation driven by rollback and northward underthrusting of the Indian plate, respectively. Significant removal of material from the India-Asia collision zone was likely facilitated by efficient incision of the paleo–Indus River and paleo–Yarlung River in response to drainage reorganization and/or intensification of the Asian monsoon.

  6. Pulsed exhumation of interior eastern Tibet: Implications for relief generation mechanisms and the origin of high-elevation planation surfaces (United States)

    Zhang, Huiping; Oskin, Michael E.; Liu-Zeng, Jing; Zhang, Peizhen; Reiners, Peter W.; Xiao, Ping


    River incision into a widespread, upland low-relief landscape, and related patterns of exhumation recorded by low-temperature thermochronology, together underpin geodynamic interpretations for crustal thickening and uplift of the eastern Tibetan Plateau. We report results from a suite of 11 (U-Th-Sm)/He cooling-age samples. Eight samples comprise a 1.2 km relief section collected from elevations up to 4800 m in the Jiulong Shan, an elevated, rugged region located in the hinterland of the Yalong-Longmen Shan Thrust Belt, and surrounded on three sides by upland low-relief landscape surfaces. Zircon and apatite cooling ages record two episodes of rapid exhumation in the early Oligocene and late Miocene, that were separated by a period of stability from ∼30 to 15 Ma. The first episode is consistent with a similar pulse evident from the Longmen Shan. The second episode is ongoing, and when integrated with adjacent cooling-age data sets, shows that doming of the Jiulong Shan has resulted in 2 to 4 km of differential exhumation of the plateau interior. We show from a compilation of glacial landform-mapping that the elevation of the plateau surface closely tracks global last glacial maximum equilibrium line altitude. We hypothesize that smoothing of highlands by efficient glacial and periglacial erosion, coupled with potential river captures and conveyance of sediments via external drainage, can yield an apparently continuous low-relief plateau landscape formed diachronously at high elevation.

  7. Links between tectonism and exhumation in the Spanish Pyrenees: Evidence from apatite fission track analysis and Ar fault dating (United States)

    Rahl, J. M.; Haines, S. H.; van der Pluijm, B. A.


    Analytical, numerical, and mechanical models of orogenic wedges suggest that the structural and erosional evolution of mountain belts are tightly linked. For example, erosion in the core of a mountain belt may thin a wedge and drive out-of-sequence faulting to reestablish critical taper. To provide a field-based test of these ideas, we present new geochronologic constraints on the deformational and erosional history of the orogenic wedge exposed in the south-central Spanish Pyrenees. Apatite fission-track data from the syn-orogenic sediments of the Sierra de Sis conglomerate reveal generally invariant ages in strata deposited between about 42 and 27 Ma. These data, as well as track-length distributions indicative of rapid cooling, imply the bedrock in the core of the wedge that produced the sediment experienced fast exhumation that began by at least 48 Ma and continued until 42 Ma. Numerical modeling of the detrital data suggests the source region experienced a deceleration in erosion rate from about 1.0 mm/yr to less than 0.5 to 0.2 mm/yr. Published bedrock thermochronometric data collected from the interior of the belt indicate a renewed period of rapid erosional exhumation culminating around 32 Ma. The temporal changes in erosion recorded by thermochronology are correlated with the deformational history of the Pyrenean fold-thrust belt. We present new constraints on fault activity in the Pyrenean foreland through the direct dating of fault gouge by illite age analysis. New fault dates show that tectonic activity youngs towards the interior of the mountain belt, with fault slip correlating to periods of rapid erosion. The relatively outboard Boixols fault has an age of 71 ± 6.4 Ma, reflecting Cretaceous convergence that marks the onset of Pyrenean deformation. Slip on the more inboard Nogueres fault occurred later, at 56 ± 1.4 Ma, consistent with a period of rapid erosion that continued through about 45 Ma inferred from detrital fission-track data. After a long

  8. Fluid activity during exhumation of deep-subducted continental plate

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yongfei


    It is well known that a great deal of fluid was released during subduction of oceanic crust, resulting in arc magmatism, quartz veining and metamorphic mineralization of syn-subduction. In contrast, the process of continental subduction is characterized by the relative lack of fluid and thus no arc magmatism has been found so far. During exhumation of deep-subducted continental crust, nevertheless,significant amounts of aqueous fluid became available from the decomposition of hydrous minerals, the decrepitation of primary fluid inclusions, and the exsolution of structural hydroxyls. This kind of metamorphic fluid has recently attracted widespread interests and thus been one of the most important targets in deciphering the geological processes concerning metamorphism, magmatism and mineralization in collisional orogens. A large number of studies involving stable isotopes, fluid inclusions and petrological phase relationships have been accomplished in past a few years with respect to the mobility and amount of metamorphic fluid in UHP metamorphic rocks from the Dabie-Sulu orogenic belt.The results demonstrate that the fluid activity during the exhumation of deep-subducted continental crust has the following effects: (1) amphibolite-facies retrogression due to pervasive fluid flow; (2) formation of HP quartz veins within eclogites due to channelized fluid flow; and (3) partial melting of overlying crustal rocks due to focused fluid flow, producing syn-exhumation magmatism within the orogenic belt.In particular, the aqueous fluid released by decompression exsolution of hydroxyl from UHP minerals is characterized by low salinity and is capable of resulting in pervasive and channellized flow. Therefore, the intensive study of fluid activity during exhumation of UHP metamorphic rocks can not only provide insight into geodynamic processes that occurred in continental collisional belts, but also shed light on understanding of crust-mantle recycling and relevant magmatism in

  9. Magmatism as a response to exhumation of the Priest River complex, northern Idaho: Constraints from zircon U-Pb geochronology and Hf isotopes (United States)

    Stevens, L. M.; Baldwin, J. A.; Crowley, J. L.; Fisher, C. M.; Vervoort, J. D.


    Zircon and monazite U-Pb geochronology and zircon Hf isotopes place constraints on the temporal and source relationships between crustal anatexis, magmatism, and exhumation of the Priest River metamorphic core complex, northern Idaho. Granitoids that intruded the migmatitic, pelitic Hauser Lake gneiss include the pluton emplacement in the Priest River complex indicates that it was primarily a response to decompression rather than a cause. The mylonitized Silver Point and undeformed Wrencoe plutons bracket the end of a rapid phase of exhumation to c. 50-48 Ma. Zircon εHf(i) values and Lu-Hf isotope evolution indicate that the Silver Point and Wrencoe plutons crystallized from homogeneous magmas sourced from Archean-Proterozoic basement orthogneisses, whereas the Spokane granite and two leucocratic units appear to have been produced by partial melting of the Hauser Lake gneiss. Comparison of the Priest River complex with other deeply exhumed northern Cordilleran complexes indicates variability in the timing and, therefore, relative influences of partial melting and magmatism on the initiation of exhumation, which must be accounted for in numerical models of metamorphic core complex formation and evolution.

  10. Cretaceous–Cenozoic burial and exhumation history of the Chukchi shelf, offshore Arctic Alaska (United States)

    Craddock, William H.; Houseknecht, David W.


    Apatite fission track (AFT) and vitrinite reflectance data from five exploration wells and three seafloor cores illuminate the thermal history of the underexplored United States Chukchi shelf. On the northeastern shelf, Triassic strata in the Chevron 1 Diamond well record apatite annealing followed by cooling, possibly during the Triassic to Middle Jurassic, which is a thermal history likely related to Canada Basin rifting. Jurassic strata exhumed in the hanging wall of the frontal Herald Arch thrust fault record a history of probable Late Jurassic to Early Cretaceous structural burial in the Chukotka fold and thrust belt, followed by rapid exhumation to near-surface temperatures at 104 ± 30 Ma. This history of contractional tectonism is in good agreement with inherited fission track ages in low-thermal-maturity, Cretaceous–Cenozoic strata in the Chukchi foreland, providing complementary evidence for the timing of exhumation and suggesting a source-to-sink relationship. In the central Chukchi foreland, inverse modeling of reset AFT samples from the Shell 1 Klondike and Shell 1 Crackerjack wells reveals several tens of degrees of cooling from maximum paleo-temperatures, with maximum heating permissible at any time from about 100 to 50 Ma, and cooling persisting to as recent as 30 Ma. Similar histories are compatible with partially reset AFT samples from other Chukchi wells (Shell 1 Popcorn, Shell 1 Burger, and Chevron 1 Diamond) and are probable in light of regional geologic evidence. Given geologic context provided by regional seismic reflection data, we interpret these inverse models to reveal a Late Cretaceous episode of cyclical burial and erosion across the central Chukchi shelf, possibly partially overprinted by Cenozoic cooling related to decreasing surface temperatures. Regionally, we interpret this kinematic history to be reflective of moderate, transpressional deformation of the Chukchi shelf during the final phases of contractional tectonism in the

  11. An exhumed Late Paleozoic canyon in the rocky mountains (United States)

    Soreghan, G.S.; Sweet, D.E.; Marra, K.R.; Eble, C.F.; Soreghan, M.J.; Elmore, R.D.; Kaplan, S.A.; Blum, M.D.


    Landscapes are thought to be youthful, particularly those of active orogenic belts. Unaweep Canyon in the Colorado Rocky Mountains, a large gorge drained by two opposite-flowing creeks, is an exception. Its origin has long been enigmatic, but new data indicate that it is an exhumed late Paleozoic landform. Its survival within a region of profound late Paleozoic orogenesis demands a reassessment of tectonic models for the Ancestral Rocky Mountains, and its form and genesis have significant implications for understanding late Paleozoic equatorial climate. This discovery highlights the utility of paleogeomorphology as a tectonic and climatic indicator. ?? 2007 by The University of Chicago. All rights reserved.

  12. Cenozoic evolution of the Yakutat-North American collision zone and structural accommodation of St. Elias syntaxis exhumation, Alaska/Yukon (United States)

    Falkowski, Sarah; Enkelmann, Eva; Ehlers, Todd


    Active convergent margins potentially pose multiple natural hazards to human life and infrastructure. Tectonic strain may be further focused where convergent margins are warped into broad syntaxes. However, the processes responsible for upper plate deformation in these settings are not well understood. The St. Elias syntaxis in southeast Alaska and southwest Yukon is located at the eastern corner of the Yakutat microplate, which indents into the North American Plate and subducts at a flat angle beneath Alaska. High rates of long-term glacial erosion and exhumation (>2 mm/yr) are found on the southern, coastal flanks of the St. Elias orogen, but the deepest and most rapid exhumation is focused at the St. Elias syntaxis. In this location, transform motion transitions into subduction of the wedge-shaped, oceanic plateau of the Yakutat microplate. In order to map the spatio-temporal pattern of exhumation in the Yakutat-North American collision zone, we conducted zircon and apatite fission-track analyses of predominantly detrital, sand-sized material and five bedrock samples from 47 different glacio-fluvial catchments covering an area of ~45,000 km2 around the St. Elias syntaxis. Integration of the new thermochronologic data with prior work and other geologic and geophysical observations yielded information on past terrane accretion events at the North American margin since the late Mesozoic and the evolution of exhumation at the St. Elias syntaxis in the context of the ongoing Yakutat-North American plate collision. Our results indicate a migrating focus of the most rapid exhumation from north to south and from the upper (North American Plate) to the lower (Yakutat microplate) plate in the syntaxis area over the past ~10 Myr. This migration occurred in response to a change in plate motions, increasingly thicker crust of the subducting Yakutat microplate, and changes in surface processes after glaciation began that resulted in modification of the rheology. We propose a

  13. How Orogen-scale Exhumed Strike-slip Faults Initiate (United States)

    Cao, S.; Neubauer, F.


    Orogen-scale strike-slip faults present one the most important geodynamic processes affecting the lithosphere-asthenosphere system. In specific subtypes, faulting is virtually initiated along hot-to-cool boundaries, e.g. at such of hot granite intrusions or metamorphic core complexes to cool country rocks. Such fault zones are often subparallel to mountain ranges and expose a wide variety of mylonitic, cataclastic and non-cohesive fault rocks, which were formed at different structural levels of the crust and are stacked within each other ("telescoping"). Exhumation of rocks is, therefore, a common feature of such strike-slip faults implying major transtensive and/or transpressive processes accompanying pure strike-slip motion. The hot-to-cool thermal structure across the fault zone significantly influences the physical fault rock properties. One major question is how and where a major strike-slip initiates and further development. Here, we propose a model in which major continental exhumed strike-slip faults potentially evolve along rheologically weak zones such as plutons or margins of metamorphic complexes. As an example, we propose a model for the Ailao Shan-Red River (ASRR) fault, SE Asia, which initiated along the edge of a plutonic belt and evolved in response to India-Asia collision with four tectonic phases.

  14. White mica K-Ar geochronology of HP-UHP units in the Lago di Cignana area, western Alps, Italy: Tectonic implications for exhumation (United States)

    Gouzu, Chitaro; Yagi, Koshi; Thanh, Ngo Xuan; Itaya, Tetsumaru; Compagnoni, Roberto


    High-pressure and ultra-high pressure (HP-UHP) blueschist- and eclogite-facies metabasaltic and metasedimentary rocks occur in four different tectonic units near Lago di Cignana, western Alps. We have determined K-Ar ages for white micas (matrix phengite and paragonite) from the Lago di Cignana UHP unit (LCU; 39-41 Ma); the lower and upper units of the Zermatt-Saas meta-ophiolite (LU and UU; 37-38 Ma and 38-41 Ma respectively), and the Combin unit (CU; 36-40 Ma). These K-Ar ages overlap with single-grain Ar-Ar plateau ages (36-42 Ma) previously determined for phengites from LCU metasediments. Matrix white micas have been severely deformed during exhumation, and their chemistries differ from those of micas included in garnet. Although individual mica grains in the matrix could have experienced different degrees of deformation which have reset their K-Ar systems, "bulk" white mica separates provide the average age of all the individual grains in the separate. The similarity of ages determined for white micas from the LCU, LU, UU and CU units, regardless of rock type and mineral species, suggests that these four units were metamorphosed together as part of a single metamorphic sequence in the Piemonte-Liguria paleosubduction zone and were subsequently exhumed together. However, present-day structural relationship among those units and the limited occurrence of UHP minerals in LCU suggests that the exhumation of LCU was more rapid than that for LU, UU and CU. The age gaps between the youngest value of white mica K-Ar ages in each unit and the inferred timing of the metamorphic peak (U-Pb age: 44 Ma) is 5, 7, 6 and 8 Myr for LCU, LU, UU and CU, respectively. These intervals are considerably shorter than that determined for the Sanbagawa HP metamorphic belt of Southwest Japan (> 31 Myr). The short interval observed for the Lago di Cignana units that we have studied is consistent with the model of rapid exhumation of the UHP-bearing metamorphic domain, suggesting the

  15. Post-emplacement kinematics and exhumation history of the Almora klippe of the Kumaun-Garhwal Himalaya, NW India: revealed by fission track thermochronology (United States)

    Singh, Paramjeet; Patel, R. C.


    Tectonically transported crystalline thrust sheet over the Lesser Himalayan meta-sedimentary zone along the Main Central Thrust (MCT) is represented by Almora, Baijnath, Askot and Chiplakot crystalline klippen. The Almora-Dadeldhura klippe in the Kumaun-Garhwal and western Nepal Himalaya is the witness and largest representative of these crystalline klippen, south of MCT. Here, we investigate the post-emplacement kinematics and exhumation history of the Almora klippe. The newly derived zircon fission track (ZFT) ages combined with published apatite fission track (AFT), 40Ar-39Ar ages from the Almora-Dadeldhura klippe and Ramgarh thrust sheet to quantify the temporal variation in cooling ages and exhumation rates. Using 1-D numerical modelling approach, we calculate the transient exhumation rates with respect to different time intervals. New ZFT cooling ages along 50-km-long orogeny perpendicular transect across the Almora klippe range between 13.4 ± 0.6 and 21.4 ± 0.9 Ma. Published AFT ages and 40Ar-39Ar ages from the Almora-Dadeldhura klippe range 3.7 ± 0.8-13.2 ± 2.7 and 18.20-25.69 Ma, respectively. AFT ages reported from Ramgarh thrust sheet range 6.3 ± 0.8-7.2 ± 1.0 Ma in Kumaun region and 10.3 ± 0.5-14.4 ± 2.2 Ma in western Nepal. The linear age trend along with youngest ZFT age ( 14 Ma) close to the North Almora Thrust (NAT) in its hanging wall suggests rapid uplift close to the NAT due to its reactivation as back thrust. The transient exhumation rates of Almora klippe agree that the erosion rate was rapid (0.58 mma-1) close to the NAT in its hanging wall and relatively slow (0.31 mma-1) close to the SAT in its hanging wall during 15-11 Ma. We interpret that the fission track ages and transient exhumation rate pattern of crystalline klippen show a dynamic coupling between tectonic and erosion processes in the Kumaun-Garhwal Himalaya. However, the tectonic processes play the major role in controlling the exhumation pattern.

  16. Early Cenozoic "dome like" exhumation around the Irish Sea (United States)

    Doepke, Daniel; Cogné, Nathan; Chew, David; Stuart, Fin


    Despite decades of research the Early Cenozoic exhumation history of Ireland and Britain is still poorly understood and subject to contentious debate (see Davis et al., 2012 and subsequent comments). Previous studies have attributed the Cenozoic exhumation history of Ireland and Britain mainly to: (a) Paleogene - Neogene far-field stress between the opening of the North Atlantic Ocean and the Alpine collision (Ziegler et al., 1995; Hillis et al., 2008) or (b) early Paleogene mantle driven magmatic underplating associated with the development of the proto-Iceland mantle plume beneath the Irish Sea (Brodie and White, 1994; Al-Kindi et al., 2003). The major differences between the two hypotheses are the pattern and timing of spatial exhumation. This project thus seeks to investigate the timing and mechanisms of late Mesozoic - early Cenozoic exhumation on the onshore part of the British Isles by using a combination of apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) data, which we then model using the QTQt program of Gallagher (2012) to better constrain the modelled thermal histories. Our studied area centres on the margins of the Irish Sea, but includes all Ireland and western Britain. Overall we analysed 74 samples for AFT and 66 samples for AHe dating. In particular, our results include ten pseudo-vertical profiles. The AFT ages display a wide range of ages from early Carboniferous in Scotland to early Eocene in central Ireland. Our AHe ages range from mid Permian on Shetland to Eocene Ft-corrected. The AFT data do not show any specific spatial distribution, however, the Ft-corrected AHe ages around the Irish Sea only focus around late Cretaceous to Eocene suggesting an important thermal event around this time. The modelled thermal histories of samples located around the Irish Sea and western Scotland show a clear late Cretaceous to early Paleogene cooling event which is not present elsewhere. The distribution of this cooling event is broadly consistent

  17. Large along-strike variations in the onset of Subandean exhumation: Implications for Central Andean orogenic growth (United States)

    Lease, Richard O.; Ehlers, Todd A.; Enkelmann, Eva


    Plate tectonics drives mountain building in general, but the space-time pattern and style of deformation is influenced by how climate, geodynamics, and basement structure modify the orogenic wedge. Growth of the Subandean thrust belt, which lies at the boundary between the arid, high-elevation Central Andean Plateau and its humid, low-elevation eastern foreland, figures prominently into debates of orogenic wedge evolution. We integrate new apatite and zircon (U-Th)/He thermochronometer data with previously published apatite fission-track data from samples collected along four Subandean structural cross-sections in Bolivia between 15° and 20°S. We interpret cooling ages vs. structural depth to indicate the onset of Subandean exhumation and signify the forward propagation of deformation. We find that Subandean growth is diachronous south (11 ± 3 Ma) vs. north (6 ± 2 Ma) of the Bolivian orocline and that Subandean exhumation magnitudes vary by more than a factor of two. Similar north-south contrasts are present in foreland deposition, hinterland erosion, and paleoclimate; these observations both corroborate diachronous orogenic growth and illuminate potential propagation mechanisms. Of particular interest is an abrupt shift to cooler, more arid conditions in the Altiplano hinterland that is diachronous in southern Bolivia (16-13 Ma) vs. northern Bolivia (10-7 Ma) and precedes the timing of Subandean propagation in each region. Others have interpreted the paleoclimate shift to reflect either rapid surface uplift due to lithosphere removal or an abrupt change in climate dynamics once orographic threshold elevations were exceeded. These mechanisms are not mutually exclusive and both would drive forward propagation of the orogenic wedge by augmenting the hinterland backstop, either through surface uplift or spatially variable erosion. In summary, we suggest that diachronous Subandean exhumation was driven by piecemeal hinterland uplift, orography, and the outward

  18. Surface wave tomography of D'Entrecasteaux Islands, Papua New Guinea, implication of mantle control on localization of extension and exhumation (United States)

    Jin, G.; Gaherty, J. B.; Abers, G. A.; Kim, Y.; Eilon, Z.; Buck, W. R.; Verave, R.


    The Woodlark rift system is propagating westward into the Australian plate near Papua New Guinea. The current tip is located east of the D'Entrecasteaux Islands (DEI), where very young ultra-high pressure rocks found within metamorphic core complexes suggest rapid exhumation from ~100km depth in 5%) at shallow depth (Moho to 60km) west of the region of recent extension and exhumation (DEI), while underneath the DEI, the slow anomaly appears to be much deeper (>60km). The shallow low-velocity body in the west roughly parallels both the Trobriand Trench and the Mesozoic-era Australia-Pacific collision zone, and also lies between the current rift tip and the dominant Euler pole (6-0.5Ma) of Woodlark-Australia plate rotation. It may reflect relatively high mantle temperatures beneath the modern (<10Ma) volcanic system that includes Mt. Victory and Mt. Lamington, both of which erupted during the last century. This existing volcanic system may produce a weak zone that helps to localize the extension. As a result, the westward propagation of the Woodlark rift follows and tears apart this volcanic system, and the extension environment enables rapid exhumation driven by buoyant, partially molten upper mantle, as predicted by the diapir model. The deeper low-velocity body underneath the DEI can be explained by rift-system-induced mantle upwelling.

  19. Thermal evolution and exhumation of deep-level batholithic exposures, southernmost Sierra Nevada, California (United States)

    Saleeby, J.; Farley, K.A.; Kistler, R.W.; Fleck, R.J.


    -confidence thermochronometric data track a single retrogressing path commencing from widely established solidus conditions at ca. 100 Ma, and traversing through time-temperature space as follows: (1) Sm/Nd garnet ???770-680 ??C at ca. 102-95 Ma, (2) U/Pb titanite ???750-600 ??C at ca. 102-95 Ma, (3) Ar/Ar hornblende ???570-490 ??C at ca. 94-91 Ma, (4) Rb/Sr biotite ???390-260 ??C at ca. 90-86 Ma, (5) Ar/Ar biotite ???320-240 ??C at ca. 88-85 Ma, and (6) (U-Th)/He zircon ???230-170 ??C at ca. 88-83 Ma. Additional stratigraphic constraints place the complex at surface conditions in Paleocene-early Eocene time (ca. 66-55 Ma). Integration of these results with thermobarometric and structural data, including published data on the underlying Rand Schist, reveals a profound tectonic event whereby rapid cooling and exhumation at rates potentially as high as 100s ??C/m.y. and >5 mm/yr initiated at ca. 98 Ma and peaked between 96 and 94 Ma. Between 93 and 85 Ma, cooling rates remained high, but decelerated with or without significant exhumation. Subsequent cooling and exhumation rates are poorly constrained but were much slower and ultimately resulted in Paleocene-Eocene surface exposure. Initial rapid exhumation and cooling are hypothesized to have been driven by abrupt flattening in the corresponding segment of the Farallon plate and the resulting tectonic erosion of the underlying mantle lithosphere. Protolith as well as meta-morphic pressure-temperature and age constraints on the Rand Schist indicate its rapid low-angle subduction between 93 and 88 Ma. Comparison of the Rand Schist and Tehachapi complex pressure-temperature-time paths in conjunction with structural relations strongly suggest that the schist ascended the equivalent of ???4 kbar relative to the Tehachapi complex by low-angle normal displacement along the Rand fault between 88 and 80 Ma to attain its current underplated structural position. Such extensional tectonism is hypothesized to have been driven by slab rollback

  20. Structural and Thermochronological Constraints on the Coupling Between Exhumation, Denudation and Tectonics in the Himalaya: Insights From the Ama Drime Massif, Tibet- Nepal (United States)

    Jessup, M. J.; Cottle, J. M.; Newell, D. L.; Berger, A. L.; Spotila, J. A.


    Focused denudation and mid-crustal flow are coupled in many active tectonic settings, including the Himalaya where exhumation of mid-crustal rocks is accommodated by thrust faults and low-angle detachment systems during crustal shortening. New structural data demonstrates that the most recently active tectonic feature in the Mt. Everest region is the Ama Drime Massif (ADM), a trans-Himalayan antiformal structure that protrudes ~ 70 km north from the crest of the Himalaya and displaces the South Tibetan Detachment system. Previous investigations interpreted the N-S striking shear zones and fault systems that bound either side of the ADM as the Main Central thrust. Our data show that these are 100-300 m thick normal-sense shear zones that are kinematically linked to young brittle faults that offset Quaternary deposits and record active E-W extension. Geochemical tracers in hot springs along the western shear zone indicate devolatilization of crustal rocks suggesting active metamorphism and/or melting beneath the ADM. Integration of high-to low-T thermochronometric methods, including U(-Th-)Pb, Apatite Fission Track and (U-Th)/He, yield important information regarding the timing and rate of exhumation of the ADM. These data reveal that rapid exhumation of material from the mid-crust during E-W extension began in the mid-Miocene and that a high rate of uplift / denudation persisted into the Pliocene. The southern end of the ADM is centered on the Arun River gorge, which previous geomorphological instigations defined as a prime candidate for climate-tectonic coupling. We combine our results with these exiting data to propose that active exhumation of deep crustal rocks of the ADM during E-W extension is coupled with denudation in the Arun River gorge. This model provides important quantitative constraints on the dynamic feedbacks between climate and tectonics in collisional orogens as well as the evolution of trans-Himalayan rivers and antiformal structures.

  1. Unraveling tectonics and climate forcing in the late-Neogene exhumation history of South Alaska (United States)

    Valla, Pierre; Champagnac, Jean-Daniel; Shuster, David; Herman, Frédéric; Giuditta Fellin, Maria


    The southern Alaska range presents an ideal setting to study the complex interactions between tectonics, climate and surface processes in landscape evolution. It exhibits active tectonics with the ongoing subduction/collision between Pacific and North America, and major active seismogenic reverse and strike-slip faults. The alpine landscape, rugged topography and the important ice-coverage at present reveal a strong glacial imprint associated with high erosion and sediment transport rates. Therefore, the relative importance of climatically-driven glacial erosion and tectonics for the observed late-exhumation history appears to be quite complex to decipher. Here, we first perform a formal inversion of an extensive bedrock thermochronological dataset from the literature to quantify the large-scale 20-Myr exhumation history over the entire southern Alaska. We show that almost half of the variability within the thermochronological record can be explained by modern annual precipitations spatial distribution, the residuals clearly evidencing localized exhumation along major tectonic structures of the frontal fold and thrust belt. Our results confirm high exhumation rates in the St Elias "syntaxis" and frontal zones for the last 0-2 Myr, where major ice fields and high precipitation rates likely sustained high exhumation rates; however the impact of late Cenozoic glaciations is difficult to constrain because of the low resolution on the exhumation history older than ~2 Myr. On the contrary, our inversion outcomes highlight that north of the Bagley Icefield the long-term exhumation has remained quite slow and continuous over the last ~20 Myr, with no late-stage signal of exhumation change since the onset of glaciations despite a clear glacial imprint on the landscape. We thus focus on the Granite Range (Wrangell-St Elias National Park, Alaska), an area presenting a strong glacial imprint but minor tectonic activity with only localized brittle deformation. We sampled four

  2. 40Ar/39Ar geochronology and exhumation of mylonitized metamorphic complex in Changle-Nanao ductile shear zone

    Institute of Scientific and Technical Information of China (English)

    王志洪; 卢华复


    New 40Ar/39Ar plateau ages from rocks of Changle-Nanao ductile shear zone are 107.9 Ma(Mus), 108.2 Ma(Bi), 107. 1 Ma(Bi), 109. 2 Ma(Hb) and 117. 9 Ma(Bi) respectively, which are concordant with their isochron ages and record the formation age of the ductile shear zone. The similarity and apparent overlap of the cooling ages with respective closure temperatures of 5 minerals document initial rapid uplift during 107-118 Ma following the collision between the Min-Tai microcontinent and the Min-Zhe Mesozoic volcanic arc. The 40Ar/39Ar plateau ages, K-Ar date of K-feldspar and other geochronologic information suggest that the exhumation rate of the ductile shear zone is about 0.18-1.12 mm/a in the range of 107-70 Ma, which is mainly influenced by tectonic extension.

  3. Origin and structure of major orogen-scale exhumed strike-slip (United States)

    Cao, Shuyun; Neubauer, Franz


    The formation of major exhumed strike-slip faults represents one of the most important dynamic processes affecting the evolution of the Earth's lithosphere and surface. Detailed models of the potential initiation and properties and architecture of orogen-scale exhumed strike-slip faults and how these relate to exhumation are rare. In this study, we deal with key properties controlling the development of major exhumed strike-slip fault systems, which are equivalent to the deep crustal sections of active across fault zones. We also propose two dominant processes for the initiation of orogen-scale exhumed strike-slip faults: (1) pluton-controlled and (2) metamorphic core complex-controlled strike-slip faults. In these tectonic settings, the initiation of faults occurs by rheological weakening along hot-to-cool contacts and guides the overall displacement and ultimate exhumation. These processes result in a specific thermal and structural architecture of such faults. These types of strike-slip dominated fault zones are often subparallel to mountain ranges and expose a wide variety of mylonitic, cataclastic and non-cohesive fault rocks, which were formed at different structural levels of the crust during various stages of faulting. The high variety of distinctive fault rocks is a potential evidence for recognition of these types of strike-slip faults. Exhumation of mylonitic rocks is, therefore, a common feature of such reverse oblique-slip strike-slip faults, implying major transtensive and/or transpressive processes accompanying pure strike-slip motion during exhumation. Some orogen-scale strike-slip faults nucleate and initiate along rheologically weak zones, e.g. at granite intrusions, zones of low-strength minerals, thermally weakened crust due to ascending fluids, and lateral borders of hot metamorphic core complexes. A further mechanism is the juxtaposition of mechanically strong mantle lithosphere to hot asthenosphere in continental transform faults (e.g., San

  4. Three Dimensional (U-Th)/He Constraints on the Exhumation History of the Shawave- Nightingale Horst Block, Northwestern Nevada (United States)

    Hall, B.; Weinert, A.; Whitehill, C. S.


    We present data from the northwestern Basin and Range Province that provide constraints on the along-strike variation in slip distribution on the Granite Springs Valley fault as well as three-dimensional constraints on the exhumation history of the Shawave-Nightingale horst block. Through the application of coupled apatite-fission track (AFT) and apatite (U-Th)/He (AHe) thermo-chronometry we have determined that an episode of rapid slip (6- 8km) on the fault and exhumation of the granitic block occurred between ~13-8Ma. Combined with data from a more southerly transect and through morphometric observations of the general topographic expression of the range, we are able to delimit that the greatest amount of slip on the fault is coincident with the Juniper Peak transect in the central Shawave Range. The overall distribution on the fault is highest near this central part of the range and is distributed asymmetrically along strike with less relief in the southern termination of the fault and the least exhumation at the very northern termination of the fault. Recent paleo-seismic investigations of the Granite Springs Valley fault document a minimum of two Holocene slip events of ~2-3m along the entire (~60km) length of the range front fault that occurred simultaneously along fault strike. These data are exciting because this is the first three-dimensional application of thermo-chronology to the problem of Basin and Range fault propagation and slip history. Our geologic data support an asymmetric slip history that is in contrast to well-documented simultaneous Quaternay rupture and implies that the fault grew asymmetrically as typically modeled for the normal fault growth but at some point in time, or at some critical fault length, the entire system of range front faults was connected and now currently slips at a constant rate along the length of the range. This holds strong implications for considering geologic vs. geodetic strain rates and for delineating seismic

  5. Structural Geology and Exhumation of the Paleogene Southern Sivas Fold and Thrust Belt, Central Anatolia, Turkey (United States)

    Darin, M. H.; Umhoefer, P. J.; Lefebvre, C.; Thomson, S. N.


    The Anatolian plate (Turkey) was formed during the late Miocene-Pliocene transition from contractional strain in central and eastern Anatolia (collision) to localized strike-slip faulting along inherited collisional structures (escape tectonics). Structural inheritance undoubtedly played a role in this major plate boundary reorganization, although its significance is not well understood. Considerable uncertainty also exists regarding the timing and kinematics of Tauride-Eurasia collision, initial Arabia-Eurasia collision, and the terminal closure of the Neotethys Ocean. The Sivas Basin is a ~E-W-elongate collisional forearc basin located between the Tauride micro-continent in the south and the Pontide Arc along the southern Eurasian margin in the north. Well-exposed contractional structures in Paleocene-Eocene marine strata of the Southern Sivas fold and thrust belt (SSFTB) provide an excellent opportunity to investigate the timing and kinematics of both Tauride and Arabian collisions and their potential roles in localizing strain and facilitating tectonic escape. We use detailed geologic mapping, structural analysis and detrital geo/thermochronology to investigate the magnitude, style, and timing of collision-related crustal shortening across the SSFTB. The structural geology of the SSFTB is characterized by ENE- to ESE-trending, gently plunging fault propagation folds with slight asymmetry towards the north. Vergence on thrust faults is mainly towards the north, although a few previously unmapped faults are south-vergent. Detrital apatite fission track data from Paleocene-Eocene strata reveal a single phase of rapid exhumation ca. ~36-31 Ma, which may be related to either Tauride or initial Arabian collision. We propose that structural growth of the SSFTB at this time played a major role in marine basin isolation and early Oligocene evaporite deposition. In the central and northern Sivas Basin where salt was likely thickest, salt tectonics was initiated by

  6. Mycoflora in Exhumed Seeds of Opuntia tomentosa and Its Possible Role in Seed Germination

    Directory of Open Access Journals (Sweden)

    María Esther Sánchez-Coronado


    Full Text Available The funicular cover of the Opuntia tomentosa seed limits imbibition; germination occurs only when the funicle is weakened or the funicular valve is removed. We investigated the role of fungi in funicular weakening and seed germination. Seeds that had been either buried in one of two sites or stored in the laboratory were germinated with and without a valve. Disinfected or nondisinfected seeds and their naked embryos were cultivated on agar or PDA. None of the 11 identified fungal genera grew on the disinfected control seeds or the embryos. The mycoflora present on disinfected and nondisinfected exhumed seeds suggest that the fungal colonization occurred in the soil and differed between the burial sites. Exhumed seeds with and without a valve germinated in high percentages, whereas only the control seeds without a valve germinated. Scanning electron micrographs showed that the hyphae penetrated, cracked, and eroded the funicular envelope of exhumed seeds.

  7. Significance of "stretched" mineral inclusions for reconstructing P- T exhumation history (United States)

    Ashley, Kyle T.; Darling, Robert S.; Bodnar, Robert J.; Law, Richard D.


    Analysis of mineral inclusions in chemically and physically resistant hosts has proven to be valuable for reconstructing the P- T exhumation history of high-grade metamorphic rocks. The occurrence of cristobalite-bearing inclusions in garnets from Gore Mountain, New York, is unexpected because the peak metamorphic conditions reached are well removed (>600 °C too cold) from the stability field of this low-density silica polymorph that typically forms in high temperature volcanic environments. A previous study of samples from this area interpreted polymineralic inclusions consisting of cristobalite, albite and ilmenite as representing crystallized droplets of melt generated during a garnet-in reaction, followed by water loss from the inclusion to explain the reduction in inclusion pressure that drove the transformation of quartz to cristobalite. However, the recent discovery of monomineralic inclusions of cristobalite from the nearby Hooper Mine cannot be explained by this process. For these inclusions, we propose that the volume response to pressure and temperature changes during exhumation to Earth's surface resulted in large tensile stresses within the silica phase that would be sufficient to cause transformation to the low-density (low-pressure) form. Elastic modeling of other common inclusion-host systems suggests that this quartz-to-cristobalite example may not be a unique case. The aluminosilicate polymorph kyanite also has the capacity to retain tensile stresses if exhumed to Earth's surface after being trapped as an inclusion in plagioclase at P- T conditions within the kyanite stability field, with the stresses developed during exhumation sufficient to produce a transformation to andalusite. These results highlight the elastic environment that may arise during exhumation and provide a potential explanation of observed inclusions whose stability fields are well removed from P- T paths followed during exhumation.

  8. Exhumation history of the southern Altiplano plateau (southern Bolivia) constrained by apatite fission track thermochronology (United States)

    Ege, H.; Sobel, E. R.; Scheuber, E.; Jacobshagen, V.


    Although the structural geometry of the Cenozoic Altiplano-Puna plateau in the central Andes is well defined, the temporal evolution of this contractile deformation is poorly constrained. To address this shortcoming, we used apatite fission track thermochronology (AFT) to quantify the cooling and exhumation history along a transect at 21°S in southern Bolivia, through the deformed intermontane Altiplano basin, the doubly vergent thrust belt of the Eastern Cordillera and the inner foreland thrust belt east of the plateau (Interandean Zone). Thermal history modeling combined with published balanced cross sections and stratigraphic data constrain exhumation histories. Exhumation started during the late Eocene (40-36 Ma) in the central Eastern Cordillera, possibly due to bivergent thrusting and Cretaceous rift structure inversion. During the early Oligocene (33-27 Ma), exhumation spread across the study area as the current boundary thrusts of the Eastern Cordillera were activated. The inner west vergent thrust system became active in irregular order until circa 20 Ma, whereas the east vergent Interandean thrust belt formed by eastward propagating deformation since circa 30 Ma. Plateau exhumation continued at ˜0.2 mm/yr until shortening terminated by 11-7 Ma. Shortening within the plateau since circa 30 Ma did not evolve by lateral accretion of thrust wedges; the propagating deformation style is spatially confined to the foreland thrust belt, which initiated coeval to plateau deformation (Interandean Zone) but propagated mainly after circa 10 Ma (Subandean Zone). Early Oligocene plateau-wide tectonically driven exhumation suggests that subduction-related processes had already thermally weakened the continental lithosphere prior to the 27-25 Ma onset of volcanic activity.

  9. Effect of horseshoe crab spawning density on nest disturbance and exhumation of eggs: A simulation study (United States)

    Smith, D.R.


    Because the Delaware Bay horseshoe crab (Limulus polyphemus) population is managed to provide for dependent species, such as migratory shorebirds, there is a need to understand the process of egg exhumation and to predict eggs available to foraging shorebirds. A simple spatial model was used to simulate horseshoe crab spawning that would occur on a typical Delaware Bay beach during spring tide cycles to quantify density-dependent nest disturbance. At least 20% of nests and eggs were disturbed for levels of spawning greater than one third of the average density in Delaware Bay during 2004. Nest disturbance increased approximately linearly as spawning density increased from one half to twice the 2004 level. As spawning density increased further, the percentage of eggs that were disturbed reached an asymptote of 70% for densities up to 10 times the density in 2004. Nest disturbance was heaviest in the mid beach zone. Nest disturbance precedes entrainment and begins the process of exhumation of eggs to surface sediments. Model predictions were combined with observations from egg surveys to estimate a snap-shot exhumation rate of 5-9% of disturbed eggs. Because an unknown quantity of eggs were exhumed and removed from the beach prior to the survey, cumulative exhumation rate was likely to have been higher than the snap-shot estimate. Because egg exhumation is density-dependent, in addition to managing for a high population size, identification and conservation of beaches where spawning horseshoe crabs concentrate in high densities (i.e., hot spots) are important steps toward providing a reliable food supply for migratory shorebirds. ?? 2007 Estuarine Research Federation.

  10. Potential links between porphyry copper deposits and exhumed metamorphic basement complexes in northern Chile (United States)

    Cooper, Frances; Docherty, Alistair; Perkins, Rebecca


    Porphyry copper deposits (PCDs) are typically associated with magmatic arcs in compressional subduction zone settings where thickened crust and fractionated calc-alkaline magmas produce favourable conditions for copper mineralisation. A classic example is the Eocene-Oligocene PCD belt of Chile, the world's leading copper producing country. In other parts of the world, older late Cretaceous to early Tertiary PCDs are found in regions of former subduction-related magmatism that have undergone subsequent post-orogenic crustal extension, such as the Basin and Range province of western North America, and the Eurasian Balkan-Carpathian-Dinaride belt. In the Basin and Range there is a striking correlation between the location of many PCDs and exhumed metamorphic core complexes (isolated remnants of the middle to lower crust exhumed during extensional normal faulting). This close spatial relationship raises questions about the links between the two. For example, are their exhumation histories related? Could the presence of impermeable metamorphic rocks at depth affect and localise mineralising fluids? In Chile there appears to be a similar spatial relationship between PCDs and isolated outcrops of exhumed metamorphic basement. In northern Chile, isolated exposures of high-grade metamorphic gneisses and amphibolites are thought to be exhumed remnants of the pre-subduction Proterozoic-Paleozoic continental margin of Gondwana [2], although little is known about when they were exhumed and by what mechanism. For example, the Limón Verde metamorphic complex, exhumed from a depth of ca. 50 km, is situated adjacent to Chuquicamata, the largest open pit copper mine in the world. In northernmost Chile, another metamorphic exposure, the Belén complex, sits close to the Dos Hermanos PCD, a small deposit that is not actively mined. Comprising garnet-bearing gneisses and amphibolites, the Belén is thought to have been exhumed from a depth of ca. 25 km, but when and how is unclear [3

  11. [Approaches to setting up the Center for identification of exhumed bodies in Chechen Republic]. (United States)

    Klevno, V A; Ivanov, P L


    The authors participated in the activity of a group of European experts who visited Moscow, Rostov-on-Don and Grozny in September 2005 to clarify situation with identification of exhumed unknown dead bodies of the civil population. The European experts recommend to set up Center for Identification in Chechen Republic (in Grozny). The authors propose to make DNA identification tests in the Russian Federation Center for Forensic Medical Evaluation in Moscow which has much experience and staff skilled in identification of unknown exhumed bodies and can solve the problem of genetic identification of unidentified bodies of people missed in the Chechen Republic more effectively.

  12. Resolving spatial heterogeneities in exhumation and surface uplift in Timor-Leste : Constraints on deformation processes in young orogens

    NARCIS (Netherlands)

    Tate, Garrett W.; McQuarrie, Nadine; van Hinsbergen, D.J.J.; Bakker, Richard R.; Harris, Ron; Willett, Sean; Reiners, Peter W.; Fellin, Maria Giuditta; Ganerød, Morgan; Zachariasse, Willem Jan


    Although exhumation and surface uplift are important parameters in understanding orogenesis, the opportunity to measure both in close proximity is rare. In Timor-Leste (East Timor), deeply exhumed metamorphic rocks and piggyback deepwater synorogenic basins are only tens of kilometers apart, permitt

  13. Exhumation of high-pressure rocks in a Variscan migmatite dome (Montagne Noire, France) (United States)

    Whitney, Donna; Roger, Francoise; Rey, Patrice; Teyssier, Christian


    of garnet rims presents a challenge for ascribing the zircon rim age to hydrothermal alteration. Of the 5 reported eclogite localities in the MN, 4 are located near a high-strain zone along the long axis of the dome and one is located in a shear zone at the SSW margin of the gneissic core. 2D and 3D numerical models show that migmatite domes may form in response to extension of the upper crust, as the partially molten deep crust ascends along a steep, axial high strain zone and then flows into subdomes flanking this zone, forming a double dome such as the MN. This mode of dome formation is an efficient mechanism for rapid exhumation of deep crust. Migmatite dome rocks equilibrate at LP/HT, but eclogite inclusion in migmatite preserve their deep origin, track exhumation, and inform the internal dynamics of domes. Domes like the MN demonstrate that the opportunistic low-viscosity deep crust flows readily to fill gaps created by extensional/ transtensional domains in the collapsing late-Variscan orogen.

  14. Tectonics, exhumation, and drainage evolution of the eastern Himalaya since 13 Ma from detrital geochemistry and thermochronology, Kameng River Section, Arunachal Pradesh

    NARCIS (Netherlands)

    Chirouze, F.; Huyghe, P.; van der Beek, P.; Chauvel, C.; Chakraborty, T.; Dupont-Nivet, G.; Bernet, M.


    The exhumation history of the central Himalaya is well documented, but lateral variations in exhumation remain poorly constrained. In this study, we identify sediment source areas and examine the late Neogene exhumation history of the eastern Himalaya from the synorogenic sedimentary record of its f

  15. Mechanisms of continental subduction and exhumation of HP and UHP rocks

    NARCIS (Netherlands)

    Burov, Evgene; Francois, Thomas; Yamato, Philippe; Wolf, Sylvie


    We discuss possible scenarios of continental collision, and their relation to mechanisms of exhumation of HP and UHP rocks, inferred from thermo-mechanical numerical models accounting for thermo-rheological complexity of the continental lithosphere. Due to this complexity, mechanisms of continental

  16. Kinematics of post-orogenic extension and exhumation of the Taku Schist, NE Peninsular Malaysia

    NARCIS (Netherlands)

    Md Ali, M.A.; Willingshofer, E.|info:eu-repo/dai/nl/197475167; Matenco, L.|info:eu-repo/dai/nl/163604592; Francois, T.; Daanen, T.P.; Ng, T.F.; Taib, N.I.; Shuib, M.K.


    Abstract Recent studies imply that the formation and evolution of many SE Asian basins was driven by extensional detachments or systems of low-angle normal faults that created significant crustal exhumation in their footwalls. In this context, the architecture of the Triassic Indosinian orogen prese

  17. Long-term subsidence, cooling, and exhumation history along the South Atlantic passive continental margin in NW-Namibia (United States)

    Menges, Daniel; Glasmacher, Ulrich Anton; Salomon, Eric; Hackspacher, Peter Christian; Schneider, Gabi


    In northwest Namibia the Kaoko Belt is one of the most important Precambrian crustal segments that have stored the subsidence, cooling, and exhumation history of Namibia since the Neoproterozoic. ZFT-ages are processed to give new insights on this early evolution. Paleozoic to Mesozoic sedimentary rocks of the Karoo Supergroup and the Lower Cretaceous volcanic rocks of the Etendeka sequence overlay the Proterozoic metamorphic and intrusive rocks (1). New apatite fission-track (AFT) ages range from 390.9 (17.9) Ma to 80.8 (6.0) Ma. Along the coast apatites of Proterozoic rock samples reveal the youngest ages. Further inland the ages increase significantly. In addition, rapid change of AFT-ages occurs on both sides of major thrust and shear zones. Using the oldest thermochronological data the revealed t-T paths indicate a long era of exhumation, starting at the end of the Pan-African Orogeny in the Neoproterozoic and continuing into the Permo-Carboniferous. The subsequent sedimentation of the Karoo Supergroup initiates a new era of subsidence until the end of Triassic (2). The subsequent period of denudation ends abruptly with the rapid deposition of the Etendeka basalts in the Early Cretaceous (3). The maximum thickness of the Etendeka volcanic suite has been estimated, using the apatite fission-track data, to about 3.2 (1.2) km. With the ongoing opening of the South Atlantic and the formation of the continental margin the Kaoko Belt went through a rapid cooling event starting ~ 130 Ma and ending ~ 80 Ma, at a mean rate of 0.034 km/Ma for the western, and 0.018 km/Ma for the northern and eastern Kaoko Belt. This cooling event was accompanied by a reactivation of major fault zones, like the Purros Mylonite Zone (4). Thereafter, stable conditions were established, with denudation rates generally lower than 0.010 km/Ma, until the Neogene, where a second cooling event led to increased exhumation rates around 0.042 km/Ma. The total amount of denudation in the last 130 Ma

  18. Multidisciplinary design approach and safety analysis of ADSR cooled by buoyancy driven flows

    NARCIS (Netherlands)

    Ceballos Castillo, C.A.


    Transmutation is useful to reduce the storing time and the amount of nuclear waste to be stored in the geological repository. Transmutation can be achieved in all types of reactors: thermal systems, fast systems, critical and subcritical systems. Fast spectrum systems have significant advantages bec

  19. Particle fluid interactivity deteriorates buoyancy driven thermal transport in nanosuspensions : A multi component lattice Boltzmann approach

    CERN Document Server

    S, Savithiri; Pattamatta, Arvind; Das, Sarit K


    Severe contradictions exist between experimental observations and computational predictions regarding natural convective thermal transport in nanosuspensions. The approach treating nanosuspensions as homogeneous fluids in computations has been pin pointed as the major contributor to such contradictions. To fill the void, inter particle and particle fluid interactivities (slip mechanisms), in addition to effective thermophysical properties, have been incorporated within the present formulation. Through thorough scaling analysis, the dominant slip mechanisms have been identified. A Multi Component Lattice Boltzmann Model (MCLBM) approach has been proposed, wherein the suspension has been treated as a non homogeneous twin component mixture with the governing slip mechanisms incorporated. The computations based on the mathematical model can accurately predict and quantify natural convection thermal transport in nanosuspensions. The role of slip mechanisms such as Brownian diffusion, thermophoresis, drag, Saffman ...

  20. Numerical analysis of two and three dimensional buoyancy driven water-exit of a circular cylinder

    Directory of Open Access Journals (Sweden)

    Moshari Shahab


    Full Text Available With the development of the technology of underwater moving bodies, the need for developing the knowledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free surface deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an external force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simulation errors of present work (using VOF method for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.

  1. Developing Buoyancy Driven Flow of a Nanofluid in a Vertical Channel Subject to Heat Flux

    Directory of Open Access Journals (Sweden)

    Nirmal C. Sacheti


    Full Text Available The developing natural convective flow of a nanofluid in an infinite vertical channel with impermeable bounding walls has been investigated. It is assumed that the nanofluid is dominated by two specific slip mechanisms and that the channel walls are subject to constant heat flux and isothermal temperature, respectively. The governing nonlinear partial differential equations coupling different transport processes have been solved numerically. The variations of velocity, temperature, and nanoparticles concentration have been discussed in relation to a number of physical parameters. It is seen that the approach to the steady-state profiles of velocity and temperature in the present work is different from the ones reported in a previous study corresponding to isothermal wall conditions.

  2. Buoyancy-driven leakage of oil from a ruptured submarine pipeline

    NARCIS (Netherlands)

    Kranenburg, C.


    The rupture of a submarine oil pipeline starts various mechanisms leading to an oil spill. Among these mechanisms the leakage of oil driven by the difference in specific gravities of oil and sea-water is difficult to estimate. A simple mathematical model has been developed and laboratory experiments

  3. Critical conditions for the buoyancy-driven detachment of a wall-bound pendant drop (United States)

    Lamorgese, A.; Mauri, R.


    We investigate numerically the critical conditions for detachment of an isolated, wall-bound emulsion droplet acted upon by surface tension and wall-normal buoyancy forces alone. To that end, we present a simple extension of a diffuse-interface model for partially miscible binary mixtures that was previously employed for simulating several two-phase flow phenomena far and near the critical point [A. G. Lamorgese et al. "Phase-field approach to multiphase flow modeling," Milan J. Math. 79(2), 597-642 (2011)] to allow for static contact angles other than 90°. We use the same formulation of the Cahn boundary condition as first proposed by Jacqmin ["Contact-line dynamics of a diffuse fluid interface," J. Fluid Mech. 402, 57-88 (2000)], which accommodates a cubic (Hermite) interpolation of surface tensions between the wall and each phase at equilibrium. We show that this model can be successfully employed for simulating three-phase contact line problems in stable emulsions with nearly immiscible components. We also show a numerical determination of critical Bond numbers as a function of static contact angle by phase-field simulation.

  4. Experimental Study of Wind-Opposed Buoyancy-Driven Natural Ventilation

    DEFF Research Database (Denmark)

    Andersen, A.; Bjerre, M.; Chen, Z. D.;

    Natural ventilation driven by natural forces, i.e. wind and thermal buoyancy, is an environmentally friendly system for buildings and has been increasingly used around the world in recent years to mitigate the impact on the global environment due to the significant energy consumption by heating......, ventilation and air-conditioning (HV AC). There is a need for the understanding and development of theories and tools related to the design, operation and control of natural ventilation systems....

  5. Influence of rheology on buoyancy driven instabilities of miscible displacements in 2D micromodels (United States)

    D'Angelo, M. V.; Auradou, H.; Rosen, M.; Hulin, J. P.


    The stability of miscible displacements of Newtonian and shear-thinning fluids of slightly different densities (Δρ/ρ approx 3× 10-4) with a mean flow velocity U is investigated in a 2D transparent network of channels (average width = 0.33 mm). Concentration maps providing information at both the global and local scale are obtained through optical absorption measurements and compared in gravitationally stable and unstable vertical flow configurations; the influence of buoyant flows of typical velocity Ug is characterized by the gravity number Ng = Ug/|U|. For Ng glycerol solution, ld is only the same in the stable and unstable configurations for |Ng| 0.2, front spreading is not diffusive any more. In the stable configuration, in contrast, the front is flattened by buoyancy for Ng solution, both the concentration maps and the value of ld are the same in the stable and unstable configurations over the full range of U values investigated: this stabilization is explained by their high effective viscosity at low shear rates keeping Ng below the instability threshold even at the lowest velocities.

  6. Analytical and experimental study of instabilities in buoyancy-driven convection in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Georgiadis, J.G.; Behringer, R.; Johnson, G.A.


    During the second year of support under the DOE grant, significant progress was made in two directions: (1) Visualization of structure and tow field in randomly packed beds via Magnetic Resonance Imaging, and (2) Shadowgraphic visualization of natural convection in porous systems. This report describes the activities in detail, cite publications which resulted from this project, and conclude with plans for the last phase of the experimental investigation.

  7. Particle fluid interactivity deteriorates buoyancy driven thermal transport in nanosuspensions : A multi component lattice Boltzmann approach


    S, Savithiri; Dhar,Purbarun; Pattamatta, Arvind; Das, Sarit K


    Severe contradictions exist between experimental observations and computational predictions regarding natural convective thermal transport in nanosuspensions. The approach treating nanosuspensions as homogeneous fluids in computations has been pin pointed as the major contributor to such contradictions. To fill the void, inter particle and particle fluid interactivities (slip mechanisms), in addition to effective thermophysical properties, have been incorporated within the present formulation...

  8. Modeling the buoyancy-driven Black Sea Water outflow into the North Aegean Sea

    Directory of Open Access Journals (Sweden)

    Nikolaos Kokkos


    Full Text Available A three-dimensional numerical model was applied to simulate the Black Sea Water (BSW outflux and spreading over the North Aegean Sea, and its impact on circulation and stratification–mixing dynamics. Model results were validated against satellite-derived sea surface temperature and in-situ temperature and salinity profiles. Further, the model results were post-processed in terms of the potential energy anomaly, ϕ, analyzing the factors contributing to its change. It occurs that BSW contributes significantly on the Thracian Sea water column stratification, but its signal reduces in the rest of the North Aegean Sea. The BSW buoyancy flux contributed to the change of ϕ in the Thracian Sea by 1.23 × 10−3 W m−3 in the winter and 7.9 × 10−4 W m−3 in the summer, significantly higher than the corresponding solar heat flux contribution (1.41 × 10−5 W m−3 and 7.4 × 10−5 W m−3, respectively. Quantification of the ϕ-advective term crossing the north-western BSW branch (to the north of Lemnos Island, depicted a strong non-linear relation to the relative vorticity of Samothraki Anticyclone. Similar analysis for the south-western branch illustrated a relationship between the ϕ-advective term sign and the relative vorticity in the Sporades system. The ϕ-mixing term increases its significance under strong winds (>15 m s−1, tending to destroy surface meso-scale eddies.

  9. Microliter-bioreactor array with buoyancy-driven stirring for human hematopoietic stem cell culture


    Luni, Camilla; Feldman, Hope C.; Pozzobon, Michela; De Coppi, Paolo; Meinhart, Carl D.; Elvassore, Nicola


    This work presents the development of an array of bioreactors where finely controlled stirring is provided at the microliter scale (100–300 μl). The microliter-bioreactor array is useful for performing protocol optimization in up to 96 parallel experiments of hematopoietic stem cell (HSC) cultures. Exploring a wide range of experimental conditions at the microliter scale minimizes cost and labor. Once the cell culture protocol is optimized, it can be applied to large-scale bioreactors for ste...

  10. Buoyancy-driven flow in a peat moss layer as a mechanism for solute transport

    NARCIS (Netherlands)

    Rappoldt, C.; Pieters, G.J.J.M.; Adema, E.B.; Baaijens, G.J.; Grootjans, A.P.; Duijn, van C.J.


    Transport of nutrients, CO2, methane, and oxygen plays an important ecological role at the surface of wetland ecosystems. A possibly important transport mechanism in a water-saturated peat moss layer (usually Sphagnum cuspidatum) is nocturnal buoyancy flow, the downward flow of relatively cold surfa

  11. Multi-method geo- and thermochronology of glacially transported cobbles reveals the tectonic and exhumation history of the St. Elias Mountains (Alaska/Yukon) (United States)

    Falkowski, Sarah; Enkelmann, Eva; Drost, Kerstin; Pfänder, Jörg; Stübner, Konstanze; Ehlers, Todd


    -ridge subduction and associated formation and cooling of the Chugach Metamorphic Complex, the beginning of flat-slab subduction of the Yakutat microplate in the late Eocene-early Oligocene, the ongoing Yakutat-North American plate collision, and rapid exhumation of the St. Elias syntaxis. For a statistical analysis of erosion and sediment source, however, a higher number of cobbles would be necessary, which is not feasible due to the costly and time-consuming approach. Therefore, the combination of cobble- and sand-sized detritus analysis is recommended.

  12. Cenozoic Exhumation and Thrusting in the Northern Qilian Shan,Northeastern Margin of the Tibetan Plateau:Constraints from Sedimentological and Apatite Fission-Track Data

    Institute of Scientific and Technical Information of China (English)

    GUO Zhaojie; LU Jiemin; ZHANG Zhicheng


    The Qilian Shan lies along the northeastern edge of the Tibetan Plateau.To constrain its deformation history,we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediately north of the mountain range.Paleocurrent measurements,sandstone compositional data,and facies analysis of Cenozoic stratigraphic sections suggest that the Jiuxi Basin received sediments from the Altyn Tagh Range in the northwest,initially in the Oligocene(~33 Ma),depositing the Huoshaogou Formation in the northern part of the basin.Later,the source area of the Jiuxi Basin changed to the Qilian Shan in the south during Late Oligocene(~27 Ma),which led to the deposition of the Baiyanghe Formation.We suggest that uplift of the northern Qilian Shan induced by thrusting began no later than the Late Oligocene.Fission-track analysis of apatite from the Qilian Shan yields further jnformation about the deformation history of the northern Qilain Shan and the Jiuxi Basin.It shows that a period of rapid cooling,interpreted as exhumation,initiated in the Oligocene.We suggest that this exhumation marked the initial uplift of the Qilian Shan resulting from the India-Asia collision.

  13. Volcanosedimentary Basins in the Arabian-Nubian Shield: Markers of Repeated Exhumation and Denudation in a Neoproterozoic Accretionary Orogen

    Directory of Open Access Journals (Sweden)

    Victoria Pease


    Full Text Available The Arabian-Nubian Shield (ANS includes Middle Cryogenian-Ediacaran (790–560 Ma sedimentary and volcanic terrestrial and shallow-marine successions unconformable on juvenile Cryogenian crust. The oldest were deposited after 780–760 Ma shearing and suturing in the central ANS. Middle Cryogenian basins are associated with ~700 Ma suturing in the northern ANS. Late Cryogenian basins overlapped with and followed 680–640 Ma Nabitah orogenesis in the eastern ANS. Ediacaran successions are found in pull-apart and other types of basins formed in a transpressive setting associated with E-W shortening, NW-trending shearing, and northerly extension during final amalgamation of the ANS. Erosion surfaces truncating metamorphosed arc rocks at the base of these successions are evidence of periodic exhumation and erosion of the evolving ANS crust. The basins are evidence of subsequent subsidence to the base level of alluvial systems or below sea level. Mountains were dissected by valley systems, yet relief was locally low enough to allow for seaways connected to the surrounding Mozambique Ocean. The volcanosedimentary basins of the ANS are excellently exposed and preserved, and form a world-class natural laboratory for testing concepts about crustal growth during the Neoproterozoic and for the acquisition of data to calibrate chemical and isotopic changes, at a time in geologic history that included some of the most important, rapid, and enigmatic changes to Earth’s environment and biota.

  14. Cooling and exhumation of continents at billion-year time scales (United States)

    Blackburn, T.; Bowring, S. A.; Perron, T.; Mahan, K. H.; Dudas, F. O.


    The oldest rocks on Earth are preserved within the continental lithosphere, where assembled fragments of ancient orogenic belts have survived erosion and destruction by plate tectonic and surface processes for billions of years. Though the rate of orogenic exhumation and erosion has been measured for segments of an orogenic history, it remains unclear how these exhumation rates have changed over the lifetime of any terrane. Because the exhumation of the lithospheric surface has a direct effect on the rate of heat loss within the lithosphere, a continuous record of lithosphere exhumation can be reconstructed through the use of thermochronology. Thermochronologic studies have typically employed systems sensitive to cooling at temperatures <300 °C, such as the (U-Th)/He and 40Ar/39Ar systems. This largely restricts their application to measuring cooling in rocks from the outer 10 km of the Earth's crust, resulting in a thermal history that is controlled by either upper crustal flexure and faulting and/or isotherm inflections related to surface topography. Combining these biases with the uplift, erosion and recycling of these shallow rocks results in a poor preservation potential of any long-term record. Here, an ancient and long-term record of lithosphere exhumation is constructed using U-Pb thermochronology, a geochronologic system sensitive to cooling at temperatures found at 20-50 km depth (400-650 °C). Lower crustal xenoliths provide material that resided at these depths for billions of years or more, recording a thermal history that is buried deep enough to remain insensitive to upper crustal deformation and instead is dominated by the vertical motions of the continents. We show how this temperature-sensitive system can produce a long-term integrated measure of continental exhumation and erosion. Preserved beneath Phanerozoic sedimentary rocks within Montana, USA, the Great Falls Tectonic Zone formed when two Archean cratons, the Wyoming Province and Medicine

  15. Fission track ages and Exhumation mechanisms of the Tauern Window, Eastern Alps (United States)

    Bertrand, Audrey; Rosenberg, Claudio; Garcia, Sebastian


    The Tauern Window (TW) is a thermal and structural dome which exposes Penninic basement, its cover units as well as parts of the overlying Austroalpine basement in the central part of the Eastern Alps. The peak of metamorphism was attained approximately at 30Ma (Selverstone et .al, 1992), followed by cooling and exhumation throughout Miocene time. Most of the tertiary exhumation of the Eastern Alps was localized in the TW, from Early Oligocene to late Miocene time. A current debate centers on the exhumation mechanisms of Penninic rocks in the core of the TW, namely to assess whether orogen-parallel extension (e.g., Selverstone, 1988) or a combination of folding and erosion (eg., Rosenberg et al., 2004) with subordinate extension were the controlling processes. E-W extension is well documented at the western (Brenner Fault) and eastern (Katschberg Fault) margins of the window (e.g., Behrmann, 1988; Selverstone, 1988; Genser and Neubauer, 1989). In contrast, upright folding dominates the internal structure of the dome, and in particular along its western part, where fold amplitudes, mostly eroded during folding, attained up to 10 km. This study attempts to assess the relative importance of folding and erosion and of orogen-parallel extension during exhumation by analyzing the spatial and temporal cooling patterns of apatite and zircon fission track ages. The compilation of published apatite and zircon fission track ages indicates a concentric younging of both the apatite and zircon ages toward the core of the TW. The concentric isochrones follow the map trace of the axial planes of the upright folds of the western and eastern TW. This cooling pattern is in contrast to the one expected by a process of extensional unroofing, which in map view would results in isochrons parallel to the extensional faults and progressively younging towards them (e.g., Foster et al., 2001). We therefore propose that folding and erosion were primarily responsible for exhuming the Penninic

  16. Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages (United States)

    Schlup, M.; Steck, A.; Carter, A.; Cosca, M.; Epard, J.-L.; Hunziker, J.


    New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) - Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper Indian crust by 55. Ma and metamorphosed by ca. 48-40. Ma. The nappe stack was subsequently exhumed to shallow upper crustal depths (Elsevier Ltd.

  17. Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica) (United States)

    Malusà, Marco G.; Faccenna, Claudio; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Rossetti, Federico; Balestrieri, Maria Laura; Danišík, Martin; Ellero, Alessandro; Ottria, Giuseppe; Piromallo, Claudia


    Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary.

  18. Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages (United States)

    Schlup, Micha; Steck, Albrecht; Carter, Andrew; Cosca, Michael; Epard, Jean-Luc; Hunziker, Johannes


    New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) — Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper Indian crust by 55 Ma and metamorphosed by ca. 48–40 Ma. The nappe stack was subsequently exhumed to shallow upper crustal depths (

  19. Changing exhumation patterns during Cenozoic growth and glaciation of the Alaska Range: Insights from detrital thermochronology and geochronology (United States)

    Lease, Richard O.; Haeussler, Peter J.; O'Sullivan, Paul


    Cenozoic growth of the Alaska Range created the highest topography in North America, but the space-time pattern and drivers of exhumation are poorly constrained. We analyzed U/Pb and fission-track double dates of detrital zircon and apatite grains from 12 catchments that span a 450 km length of the Alaska Range to illuminate the timing and extent of exhumation during different periods. U/Pb ages indicate a dominant Late Cretaceous to Oligocene plutonic provenance for the detrital grains, with only a small percentage of grains recycled from the Mesozoic and Paleozoic sedimentary cover. Fission-track ages record exhumation during Alaska Range growth and incision and reveal three distinctive patterns. First, initial Oligocene exhumation was focused in the central Alaska Range at ~30 Ma and expanded outward along the entire length of the range until 18 Ma. Oligocene exhumation, coeval with initial Yakutat microplate collision >600 km to the southeast, suggests a far-field response to collision that was localized by the Denali Fault within a weak Mesozoic suture zone. Second, the variable timing of middle to late Miocene exhumation suggests independently evolving histories influenced by local structures. Time-transgressive cooling ages suggest successive rock uplift and erosion of Mounts Foraker (12 Ma) through Denali (6 Ma) as crust was advected through a restraining bend in the Denali Fault and indicate a long-term slip rate ~4 mm/yr. Third, Pliocene exhumation is synchronous (3.7-2.7 Ma) along the length of the Alaska Range but only occurs in high-relief, glacier-covered catchments. Pliocene exhumation may record an acceleration in glacial incision that was coincident with the onset of Northern Hemisphere glaciation.

  20. Exhumation of the North Alpine Foreland Basin- Quantitative insights from structural analysis, thermochronology and a new thermal history model (United States)

    Luijendijk, Elco; von Hagke, Christoph; Hindle, David


    Due to a wealth of geological and thermochronology data the northern foreland basin of the European Alps is an ideal natural laboratory for understanding the dynamics of foreland basins and their interaction with surface and geodynamic processes. We present an unprecedented compilation of thermochronological data from the basin and quantify cooling and exhumation rates in the basin by combining published and new vitrinite reflectance, apatite fission track and U-Th/He data with a new inverse burial and thermal history model. No correlation is obvious between inferred cooling and exhumation rates and elevation, relief or tectonics. We compare derived temperature histories to exhumation estimates based on the retro-deformation of Molasse basin and the Jura mountains, and to exhumation caused by drainage reorganization and incision. Drainage reorganization can explain at most 25% of the observed cooling rates in the basin. Tectonic transport of the basin's sediments over the inclined basement of the alpine foreland as the Jura mountains shortened can explain part of the cooling signal in the western part of the basin. However, overall a substantial amount of cooling and exhumation remains unexplained by known tectonic and surface processes. Our results document basin wide exhumation that may be related to slab roll-back or other lithospheric processes. Uncertainty analysis shows that thermochronometers can be explained by cooling and exhumation starting as early as the Miocene or as late as the Pleistocene. New (U-Th)/He data from key areas close to the Alpine front may provide better constraints on the timing of exhumation.

  1. Numerical modeling of mantle wedge processes and exhumation of UHP mantle in subduction zones (United States)

    Gorczyk, W.; Gerya, T. V.; Guillot, S.; Connolly, J. A.; Yuen, D.


    The upwelling of subduction generated partially molten rocks is potentially a mechanism for the exhumation of UHP rocks through the mantle wedge. We investigated this processes using a 2-D coupled petrological- thermomechanical model that incorporates slab dehydration and water transport as well as partial melting of mantle and crustal rocks. This approach allows us to study the dynamics of mantle wedge processes including evolution of partially molten plumes and their interaction with surrounding dry mantle. To study the internal structure of the plumes we used ultra-high resolution numerical simulations with 10 billion active markers to detail the internal structure of natural plumes originating from the slab. The plumes consist of partially molten hydrated peridotite, dry solid mantle and subducted oceanic crust, which may comprise up to 12 volume % of the plume. As the plumes grow and mature these materials mix chaotically resulting in attenuation and duplication of the original layering on scales of 1-1000 m. Comparison of numerical results with geological observations from the Horoman ultramafic complex in Japan suggests that mixing and differentiation processes related to development of partially molten plumes above slabs may be responsible for strongly layered lithologically mixed (marble cake) structure of asthenospheric mantle wedges. The recent discovery of garnet bearing peridotites in the subduction zone of the Great Antilles in Hispaniola has raised questions about the process that leads to their exhumation. To evaluate whether upwelling plumes are a plausible exhumation mechanism we investigated the dynamics of subduction of slow spreading ridges. The results show that subduction of strongly serpentinized oceanic plate causes strong dehydration of the slab and leads to a rheological weakening of the interface between subducting and overriding plate. This weakening triggers trench retreat and massive asthenospheric upwelling into the gap between the

  2. Differential exhumation rates across the Longriba fault system : insights from low temperature thermochronology (United States)

    Ansberque, Claire; Godard, Vincent; Bellier, Olivier; De Sigoyer, Julia; Bernet, Matthias; Ehlers, Todd; Stuebner, Konstanze; Wang, Mingming; Tan, Xibin; Xu, Xiwei


    The eastern Tibetan margin forms one of the steepest topographic escarpment in the world. Most of the current deformation of this area appears to be accommodated in the Longmen Shan thrust system whose major seismogenic potential is attested by the 2008 Wenchuan earthquake. Yet, the velocity gradient across the margin revealed by GPS measurements decreases significantly 200 km north the Longmen Shan. These observations suggest that other tectonic structures might contribute to the global deformation in eastern Tibet, in particular the Longriba fault system (LFS). For over fifteen years, the Longmen Shan have been the focus of many thermochronological investigations, which have gradually contributed to produce a large database and allowed to better constrain the history and patterns of exhumation of the eastern Tibetan margin. Comparatively, there is significantly fewer thermochronology data near the LFS. This structure has been recognized as a main structure of the margin accommodating much of the Aba block motion (with respect to the Longmen Shan). But, although its Holocene tectonic activity has been investigated, its long-term behavior remains unclear, and its present-day geodynamical role over Late Cenozoic timescales is still uncertain. To better constrain this issue, we used fission tracks and (U-Th)/He on apatites and zircons, on samples located across the two main faults of the LFS and more particularly on both sides of the Maoergai fault. The results show two very contrasted Late Cenozoic exhumation patterns: at the Oligocene, samples north but very close to the fault display an exhumation rate of 40 m/Ma, while at the Miocene, samples south the fault show an exhumation rate of 170 m/Ma. Such discrepancy could reflect two distinct incision periods of the margin and could also highlight the role of the Maoergai fault in the control of this incision pattern.

  3. Uplift, exhumation and erosion along the Angolan continental margin: an integrated approach (United States)

    Gröger, Heike R.; Machado, Vladimir; Di Pinto, Giuseppe


    The topographical development along the SW African margin is not exclusively rift-related. In addition to the onset of rifting in the Early Cretaceous, additional Late Cretaceous and Cenozoic events of uplift, exhumation and erosion are discussed. Thermochronology has proven to be a valuable tool to constrain phases of exhumation in passive continental margins. For South Africa and Namibia a large number of thermochronological data are available. Angola on the other hand is still scarcely investigated. This study is based on thermochronological data from onshore Angola, integrated with quantitative morphotectonic analysis and the on- and offshore stratigraphic record. In South Africa and Namibia published thermochronological data document pronounced Early and Late Cretaceous cooling events, which can be related to 2.5-3.5 km of removed section during the Cretaceous. An additional 1-2 km of removed section are estimated during the Cenozoic. In Angola predominantly Permo-Triassic apatite fission track ages indicate significantly less Cretaceous to Cenozoic erosion (appear directly linked. Cenozoic erosion onshore is mirrored by enhanced Oligocene to Miocene sedimentation offshore. The geomorphological information as well as the stratigraphic record are compatible with the Cenozoic cooling and exhumation as suggested by thermal modelling of apatite fission track data. Although direct indicators for Cretaceous cooling and erosion are missing in Angola, minor amounts of Cretaceous erosion may be disguised by the Miocene final event.

  4. Fluid inclusions evidence for differential exhumation of ultrahigh pressure metamorphic rocks in the Sulu terrane

    Institute of Scientific and Technical Information of China (English)

    FAN Hongrui; GUO Jinghui; HU Fangfang; CHU Xuelei; CHEN Fukun; JIN Chengwei


    Differential exhumation was petrologically recognized in ultrahigh pressure metamorphic rocks from the southern and northern parts of the Sulu terrane. While a normal exhumation occurred for eclogites and gneisses in south Sulu, granulite-facies overprinting of ultrahigh pressure metamorphic rocks took place with high retrograde temperatures in north Sulu. A study of fluid inclusions reveals trapping of five type fluid inclusions in high and ultrahigh pressure eclogite minerals and vein quartz in the Sulu terrane. These are A-type N2±CO2 inclusion trapped at high and ultra-high pressure eclogite-facies metamorphic condition, B-type pure-CO2 liquid phase inclusion with higher density trapped during granulite-facies overprinting metamorphism of eclogites, C-type CO2-H2O inclusion and D-type hypersaline inclusion trapped in high pressure eclogite-facies re-crystallization stage, and E-type low salinity H2O inclusion trapped in the latest stage of ultrahigh pressure exhumation (amphibolite-facies retrogression). Identification of crowded-distributing pure-CO2 liquid inclusions with higher density trapped in garnet of eclogites provides an evidence for granulite-facies overprinting metamorphism in the north Sulu terrane.

  5. Trace-element record in zircons during exhumation from UHP conditions, North-East Greenland Caledonides (United States)

    McClelland, W.C.; Gilotti, J.A.; Mazdab, F.K.; Wooden, J.L.


    Coesite-bearing zircon formed at ultrahigh-pressure (UHP) conditions share general characteristics of eclogite-facies zircon with trace-element signatures characterized by depleted heavy rare earth elements (HREE), lack of an Eu anomaly, and low Th/ U ratios. Trace-element signatures of zircons from the Caledonian UHP terrane in North-East Greenland were used to examine the possible changes in signature with age during exhumation. Collection and interpretation of age and trace-element analyses of zircon from three samples of quartzofeldspathic gneiss and two leucocratic intrusions were guided by core vs. rim zoning patterns as imaged by cathodoluminesence. Change from igneous to eclogite-facies metamorphic trace-element signature in protolith zircon is characterized by gradual depletion of HREE, whereas newly formed metamorphic rims have flat HREE patterns and REE concentrations that are distinct from the recrystallized inherited cores. The signature associated with eclogite-facies metamorphic zircon is observed in coesite-bearing zircon formed at 358 ?? 4 Ma, metamorphic rims formed at 348 ?? 5 Ma during the initial stages of exhumation, and metamorphic rims formed at 337 ?? 5 Ma. Zircons from a garnet-bearing granite emplaced in the neck of an eclogite boudin and a leucocratic dike that cross-cuts amphibolite-facies structural fabrics have steeply sloping HREE patterns, variably developed negative Eu anomalies, and low Th/U ratios. The granite records initial decompression melting and exhumation at 347 ?? 2 Ma and later zircon rim growth at 329 ?? 5. The leucocratic dike was likely emplaced at amphibolite-facies conditions at 330 ?? 2 Ma, but records additional growth of compositionally similar zircon at 321 ??2 Ma. The difference between the trace-element signature of metamorphic zircon in the gneisses and in part coeval leucocratic intrusions indicates that the zircon signature varies as a function of lithology and context, thus enhancing its ability to aid in

  6. Rapid PCR thermocycling using microscale thermal convection. (United States)

    Muddu, Radha; Hassan, Yassin A; Ugaz, Victor M


    Many molecular biology assays depend in some way on the polymerase chain reaction (PCR) to amplify an initially dilute target DNA sample to a detectable concentration level. But the design of conventional PCR thermocycling hardware, predominantly based on massive metal heating blocks whose temperature is regulated by thermoelectric heaters, severely limits the achievable reaction speed(1). Considerable electrical power is also required to repeatedly heat and cool the reagent mixture, limiting the ability to deploy these instruments in a portable format. Thermal convection has emerged as a promising alternative thermocycling approach that has the potential to overcome these limitations(2-9). Convective flows are an everyday occurrence in a diverse array of settings ranging from the Earth's atmosphere, oceans, and interior, to decorative and colorful lava lamps. Fluid motion is initiated in the same way in each case: a buoyancy driven instability arises when a confined volume of fluid is subjected to a spatial temperature gradient. These same phenomena offer an attractive way to perform PCR thermocycling. By applying a static temperature gradient across an appropriately designed reactor geometry, a continuous circulatory flow can be established that will repeatedly transport PCR reagents through temperature zones associated with the denaturing, annealing, and extension stages of the reaction (Figure 1). Thermocycling can therefore be actuated in a pseudo-isothermal manner by simply holding two opposing surfaces at fixed temperatures, completely eliminating the need to repeatedly heat and cool the instrument. One of the main challenges facing design of convective thermocyclers is the need to precisely control the spatial velocity and temperature distributions within the reactor to ensure that the reagents sequentially occupy the correct temperature zones for a sufficient period of time(10,11). Here we describe results of our efforts to probe the full 3-D velocity and

  7. Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U-Pb and 40Ar-39Ar geochronology (United States)

    Pereira, M. Francisco; Chichorro, Martim; Silva, J. Brandão; Ordóñez-Casado, Berta; Lee, James K. W.; Williams, Ian S.


    New U-Pb and 40Ar-39Ar geochronology and structural data from high- to medium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U-Pb age of 465 ± 14 Ma (Middle Ordovician) measured on migmatite from the Coimbra-Cordoba shear zone is interpreted as the age of protolith crystallization. This age determination revises the information contained in the geological map of Portugal, in which these rocks were considered to be Proterozoic in age. This paper describes the evolution of Variscan wrench tectonics related to the development of shear zones, exhumation of deep crustal rocks and emplacement of magma in the Ossa-Morena Zone basement. In the Coimbra-Cordoba shear zone (transpressional), migmatites were rapidly exhumed from a depth of 42.5 km to 16.6 km over a period of ca. 10 Ma in the Viséan (ca. 340-330 Ma), indicating oblique slip exhumation rates of 8.5 to 10.6 mm/yr (Campo Maior migmatites) and 3.2 mm/yr (Ouguela gneisses) respectively. In the Évora Massif, the gneisses of the Boa Fé shear zone (transtensional) were exhumed from 18.5 to 7.4 km depth in the period ca. 344-334 Ma (Viséan), with exhumation oblique slip rates of 2.8 to 4.2 mm/yr. At the same time, the Early Carboniferous basins of SW Iberia were filled by turbidites and olistoliths, composed mostly of Devonian rocks. The presence of olistoliths indicates significant tectonic instability during sedimentation with large-scale mass movement, probably in the form of gravity slides. Deformation and metamorphism dated at 356 ± 12 Ma, 321 ± 13 Ma and 322 ± 29 Ma respectively suggests that Variscan wrench movements were active in SW Iberia during the Early Carboniferous for a period of at least 35 Ma.

  8. Styles of continental subduction and collision and their effect on formation and exhumation of UHP rocks (United States)

    Warren, C. J.; Beaumont, C.; Jamieson, R. A.


    Ultra-high pressure (UHP) metamorphic rocks are exposed in many Phanerozoic mountain belts. It is now widely accepted that they represent continental margin rocks that were subducted to ≥100km during the transition from oceanic subduction to continental collision. A range of subduction-collision mechanisms have been proposed to account for UHP formation and exhumation. A series of upper-mantle-scale geodynamic models is used to test the sensitivity of a subset of these mechanisms to variations in lithosphere density, radioactive heat production, and crustal strength. The subducting crust includes an oceanic domain, a continental margin domain with variable width, thickness, strength, and heat production, and a strong internal continental domain. The models involve dynamic subduction, constant convergence velocity, density changes that accompany the main phase changes during burial, and surface erosion in the collision zone. Results show that continental subduction without retro-continent deformation is favored by relatively dense mantle lithosphere. Subduction of the retro-continent (forearc subduction) is associated with shallow-dipping, low- density mantle lithosphere. Back-thrusting of retro-lithosphere is favored by relatively weak retro-continental crust. UHP material can be exhumed in all 3 model styles, depending on the evolving geometry of the subduction-accretion zone and the degree of decoupling between subducting upper and lower continental crust in this zone. Weaker and/or hotter margins decouple and accrete, and their subsequent exhumation is driven by bulk density contrast (buoyancy) and/or forced expulsion in response to advection of strong continental material into the subduction zone (plunger effect). Stronger and/or colder continental margin material is subducted without decoupling and is then transported laterally, underplating the retro-mantle lithosphere. Model results are compatible with observed geometries and PTt paths from some UHP

  9. Apatite fission-track thermochronological constraints on the pattern of late Mesozoic-Cenozoic uplift and exhumation of the Qinling Orogen, central China (United States)

    Chen, Hong; Hu, Jianmin; Wu, Guoli; Shi, Wei; Geng, Yingying; Qu, Hongjie


    The Qinling Orogen of central China was formed by intracontinental collision between the North and South China Blocks. The orogen comprises several micro-blocks bounded by sutures and faults, and has undergone long-term intracontinental deformation since the Late Triassic. The micro-blocks include the southern margin of the North China Block (S-NCB), the Northern Qinling Belt (NQB), the Southern Qinling Belt (SQB), and the northern margin of the South China Block (N-SCB). Under a uniform tectonic setting in late Mesozoic-Cenozoic, these micro-blocks have been subjected to a range of deformation styles, as demonstrated by their structural deformation, history of magmatism, and the development of sedimentary basins. To investigate the differences among the micro-blocks and to quantify their uplift and exhumation, we obtained 45 rock samples from eight Mesozoic granites in these micro-blocks, and conducted apatite fission-track (AFT) thermochronological modeling. The results reveal that the Qinling Orogen underwent four distinct stages of rapid cooling histories during the late Mesozoic-Cenozoic, and showed variation in uplift and exhumation whereby the intracontinental deformation started in the south (the N-SCB) and propagated to the north (S-NCB). In the first stage, during the Late Jurassic-Early Cretaceous (ca. 160-120 Ma), rock cooling occurred mainly in the N-SCB, attributed to the clockwise rotation and northward subduction of the South China Block beneath the Qinling Orogen. In the second stage, compression- and extension-related uplift was initiated during the late Early Cretaceous-early Late Cretaceous (ca. 120-90 Ma) in the SQB, consistent with the southward subduction of the North China Block and broadly extensional deformation in the eastern China continent. In the third stage, a gentle regional-scale cooling event that occurred during the latest Cretaceous-Paleocene (ca. 90-50 Ma) started in the NQB and became widespread in the Qinling Orogen. This

  10. Formation Mechanism and Exhumation Processes for HP-UHP Metamorphic Rocks in Dabie Mountains

    Institute of Scientific and Technical Information of China (English)

    Hou Mingjin; Tang Jiafu


    The high, ultrahigh pressure metamorphic rocks, widely distributed in Dabie Mountains, were described in terms of the geological setting, the marks of the petrology and the mineralogy of the ultrahigh pressure (UHP) metamorphic rocks. According to the estimated uplifting and denudation of the Dabie Mountains, and to the thermodynamics theory, were assessed the depth and pressure (high pressure autoclave) of the formation setting of the UHP metamorphic rocks. Based on all the information mentioned above, a new explanation is derived from the mechanism of formation and the processes of exhumation of the UHP metamorphic rocks.

  11. The Influence of Localized Glacial Erosion on Exhumation Paths in Accreting Coulomb Wedges: Insights from Particle Velocimetry Analysis of Sandbox Models (United States)

    Newman, P. J.; Davis, K.; Haq, S. S. B.; Ridgway, K.


    Glacial erosion can have an impact on the location and development of faults in mountain belts. The rapid removal and deposition of rock, in some cases, is thought to affect the initiation of slip on older fault structures, or cause the development of new structures within the older part of the wedge. We present cross-sectional data from both erosional and non-erosional sandbox models of Coulomb wedges in order to quantify the impact of localized erosion on the location of and slip on deformational structures, as well as the general path of material through a wedge. To do this, we employ Lagrangian particle tracking velocimetry (PTV) using the open-source Python PTV toolkit trackpy, among a suite of other data analysis tools. We are able to extract robust and reliable sets of particle trajectories from a series of images without the need for predefined markers or marker-beds, instead identifying and tracking natural variations in sand color as individual particles. By comparing the motion of particles in cross-section to the local surface topography over an entire experiment, we determine a high-resolution record of exhumation rates, in addition to simple uplift rates. These comparisons are further informed by the use of high-definition Eulerian particle image velocimetry (PIV), which provides quantitative data about the distribution of deformation and instantaneous material displacements throughout a cross-sectional view of a Coulomb wedge. This allows us to interpret these pathways in relation to the behavior of active structures and general wedge morphology. In our experiments, we observe that localized glacial erosion has an impact on material pathways, in the form of an increased rate of exhumation locally, more vertical trajectories towards surface below the zone of erosion, and reactivation of older structures to maintain force balance within the entire wedge.

  12. Role of Neogene Exhumation and Sedimentation on Critical-Wedge Kinematics in the Zagros Orogenic Belt, Northeastern Iraq, Kurdistan (United States)

    Koshnaw, R. I.; Horton, B. K.; Stockli, D. F.; Barber, D. E.; Tamar-Agha, M. Y.; Kendall, J. J.


    The Zagros orogenic belt and foreland basin formed during the Cenozoic Arabia-Eurasia collision, but the precise histories of shortening and sediment accumulation remain ambiguous, especially at the NW extent of the fold-thrust belt in Iraqi Kurdistan. This region is characterized by well-preserved successions of Cenozoic clastic foreland-basin fill and deformed Paleozoic-Mesozoic hinterland bedrock. The study area provides an excellent opportunity to investigate the linkage between orogenic wedge behavior and surface processes of erosion and deposition. The aim of this research is to test whether the Zagros orogenic wedge advanced steadily under critical to supercritical wedge conditions involving in-sequence thrusting with minimal erosion or propagated intermittently under subcritical condition involving out-of-sequence deformation with intense erosion. These endmember modes of mountain building can be assessed by integrating geo/thermochronologic and basin analyses techniques, including apatite (U-Th)/He thermochronology, detrital zircon U-Pb geochronology, stratigraphic synthesis, and seismic interpretations. Preliminary apatite (U-Th)/He data indicate activation of the Main Zagros Fault (MZF) at ~10 Ma with frontal thrusts initiating at ~8 Ma. However, thermochronometric results from the intervening Mountain Front Flexure (MFF), located between the MZF and the frontal thrusts, suggest rapid exhumation at ~6 Ma. These results suggest that the MFF, represented by the thrust-cored Qaradagh anticline, represents a major episode of out-of-sequence deformation. Detrital zircon U-Pb analyses from the Neogene foreland-basin deposits show continuous sediment derivation from sources to the NNE in Iraq and western Iran, suggesting that out-of-sequence thrusting did not significantly alter sedimentary provenance. Rather, intense hinterland erosion and recycling of older foreland-basin fill dominated sediment delivery to the basin. The irregular distribution of

  13. Contrasting exhumation P-T paths followed by high-P rocks in the northern Caribbean subduction-accretionary complex: Insights from the structural geology, microtextures and equilibrium assemblage diagrams (United States)

    Escuder-Viruete, Javier; Pérez-Estaún, Andrés


    The Río San Juan metamorphic complex exposes a segment of a high-pressure subduction-accretionary complex built during convergence between the Caribbean island arc and the North America continental margin. It is composed of accreted arc- and oceanic-derived metaigneous rocks, serpentinized peridotites and minor metasediments forming a structural pile. Combined structural geology, microtextural relations, multi-equilibrium calculations and thermodynamical modelling, together with published isotopic ages, allow reconstructing the metamorphic P-T-t paths of each nappe/unit and their links to the structural evolution. In all units of the complex, three major stages (M1 to M3) in the tectonothermal evolution have been distinguished. The M1 stage corresponds to the prograde evolution towards the pressure-peak of metamorphism under blueschist or eclogitic-facies conditions. The M2 stage is related to the main retrogressive event and is characterized by the S2-L2 fabric development in all lithologies and at all scales. The M3 stage represents continuous exhumation from ductile to ductile-brittle deformation regimes. However, the shape of the retrograde P-T path, the age of the exhumation-related D2 structures and the tectonic significance of D2 deformation are different in each structural unit. In the upper structural levels of the Jagua Clara serpentinitic-matrix mélange, the counter-clockwise P-T path of the eclogite blocks is typical of rocks exhumed in the early stages of intra-oceanic subduction zones. The clockwise P-T path obtained for the lower Cuaba unit is characterized by a strong isothermal decompression from the garnet-epidote amphibolite and eclogite-facies pressure-peak. This P-T evolution can be explained by rapid exhumation caused by extensional tectonics, in relation to a major modification of convergence conditions across the subduction zone. The P-T path also explains local syn-M2 partial melting processes, because it crosses the wet solidus for IAT

  14. Tales from the grave: Opposing autopsy reports from a body exhumed. (United States)

    Gunasekera, R S; Brown, A B; Costas, E H


    We report an autopsy case of a 42-year-old woman who, when discovered, had been dead in her apartment for approximately 1 week under circumstances involving treachery, assault and possible drug overdose. This case is unique as it involved two autopsies of the deceased by two different medical examiners who reached opposing conclusions. The first autopsy was performed about 10 days after death. The second autopsy was performed after an exhumation approximately 2 years after burial. Evidence collected at the crime scene included blood samples from which DNA was extracted and analysed, fingerprints and clothing containing dried body fluids. The conclusion of the first autopsy was accidental death due to cocaine toxicity; the conclusion of the second autopsy was death due to homicide given the totality of evidence. Suspects 1 and 2 were linked to the death of the victim by physical evidence and suspect 3 was linked by testimony. Suspect 1 received life in prison, and suspects 2 and 3 received 45 and 20 years in prison, respectively. This case indicates that cocaine toxicity is difficult to determine in putrefied tissue and that exhumations can be important in collecting forensic information. It further reveals that the combined findings of medical examiners, even though contradictory, are useful in determining the circumstances leading to death in criminal justice. Thus, this report demonstrates that such criminal circumstances require comparative forensic review and, in such cases, scientific conclusions can be difficult.

  15. A method for evaluating basement exhumation histories from closure age distributions of detrital minerals

    Energy Technology Data Exchange (ETDEWEB)

    Lovera, Oscar M. [Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles (United States); Grove, Marty [Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles (United States); Kimbrough, David L. [Department of Geological Sciences, San Diego State University, San Diego, California (United States); Abbott, Patrick L. [Department of Geological Sciences, San Diego State University, San Diego, California (United States)


    We have developed a two-dimensional, thermokinetic model that predicts the closure age distributions of detrital minerals from pervasively intruded and differentially exhumed basement. Using this model, we outline a method to determine the denudation history of orogenic regions on the basis of closure age distributions in synorogenic to postorogenic forearc strata. At relatively high mean denudation rates of 0.5 km m.y.-1 sustained over millions of years, magmatic heating events have minimal influence upon the age distributions of detrital minerals such as K-feldspar that are moderately retentive of radiogenic Ar. At lower rates, however, the effects of batholith emplacement may be substantial. We have applied the approach to detrital K-feldspars from forearc strata derived from the deeply denuded Peninsular Ranges batholith (PRB). Agreement of the denudation history deduced from the detrital K-feldspar data with thermochronologic constraints from exposed PRB basement lead us to conclude that exhumation histories of magmatic arcs should be decipherable solely from closure age distributions of detrital minerals whose depositional age is known. (c) 1999 American Geophysical Union.

  16. Exhumation history of the Tatry Mountains, Western Carpathians, constrained by low-temperature thermochronology (United States)

    Śmigielski, M.; Sinclair, H. D.; Stuart, F. M.; Persano, C.; Krzywiec, P.


    This study tests alternative models for the growth of the Tatry Mountains (Central Western Carpathians) by the application of low-temperature thermochronology. Zircon (U + Th)/He ages from the north of the range are mostly between 48 and 37 Ma and indicate cooling prior to the onset of fore-arc sedimentation in the region (42-39 Ma). In contrast, zircon (U + Th)/He ages in the south of the range are around 22 Ma. Apatite fission track ages across the sampled sites range from 20 to 15 Ma. Apatite (U + Th)/He ages range from 18 to 14 Ma with little variation with elevation or horizontal location. Based on thermal modeling and tectonic reconstructions, these Miocene ages are interpreted as cooling in the hanging wall of a northward dipping thrust ramp in the current location of the sub-Tatric fault with cooling rates of ~20°C/Myr at ~22-14 Ma. Modeled cooling histories require an abrupt deceleration in cooling after ~14 Ma to Carpathians and is synchronous with the transition of the Pannonian Basin from a syn-rift to a postrift stage and with termination of N-S compression in the northern part of the Central Western Carpathians. Overall, the timing of shortening and exhumation is synchronous with the formation of the Outer Carpathian orogen and so the Miocene exhumation of the Tatry records retrovergent thrusting at the northern margin of the Alcapa microplate.

  17. From nappe stacking to exhumation: Cretaceous tectonics in the Apuseni Mountains (Romania) (United States)

    Reiser, Martin Kaspar; Schuster, Ralf; Spikings, Richard; Tropper, Peter; Fügenschuh, Bernhard


    New Ar-Ar muscovite and Rb-Sr biotite age data in combination with structural analyses from the Apuseni Mountains provide new constraints on the timing and kinematics of deformation during the Cretaceous. Time-temperature paths from the structurally highest basement nappe of the Apuseni Mountains in combination with sedimentary data indicate exhumation and a position close to the surface after the Late Jurassic emplacement of the South Apuseni Ophiolites. Early Cretaceous Ar-Ar muscovite ages from structurally lower parts in the Biharia Nappe System (Dacia Mega-Unit) show cooling from medium-grade conditions. NE-SW-trending stretching lineation and associated kinematic indicators of this deformation phase (D1) are overprinted by top-NW-directed thrusting during D2. An Albian to Turonian age (110-90 Ma) is proposed for the main deformation (D2) that formed the present-day geometry of the nappe stack and led to a pervasive retrograde greenschist-facies overprint. Thermochronological and structural data from the Bihor Unit (Tisza Mega-Unit) allowed to establish E-directed differential exhumation during Early-Late Cretaceous times (D3.1). Brittle detachment faulting (D3.2) and the deposition of syn-extensional sediments indicate general uplift and partial surface exposure during the Late Cretaceous. Brittle conditions persist during the latest Cretaceous compressional overprint (D4).


    Institute of Scientific and Technical Information of China (English)

    吕红华; 王玮; 常远; 周祖翼


    In response to the India-Asia collision during Cenozoic times,the Tian Shan range has been tectonically reactivated and intensely uplifted.Many previous studies have focused on the history of uplift and exhumation of the Tian Shan during the Cenozoic based on low-temperature thermochronology,magnetostratigraphy and syntectonic deposits,sedimentology,and rock magnetism.However,the divergent opinions still exist.Here we also employ apatite fission-track analysis on rock samples from a transect along the Urüimqi-Korla road crossing the eastern part of the Tian Shan in order to better understand the spatial difference in the exhumation history of the Tian Shah range.In the field,we selected sixteen rock samples (WK1 ~ WK16) along the Road.The samples WK6 ~ WK10 and WK12 ~ WK15 were performed for all the analytical procedures of apatite fission track,which were mainly from the segment of the Road south of Shenglidaban.The other samples(WK1 ~ WK5,WK11,and WK16)were not further analyzed due to the following reasons:(1) there are not enough apatite grains for sample preparation,or(2) there is any suitable apatite grains for fission track statistics.In the lab,we obtained the AFT data such as confined track length,Dpar(diameter of etched spontaneous fission tracks measured parallel to the crystallographic C-axis),track angle to the crystallographic C-axis.Our fission-track data show that confined track length ranges from 12.8 ~ 14.1 μm with standard deviation of 1.41 ~ 1.75 μm,and that Dpar is 1.57 μm to 2.03 μm.AFT ages span 90 ~ 50Ma except for sample WK6 with the age of ca.158Ma.The positive correlation exists between these AFT age data and the corresponding elevations.The thermal modeling results show that the sampled part of the Tian Shan range has experienced two stages of exhumation during Cenozoic times,i.e.,slow exhumation before ca.20±5Ma followed by subsequent rapid exhumation,with the exhumation rates of ca.10 ~30m/Ma and ca.70 ~160m

  19. Kinematics of post-orogenic extension and exhumation of the Taku Schist, NE Peninsular Malaysia (United States)

    Md Ali, M. A.; Willingshofer, E.; Matenco, L.; Francois, T.; Daanen, T. P.; Ng, T. F.; Taib, N. I.; Shuib, M. K.


    Recent studies imply that the formation and evolution of many SE Asian basins was driven by extensional detachments or systems of low-angle normal faults that created significant crustal exhumation in their footwalls. In this context, the architecture of the Triassic Indosinian orogen presently exposed in Peninsular Malaysia is compatible with significant extension post-dating the orogenic event. In this study we performed a kinematic analysis based on fieldwork and microstructural observations in the Taku Schist, Kemahang granite and the surrounding Gua Musang sediments of northern Peninsular Malaysia in order to shed light on processes related to the build-up and subsequent demise of the Indosinian orogen. The first three phases of deformation were related to an overall period of E-W oriented contraction and burial metamorphism. These phases of deformation are characterized by isoclinal folding with flat lying axial plane cleavages (D1), asymmetrical folding, top-to-the-W-SW shearing (D2) and upright folding (D3). All are in general agreement with observations of the previously inferred Permo-Triassic Indosinian orogeny. During these times, the Taku Schist, a sequence of Paleozoic clastic sediments with mafic intercalations was metamorphosed to amphibolite facies. These rocks are most likely equivalent to the ones exposed in the Bentong-Raub suture zone. Structural relations suggest that the Triassic Kemahang pluton is syn-kinematic, which provides important constraints for the timing of these contractional events. We demonstrate that the overall shortening was followed by a hitherto undescribed extension in NW-SE direction resulting in the formation of a large-scale detachment, the Taku detachment, in northern Peninsular Malaysia. Extension probably reactivated the former subduction plane as a detachment and exhumed previously buried and metamorphosed rocks of similar lithological composition to the neighboring Bentong-Raub suture zone. Such a mechanism is

  20. Late Neogene exhumation of the Piceance basin, N.W. Colorado, USA: Integrated analysis of multiple thermochronometers and subsidence modeling (United States)

    Vernon, A. J.; Kendall, J. J.; Becker, T. P.; Patterson, P. E.; Reiners, P. W.; Kapp, J.


    The retrograde history of sedimentary basins is often poorly constrained by the study of subsidence, compaction, and thermal diffusion models. As part of industry/academic collaborative research on the fundamental processes active in convergent tectonics we combined multiple paleothermometers, paleobarometers, and thermochronometers on deep borehole samples with modern heat flow measurements to provide powerful constraint for estimating the exhumation history in an area. The Piceance basin (N.W. Colorado) lies east of the leading edge of the Cretaceous to early Eocene Sevier thrust belt, and is flanked by several basement-involved structures (Douglas Creek arch, White River dome, Uinta uplift, White River uplift) that exhibit growth from the Maastrichtian through the late Eocene. The youngest preserved strata within the Piceance basin are within the early Oligocene Uinta Formation, although there are deposits as young as Miocene locally preserved in the region that may have also capped the basin. The timing of uplift, river incision, and plateau-scale exhumation within this region fits into the larger context of the evolution of the Colorado River drainage system. A series of core, cutting, and surface samples were compiled to develop a synthetic well (or vertical section) of over 5000 m. Samples were collected from stratigraphic intervals ranging from the Jurassic to the Eocene and analyzed for apatite and zircon U-Th/He ages, as well as apatite fission track length distributions and ages. As the exhumation model was the unconstrained parameter, the timing and magnitude of the cooling associated with such an event was systematically varied. Thermal histories of each sampled interval were extracted from differing exhumation scenarios in the Piceance basin model (which tracks the temperature and pressure evolution during burial and denudation) and forward modeled using HeFTy. The combined use of several thermochronometers (apatite and zircon U-Th/He, apatite fission

  1. Neogene Uplift and Exhumation of Plutonic Bodies in the Beni Bou Ifrour Massif (Nador, northeastern Morocco) (United States)

    Lebret, Noëmie; Jolivet, Laurent; Branquet, Yannick; Bourdier, Jean-Louis; Jolivet, Marc; Marcoux, Eric


    In Neogene times, the whole Mediterranean Sea was the center of an intense magmatic activity. This post-collisional magmatism produced a large amount of volcanic edifices through the Alpine belts, together with some intrusives. These plutonic bodies can be associated with skarn-type mineralization, well-known in Elba Island or Serifos Island (Cyclades), where they are generally exhumed by detachment faults. In Morocco, the plutons hosted by the Beni Bou Ifrour massif are connected to the biggest skarn-type iron concentrations of the country (production > 60 Mt, reserves ≈ 25 Mt). The purpose of this work is to explain the late uplift of this massif and subsequent exhumation of the intrusives. As a final product of the Africa-Eurasia plate convergence since ca. 70 Ma, the Rif Mountains constitute the westernmost segment of the Mediterranean Alpine belts. In the oriental part of this range, volcanic summits and Paleozoic to Mesozoic massifs outcrop in the surrounding Mio-Pliocene plains. The Beni Bou Ifrour massif, in the Nador province, consists in a dome-shaped folded Mesozoic series (Domerian to Barremian) affected by a slight epizonal regional metamorphism (ca. 14-12 Ma), dislocated by Neogene NE-SW faults and eventually sealed by upper Miocene transgressive sediments. The hosted intrusives (7.58 ± 0.03 Ma; Duggen et al., 2005) are the plutonic equivalents to the potassic calc-alkaline lavas (andesites mainly) from the surrounding "satellite" volcanic massifs. They turn out to stand in higher topographic position than the younger shoshonitic lavas of the neighboring Gourougou stratovolcano (6.12 ± 0.01 Ma; Duggen et al., 2005). Previous studies have attributed this uplift to the action of normal faults (pull-apart basins; Guillemin & Houzay, 1982), thrusting (Kerchaoui, 1985; 1995) or even of a caldeira resurgence (El Bakkali, 1995). To discriminate against those exhumation mechanisms, field work has been performed, coming along with new cross-sections to

  2. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars. (United States)

    Grotzinger, J P; Gupta, S; Malin, M C; Rubin, D M; Schieber, J; Siebach, K; Sumner, D Y; Stack, K M; Vasavada, A R; Arvidson, R E; Calef, F; Edgar, L; Fischer, W F; Grant, J A; Griffes, J; Kah, L C; Lamb, M P; Lewis, K W; Mangold, N; Minitti, M E; Palucis, M; Rice, M; Williams, R M E; Yingst, R A; Blake, D; Blaney, D; Conrad, P; Crisp, J; Dietrich, W E; Dromart, G; Edgett, K S; Ewing, R C; Gellert, R; Hurowitz, J A; Kocurek, G; Mahaffy, P; McBride, M J; McLennan, S M; Mischna, M; Ming, D; Milliken, R; Newsom, H; Oehler, D; Parker, T J; Vaniman, D; Wiens, R C; Wilson, S A


    The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

  3. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars (United States)

    Grotzinger, J.P.; Gupta, S.; Malin, M.C.; Rubin, D.M.; Schieber, J.; Siebach, K.; Sumner, D.Y.; Stack, K.M.; Vasavada, A.R.; Arvidson, R.E.; Calef, F.; Edgar, Lauren; Fischer, W.F.; Grant, J.A.; Griffes, J.L.; Kah, L.C.; Lamb, M.P.; Lewis, K.W.; Mangold, N.; Minitti, M.E.; Palucis, M.C.; Rice, M.; Williams, R.M.E.; Yingst, R.A.; Blake, D.; Blaney, D.; Conrad, P.; Crisp, J.A.; Dietrich, W.E.; Dromart, G.; Edgett, K.S.; Ewing, R.C.; Gellert, R.; Hurowitz, J.A.; Kocurek, G.; Mahaffy, P.G.; McBride, M.J.; McLennan, S.M.; Mischna, M.A.; Ming, D.; Milliken, R.E.; Newsom, H.; Oehler, D.; Parker, T.J.; Vaniman, D.; Wiens, R.C.; Wilson, S.A.


    The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

  4. Middle Miocene Hotspot-Related Uplift, Exhumation, and Extension north of the Snake River Plain: Evidence from Apatite (U-Th)/He Thermochronology (United States)

    Foster, D. A.; Vogl, J.; Min, K. K.; Bricker, A.; Gelato, P. W.


    Passage of North America over the Yellowstone hotspot has had a profound influence on the topography of the northern Rocky Mountains. One of the most prominent topographic features is the Yellowstone crescent of high topography, which comprises two elevated shoulders bounding the eastern Snake River Plain (SRP) and converging at a topographic swell centered on the Yellowstone region. Kilometer-scale erosion has occurred locally within the topographic crescent, but it is unclear if rock exhumation is due to surface uplift surrounding the propagating hot spot, subsidence of the Snake River Plain after passage of the hot spot, or relief initiated by extension in the Northern Basin and Range Province. We have applied (U-Th/He) apatite (AHe) thermochronology to the Pioneer-Boulder Mountains (PBM) on the northern flank of the SRP, and the southern Beartooth Mountains (BM) directly north of the modern Yellowstone caldera, to constrain the timing, rates, and spatial distribution of exhumation. AHe ages from the PBM indicate that >2-3 km of exhumation occurred in the core of this topographic culmination since ~11 Ma. Age-elevation relationships suggest an exhumation rate of ~0.3 mm/yr between ~11 and 8 Ma. Eocene Challis volcanic rocks are extensively preserved and Eocene topographic highs are locally preserved to the north and south of the PBM, indicating minimal erosion adjacent to the PBM culmination. Spatial patterns of both exhumation and topography indicate that faulting was not the primary control on uplift and exhumation. Regional exhumation at 11-8 Ma was synchronous with silicic eruptions from the ~10.3 Ma Picabo volcanic field located immediately to the south and with S-tilting of the southern flank of the PBM that is likely the result of loading of the ESRP by mid-crustal mafic intrusions. AHe data from Archean rocks of the southern BM reveal Miocene-Pliocene cooling ages and include samples as young as ~2-6 Ma. Discordant single grain ages in samples with

  5. Cooling and Exhumation of the Coastal Batholith in the Peruvian Andes (5-12°S) (United States)

    Michalak, M.; Hall, S. R.; Farber, D.; Hourigan, J. K.; Audin, L.


    The South American Andes exhibit strong morphological differences along strike, shaped by a combination of tectonic forces and surface processes. In the central Peruvian Andes (~12°S) a major morphological transition occurs; to the north, the spines of the Western and Eastern Cordilleras come together into a relatively narrow configuration of high topography. In Southern Peru, the region of high topography widens, where the Western and Eastern Cordilleras flank the broad, Altiplano plateau. Despite this morphological change, the Mesozoic-early Cenozoic Coastal Batholith outcrops continuously from 0°-18°S along the western margin of the Peruvian Andes, emplaced along a trench-parallel marginal basin in the Mesozoic. The Coastal Batholith is an ideal geologic setting to investigate potential differences in rock exhumation and cooling histories along the western margin of Peru. While the cooling history of the southern Coastal Batholith has been previously used to estimate timing and magnitude of rock exhumation in Southern Peru, north of 12°S it is poorly constrained. We present 16 zircon and 7 apatite (U-Th)/He mean-ages from three sites, across seven degrees of latitude (5°S to 12°S). In general, ZHe and AHe ages capture two stages of cooling, Oligocene-to-mid-Miocene and mid-to-late Miocene, respectively. We model time-temperature histories of samples with paired AHe and ZHe ages using a Monte-Carlo inversion of HeFTy® (Ketcham, 2005); best fit time-temperature pathways show cooling rates ranging from ~2-24°C/my, where fastest cooling rates are generally observed in the mid-Miocene. To estimate exhumation rates, we apply a simple thermal model to account for nonuniform geothermal gradients expected in a trench-arc setting. Exhumation rates range from ~0.2mm/yr in the north, to 0.4-0.7mm/yr in the south, and rates increase orogenward, where mean elevation is highest. These results, particularly the predominance of Miocene ZHe and AHe data, and the younging

  6. Rheological Heterogeneity Along the Deep Subduction Interface: Insights from Exhumed HP Metamorphic Rocks Exposed on Syros Island, Greece (United States)

    Kotowski, A. J.; Behr, W. M.; Stockli, D. F.; Ashley, K. T.


    Rheological properties of subduction interface shear zones control several aspects of subduction zone dynamics, including shear tractions along the plate interface, rates and amounts of exhumation, and depths and styles of seismicity. We document the rheological properties of a deep subduction interface using exhumed eclogite and blueschist-facies rocks from Syros Island, Greece. These rocks were subducted to ~60 km depth during the Eocene, were exhumed part way along the top of the subducting slab, and were then exhumed to upper-crustal levels beneath Miocene detachment faults. Localization of strain during exhumation allowed prograde fabrics to be preserved. The PT conditions (400-550°C, 12-16kb) of these fabrics are comparable to conditions of episodic tremor and slow slip (ETS) observed in some modern subduction zones, including Cascadia. Two types of prograde fabrics were distinguished after analyzing macro-scale distributions of strain and microphysical mechanisms of creep in metamafic rocks. Type 1 fabrics contain eclogite pods boudinaged within a blueschist matrix. The eclogites show brittle deformation with cross-cutting veins containing high-pressure minerals. Deformation in matrix blueschists is accommodated by rigid rotation of amphibole and diffusion creep in plagioclase. Type 2 fabrics contain blueschists and eclogites that are isoclinally folded at similar wavelengths, thus are approximately isoviscous. Deformation is again accommodated by diffusion creep in blueschists, but by dislocation creep of omphacite in eclogites. These deformation types characterizing boudin-matrix and isoviscous rheologies of blueschist-eclogite assemblages appear to reflect varying amounts of finite strain, but work is in progress to determine whether they also record different PT conditions. The transition from Type 1 to 2 fabrics represents a significant change in bulk viscosity and seismic anisotropy, and may correspond to a transition from ETS-type behavior

  7. New Thermochronologic Data Constraining the Exhumation History of the Pangong Range, Ladakh, NW India (United States)

    Bohon, W.; Tripathy, A.; Hodges, K.; Arrowsmith, R.; Van Soest, M. C.


    Major transcurrent fault systems have played a fundamental role in the late Cenozoic evolution of the Himalayan-Tibetan orogenic system. One of the most dramatic of these is the NW-SE striking, dextral-oblique Karakoram fault system (KFS), which effectively serves as the SW boundary of the Tibetan Plateau. In the Ladakh region of NW India, the fault system bifurcates into 2 fault strands bounding the Pangong Range (PR), a lozenge-shaped region of high elevation that is commonly regarded as a transpressional uplift. We are studying the partitioning of slip over time between shortening and translational components during transpression along both KFS strands. An important aspect of this work is a study of the differential exhumation history of the PR relative to two other high elevation regions to the north and south: the Karakoram Range (KR) and the Ladakh Range (LR), respectively. Although a variety of thermochronometric data will be reported for the LR, PR, and KR in our presentation, we focus here on (U-Th)/He zircon (ZHe) data for the KR and LR. Four published ZHe dates for the northern margin of the LR (Kirstein et al., 2009, Geological Society of London, special pub.) range from 12.9 ± 2.0 Ma to 19.2 ± 3.0 Ma (2 σ) with a rough correlation of older dates at higher elevations. Our new dates for samples collected nearer to the SW strand of the KFS are substantially younger: 7.5 ± 0.12 Ma. It is unclear if the combined datasets are indicative of protracted cooling of the northern part of the LR during rotational exhumation of the LR to the south, as postulated by Kirstein et al., or if the ca. 7.5 Ma dates represent local resetting during KFS activity. Interestingly, detrital ZHe data for modern sands from large catchments that drain the KR range to the north of the NE strand of the KFS indicate cooling of the KR below the nominal bulk closure temperature of the ZHe system (ca. 190C) within a narrow time range of 5.5-7.8 Ma. This range includes the ZHe cooling

  8. Thermal and exhumation history of the Coastal Cordillera arc of northern Chile revealed by thermochronological dating (United States)

    Juez-Larré, Joaquim; Kukowski, Nina; Dunai, Tibor J.; Hartley, Adrian J.; Andriessen, Paul A. M.


    The thermal and erosional history of convergent plate boundaries is important for understanding the links between subduction, arc magmatism, genesis of ore deposits, topography and climate of orogenic belts. Unlike the continent-continent collision that formed many of the largest orogenic belts known today, the Central Andes of South America is a unique case where an oceanic-continent collision has given rise to the Earth's longest and second tallest orogenic belt. Over the last thirty years a plethora of models have been suggested in an attempt to explain how a plateau-type orogen formed at the leading edge of western South America. In the Central Andes most research have focussed attention on the study of the evolution of the arc and backarc, since continuous subduction erosion of the forearc has left little trace of the interplate dynamics that initiated the orogenic belt. In this article, we present a new insight into the thermal and exhumation history of the forearc along the Coastal Cordillera of northern Chile based on biotite K-Ar, apatite fission-track, and apatite/zircon (U-Th)/He dating. We collected diorite samples in a 2 km thick crustal section at the coastal cliff (~ 22°S), and a sea level isoelevation profile between 21 and 27°S. Results from all three dating methods show that the cooling of Coastal Cordillera took place shortly after emplacement during a period of rifting in Jurassic times. Cooling took place in two episodes, mainly in Late Jurassic-Early Cretaceous (~ 118-152 Ma) but also during Late Cretaceous (60-80 Ma) due to the resumption of compression, rift closure, arc uplift, exhumation, eastward migration of magmatic arc activity, and thermal relaxation. The youngest apatite (U-Th)/He ages reveal a cooling event, never reported previously, between 40 and 50 Ma (Eocene). This thermal event affected a > 500 km long and > 1 km thick section of the Coastal Cordillera in northern Chile. Rock cooling recorded in the Eocene cannot be

  9. Kinematics of syn- and post-exhumational shear zones at Lago di Cignana (Western Alps, Italy): constraints on the exhumation of Zermatt-Saas (ultra)high-pressure rocks and deformation along the Combin Fault and Dent Blanche Basal Thrust (United States)

    Kirst, Frederik; Leiss, Bernd


    Kinematic analyses of shear zones at Lago di Cignana in the Italian Western Alps were used to constrain the structural evolution of units from the Piemont-Ligurian oceanic realm (Zermatt-Saas and Combin zones) and the Adriatic continental margin (Dent Blanche nappe) during Palaeogene syn- and post-exhumational deformation. Exhumation of Zermatt-Saas (U)HP rocks to approximately lower crustal levels at ca. 39 Ma occurred during normal-sense top-(S)E shearing under epidote-amphibolite-facies conditions. Juxtaposition with the overlying Combin zone along the Combin Fault at mid-crustal levels occurred during greenschist-facies normal-sense top-SE shearing at ca. 38 Ma. The scarcity of top-SE kinematic indicators in the hanging wall of the Combin Fault probably resulted from strain localization along the uppermost Zermatt-Saas zone and obliteration by subsequent deformation. A phase of dominant pure shear deformation around 35 Ma affected units in the direct footwall and hanging wall of the Combin Fault. It is interpreted to reflect NW-SE crustal elongation during updoming of the nappe stack as a result of underthrusting of European continental margin units and the onset of continental collision. This phase was partly accompanied and followed by ductile bulk top-NW shearing, especially at higher structural levels, which transitioned into semi-ductile to brittle normal-sense top-NW deformation due to Vanzone phase folding from ca. 32 Ma onwards. Our structural observations suggest that syn-exhumational deformation is partly preserved within units and shear zones exposed at Lago di Cignana but also that the Combin Fault and Dent Blanche Basal Thrust experienced significant post-exhumational deformation reworking and overprinting earlier structures.

  10. Subduction / exhumation dynamics: Petrochronology in the Glacier-Rafray slice (Western Alps, Italy) (United States)

    Burn, Marco; Lanari, Pierre; Engi, Martin


    allochthons; one would expect these to have entered the subduction zone together with the Piemonte oceanic units. Yet all high-P ages reported for the Piemonte oceanic units are around 40 Ma. We propose that the Glacier-Rafray slice experienced subduction together with Sesia units and may have been juxtaposed on the Piemont-Ligurian-Ocean units during Eocene exhumation. Strain associated with this juxtaposition may have triggered growth of the second allanite. Joint exhumation of the oceanic units and the Glacier-Rafray klippe followed at retrograde T.

  11. Constraining Early Cenozoic exhumation of the British Isles with vertical profile modelling (United States)

    Doepke, Daniel; Cogné, Nathan; Chew, David


    Despite decades of research is the Early Cenozoic exhumation history of Ireland and Britain still poorly understood and subject to contentious debate (e.g., Davis et al., 2012 and subsequent comments). One reason for this debate is the difficultly of constraining the evolution of onshore parts of the British Isles in both time and space. The paucity of Mesozoic and Cenozoic onshore outcrops makes direct analysis of this time span difficult. Furthermore, Ireland and Britain are situated at a passive margin, where the amount of post-rift exhumation is generally very low. Classical thermochronological tools are therefore near the edge of their resolution and make precise dating of post-rift cooling events challenging. In this study we used the established apatite fission track and (U-Th-Sm)/He techniques, but took advantage of the vertical profile approach of Gallagher et al. (2005) implemented in the QTQt modelling package (Gallagher, 2012), to better constrain the thermal histories. This method allowed us to define the geographical extent of a Late Cretaceous - Early Tertiary cooling event and to show that it was centered around the Irish Sea. Thus, we argue that this cooling event is linked to the underplating of hot material below the crust centered on the Irish Sea (Jones et al., 2002; Al-Kindi et al., 2003), and demonstrate that such conclusion would have been harder, if not impossible, to draw by modelling the samples individually without the use of the vertical profile approach. References Al-Kindi, S., White, N., Sinha, M., England, R., and Tiley, R., 2003, Crustal trace of a hot convective sheet: Geology, v. 31, no. 3, p. 207-210. Davis, M.W., White, N.J., Priestley, K.F., Baptie, B.J., and Tilmann, F.J., 2012, Crustal structure of the British Isles and its epeirogenic consequences: Geophysical Journal International, v. 190, no. 2, p. 705-725. Jones, S.M., White, N., Clarke, B.J., Rowley, E., and Gallagher, K., 2002, Present and past influence of the Iceland

  12. UHP-UHT peak conditions and near-adiabatic exhumation path of diamond-bearing garnet-clinopyroxene rocks from the Eger Crystalline Complex, North Bohemian Massif (United States)

    Haifler, Jakub; Kotková, Jana


    -clinopyroxene rocks from North Bohemia are UHP-UHT rocks which were extensively overprinted under HP granulite-facies conditions during rapid exhumation along a near-adiabatic P-T path. The UHT peak and UHT-HT exhumation distinguish this area from the other UHP terrains worldwide. We demonstrate that Ti-in-zircon thermometry can provide robust temperature estimates in the rocks exhumed at HT, where the UHP-UHT mineral assemblage has not been preserved. In addition, the calculated UHP-UHT conditions are similar to those determined for the associated garnet peridotites, providing evidence for juxtaposition of these crustal and mantle rocks during deep Variscan subduction.

  13. Coupled micro-faulting and pressure solution creep overprinted on quartz schist deformed by intracrystalline plasticity during exhumation of the Sambagawa metamorphic rocks, southwest Japan


    Takeshita, Toru; El-Fakharani, Abdel-Hamid


    In the Sambagawa schist, southwest Japan, while ductile deformation pervasively occurred at D1 phase during exhumation, low-angle normal faulting was locally intensive at D2 phase under the conditions of frictional-viscous transition of quartz (c. 300 ℃) during further exhumation into the upper crustal level. Accordingly, the formation of D2 shear bands was overprinted on type I crossed girdle quartz c-axis fabrics and microstructures formed by intracrystalline plasticity at D1 phase in some ...

  14. Cenozoic burial and exhumation history of the Kangerlussuaq area, East Greenland, revealed by new apatite fission-track data (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Nielsen, Troels F.


    The Kangerlussuaq area in East Greenland (c. 68°N) has witnessed a complex geological development during the Cenozoic. The Skaergaard intrusion and the up to 5 km thick flood basalts formed during a short period around 55 Ma, and subsequently numerous intrusive bodies were emplaced, primarily during the Eocene. Relatively little is known about the geological history over the last 35 Myr, other than that an outlier of Middle Miocene lavas is located in the area at an elevation of c. 2.7 km. At the present-day, the area is deeply eroded and magmatic bodies that were emplaced deeply in the crust, are now exposed at the surface, but at the same time, the area has a significant elevation and even hosts the highest peak in Greenland, Gunbjørn Fjeld, 3.7 km above sea level. To unravel the history of burial and exhumation in the Kangerlussuaq area, new apatite fission-track analysis (AFTA) data has been acquired for 75 rock samples. Preliminary results show that the area has been subject to several phases of cooling since burial under the Palaeogene flood basalts. Phases of regional cooling along the coast that occurred at the Eocene-Oligocene transition and in the late Neogene are interpreted to be due to uplift and exhumation. Cooling events of local extent that occurred in the Eocene, Oligocene and Miocene are interpreted to be related to both exhumation and to circulating hot fluids. Results from samples along vertical transects reveal details of the protracted exhumation history, and that the present topography was formed during the late Neogene.

  15. Lisa K. Perdigao. From Modernist Entombment to Postmodernist Exhumation Dead Bodies in Twentieth-Century American Fiction.

    Directory of Open Access Journals (Sweden)

    Ben Robbins


    Full Text Available Lisa K. Perdigao’s monograph titled From Modernist Entombment to Postmodernist Exhumation, seeks to offer a comprehensive study of the corpse as represented in American fiction of the twentieth century. Perdigao explores how novelists from a range of time periods and traditions use dead bodies as a device that is revealing of the wider formal ambitions of narrative. In her introduction, Perdigao sets out the theoretical framework on which her study is based. She draws on poststructuralist the...

  16. Post-collisional magmatism: Consequences of UHPM terrane exhumation and orogen collapse, N. Qaidam UHPM belt, NW China (United States)

    Wang, Mengjue; Song, Shuguang; Niu, Yaoling; Su, Li


    Exhumation of subducted slabs and extensional collapse of orogens are the main tectonic processes in ancient and modern continental collisional zones. Magmatism during these two processes may play important roles in understanding reworking and growth of the continental crust. We report here that a series of plutonic magmas, including intrusions of two-mica granite, tonalite, granodiorite, biotite monzogranite, porphyritic biotite granite and diorite, as well as contemporaneous mafic dykes, have been recognized in Dulan eclogite-bearing terrane, the North Qaidam ultra-high pressure metamorphic (UHPM) belt. The magmatism represented by these plutons is temporally ~ 20-30 million years (Mys) younger than the UHPM age, lasting for ~ 40 Mys and derived from different sources with different mechanisms. The magmatism was initiated by exhumation of UHPM terranes during which strongly-peraluminous two-mica granite and metaluminous tonalite were produced respectively by decompression melting of the exhumed UHPM upper and lower continental crust, respectively. The genesis of mafic magmatic enclave (MME)-hosting granodiorite with a clear hybrid signature and coeval biotite monzogranite reflected the upwelling of asthenospheric mantle by extension of lithosphere during the orogen collapse. It was induced by detachment of the subducted lithospheric mantle, which then brought heat and mantle material into continental crust and triggered the partial melting of the exhumed UHPM continental crust, and gave rise to mixing of crustal and mantle melts. Porphyritic biotite granite reflects a late melting event of continental crust. Diorite marked by high magnesium content represents mantle melts with slight crustal contamination, which implies that the orogen has been unrooted and collapsed completely. The post-collisional magmatism of the North Qaidam belt provides an improved understanding for the late thermal and tectonic evolution of a UHPM continental collision zone.

  17. Buoyancy-Driven Fluid Flow Generated by Bacterial Metabolism and its Proposed Relationship to Increased Bacterial Growth in Space (United States)


    Escherichia coli. Carnegie Institute, Washington, DC, p. 184, 1955. Robinson, T. P., Ocio , M. J., Kaloti, A., et al. The effect of the growth...environment on the lag phase of Listeria monocytogenes. Int. J. Food Microbiol. 44, 83-92, 1998. Robinson, T. P., Ocio , M. J. Kaloti, A., et al. The

  18. Buoyancy-driven mixing of fluids in a confined geometry; Melange gravitationnel de fluides en geometrie confinee

    Energy Technology Data Exchange (ETDEWEB)

    Hallez, Y


    The present work based on Direct Numerical Simulations is devoted to the study of mixing between two miscible fluids of different densities. The movement of these fluids is induced by buoyancy. Three geometries are considered: a cylindrical tube, a square channel and a plane two-dimensional flow. For cylindrical tubes, the results of numerical simulations fully confirm previous experimental findings by Seon et al., especially regarding the existence of three different flow regimes, depending on the tilt angle. The comparison of the various geometries shows that tridimensional flows in tubes or channels are similar, whereas the two-dimensional model fails to give reliable information about real 3D flows, either from a quantitative point of view or for a phenomenological understanding. A peculiar attention is put on a joint analysis of the concentration and vorticity fields and allows us to explain several subtle aspects of the mixing dynamics. (author)

  19. Analytical and experimental study of instabilities in buoyancy-driven convection in porous media. Progress report, August 1991--April 1992

    Energy Technology Data Exchange (ETDEWEB)

    Georgiadis, J.G.; Behringer, R.; Johnson, G.A.


    During the second year of support under the DOE grant, significant progress was made in two directions: (1) Visualization of structure and tow field in randomly packed beds via Magnetic Resonance Imaging, and (2) Shadowgraphic visualization of natural convection in porous systems. This report describes the activities in detail, cite publications which resulted from this project, and conclude with plans for the last phase of the experimental investigation.

  20. Buoyancy-Driven Radiative Unsteady Magnetohydrodynamic Heat Transfer over a Stretching Sheet with non-Uniform Heat Source/sink

    Directory of Open Access Journals (Sweden)

    Dulal Pal


    Full Text Available In the present study an unsteady mixed convection boundary layer flow of an electrically conduct- ing fluid over an stretching permeable sheet in the presence of transverse magnetic field, thermal radiation and non-uniform heat source/sink effects is investigated. The unsteadiness in the flow and temperature fields is due to the time-dependent nature of the stretching velocity and the surface temperature. Both opposing and assisting flows are considered. The dimensionless governing or- dinary non-linear differential equations are solved numerically by applying shooting method using Runge-Kutta-Fehlberg method. The effects of unsteadiness parameter, buoyancy parameter, thermal radiation, Eckert number, Prandtl number and non-uniform heat source/sink parameter on the flow and heat transfer characteristics are thoroughly examined. Comparisons of the present results with previously published results for the steady case are found to be excellent.

  1. Exhumation research concerning the victims of political repressions in 1945-1956 in Poland: A new direction in forensic medicine. (United States)

    Szleszkowski, Lukasz; Thannhäuser, Agata; Szwagrzyk, Krzysztof; Konczewski, Paweł; Kawecki, Jerzy; Swiątek, Barbara


    In 2011 in Wroclaw (Poland), the bodies of 223 prisoners were exhumed, including the victims of political repressions and prosecutions in the period 1949-1954, during which people fighting for the independence of Poland were executed and buried in unidentified graves in various graveyards. It was the first exhumation conducted in Poland on such a large scale. The aim of the present publication is to describe the new direction in forensic medicine employed in these exhumations, which resulted from the new opportunities created by the opening of the state archives after the political transformation of 1989. The authors describe the difficulties they encountered during their exploration of prisoners' burial grounds. The graveyards included in the investigation bear the marks of an intentional policy of confusion and secret burial methods. First, significant disorder in the logical (based on time of death) sequence of burials was observed. This made identification difficult. A substantial time lapse between death and burial in each case, along with the unavailability of comparative data, limited the use of identification methods widely employed in forensic medicine. For this reason, initial analysis had to be based on observations and confirmations made by forensic medicine about the sequence of burials as compared to cemetery documentation. Situations such as this clearly call for the cooperation of historians, archaeologists, anthropologists and forensic pathologists. Political transformations in Eastern Europe in the 1990s gave rise to hopes of exchanging experiences in this type of research as conducted in other countries of the former Eastern Bloc.

  2. Short-lived polyphase deformation during crustal thickening and exhumation of a collisional orogen (Ribeira Belt, Brazil) (United States)

    Faleiros, F. M.; Campanha, G. A. C.; Pavan, M.; Almeida, V. V.; Rodrigues, S. W. O.; Araújo, B. P.


    The Ribeira Belt (Brazil) is a Neoproterozoic collisional-related feature that was located in a south-central position in West Gondwana. We present quantitative data on finite strain, flow vorticity and deformation temperatures for the Curitiba Terrane, a major segment of the southern Ribeira Belt. Six deformation phases (D1-D6) related with crustal thickening and exhumation were recognized. D1 and D2-related microstructures are preserved exclusively within porphyroblasts, in part grown during stages of high-pressure (∼9-12 kbar) isobaric heating after crustal thickening. D3 phase was active from peak metamorphism attained in contrasting crustal levels (810-400 °C), to the early stage of exhumation (500-400 °C), as indicated by petrological, microstructural and quartz c-axis fabric evidence. Kinematic vorticity results indicate that the SL3 mylonitic fabric resulted from a simple shear-dominated deformation related with westward thrusting. North-verging overturned D4 folds with E-W-trending subhorizontal axes derived from a pure shear-dominated deformation. Regional D5 open folds with subvertical axes and NNE-SSW-trending traces were produced by indentation tectonics. D6 phase comprises retrograde orogen-parallel transcurrent shear zones related with scape tectonics. Geochronological data indicate that D3-D6 phases occurred between 584 and 580 Ma, suggesting a fast exhumation rate of ∼8 mm/year for the deepest rocks from the southern Ribeira Belt.

  3. Exhumation of the Panama basement complex and basins: Implications for the closure of the Central American seaway (United States)

    Ramírez, Diego A.; Foster, David A.; Min, Kyoungwon; Montes, Camilo; Cardona, Agustín.; Sadove, Gephen


    The emergence of the Central American isthmus occurred episodically from Eocene to Pliocene time and was caused by a series of tectonic and volcanic processes. Results from zircon U-Pb geochronology, zircon (U-Th)/He (ZHe) and apatite (U-Th)/He (AHe) thermochronology, and zircon Lu-Hf isotopic data from sedimentary (sandstones and recent river sands) and plutonic rocks from the Azuero Peninsula and Central Panama document the exhumation and uplift history of the Panamanian basement complex. Our data support previous paleobotanical and thermochronological studies that suggest that by middle Eocene time some areas of Central Panama and Azuero Peninsula were exposed above sea level as a series of islands surrounded by shallow open marine waters. The Gatuncillo, Cobachón and Tonosí formations were deposited during this partial emergence. Transtension in the Oligocene-early Miocene produced various pull-apart basins (e.g., the Canal Basin) and local uplift that exhumed the Eocene strata (Gatuncillo and Cobachón formations). This event probably reduced circulation between the Pacific Ocean and the Caribbean Sea. The Tonosí Formation records late Miocene to Pleistocene cooling and exhumation, which may be related to uplift above the subducting Coiba Ridge. These results suggest that the emergence of the Isthmus of Panama followed a series of diachronous events that led to the final closure of the Central American seaway.

  4. Modelling of low-temperature exhumation rate in Dabie Mountain based on (U-Th)/He and fission-track thermochronological data

    Institute of Scientific and Technical Information of China (English)

    DING Ruxin; ZHOU Zuyi; XU Changhai; LIU Yuzhu; CHENG Hao; XU Fei


    While the high-temperature exhumation process in the Dabie Mountain has been well documented, the low-temperature exhumation of this area since Cretaceous, especially since Late Cretaceous, is relatively less studied. Low-temperature thermochronology provides one of the important approaches to solve this problem. Based on the data of fission track and (U-Th)/He analysis of apaptites and zircons from the granitoid and metamorphic rocks in the Dabie Mountain, this paper applies Mancktelow's and Braun's methods to estimating the exhumation rates and to drawing the regional differential exhumation pattern since Cretaceous, especially since Late Cretaceous by taking into consideration factors such as heat transport, heat advection, topography and heat production,which could influence geothermal field in the shallow crust. Since Cretaceous, the exhumation rate (0.08-0.10 km/Ma) in the region around Tiantangzhai and in the south of Tanlu fault zone is larger than the rate (0.04-0.07 km/Ma) in other areas of the Dabie Mountain. The regional differential exhumation pattern might be related to the push-up effect caused by differential strike-slip movement along NNE-trending faults.

  5. Detrital record of initial basement exhumation along the Laramide deformation front, southern Rocky Mountains (United States)

    Bush, Meredith A.; Horton, Brian K.; Murphy, Michael A.; Stockli, Daniel F.


    New geochronological constraints on upper crustal exhumation in the southern Rocky Mountains help delineate the latest Cretaceous-Paleogene history of drainage reorganization and landscape evolution during Laramide flat-slab subduction beneath western North America. Detrital zircon U-Pb results for the Raton basin of southern Colorado and northern New Mexico define the inception of coarse-grained siliciclastic sedimentation and a distinctive shift in provenance, from distal to proximal sources, that recorded shortening-related uplift and unroofing along the Laramide deformation front of the northern Sangre de Cristo Mountains. This Maastrichtian-early Paleocene ( 70-65 Ma) change—from distal foreland accumulation of sediment derived from the thin-skinned Cordilleran (Sevier) fold-thrust belt to coarse-grained sedimentation proximal to a Laramide basement block uplift—reflects cratonward (eastward) deformation advance and reorganization of drainage systems that supplied a large volume of Paleocene-lower Eocene sediments to the Gulf of Mexico. The timing of unroofing along the eastern deformation front is synchronous with basement-involved shortening across the interior of the Laramide province, suggesting abrupt wholesale uplift rather than a systematic inboard advance of deformation. The growth and infilling of broken foreland basins within the interior and margins of the Laramide province had a significant impact on continental-scale drainage systems, as several ponded/axial Laramide basins trapped large volumes of sediment and induced reorganization of major source-to-sink sediment pathways.

  6. In search of the Boston Strangler: genetic evidence from the exhumation of Mary Sullivan. (United States)

    Foran, David R; Starrs, James E


    The Boston Strangler was one of the United States' most notorious serial killers, raping and strangling with decorative ligatures thirteen woman in Boston during the early 1960s. Albert DeSalvo, never a suspect in the slayings, confessed in prison (where he was later murdered) to being the Boston Strangler, and the investigation largely ended. Mary Sullivan was the last victim of the Boston Strangler, found sexually assaulted and strangled in her Boston apartment in 1964. Recently, a team of forensic scientists undertook the exhumation and subsequent scientific analysis of Mary Sullivan's remains, in hope of finding consistencies or inconsistencies between DeSalvo's confessed description of the murder and any evidence left behind. Included in these analyses was extensive DNA testing of all UV fluorescent material associated with the body. The large majority of results were negative, however, fluorescent material located on the underwear and entwined in her pubic hair generated two human mitochondrial DNA sequences. Neither of these matched the victim nor members of the forensic team who worked on the evidence. Most importantly, neither DNA sequence could have originated from Albert DeSalvo.

  7. Long-term exhumation history of the Inner Mongolian Plateau constrained by apatite fission track analysis (United States)

    Li, Ke; Jolivet, Marc; Zhang, Zhicheng; Li, Jianfeng; Tang, Wenhao


    The Inner Mongolian Plateau, along the southeastern flank of the wider Mongolian Plateau, is a vast undulating surface ranging in elevation between 900 and 1500 m above sea level. The peculiar topography of this area is assumed to be closely related to its complex tectono-thermal evolution since Late Paleozoic. The lithospheric structure of the Plateau includes three continental blocks: the Mandula and the Bart Obo blocks form the southern margin of the Central Asian Orogenic Belt in that area, and to the south, the Plateau includes the northern margin of the North China Craton. Apatite fission track (AFT) ages and track length distributions from 13 basement outcrops situated in the main tectonic blocks forming the Inner Mongolian Plateau were determined in order to reconstruct its denudation history. The thermal histories inferred from these data imply multi-phased, differential exhumation/burying processes from the Late Paleozoic to the Early Cretaceous. This complex thermal history is largely related to the Early/Middle Triassic closure of the Paleo-Asian Ocean, the Jurassic closure of the Mongol-Okhotsk Ocean, and the Early Cretaceous orogenic collapse of the Mongol-Okhotsk belt. Finally, since Late Cretaceous, no further major tectonic movement occurred and the Inner Mongolian Plateau has been largely peneplained.

  8. Strain localization in shear zones during exhumation: a graphical approach to facies interpretation (United States)

    Cardello, Giovanni Luca; Augier, Romain; Laurent, Valentin; Roche, Vincent; Jolivet, Laurent


    Strain localization is a fundamental process determining plate tectonics. It is expressed in the ductile field by shear zones where strain concentrates. Despite their worldwide distribution in most metamorphic units, their detailed characterization and processes comprehension are far to be fully addressed. In this work, a graphic approach to tectono-metamorphic facies identification is applied to the Delfini Shear Zone in Syros (Cyclades, Greece), which is mostly characterized by metabasites displaying different degree of retrogression from fresh eclogite to prasinite. Several exhumation mechanisms brought them from the depths of the subduction zone to the surface, from syn-orogenic exhumation to post-orogenic backarc extension. Boudinage, grain-size reduction and metamorphic reactions determinate strain localization across well-deformed volumes of rocks organized in a hierarchic frame of smaller individual shear zones (10-25 meters thick). The most representative of them can be subdivided in 5 tectono-metamorphic (Tm) facies, TmA to E. TmA records HP witnesses and older folding stages preserved within large boudins as large as 1-2 m across. TmB is characterized by much smaller and progressively more asymmetric boudins and sigmoids. TmC is defined by well-transposed sub- to plane-parallel blueschist textures crossed by chlorite-shear bands bounding the newly formed boudins. When strain increases (facies TmD-E), the texture is progressively retrograded to LP-HT greenschist-facies conditions. Those observations allowed us to establish a sequence of stages of strain localization. The first stage (1) is determined by quite symmetric folding and boudinage. In a second stage (2), grain-size reduction is associated with dense shear bands formation along previously formed glaucophane and quartz-rich veins. With progressively more localized strain, mode-I veins may arrange as tension gashes that gradually evolve to blueschist shear bands. This process determinates the

  9. Exploring the Variability of Late Cenozoic Exhumation Rates across the Himalayan Rain Shadow (United States)

    Schultz, M.; Hodges, K. V.; Ehlers, T. A.; Van Soest, M. C.; Wartho, J. A.; McDonald, C.


    The Himalayan ranges of South Asia form one of the world's most impressive rain shadows. Data from the NASA - Japan Aerospace Exploration Agency Tropical Rainfall Measurement Mission (TRMM) suggest that precipitation in the central Himalaya drops from more than four meters per year along the southern flanks of the Higher Himalaya (falling mostly as rain during the summer monsoon) to about half a meter per year north of the range crest on the southern Tibetan Plateau. While a correlation between modern precipitation and erosion seems intuitive, important questions remain regarding how far backward in time the correlation might extend. Previous investigations of the relationships between precipitation patterns and thermochronologic cooling dates south of the Himalayan range crest have yielded discrepant results, partly due to the fact that many were conducted along deep trans-Himalayan gorges that serve to channel monsoon storms locally northward, sometimes obscuring broader trends. We are addressing this problem through the comparative studies of bedrock exhumation on million-year timescales north and south of the range crest in transects that are not along major trans-Himalayan gorges. Our low-temperature thermochronology dataset from Greater Himalayan Sequence leucogranites and sillimanite gneisses north of the range crest indicate cooling through the white mica 40Ar/39Ar closure isotherm between 15.5 - 14.5 Ma with zircon (U-Th)/He ages ranging from 14.5 - 11 Ma. Though (U-Th)/He systematics of apatites from these samples is complex, our data point to 9 - 8 Ma cooling through the ~70°C isotherm. Our developing dataset from the Khumbu Himal region south of the range crest thus far indicates cooling through ApHe closure occurred more recently at 3 - 2 Ma, about 5 - 6 million years later those from southern Tibet. We will be investigating this dataset further using the 1-D thermal model QTQt as well as the 1-D thermal-kinematic model Pecube.

  10. Exhumation and reburials of some anticommunist partisans in county of Cluj, Romania, 2009-2010

    Directory of Open Access Journals (Sweden)

    Gherasim Florin


    Full Text Available After the Second World War, Romania entered under the USSR political and military sphere of influence, which led to the installation of the communist government. In years that followed many Romanian citizens who didn’t agree with the new regime or its ideology were subjected to terror and repression. Any person suspected of being an enemy of the people would end up in political jails or put to death through collective executions. But there were also people who stood up against the regime. Groups of partisans emerged, groups that endured in forests and mountains for many years, standing up to the Securitatea, the repressive instrument of the state. After the fall of the communist regime, the former “enemies of the people”, victims of repression, benefited from reconsideration and rehabilitation that transformed them into anticommunist heroes. A series of commemorative actions that initiated a new post-communist tradition constitute part of a process called the politics of memory. The processes of unearthing and identification of the victims’ served to map out the magnitude of the crimes, and inventory evidence against the perpetrators. The factual data gathered will be used as incriminating evidence which will help with convicting the executioners. At the same time, the commemorative actions of a large number of victims may, through the representative voices of the survivors’ descendants, symbolically reopen the wounds, cultivate trauma, demonize the Other, identify the Scapegoat. My research aims to show how these theories and mechanisms remain valid and apply to the case of people who were victims of communist repression through isolated and almost anonymous executions. The murder was committed in silence and the murdered is condemned to being forgotten. The exhumation and reburial also remain events with local reverberations.

  11. Magnitude and spatial patterns of erosional exhumation in the Nevadaplano, eastern Nevada and western Utah: insights from a Paleogene paleogeologic map (United States)

    Long, S. P.


    The hinterland of the Sevier orogenic belt in Nevada and westernmost Utah has been interpreted as an ancient, high-elevation orogenic plateau, or 'Nevadaplano' that extensionally collapsed during Tertiary time. The cumulative effects of this extension have obscured evidence for a relict, low-relief region. To illustrate both the pre-extensional structural geometry and structural relief, a paleogeologic (or 'subcrop') map showing the distribution of Neoproterozoic, Paleozoic, and Triassic rocks exposed beneath a regional Eocene to Oligocene unconformity has been compiled for the Nevadaplano region. The map area extends from the trace of the westernmost major Sevier thrust system in western Utah to the Roberts Mountains thrust in central Nevada. Using published thicknesses of sedimentary rocks deposited in Nevada and Utah between the Neoproterozoic and the Triassic, the paleogeologic map becomes a map of exhumation, which contours the magnitude of sedimentary rock removed prior to the Paleocene. The exhumation map highlights a ~150 km wide region of low structural relief and minimal (Bolivia. Regional domains defined on the subcrop map include: 1) Cambrian subcrop levels in the hanging wall of the DeLamar-Wah-Wah-Canyon Range (DWC) thrust system and Sevier culmination, which young westward to Mississippian and higher levels; 2) a broad region of eastern Nevada and westernmost Utah that is devoid of regional-scale, surface-breaching thrust faults, and has subcrop levels between Mississippian and Triassic, indicating relatively low structural relief; and 3) subcrop levels varying between Neoproterozoic and Permian in the Central Nevada thrust belt (CNTB), indicating significant structural relief. Isolated segments of CNTB structures can be correlated by their subcrop patterns, and can be traced southward to connect with thrust faults in southern Nevada. The exhumation map can be divided into three zones that exhibit significant across-strike magnitude changes: 1) high

  12. Spatial variation in exhumation rates across Ladakh and the Karakoram: New apatite fission track data from the Eastern Karakoram, NW India (United States)

    Wallis, David; Carter, Andrew; Phillips, Richard J.; Parsons, Andrew J.; Searle, Michael P.


    Characterization of low-temperature cooling histories and associated exhumation rates is critical for deciphering the recent evolution of orogenic regions. However, these may vary significantly over relatively short distances within orogens. It is pertinent therefore to constrain cooling histories and hence exhumation rates across major tectonic boundaries. We report the first apatite fission track ages from the Karakoram Fault Zone in the Eastern Karakoram range, which forms part of the western margin of the Tibetan Plateau. Ten samples, from elevations of 3477-4875 m, have apatite fission track dates from 3.3 ± 0.3 Ma to 7.4 ± 1.1 Ma. The ages correspond to modeled average erosional exhumation rates of 0.67 + 0.27/-0.18 mm/yr across the Eastern Karakoram. The results are consistent with a trend northward from the Indus suture zone, across the Ladakh terrane and into the Karakoram, in which tectonic uplift associated with crustal thickening increases toward the north, raising elevation and promoting glaciation and generation of extreme relief. As a result, erosion and exhumation rates increase south to north. Present-day precipitation on the other hand varies little within the study area and on a larger scale decreases southwest to northeast across this portion of the orogen. The Eastern Karakoram results highlight the diverse patterns of exhumation driven by regional variations in tectonic response to collision along the western margin of Tibet.

  13. Growth of metamorphic and peritectic garnets in ultrahigh-pressure metagranite during continental subduction and exhumation in the Dabie orogen (United States)

    Xia, Qiong-Xia; Wang, Hao-Zheng; Zhou, Li-Gang; Gao, Xiao-Ying; Zheng, Yong-Fei; Van Orman, James Ashton; Xu, Haijun; Hu, Zhaochu


    Two generations of garnet are recognized in ultrahigh-pressure (UHP) metagranite from the Dabie orogen by a combined study of petrography, major and trace element profiles in garnet, and phase equilibrium modeling for metagranite. The results enable distinction between metamorphic and peritectic garnet on the basis of BSE images, and major and trace element compositions. Our research provides new insights into the growth of anatectic garnet due to dehydration melting of UHP metamorphic rocks during exhumation from mantle depths. The first generation of garnet (Grt-I) occurs as a broad domain in the center, which is related to metamorphic growth during prograde subduction. This garnet is dark in BSE images, rich in grossular and poor in almandine and pyrope. The chondrite-normalized rare earth element (REE) patterns show LREE depletion and flat MREE-HREE patterns. The second generation of garnet (Grt-II) occurs as a rim of euhedral garnet, or as patches in Grt-I domains, recrystallized after dissolution of preexisting metamorphic garnet in the presence of anatectic melts during exhumation. It is bright in BSE images, poor in grossular, and rich in almandine and pyrope contents. Trace element analyses on Grt-II domains yield high contents of Sc, Cr, Y and HREE and low contents of Ti and MREE. The chondrite-normalized REE patterns exhibit LREE depletion, and steep MREE-HREE patterns. Based on REE partitioning between garnet and zircon/titanite, the last growth times for metamorphic and anatectic garnets are constrained by zircon and titanite U-Pb ages to be 240 Ma and 220 Ma, respectively. Based on anatectic microstructures and a modeled P-T pseudosection, it is suggested that dehydration melting occurred at 2.0-2.5 GPa during exhumation. Melting occurred through the breakdown of phengite via the peritectic reaction: garnet (I) + phengite + plagioclase + quartz → garnet (II) + biotite + K-feldspar + melt.

  14. Thrusting between exhumed mantle blocks at the Gorringe Bank (SW Iberian margin): Evidence from combined seismic and gravity modeling (United States)

    Sallarès, V.; Martinez-Loriente, S.; Prada, M.; Gailler, A.; Gutscher, M.-A.; Bartolome, R.; Gracia, E.


    The Gorringe Bank is a massive seamount located offshore the SW Iberian margin that displays one of the largest gravity anomalies on Earth's oceans. To determine its deep seismic structure, a wide-angle seismic transect with OBS/H crossing it from the Tagus to Horseshoe Abyssal plains, was acquired in 2008. The corresponding velocity model, obtained by joint refraction and reflection travel-time inversion, displays a variably-thick sedimentary layer on top of a basement showing a strong vertical velocity gradient and no evidence for a crust-mantle boundary, not only in the Gorringe Bank but also in the adjacent segments of the deep oceanic basins. The seismic structure closely resembles that of exhumed mantle sections described along the Western Iberian margin and largely differs from that of either oceanic or extended continental crust. A velocity-derived density model assuming that the basement is made of serpentinized peridotite matches well the observed gravity anomaly, showing a basement with a variable degree of serpentinization, decreasing from ~90 % at the seafloor to ~20 % at 10 km deep. Our preferred interpretation is that the Gorringe Bank was initially the central segment of an exhumed mantle band that included also the present-day Eastern Tagus and Western Horseshoe basins. This band, which constitutes the southernmost and oldest section of the Western Iberia oceanic domain, was probably exhumed in the Earliest Cretaceous, during the onset of the North Atlantic opening. During the WNW-ESE Neogene compression, the westernmost Horseshoe basin was thrust on top of the easternmost Tagus basin, uplifting the Gorringe Bank.

  15. Evolution of the Xiaotian-Mozitan fault and its implications for exhumation of Dabie HP-UHP rocks

    Institute of Scientific and Technical Information of China (English)

    Biwei Xiang; Yongsheng Wang; Changcheng Li; Guang Zhu; Yonghong Shi


    The Xiaotian-Mozitan fault (XMF) located north of the Dabie orogenic belt separates the North Dabie complex to the south from the Beihuaiyang low-grade metamorphic rocks to the north. It comprises several NW-striking ductile shear zones and brittle faults. The brittie faults obviously overprinted on the ductile shear zones and promoted the development of the volcanic basins in early Cretaceous to the north, which suggests that the brittle faults were normal faults formed in early Cretaceous during doming of the Dabie orogenic belt. The ductile shear zone superposed on the north Dabie gray gneiss. and it is an important channel where the Dabie HP-UHP rocks exhumed. For obtaining new structural constraint on exhumation of the HP-UHP rocks, we present here experimental results on the microstructure, quartz C-axis fabrics and the microprobe analyses of phengite. The ductile shear zone was determined to be formed at a temperature of 600-650℃ and pressure of 1.1GPa by the mineral deformation, microprobe analyses and geobarometry of Siin-phengite of the mylonite, the results suggest that the mylonite now exposed on the surface experienced an upper amphibolite-facies metamorphism in the lower crust. The mineral stretching lineation varies from horizontal in the east segment to sub-dip in the west. Shear sense indicators from outcrop and thin sections of orientated specimen and quartz C-axis fabrics suggest that the XMF is a sinistral normal fault. The kinematics analysis of the ductile shear zone indicates that the exhumation of Dabie HP-UHP rocks is the results of a SE-directed extrusion and an anticlockwise rotation around its eastern pivot simultaneously.

  16. Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision (United States)

    Song, Shuguang; Niu, Yaoling; Su, Li; Wei, Chunjing; Zhang, Lifei


    Modern adakite or adakitic rocks are thought to result from partial melting of younger and thus warmer subducting ocean crust in subduction zones, with the melt interacting with or without mantle wedge peridotite during ascent, or from melting of thickened mafic lower crust. Here we show that adakitic (tonalitic-trondhjemitic) melts can also be produced by eclogite decompression during exhumation of subducted and metamorphosed oceanic/continental crust in response to continental collision, as exemplified by the adakitic rocks genetically associated with the early Paleozoic North Qaidam ultra-high pressure metamorphic (UHPM) belt on the northern margin of the Greater Tibetan Plateau. We present field evidence for partial melting of eclogite and its products, including adakitic melt, volumetrically significant plutons evolved from the melt, cumulate rocks precipitated from the melt, and associated granulitic residues. This “adakitic assemblage” records a clear progression from eclogite decompression and heating to partial melting, to melt fractionation and ascent/percolation in response to exhumation of the UHPM package. The garnetite and garnet-rich layers in the adakitic assemblage are of cumulate origin from the adakitic melt at high pressure, and accommodate much of the Nb-Ta-Ti. Zircon SHRIMP U-Pb dating shows that partial melting of the eclogite took place at ∼435-410 Ma, which postdates the seafloor subduction (>440 Ma) and temporally overlaps the UHPM (∼440-425 Ma). While the geological context and the timing of adakite melt formation we observe differ from the prevailing models, our observations and documentations demonstrate that eclogite melting during UHPM exhumation may be important in contributing to crustal growth.

  17. Late Paleozoic deformation and exhumation in the Sierras Pampeanas (Argentina): 40Ar/39Ar-feldspar dating constraints (United States)

    Löbens, Stefan; Oriolo, Sebastián; Benowitz, Jeff; Wemmer, Klaus; Layer, Paul; Siegesmund, Siegfried


    Systematic 40Ar/39Ar feldspar data obtained from the Sierras Pampeanas are presented, filling the gap between available high- (>~300 °C) and low-temperature (Pie de Palo regions, whereas the Sierras de San Luis and the Sierra de Comechingones regions record exhumation during the Carboniferous. Comparison between new and available data points to a Carboniferous tectonic event in the Sierras Pampeanas, which represents a key period to constrain the early evolution of the proto-Andean margin of Gondwana. This event was probably transtensional and played a major role during the evolution of the Paganzo Basin as well as during the emplacement of alkaline magmatism in the retroarc.

  18. Continental hyperextension, mantle exhumation, and thin oceanic crust at the continent-ocean transition, West Iberia: New insights from wide-angle seismic (United States)

    Davy, R. G.; Minshull, T. A.; Bayrakci, G.; Bull, J. M.; Klaeschen, D.; Papenberg, C.; Reston, T. J.; Sawyer, D. S.; Zelt, C. A.


    Hyperextension of continental crust at the Deep Galicia rifted margin in the North Atlantic has been accommodated by the rotation of continental fault blocks, which are underlain by the S reflector, an interpreted detachment fault, along which exhumed and serpentinized mantle peridotite is observed. West of these features, the enigmatic Peridotite Ridge has been inferred to delimit the western extent of the continent-ocean transition. An outstanding question at this margin is where oceanic crust begins, with little existing data to constrain this boundary and a lack of clear seafloor spreading magnetic anomalies. Here we present results from a 160 km long wide-angle seismic profile (Western Extension 1). Travel time tomography models of the crustal compressional velocity structure reveal highly thinned and rotated crustal blocks separated from the underlying mantle by the S reflector. The S reflector correlates with the 6.0-7.0 km s-1 velocity contours, corresponding to peridotite serpentinization of 60-30%, respectively. West of the Peridotite Ridge, shallow and sparse Moho reflections indicate the earliest formation of an anomalously thin oceanic crustal layer, which increases in thickness from ~0.5 km at ~20 km west of the Peridotite Ridge to ~1.5 km, 35 km further west. P wave velocities increase smoothly and rapidly below top basement, to a depth of 2.8-3.5 km, with an average velocity gradient of 1.0 s-1. Below this, velocities slowly increase toward typical mantle velocities. Such a downward increase into mantle velocities is interpreted as decreasing serpentinization of mantle rock with depth.

  19. The Cora Lake Shear Zone, an Exhumed Deep Crustal Lithotectonic Discontinuity, Western Churchill Province, Canada (United States)

    Regan, S.; Leslie, S.; Holland, M. E.; Williams, M. L.; Mahan, K. H.; Jercinovic, M. J.


    Deep crustal flow is a fundamental tectonic process that may serve to reduce topographic gradients, especially in overthickened collisional orogens. Recent studies have utilized numerical models and seismic interpretations, but generally in two dimensions. Although useful, two dimensional models can not fully characterize lower crustal flow or coupling of crustal layers because they cannot fully incorporate lateral heterogeneity in the flow field. The Athabasca Granulite terrane, in northern Saskatchewan, is an exposed deep crustal terrane that underwent granulite grade deformation during the Neoarchean (ca. 2.55), then cooled isobarically for 600 m.y., and then was reactivated during the Paleoproterozoic (ca. 1.9 Ga). Regional exhumation occurred at roughly 1.85 Ga. This exposure, is a field laboratory for studying lower crustal flow, stabilization, and reactivation. Recent work suggests that the northwestern domain, dominated by the multiphase, opx-bearing, Mary batholith, underwent top-to-the-east lower crustal flow during the Neoarchean. The Chipman domain, to the SE , is primarily underlain by the 3.2 Ga, Chipman tonalite straight gneiss, which was likely restitic, and rheologically strong during the 2.6 Ga flow event. The Cora Lake shear zone (CLsz), which divides the two domains, is interpreted to represent a lithotectonic, compositional, and rheologic boundary within the deep crust. Recent mapping of the western gradient of the CLsz has provided insight into the role and evolution of the rheologic discontinuity and its relationship to crustal flow. The Mary granite (gneiss) contains excellent assemblages for P-T and pseudosection analysis. Interlayered felsic granulite contain abundant monazite for in-situ geochronology. An intense subhorizontal tectonic fabric (S1), interpreted to be the product of crustal flow, is present in both units. This early fabric was locally crenulated, folded, and transposed, by a sub-vertical S2 fabric. Current work involves

  20. Late Triassic syn-exhumation magmatism in central Qiangtang, Tibet: Evidence from the Sangehu adakitic rocks (United States)

    Liu, Han; Wang, Bao-di; Ma, Long; Gao, Rui; Chen, Li; Li, Xiao-bo; Wang, Li-quan


    The geodynamic setting of Late Triassic magmatic activity along the Longmu Co-Shuanghu suture zone (LSSZ) in central Qiangtang, Tibet is a matter of debate. This paper presents zircon LA-ICP-MS U-Pb ages, zircon Hf isotopic compositions, and whole-rock geochemical data for the Sangehu (SGH) granitic intrusion in central Qiangtang, and addresses the petrogenesis of Late Triassic magmatism, and the history of collision between the northern and southern Qiangtang terranes. The SGH pluton consists mainly of biotite adamellite with mafic microgranular enclaves (MMEs), and small amounts of K-feldspar granite. The biotite adamellite, MMEs, and K-feldspar granite give ages of 207.8 ± 3.0 Ma, 212.4 ± 31 Ma, and 211.6 ± 3.8 Ma, respectively. The MMEs show magmatic textures and acicular apatite, and are coeval with the host biotite adamellite, suggesting they were produced by magma mixing. All samples from the SGH pluton show high Sr and low Y contents, and positive Eu anomalies, similar to adakitic rocks. The high K2O contents and low Mg#, Cr, and Ni contents, and enriched Hf isotopic characteristics of the zircons indicate that these magmas were derived from the partial melting of thickened crust. However, the whole-rock geochemical data and zircon Hf isotopic compositions also reveal heterogeneity at the source. The combined magmatic and metamorphic records suggest that Triassic magmatic activity in central Qiangtang was closely related to the collision of the northern and southern Qiangtang terranes. The large-scale Late Triassic (225-200 Ma) magmatic event in central Qiangtang may have resulted from the breakoff of the Longmu Co-Shuanghu Tethys Ocean lithospheric slab in the early Late Triassic (236-230 Ma). The Late Triassic magmatic rocks, including adakitic rocks, are coeval with retrograde high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks in central Qiangtang, and show characteristics of syn-exhumation magmatism. The early adakitic rocks (>220 Ma

  1. H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones (United States)

    Labrousse, L.; Duretz, T.; Gerya, T.


    We present two-dimensional numerical models of plate subduction and collision inspired by the Scandinavian Caledonian orogeny to investigate the possible impact of continental crust partial melting on the exhumation of ultra-high pressure metamorphic rocks. Three possible reactions were tested: low temperature solidus representing H2O-fluid-saturated partial melting, and two end-member reaction curves for dehydration melting. Thermo-mechanical effects of partial melting were implemented as (1) a viscosity decrease as a determined rheologically critical melt percentage was reached (here 0.1), (2) a change in effective heat capacity and adiabatic heating/cooling accounting for a latent heat term in the heat equation. Among the 3 tested reactions, only H2O-fluid-saturated partial melting drastically modifies the collision dynamics from the non-melting reference model holding all other parameters constant. A substantially low general viscosity truncation (here 1017 Pa s) is needed to properly resolve the effect of partial melting on deep collision processes. Low temperature melting indeed induces the development of a low viscosity buoyant plume prior to slab detachment, where migmatites exhume from UHP conditions at rates and with pressure-temperature paths similar to the natural values acknowledged for the Norwegian Caledonides. High temperature melting has no drastic influence on early collision dynamics. While positive buoyancy remains the first order driver for the exhumation of buried continental rocks, exhumation initiates in these cases with eduction subsequent to slab detachment. Melting and formation of a migmatite plume can later occur along decompression path while continental crust undergoes thermal reequilibration at temperatures above 900 °C. Some of the partially molten material can also relaminate in the overriding plate rather than exhume within the collision zone. Even if minor in terms of amount of magma produced, H2O-fluid-saturated partial melting

  2. Insights on high-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW Iberia (United States)

    José Fernández, Francisco; Llana-Fúnez, Sergio; Valverde-Vaquero, Pablo; Marcos, Alberto; Castiñeiras, Pedro


    High-grade, highly deformed gneisses crop out continuously along the Masanteo peninsula and constitute the upper part of the lower crustal section in the Cabo Ortegal nappe (NW Spain). The rock sequence formed by migmatitic quartzo-feldspathic (qz-fsp) gneisses and mafic rocks records the early Ordovician (ca. 480-488 Ma) injection of felsic dioritic/granodioritic dykes at the base of the qz-fsp gneisses, and Devonian eclogitization (ca. 390.4 ± 1.2 Ma), prior to its exhumation. A SE-vergent ductile thrust constitutes the base of quartzo-feldspathic gneissic unit, incorporating mafic eclogite blocks within migmatitic gneisses. A NW-vergent detachment displaced metasedimentary qz-fsp gneisses over the migmatites. A difference in metamorphic pressure of ca. 0.5 GPa is estimated between both gneissic units. The tectono-metamorphic relationships of the basal ductile thrust and the normal detachment bounding the top of the migmatites indicate that both discrete mechanical contacts were active before the recumbent folding affecting the sequence of gneisses during their final emplacement. The progressive tectonic exhumation from eclogite to greenschist facies conditions occurred over ca. 10 Ma and involved bulk thinning of the high-grade rock sequence in the high pressure and high temperature (HP-HT) Cabo Ortegal nappe. The necessary strain was accommodated by the development of a widespread main foliation, dominated by flattening, that subsequently localized to a network of anastomosing shear bands that evolved to planar shear zones. Qz-fsp gneisses and neighbouring mafic granulites were exhumed at > 3 mm yr-1, and the exhumation path involved a cooling of ˜ 20 °C/100 MPa, These figures are comparable to currently active subduction zones, although exhumation P-T trajectory and ascent rates are at the hotter and slower end in comparison with currently active similar settings, suggesting an extremely ductile deformation environment during the exhumation of qz

  3. Geophysical fingerprints of hyper-extended, exhumed and embryonic oceanic domains: the example from the Iberia-Newfoundland rifted margins (United States)

    Stanton, Natasha; Manatschal, Gianreto; Autin, Julia; Sauter, Daniel; Maia, Marcia; Viana, Adriano


    This study investigates the magnetic and gravity signatures and associated seismic character of hyper-extended, exhumed and embryonic oceanic domains along the conjugate Iberia-Newfoundland rifted margins. As these margins have been drilled down to basement along their distal parts, it is possible to explore and test different geophysical techniques and interpretations. The aims of this work are twofold: (1) to investigate the location and nature of the two main marginal boundaries—the necking zone and the J Anomaly, which define the limits of major domains; and (2) to map the lateral variations of gravity and magnetic signatures and their detailed correlation with seismic data, from the proximal margin until the first unequivocal oceanic magnetic anomaly (e.g. C34 Anomaly). The results point out that the J Anomaly corresponds to a first-order tectono-magmatic boundary, with a basement formed by polyphase magmatism. It marks the boundary between the exhumed mantle domain, with little magmatic additions, from a domain oceanwards that reveals comparable trends, frequencies and a general magnetic pattern at both sides of the Atlantic, suggesting a coeval evolution. We propose that the domain between the J and the C34 Anomalies was formed by an embryonic spreading system, with intermittent budgets of magma, similar to those observed at very slow spreading systems. The J Anomaly may thus correspond to the location of lithospheric breakup though its origin and the nature of the domain oceanwards remains to be constrained.

  4. Using Detrital Zircon, Rutile and White Mica Chronometry to Constrain Exhumation and Provenance of the Brahmaputra River in the Eastern Himalaya (United States)

    Bracciali, L.; Parrish, R. R.; Najman, Y.; Carter, A.; Condon, D. J.; Horstwood, M. S.; Wijbrans, J. R.


    . These two techniques, with a closure temperature of 350-420°C for Ar diffusion in white mica and of ~240°C for the zircon fission track system, are especially suitable to date cooling from after the last stage of low-grade metamorphism to the recent exhumation and/or uplift history of the source terrain. This powerful multi-chronometer has been applied to detrital samples from modern rivers draining the eastern Himalayan orogen, and examples will be presented, with particular emphasis on the Yarlung Tsangpo-Brahmaputra river drainage where the lower temperature thermochronometers reveal the Plio-Pleistocene very rapid exhumation of the Namche Barwa syntaxis. [1] Bracciali L., Parrish R.R., Condon D., Horstwood M.S.A., Najman,Y., Two new rutile reference materials for in situ U-Pb LA-MC-ICP-MS dating and applications to sedimentary provenance, submitted to Chemical Geology.

  5. Putting weathering into a landscape context: Variations in exhumation rates across the Colorado Front Range (United States)

    Anderson, Suzanne P.; Foster, Melissa A.; Anderson, Scott W.; Dühnforth, Miriam; Anderson, Robert S.


    canyon-edge basins evidence that topographic slope affects weathering rates? We argue that it is more likely that these high erosion rates reflect faster weathering in areas with thinner soil cover. A recent major storm unleashed landslides and debris flows from ~10% of these canyon-edge basins. On average, the volume of material evacuated in these basins was equivalent to ~300 years of soil production by weathering at these rates, approximately the recurrence interval of the storm. The conceptual model that emerges is that agents that cut into rock (bedrock rivers, glaciers) set the pace for exhumation. Adjoining hillslopes erode at a pace set by weathering in the prevailing climate/vegetation regime, conditioned by the ability of sediment transport processes to limit soil thickness on the slopes.

  6. The Freyenstein Shear Zone - Implications for exhumation of the South Bohemian Batholith (Moldanubian Superunit, Strudengau, Austria) (United States)

    Griesmeier, Gerit; Iglseder, Christoph; Konstantin, Petrakakis


    infiltration under lower greenschist-facies conditions locally lead to sericitization of feldspar and development of pseudomorphs after it. In addition, syn-mylonitic biotite has been chloritized mimetically. Chlorite growth across the mylonitic foliation occurs rarely. Brittle faulting, overprinting the shear zone features, is documented by the occurrence of numerous harnish planes. They show normal faulting to the N with angles around 30° and locally sinistral shear-sense. The Freyenstein shear zone belongs to a system of NE-SW striking shear zones and faults in the Moldanubian superunit and is located at the border between the SBB and MN ductily deforming both. Therefore, it plays an important role in exhumation processes of last stage SBB (synkinematic) intrusions during Late Variscan orogenic extension. According to cooling ages in other shear zones and (synkinematic) intrusions an age of ca. 320-290 Ma for the ductile deformation can be assumed.

  7. Short-lived subduction and exhumation in Western Papua (Wandamen peninsula): Co-existence of HP and HT metamorphic rocks in a young geodynamic setting (United States)

    François, Camille; de Sigoyer, Julia; Pubellier, Manuel; Bailly, Vivien; Cocherie, Alain; Ringenbach, Jean-Claude


    origin, confirmed by inclusions of kyanite. The metamorphic zircons are dated between 5.61 ± 0.04 Ma and 8.1 ± 1.1 Ma. These very young metamorphic ages attest for a rapid subduction and exhumation event.

  8. Using Detrital Geochronologic and Thermochronologic "Double-Dating" to Constrain Depositional Age, Provenance, and Exhumation Signals in Ancient Forearc Basins (United States)

    Orme, D. A.


    The application of coupled detrital zircon U-Pb geochronology and (U-Th)/He thermochronology to sedimentary basins has the potential for unprecedented details about grain provenance, depositional age and source and basin exhumation signals. Although several studies have implored this technique, it is underutilized and may prove useful in geologic settings that are traditionally difficult to explore. For example, constraining the depositional age of strata in ancient forearc basins is challenging as many horizons are devoid of fossils and post-burial diagenesis of limestone beds limits biostratigraphic age control. This study applies U-Pb detrital zircon geochronology to clastic rocks from the Cretaceous-Eocene Xigaze forearc basin in southern Tibet to (1) to determine the provenance of forearc basin strata and (2) to constrain a maximum depositional age of stratigraphic horizons using the youngest distinct age group from a sample. In addition, (U-Th)/He thermochronology was applied to a subset of the detrital zircons on which U-Pb ages were previously determined in order to determine the timing of exhumation of Xigaze forearc strata and its source region. The use of young populations of zircons is a good method for age control in the Xigaze forearc basin because magmatism in the source area was more-or-less continuous and the lag time between the youngest zircons in a sample and the time of that samples deposition is likely relatively small. A total of 2,330 zircon grains yielded ages with acceptable precision and concordance for geochronologic interpretation. Together with sandstone petrography, the detrital zircons indicate that the primary source of detritus in the basin from ~113 to 54 Ma was the Gangdese magmatic arc. Analysis of the youngest age component of individual samples reveals a decrease in the youngest ages upsection, consistent with maximum depositional ages that are close to the likely true depositional age based on intervening tuff layers. Double

  9. Low-temperature thermochronology of the northern Thomson Orogen: Implications for exhumation of basement rocks in NE Australia (United States)

    Verdel, Charles; Stockli, Daniel; Purdy, David


    The Tasmanides of eastern Australia record much of the Phanerozoic tectonic development of the retreating Pacific-Australia plate boundary and are an oft-cited example of an orogen that has undergone "tectonic mode switching." To begin to constrain the timing of exhumation of basement rocks that are now exposed in portions of the NE Tasmanides, we measured apatite and zircon (U-Th)/He ages from the Thomson Orogen and overlying Paleozoic strata in the back-arc of the New England Orogen in NE Australia. Zircon (U-Th)/He ages from basement samples (including those recovered from boreholes at depths of up to 1.1 km) are characterized by large inter- and intra-sample variability and range from approximately 180 Ma (Early Jurassic) to 375 Ma (Late Devonian). (U-Th)/He zircon ages from several individual samples are negatively correlated with effective uranium (eU), a pattern that is also true of the dataset as a whole, suggesting that variations in U and Th zoning and radiation damage are partially responsible for the age variability. The oldest zircon (U-Th)/He cooling ages coincide with the formation of regionally extensive Late Devonian-early Carboniferous back-arc basins, suggesting that Late Devonian extension played a significant role in exhumation of parts of the northern Thomson Orogen. Apatite (U-Th)/He ages from a basement sample and a late Permian sandstone in the overlying Bowen Basin, which are also marked by intra-sample variability and age-eU correlations, span from the Early Cretaceous through Oligocene, in general agreement with previous apatite fission track data. In conjunction with observations of key geologic relationships and prior K-Ar and 40Ar/39Ar data, our results suggest four overall phases in the thermal history of the northern Thomson Orogen: (1) Cambrian-early Silurian metamorphism during the Delamerian and Benambran Orogenies; (2) protracted cooling during the Late Devonian through mid-Permian that likely resulted from extensional

  10. Cenozoic exhumation of the internal Zagros : First constraints from low-temperature thermochronology and implications for the build-up of the Iranian plateau

    NARCIS (Netherlands)

    François, T.; Agard, P.; Bernet, M.; Meyer, B.; Chung, S.-L.; Zarrinkoub, M. H.; Burov, E.; Monié, P.


    The Iranian plateau is a flat ~. 1.5-2. km high plateau thought to result from the collision between the Arabian and Eurasian plates since ~. 30 ± 5. Ma, and may represent a young analogue to the so far better studied Tibetan plateau. In order to constrain the exhumation history of the internal Zagr

  11. Amphibole equilibria as monitors of P-T path and process in the exhumation of HP/UHP terranes (United States)

    Waters, David; Airaghi, Laura; Czertowicz, Thomas


    Recent advances in modelling and the development of refined activity-composition relations allow the calculation of phase diagrams involving complex mineral solid solutions, such as calcic, sodic-calcic and sodic amphiboles (e.g. Diener et al., 2007, J metamorphic Geol.). Amphiboles are commonly found in eclogite facies metabasites, and formed at different metamorphic stages. Such rocks commonly show complex reaction microstructures that reveal their history. The focus in this contribution is on two distinct amphibole types: coarse, post-peak matrix amphibole, and amphibole involved in symplectitic microstructures replacing omphacite. These studies serve as a test of the current activity models and calculation approaches, but more importantly as a framework for understanding the processes and P-T path during exhumation of subducted terranes. Examples are taken from the Western Gneiss Complex of Norway and from the Kaghan Valley (Pakistan), but are more generally applicable to crustal blocks that have exhumed through the P-T 'window' in which comparable petrological features develop. The microstructural types of interest here are: broad irregular interstitial amphibole grains, which commonly merge with a coarse spongy intergrowth of amphibole with quartz and/or albite (most likely replacing omphacite); and a fine-grained symplectite of low-Na clinopyroxene with sodic plagioclase and minor hornblende invading omphacite. Many specimens show these varieties as a sequence, inferred to reflect decreasing pressure (and ultimately, temperature). Amphibole compositions cover a wide range: the most sodic occur in large interstitial grains and fall near the junction of the winchite, barroisite and taramite fields of the IMA classification; they trend towards a pargasitic hornblende, still with significant glaucophane component; spongy amphiboles typically lie on a trend towards lower glaucophane component; symplectite amphibole is generally a common hornblende on a typical

  12. Long-term exhumation of a Palaeoproterozoic orogen and the role of pre-existing heterogeneous thermal crustal properties

    DEFF Research Database (Denmark)

    McGregor, E.D.; Nielsen, S.B.; Stephenson, R.A.


    Ma. Modelling the 3D exhumation of a heterogeneous crust with flat topography demonstrates that some of the variability in observed fission-track ages could be attributed to heterogeneity in crustal heat production and thermal conductivity. The remaining variability in the observed dataset...... ‘boomerang’ trend, typical of samples that have experienced contemporaneous cooling from an array of initial temperatures. One-dimensional inverse thermal modelling of single samples suggests that cooling through the partial annealing zone (c. 120–60 °C) occurred over discrete periods ranging from 100 to 300...... is attributed here to differential erosion from a variable initial topography. However, age discontinuities over short distances require other explanations such as faulting and/or unidentified compositional effects. Collectively, these results suggest that the observed data are consistent with a simple...

  13. Basement - Cover decoupling and progressive exhumation of metamorphic sediments at hot rifted margin. Insights from the Northeastern Pyrenean analog (United States)

    Clerc, Camille; Lagabrielle, Yves; Labaume, Pierre; Ringenbach, Jean-Claude; Vauchez, Alain; Nalpas, Thierry; Bousquet, Romain; Ballard, Jean-François; Lahfid, Abdeltif; Fourcade, Serge


    We compile field data collected along the eastern part of the North Pyrenean Zone (NPZ) to point to a tectonic evolution under peculiar thermal conditions applying to the basin sediments in relation with the opening of the Cretaceous Pyrenean rift. Based on this compilation, we show that when thinning of the continental crust increased, isotherms moved closer to the surface with the result that the brittle-ductile transition propagated upward and reached sediments deposited at the early stage of the basin opening. During the continental breakup, the pre-rift Mesozoic cover was efficiently decoupled from the Paleozoic basement along the Triassic evaporite level and underwent drastic ductile thinning and boudinage. We suggest that the upper Albian and upper Cretaceous flysches acted as a blanket allowing temperature increase in the mobile pre-rift cover. Finally, we show that continuous spreading of the basin floor triggered the exhumation of the metamorphic, ductily sheared pre-rift cover, thus contributing to the progressive thinning of the sedimentary pile. In a second step, we investigate the detailed geological records of such a hot regime evolution along a reference-section of the eastern NPZ. We propose a balanced restoration from the Mouthoumet basement massif (north) to the Boucheville Albian basin (south). This section shows a north to south increase in the HT Pyrenean imprint from almost no metamorphic recrystallization to more than 600 °C in the pre- and syn-rift sediments. From this reconstruction, we propose a scenario of tectonic thinning involving the exhumation of the pre-rift cover by the activation of various detachment surfaces at different levels in the sedimentary pile. In a third step, examination of the architecture of current distal passive margin domains provides confident comparison between the Pyrenean case and modern analogs. Finally, we propose a general evolutionary model for the pre-rift sequence of the Northeastern Pyrenean rifted

  14. Multiple low-temperature thermochronology constraints on exhumation of the Tatra Mountains: New implication for the complex evolution of the Western Carpathians in the Cenozoic (United States)

    Anczkiewicz, Aneta Agnieszka; Danišík, Martin; Środoń, Jan


    The tectonothermal evolution of the highest mountain range in the Carpathian arc—the Tatra Mountains— is investigated by zircon and apatite fission track and zircon (U-Th)/He (ZHe) dating methods in order to unravel the disputed exhumation and geodynamic processes in the Western Carpathians. Our data in combination with geological evidences reveal a complex Cenozoic history, with four major tectonothermal events: (i) a very low grade metamorphism of the crystalline basement at temperatures >240°C due to tectonic burial during the Eo-Alpine collision in the Late Cretaceous (~80 Ma); (ii) exhumation and cooling of the basement to temperatures 150°C after burial to 5-9 km depths by the Paleogene fore-arc basin; (iv) final exhumation of the segmented basement blocks during Oligocene-Miocene (32-11 Ma) owing to lateral extrusion of the North Pannonian plate and its collision with the European foreland. The spatial pattern of thermochronological data suggests asymmetric exhumation of the Tatra Mountains, beginning in the northwest at ~30-20 Ma with low cooling rates (~1-5°C/Ma) and propagating toward the major fault bounding the range in the south, where the youngest cooling ages (16-9 Ma) and fastest cooling rates (~10-20°C/Ma) are found. Our data prove that the Tatra Mountains shared Cenozoic evolution of other crystalline core mountains in the Western Carpathians. However, the Miocene ZHe ages suggest that the Tatra Mountains were buried to the greatest depths in the Paleogene-Early Miocene and experienced the greatest amount of Miocene exhumation.

  15. Mesozoic exhumation history and palaeolandscape of the Iberian Massif in eastern Galicia from apatite fission-track and (U+Th)/He data (United States)

    Grobe, R. W.; Alvarez-Marrón, J.; Glasmacher, U. A.; Stuart, F. M.


    Apatite fission-track (AFT) and (U+Th)/He (AHe) data, combined with time-temperature inverse modelling, reveal the cooling and exhumation history of the Iberian Massif in eastern Galicia since the Mesozoic. The continuous cooling at various rates correlates with variation of tectonic boundary conditions in the adjacent continental margins. The data provide constraints on the 107 timescale longevity of a relict paleolandscape. AFT ages range from 68 to 174 Ma with mean track lengths of 10.7 ± 2.6 to 12.6 ± 1.8 μm, and AHe ages range from 73 to 147 Ma. Fastest exhumation (≈0.25 km/Ma) occurred during the Late Jurassic to Early Cretaceous main episode of rifting in the adjacent western and northern margins. Exhumation rates have decreased since then and have been approximately one order of magnitude lower. Across inland Galicia, the AFT data are consistent with Early Cretaceous movement on post-Variscan NE trending faults. This is coeval with an extensional episode offshore. The AHe data in this region indicate less than 1.7 km of denudation in the last 100 Ma. This low exhumation suggests the attainment of a mature landscape during Late Cretaceous post-rift tectonic stability, whose remains are still preserved. The low and steady rate of denudation prevailed across inland Galicia despite minor N-S shortening in the northern margin since ≈45 Ma ago. In north Galicia, rock uplift in response to NW strike-slip faulting since Early Oligocene to Early Miocene has caused insufficient exhumation (<3 km) to remove the Mesozoic cooling signal recorded by the AFT data.

  16. Exhumation history along the eastern Amundsen Sea coast, West Antarctica, revealed by low-temperature thermochronology (United States)

    Lindow, Julia; Kamp, Peter J. J.; Mukasa, Samuel B.; Kleber, Michel; Lisker, Frank; Gohl, Karsten; Kuhn, Gerhard; Spiegel, Cornelia


    West Antarctica experienced a complex tectonic history, which is still poorly documented, in part due to extensive ice cover. Here we reconstruct the Cretaceous to present thermotectonic history of Pine Island Bay area and its adjacent coasts, based on a combination of apatite and zircon fission track and apatite (U-Th-Sm)/He thermochronology. In addition, we report petrographic information for the catchments of Pine Island, Thurston Island, and Thwaites glaciers. Our data suggest that the underlying bedrock of the Pine Island and Thwaites Glacier catchments are very different and vary from granitoids to (Cenozoic?) volcanogenic sequences and low-grade metamorphics. Our thermochronology data show that the upper crustal rocks of Pine Island Bay experienced very rapid cooling during the late Cretaceous. We attribute this rapid cooling of basement rocks and associated reduction in mean elevation to tectonic denudation driven by gravitational collapse of the Cretaceous orogen along the proto-Pacific Gondwana margin. Rapid Cretaceous crustal cooling was followed by very slow cooling during the Cenozoic, with no erosional response—within the limits of thermochronological methods—to the onset of glaciation and subsequent climatic changes. Cenozoic rifting within the West Antarctic Rift appears to have had little effect on erosion processes around Pine Island Bay; instead, our data suggest Cenozoic crustal tilting toward Pine Island Trough, a major geomorphic feature previously suggested to be a branch of the rift system.

  17. Reconstruction of methods of execution of the death penalty by shooting in the years 1949-1954 based on exhumation research of "prison fields" in Osobowicki Cemetery in Wroclaw. Part I--Historical outline and results of research conducted prior to exhumations performed in 2011. (United States)

    Szleszkowski, Łukasz


    In the period between October and December 2011, a series of exhumation research of the so-called prison quarters dating back to 1949-1954 was conducted in Osobowicki Cemetery in Wrocław. Among the buried there were political prisoners executed by shooting--genuine or alleged members of post-war independence organizations. It was a unique opportunity to determine the method of execution of the death penalty in that period because, according to historical data and the results of two test exhumations, this method considerably differed from instructions on the use of a firing squad during execution of the death penalty.

  18. Detachment within subducted continental crust and multi-slice successive exhumation of ultrahigh-pressure metamorphic rocks: Evidence from the Dabie-Sulu orogenic belt

    Institute of Scientific and Technical Information of China (English)

    LIU YiCan; LI ShuGuang


    Although tectonic models were presented for exhumation of ultrahigh-pressure (UHP) metamorphic rocks during the continental collision, there is increasing evidence for the decoupling between crustal slices at various depths within deeply subducted continental crust. This lends support to the multi-slice successive exhumation model of the UHP metamorphic rocks in the Dabie-Sulu orogen. The available evidence is summarized as follows: (1) the low-grade metamorphic slices, which have geotectonic af-finity to the South China Block and part of them records the Triassic metamorphism, occur in the northern margin of the Dabie-Sulu UHP metamorphic zone, suggesting decoupling of the upper crust from the underlying basement during the initial stages of continental subduction; (2) the Dabie and Sulu HP to UHP metamorphic zones comprise several HP to UHP slices, which have an increased trend of metamorphic grade from south to north but a decreased trend of peak metamorphic ages corre-spondingly; and (3) the Chinese Continental Science Drilling (CCSD) project at Donghai in the Sulu orogen reveals that the UHP metamorphic zone is composed of several stacked slices, which display distinctive high and low radiogenic Pb from upper to lower parts in the profile, suggesting that these UHP crustal slices were derived from the subducted upper and middle crusts, respectively. Detachment surfaces within the deeply subducted crust may occur either along an ancient fault as a channel of fluid flow, which resulted in weakening of mechanic strength of the rocks adjacent to the fault due to fluid-rock interaction, or along the low-viscosity zones which resulted from variations of geotherms and lithospheric compositions at different depths. The multi-slice successive exhumation model is different from the traditional exhumation model of the UHP metamorphic rocks in that the latter as-sumes the detachment of the entire subducted continental crust from the underlying mantle lithosphere and its

  19. Mid-Carboniferous conglomerates in southwestern Europe record early Variscan intracontinental convergence: evidence that channels were exhumed before thermal weakening of the lithosphere (United States)

    Martinez, Francisco J.; Dietsch, Craig; Aleinikoff, John; Cirès, Jordi


    The early part of the intracontinental geodynamic evolution of the Variscan chain in southwestern Europe is recorded by polymict conglomerates found in flysch basins paired with exhumed crystalline massifs. The conglomerates contain pebbles and cobbles of deformed granite and mid- to lower-crustal metamorphic rock, and in southern France and northeastern Spain have been assigned a Visean-Namurian age based on biostratigraphy. In the Catalan Coastal Ranges, where Alpine deformation and metamorphism are absent, conglomerates are deformed, cross-cut by granite, and contact metamorphosed to andalusite-cordierite grade. Foliation in the pebbles and cobbles is not coplanar with foliation in their pelitic matrix: the conglomerates record exhumation of crust that was already deformed, metamorphosed, and exhumed before the Visean. In the Guilleries massif of NE Spain, gneisses were exhumed ≈10 km before 324 Ma. Conglomerate samples from eight flysch basins, from north to south: Montagne Noire, Mouthoumet massif, SE Pyrenees, and five localities in the Catalan Coastal Ranges, were collected for detrital zircon age determinations using the USGS/Stanford SHRIMP-RG. The flysch basins have principal sources of pre-Cadomian, Cadomian, Cambro-Ordovician, Devonian, and Carboniferous ages. The dominance of Paleozoic ages indicates local orthogneiss and Variscan granite as primary sources, implying intra-Carboniferous exhumation rates as high as 5-10 mm/a. The maximum depositional age of each flysch conglomerate may show a trend of younging to the south [330 Ma (Montagne Noire) - 340 Ma (Mouthoumet) - 324 Ma (Poblet) -328 (Perinet)], suggesting deposition in front of advancing thrust nappes. In the Pineda basin, a dike of undeformed granite which cross-cuts conglomerate is 304 ± 2 Ma (SHRIMP U-Pb zircon data), providing a minimum age constraint on the time of deposition. In the Montagne Noire and the Mouthoumet massif, flysch basins are deformed by structures related to nappe

  20. Phanerozoic burial and exhumation history of southernmost Norway estimated from apatite fission-track analysis data and geological observations (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Chalmers, James A.; Rasmussen, Erik S.


    We present new apatite fission-track analysis (AFTA) data from 27 basement samples from Norway south of ~60°N. The data define three events of cooling and exhumation that overlap in time with events defined from AFTA in southern Sweden (Japsen et al. 2015). The samples cooled below palaeotemperatures of >100°C in a major episode of Triassic cooling as also reported by previous studies (Rohrman et al. 1995). Our study area is just south of the Hardangervidda where Cambrian sediments and Caledonian nappes are present. We thus infer that these palaeotemperatures reflect heating below a cover that accumulated during the Palaeozoic and Triassic. By Late Triassic, this cover had been removed from the Utsira High, off SW Norway, resulting in deep weathering of a granitic landscape (Fredin et al. 2014). Our samples were therefore at or close to the surface at this time. Palaeotemperatures reached ~80°C prior to a second phase of cooling and exhumation in the Jurassic, following a phase of Late Triassic - Jurassic burial. Upper Jurassic sandstones rest on basement near Bergen, NW of our study area (Fossen et al. 1997), and we infer that the Jurassic event led to complete removal of any remaining Phanerozoic cover in the region adjacent to the evolving rift system prior to Late Jurassic subsidence and burial. The data reveal a third phase of cooling in the early Miocene when samples that are now near sea level cooled below palaeotemperatures of ~60°C. For likely values of the palaeogeothermal gradient, such palaeotemperatures correspond to burial below rock columns that reach well above the present-day landscape where elevations rarely exceed 1 km above sea level. This implies that the present-day landscape was shaped by Neogene erosion. This is in agreement with the suggestion of Lidmar-Bergström et al. (2013) that the near-horizontal Palaeic surfaces of southern Norway are the result of Cenozoic erosion to sea level followed by uplift to their present elevations in a

  1. Basin Evolution and Exhumation of the Xigaze Forearc, Southern Tibet: Insight from Sedimentology, Stratigraphy, and Geo-Thermochronology (United States)

    Orme, D. A.; Carrapa, B.; Abbey, A. L.; Kapp, P. A.; Ding, L.


    Miscellanea-Daviesina. The along-strike variability of the Cretaceous strata suggests that, prior to collision, the diverse and irregular paleogeography of Asia's southern margin greatly influenced the three-dimensional nature and distribution of time-equivalent facies. In order to determine the timing of exhumation of Xigaze forearc strata, we utilize zircon (U-Th)/He thermochronology coupled with U-Pb geochronology. Preliminary U-Pb detrital geochronology indicates that the primary source of forearc detritus is the Gangdese magmatic arc which was active from ~150 Ma to 50 Ma. Preliminary double-dated (U-Th/He and U-Pb) zircon crystals from eight samples in ~80 Ma deposits suggest basin exhumation from 30 to 10 Ma. This time span corresponds to ages determined independently for movements occurring along the basin-bounding Great Counter Thrust system. Therefore, we postulate that this fault system was responsible for erosional exhumation of the Xigaze forearc.

  2. Mazatan metamorphic core complex (Sonora, Mexico): structures along the detachment fault and its exhumation evolution (United States)

    Granillo, Ricardo Vega; Calmus, Thierry


    The Mazatán Sierra is the southernmost metamorphic core complex (MCC) of the Tertiary extensional belt of the western Cordillera. Its structural and lithological features are similar to those found in other MCC in Sonora and Arizona. The lower plate is composed of Proterozoic igneous and metamorphic rocks intruded by Tertiary plutons, both of which are overprinted by mylonitic foliation and N70°E-trending stretching lineation. Ductile and brittle-ductile deformations were produced by Tertiary extension along a normal shear zone or detachment fault. Shear sense is consistent across the Sierra and indicates a top to the WSW motion. The lithology and fabric reflect variations in temperature and pressure conditions during extensional deformation. The upper plate consists mainly of Cambrian-Mississippian limestone and minor quartzite, covered by upper Cretaceous volcanic rocks, and then by Tertiary syntectonic sedimentary deposits with interbedded volcanic flows. Doming caused uplift and denudation of the detachment, as well as successive low-angle and high-angle normal faulting across the western slope of Mazatán Sierra. An 18±3 Ma apatite fission-track age was obtained for a sample of Proterozoic monzogranite from the lower plate. The mean fission-track length indicates rapid cooling and consequent rapid uplift of this sample during the last stage of crustal extension.

  3. Deep inside a neoproterozoic intra-oceanic arc: growth, differentiation and exhumation of the Amalaoulaou complex (Gourma, Mali) (United States)

    Berger, Julien; Caby, Renaud; Liégeois, Jean-Paul; Mercier, Jean-Claude C.; Demaiffe, Daniel


    We show here that the Amalaoulaou complex, in the Pan-African belt of West Africa (Gourma, Mali), corresponds to the lower and middle sections of a Neoproterozoic intra-oceanic arc. This complex records a 90-130-Ma-long evolution of magmatic inputs and differentiation above a subducting oceanic slab. Early c. 793 Ma-old metagabbros crystallised at lower crustal or uppermost mantle depths (25-30 km) and have geochemical characteristic of high-alumina basalts extracted from a depleted mantle source slightly enriched by slab-derived sedimentary components ((La/Sm)N high-Mg andesitic parental magma. Quartz and hornblende-gabbros (700-660 Ma) with composition typical of hydrous volcanic rocks from mature arcs ((La/Sm)N: 0.9-1.8; ɛNd: +4.6 to +5.2; 87Sr/86Sr: 0.7028-0.7031) were subsequently emplaced at mid-arc crust levels (~15 km). Trace element and isotopic data indicate that magmas tapped a depleted mantle source significantly more enriched in oceanic sedimentary components (0.2%). Exhumation occurred either in two stages (700-660 and 623 Ma) or in one stage (623 Ma) with a final exhumation of the arc root along cold P-T path (550°C, 6-9 kbar; epidote-amphibolite and greenschist facies conditions) during the main Pan-African collision event (620-580 Ma). The composition of magmas forming the Cryogenian Amalaoulaou arc and the processes leading to intra-arc differentiation are strikingly comparable to those observed in the deep section of exposed Mezosoic oceanic arcs, namely the Kohistan and Talkeetna complex. This evolution of the Amalaoulaou oceanic arc and its accretion towards the West African craton belong to the life and closure of the Pharusian Ocean that eventually led to the formation of the Greater Gondwana supercontinent, a similar story having occurred on the other side of the Sahara with the Mozambique Ocean.

  4. High-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW of Iberia

    Directory of Open Access Journals (Sweden)

    F. J. Fernández


    Full Text Available High-grade highly deformed gneisses crop out continuously along the Masanteo peninsula in the Cabo Ortegal nappe (NW Spain. The rock sequence formed by quartzo-feldspathic gneisses and mafic rocks records two partial melting events: during the Early Ordovician (ca. 480–488 Ma., at the base of the Qz-Fsp gneisses, and immediately after eclogization (ca. 390.4 ± 1.2 Ma, during its early Variscan exhumation. Despite the strain accumulated during their final exhumation in which a pervasive blastomylonitic S2 foliation was developed, primary sedimentary layering in Qz-Fsp gneisses is well preserved locally at the top of the sequence. This first stage of the exhumation process occurred in ~ 10 Ma, during which bulk flattening of the high-grade rock sequence was accommodated by anastomosing shear bands that evolved to planar shear zones. Strain was progressively localized along the boundaries of the migmatitic Qz-Fsp gneisses. A SE-vergent ductile thrust constitutes the base of gneisses, incorporating eclogite blocks-in-matrix. A NW-vergent detachment placed the metasedimentary Qz-Fsp gneisses over the migmatitic Qz-Fsp gneisses. A difference in metamorphic pressure of ca. 0.5 GPa is estimated between both gneissic units. The high-grade deformation reduced substantially the thickness of the gneissic rock sequence during the process of exhumation controlled by change in the strain direction and the progressive localization of strain. The combined movement of the top detachment and basal thrust resulted in an extrusion of the migmatites within the nappe, directed to the SE in current coordinates.

  5. Teleseismic P-wave tomography and the upper mantle structure of the Sulu orogenic belt (China): implications for Triassic collision and exhumation mechanism (United States)

    Peng, Miao; Tan, Handong; Jiang, Mei; Xu, Zhiqin; Li, Zhonghai; Xu, Lehong


    As the largest ultrahigh-pressure (UHP) metamorphic tectonic unit outcropping in the world, the Dabie-Sulu UHP metamorphic belt is considered to be one of the best areas for studying the continental dynamics. However, their continental collision and exhumation mechanism are still debated. We performed a 3D teleseismic P-wave tomography beneath the Sulu orogen for the purpose of understanding the deep structure. The tomographic results show that there is a prominently near-SN-trending low-velocity zone (LVZ) close to the Tanlu fault (TLF), indicating a slab tear of the subducted Yangtze plate (YZP) during the initial Early Triassic collision. Our results also suggest that both the Yangze crustal slab and the North China lithospheric slab were dragged downwards by the subducted oceanic slab, which constituted a ‘two-sided’ subduction mode. A conceptual geodynamic model is proposed to explain the exhumation of Sulu high- to UHP rocks and imply a polyphase exhumation driven by buoyancy of continental materials at different depth and upward extrusion of crustal partial melting rocks to the surface at the later stage.

  6. Sediments overlying exhumed continental mantle: a proxy for the morphotectonic evolution of the Ocean Continent Transition in magma-poor rifted margins (United States)

    Karpoff, A. M.; Manatschal, G.; Bernoulli, D.; Lagabrielle, Y.


    Observations from ancient and present-day magma-poor rifted margins in the Alps and Iberia provide compelling evidence that within the ocean-continent transition (OCT) crustal and sub-continental mantle rocks were exhumed along downward-concave faults which were active during final rifting and accommodated high amounts of extension. The faults are overlain by stranded allochthons of continental origin, pillow basalts, and pelagic sediments, i.e. radiolarites and/or pelagic limestones, and hemipelagic shales. Associated with the faults are tectono-sedimentary breccias and various types of clastic sediments, ranging from debris flow deposits to laminated sandstone, and quartz-rich silt- and claystones. Mineralogical studies of the shales, red jaspers, and red cherts overlying mantle rocks in the Alps of eastern Switzerland are typically quartz-rich and contain variable amounts of phyllosilicates (chlorite and/or mica), feldspars, ± calcite, oxides, pyrite, and epidote. Their main geochemical characteristic is the high silica and low iron and manganese content, which contrasts with that of "metalliferous" Fe-Mn-Si-rich sediments overlying oceanic basalts. High Fe, Ba, REE, U/Th values measured in black shales overlying mantle rocks in the proximal OCT point to a strong hydrothermal activity associated with mantle exhumation. The clastic sediments in the OCT show a wide range of compositions related to mantle, continental crust, and/or pelagic contributions. In particular, the fact that these sediments contain abundant material derived from continental basement rocks seems at odds with their occurrence on top of tectonized mantle rocks. However, drilling in the Iberia margin, where tectonized mantle rocks are overlain by sedimentary breccias (e.g. ODP Sites 1068, 1070), shed new light on the observations in the Alps. Based on drill-hole and seismic data, the tectono-sedimentary breccias drilled in the OCT off Iberia may be interpreted to result from a conveyor

  7. Linking deep earth to surface processes in the Woodlark Rift of Papua New Guinea; a framework for understanding (U)HP exhumation globally (United States)

    Baldwin, S.; Fitzgerald, P. G.; Bermudez, M. A.; Webb, L. E.; Moucha, R.; Miller, S. R.; Catalano, J. P.; Zirakparvar, N. A.


    During the Cenozoic the leading edge of the AUS plate was subducted northwards beneath the forearc of oceanic island arc(s), during its north-northeast passage over a complexly structured mantle. Sediments and basalts were metamorphosed under (U)HP conditions to form blueschists and eclogites, and lower-grade metamorphic rocks that are now exposed throughout New Guinea, primarily south of, and structurally beneath, obducted ophiolites. In the Woodlark Rift the youngest (2-8 Ma) (U)HP rocks on Earth were exhumed from mantle depths (>90 km) at plate tectonic rates (1-4 cm yr-1) west of the active Woodlark Basin seafloor spreading center rift tip. How these (U)HP rocks were exhumed is the focus of an ongoing collaborative multidisciplinary project which aims to understand linkages between deep earth, plate tectonic, and surface processes in the Woodlark Rift. Since the Late Miocene, a regionally extensive subduction complex was exhumed on the southern-rifted margin of the Woodlark Basin (Pocklington Rise), and in the lower plates of the D'Entrecasteaux, Misima, and Dayman dome metamorphic core complexes. Late Miocene-to-Pliocene metamorphism of sediments and basalts preceded diachronous exhumation from east to west, in the same direction as rift propagation. In contrast the northern-rifted margin (Woodlark Rise) comprises mid-Miocene to Pliocene volcanic flows and pyroclastic material ranging in composition from basalt to rhyolite, with capping limestone. The age of volcanic rocks on the northern-rifted margin also youngs from east to west. Pliocene to active syn-rift volcanism on the Woodlark Rise and in the D'Entrecasteaux Islands is synchronous with (U)HP exhumation, and results from decompression melting of a relict mantle wedge. As lithospheric extension proceeds, volcanic compositions evolve from subduction zone geochemical signatures (i.e., negative HFSE anomalies) toward E-MORB. Preliminary mantle convection models investigate large-scale background mantle

  8. Ongoing compression triggered exhumation of the orogenic crust in the Variscan Maures-Tanneron Massif, France - Geological arguments and thermo-mechanical tests (United States)

    Gerbault, Muriel; Schneider, Julie; Reverso-Peila, Alexandre; Corsini, Michel


    The Maures-Tanneron Massif (MTM), together with Corsica and Sardinia, hosted the South-Eastern Variscan belt and record a continuous evolution from continental collision to exhumation. We present a synthesis of the available geological and geochronogical data that explores the transition from convergence to perpendicular Permean extension in the MTM (at ~ 325 Ma ± 25 My). The migmatitic Internal Zone that composes the Western MTM displays structural clues such as backthrusting and magmatic foliations, and metamorphic data indicating exhumation of deep seated partially molten rocks at an apparent heating rate of 1-2 °C/km/My from ca. 345 Ma to 320 Ma. This suggests vertical advective heat transport during continued N140° convergence (D2 phase). In contrast at the same time, the low grade External zone composing the Eastern part of the MTM recorded exhumation of more conductive patterns at an apparent rate of 0.3-0.6 °C/km/My. It is only from ca. 320 Ma that transcurrent motion dominates in the Internal zone and progressively leaves way to N-S strecthing (D3 phase), indicative of orogenic collapse and extension and in asociation with emplacement of larger volumes of magmatism in the crust. Thermo-mechanical modeling complements this synthesis in order to highlight the conditions under which deep seated HP units could melt and massively start to exhume during maintained convergence (phase D2). Accounting for temperature dependent elasto-visco-plastic rheologies, our models explore the dynamics of an orogenic prism starting from a dis-equilibrated state just after slab break-off or delamination, at ca. 350 Ma. We simulate the development of gravitational instabilities in partially melting crust, a process that is already well known to depend on strain-rate, heat sources and strength layering. In order to reproduce the exhumation patterns of rocks from ~50 km depth over the appropriate time-scale (>20 My) and spatial extent (>100 km), a best fit was obtained with a

  9. New Constraints on the Timing and Magnitude of Deformation and Basin Exhumation in the Eastern Cordillera of NW Argentina. (United States)

    Trimble, J. D.; Carrapa, B.; Stockli, D. F.; Stutz, J.


    could be potentially related to the reactivation of Cretaceous relay-zone structures. Flexural-slip folding is the dominant mechanism of folding within the basin, with centimeter to meter scale fracture-rich and slickenside-rich beds of fine silts acting as primary slip-surfaces between thicker, more competent beds of coarse sand and conglomerate. A newly discovered intra-formational angular unconformity near the base of the Angastaco Fm. documents growth during the early stages of deposition. However, there is no clear evidence of continuous growth up section, implying at least two pulses of significant deformation during syn- and post- Miocene time. New apatite (U-Th)/He thermochronology (AHe) from six samples from the Eocene-Oligocene(?) Quebrada de los Colorados Fm and the Miocene Angastaco Fm (~18 Ma) in the Angastaco and surrounding Pucara and Tin Tin basins yields youngest ages between ca. 13.2 Ma (to the west) and ca. 10.3 Ma (to the east), and correlate with low Uranium content. We interpret these ages as representative of cooling following basin exhumation in the Miocene. The younging of those ages towards the east, together with structural data indicating young Mio-Pliocene deformation, suggests that those ages may be the result of eastward propagation of deformation into the foreland driving basin exhumation.

  10. The "granite pump": LP/HT metamorphism and exhumation in the Montagne Nore (S-France) (United States)

    Franke, W.; Doublier, M. P.; Doerr, W.; Stein, E.


    The Montagne Noire at the southern margin of the French Massif Central represents an exceptional case of a hot metamorphic core complex evolved from a thrust stack in a foreland position. The core of the structure (Zone Axiale) exposes granites and LP/HT gneisses up to anatectic grade. The hot core is encased by ENE-trending shear zones, which define a dextral pull-apart structure. Ductile extension is documented by top WSW shearing in the W, and ENE shearing in the E part of the Zone Axiale (eg, MATTE et al., 1998). Extension in ENE and reduction of the metamorphic profile are accompanied by NNW-directed contraction ("pinched pull-apart"). Palaeozoic sediments on the southern flank of the Zone Axiale exhibit only greenschist to diagenetic grades of metamorphism. Conodont alteration index (WIEDERER et al., 2002) and illite crystallinity (Doublier, this meeting) reveal a decrease of metamorphic temperature away from the hot core. Metamorphic isograds cut across the axial planes of D1 nappes. These features suggest that metamorphism was imposed by the rising hot core. Accordingly, the palaeozoic sediments show a tectonic evolution which closely resembles that of the gneissic core (extension top ENE, contraction in NNW). Structures relating to stacking (D1) have survived at the southern margin of the Montagne Noire. U-Pb studies (TIMS on single zircon and monazite) reveal peak metamorphism and magmatism already at c. 315 Ma (KLAMA et al., 2001), i.e., only <10 Ma after the end of flysch deposition in latest Visean/Early Namurian time (<= 323 Ma). The coincidence, within error, of the U-Pb ages and earlier Ar/Ar ages (MALUSKI et al., 1991) suggest rapid cooling. Synchronous granite emplacement and metamorphism is best explained by advective heating. Since granites are not generated in foreland settings, we propose derivation of the melts from areas of thickened crust adjacent to the N. Transport and emplacement of granites was essentially driven by the hydraulic

  11. Characterization and simulation of an exhumed fractured petroleum reservoir. Final report, March 18, 1996--September 30, 1998

    Energy Technology Data Exchange (ETDEWEB)

    Forster, C.B.; Nielson, D.L.; Deo, M.


    An exhumed fractured reservoir located near Alligator Ridge in central Nevada provides the basis for developing and testing different approaches for simulating fractured petroleum reservoirs. The fractured analog reservoir comprises a 90 m thickness of silty limestone and shaly interbeds within the Devonian Pilot Shale. A period of regional compression followed by ongoing basin and range extension has created faults and fractures that, in tern, have controlled the migration of both oil and gold ore-forming fluids. Open pit gold mines provide access for observing oil seepage, collecting the detailed fracture data needed to map variations in fracture intensity near faults, build discrete fracture network models and create equivalent permeability structures. Fault trace patterns mapped at the ground surface provide a foundation for creating synthetic fault trace maps using a stochastic procedure conditioned by the outcrop data. Conventional simulations of petroleum production from a 900 by 900 m sub-domain within the reservoir analog illustrate the possible influence of faults and fractures on production. The consequences of incorporating the impact of different stress states (e.g., extension, compression or lithostatic) are also explored. Simulating multiphase fluid flow using a discrete fracture, finite element simulator illustrates how faults acting as conduits might be poorly represented by the upscaling procedures used to assign equivalent permeability values within reservoir models. The parallelized reservoir simulators developed during this project provide a vehicle to evaluate when it might be necessary to incorporate very fine scale grid networks in conventional reservoir simulators or to use finely gridded discrete fracture reservoir simulators.

  12. Sediment Dynamics and the Burial and Exhumation of Bedrock Reefs as Elucidated by High-resolution Repetitive Sonar Surveys: Northern Monterey Bay, CA (United States)

    Storlazzi, C. D.; Fregoso, T. A.; Golden, N. E.; Finlayson, D. P.


    Two high-resolution bathymetric and acoustic backscatter sonar surveys were conducted along the energetic emergent inner shelf of northern Monterey Bay, CA, USA, in the fall of 2005 and the spring of 2006 to determine the impact of winter storm waves, beach erosion, and river floods on biologically-important bedrock reef habitats. The surveys extended from water depths of 4 m to 22 m and covered an area of 3.14 km2, of which 45.8% was bedrock, gravel, and coarse-grained sand and 54.2% was fine-grained sand. Our analysis of the bathymetric and acoustic backscatter data demonstrates that during the 6 months between surveys, 11.4% of the study area was buried by fine-grained sand while erosion exposed of bedrock or coarse-grained sand over 26.5% of the study area. The probability of burial decreased with increasing water depth and rugosity; the probability of exhumation increased with increasing seabed slope and rugosity. Much of the detected change was at the boundary between bedrock and unconsolidated sediment due to burial or exhumation of bedrock. In a number of cases, however, the change in seabed character was apparently due to fluctuations in sediment grain size, where scour exposed what appeared to be an underlying coarser-grained lag or fine-grained sand buried coarser-grained sand. These findings suggest that, in some places, (a) single acoustic surveys typically employed for geologic characterization and/or habitat mapping may not adequately characterize the geomorphology and sedimentologic nature of rocky, energetic inner shelves, and (b) burial and exhumation likely play a role in the life history of the numerous organisms that inhabit these reefs and thus information on the frequency and magnitude of such processes may better constrain our understanding of physical controls on benthic species' distribution patterns.

  13. Timing of subduction and exhumation in a subduction channel: Evidence from slab melts from La Corea Mélange (eastern Cuba) (United States)

    Blanco-Quintero, I. F.; Rojas-Agramonte, Y.; García-Casco, A.; Kröner, A.; Mertz, D. F.; Lázaro, C.; Blanco-Moreno, J.; Renne, P. R.


    High pressure igneous rocks (tonalites), generated by partial melting of subducted basaltic rocks accreted to the mantle wedge, are present in the La Corea serpentinite-matrix mélange (eastern Cuba) as centimeter- to meter-sized blocks and as concordant to crosscutting veins within high-pressure parent amphibolite blocks. The slab melts have adakitic signatures, in agreement with formation after partial melting of metabasite. Thermobarometric calculations indicate 620-680 °C and 13-15 kbar during crystallization of tonalites and down to 250-300 °C, 6 kbar during retrogression, indicating counter-clockwise P-T paths (hot subduction-cool exhumation). Free water required for melting of amphibolite at moderate temperature (700-750 °C) and moderate pressure (13-16 kbar) close to the wet basaltic solidus is inferred to have been provided after dehydration of sediments, altered basaltic crust and serpentinite of the subducting Proto-Caribbean lithosphere. Single zircon (SHRIMP) and phengite 40Ar/39Ar age data constrain the P-T-t evolution of the mélange from the timing of crystallization of melts at ~ 110-105 Ma to cooling at ~ 87-84 Ma, ca. 350 °C, ca. 9 kbar. These figures are consistent with subduction of an oblique ridge, shortly before 115 Ma. Furthermore, our data indicate very slow exhumation (ca. 1 mm/yr) in the subduction channel during the oceanic convergence stage (120-70 Ma) until final fast exhumation to the surface occurred at 70-65 Ma during a regional arc-platform collision event.

  14. 滇西石鼓杂岩南部早白垩世以来剥露隆升的锆石和磷灰石裂变径迹证据%The exhumation and uplift of the southern Shigu complex since Early Cretaceous evidenced by zircon and apatite fission track

    Institute of Scientific and Technical Information of China (English)

    陈小宇; 刘俊来; 吴文斌


    石鼓杂岩位于青藏高原东南缘经历了多期变质变形作用叠加。为了揭示杂岩体的低温热演化与浅部剥露历史,采集了石鼓杂岩南段石鼓镇-拉巴支村剖面变质岩中的锆石和磷灰石,开展裂变径迹分析。结果表明,石鼓杂岩从早白垩世(133~145Ma)到渐新世(31Ma)经历了一次缓慢的剥露(1.08℃/Ma),而从渐新世开始,其南部经历了较快速的剥露过程(3.23℃/Ma)。磷灰石热史模拟也反映出第二阶段较为快速的冷却过程。结合区域构造分析认为,拉萨与羌塘板块碰撞的远程效应影响早白垩世以来藏东地区地壳结构的调整,导致石鼓杂岩南部出现了第一阶段的剥露作用;而印度与欧亚板块碰撞与后碰撞过程对于石鼓杂岩的新生代剥露具有重要影响。%The Shigu complex lies on the southeastern margin of the Tibetan Plateau, and is mainly distributed in Shigu and Zhongdi⁃an areas. The complex has experienced polyphase superposition of metamorphism and deformation. In order to reveal the low tem⁃perature thermal evolution and exhumation history at the shallow crustal level of the complex and correctly understand the exhuma⁃tion and tectonic evolution of the metamorphic dome in eastern Tibet, the authors collected zircon and apatite fission track samples for the fission track analysis along the Shigu Town-Labazhi section. The analytical results show that the Shigu complex firstly experi⁃enced a slow cooling and exhumation from Early Cretaceous (133~145Ma) to Oligocene (31Ma), and a relatively rapid cooling pro⁃cess started from Oligocene. Time-temperature history simulated by inverse modeling of apatite fission track also reflects a relatively rapid cooling process at the second stage. From regional structural analysis, it is suggested that the far-field effects of the collision be⁃tween the Lhasa and Qiangtang plates may have strongly affected the Early Cretaceous

  15. Petrology of HP/LT metapelitic rocks of an accretionary wedge, the Central Pontides, Turkey: evidence for tectonic stacking and syn-subduction exhumation (United States)

    Aygül, Mesut; Okay, Aral; Oberhänsli, Roland


    Cretaceous HP/LT chloritoid-bearing metapelitic rocks crop out widely in the central part of the Pontides, northern Turkey. They are associated with eclogite to blueschist-facies metabasites and represent deep levels of an underplated subduction-accretion complex, which is tectonically overlain by low-grade HP phyllite/metasandstone intercalation along an extensional shear zone. Close to the shear zone, the footwall micaschists consist of quartz, phengite, paragonite, chlorite, rutile with syn-kinematic albite porphyroblast formed by pervasive shearing during exhumation. This type of micaschists is tourmaline-bearing and their retrograde nature suggests high-fluid flux along shear zones. Peak metamorphic assemblages are partly preserved in the chloritoid-micaschist farther away from the shear zone. Three peak metamorphic assemblages are identified and their PT conditions are constrained by pseudosections produced by Theriak-Domino and by Raman spectra of carbonaceous material: 1) garnet-chloritoid-glaucophane with lawsonite pseudomorphs (P: 17.5 ± 1 Kbar, T: 390-450 °C) 2) chloritoid with glaucophane pseudomorphs (P: 16-18 Kbar, T: 475 ± 40 °C) and 3) relatively high-Mg chloritoid (17%) with jadeite pseudomorphs (22-25 Kbar; T: 440 ± 30 °C) in addition to phengite, paragonite, quartz, chlorite, rutile. The last mineral assemblage is interpreted as transformation of the chloritoid + glaucophane assemblage to chloritoid + jadeite paragenesis with increasing pressure. Absence of tourmaline suggests that the chloritoid-micaschist did not interact with B-rich fluids during zero strain exhumation. Peak metamorphic assemblages and PT estimates suggest tectonic stacking within wedge with different depths of burial. 40Ar/39Ar phengite age of a pervasively sheared footwall micaschist is constrained to 100.6 ± 1.3 Ma and that of a chloritoid-micaschist is constrained to 91.8 ± 1.8 Ma suggesting exhumation during on-going subduction. Coupling and exhumation of the

  16. Buoyancy-Driven Heat Transfer During Application of a Thermal Gradient for the Study of Vapor Deposition at Low Pressure Using and Ideal Gas (United States)

    Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.


    A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is positioned vertically. The ground-based experiments are sufficient preliminary tests of theory and should be of significant interest regarding vapor deposited films in microgravity.

  17. Development and Assessment of CFD Models Including a Supplemental Program Code for Analyzing Buoyancy-Driven Flows Through BWR Fuel Assemblies in SFP Complete LOCA Scenarios (United States)

    Artnak, Edward Joseph, III

    This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-ofcoolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives. Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based controlvolume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy.

  18. Dynamics of the Leeuwin Current: Part 2. Impacts of mixing, friction, and advection on a buoyancy-driven eastern boundary current over a shelf (United States)

    Benthuysen, Jessica; Furue, Ryo; McCreary, Julian P.; Bindoff, Nathaniel L.; Phillips, Helen E.


    The boundary currents over the Western Australian continental shelf and slope consist of the poleward flowing Leeuwin Current (LC) and the equatorward flowing Leeuwin Undercurrent (LUC). Key properties of the LC are its poleward strengthening, deepening to the south, and shelfbreak intensification. The alongshore flow reverses direction below about 300 m, forming the LUC at greater depths. To investigate the processes that cause these features, we obtain solutions to an idealized, regional ocean model of the South Indian Ocean. Solutions are forced by relaxing surface density to a prescribed, meridionally varying density profile ρ*(y) with a timescale of δt. In addition, vertical diffusion is intensified near the ocean surface. This diffusion establishes the minimum thickness over which density is well-mixed. We define this thickness as the “upper layer”. Solutions are obtained with and without a continental shelf and slope off Western Australia and for a range of values of δt and mixing parameters. Within this upper layer, there is a meridional density gradient that balances a near-surface, eastward geostrophic flow. The eastward current downwells near the eastern boundary, leading to westward flow at depth. The upper layer's meridional structure and zonal currents crucially depend on coastal processes, including the presence of topography near the eastern boundary. Kelvin waves inhibit the upper layer from deepening at the coast. Rossby waves propagate the coastal density structure offshore, hence modifying the interior currents. A comparison of the solutions with or without a continental shelf and slope demonstrate that topographic trapping of Rossby waves is a necessary process for maintaining realistic eastern boundary current speeds. Significant poleward speeds occur only onshore of where the upper layer intersects the slope, that is, at a grounding line. Its poleward transport increases when surface-enhanced vertical mixing is applied over a greater depth. When the timescale δt is sufficiently short, the poleward current is nearly barotropic. The current's spatial structure over the shelf is controlled by horizontal mixing, having the structure of a Munk layer. Increasing vertical diffusion deepens the upper layer thickness and strengthens the alongshore current speed. Bottom drag leads to an offshore flow along the bottom, reducing the net onshore transport and weakening the current's poleward acceleration. When δt is long, poleward advection of buoyancy forms a density front near the shelf break, intensifying poleward speeds near the surface. With bottom drag, a bottom Ekman flow advects density offshore, shifting the jet core offshore of the shelf break. The resulting cross-shelf density gradient reverses the meridional current's direction at depth, leading to an equatorward undercurrent.

  19. Fatal nosocomial Legionnaires' disease: relevance of contamination of hospital water supply by temperature-dependent buoyancy-driven flow from spur pipes. (United States)

    Patterson, W J; Seal, D V; Curran, E; Sinclair, T M; McLuckie, J C


    The investigation, epidemiology, and effectiveness of control procedures during an outbreak of Legionnaires' disease involving three immunosuppressed patients are described. The source of infection appeared to be a network of fire hydrant spurs connected directly to the incoming hospital mains water supply. Removal of these hydrants considerably reduced, but failed to eliminate, contamination of water storage facilities. As an emergency control procedure the incoming mains water was chlorinated continuously. Additional modifications to improve temperature regulation and reduce stagnation also failed to eliminate the legionellae. A perspex test-rig was constructed to model the pre-existing hospital water supply and storage system. This showed that through the hydraulic mechanism known as 'temperature buoyancy', contaminated water could be efficiently and quickly exchanged between a stagnant spur pipe and its mains supply. Contamination of hospital storage tanks from such sources has not previously been considered a risk factor for Legionnaires' disease. We recommend that hospital water storage tanks are supplied by a dedicated mains pipe without spurs.

  20. K-Ar dating of late Mesozoic volcanism and geochemistry of volcanic gravels in the North Huaiyang Belt, Dabie orogen: Constraints on the stratigraphic framework and exhumation of the northern Dabie orthogneiss complex

    Institute of Scientific and Technical Information of China (English)


    Two eruption episodes are identified through systematic field investigations and K-Ar dating of the lateMesozoic volcanic rocks in the North Huaiyang belt (NHB),Dabie orogenic belt, of which the earlier volcanic suitetermed Maotanchang Fm. (Fm.) occurring at Jinzhai,Xianhualing and Maotanchang, etc., was erupted from 149Ma to 138 Ma. The other named Xiaotian Fm. mainly dis-tributed at Xiaotian, Shucheng, etc., was formed between132 Ma and 116 Ma. During the eruption gap of the two vol-canic suites deposited a volcano-sedimentary conglomeratelayer, which are composed of the multi-compositional gravels, including the North Dabie orthogneiss complex (NDOC),volcanic gravels, etc. These volcanic gravels in the con-glomerate layer show identical geochemical and isotopic compositions (87Sr/86Sr(t) =0.7084-0.7092, (Nd (t) = 21.8-24.4) to the Maotanchang Fm. volcanic rocks (87Sr/86Sr = 0.7086-0.7102, (Nd = 19.2-24.4), but significantly distinct from those of Xiaotian Fm. (87Sr/86Sr = 0.7076-0.7084, (Nd = 17.2 - 19.2). K-Ar dating results of its underlying andoverlying volcanic sequences indicate that the conglomerate layers were deposite d at ~135 Ma. This suggests that the NDOC was rapidly exhumed to the surface dur ing or shortly before ~135 Ma and became the important provenance of the late Me sozoic volcano-sedimentary basins in the NHB. In combination with the regional v olcano-sedimentary correlation, we divided the Mesozoic stratigraphic sequence i n the NHB from base to top into Fanghushan Fm. (>160 Ma), Yuantongshan Fm. (/mid dle- lower segment of Sanjianpu Fm.) (160-149 Ma), Maotanchang Fm. (/Zhougongsh an Fm./upper segment of Sanjianpu Fm./Fenghuangtai Fm.) (149-135 Ma) and Xiaoti an Fm. (/Baidafan Fm./Heshidu Fm.) (135-116 Ma).

  1. Seismic slip at the base of the seismogenic layer along the exhumed extensional Oligocene Trois Villes Fault (Western Italian Alps) (United States)

    Bistacchi, A.; Gatta, D.; Grizzetti, R.; Pennacchioni, G.


    The characterisation of fault rocks from exhumed faults is of paramount importance in fault and earthquake mechanics, since these rocks might provide constraints for models of seismic rupture initiation and propagation. The Trois Ville Fault is a major Oligocene extensional fault of the internal NW Alps, showing a cumulative displacement of c.a. 1 km evidenced by the offset boundary between Austroalpine gneisses (hangingwall) and Piedmont calcschists (footwall). Fault rocks consist of greenschist mylonitic gneiss (from an early stage), green indurated cataclasites, which constitute the 2-10 m thick core zone, and a thin (c.a. 10 cm) but extremely continuous layer of polycyclic pseudotachylytes which mark a strongly localised principal slipping zone. Pseudotachylytes lack distinctive features such as glass, microlites-spherulites, etc., but show a distinctive mineralogy of the melt-derived very fine-grained matrix, which is almost entirely constituted by monoclinic K-feldspar (low sanidine crystallised at ca. 990°C and partly ordered as far as 500- 700°C). This matrix is composed by very small crystals (0.5-5 μm), organised in aggregates and dendritic snowflake-like aggregates which might be explained by sintering or synneusis processes. The high crystallization T implies that pseudotachylytes derive from frictional melting of ultracataclasites (possibly incoherent, hence a fault gouge, at the time of deformation) near the brittle plastic transition (250- 300°C and 8-10 km). Hence, a new diagnostic criterion for frictional melting, based on crystallographic analysis, is introduced in this work. The melt mainly derived from phyllosilicates (muscovite and minor chlorite; Tmelt c.a. 750°C) and evidences of superheating may be envisaged (partial assimilation of albite and quartz; T > c.a. 1300°C). This points to a considerable seismic slip after the onset of frictional melting and to an efficient melting lubrication process in this kind of fault rocks

  2. Intermediate-depth Fracturing of Oceanic Lithosphere in Subduction Zones: Memories from Exhumed High-Pressure Ophiolites (United States)

    Angiboust, Samuel; Oncken, Onno; Agard, Philippe


    Understanding processes acting along the subduction interface is crucial to assess lithospheric scale coupling between tectonic plates and mechanisms causing intermediate-depth seismicity. Despite a wealth of geophysical studies aimed at better characterizing/localizing this seismicity, we still critically lack constrains on processes triggering fracturing in regions (40-100km depths; T > 400°C) where deformation is expected to be achieved by plastic flow. We herein attempt to bridge this gap by providing a review of available evidence from brittle deformation patterns in exhumed High Pressure (HP) ophiolites, together with some new, critical observations. Field examples from various ophiolitic terranes (New-Caledonia, W. Alps, Tian Shan…) indicate that brittle deformation under HP conditions generally implies vein filling and precipitation of HP minerals, probably under very high pore fluid pressure conditions. Coalescence of such vein networks could explain some of the seismic events recorded along the fluid-rich subduction interface region. By contrast, HP pseudotachylites (though reported in only few localities so far) are apparently restricted to somehow deeper slab regions where fluid-deficient conditions are prevalent (Corsica, Zambia, Voltri?). The recent discovery of eclogite breccias, found as m-sized dismembered fragments within an eclogite-facies shear zone from the Monviso area (W. Alps), provides a new opportunity to study the genesis of intermediate-depth earthquakes. We herein argue that these eclogite breccias constitute unique remnants from an ancient fault zone associated with intraslab, intermediate-depth seismicity at ca. 80 km depth. The breccia is internally made of 1-10 cm-sized rotated fragments of eclogite mylonite cemented by an eclogite-facies matrix attesting of fracturing and fault sealing under lawsonite-eclogite facies conditions (550°C, 2.5 GPa) during subduction of the Tethyan seafloor. Textural observations and polyphased

  3. Hot, Fast Faults: Evidence for High-Temperature Slip on Exhumed Faults, and Insights into Seismic Slip Processes (United States)

    Evans, J. P.; Ault, A. K.; Janecke, S. U.; Prante, M. R.


    Microstructural and geochemical techniques combined with prior observations of naturally occurring faults provide insights into slip rates and slip dimensions of seismicity. We review four indicators for high coseismic paleotemperatures in brittle to semi-brittle faults from a wide range of tectonic settings with mm to km of slip. Thin, high-gloss, Fe-rich slip surfaces indicate high-temperature slip occurred on mm- to m-scales. Elliptical and circular zones of concentric iridescence indicate localized sites of elevated temperature that may be caused by heating at asperity contacts. The surface iridescence is associated with changes in Fe oxidation states detected by X-Ray photoelectron spectroscopy. Minimum temperature increases of 300 °C above ambient are supported by geochemical arguments and up to 800 °C are supported by analogs to high-speed friction experiments in steels and ceramics firing in reduced conditions. The presence of clay-rich foliated fault-related rocks, and the presence of nm- to mm-thick clay coatings indicate that syn-kinematic endothermic reactions occur at a range of scales. We suggest these features reflect temperature increases of ≥100-200 °C for activation energy required to drive the clay alteration is sourced from seismic energy and Schleicher-van der Pluijm-type slip surfaces to record instantaneous slip. Dense, low porosity planar porcelainite zones mm- to cm-thick along fault surfaces are the result of sintering of quartz-clay-feldspar mixtures and indicate T≥1000 °C localized along the surfaces, the result of post-slip cooling. Highly indurated, ultrafine fault-related rocks often consists of comminuted grains, vein fragments, and neocrystallized grains that represent retrograde cooling or alteration after peak heating. These observations and those of other recent workers indicate that many naturally occurring exhumed faults record elevated temperatures. In many cases, careful observations can delineate fault slip

  4. Mineral chemistry, P-T-t paths and exhumation processes of mafic granulites in Dinggye, Southern Tibet

    Institute of Scientific and Technical Information of China (English)

    LIU; Shuwen; ZHANG; Jinjiang; SHU; Guiming; LI; Qiugen


    the amphibolite facies metamorphism with pressure of 0.4 to 0.75 GPa and temperature at between 660 and 700℃. These construct P-T paths from crustal subduction overthickening to tectonic uplift tectonothermal evolution. The mineral chemical characteristics and P-T condition at every metamorphic stage of these granulites indicate that these rocks experienced the eclogite facies metamorphism during the early stage. Subsequently, these mafic granulites underwent the three-stage exhumation of the eclogite facies tectonic uplift, isostatic uplift related to the transformation from eclogite/high-pressure granulite to granulite facies and extensional uplift.

  5. Rapid shallow breathing (United States)

    Tachypnea; Breathing - rapid and shallow; Fast shallow breathing; Respiratory rate - rapid and shallow ... Shallow, rapid breathing has many possible medical causes, including: Asthma Blood clot in an artery in the lung Choking Chronic obstructive ...

  6. Identification of exhumed remains of fire tragedy victims using conventional methods and autosomal/Y-chromosomal short tandem repeat DNA profiling. (United States)

    Calacal, Gayvelline C; Delfin, Frederick C; Tan, Michelle Music M; Roewer, Lutz; Magtanong, Danilo L; Lara, Myra C; Fortun, Raquel dR; De Ungria, Maria Corazon A


    In a fire tragedy in Manila in December 1998, one of the worst tragic incidents which resulted in the reported death of 23 children, identity could not be established initially resulting in the burial of still unidentified bodies. Underscoring the importance of identifying each of the human remains, the bodies were exhumed 3 months after the tragedy. We describe here our work, which was the first national case handled by local laboratories wherein conventional and molecular-based techniques were successfully applied in forensic identification. The study reports analysis of DNA obtained from skeletal remains exposed to conditions of burning, burial, and exhumation. DNA typing methods using autosomal and Y-chromosomal short tandem repeat (Y-STR) markers reinforced postmortem examinations using conventional identification techniques. The strategy resulted in the identification of 18 out of the 21 human remains analyzed, overcoming challenges encountered due to the absence of established procedures for the recovery of mass disaster remains. There was incomplete antemortem information to match the postmortem data obtained from the remains of 3 female child victims. Two victims were readily identified due to the availability of antemortem tissues. In the absence of this biologic material, parentage testing was performed using reference blood samples collected from parents and relatives. Data on patrilineal lineage based on common Y-STR haplotypes augmented autosomal DNA typing, particularly in deficiency cases.

  7. 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 (United States)

    Ono, Takuya; Yoshida, Hidekazu; Metcalfe, Richard


    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.

  8. Building and exhumation of the Western Carpathians: New constraints from sequentially restored, balanced cross sections integrated with low-temperature thermochronometry (United States)

    Castelluccio, Ada; Mazzoli, Stefano; Andreucci, Benedetta; Jankowski, Leszek; Szaniawski, Rafał; Zattin, Massimiliano


    Western Carpathian orogeny has been the subject of intense scientific debate due to the occurrence of enigmatic features, leading several authors to provide contrasting geological models. In this paper, a new interpretation for the tectonic evolution of the Western Carpathians is provided based on the following: (i) an analysis of the stratigraphy of the Mesozoic-Tertiary successions across the thrust belt domains, (ii) a reappraisal of the stratigraphy and sedimentology of the "tectonic mélange" (i.e., the so-called Pieniny Klippen Belt) marking the suture between the Inner and Outer Carpathians, and (iii) the construction of a series of balanced and restored cross sections, validated by 2-D forward modeling. Our analysis provides a robust correlation of the stratigraphy from the Outer to the Inner Carpathians, independently of the occurrence of oceanic lithosphere in the area, and allows for the reinterpretation of the tectonic relationships among the Inner Carpathians, the Outer Carpathians, and the Pieniny Klippen Belt and the exhumation mechanisms affecting this orogenic belt. In order to constrain the evolution during the last 20 Ma, our model also integrates previously published and new apatite fission track and apatite (U-Th-Sm)/He data. These latter indicate a middle-late Miocene exhumation of the Pieniny Klippen Belt. In this study, the recent regional uplift of the Pieniny Klippen Belt is described for the first time using a 2-D kinematic model for the tectonic evolution of the Western Carpathians.

  9. Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif, China

    Institute of Scientific and Technical Information of China (English)


    A detailed tectonic analysis demonstrates that the present observed regional tectonic configuration of the ultrahigh-pressure metamorphic terrane in the Dabie massif was mainly formed by the extension processes of the post-Indosinian continent-continent oblique collision between the Sino-Korean and Yangtze cratons and ultrahigh-pressure metamorphism (UHPM). The configuration is characterized by a regional tectonic pattern similar to metamorphic core complexes and by the development of multi-layered detachment zones. On the basis of the identification of compressional and extensional fabrics, it is indicated that the exhumation and uplift of ultrahigh-pressure (UHP) metamorphic rocks from the mantle depth to the surface can be divided into at least three different decompression retrogressive metamorphism and tectonic deformation stages, in which the subhorizontal crustal-scale extensional flow in the middle-lower crust under amphibolite facies conditions is an important geodynamic process in the exhumation of UHP metamorphic rocks. Moreover, the extensional flow is probably driven by delamination and magmatic underplating of thickened lithospheric mantle following the continental oblique collision.

  10. Crustal shortening, exhumation, and strain localization in a collisional orogen: The Bajo Pequeño Shear Zone, Sierra de Pie de Palo, Argentina (United States)

    Garber, Joshua M.; Roeske, Sarah M.; Warren, Jessica; Mulcahy, Sean R.; McClelland, William C.; Austin, Lauren J.; Renne, Paul R.; Vujovich, Graciela I.


    The Bajo Pequeño Shear Zone (BPSZ) is a lower-crustal shear zone that records shortening and exhumation associated with the establishment of a new plate boundary, and its placement in a regional structural context suggests that local- to regional-scale strain localization occurred with progressive deformation. A kilometer-scale field and analytical cross section through the ~80 m thick BPSZ and its adjacent rocks indicates an early Devonian (405-400 Ma) phase of deformation on the western margin of Gondwanan continental crust. The earliest stages of the BPSZ, recorded by metamorphic and microstructural data, involved thrusting of a hotter orthogneiss over a relatively cool pelitic unit, which resulted in footwall garnet growth and reset footwall white mica 40Ar/39Ar ages in proximity to the shear zone. Later stages of BPSZ activity, as recorded by additional microstructures and quartz c-axis opening angles, were characterized by strain localization to the center of the shear zone coincident with cooling and exhumation. These and other data suggest that significant regional tectonism persisted in the Famatinian orogenic system for 60-70 million years after one microplate collision (the Precordillera) but ceased 5-10 million years prior to another (Chilenia). A survey of other synchronous structures shows that strain was accommodated on progressively narrower structures with time, indicating a regional pattern of strain localization and broad thermal relaxation as the Precordillera collision evolved.

  11. 磷灰石裂变径迹研究新疆阿尔泰山南缘剥露历史及古地形再造%Apatite Fission Track Analyses of Exhumation History and Antiquated Topography Reconstruction in the Southern Margin of Altai, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    宋高; 袁万明; 赵文菊; 刘海涛


    Thirteen apatite samples from the Altai region were employed to reveal the history of uplifting and exhumation using fission track method and to reconstruct antiquated topography.History of cooling evolution is characterized with a model of three stages.Stage one from 120 Ma to 80 Ma or 70 Ma records the highest temperature and is in the bottom temperature of apatite fission track anneal strip,with THE dominant temperature of higher than 100℃.During late Late Cretaceous and early Paleogene periods,the Altai region had no distinct tectonic activity but just weak lifting and exhumation.Stage two lasting from 80~70 Ma to 20 Ma records rapid cooling with temperature decreasing from 120~100℃ to 35~30℃.Since mid-Palegene,especially from mid-late Miocene,Himalayan movement resulted in strong uplift and exhumation,with mountains uplifting and basins relatively lowering.The final stage from 30 Ma to 20 Ma and to present records slow cooling process,with temperature going down from 35 ~ 30℃ to the temperature of current Earth's surface (an average temperature of 20℃).The uplift rates of three stages are 0.025 mm/a,0.027 mm/a and 0.02 mm/a,respectively,while uplift magnitude of the three are correspondingly 1.14 km,1.34 km and 0.43 km.The surface uplift ranges between 634 and 2394 m.Average values for exhumation and uplift are 2168 m and 3318 m,and the balance of them (1150 m) is the average height of the mountain today.%本文应用裂变径迹技术对阿尔泰地区13个磷灰石裂变径迹样品进行分析研究,揭示了该地区的隆升剥露历史,并进行了古地形再造.热历史演化模式具有3个阶段的特征:①约120~80 Ma至70 Ma,温度较高,处于磷灰石裂变径迹退火带底部温度,主体高于100℃,晚白垩世末期和早第三纪初期,阿尔泰地区构造运动不明显,仅有微弱的升降运动,均夷作用显著;②从80~70 Ma至30~20 Ma,快速冷却,温度由85~75℃降至35~30℃,晚第三纪,自中新

  12. Effects of Caribbean oceanic plateau shallow subduction on topographic uplift and exhumation of the northwestern Maracaibo block, Colombia (United States)

    Sanchez, J.; Mann, P.


    The Maracaibo block in the northwestern South America is a triangular lithotectonic terrane bounded on its western edge by the Santa Marta-Bucaramanga left-lateral strike-slip fault and the Oca-Ancon right-lateral strike-slip fault on its northern edge. These faults bound two isolated Andean ranges within the Maracaibo block: the Sierra de Santa Marta massif (SSM) in the east whose highest point is 5700 m ASL, and the Serrania del Perija (SP) to the west, whose highest point is 3600 m ASL. The two ranges are separated by an elongate, NNE-trending sedimentary basin, the Cesar-Rancheria basin (CRB). Previous thermochronological studies in the region have shown three discrete exhumation pulses from Paleocene to Miocene that are attributed to various collisional and strike events along the Caribbean margin. However the tectonic origin of the late Neogene deformation that produced the isolated, high topography of the SSM and SP has remained unclear. To establish patterns of recent uplift and associate them with a specific tectonic mechanism affecting the area, we integrated the following results: 1) analysis of stream profiles using channel normalized steepness indices and identification of slope-break knickpoints as indicators of rock uplift; 2) integration of observations from geological maps; 3) interpretation of 2D onland seismic profiles; 4) analysis of published thermochronological data; and 5) analysis of 1D/2D basin model based on well subsidence analysis from the CRB. Our results from the extraction of 550 long stream profiles from different watersheds for the SSM and SP reveal: 1) undisturbed profiles at western flank of the northern SP characterized by a few vertical-step knickpoints associated with lithology changes; in contrast the eastern flank of the northern SP shows slope-break knickpoints and changes in steepness indices increasing by a factor of ~2, all indicative of active fault control affecting this area; 2) disturbed profiles in the elevated

  13. Integrated provenance-detrital thermochronology studies in ANDRILL AND-2A drill core: first evidence of an Oligocene exhumation episode (McMurdo Sound, Antarctica) (United States)

    Zattin, M.; Talarico, F. M.; Sandroni, S.


    An integrated investigation including provenance analysis of the gravel-fraction and detrital apatite fission-track (AFT) thermochronology on the AND-2A core provides new results to constrain the exhumation history of source regions and the reconstruction of sediment provenance models in the Ross Embayment in Late Cenozoic time. All the AFT ages, from 20 samples, evenly distributed in the uppermost 1000 m of the core, indicate that the entire succession originated from a source that exhumed in the Oligocene/Late Eocene time. In fact, most of the grains in nearly all the samples can be grouped into a youngest grain-age component (P1) in the range between 21.7 Ma and 43.4 Ma. However, most of the samples show more than one population, documenting the presence of multiple source areas in some periods of the basin history. On the other hand, the presence in some of the samples of a unique peak suggests a limited drainage system, as indicated by the petrographic data. The AFT data indicate the presence of active tectonics at the end of the Oligocene, therefore suggesting a source of sediments located along the Transantarctic Mountains (TAM) south of the Dry Valleys Block, where bedrock AFT ages indicate an older (Eocene) exhumation phase. Hence, the idea of a structural segmentation of the TAM during the Cenozoic (Wilson, Glob. Plan. Change, 1999) is well supported by these data. Provenance analysis of the gravel fraction highlights significant down-core modal and compositional variations and the occurrence of two main basement clast assemblages, diagnostic of specific source regions and occurring in distinct core sections: a) including marbles, garnet micaschists and diopside schists, suggesting oscillation of "local" glaciers in the on-shore area close to the AND-2A drill site, and b) low-grade metasediments and alkaline granites, indicating oscillations of a most extensive ice sheet/shelf with a clear provenance from the Skelton-Mulock glacier area. These data agree

  14. Sediment dynamics and the burial and exhumation of bedrock reefs along an emergent coastline as elucidated by repetitive sonar surveys: Northern Monterey Bay, CA (United States)

    Storlazzi, C.D.; Fregoso, T.A.; Golden, N.E.; Finlayson, D.P.


    Two high-resolution bathymetric and acoustic backscatter sonar surveys were conducted along the energetic emergent inner shelf of northern Monterey Bay, CA, USA, in the fall of 2005 and the spring of 2006 to determine the impact of winter storm waves, beach erosion, and river floods on biologically-important siliclastic bedrock reef habitats. The surveys extended from water depths of 4 m to 22 m and covered an area of 3.14 km2, 45.8% of which was bedrock, gravel, and coarse-grained sand and 54.2% was fine-grained sand. Our analyses of the bathymetric and acoustic backscatter data demonstrates that during the 6 months between surveys, 11.4% of the study area was buried by fine-grained sand while erosion resulted in the exposure of bedrock or coarse-grained sand over 26.5% of the study area. The probability of burial decreased with increasing water depth and rugosity; the probability of exhumation increased with increasing wave-induced near-bed shear stress, seabed slope and rugosity. Much of the detected change was at the boundary between bedrock and unconsolidated sediment due to sedimentation and erosion burying or exhuming bedrock, respectively. In a number of cases, however, the change in seabed character was apparently due to changes in sediment grain size when scour exposed what appeared to be an underlying coarser-grained lag or the burial of coarser-grained sand and gravel by fine-grained sand. These findings suggest that, in some places, (a) burial and exhumation of nearshore bedrock reefs along rocky, energetic inner shelves occurs over seasonal timescales and appears related to intrinsic factors such as seabed morphology and extrinsic factors such as wave forces, and (b) single acoustic surveys typically employed for geologic characterization and/or habitat mapping may not adequately characterize the geomorphologic and sedimentologic nature of these types of environments that typify most of the Pacific Ocean and up to 50% of the world's coastlines.

  15. Tracking the timing of subduction and exhumation using 40Ar/39Ar phengite ages in blueschist- and eclogite-facies rocks (Sivrihisar, Turkey) (United States)

    Fornash, Katherine F.; Cosca, Michael A.; Whitney, Donna L.


    Geochronologic studies of high-pressure/low-temperature rocks can be used to determine the timing and rates of burial and exhumation in subduction zones by dating different stages of the pressure-temperature history. In this study, we present new in situ UV laser ablation 40Ar/39Ar phengite ages from a suite of lawsonite blueschist- and eclogite-facies rocks representing different protoliths (metabasalt, metasediment), different structural levels (within and outside of a high-strain zone), and different textural positions (eclogite pod core vs. margin) to understand the timing of these events in an exhumed Neo-Tethyan subduction zone (Sivrihisar Massif, Tavşanlı Zone, Turkey). Weighted mean in situ 40Ar/39Ar ages of phengite from the cores of lawsonite eclogite pods (90-93 Ma) are distinctly older than phengite from retrogressed, epidote eclogite (82 ± 2 Ma). These ages are interpreted as the age of peak and retrograde metamorphism, respectively. Eclogite records the narrowest range of ages (10-14 m.y.) of any rock type analyzed. Transitional eclogite- and blueschist-facies assemblages and glaucophane-rimmed lawsonite + garnet + phengite veins from eclogite pod margins record a much wider age range of 40Ar/39Ar ages (~20 m.y.) with weighted mean ages of ~91 Ma. Blueschists and quartzites record more variable 40Ar/39Ar ages that may in part be related to structural position: samples within a high-strain zone at the tectonic contact of the HP rocks with a meta-ultramafic unit have in situ UV laser ablation 40Ar/39Ar ages of 84.0 ± 1.3-103.7 ± 3.1 Ma, whereas samples outside this zone range to older ages (84.6 ± 2.4-116.7 ± 2.7 Ma) and record a greater age range (22-38 m.y.). The phengite ages can be correlated with the preservation of HP mineral assemblages and fabrics as well as the effects of deformation. Collectively, these results show that high-spatial resolution UV laser ablation 40Ar/39Ar phengite data, when considered in a petrologic and structural

  16. 40Ar/39Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai,East China

    Institute of Scientific and Technical Information of China (English)

    LI Jinyi; YANG Tiannan; CHEN Wen; ZHANG Sihong


    Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai regionof East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlierductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittledeformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these twoevents. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, whichare structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicatingthat the earlier event of the ampibolite-facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating oforiented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of213.1 ±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatiticbiotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 203.4±0.3 Ma,203.6±0.4 Ma and 204.8±2.2 Ma, and isochron ages of 204.0±2.0 Ma, 200.6±3.1 Ma and 204.0±5.0 Ma, respectively,implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 204 Ma). The integration of these data with previous chronological ageson the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocksin the area were exhumed at the rate of 3-4 km/Ma from the mantle (about 80-100 km below the earth's surface at about240 Ma) to the lower crust (at the depth of about 20-30km at 220 Ma), and at the rate of 1-2 km/Ma to the middle crust (atthe depth of about 15 km at 213 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km deep

  17. The Formation Mechanism of Coesite Far from Equilibrium Phase-Boundary and the Physical Foundation of Hypothesis of Plate Subduction Exhumation in the Earth%远离平衡相边界的柯石英形成机制及板块折返假说的物理基础

    Institute of Scientific and Technical Information of China (English)



    physics,it is very hard to subduct solid continental crust rock into solid crust—mantle rock. Chopin firstly evaded the original driving force, and further,drew a constant equal sign without scientific basis between the two events of the coesite and diamond ultrahigh pressure metamorphic rock found in the Earth's crust and the stable phase produced in the mantle or the deep subduction, and then again rose up to a “paradigm” height that had misled need no original driving force of research. Since the introduction of the hypothesis of plate subduction—exhumation so far, the original driving force of plate subduction—exhumation has always not been resolved. Uneven solid Earth is a natural high-temperature high-pressure system, in order to preserve the coesite, a high-temperature high-pressure phase of quartz, the rapid cooling rate of plate is requested over 40℃ / Ma that should be comparable with the laboratory critical rate of quenching under pressure-keeping (which requires not less than (0. 5 ~ 1.0) x 102℃ / s) , however,there is a huge differential in 1013 order of magnitude for both cases. From the lab phase change regularity of high-temperature high-pressure, such extremely slow cooling rates of plate exhumation is difficult to keep the living coesite. Conversely, in order to make plate exhumation speed reached laboratory critical cooling rate of keeping coesite quenching under pressure, the speed ( in air) of plate exhumation must achieve 10 ~ 20km/s. This meant that to make a huge amount matter with such great speed fast penetrate and exhumation in the solid medium that needs a giant abnormal rare driving force of exhumation, however, from physics viewpoint it is extremely difficult to achieve. In addition, the four important factors put forward by Chopin, influencing the coesite preserve during turn-back process, still exist many problems,and also could not overcome the above paradoxes. The time of atomic diffusion and chemical reaction in solid

  18. 大别—苏鲁区超高压(UHP)变质岩的多阶段构造折返过程%Multi-Stage Tectonic Exhumation Processes of Ultrahigh-Pressure (UHP) Metamorphic Rocks in the Dabie-Sulu Area, East-Central China

    Institute of Scientific and Technical Information of China (English)

    索书田; 钟增球; 周汉文; 张利; 游振东


    Exhumation processes of ultrahigh-pressure (UHP) metamorphic rocks, by which these deep-seated rocks were rapidly returned from mantle depths of more than 100 km within deep subduction zones into the upper crust and to the surface, are of paramount importance for the understanding of the kinematics and dynamics of convergent plate margins and continental collision belts. At least four large successive stages of the exhumation process of UHP metamorphic rocks in the Dabie-Sulu area, east-central China, mainly based on structural, petrological, geochemical data and available geochronological data, combined with previously regional polyphased deformation analyses, can be distinguished. Massive eclogites recorded the deep continental subduction/collision between the Sino-Korean and Yangtze cratons during the Triassic (~250-230 Ma). The early exhumation occurred after the peak of UHP metamorphism at conditions of up to >3. 1-4. 0 Gpa and 800±50 ℃ , which may correspond to the Dz regional deformation phase and took place at mantle depths, displaying the model of vertical ductile extrusion, within the coesite stability field. The subsequent exhumation stages, corresponding with D3, D4 and D5 regional deformation phase, respectively, and two intermediate tectono-thermal events, I. E. , the formation of the granulite/amphibolite facies symplectite or corona and the generation of extensive partial melting, occurred in crustal levels. Shear zones of an anastomosing rheological type were developed at diffterent stages and depths, indicating that the partitioning of deformation and metamorphism within the UHP metamorphic belt repeated. These imply that the exhumation of the UHP rocks is a complex tectonic process, in response to subduction/collision or extension of the continental crust, and is strongly constrained by a number of internal and external factors of the belt. In particular, fluids play important roles in the exhumation process of UHP rocks in the Dabie

  19. Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif,China

    Institute of Scientific and Technical Information of China (English)

    索书田; 钟增球; 游振东


    A detailed tectonic analysis demonstrates that the present ob served regional tectonic configuration of the ultrahigh-pressure metamorphic terrane in the Da bie massif was mainly formed by the extension processes of the post-lndosinian continent-continent oblique collision between the Sino-Korean and V’angtze cratons and ultrahigh-pressure metamorphism (UHPM). The configuration is characterized by a regional tectonic pattern similar to metamorphic core complexes and by the development of multi-layered detachment zones. On the basis of the identification of compressional and extensional fabrics, it is indicated that the exhumation and uplift of ultrahigh-pressure (UHP) metamorphic rocks from the mantle depth to the surface can be divided into at least three different decompression retrogressive metamo rphism and tectonic deformation stages, in which the subhorizontal crustal-scale extensional flow in the middle-lower crust under amphibolite facies conditions is an important geodynamic process in the exhu

  20. The UHP metamorphic Seve Nappe Complex of the Swedish Caledonides - a new occurrence of the microdiamond-bearing gneisses and their exhumation (United States)

    Klonowska, Iwona; Janák, Marian; Majka, Jarosław; ‎ Froitzheim, Nikolaus; Gee, David G.


    The ultra-high pressure metamorphism (UHPM) in the Seve Nappe Complex of the Swedish Caledonides has been recently recognized within several lithologies including gneisses, eclogites and garnet pyroxenites (e.g. Janák et al. 2013, Klonowska et al. 2014a, Majka et al. 2014). Thermodynamic modelling and thermobarometric calculations indicate peak pressure conditions of >3GPa at c. 800-900°C (reaching the diamond stability field) for eclogites and garnet pyroxenites from northern Jämtland (e.g. Klonowska et al. 2014b). In addition to this, the first microdiamonds were found in paragneisses from the Snasahögarna Mt. in central Jämtland (Majka et al. 2014). Here we report a new discovery of microdiamond together with moissanite (SiC) from one of the world's most famous localities for thrusting, Mount Åreskutan, where long transport distances were recognized already in the 19th century (Törnebohm 1888). Garnet porphyroblasts in gneisses from the Åreskutan Mt. contain abundant mineral inclusions, mainly graphite, carbonates and quartz, together with fluid inclusions of CO2 concentrated in swarms. Among these inclusions three microdiamonds were found in two gneiss samples. In one of the samples moissanite was also discovered. Both minerals were identified by micro-Raman spectroscopy. In addition to these 'swarm' inclusions, biotite, kyanite, rutile, feldspars, zircon, monazite, ±phengite, ±muscovite, ±spinel, ±ilmenite, ±apatite occur in garnets. Phase equilibrium modelling for the phengite-bearing gneiss confirms its UHP history at temperatures of c. 800°C. Recent discoveries of UHP metamorphism within the Seve Nappe Complex derived from the Baltican outer margin (part of the Middle Allochthon) challenged us to present a new tectonic model incorporating exhumation of the deeply subducted continental rocks together with mantle lithosphere peridotites. Majka et al. (2014) introduced a new "under-pressure"-driven exhumation mechanism of rocks buried in

  1. Using Sequential Kinematic and Thermochronometric Modeling to Temporally and Spatially Link Thrust Belt Exhumation with Basin Development in the Bolivian Fold-Thrust-Belt-Foreland Basin System. (United States)

    Rak, A. J.; McQuarrie, N.


    Applying isostasy and erosion to sequentially deformed balanced cross sections links the growth of hinterland structures to the developing foreland basins (FB) adjacent to fold-thrust belts (FTB), adding geologic constraints to modeled exhumation pathways. We sequentially deform the Rio Beni cross section in northern Bolivia (McQuarrie et al., 2008) with kinematic modeling software Move. In our model, topography evolves and basins develop for each model step as deformation, erosion, and isostasy are applied; and are a direct function of the geometry and kinematics of the cross section. The model is constrained by the depth of the foreland and hinterland basins, geology present at the surface, the depth and angle of the decollement, and the shape of the modern observed topography. Topography develops as thrusting occurs and loads the crust, producing a flexural wave and creating accommodation space in adjacent basins. Erosion of material above a newly generated topographic profile unloads the section while basin space is filled. Once the model sufficiently duplicates geologic constraints, a 0.5 km X 0.5 km grid of unique points is deformed with the model and used to determine displacement vectors for each 10 km shortening step. These displacement vectors, in conjunction with a prescribed time interval for each step, determine a velocity field that can be used in a modified version of the advection diffusion modeling software Pecube. Cooling ages predicted using this method are based on deformation rates, geometry, topography, and thermal parameters, and offer insight into possible rates of deformation, erosion, and deposition throughout FTB and FB development. Incorporating erosion, deposition, and isostasy in sequentially deformed balanced cross sections highlights the spatiotemporal aspects of sedimentary wedge propagation, identifies necessary external negative buoyancy affects, and provides additional geologic constraints to modeled exhumation pathways.

  2. From source to sink in central Gondwana: Exhumation of the Precambrian basement rocks of Tanzania and sediment accumulation in the adjacent Congo basin (United States)

    Kasanzu, Charles Happe; Linol, Bastien; Wit, Maarten J.; Brown, Roderick; Persano, Cristina; Stuart, Finlay M.


    Apatite fission track (AFT) and (U-Th)/He (AHe) thermochronometry data are reported and used to unravel the exhumation history of crystalline basement rocks from the elevated (>1000 m above sea level) but low-relief Tanzanian Craton. Coeval episodes of sedimentation documented within adjacent Paleozoic to Mesozoic basins of southern Tanzania and the Congo basin of the Democratic Republic of Congo indicate that most of the cooling in the basement rocks in Tanzania was linked to erosion. Basement samples were from an exploration borehole located within the craton and up to 2200 m below surface. Surface samples were also analyzed. AFT dates range between 317 ± 33 Ma and 188 ± 44 Ma. Alpha (Ft)-corrected AHe dates are between 433 ± 24 Ma and 154 ± 20 Ma. Modeling of the data reveals two important periods of cooling within the craton: one during the Carboniferous-Triassic (340-220 Ma) and a later, less well constrained episode, during the late Cretaceous. The later exhumation is well detected proximal to the East African Rift (70 Ma). Thermal histories combined with the estimated geothermal gradient of 9°C/km constrained by the AFT and AHe data from the craton and a mean surface temperature of 20°C indicate removal of up to 9 ± 2 km of overburden since the end of Paleozoic. The correlation of erosion of the craton and sedimentation and subsidence within the Congo basin in the Paleozoic may indicate regional flexural geodynamics of the lithosphere due to lithosphere buckling induced by far-field compressional tectonic processes and thereafter through deep mantle upwelling and epeirogeny tectonic processes.

  3. Low-temperature thermochronology of northern Baja California, Mexico: Decoupled slip-exhumation gradients and delayed onset of oblique rifting across the Gulf of California (United States)

    Seiler, Christian; Fletcher, John M.; Kohn, Barry P.; Gleadow, Andrew J. W.; Raza, Asaf


    The northern Gulf Extensional Province displays key structural relationships that characterize the magnitude, direction, and timing of Neogene rift-related transtension during the opening of the Gulf of California. Apatite fission track and (U-Th)/He thermochronology from the Sierra San Felipe document moderate cooling (4°C/Myr-7°C/Myr) during the early Paleogene associated with progressive unroofing caused by erosional downwearing of the ancestral Peninsular Ranges. Beginning at ˜45-35 Ma, a period of tectonic quiescence with low cooling rates (≤1°C/Myr) marks the development of a regional Oligocene-Miocene peneplain. Rift-related exhumation began at ˜9-7 Ma and attains ˜2.5 km in the hinges of two antiformal megamullions. Decoupling between exhumation and finite displacement in certain fault segments is explained by vertical deflections associated with extension-perpendicular folding of the fault surfaces. The main faults of the detachment system were active contemporaneously, thus forming a mechanically linked array of large-displacement normal faults in the hanging wall of the Main Gulf Escarpment. The Late Miocene onset of transtension in the Sierra San Felipe suggests that widespread deformation may only have localized in the Gulf Extensional Province between ˜9 and 7 Ma, some ˜3-5 Ma after a major plate reorganization associated with cessation of subduction in the trench to the west. Between ˜12 Ma and ˜9-7 Ma, plate boundary shearing was likely distributed between the continental borderland west of Baja California and the southern Basin and Range province in Mexico.

  4. Rapid response systems update. (United States)

    Winterbottom, Fiona; Castex, Julie; Campbell, Anita


    Rapid response is a mature concept that is undergoing metamorphosis. The ideal structure and function of these safety teams has not yet been realized but new developments in the field of rapid response systems are evolving.

  5. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China:Evidence from apatite fission track analysis

    Institute of Scientific and Technical Information of China (English)

    Wenhao Tang; Zhicheng Zhang; Jianfeng Li; Ke Li; Zhiwen Luo; Yan Chen


    Apatite fission track (AFT) analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0e13.2 mm) mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassiceearly Cretaceous and the OligoceneeMiocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma), recording the earlier rapid uplift phase during the late JurassiceCretaceous, while the ages in the north pied-mont of the Bogda Mountain (namely the northeast part) are younger (<60 Ma), mainly reflecting the later rapid uplift phase in the OligoceneeMiocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  6. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China: Evidence from apatite fission track analysis

    Directory of Open Access Journals (Sweden)

    Wenhao Tang


    Full Text Available Apatite fission track (AFT analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0–13.2 μm mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassic–early Cretaceous and the Oligocene–Miocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma, recording the earlier rapid uplift phase during the late Jurassic–Cretaceous, while the ages in the north piedmont of the Bogda Mountain (namely the northeast part are younger (<60 Ma, mainly reflecting the later rapid uplift phase in the Oligocene–Miocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  7. Cenozoic uplift and exhumation in southern Sichuan Basin-Evidence from low-temperature thermochronology%四川盆地南部地区新生代隆升剥露研究——低温热年代学证据

    Institute of Scientific and Technical Information of China (English)

    邓宾; 刘树根; 王国芝; 李智武; 刘顺; 曹俊兴


    Abstract Based on the model of low-temperature thermochronology (apatite and zircon (U-Th)/He,apatite fission track) and folding in anticlines,we decipher the uplift and exhumation in southern Sichuan basin during Cenozoic time,which is characterized by low-relief and low-slope in topography.The Muchuan and Sangmuchang area underwent rapid uplift and exhumation in Oligocene-Miocene,with a rate of ~0.1 mm/a and a magnitude of 1.0~2.0 km of surface erosion.It indicates that the craton basement has exerted a significant influence on the regional uplift and exhumation.The apatite (U-Th)/He ages range from ~10 Ma to 28.6 Ma in Muchuananticline,there is a distinct decrease in AHe ages with the increasing depth to show a steady-state uplift and exhumation with a rate of 0.12-±-0.02 mm/a during this time.However,the apatite fission-track ages range from ~36 Ma to 52 Ma in Sangmuchang anticline,the AFT ages and the track lengths show no distinct change in depth,with a roughly similar value of ~50 Ma in ages and ~12.0 μtm in lengths.Temperature-time histories of AFT show that most samples experienced three episodes of evolution.After arriving at the largest depth of subsidence around ~80 Ma,there is a slow uplift and cooling process between 80 Ma to 20 Ma with a rate of ~0.025 mm/a,followed by a rapid uplift and exhumation with a rate of ~0.1 mm/a.The compression between the eastward moving crust in Tibet and the craton basement in Sichuan basin accommodated different kinematic vectors in vertical and horizontal under the control of different boundary faults around the basin.Thus,it had a profound influence on the mountbuilding in eastern margin of Tibetan plateau and Sichuan basin.%本文通过背斜褶皱变形与低温热年代学年龄(磷灰石和锆石(U-Th)/He、磷灰石裂变径迹)端元模型研究,约束低起伏度、低斜率地貌特征的四川盆地南部地区新生代隆升剥露过程.四川盆地南部沐川和桑木场背斜地区

  8. Rapid Prototyping Laboratory (United States)

    Federal Laboratory Consortium — The ARDEC Rapid Prototyping (RP) Laboratory was established in December 1992 to provide low cost RP capabilities to the ARDEC engineering community. The Stratasys,...

  9. 晚期折返过程含石墨流体包裹体及其意义:以印度两个不同地体为例%Graphite bearing fluid inclusions and their implications to late-stage exhumation processes: Case studies from two disparate terrains in India

    Institute of Scientific and Technical Information of China (English)

    M.K.Panigrahi; S.Gupta


    Archean greenstone belts and Proterozoic granulite mobile belts are products of fundamentally different tectonic processes that culminated in different levels of crustal incision. The present study focuses on graphite-bearing fluid inclusions from two such terrains in India, the Angul domain of Eastern Ghats Mobile Belt and Hutti-Maski schist belt of the eastern Dharwar greenstone-granite belt. In both cases, a high population of such inclusions within the fluid inclusion assemblage rules out the possibility of graphite being a captive phase, and instead confirms that it was deposited by the fluid within the inclusion cavity. Graphite is usually observed to be occurring with either pure water or a pure carbonic ( CO2 only) liquid, or with a CH4 dominated carbonic liquid without vapor at room temperature. Graphite precipitation in inclusions is brought about by reaction of the CO2 and CH4 trapped as a homogeneous fluid to give rise to H2O and C (graphite). Molar volume calculations for the CO2-CH4 mixture assuming an appropriate PVTX relationship indicates that there is a substantial increase in volume with decreasing pressure at a given temperature. The reaction producing graphite and H2O from CH4 and CO2 involves substantial volume reduction, and hence would be favored when the rock undergoes rapid exhumation. Graphite-bearing inclusions in quartz in a late-stage leucosome from migmatites in the Angul domain of the EGMB are accompanied by other fluid inclusion evidence for isothermal decompression. In the Hutti-Maski schist belt of the eastern Dharwar Craton, graphite-bearing inclusions occur in structurally controlled quartz veins (often auriferous ) within metamorphosed mafic volcanics (schists and amphibolites). The Raman spectra indicate that graphites in fluid inclusions from the Hutti-Maski schist belt have both ordered (O) and the disordered (D) peaks, whereas those from the Angul area of EGMB lack the disordered (D) peaks, process. However, the Hutti

  10. Metamorphic Tectonites and Differential Exhumation Reveal 3D Nature of Extension and Lower Crustal Flow in the Active Woodlark Rift, Papua New Guinea (United States)

    Little, T. A.; Baldwin, S. L.; Fitzgerald, P. G.; Monteleone, B. D.; Peters, K. J.


    The D'Entrecasteaux Islands metamorphic core complexes (MCCs) occur in the Woodlark rift, a continental region where ˜200 km of extension since ˜6 Ma has been focused into a relatively small number of normal faults, some dipping at 12 mm/yr. To the east, an MCC on eastern Normanby Island has top-north footwall mylonites that dip gently SW and that were exhumed during the Pliocene as part of a northward progression of normal faulting that did not arrive at the offshore Moresby Seamount until ˜1.2 Ma (ODP Leg 180 site), relationships that suggest a rolling-hinge style uplift. Importantly, its detachment exposes no rocks deeper than blueschist-facies. Ductile deformation fabrics in the MCCs reveal patterns of lower crustal motion that can be evaluated against seafloor spreading-derived plate motions. Shear fabrics in MCCs closest to the Woodlark spreading ridges, including Normanby and Misima Islands are parallel to the NNE direction of 0.5-3.6 Ma Solomon Sea-Australia spreading. Farther west, lineations in the lower plates of the D'Entrecasteaux MCCs locally deflect ˜40-50° clockwise from this direction. This obliquity is interpreted to reflect inhomogeneous lower crustal extension to the west of the Woodlark spreading ridges. A rift corridor extending ˜100 km to the north of Goodenough and Fergusson Islands is defined by active normal faulting and subsidence of the Trobriand margin. We infer that a previously subducted, locally eclogite-bearing, slab of thinned Australian lower crust to the north of the islands is being pulled out from beneath this zone as it is being sinistrally sheared along its eastern edge. Today the rift zone steps ˜70 km south towards the Papuan Peninsula to define a right-step, an asymmetry that is enhanced by seafloor spreading east of ˜151.4° E. Published focal mechanisms suggest that N-S sinistral shear along the northern Woodlark rift is continuing. In central Normanby Island, ˜2 Ma andesites may have erupted along a transverse

  11. Seismic evidence of exhumed mantle rock basement at the Gorringe Bank and the adjacent Horseshoe and Tagus abyssal plains (SW Iberia) (United States)

    Sallarès, Valentí; Martínez-Loriente, Sara; Prada, Manel; Gràcia, Eulàlia; Ranero, César; Gutscher, Marc-André; Bartolome, Rafael; Gailler, Audrey; Dañobeitia, Juan José; Zitellini, Nevio


    The Gorringe Bank is a gigantic seamount that separates the Horseshoe and Tagus abyssal plains offshore SW Iberia, in a zone that hosts the convergent boundary between the Africa and Eurasia plates. Although the region has been the focus of numerous investigations since the early 1970s, the lack of appropriate geophysical data makes the nature of the basement, and thus the origin of the structures, still debated. In this work, we present combined P-wave seismic velocity and gravity models along a transect that crosses the Gorringe Bank from the Tagus to the Horseshoe abyssal plains. The P-wave velocity structure of the basement is similar in the Tagus and Horseshoe plains. It shows a 2.5-3.0 km-thick top layer with a velocity gradient twice stronger than oceanic Layer 2 and an abrupt change to an underlying layer with a five-fold weaker gradient. Velocity and density is lower beneath the Gorringe Bank probably due to enhanced fracturing, that have led to rock disaggregation in the sediment-starved northern flank. In contrast to previous velocity models of this region, there is no evidence of a sharp crust-mantle boundary in any of the record sections. The modelling results indicate that the sediment overlays directly serpentinite rock, exhumed from the mantle with a degree of serpentinization decreasing from a maximum of 70-80% under the top of Gorringe Bank to less than 5% at a depth of ˜20 km. We propose that the three domains were originally part of a single serpentine rock band, of nature and possibly origin similar to the Iberia Abyssal Plain ocean-continent transition, which was probably generated during the earliest phase of the North Atlantic opening that followed continental crust breakup (Early Cretaceous). During the Miocene, the NW-SE trending Eurasia-Africa convergence resulted in thrusting of the southeastern segment of the exhumed serpentinite band over the northwestern one, forming the Gorringe Bank. The local deformation associated to plate

  12. Amphibolitization of eclogites in a subduction channel (Sistan belt, E. Iran): Monitoring changes in fluid composition during exhumation and tectonic implications (United States)

    Lorenz, Melanie; Angiboust, Samuel; Pourteau, Amaury; Omrani, Jafar


    Fluids released from subducting slabs are important for improving our understanding of mass transfer within subduction zones. Eclogites from the Sistan ophiolitic suture zone (eastern Iran) have a well preserved structure and a rather simple metamorphic history, making them an interesting target to monitor changing in fluid composition throughout their journey from eclogite-facies conditions towards the surface. The Sistan suture formed by the closure of a branch of the Neotethys during Cretaceous times. It comprises a stack of tectonic slices detached from various depths of this paleo-subduction complex. One of these slices is made of 10-meter sized blocks of eclogite wrapped by serpentinite schist (Angiboust et al., 2013). The eclogite assemblage (~550°C, 2.4 GPa), only visible in exposed block cores, has been strongly retrogressed by an amphibolite-facies paragenesis (~650°C, 1.2 GPa). The thermal overprint during exhumation has been ascribed to the juxtaposition of this unit to the overlying sub-continental serpentinized mantle. In the present study, one of the eclogitic blocks has been investigated for chemical changes associated with the amphibolitisation of the eclogite, in order to get an idea about the geochemical signature of retrograde fluids. Petrographic and geochemical observations point to high element mobility and multiple fluid-rock interaction events, visible in the sample as dissolution textures, mineral chemical oscillations and pervasive replacement by amphibolite-facies minerals. Whole-rock mass balance calculations and LA-ICP-MS measurements reveal at least two successive metasomatic events associated with the retrograde metamorphic overprint of the eclogitic block. Deep fluids (1.5-2.0 GPa) were apparently rather enriched in Mg, Cr, and Ni, indicating the presence of serpentinite-derived fluids, while later fluids associated with the climax of amphibolitization were clearly carriers of large ion lithophile elements (such as K, Ba, Sr

  13. Sedimentary response to orogenic exhumation in the northern rocky mountain basin and range province, flint creek basin, west-central Montana (United States)

    Portner, R.A.; Hendrix, M.S.; Stalker, J.C.; Miggins, D.P.; Sheriff, S.D.


    Middle Eocene through Upper Miocene sedimentary and volcanic rocks of the Flint Creek basin in western Montana accumulated during a period of significant paleoclimatic change and extension across the northern Rocky Mountain Basin and Range province. Gravity modelling, borehole data, and geologic mapping from the Flint Creek basin indicate that subsidence was focused along an extensionally reactivated Sevier thrust fault, which accommodated up to 800 m of basin fill while relaying stress between the dextral transtensional Lewis and Clark lineament to the north and the Anaconda core complex to the south. Northwesterly paleocurrent indicators, foliated metamorphic lithics, 64 Ma (40Ar/39Ar) muscovite grains, and 76 Ma (U-Pb) zircons in a ca. 27 Ma arkosic sandstone are consistent with Oligocene exhumation and erosion of the Anaconda core complex. The core complex and volcanic and magmatic rocks in its hangingwall created an important drainage divide during the Paleogene shedding detritus to the NNW and ESE. Following a major period of Early Miocene tectonism and erosion, regional drainage networks were reorganized such that paleoflow in the Flint Creek basin flowed east into an internally drained saline lake system. Renewed tectonism during Middle to Late Miocene time reestablished a west-directed drainage that is recorded by fluvial strata within a Late Miocene paleovalley. These tectonic reorganizations and associated drainage divide explain observed discrepancies in provenance studies across the province. Regional correlation of unconformities and lithofacies mapping in the Flint Creek basin suggest that localized tectonism and relative base level fluctuations controlled lithostratigraphic architecture.

  14. Contrast in stress-strain history during exhumation between high- and ultrahigh-pressure metamorphic units in the Western Alps: Microboudinage analysis of piemontite in metacherts (United States)

    Omori, Yasutomo; Barresi, Antonello; Kimura, Nozomi; Okamoto, Atsushi; Masuda, Toshiaki


    Our analyses of microboudinage structures of piemontite grains embedded within six samples of metachert, one collected from an ultrahigh-pressure (UHP) metamorphic unit at Lago di Cignana in Italy of the Western Alps, and the other five from surrounding high-pressure (HP) metamorphic units in Italy and France, have revealed that the structures are all symmetrical in type, and were presumably produced in coaxial strain fields. Stress-strain analyses of the microboudinaged grains revealed significant contrasts in the stress and strain histories of the UHP and HP metamorphic units, with the differential stress recorded by the UHP sample being unequivocally lower than that recorded by the five HP samples. In addition, our analyses showed that the UHP sample underwent stress-relaxation during microboudinage, whereas the five HP samples did not. On the basis of these observations and analyses we discuss the mechanical decoupling of the UHP and HP units that led to different histories in differential stress between the units during exhumation of the Western Alps.

  15. Rapid Airplane Parametric Input Design (RAPID) (United States)

    Smith, Robert E.


    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  16. Rapidly progressive Alzheimer disease. (United States)

    Schmidt, Christian; Wolff, Martin; Weitz, Michael; Bartlau, Thomas; Korth, Carsten; Zerr, Inga


    Different rates of progression have been observed among patients with Alzheimer disease. Risk factors that accelerate deterioration have been identified and some are being discussed, such as genetics, comorbidity, and the early appearance of Alzheimer disease motor signs. Progressive forms of Alzheimer disease have been reported with rapid cognitive decline and disease duration of only a few years. This short review aims to provide an overview of the current knowledge of rapidly progressive Alzheimer disease. Furthermore, we suggest that rapid, in this context, should be defined as a Mini-Mental State Examination score decrease of 6 points per year.

  17. Recrystallisation, phase mixing and strain localisation in peridotite during rapid extrusion of sub-arc mantle lithosphere (United States)

    Czertowicz, T. A.; Toy, V. G.; Scott, J. M.


    The Anita Peridotite, in southwestern New Zealand, is a ∼1 × 20 km ultramafic massif that was rapidly extruded from beneath a Cretaceous arc within the 4 km wide mylonitic Anita Shear Zone. The peridotitic body contains a spectacular array of textures that preserve evidence for changing temperature, stress, and deformation mechanisms during the exhumation process. Olivine and orthopyroxene microstructures and lattice-preferred orientations (LPO) record a three-phase deformation history. Dislocation glide on the C- and E-type slip systems is recorded by coarse pre-mylonitised olivine grains, and occurred under hydrous conditions at T ∼650 °C, stress ∼200-700 MPa and strain rate ∼10-15 s-1, probably within hydrated sub-arc mantle lithosphere. Rare protomylonite pods record deformation by dislocation creep in porphyroclasts and dislocation-accommodated grain boundary sliding in the matrix on {0kl}[100] in olivine and (100)[001] in orthopyroxene, under conditions of T ∼730-770 °C, stress ∼52-700 MPa and strain rate ∼10-15 s-1. The massif, however, is dominated by mylonite and ultramylonite that wrap the protomylonite pods, comprising mostly fine-grained olivine neoblasts that lack internal distortions and have uniform LPOs. These textures indicate deformation occurred by grain-size sensitive (GSS) creep at T ∼650 °C, stress ∼69-137 MPa and strain rate ∼10-15 s-1, and thus during conditions of cooling and decreasing stress. GSS creep became more dominant with time, as the proportion of randomly-oriented neoblasts increased and formed interlinked networks that accommodated much of the strain. Grain boundary pinning allowed GSS creep to be maintained in polyphase regions, following mixing of olivine and orthopyroxene, which may have occurred by grain boundary transport in a fluid phase during a "creep cavitation" process. The results indicate that the Anita Peridotite recrystallised and underwent rheological weakening at a constant strain rate

  18. SAP Sector Develops Rapidly

    Institute of Scientific and Technical Information of China (English)

    Zheng Chengwang


    @@ Stable demand growth internationally Super absorbent polymers (SAP) feature high water absorption, high water retention, rapid water absorption, great expanding power,strong thickening, strong anchoring and excellent elasticity.

  19. Rapid Lead Screening Test (United States)

    ... Vitro Diagnostics Tests Used In Clinical Care Rapid Lead Screening Test Share Tweet Linkedin Pin it More ... reducing the need for a follow-up visit. Lead Risk Links Centers for Disease Control and Prevention ( ...

  20. Hydropower RAPID Toolkit

    Energy Technology Data Exchange (ETDEWEB)


    This fact sheet provides a brief overview of the U.S. Department of Energy (DOE) Hydropower Regulatory and Permitting Information Desktop (RAPID) Toolkit including its capabilities, features, and benefits.

  1. Petrology of HP metamorphic veins in coesite-bearing eclogite from western Tianshan, China: Fluid processes and elemental mobility during exhumation in a cold subduction zone (United States)

    Lü, Zeng; Zhang, Lifei; Du, Jinxue; Yang, Xin; Tian, Zuolin; Xia, Bin


    A petrological study was carried out for high pressure (HP) veins which cut through the host coesite-bearing eclogites at Habutengsu-Kebuerte in western Tianshan, China. The results place constraints on the origin and property of metamorphic fluids during subduction-zone metamorphism. Omphacite-, clinozoisite- and quartz-dominated veins occur on centimeter to meter scales within lens-shaped and layered eclogites, or cutting into the country rocks of garnet phengite schists. Coesite-bearing eclogites mainly consist of fibrous fine-grained omphacite and porphyroblastic garnet, with minor amounts of amphibole (mainly barroisite), clinozoisite, white mica (mainly paragonite) and rutile. The veins are pronouncedly coarse-grained compared to the host eclogites and commonly consist of quartz, clinozosite, rutile, white mica (phengite and paragonite) and garnet, with or without omphacite, titanite, apatite, carbonate (mainly dolomite) and glaucophane. Fluid inclusions are abundant in vein omphacite, titanite and apatite, but are rare in the equivalent minerals of host eclogites. Rounded vein garnets usually occur close to the sharp interface of vein and host eclogite. Omphacite in the veins is characterized by its euhedral form surrounded by quartz, or coarse bladed aggregates in contrast to the fibrous or patchy one, suggesting dynamic recrystallization in the host rocks. Omphacite in both veins and host eclogites has similar jadeite contents (Jd40-50), indicating formation at eclogite-facies metamorphic conditions. Vein phengite uniformly contains certain amounts of Ba with maximum BaO content of 3.16-4.25 wt.%, suggesting that Ba was mobilized during the exhumation of UHP rocks. Specific textures of vein minerals, such as the enclosure of magnesite (or calcite) in dolomite, rutile in titanite, and the occurrence of zoned Ba-rich phengite, indicate the chemical variability of channelized fluids over time. Based on Zr content in rutile and the presence of paragonite

  2. Using apatite fission track thermochronology to document the deformation sequence in an exhumed foreland basin: an example from the southern Pyrenees. (United States)

    Meresse, F.; Labaume, P.; Jolivet, M.; Teixell, A.


    ) Results in the Hecho Group turbidites bring evidence of exhumation around 18 Ma on the Oturia thrust in the middle of the Jaca basin, an age that is younger than the Middle Eocene to Aquitanian deformation registered by tecto-sedimentary relationships in the southernmost part of the basin (Guarga syncline and SPFT). These tectonic movements may be related to the exhumation, at the same time, of the southern flank of the Axial Zone by out-of-sequence thrusting on the Bielsa basement thrust (Jolivet et al., 2007*). Therefore, low-temperature thermochronology reveals an out-of-sequence episode of deformation in the interior of the south-Pyrenean thrust wedge that had remained unknown due to the lack of related sedimentary record. This late tectonic activity is younger than the generally admitted Aquitanian age for the end of the Pyrenean compression, and would be linked to an ultimate internal thickening stage in the orogenic wedge (Meresse et al., this volume). (*Tectonics, 2007, vol. 26, doi: 10.1029/2006TC002080)

  3. Grain-scale Sr isotope heterogeneity in amphibolite (retrograded UHP eclogite, Dabie terrane): Implications for the origin and flow behavior of retrograde fluids during slab exhumation (United States)

    Guo, Shun; Yang, Yueheng; Chen, Yi; Su, Bin; Gao, Yijie; Zhang, Lingmin; Liu, Jingbo; Mao, Qian


    To constrain the origin and flow behavior of amphibolite-facies retrograde fluids during slab exhumation, we investigate the textures, trace element contents, and in situ strontium (Sr) isotopic compositions (using LA-MC-ICP-MS) of multiple types of epidote and apatite in the UHP eclogite and amphibolites from the Hualiangting area (Dabie terrane, China). The UHP epidote porphyroblasts in the eclogite (Ep-E), which formed at 28-30 kbar and 660-720 °C, contain high amounts of Sr, Pb, Th, Ba, and light rare earth elements (LREEs) and have a narrow range of initial 87Sr/86Sr ratios (0.70431 ± 0.00012 to 0.70454 ± 0.00010). Two types of amphibolite-facies epidote were recognized in the amphibolites. The first type of epidote (Ep-AI) developed in all the amphibolites and has slightly lower trace element contents than Ep-E. The Ep-AI has a same initial 87Sr/86Sr ratio range as the Ep-E and represents the primary amphibolite-facies retrograde product that is associated with an internally buffered fluid at 8.0-10.3 kbar and 646-674 °C. The other type of epidote (Ep-AII) occurs as irregular fragments, veins/veinlets, or reaction rims on the Ep-AI in certain amphibolites. Elemental X-ray maps reveal the presence of Ep-AI relics in the Ep-AII domains (appearing as a patchy texture), which indicates that Ep-AII most likely formed by the partial replacement of the Ep-AI in the presence of an infiltrating fluid. The distinctly lower trace element contents of Ep-AII are ascribed to element scavenging by a mechanism of dissolution-transport-precipitation during replacement. The Ep-AII in an individual amphibolite exhibits large intra- and inter-grain variations in the initial 87Sr/86Sr ratios (0.70493 ± 0.00030 to 0.70907 ± 0.00022), which are between those of the Ep-AI and granitic gneisses (wall rock of the amphibolites, 0.7097-0.7108). These results verify that the infiltrating fluid was externally derived from granitic gneisses. The matrix apatite in the amphibolites has

  4. Rapid middle Miocene extension and unroofing of the southern Ruby Mountains, Nevada (United States)

    Colgan, Joseph P.; Howard, Keith A.; Fleck, Robert J.; Wooden, Joseph L.


    Paleozoic rocks in the northern Ruby Mountains were metamorphosed during Mesozoic crustal shortening and Cenozoic magmatism, but equivalent strata in the southern Ruby Mountains were never buried deeper than stratigraphic depths prior to exhumation in the footwall of a west dipping brittle normal fault. In the southern Ruby Mountains, Miocene sedimentary rocks in the hanging wall of this fault date from 15.2 to 11.6 Ma and contain abundant detritus from the Paleozoic section. Apatite fission track and (U-Th)/He samples of the Eocene Harrison Pass pluton record rapid cooling that peaked ca. 17–15 Ma, while apatite fission track data from Jurassic plutons east and west of the southern Ruby Mountains indicate near-surface temperatures (pluton to be partially reset rather than to directly record fault slip. Our new data, together with published data on the distribution and composition of Miocene basin fill, suggest that rapid middle Miocene slip took place on the west dipping brittle detachment that bounds the Ruby Mountains and East Humboldt Range for 150 km along strike. This fault was thus active during a period of rapid extension (ca. 17–15 to 12–10 Ma) documented widely across the northern Basin and Range Province.

  5. Apatite fission-track evidence for regional exhumation in the subtropical Eocene, block faulting, and localized fluid flow in east-central Alaska (United States)

    Dusel-Bacon, Cynthia; Bacon, Charles R.; O'Sullivan, Paul B.; Day, Warren C.


    The origin and antiquity of the subdued topography of the Yukon–Tanana Upland (YTU), the physiographic province between the Denali and Tintina faults, are unresolved questions in the geologic history of interior Alaska and adjacent Yukon. We present apatite fission-track (AFT) results for 33 samples from the 2300 km2 western Fortymile district in the YTU in Alaska and propose an exhumation model that is consistent with preservation of volcanic rocks in valleys that requires base level stability of several drainages since latest Cretaceous–Paleocene time. AFT thermochronology indicates widespread cooling below ∼110 °C at ∼56–47 Ma (early Eocene) and ∼44–36 Ma (middle Eocene). Samples with ∼33–27, ∼19, and ∼10 Ma AFT ages, obtained near a major northeast-trending fault zone, apparently reflect hydrothermal fluid flow. Uplift and erosion following ∼107 Ma magmatism exposed plutonic rocks to different extents in various crustal blocks by latest Cretaceous time. We interpret the Eocene AFT ages to suggest that higher elevations were eroded during the Paleogene subtropical climate of the subarctic, while base level remained essentially stable. Tertiary basins outboard of the YTU contain sediment that may account for the required >2 km of removed overburden that was not carried to the sea by the ancestral Yukon River system. We consider a climate driven explanation for the Eocene AFT ages to be most consistent with geologic constraints in concert with block faulting related to translation on the Denali and Tintina faults resulting from oblique subduction along the southern margin of Alaska.

  6. Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains

    Directory of Open Access Journals (Sweden)

    Wilfried Bauer


    Full Text Available The metamorphic basement of the Heimefrontfjella in western Dronning Maud Land (Antarctica forms the western margin of the major ca. 500 million year old East African/East Antarctic Orogen that resulted from the collision of East Antarctica and greater India with the African cratons. The boundary between the tectonothermally overprinted part of the orogen and its north-western foreland is marked by the subvertical Heimefront Shear Zone. North-west of the Heimefront Shear Zone, numerous low-angle dipping ductile thrust zones cut through the Mesoproterozoic basement. Petrographic studies, optical quartz c-axis analyses and x-ray texture goniometry of quartz-rich mylonites were used to reveal the conditions that prevailed during the deformation. Mineral assemblages in thrust mylonites show that they were formed under greenschist-facies conditions. Quartz microstructures are characteristic of the subgrain rotation regime and oblique quartz lattice preferred orientations are typical of simple shear-dominated deformation. In contrast, in the Heimefront Shear Zone, quartz textures indicate mainly flattening strain with a minor dextral rotational component. These quartz microstructures and lattice preferred orientations show signs of post-tectonic annealing following the tectonic exhumation. The spatial relation between the sub-vertical Heimefront Shear Zone and the low-angle thrusts can be explained as being the result of strain partitioning during transpressive deformation. The pure-shear component with a weak dextral strike-slip was accommodated by the Heimefront Shear Zone, whereas the north–north-west directed thrusts accommodate the simple shear component with a tectonic transport towards the foreland of the orogen.

  7. From volcanic plains to glaciated peaks: Burial, uplift and exhumation history of southern East Greenland after opening of the NE Atlantic (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Nielsen, Troels F. D.; Chalmers, James A.


    In southern East Greenland (68-70°N), voluminous flood basalts erupted onto a largely horizontal lava plain near sea level at the Paleocene-Eocene transition when sea-floor spreading started in the NE Atlantic. Based on synthesis of geological observations, stratigraphic landform analysis and apatite fission-track analysis data in 90 rock samples, we show how three regional phases of uplift and exhumation subsequently shaped the present-day margin and controlled the discontinuous history of the Greenland ice sheet. A late Eocene phase of uplift led to formation of a regional erosion surface near sea level (the Upper Planation Surface, UPS). Uplift of the UPS in the late Miocene led to formation of the Lower Planation Surface (LPS) by incision below the uplifted UPS, and a Pliocene phase led to incision of valleys and fjords below the uplifted LPS, leaving mountain peaks reaching 3.7 km above sea level. Local uplift affected the Kangerlussuaq area (~ 68°N) during early Eocene emplacement of the Kangerlussuaq Intrusion and during late Oligocene block movements, that may be related to the detachment of the Jan Mayen microcontinent from Greenland, while middle Miocene thermal activity, coeval with lava eruptions, heated rocks along a prominent fault within the early Cretaceous to Paleocene Kangerlussuaq Basin. The three regional uplift phases are synchronous with phases in West Greenland, overlap in time with similar events in North America and Europe and also correlate with changes in plate motion. The much higher elevation of East Greenland compared to West Greenland suggests support in the east from the Iceland plume. These observations indicate a connection between mantle convection, changes in plate motion and vertical movements along passive continental margins.

  8. Rapid cooled lens cell (United States)

    Stubbs, David M.; Hsu, Ike C.


    This paper describes the optomechanical design, thermal analysis, fabrication, and test evaluation processes followed in developing a rapid cooled, infrared lens cell. Thermal analysis was the key engineering discipline exercised in the design phase. The effect of thermal stress on the lens, induced by rapid cooling of the lens cell, was investigated. Features of this lens cell that minimized the thermal stress will be discussed in a dedicated section. The results of thermal analysis on the selected lens cell design and the selection of the flow channel design in the heat exchanger will be discussed. Throughout the paper engineering drawings, illustrations, analytical results, and photographs of actual hardware are presented.

  9. Rapid microbiology - raising awareness. (United States)

    Bailie, Jonathan


    A 'high-level overview' of some of the emerging rapid microbiology technologies designed to help healthcare engineering and infection control teams working in hospitals and other healthcare facilities more rapidly identify potentially hazardous levels of waterborne microorganisms in their water systems, enabling them to take prompt remedial action, and a look at the some of the 'pros and cons' of such testing techniques, was given by Nalco technical director, Howard Barnes, the vice-chair of the Legionella Control Association (LCA), at a recent LCA open day. HEJ editor, Jonathan Bailie, reports.

  10. Rapid-Sequence Intubation

    Directory of Open Access Journals (Sweden)

    Evangelina Dávila Cabo de Villa


    Full Text Available In medical practice there are several situations that require immediate intervention of the airway in some patients, in order to ensure proper entrance and exit of gases into and out of the lungs and prevent aspiration. Rapid-sequence intubation has been considered as the administration of a hypnotic agent and a neuromuscular relaxant consecutively (virtually simultaneously to facilitate orotracheal intubation in critically ill patients and minimize the risk of aspiration. This paper aims to collect elements that promote a successful medical management according to the situation presented, since there is no single way of proceeding in case of rapid-sequence intubation. The elements to consider include: knowing the anatomy of the upper respiratory tract, having a group of drugs to choose from, receiving adequate training and having an alternative plan for the difficulties that may arise.

  11. Rapid Detection of Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    David Perlin


    Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development

  12. New Rapid Spore Assay (United States)

    Kminek, Gerhard; Conley, Catharine


    The presentation will detail approved Planetary Protection specifications for the Rapid Spore Assay for spacecraft components and subsystems. Outlined will be the research and studies on which the specifications were based. The research, funded by ESA and NASA/JPL, was conducted over a period of two years and was followed by limited cleanroom studies to assess the feasibility of this assay during spacecraft assembly.

  13. Tiber Personal Rapid Transit

    Directory of Open Access Journals (Sweden)

    Diego Carlo D'agostino


    Full Text Available The project “Tiber Personal Rapid Transit” have been presented by the author at the Rome City Vision Competition1 2010, an ideas competition, which challenges architects, engineers, designers, students and creatives individuals to develop visionary urban proposals with the intention of stimulating and supporting the contemporary city, in this case Rome. The Tiber PRT proposal tries to answer the competition questions with the definition of a provocative idea: a Personal Rapid transit System on the Tiber river banks. The project is located in the central section of the Tiber river and aims at the renewal of the river banks with the insertion of a Personal Rapid Transit infrastructure. The project area include the riverbank of Tiber from Rome Transtevere RFI station to Piazza del Popolo, an area where main touristic and leisure attractions are located. The intervention area is actually no used by the city users and residents and constitute itself a strong barrier in the heart of the historic city.

  14. Two-stage fluid flow and element transfers in shear zones during collision burial-exhumation cycle: Insights from the Mont Blanc Crystalline Massif (Western Alps) (United States)

    Rolland, Y.; Rossi, M.


    The Mont-Blanc Massif was intensely deformed during the Alpine orogenesis: in a first stage of prograde underthrusting at c. 30 Ma and in a second stage of uplift and exhumation at 22-11 Ma. Mid-crustal shear zones of 1 mm-50 m size, neighbouring episyenites (quartz-dissolved altered granite) and alpine veins, have localised intense fluid flow, which produced substantial changes in mineralogy and whole-rock geochemistry. Four main metamorphic zones are oriented parallel to the strike of the massif: (i) epidote, (ii) chlorite, (iii) actinolite-muscovite ± biotite and (iv) muscovite ± biotite. In addition, phlogopite-bearing shear zones occur in the chlorite zone, and calcite-bearing shear zones are locally found in the muscovite zone. The initial chemical composition of the granitic protolith is relatively constant at massif scale, which allows investigating compositional changes related to shear zone activity, and subsequent volume change and elements mobility. The variations of whole-rock composition and mineral chemistry in shear zones reflect variations in fluid/rock ratios and fluid's chemistry, which have produced specific mineral reactions. Estimated time-integrated fluid fluxes are of the order of 106 m3/m2. The mineral assemblages that crystallised upon these fluid-P-T conditions are responsible for specific major and trace element enrichments. The XFe (Fe/Fe + Mg) pattern of shear zone phyllosilicates and the δ13C pattern of vein calcite both show a bell-type pattern across the massif with high values on the massif rims and low values in the centre of the massif. These low XFe and δ13C values are explained by down temperature up-flow of a Fe-Mg-CO2-rich and silica-depleted fluid during stage 1, while the massif was underthrusting. These produced phlogopite, chlorite and actinolite precipitation and quartz hydrolysis, resulting in strong volume losses. In contrast, during stage 2 (uplift), substantial volume gains occurred on the massif rims due to the

  15. Field and Microstructure Study of Transpressive Jogdadi shear zone near Ambaji, Aravalli- Delhi Mobile Belt, NW India and its tectonic implication on the exhumation of granulites. (United States)

    Tiwari, Sudheer Kumar; Biswal, Tapas Kumar


    reduces in proportion and size. S fabric makes 13°- 40° angle with C-plane. From shear fabric NW oblique vergence has been interpreted. The Rigid Grain Net analysis of porphyroclast suggests mean kinematic vorticity number (Wm) range from 0.40 to 0.82. It suggests that this is transpressive shear zone. The mineral assemblages namely Qtz+ K- Flds+ Grt+ Bt in granite and Pla+ Hbl+ Bt in basic granulites suggests amphibolite facies of metamorphism during mylonitisation. Thus the exhumation of granulites is primarily accomplished through several parallel thrusts with Jogdadi shear zone which are transpressive in nature. Subsequently extensional condition and normal faulting have removed the cover rocks.

  16. Right-Rapid-Rough (United States)

    Lawrence, Craig


    IDEO (pronounced 'eye-dee-oh') is an international design, engineering, and innovation firm that has developed thousands of products and services for clients across a wide range of industries. Its process and culture attracted the attention of academics, businesses, and journalists around the world, and are the subject of a bestselling book, The Art of Innovation by Tom Kelley. One of the keys to IDEO's success is its use of prototyping as a tool for rapid innovation. This story covers some of IDEO's projects, and gives reasons for why they were successful.

  17. Rapid prototype and test

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, D.L.; Hansche, B.D.


    In order to support advanced manufacturing, Sandia has acquired the capability to produce plastic prototypes using stereolithography. Currently, these prototypes are used mainly to verify part geometry and ``fit and form`` checks. This project investigates methods for rapidly testing these plastic prototypes, and inferring from prototype test data actual metal part performance and behavior. Performances examined include static load/stress response, and structural dynamic (modal) and vibration behavior. The integration of advanced non-contacting measurement techniques including scanning laser velocimetry, laser holography, and thermoelasticity into testing of these prototypes is described. Photoelastic properties of the epoxy prototypes to reveal full field stress/strain fields are also explored.

  18. Rapidly progressive tabetic neurosyphilis

    Institute of Scientific and Technical Information of China (English)

    赖伟红; 薛华忠; 韩国柱


    Since the sexually transmitted diseases were recognized as a public health problem in China during the early 1980's, the incidence of syphilis has gradually increased. Though there have been case reports of clinical variants of neurosyphilis, including syphilitic cerebrospinal meningitis or meningomyelitis and meningovascular syphilis, occurring in different regions of China,1-3 tabes dorsalis or tabetic neurosyphilis has not yet been reported in China. Here, we report a young man with rapidly progressive tabetic neurosyphilis admitted to our hospital in October 1999.

  19. FFAGS for rapid acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Carol J. Johnstone and Shane Koscielniak


    When large transverse and longitudinal emittances are to be transported through a circular machine, extremely rapid acceleration holds the advantage that the beam becomes immune to nonlinear resonances because there is insufficient time for amplitudes to build up. Uncooled muon beams exhibit large emittances and require fast acceleration to avoid decay losses and would benefit from this style of acceleration. The approach here employs a fixed-field alternating gradient or FFAG magnet structure and a fixed frequency acceleration system. Acceptance is enhanced by the use only of linear lattice elements, and fixed-frequency rf enables the use of cavities with large shunt resistance and quality factor.


    Institute of Scientific and Technical Information of China (English)


    Povas esti tre malpla■e en urbegoj, se estas du lokoj, kie flugma■ino povas alteri■i, kaj oni devas rapi-de transiri de unu al la alia. Tiel estas ekzemple en Parizo. Foje mi alteri■is en Charles-de-Gaulle[elparolu■arl de gol’], kaj devis reekflugi el Orly[orli’]. Mi havis malmulte da tempo inter la alveno en unu kaj laflugo el la alia. Kaj jen la personaro, kiu funkciigas la publikajn transportojn, tiutage ne ofieis, ■ar la ■tatomalkonsentis altigi ■ian laborpagon. La urbo estis tiom plena je veturiloj, ke estis preskaǔneeble

  1. The Rapid Transient Surveyor

    CERN Document Server

    Baranec, Christoph; Wright, Shelley A; Tonry, John; Tully, R Brent; Szapudi, István; Takamiya, Marianne; Hunter, Lisa; Riddle, Reed; Chen, Shaojie; Chun, Mark


    The Rapid Transient Surveyor (RTS) is a proposed rapid-response, high-cadence adaptive optics (AO) facility for the UH 2.2-m telescope on Maunakea. RTS will uniquely address the need for high-acuity and sensitive near-infrared spectral follow-up observations of tens of thousands of objects in mere months by combining an excellent observing site, unmatched robotic observational efficiency, and an AO system that significantly increases both sensitivity and spatial resolving power. We will initially use RTS to obtain the infrared spectra of ~4,000 Type Ia supernovae identified by the Asteroid Terrestrial-Impact Last Alert System over a two year period that will be crucial to precisely measuring distances and mapping the distribution of dark matter in the z < 0.1 universe. RTS will comprise an upgraded version of the Robo-AO laser AO system and will respond quickly to target-of-opportunity events, minimizing the time between discovery and characterization. RTS will acquire simultaneous-multicolor images with a...

  2. The rapid transient surveyor (United States)

    Baranec, C.; Lu, J. R.; Wright, S. A.; Tonry, J.; Tully, R. B.; Szapudi, I.; Takamiya, M.; Hunter, L.; Riddle, R.; Chen, S.; Chun, M.


    The Rapid Transient Surveyor (RTS) is a proposed rapid-response, high-cadence adaptive optics (AO) facility for the UH 2.2-m telescope on Maunakea. RTS will uniquely address the need for high-acuity and sensitive near-infrared spectral follow-up observations of tens of thousands of objects in mere months by combining an excellent observing site, unmatched robotic observational efficiency, and an AO system that significantly increases both sensitivity and spatial resolving power. We will initially use RTS to obtain the infrared spectra of 4,000 Type Ia supernovae identified by the Asteroid Terrestrial-Impact Last Alert System over a two year period that will be crucial to precisely measuring distances and mapping the distribution of dark matter in the z efficiency prism integral field unit spectrograph: R = 70-140 over a total bandpass of 840-1830nm with an 8.7" by 6.0" field of view (0.15" spaxels). The AO correction boosts the infrared point-source sensitivity of the spectrograph against the sky background by a factor of seven for faint targets, giving the UH 2.2-m the H-band sensitivity of a 5.7-m telescope without AO.

  3. Rapid chemical separations

    CERN Document Server

    Trautmann, N


    A survey is given on the progress of fast chemical separation procedures during the last few years. Fast, discontinuous separation techniques are illustrated by a procedure for niobium. The use of such techniques for the chemical characterization of the heaviest known elements is described. Other rapid separation methods from aqueous solutions are summarized. The application of the high speed liquid chromatography to the separation of chemically similar elements is outlined. The use of the gas jet recoil transport method for nuclear reaction products and its combination with a continuous solvent extraction technique and with a thermochromatographic separation is presented. Different separation methods in the gas phase are briefly discussed and the attachment of a thermochromatographic technique to an on-line mass separator is shown. (45 refs).

  4. Rapid Diagnosis of Malaria

    Directory of Open Access Journals (Sweden)

    Clinton K. Murray


    Full Text Available Malaria's global impact is expansive and includes the extremes of the healthcare system ranging from international travelers returning to nonendemic regions with tertiary referral medical care to residents in hyperendemic regions without access to medical care. Implementation of prompt and accurate diagnosis is needed to curb the expanding global impact of malaria associated with ever-increasing antimalarial drug resistance. Traditionally, malaria is diagnosed using clinical criteria and/or light microscopy even though both strategies are clearly inadequate in many healthcare settings. Hand held immunochromatographic rapid diagnostic tests (RDTs have been recognized as an ideal alternative method for diagnosing malaria. Numerous malaria RDTs have been developed and are widely available; however, an assortment of issues related to these products have become apparent. This review provides a summary of RDT including effectiveness and strategies to select the ideal RDT in varying healthcare settings.

  5. Rapid automated nuclear chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, R.A.


    Rapid Automated Nuclear Chemistry (RANC) can be thought of as the Z-separation of Neutron-rich Isotopes by Automated Methods. The range of RANC studies of fission and its products is large. In a sense, the studies can be categorized into various energy ranges from the highest where the fission process and particle emission are considered, to low energies where nuclear dynamics are being explored. This paper presents a table which gives examples of current research using RANC on fission and fission products. The remainder of this text is divided into three parts. The first contains a discussion of the chemical methods available for the fission product elements, the second describes the major techniques, and in the last section, examples of recent results are discussed as illustrations of the use of RANC.

  6. Rapid Refresh (RAP) [20 km (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental...

  7. Rapid Refresh (RAP) [13 km (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental...

  8. The Rapid Transient Surveyor (United States)

    Baranec, Christoph; Tonry, John; Wright, Shelley; Tully, R. Brent; Lu, Jessica R.; Takamiya, Marianne Y.; Hunter, Lisa


    The next decade of astronomy will be dominated by large area surveys (see the detailed discussion in the Astro-2010 Decadal survey and NRC's recent OIR System Report). Ground-based optical transient surveys, e.g., LSST, ZTF and ATLAS and space-based exoplanet, supernova, and lensing surveys such as TESS and WFIRST will join the Gaia all-sky astrometric survey in producing a flood of data that will enable leaps in our understanding of the universe. There is a critical need for further characterization of these discoveries through high angular resolution images, deeper images, spectra, or observations at different cadences or periods than the main surveys. Such follow-up characterization must be well matched to the particular surveys, and requires sufficient additional observing resources and time to cover the extensive number of targets.We describe plans for the Rapid Transient Surveyor (RTS), a permanently mounted, rapid-response, high-cadence facility for follow-up characterization of transient objects on the U. of Hawai'i 2.2-m telescope on Maunakea. RTS will comprise an improved robotic laser adaptive optics system, based on the prototype Robo-AO system (formerly at the Palomar 1.5-m and now at the Kitt Peak 2.2-m telescope), with simultaneous visible and near-infrared imagers as well as a near-infrared integral field spectrograph (R~100, λ = 850 - 1830 nm, 0.15″ spaxels, 8.7″×6.0″ FoV). RTS will achieve an acuity of ~0.07″ in visible wavelengths and automated detection and characterization of astrophysical transients during a sustained observing campaign will yield the necessary statistics to precisely map dark matter in the local universe.

  9. Rapid geophysical surveyor

    Energy Technology Data Exchange (ETDEWEB)

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.


    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved.

  10. Rapid geophysical surveyor

    Energy Technology Data Exchange (ETDEWEB)

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.


    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved.

  11. Building a rapid response team. (United States)

    Halvorsen, Lisa; Garolis, Salomeja; Wallace-Scroggs, Allyson; Stenstrom, Judy; Maunder, Richard


    The use of rapid response teams is a relatively new approach for decreasing or eliminating codes in acute care hospitals. Based on the principles of a code team for cardiac and/or respiratory arrest in non-critical care units, the rapid response teams have specially trained nursing, respiratory, and medical personnel to respond to calls from general care units to assess and manage decompensating or rapidly changing patients before their conditions escalate to a full code situation. This article describes the processes used to develop a rapid response team, clinical indicators for triggering a rapid response team call, topics addressed in an educational program for the rapid response team members, and methods for evaluating effectiveness of the rapid response team.

  12. Syn-collapse eclogite metamorphism and exhumation of deep crust in a migmatite dome: The P-T-t record of the youngest Variscan eclogite (Montagne Noire, French Massif Central) (United States)

    Whitney, Donna L.; Roger, Françoise; Teyssier, Christian; Rey, Patrice F.; Respaut, J.-P.


    In many orogens, high-pressure (HP) metamorphic rocks such as eclogite occur as lenses in quartzofeldspathic gneiss that equilibrated at much lower pressures. The pressure-temperature-time (P-T-t) history of eclogite relative to host gneiss provides information about mechanisms and timescales of exhumation of orogenic crust. The Montagne Noire of the southern Massif Central, France, is an eclogite-bearing gneiss (migmatite) dome located at the orogen-foreland transition of the Variscan belt. Results of our study show that it contains the youngest eclogite in the orogen, similar in age to migmatite and granite that crystallized under low-pressure conditions. P-T conditions for an exceptionally unaltered eclogite from the central Montagne Noire were estimated using a pseudosection supplemented by garnet-clinopyroxene and Zr-in-rutile thermometry. Results indicate peak P ∼ 1.4 GPa and T ∼ 725°C for Mg-rich garnet rim (50 mol% pyrope) + omphacite (36 mol% jadeite) + rutile + quartz. U-Pb geochronology (LA-ICP-MS) of 16 zoned zircon grains yielded ∼360 Ma (4 cores) and ∼315 Ma (12 rims and cores). Rare earth element abundances determined by LA-ICP-MS for dated zircon are consistent with crystallization of ∼315 Ma zircon under garnet-stable, plagioclase-unstable conditions that we interpret to indicate high pressure; in contrast, the ∼360 Ma zircon core corresponds to crystallization under lower pressure plagioclase-stable conditions. Based on garnet zoning and inclusion suites, rutile textures and Zr zoning, P-T results, and zircon petrochronology, we interpret the ∼315 Ma date as the age of eclogite-facies metamorphism that only slightly preceded dome formation and crystallization at 315-300 Ma. This age relation indicates that eclogite formation at high pressure and migmatite dome emplacement at low pressure were closely spaced in time. We propose that collapse-driven material transfer from the hot orogen to the cool foreland resulted in thickening of

  13. Rapidly rotating red giants

    CERN Document Server

    Gehan, Charlotte; Michel, Eric


    Stellar oscillations give seismic information on the internal properties of stars. Red giants are targets of interest since they present mixed modes, which behave as pressure modes in the convective envelope and as gravity modes in the radiative core. Mixed modes thus directly probe red giant cores, and allow in particular the study of their mean core rotation. The high-quality data obtained by CoRoT and Kepler satellites represent an unprecedented perspective to obtain thousands of measurements of red giant core rotation, in order to improve our understanding of stellar physics in deep stellar interiors. We developed an automated method to obtain such core rotation measurements and validated it for stars on the red giant branch. In this work, we particularly focus on the specific application of this method to red giants having a rapid core rotation. They show complex spectra where it is tricky to disentangle rotational splittings from mixed-mode period spacings. We demonstrate that the method based on the id...

  14. Rapid Polymer Sequencer (United States)

    Stolc, Viktor (Inventor); Brock, Matthew W (Inventor)


    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal direction, or in a transverse direction, in the tip region, a polymer sequence is passed through the tip region, and a change in an electrical current signal is measured as each polymer component passes through the tip region. Each of the measured changes in electrical current signals is compared with a database of reference electrical change signals, with each reference signal corresponding to an identified polymer component, to identify the unknown polymer component with a reference polymer component. The nanopore preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  15. Rapidly Evolving Giant Dermatofibroma

    Directory of Open Access Journals (Sweden)

    K. J. Lang


    Full Text Available Dermatofibroma, also known as “fibrous histiocytoma”, is a benign dermal or subcutaneous poorly circumscribed proliferation of spindle-shaped fibroblasts and macrophages in the dermis. Although it is commonly present as a brownish nodule the legs of females, it may also arise on the upper extremities, trunk, and rarely on the head. The exact pathogenesis is unclear. However, it is widely believed that the originating insult to the dermis is a folliculitis, an arthropod bite, or an unspecified initial inflammatory condition. Giant dermatofibromas of greater than 5 cm in diameter are rare, with only 22 cases reported in the literature. We present a case of a rapidly evolving pedunculated mass in the groin of a male patient. Histological examination confirmed this to be a giant dermatofibroma. Though this specimen cannot is not confirmed as such, the cellular subtype is sometimes present as a larger lesion with anecdotal reports of local recurrence and distant metastases. The clinical and radiological features which were somewhat suspicious of malignancy are considered in the context of the definitive pathological diagnosis of a benign lesion.

  16. Procedimentos em exumações para investigação de vínculo genético em ossos Exhumations procedures for investigating the genetic link in bones

    Directory of Open Access Journals (Sweden)

    João Arnaldo Damião Melki


    Full Text Available OBJETIVO: Identificar problemas técnicos nas exumações para pesquisa de DNA em ossos e propor soluções por meio de protocolo. MÉTODOS: Estudo prospectivo e qualitativo das exumações, procedendo cada etapa da perícia conforme proposto na literatura médico-legal. Foram realizadas dez exumações no período de 1995 a 1998, para coleta de restos humanos e extração do DNA, sendo sete de interesse civil e três, criminal. As dificuldades técnicas surgidas na execução desses procedimentos foram resolvidas a partir de alternativas estabelecidas. RESULTADOS: A escassez de informações úteis para a identificação do indivíduo, baseada em seus restos mortais, foi observada em todos os casos. As características morfológicas individuais contribuíram para a identificação em 50% dos casos. O auxílio dos familiares foi importante na revelação dessas características. Em três casos, foi indicado apenas o sexo e, em um, a idade. A falta de infra-estrutura dos cemitérios e de segurança policial dificultou o trabalho pericial. CONCLUSÕES: Para garantir a fidelidade do exame molecular do DNA é necessário identificar de quem são os restos mortais a serem exumados. Para a eficiência da perícia, é fundamental o uso de um protocolo que inclua, entre outras questões, as relativas a identificação, infra-estrutura e segurança pessoal dos peritos no local do exame.OBJECTIVE: To identify technical problems in exhumations performed for DNA detection in bones and to propose solutions through a protocol. METHODS: A prospective and qualitative study of exhumations was carried out according to the methods proposed in the medical legal literature. From 1995 to 1998, were performed 10 exhumations to collect human remains for DNA extraction. Of them, seven cases were of civil interest and three of criminal. Alternatives were sought to overcome technical difficulties found during the execution of these procedures. RESULTS: For all cases

  17. Rapid Robot Design Validation Project (United States)

    National Aeronautics and Space Administration — Energid Technologies will create a comprehensive software infrastructure for rapid validation of robot designs. The software will support push-button validation...

  18. Rapid Robot Design Validation Project (United States)

    National Aeronautics and Space Administration — Energid Technologies will create a comprehensive software infrastructure for rapid validation of robotic designs. The software will support push-button validation...

  19. In-Space Rapid Manufacturing (United States)

    Cooper, Kenneth G.


    In-space manufacturing objectives are: (1) Develop and demonstrate capability to directly fabricate components in space using rapid prototyping technology - ceramics (alumina, silicon nitride, zirconia), metallics (stainless, inconel, etc.), high strength/temperature plastics (PEEK). and ABS plastics (starting point). (2) Perform material science experiments on rapid prototyping candidate materials in microgravity.

  20. Dimethyl Ether Sector Develops Rapidly

    Institute of Scientific and Technical Information of China (English)

    Zong Yangong


    @@ Rapid capacity expansion Dimethyl ether production in China has developed rapidly in recent years. The total capacity of dimethyl ether in China was only 31.8 thousand t/a in 2002, the output was around 20 thousand tons and the operating rate was 63%. The number of producers increased to over 30 in 2006.

  1. How Rapid is Rapid Prototyping? Analysis of ESPADON Programme Results

    Directory of Open Access Journals (Sweden)

    Ian D. Alston


    Full Text Available New methodologies, engineering processes, and support environments are beginning to emerge for embedded signal processing systems. The main objectives are to enable defence industry to field state-of-the-art products in less time and with lower costs, including retrofits and upgrades, based predominately on commercial off the shelf (COTS components and the model-year concept. One of the cornerstones of the new methodologies is the concept of rapid prototyping. This is the ability to rapidly and seamlessly move from functional design to the architectural design to the implementation, through automatic code generation tools, onto real-time COTS test beds. In this paper, we try to quantify the term “rapid” and provide results, the metrics, from two independent benchmarks, a radar and sonar beamforming application subset. The metrics show that the rapid prototyping process may be sixteen times faster than a conventional process.

  2. A Rapid Coliform Detector Project (United States)

    National Aeronautics and Space Administration — ORBITEC, in collaboration with Lucigen, proposes a rapid genetic detector for spaceflight water systems to enable real-time detection of E-coli with minimal...

  3. Rapid Multiplex Microbial Detector Project (United States)

    National Aeronautics and Space Administration — ORBITEC, in collaboration with Lucigen, proposes a rapid nucleic acid-based detector for spaceflight water systems to enable simultaneous quantification of multiple...

  4. Rapidity correlations test stochastic hydrodynamics

    CERN Document Server

    Zin, Christopher; Moschelli, George


    We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time $\\tau_{\\pi}$ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity $\

  5. Automated Tools for Rapid Prototyping

    Institute of Scientific and Technical Information of China (English)



    An automated environment is presented which aids the software engineers in developing data processing systems by using rapid prototyping techniques.The environment is being developed on VAX station.It can render good support to the specification of the requirements and the rapid creation of prototype.The goal,the methodology,the general structure of the environment and two sub-systems are discussed.

  6. Trans-Amazonian U-Th-Pb monazite ages and P-T-d exhumation paths of garnet-bearing leucogranite and migmatitic country rock of the southeastern Tandilia belt, Rio de la Plata craton in Argentina (United States)

    Martínez, Juan Cruz; Massonne, Hans-Joachim; Frisicale, María Cristina; Dristas, Jorge A.


    A garnet-bearing leucogranite and two country rocks from the Transamazonian Tandilia belt of the Rio de la Plata craton were studied in detail. The leucogranite contains garnet with homogeneous composition of pyr6(gros + andr)2spes5alm87. In a garnet-biotite migmatite, the core and rim compositions of garnet are pyr1.7(gros + andr)5spes5.6alm87.7 and pyr1.2(gros + andr)5.5spes6.7alm86.6, respectively. These compositions in a sillimanite-garnet-muscovite migmatite are pyr4(gros + andr)2.7spes2.7alm90.6 and pyr2.7(gros + andr)4spes3.2alm90.1, respectively. We used this information to decipher the P-T evolution of the rocks applying P-T and T-H2O pseudosections with the PERPLE_X computer software package taking into consideration deformational microstructures. The leucogranite records an isothermal decompression from 5.3 to 3.8 kbar at 665 °C. The garnet-biotite migmatite was exhumed from 5.5 kbar at 630 °C to 4.3 kbar at 615 °C and the sillimanite-garnet-muscovite migmatite from supersolidus conditions of 670 °C and 3.6 kbar to 625 °C at 2.4 kbar. Late andalusite formed in this rock. Seventy four analyses of 28 monazite grains of the country rocks yielded three groups of U-Th-Pb ages which were related to a collisional event (I: ca. 2.13-2.14 Ga.), a postcollisional thermal overprint (II: ca. 2.01 Ga) and slow cooling of the orogen (III: 1.80-1.90 Ga). Inherited ages of 2.28 and 2.25 Ga could refer to an early accretionary stage of the orogen. An age of 2.41 Ga indicates the presence of recycled Siderian continental crust. Synkinematic crystallization of melts and the subsolidus development of an S2-foliation, demonstrated by deformational microstructures, occurred during the exhumation of the studied area from depths of 18 km to 8 km in the time interval 2.01-1.90 Ga.

  7. Neogene shortening and exhumation of the Zagros fold-thrust belt and foreland basin in the Kurdistan region of northern Iraq (United States)

    Koshnaw, Renas I.; Horton, Brian K.; Stockli, Daniel F.; Barber, Douglas E.; Tamar-Agha, Mazin Y.; Kendall, Jerome J.


    The Zagros fold-thrust belt in the Kurdistan region of Iraq encroached southward toward a rapidly subsiding Neogene foreland basin and was later partitioned by out-of-sequence shortening focused along the Mountain Front Flexure (MFF), as defined by new low-temperature thermochronologic, stratigraphic, and provenance results. Apatite (U-Th)/He ages document rapid deformation advance from the Main Zagros Fault to southern frontal structures (Kirkuk, Shakal, and Qamar thrusts) at 10-8 Ma, followed by potential basement-involved out-of-sequence development of the MFF (Qaradagh anticline) by 5 Ma. Distinct shifts in detrital zircon U-Pb provenance signatures for Neogene foreland basin fill provide evidence for drainage reorganization during fold-thrust belt advance. U-Pb age spectra and petrologic data from the Injana (Upper Fars) Formation indicate derivation from a variety of Eurasian, Pan-African, ophiolitic and Mesozoic-Cenozoic volcanic terranes, whereas the Mukdadiya (Lower Bakhtiari) and Bai-Hasan (Upper Bakhtiari) Formations show nearly exclusive derivation from the Paleogene Walash-Naopurdan volcanic complex near the Iraq-Iran border. Such a sharp cutoff in Eurasian, Pan-African, and ophiolitic sources is likely associated with drainage reorganization and tectonic development of the geomorphic barrier formed by the MFF. As a result of Zagros crustal shortening, thickening and loading, the Neogene foreland basin developed and accommodated an abrupt influx of fluvial clastic sediment that contains growth stratal evidence of synkinematic accumulation. The apparent out-of-sequence pattern of upper crustal shortening in the hinterland to foreland zone of Iraqi Kurdistan suggests that structural inheritance and the effects of synorogenic erosion and accumulation are important factors influencing the irregular and episodic nature of orogenic growth in the Zagros.

  8. Biomass Rapid Analysis Network (BRAN)

    Energy Technology Data Exchange (ETDEWEB)


    Helping the emerging biotechnology industry develop new tools and methods for real-time analysis of biomass feedstocks, process intermediates and The Biomass Rapid Analysis Network is designed to fast track the development of modern tools and methods for biomass analysis to accelerate the development of the emerging industry. The network will be led by industry and organized and coordinated through the National Renewable Energy Lab. The network will provide training and other activities of interest to BRAN members. BRAN members will share the cost and work of rapid analysis method development, validate the new methods, and work together to develop the training for the future biomass conversion workforce.

  9. U/Pb ages on detrital zircons in the southern central Andes Neogene foreland (36°-37°S): Constraints on Andean exhumation (United States)

    Sagripanti, Lucía; Bottesi, Germán; Naipauer, Maximiliano; Folguera, Andrés; Ramos, Victor A.


    U/Pb dating on detrital zircons was performed in the Pampa de Carrizalito depocenter of the Late Miocene foreland basin associated with the Southern Central Andes orogenic front. This reveals Andean and pre-Andean components in magmatic derived zircons inhomogeneously distributed through the sequence. Andean, Grenville, Pampean, Famatinian and Gondwanic components reveal a complex source distribution from either the Main Andes, Coastal Cordillera and basement foreland areas. These are discussed showing different patterns in the context of the Andean orogenic cycle. Cretaceous and Jurassic components that are partly related to Mesozoic batholiths, developed at the western slope of the Andes at these latitudes, have a very contrasting behavior through the sequence: While Jurassic grains are represented from base to top, Cretaceous ones dilute upwardly. This is explained through the progressive uplift of the Southern Central Andes that could have created a barrier to Cretaceous and Jurassic detritus, while the older ones could have had either an alternative source area represented by the inverted rift system of the Huincul Ridge in the foreland area and the Cordillera del Viento in the hinterland area or the reworking of Jurassic sedimentary sequences of the Neuquén basin. Finally, a progressive enrichment in pre-Andean components to the top of the sequence is interpreted as related to the development of a broken foreland and the consequent rapid expansion of the orogenic front at the time of development of a slab shallowing setting in the region as shown by previous works.

  10. Rapid thermal processing of semiconductors

    CERN Document Server

    Borisenko, Victor E


    Rapid thermal processing has contributed to the development of single wafer cluster processing tools and other innovations in integrated circuit manufacturing environments Borisenko and Hesketh review theoretical and experimental progress in the field, discussing a wide range of materials, processes, and conditions They thoroughly cover the work of international investigators in the field

  11. Rapid Prototyping Enters Mainstream Manufacturing. (United States)

    Winek, Gary


    Explains rapid prototyping, a process that uses computer-assisted design files to create a three-dimensional object automatically, speeding the industrial design process. Five commercially available systems and two emerging types--the 3-D printing process and repetitive masking and depositing--are described. (SK)

  12. China's Tire Industry Develops Rapidly

    Institute of Scientific and Technical Information of China (English)


    @@ With strenuous efforts over many years,the tire industry in China has developed rapidly. Both the output and the exported quantity of tires already hold the leading position in the world. China has quickly become a major player in the international tire industry and is making significant impacts.

  13. Rapid-Equilibrium Enzyme Kinetics (United States)

    Alberty, Robert A.


    Rapid-equilibrium rate equations for enzyme-catalyzed reactions are especially useful because if experimental data can be fit by these simpler rate equations, the Michaelis constants can be interpreted as equilibrium constants. However, for some reactions it is necessary to use the more complicated steady-state rate equations. Thermodynamics is…

  14. Rapid Energy Modeling Workflow Demonstration (United States)


    BIM Building Information Modeling BPA Building Performance Analysis BTU British Thermal Unit CBECS Commercial Building ...geometry, orientation, weather, and materials, generates 3D Building Information Models ( BIM ) guided by satellite views of building footprints and...Rapid Energy Modeling (REM) workflows that employed building information modeling ( BIM ) approaches and conceptual energy analysis.

  15. Portable Diagnostics and Rapid Germination

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Zachary Spencer [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    In the Bioenergy and Defense Department of Sandia National Laboratories, characterization of the BaDx (Bacillus anthracis diagnostic cartridge) was performed and rapid germination chemistry was investigated. BaDx was tested with complex sample matrixes inoculated with Bacillus anthracis, and the trials proved that BaDx will detect Bacillus anthracis in a variety of the medium, such as dirt, serum, blood, milk, and horse fluids. The dimensions of the device were altered to accommodate an E. coli or Listeria lateral flow immunoassay, and using a laser printer, BaDx devices were manufactured to identify E. coli and Listeria. Initial testing with E. coli versions of BaDx indicate that the device will be viable as a portable diagnostic cartridge. The device would be more effective with faster bacteria germination; hence studies were performed the use of rapid germination chemistry. Trials with calcium dipicolinic acid displayed increased cell germination, as shown by control studies using a microplate reader. Upon lyophilization the rapid germination chemistry failed to change growth patterns, indicating that the calcium dipicolinic acid was not solubilized under the conditions tested. Although incompatible with the portable diagnostic device, the experiments proved that the rapid germination chemistry was effective in increasing cell germination.

  16. Knowledge Exchange Within the Rapid Climate Change Program (RAPID) (United States)

    Wallace, C.; Srokosz, M.


    The Rapid Climate Change Program (RAPID) is a major UK-led science program investigating the susceptibility to and risk of abrupt change in the climate system, with a particular focus on the role of the Atlantic Meridional Overturning Circulation (AMOC). RAPID commenced in 2001, with initial funding to 2008 and has just entered its second phase - RAPID-WATCH - extending some aspects of the program until 2014. Scientifically, a key focus of the program has concerned the development and deployment of a continuous AMOC observing system, although the program has also supported research into a number of other aspects of rapid climate change, including paleo studies of past rapid changes, modeling of the past and future climate, and the development of methods with which to aid the quantification of future risks. Given the societal implications that abrupt climate change associated with the AMOC may have for the North Atlantic region, a major focus within the program has been the implementation of a Knowledge Exchange strategy with which to engage key decision and policy makers within the UK political and industrial sectors. This interaction is especially pertinent for those decision makers involved in the development of adaptive capacities that must incorporate resilience to so-called high-impact, low-probability class threats. We will summarize here the main aspects of our approach, outlining activities/methods used both to satisfy the obvious need to transfer key scientific findings from the program to users, but also in facilitating a return flow of knowledge which can be used by scientists to refine the impact and utility of scientific output. We will draw on particular experience gained from the program's involvement in i: personnel exchanges with central government departments; ii: interaction and co-operation with third party stakeholder organizations (e.g. the UK Climate Impacts Program); and iii: provision of written and oral briefings. Throughout, techniques

  17. Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska. (United States)

    Gulick, Sean P S; Jaeger, John M; Mix, Alan C; Asahi, Hirofumi; Bahlburg, Heinrich; Belanger, Christina L; Berbel, Glaucia B B; Childress, Laurel; Cowan, Ellen; Drab, Laureen; Forwick, Matthias; Fukumura, Akemi; Ge, Shulan; Gupta, Shyam; Kioka, Arata; Konno, Susumu; LeVay, Leah J; März, Christian; Matsuzaki, Kenji M; McClymont, Erin L; Moy, Chris; Müller, Juliane; Nakamura, Atsunori; Ojima, Takanori; Ribeiro, Fabiana R; Ridgway, Kenneth D; Romero, Oscar E; Slagle, Angela L; Stoner, Joseph S; St-Onge, Guillaume; Suto, Itsuki; Walczak, Maureen D; Worthington, Lindsay L; Bailey, Ian; Enkelmann, Eva; Reece, Robert; Swartz, John M


    Erosion, sediment production, and routing on a tectonically active continental margin reflect both tectonic and climatic processes; partitioning the relative importance of these processes remains controversial. Gulf of Alaska contains a preserved sedimentary record of the Yakutat Terrane collision with North America. Because tectonic convergence in the coastal St. Elias orogen has been roughly constant for 6 My, variations in its eroded sediments preserved in the offshore Surveyor Fan constrain a budget of tectonic material influx, erosion, and sediment output. Seismically imaged sediment volumes calibrated with chronologies derived from Integrated Ocean Drilling Program boreholes show that erosion accelerated in response to Northern Hemisphere glacial intensification (∼ 2.7 Ma) and that the 900-km-long Surveyor Channel inception appears to correlate with this event. However, tectonic influx exceeded integrated sediment efflux over the interval 2.8-1.2 Ma. Volumetric erosion accelerated following the onset of quasi-periodic (∼ 100-ky) glacial cycles in the mid-Pleistocene climate transition (1.2-0.7 Ma). Since then, erosion and transport of material out of the orogen has outpaced tectonic influx by 50-80%. Such a rapid net mass loss explains apparent increases in exhumation rates inferred onshore from exposure dates and mapped out-of-sequence fault patterns. The 1.2-My mass budget imbalance must relax back toward equilibrium in balance with tectonic influx over the timescale of orogenic wedge response (millions of years). The St. Elias Range provides a key example of how active orogenic systems respond to transient mass fluxes, and of the possible influence of climate-driven erosive processes that diverge from equilibrium on the million-year scale.

  18. A rapidly growing lid lump (United States)

    Koay, Su-Yin; Lee, Richard M H; Hugkulstone, Charles; Rodrigues, Ian Aureliano Stephen


    A 97-year-old woman presented with a 5-month history of a rapidly growing, painless, left upper eyelid lesion. Examination revealed a large vascularised, ulcerated nodule on the left upper lid, causing significant ptosis. Wide local excision of the lesion was performed and the wound was left to heal by secondary intention. Histology and immunohistochemistry of the lesion confirmed a diagnosis of Merkel cell carcinoma, a rare primary malignancy of the eyelid which has significant morbidity and mortality. Although uncommon, this diagnosis should always be considered in any patient with a rapidly growing lid lump. In view of the patient's age, known dementia and family wishes, the patient was managed conservatively, with no further investigations performed. She was due to be followed up in clinic on a regular basis, but has since died from other causes. PMID:25123568

  19. Rapid synthesis of beta zeolites (United States)

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng


    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  20. Dispassionate Thinking amid Rapid Urbanization

    Institute of Scientific and Technical Information of China (English)


    <正> By the end of 2003, the GDP per capita of China was over US$1,000, which means that China has reached the climax of industrialization. As industrialization is a driving force for the rapid development of cities, it should be brought to the agenda to accelerate the urbanization process and expand the city scale so as to meet the requirements of economic development.

  1. Exhumation of high-pressure metamorphic terrane at the crustal levels in the Tongbai area, central China%桐柏地区高压变质地体在地壳中的抬升机制

    Institute of Scientific and Technical Information of China (English)

    崔建军; 胡健民; 刘晓春


    northern boundaries of the complex. The strike-slip directions of the shear zones are opposite; the southern boundary is a dextral ductile shear zone, and the northern boundary is a sinistral ductile one. The mylonitic foliations dip to NNE in the northern shear zone, and to SSW in the southern shear zone. In the ductile shear zones as well as the inner part of the Tongbai complex, the stretching lineations invariably dip toward SEE. On the eastern end of the complex, a south-north stretching thrust ductile shear zone occurs, in which low-angle mylonitic foliations dip toward SEE and lineations on the foliations also plunge toward SEE. These dynamic features indicate that the eastern metamorphic terrane thrusted onto the Tongbai complex with a direction of about 295° ~310°. Therefore, the Tongbai complex is actually surrounded by a huge ductile shear zone streching alone the orogen. The deformation characteristics in the shear zone and the inner part of the Tongbai complex suggest a low-angle exhumation for the HP metamorphic terrane from the east to the west along the orogen during the Early Cretaceous, which led to the HP metamorphic rocks being exhumed to the Earth' s surface from the crustal levels. Thus, the present structural observation is very important for understanding the mechanism of late exhumation of the HP/ UHP metamorphic terrane from the Tongbai-Dabie-Sulu region.

  2. Exhumation Process of the Fangdoushan-Shizhu Fold Belt in Meso-Neozoic and Its Tectonic Significance in Western Hubei-Eastern Chongqing%鄂西渝东方斗山-石柱褶皱带中新生代隆升剥蚀过程及构造意义

    Institute of Scientific and Technical Information of China (English)

    石红才; 施小斌; 杨小秋; 蒋海燕; 龙幼康


    The exhumation history of Fangdoushan-Shizhu fold belt in the Western Hubei-Eastern Chongqing since Jurassic was modeled by using combined vitrinite reflectance and apatite and zircon (U-Th)/He and apatite fission track dating methods. The results show that all samples have experienced the highest paleogeotemperature in the study area during the late Jurassic-the early Cretaceous, and from then on, the study area was always to drop in paleogeotemperature. According to the ages of apatite fission track and Ro, the denudation may be reach 3500 m during the surface of unconformity in Mesozoic-Cenozoic period. Besides, combining with the results of (U-Th)/Hemethod and vitrinite reflectance, we can get a further understanding: three tectonic phases have been revealed in the whole- rapid cooling-slow cooling-fast cooling, during the first phase, the cooling speed is about 0. 75~1. 0 ℃/Ma from the late Jurassic to the late Cretaceous (aboutl30-70Ma). Following a quiet phase with the cooling speed of 0. 33~0. 4 "C/Ma during the late Cretaceous to the end of Eocene (about 70-45 Ma), the final phase reach the maximum cooling speed which is about 0. 9~1. 1℃/Ma lasting from Eocene to nowCabout 45Ma),the three phases are correspondent with the period of three important structural changes since Middle-Trassic in the Middle-upper Yangtze. The test proves an evidence to the analysis of tectonic evolution of orogenic.%利用磷灰石与锆石(U-Th)/He年龄与磷灰石裂变径迹(AFT)、镜质组反射率(Ro)一起模拟了鄂西渝东方斗山-石柱褶皱带侏罗纪以来的构造-热演化特征.结果表明:在约130 Ma(晚侏罗世-早白垩世)研究区达到最高古地温,此后为持续抬升冷却过程.磷灰石裂变径迹与Ro表明自晚侏罗世以来不整合面剥蚀厚度可达3500m.结合(U-Th)/He与Ro数据的反演结果揭示自约130Ma开始抬升冷却后可分为三个构造演化阶段:快速冷却-缓慢冷却-快速冷却,

  3. fast,rapid,quick和speedy

    Institute of Scientific and Technical Information of China (English)



    fast,rapid,quick和speedy这组词都有“快的”意思,但将它们放在一起略作议论,仍有必要,并不乏词趣。 fast和rapid虽然有时可以互换使用,彼此仍有差异,fast在作形容词的时候,强调物体进行相对运动。如a fast horse,a fast train.除形容词外,fast可做副词。如:

  4. Rapidly Developing Toxic Epidermal Necrolysis

    Directory of Open Access Journals (Sweden)

    Viktoria Oline Barrios Poulsen


    Full Text Available Severe cutaneous reactions with potentially fatal outcomes can have many different causes. The Stevens-Johnson syndrome (SJS and toxic epidermal necrolysis (TEN are rare. They are characterized by a low incidence but high mortality, and drugs are most commonly implicated. Urgent active therapy is required. Prompt recognition and withdrawal of suspect drug and rapid intervention can result in favourable outcome. No further international guidelines for treatment exist, and much of the treatment relies on old or experimental concepts with no scientific evidence. We report on a 54-year-old man experiencing rapidly developing drug-induced severe TEN and presented multiorgan failure involving the respiratory and circulatory system, coagulopathy, and renal insufficiency. Detachment counted 30% of total body surface area (TBSA. SCORTEN = 5, indicating a mortality rate >90%. The patient was sedated and mechanically ventilated, supported with fluids and inotropes to maintain a stable circulation. Component therapy was guided by thromboelastography (TEG. The patient received plasmapheresis, and shock reversal treatment was initiated. He was transferred to a specialized intensive care burn unit within 24 hours from admittance. The initial care was continued, and hemodialysis was started. Pulmonary, circulatory, and renal sequelae resolved with intensive care, and re-epithelialization progressed slowly. The patient was discharged home on hospital day 19.

  5. QCD factorization at forward rapidities (United States)

    Čepila, J.; Nemchik, J.; Šumbera, M.


    We analyze particle production in several reactions on nuclear targets at forward rapidities and different energies. The forward kinematic region at high energies allows to access the smallest Bjorken x. Nuclear effects are then usually interpreted as a result of the coherence effects associated with shadowing or the Color Glass Condensate. QCD factorization of soft and hard interactions requires the nucleus to be an universal filter for different Fock components of the projectile hadron. We demonstrate, however, that this is not the case in the vicinity of the kinematic limit, x → 1, where sharing of energy between the projectile constituents becomes an issue. The rise of suppression of particle production with x is confirmed by the E772 and E886 data on Drell-Yan and heavy quarkonia. We show that this effect can also be treated alternatively as an effective energy loss proportional to initial energy. This leads to a nuclear suppression at any energy, and predicts Feynman xF scaling of the suppression. We demonstrate how the kinematic limit influences the high-pT particle production at mid-rapidity where the Cronin enhancement at medium-high pT switches to a suppression at larger pT violating thus QCD factorization. Such an expectation seems to be confirmed by RHIC data for pion and direct photon production. We show that this effect as an additional large-pT suppression significantly revises calculations for jet quenching in heavy ion collisons at RHIC.

  6. Rapid Geophysical Surveyor. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Roybal, L.G.; Carpenter, G.S.; Josten, N.E.


    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of US Department of Energy waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sites where historical records are inaccurate and survey benchmarks have changed because of refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho National Engineering Laboratory (INEL) during the summer of 1992. The RGS was funded by the Buried Waste Integrated Demonstration program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex at the INEL in September 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2{1/2} in. along survey lines spaced 1-ft apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 worker-days using conventional ground survey techniques.


    Energy Technology Data Exchange (ETDEWEB)

    Costa, A. D.; Martins, B. L. Canto; Bravo, J. P.; Paz-Chinchón, F.; Chagas, M. L. das; Leão, I. C.; Oliveira, G. Pereira de; Silva, R. Rodrigues da; Roque, S.; Oliveira, L. L. A. de; Silva, D. Freire da; De Medeiros, J. R., E-mail: [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitário, Natal RN (Brazil)


    Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of substellar companions by their hosting stars. In the present Letter, we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time, the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting a very short rotation period with values ranging from 13 to 55 days. This finding points to remarkable surface rotation rates, up to 18 times the rotation of the Sun. These giants are combined with six others recently listed in the literature for mid-infrared (IR) diagnostics based on Wide-field Infrared Survey Explorer information, from which a trend for an IR excess is revealed for at least one-half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

  8. Kepler rapidly rotating giant stars

    CERN Document Server

    Costa, A D; Bravo, J P; Paz-Chinchón, F; Chagas, M L das; Leão, I C; de Oliveira, G Pereira; da Silva, R Rodrigues; Roque, S; de Oliveira, L L A; da Silva, D Freire; De Medeiros, J R


    Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of sub-stellar companions by their hosting stars. In the present letter we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting very short rotation period with values ranging from 13 to 55 days. This finding points for remarkable surface rotation rates, up to 18 times the Sun rotation. These giants are combined with 6 other recently listed in the literature for mid-IR diagnostic based on WISE information, from which a trend for an infrared excess is revealed for at least a half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

  9. Rapidly rotating neutron star progenitors

    CERN Document Server

    Postnov, K A; Kolesnikov, D A; Popov, S B; Porayko, N K


    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In the present paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, $\\tau_c$. The validity of this approach is checked by direct MESA calculations ...

  10. Rapidly rotating neutron star progenitors (United States)

    Postnov, K. A.; Kuranov, A. G.; Kolesnikov, D. A.; Popov, S. B.; Porayko, N. K.


    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In this paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE (Binary Star Evolution) population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, τc. The validity of this approach is checked by direct MESA calculations of the evolution of a rotating 15 M⊙ star. From comparison of the calculated spin distribution of young neutron stars with the observed one, reported by Popov and Turolla, we infer the value τc ≃ 5 × 105 yr. We show that merging of stellar cores in common envelopes can lead to collapses with dynamically unstable proto-neutron stars, with their formation rate being ˜0.1-1 per cent of the total core collapses, depending on the common envelope efficiency.

  11. Rapidly rotating neutron star progenitors (United States)

    Postnov, K. A.; Kuranov, A. G.; Kolesnikov, D. A.; Popov, S. B.; Porayko, N. K.


    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In the present paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, τc. The validity of this approach is checked by direct MESA calculations of the evolution of a rotating 15 M⊙ star. From comparison of the calculated spin distribution of young neutron stars with the observed one, reported by Popov and Turolla, we infer the value τc ≃ 5 × 105 years. We show that merging of stellar cores in common envelopes can lead to collapses with dynamically unstable proto-neutron stars, with their formation rate being ˜0.1 - 1% of the total core collapses, depending on the common envelope efficiency.

  12. Late Paleozoic onset of subduction and exhumation at the western margin of Gondwana (Chilenia Terrane): Counterclockwise P-T paths and timing of metamorphism of deep-seated garnet-mica schist and amphibolite of Punta Sirena, Coastal Accretionary Complex, central Chile (34° S) (United States)

    Hyppolito, T.; García-Casco, A.; Juliani, C.; Meira, V. T.; Hall, C.


    In this study, the Paleozoic albite-epidote-amphibolite occurring as meter-sized intercalations within garnet-mica schist at Punta Sirena beach (Pichilemu region, central Chile) is characterized for the first time. These rocks constitute an unusual exposure of subduction-related rocks within the Paleozoic Coastal Accretionary Complex of central Chile. Whereas high pressure (HP) greenschist and cofacial metasediments are the predominant rocks forming the regional metamorphic basement, the garnet-mica schist and amphibolite yield higher P-T conditions (albite-epidote amphibolite facies) and an older metamorphic age. Combining detailed mineral chemistry and textural information, P-T calculations and Ar-Ar ages, including previously published material from the Paleozoic Accretionary Complex of central Chile, we show that the garnet-mica schist and associated amphibolite (locally retrograded to greenschist) are vestiges of the earliest subducted material now forming exotic bodies within the younger HP units of the paleo-accretionary wedge. These rocks are interpreted as having been formed during the onset of subduction at the southwestern margin of Gondwana. However, we show that the garnet-mica schist formed at a slightly greater depth (ca. 40 km) than the amphibolite (ca. 30 km) along the same hot-subduction gradient developed during the onset of subduction. Both lithotypes reached their peak-P conditions at ca. 335-330 Ma and underwent near-isobaric cooling followed by cooling and decompression (i.e., counterclockwise P-T paths). The forced return flow of the garnet-mica schist from the subduction channel started at ca. 320 Ma and triggered the exhumation of fragments of shallower accreted oceanic crust (amphibolite). Cores of phengite (garnet-mica schist) and amphibole (amphibolite) grains have similar chemical compositions in both the S1 and S2 domains, indicating rotation of these grains during the transposition of the burial-related (prograde peak-T) foliation S1

  13. Reconstruction of methods of execution of the death penalty by shooting in the years 1949-1954 based on exhumation research of "prison fields" in Osobowicki Cemetery in Wroclaw. Part II--analysis of gunshot injuries and an attempt at reconstructing the course of execution. (United States)

    Szleszkowski, Łukasz; Thannhäuser, Agata; Kawecki, Jerzy; Szwagrzyk, Krzysztof; Swiatek, Barbara


    The analysis of gunshot injuries in prisoners who were executed in Wroclaw penitentiary in the years 1949-1954 shows divergences from legal regulations describing the method of execution. This observation leads to the conclusion that the predominant method of execution of the death penalty was a gunshot or gunshots to the back of the head, which is analogous to the results of exhumation works on collective graves of war prisoners executed during World War II in the territory of the former Soviet Union.

  14. Customer-experienced rapid prototyping (United States)

    Zhang, Lijuan; Zhang, Fu; Li, Anbo


    In order to describe accurately and comprehend quickly the perfect GIS requirements, this article will integrate the ideas of QFD (Quality Function Deployment) and UML (Unified Modeling Language), and analyze the deficiency of prototype development model, and will propose the idea of the Customer-Experienced Rapid Prototyping (CE-RP) and describe in detail the process and framework of the CE-RP, from the angle of the characteristics of Modern-GIS. The CE-RP is mainly composed of Customer Tool-Sets (CTS), Developer Tool-Sets (DTS) and Barrier-Free Semantic Interpreter (BF-SI) and performed by two roles of customer and developer. The main purpose of the CE-RP is to produce the unified and authorized requirements data models between customer and software developer.

  15. Rapid Adaptation in Digital Transformation

    DEFF Research Database (Denmark)

    Hansen, Anne Mette; Kræmmergaard, Pernille; Mathiassen, Lars


    the organization’s digitization approach. We demonstrate in detail how the leaders within these two organizations were engaged and offer recommendations for how other organizations can use the PPM to rapidly adapt their approaches to digital transformation through more effective IS leadership roles.......In today’s highly dynamic environments, organizational leaders need to quickly adapt existing approaches to digital transformation. However, without a shared mindset between IS and business leaders, it is difficult to adopt new approaches in response to changes in the competitive and technology...... landscape. In this article, we share insights gained from two public sector organizations in which IS and business leaders used the Participatory Process Model (PPM) designed by the authors to share their assumptions about IS leadership, challenge existing IT strategies and collaboration patterns and adapt...

  16. Rapid solidification of immiscible alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Enrica; Rizzi, Paola; Baricco, Marcello E-mail:


    Immiscible alloys have been rapidly solidified for the preparation of granular materials with giant magnetoresistance properties. Au-based (Au-Co and Au-Fe) and Cu-based (Cu-Co and Cu-Fe) systems have been investigated. Single supersaturated solid solution has been obtained for Au-Fe, whereas three FCC solid solutions with different Co content have been found for Au-Co. For Cu-Co and Cu-Fe a limit of solubility in Cu has been observed. Ni additions to Cu-Fe strongly enhance solid solubility. A thermodynamic analysis has been used to describe the competition between partition-less solidification and phase separation in undercooled liquid.

  17. Silicone:Worries behind Rapid Growth

    Institute of Scientific and Technical Information of China (English)


    @@ Rapid consumption growth Silicone's extensive application scope, sustained production growth and constant technology improvements have benefited from the rapid development of China's economy overall, and particularly the boom in the manufacturing sector.

  18. Master-Batch Sector Develops Rapidly

    Institute of Scientific and Technical Information of China (English)

    Wu Lifeng


    @@ Plastic industry promotes the development of the master-batch sector The plastic processing industry in China has developed rapidly. The output is increasing rapidly and the quality is improving constantly.

  19. Rapid purification of recombinant histones.

    Directory of Open Access Journals (Sweden)

    Henrike Klinker

    Full Text Available The development of methods to assemble nucleosomes from recombinant histones decades ago has transformed chromatin research. Nevertheless, nucleosome reconstitution remains time consuming to this day, not least because the four individual histones must be purified first. Here, we present a streamlined purification protocol of recombinant histones from bacteria. We termed this method "rapid histone purification" (RHP as it circumvents isolation of inclusion bodies and thereby cuts out the most time-consuming step of traditional purification protocols. Instead of inclusion body isolation, whole cell extracts are prepared under strongly denaturing conditions that directly solubilize inclusion bodies. By ion exchange chromatography, the histones are purified from the extracts. The protocol has been successfully applied to all four canonical Drosophila and human histones. RHP histones and histones that were purified from isolated inclusion bodies had similar purities. The different purification strategies also did not impact the quality of octamers reconstituted from these histones. We expect that the RHP protocol can be readily applied to the purification of canonical histones from other species as well as the numerous histone variants.

  20. Rapid Response Flood Water Mapping (United States)

    Policelli, Fritz; Brakenridge, G. R.; Coplin, A.; Bunnell, M.; Wu, L.; Habib, Shahid; Farah, H.


    Since the beginning of operation of the MODIS instrument on the NASA Terra satellite at the end of 1999, an exceptionally useful sensor and public data stream have been available for many applications including the rapid and precise characterization of terrestrial surface water changes. One practical application of such capability is the near-real time mapping of river flood inundation. We have developed a surface water mapping methodology based on using only bands 1 (620-672 nm) and 2 (841-890 nm). These are the two bands at 250 m, and the use of only these bands maximizes the resulting map detail. In this regard, most water bodies are strong absorbers of incoming solar radiation at the band 2 wavelength: it could be used alone, via a thresholding procedure, to separate water (dark, low radiance or reflectance pixels) from land (much brighter pixels) (1, 2). Some previous water mapping procedures have in fact used such single band data from this and other sensors that include similar wavelength channels. Adding the second channel of data (band 1), however, allows a band ratio approach which permits sediment-laden water, often relatively light at band 2 wavelengths, to still be discriminated, and, as well, provides some removal of error by reducing the number of cloud shadow pixels that would otherwise be misclassified as water.

  1. 78 FR 11678 - Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI (United States)


    ... National Park Service Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: The Grand Rapids Public Museum has completed an... Grand Rapids Public Museum. Repatriation of the human remains and associated funerary objects to...

  2. 77 FR 11575 - Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI (United States)


    ... National Park Service Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: The Grand Rapids Public Museum has completed an... Rapids Public Museum. Repatriation of the human remains and associated funerary objects to the...


    Institute of Scientific and Technical Information of China (English)

    GUDong-qing; QINYong-yuan; PENGRong; LIXin


    The dimension number of the centralized Kalman filter (CKF) for the rapid transfer alignment (TA) is as high as 21 if the aircraft wing flexure motion is considered in the rapid TA. The 21-dimensional CKF brings the calculation burden on the computer and the difficulty to meet a high filtering updating rate desired by rapid TA. The federated Kalman filter (FKF) for the rapid TA is proposed to solve the dilemma. The structure and the algorithm of the FKF, which can perform parallel computation and has less calculation burden, are designed.The wing flexure motion is modeled, and then the 12-order velocity matching local filter and the 15-order attitud ematching local filter are devised. Simulation results show that the proposed EKE for the rapid TA almost has the same performance as the CKF. Thus the calculation burden of the proposed FKF for the rapid TA is markedly decreased.

  4. Rapid Automated Mission Planning System Project (United States)

    National Aeronautics and Space Administration — The proposed innovation is an automated UAS mission planning system that will rapidly identify emergency (contingency) landing sites, manage contingency routing, and...

  5. Rapidity Correlation Structures from Causal Hydrodynamics

    CERN Document Server

    Gavin, Sean; Zin, Christopher


    Viscous diffusion can broaden the rapidity dependence of two-particle transverse momentum fluctuations. Surprisingly, measurements at RHIC by the STAR collaboration demonstrate that this broadening is accompanied by the appearance of unanticipated structure in the rapidity distribution of these fluctuations in the most central collisions. Although a first order classical Navier-Stokes theory can roughly explain the rapidity broadening, it cannot explain the additional structure. We propose that the rapidity structure can be explained using the second order causal Israel-Stewart hydrodynamics with stochastic noise.

  6. Set point calculations for RAPID project

    Energy Technology Data Exchange (ETDEWEB)



    The Respond and Pump in Days (RAPID) project was initiated to pump part of the contents of tank 241-SY-101 into tank 241-SY-102. This document establishes the basis for all set points and ranges used in the RAPID project.

  7. Rapid methods for detection of bacteria

    DEFF Research Database (Denmark)

    Corfitzen, Charlotte B.; Andersen, B.Ø.; Miller, M.


    Traditional methods for detection of bacteria in drinking water e.g. Heterotrophic Plate Counts (HPC) or Most Probable Number (MNP) take 48-72 hours to give the result. New rapid methods for detection of bacteria are needed to protect the consumers against contaminations. Two rapid methods...

  8. Rapid optical variations in KT Eri

    CERN Document Server

    Ilkiewicz, K; Galan, C; Cikala, M; Tomov, T


    We present optical photometric monitoring of KT Eri (Nova Eridani 2009), a He/N very fast nova which oubursted in November 2009. Our observations include BVRcIc brightness estimations as well as monitoring of the rapid brightness variations in V band. The characteristic times of these rapid changes are studied and compared with the observed in other novae.

  9. Rapid eye movement sleep behavior disorder

    DEFF Research Database (Denmark)

    Schenck, C H; Montplaisir, J Y; Frauscher, B


    We aimed to provide a consensus statement by the International Rapid Eye Movement Sleep Behavior Disorder Study Group (IRBD-SG) on devising controlled active treatment studies in rapid eye movement sleep behavior disorder (RBD) and devising studies of neuroprotection against Parkinson disease (PD...

  10. A new method for rapid Canine retraction

    Directory of Open Access Journals (Sweden)

    "Khavari A


    Full Text Available Distraction osteogenesis method (Do in bone lengthening and rapid midpalatal expansion have shown the great ability of osteognic tissues for rapid bone formation under distraction force and special protocol with optimum rate of one millimeter per day. Periodontal membrane of teeth (PDM is the extension of periostium in the alveolar socked. Orthodontic force distracts PDM fibers in the tension side and then bone formation will begin.Objects: Rapid retraction of canine tooth into extraction space of first premolar by DO protocol in order to show the ability of the PDM in rapid bone formation. The other objective was reducing total orthodontic treatment time of extraction cases.Patients and Methods: Tweleve maxillary canines in six patients were retracted rapidly in three weeks by a custom-made tooth-born appliance. Radiographic records were taken to evaluate the effects of heavy applied force on canine and anchorage teeth.Results: Average retraction was 7.05 mm in three weeks (2.35 mm/week. Canines rotated distal- in by mean 3.5 degrees.Anchorage loss was from 0 to 0.8 mm with average of 0.3 mm.Root resorption of canines was negligible, and was not significant clinically. Periodontium was normal after rapid retraction. No hazard for pulp vitality was observed.Discussion: PDM responded well to heavy distraction force by Do protocol. Rapid canine retraction seems to be a safe method and can considerabely reduce orthodontic time.

  11. Risks and benefits of rapid clozapine titration

    Directory of Open Access Journals (Sweden)

    Jeannie D. Lochhead


    Full Text Available Clozapine is often considered the gold standard for the treatment of schizophrenia. Clinical guidelines suggest a gradual titration over 2 weeks to reduce the risks of adverse events such as seizures, hypotension, agranulocytosis, and myocarditis. The slow titration often delays time to therapeutic response. This raises the question of whether, in some patients, it may be safe to use a more rapid clozapine titration. The following case illustrates the potential risks associated with the use of multiple antipsychotics and rapid clozapine titration. We present the case of a young man with schizophrenia who developed life threatening neuroleptic malignant syndrome (NMS during rapid clozapine titration and treatment with multiple antipsychotics. We were unable to find another case in the literature of NMS associated with rapid clozapine titration. This case is meant to urge clinicians to carefully evaluate the risks and benefits of rapid clozapine titration, and to encourage researchers to further evaluate the safety of rapid clozapine titration. Rapid clozapine titration has implications for decreasing health care costs associated with prolonged hospitalizations, and decreasing the emotional suffering associated with uncontrolled symptoms of psychosis. Clozapine is considered the most effective antipsychotic available thus efforts should focus on developing strategies that would allow for safest and most efficient use of clozapine to encourage its utilization for treatment resistance schizophrenia.

  12. Hadron rapidity spectra within a hybrid model

    CERN Document Server

    Khvorostukhin, A S


    A 2-stage hybrid model is proposed that joins the fast initial state of interaction, described by the hadron string dynamics (HSD) model, to subsequent evolution of the expanding system at the second stage, treated within ideal hydrodynamics. The developed hybrid model is assigned to describe heavy-ion collisions in the energy range of the NICA collider under construction in Dubna. Generally, the model is in reasonable agreement with the available data on proton rapidity spectra. However, reproducing proton rapidity spectra, our hybrid model cannot describe the rapidity distributions of pions. The model should be improved by taking into consideration viscosity effects at the hydrodynamical stage of system evolution.

  13. [Rapidly vanishing hip--a mystery]. (United States)

    Keren, Yaniv; Sigal, Amit; Greental, Arnan; Vlodavsky, Euvgeni; Soudry, Michael; Militianu, Daniela


    Rapidly destructive hip disease is a rare condition, the cause of which is yet to be clarified, and is described in the literature by scant case reports. The disease was first described by Forestier in 1957, and since then many names have been proposed to describe the rapid vanishing of the femoral head, and occasionally the acetabulum. This condition initially represents as acute hip pain, and rapidly progresses to complete vanishing of the proximal femur, within a few months. We briefly discuss the literature regarding this phenomenon, and describe a case of a female patient who suffered from complete disappearance of the femoral head within 9 weeks.

  14. New developments in rapidly solidified magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.K. [Allied-Signal, Inc., Morristown, NJ (United States); Chang, C.F. [Allied-Signal, Inc., Morristown, NJ (United States); Raybould, D. [Allied-Signal, Inc., Morristown, NJ (United States); King, J.F. [Magnesium Elektron Ltd., Manchester (United Kingdom); Thistlethwaite, S. [Magnesium Elektron Ltd., Manchester (United Kingdom)


    In the present paper, we will examine the new developments in the rapidly solidified Mg-Al-Zn-Nd (EA55RS) alloy. We shall first briefly review the process scale-up currently employed for producing rapidly solidified magnesium alloys in large quantities, and then discuss the effect of billet size and processing parameters on the mechanical properties of various mill product forms such as extrusions and sheets. The superplastic behavior of EA55RS extrusions and rolled sheets are also discussed. Finally, some results on magnesium metal-matrix composites using rapidly solidified EA55RS matrix powders and SiC particulates are presented. (orig.)

  15. Cation distributions on rapidly solidified cobalt ferrite (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.


    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  16. Syn-collisional exhumation of Sumdo eclogite in the Lhasa Terrane, Tibet: Evidences from structural deformation and 40Ar-39Ar geochronology.%拉萨地体内松多榴辉岩的同碰撞折返:来自构造变形和40Ar-39Ar年代学的证据

    Institute of Scientific and Technical Information of China (English)

    李化启; 许志琴; 杨经绥; 唐哲民; 杨梅


    松多地区的区域构造变形与糜棱质白云母石英片岩和绿片岩的白云母单矿物40Ar-39Ar年代学测试表明拉萨地体内的松多地区于220~240 Ma经历过印支期碰撞造山事件.这次造山事件为晚二叠世松多榴辉岩带代表的古特提斯洋盆消失闭合之后北拉萨地体与南冈瓦那大陆碰撞的结果.该区榴辉岩与退变榴辉岩白云母和角闪石的40Ar-39Ar测年结果也为220~240 Ma,且退变榴辉岩经历了与围岩一致的同构造变形,说明榴辉岩折返退变的时代和碰撞造山的时代一致.即碰撞造山的强挤压及挤压转换作用应是本区榴辉岩折返出露的主要机制.拉萨地体内印支晚期(210~190 Ma)大规模花岗岩带的发育从另一个侧面说明松多榴辉岩的折返与造山后伸展和区域内大规模花岗岩浆活动等后期热事件没关系,应为同碰撞折返机制.研究结果为高压变质岩石的同碰撞折返研究提供了一个具体实例和翔实的地质资料.%The structural deformation and muscovite and amphibole 40Ar-39Ar dating of muscovite quartz schist,eclogite and retrograde eclogite indicate that an Indosinian orogenesis occurred in 220 - 240 Ma in the Lhasa Terrane, which caused the closure of Paleo-Tethys ocean basin and the collision between the northern Lhasa Terrane and southern Gondwana. The accordance of muscovite and amphibole 40Ar-39Ar dating among eclogite,retrograde eclogite and muscovite quartz schist shows that the eclogite exhumation and Indosinian collisional orogenesis occurred simultaneously, which suggests that the regional ductile extrusion should be the main mechanism for the exhumation of Sumdo eclogite. The existence of large scale granite belt of late Indochina EPoch in the Lhasa Terrane, with the high precision single zircon U-Pb ages of 210 - 190 Ma, confirms the syn-collisional exhumation of eclogite from the another side, indicating that the eclogite exhumation had no relation to the

  17. The Rapid Perceptual Impact of Emotional Distractors.

    Directory of Open Access Journals (Sweden)

    Briana L Kennedy

    Full Text Available The brief presentation of an emotional distractor can temporarily impair perception of a subsequent, rapidly presented target, an effect known as emotion-induced blindness (EIB. How rapidly does this impairment unfold? To probe this question, we examined EIB for targets that immediately succeeded ("lag-1" emotional distractors in a rapid stream of items relative to EIB for targets at later serial positions. Experiments 1 and 2 suggested that emotional distractors interfere with items presented very soon after them, with impaired target perception emerging as early as lag-1. Experiment 3 included an exploratory examination of individual differences, which suggested that EIB onsets more rapidly among participants scoring high in measures linked to negative affect.

  18. Soft-/rapidity- anomalous dimensions correspondence

    CERN Document Server

    Vladimirov, Alexey A


    We establish a correspondence between ultraviolet singularities of soft factors for multi-particle production and rapidity singularities of soft factors for multi-parton scattering. This correspondence is a consequence of a conformal mapping between scattering geometries. The correspondence is valid to all orders of perturbation theory and in this way provides a proof of rapidity renormalization procedure for multi-parton scattering soft factors (including the transverse momentum dependent (TMD) soft factor as a special case). As a by-product we obtain an exact relation between the rapidity anomalous dimension and the well-known soft anomalous dimension. The three-loop rapidity anomalous dimensions for TMD and a general multi-parton scattering are derived.

  19. Rapid Development of the Radiation Curing Sector

    Institute of Scientific and Technical Information of China (English)


    @@ Radiation curing is an advanced material surface treatment technology using ultraviolet (UV) radiation and electronic beams (EB). With the greater attention paid to environ mentel protection in recent years ,radiation curing has developed rapidly.

  20. Colorado Plateau Rapid Ecoregion Assessment Data Catalog (United States)

    Bureau of Land Management, Department of the Interior — Datasets used in the analysis of the Colorado Plateau (COP) Rapid Ecoregion Assessment (REA).They can be downloaded via a layer package (lpk, similar to a zip file...

  1. Rapid Update Cycle (RUC) [13 km (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Update Cycle (RUC) weather forecast model was developed by the National Centers for Environmental Prediction (NCEP). On May 1, 2012, the RUC was replaced...

  2. Rapid Update Cycle (RUC) [20 km (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Update Cycle (RUC) weather forecast model was developed by the National Centers for Environmental Prediction (NCEP). On May 1, 2012, the RUC was replaced...

  3. Ceramic microfabrication by rapid prototyping process chains

    Indian Academy of Sciences (India)

    R Knitter; W Bauer


    Fabrication of micropatterned ceramics or ceramic microparts make high demands on the precision and resolution of the moulding process. As finishing of miniaturised or micropatterned ceramic components is nearly impossible, shaping has to be done by a replication step in the green, unfired state. To avoid high tooling costs in product development, a rapid prototyping process chain has been established that enables rapid manufacturing of ceramic microcomponents from functional models to small lot series within a short time. This process chain combines the fast and inexpensive supply of master models by rapid prototyping with accurate and flexible ceramic manufacturing by low-pressure injection moulding. Besides proper feedstock preparation and sufficient small grain size, the quality of the final components is mainly influenced by the quality of the master model. Hence, the rapid prototyping method must be carefully selected to meet the requirements of the component to be fabricated.

  4. Exploring data with RapidMiner

    CERN Document Server

    Chisholm, Andrew


    A step-by-step tutorial style using examples so that users of different levels will benefit from the facilities offered by RapidMiner.If you are a computer scientist or an engineer who has real data from which you want to extract value, this book is ideal for you. You will need to have at least a basic awareness of data mining techniques and some exposure to RapidMiner.

  5. Rapid coal proximate analysis by thermogravimetric method

    Energy Technology Data Exchange (ETDEWEB)

    Mao Jianxiong; Yang Dezhong; Zhao Baozhong


    A rapid coal proximate analysis by thermogravimetric analysis (TGA) can be used as an alternative method for the standard proximate analysis. This paper presents a program set up to rapidly perform coal proximate analysis by using a thermal analyzer and TGA module. A comparison between coal proximate analyses by standard method (GB) and TGA is also given. It shows that most data from TGA fall within the tolerance limit of standard method.

  6. Second international symposium rapid mine development. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Martens, P.N. (ed.)


    'Rapid Mine Development', synonymous for increase in efficiency of mine development and infrastructure, is today a prerequisite for high performance operations. The presentations printed in this volume were held on June 7th and 8th 2006 on occasion of the second International Symposium 'Rapid Mine Development' at the Institute of Mining Engineering I at the RWTH Aachen University. 38 international papers demonstrate different aspects and innovations for more efficient mine development including infrastructure. (orig.)

  7. Modified TB rapid test by proteinase K for rapid diagnosis of pleural tuberculosis. (United States)

    Yari, Shamsi; Hadizadeh Tasbiti, Alireza; Ghanei, Mostafa; Shokrgozar, Mohammad Ali; Fateh, Abolfazl; Yari, Fatemeh; Bahrmand, Ahmadreza


    The diagnosis of pleural tuberculosis continues to be a challenge due to the low sensitivity of traditional diagnostic methods. Better and more rapid tests are needed for diagnosis of pleural TB. In this study, pleural fluids were tested with rapid test to determine Mycobacterium tuberculosis (MTB antigen). Affinity chromatography was used to purify specific polyclonal antibodies against MTB antigen. Pleural samples after decontamination were treated with proteinase K. Rapid test for pleural fluids was prepared by specific antibody. Rapid test was performed on 85 pleural fluid patients. The patients had a mean age of 46.55 ± 15.96 years and 38 were men. The performance of rapid test, using proteinase K, was found to be the most impressive: sensitivity 93%, specificity 94%, PPV 90%, and NPV 96% compared with adenosine deaminase test (ADA), PCR, smear, and culture. The present study did demonstrate that modified TB rapid test can substantially improve the diagnosis of extrapulmonary TB.

  8. Prostate treatments, 1MRT o RapidArc; Tratamiento de prostata, IMART o RapidArc?

    Energy Technology Data Exchange (ETDEWEB)

    Castro novais, J.; Ruiz Maqueda, S.; Pardo Perez, E.; Molina Lopez, M. Y.; Cerro Penalver, E.


    Techniques that modulate the dose (as IMRT or RapidArcTM) improve dose homogeneity within the target volume decreasing the dose in healthy organs. The aim of this work is to study the dosimetric differences in prostate radiotherapy treatments with IMRT and RapidArcTM. The results of the 109 patients studied show that plans to RapidArcTM have better coverage, compliance and dose gradient outside the target volume. (Author)

  9. An Exponential Regulator for Rapidity Divergences

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ye [Fermilab; Neill, Duff [MIT, Cambridge, CTP; Zhu, Hua Xing [MIT, Cambridge, CTP


    Finding an efficient and compelling regularization of soft and collinear degrees of freedom at the same invariant mass scale, but separated in rapidity is a persistent problem in high-energy factorization. In the course of a calculation, one encounters divergences unregulated by dimensional regularization, often called rapidity divergences. Once regulated, a general framework exists for their renormalization, the rapidity renormalization group (RRG), leading to fully resummed calculations of transverse momentum (to the jet axis) sensitive quantities. We examine how this regularization can be implemented via a multi-differential factorization of the soft-collinear phase-space, leading to an (in principle) alternative non-perturbative regularization of rapidity divergences. As an example, we examine the fully-differential factorization of a color singlet's momentum spectrum in a hadron-hadron collision at threshold. We show how this factorization acts as a mother theory to both traditional threshold and transverse momentum resummation, recovering the classical results for both resummations. Examining the refactorization of the transverse momentum beam functions in the threshold region, we show that one can directly calculate the rapidity renormalized function, while shedding light on the structure of joint resummation. Finally, we show how using modern bootstrap techniques, the transverse momentum spectrum is determined by an expansion about the threshold factorization, leading to a viable higher loop scheme for calculating the relevant anomalous dimensions for the transverse momentum spectrum.

  10. Rapid, generalized adaptation to asynchronous audiovisual speech. (United States)

    Van der Burg, Erik; Goodbourn, Patrick T


    The brain is adaptive. The speed of propagation through air, and of low-level sensory processing, differs markedly between auditory and visual stimuli; yet the brain can adapt to compensate for the resulting cross-modal delays. Studies investigating temporal recalibration to audiovisual speech have used prolonged adaptation procedures, suggesting that adaptation is sluggish. Here, we show that adaptation to asynchronous audiovisual speech occurs rapidly. Participants viewed a brief clip of an actor pronouncing a single syllable. The voice was either advanced or delayed relative to the corresponding lip movements, and participants were asked to make a synchrony judgement. Although we did not use an explicit adaptation procedure, we demonstrate rapid recalibration based on a single audiovisual event. We find that the point of subjective simultaneity on each trial is highly contingent upon the modality order of the preceding trial. We find compelling evidence that rapid recalibration generalizes across different stimuli, and different actors. Finally, we demonstrate that rapid recalibration occurs even when auditory and visual events clearly belong to different actors. These results suggest that rapid temporal recalibration to audiovisual speech is primarily mediated by basic temporal factors, rather than higher-order factors such as perceived simultaneity and source identity.

  11. Open architecture for rapid deployment of capability (United States)

    Glassman, Jacob


    Modern warfare has drastically changed from conventional to non-conventional and from fixed threats to dynamic ones over the past several decades. This unprecedented fundamental shift has now made our adversaries and their weapons more nebulous and ever changing. Our current acquisition system however is not suited to develop, test and deploy essential capability to counter these dynamic threats in time to combat them. This environment requires a new infrastructure in our system design to rapidly adopt capabilities that we do not currently plan for or even know about. The key to enabling this rapid implementation is Open Architecture in acquisition. The DoD has shown it can rapidly prototype capabilities such as unmanned vehicles but has severely struggled in moving from the prototyping to deployment. A major driver of this disconnect is the lack of established infrastructure to employ said capability such as launch and recovery systems and command and control. If we are to be successful in transitioning our rapid capability to the warfighter we must implement established well defined interfaces and enabling technologies to facilitate the rapid adoption of capability so the warfighter has the tools to effectively counter the threat.

  12. Rapid penetration into granular media visualizing the fundamental physics of rapid earth penetration

    CERN Document Server

    Iskander, Magued


    Rapid Penetration into Granular Media: Visualizing the Fundamental Physics of Rapid Earth Penetration introduces readers to the variety of methods and techniques used to visualize, observe, and model the rapid penetration of natural and man-made projectiles into earth materials. It provides seasoned practitioners with a standard reference that showcases the topic's most recent developments in research and application. The text compiles the findings of new research developments on the subject, outlines the fundamental physics of rapid penetration into granular media, and assembles a com

  13. Rapid natural resolution of intracranial hematoma

    Institute of Scientific and Technical Information of China (English)

    吴明灿; 刘建雄; 罗国才; 张志文; 闵杰; 余辉; 姚远


    Objective:To investigate the clinical characteristics of intracranial hematoma and the mechanism involved in its rapid natural resolution. Methods:Seventeen cases of intracranial hematoma with typical clinical and CT manifestations were retrospectively studied. Results: Intracranial hematoma was found obviously decreased in size within 72 h after its occurrence in 8 cases. The rest 9 cases presented complete resolution. Conclusions: Rapid natural resolution of acute epidural hematoma is mostly found in teenagers and the resolution is correlated with cranial fracture at the hematoma site. As for acute subdural hematoma, its rapid resolution is associated with the transfer of cerebrospinal fluid toward subdural space, the lavage effect, and the compression caused by the increased intracranial pressure or the space left resulting from redistribution of the hematoma in brain atrophy.

  14. Wreathes of Magnetism in Rapidly Rotating Suns

    CERN Document Server

    Brown, Benjamin P; Brun, Allan Sacha; Toomre, Juri


    When our Sun was young it rotated much more rapidly than now. Observations of young, rapidly rotating stars indicate that many possess substantial magnetic activity and strong axisymmetric magnetic fields. We conduct simulations of dynamo action in rapidly rotating suns with the 3-D MHD anelastic spherical harmonic (ASH) code to explore the complex coupling between rotation, convection and magnetism. Here we study dynamo action realized in the bulk of the convection zone for two systems, rotating at three and five times the current solar rate. We find that substantial organized global-scale magnetic fields are achieved by dynamo action in these systems. Striking wreathes of magnetism are built in the midst of the convection zone, coexisting with the turbulent convection. This is a great surprise, for many solar dynamo theories have suggested that a tachocline of penetration and shear at the base of the convection zone is a crucial ingredient for organized dynamo action, whereas these simulations do not includ...

  15. Rapid Hepatitis B Vaccination in Adults

    Directory of Open Access Journals (Sweden)

    Mansur Özcan


    Full Text Available Vaccination is a very important method in prevention of HBV.Especially rapid immunization takes an important place in subjects at highrisk. We have injected HBV vaccine to health workers who are attending inour hospital by rapid immunisation programme (at 0, 1 and 2 months andaimed to identify it’s efficiacy. Eighty seven subjects (69% male, 31%female were included to our study. Median age was 34 for male and 32 forwomen. We obtained 90% achievement of immunity rate after theprogramme finished. There were no significant difference between maleend female groups, and age groups. The non-responder rate was 11.6% inmale, and 7.4% in female. This rate was 6% in under 40 years old group,and 22.7% in 40 or older group. This difference was significant in twogroups statistically (p=0.02. The rapid immunization programme, weperformed has nearly the same success results as in standard programme.

  16. Rapid serial visual presentation design for cognition

    CERN Document Server

    Spence, Robert


    A powerful new image presentation technique has evolved over the last twenty years, and its value demonstrated through its support of many and varied common tasks. Conceptually, Rapid Serial Visual Presentation (RSVP) is basically simple, exemplified in the physical world by the rapid riffling of the pages of a book in order to locate a known image. Advances in computation and graphics processing allow RSVP to be applied flexibly and effectively to a huge variety of common tasks such as window shopping, video fast-forward and rewind, TV channel selection and product browsing. At its heart is a

  17. Rapid spectral analysis for spectral imaging. (United States)

    Jacques, Steven L; Samatham, Ravikant; Choudhury, Niloy


    Spectral imaging requires rapid analysis of spectra associated with each pixel. A rapid algorithm has been developed that uses iterative matrix inversions to solve for the absorption spectra of a tissue using a lookup table for photon pathlength based on numerical simulations. The algorithm uses tissue water content as an internal standard to specify the strength of optical scattering. An experimental example is presented on the spectroscopy of portwine stain lesions. When implemented in MATLAB, the method is ~100-fold faster than using fminsearch().


    Energy Technology Data Exchange (ETDEWEB)

    ZHAO, Y.


    An FFAG moot likely requires rapid cavity tuning. The cavity must also have a very high gradient. To satisfy both the high power and rapid tuning requirements is a big challenge. Detailed investigation of the possibility is addressed. Included are general thoughts, dual-loop and simple loop analyses, and a study of using ferrite or PIN diodes. Also proposed is a phase control scheme, which may be a better solution if the needed components can be developed. Finally, an energy analysis reveals the difficult of high power tuning.

  19. Rapid and non-rapid cycling bipolar disorder : A meta-analysis of clinical studies

    NARCIS (Netherlands)

    Kupka, RW; Luckenbaugh, DA; Post, RM; Leverich, GS; Nolen, WA


    Background: Rapid cycling, defined as 4 or more mood episodes per year, is a course specifier of bipolar disorder associated with relative treatment resistance. Several risk factors have been suggested to be associated with rapid cycling. The purpose of this meta-analysis was to compare clinical stu

  20. A rapidly enlarging cutaneous hemangioma in pregnancy

    Directory of Open Access Journals (Sweden)

    Marwan Ma’ayeh


    Full Text Available This is a case of a rapidly enlarging cutaneous pedunculated tumor on a patient’s thumb during her pregnancy. This was excised and identified as a hemangioma. A literature search identified a possible hormonal factor in causing an accelerated growth of this tumor.

  1. Utilizing Information Technology to Facilitate Rapid Acquisition (United States)


    PAGES 109 14. SUBJECT TERMS Rapid Acquisition, eCommerce , eProcurement, Information Technology, Contracting, Global Information Network...Agency. 5 eCommerce and eProcurement, and possess an adequate knowledge of information technology. D. RESEARCH QUESTIONS 1. Primary Research... eCommerce , Information Technology, and eProcurement knowledge, and government and private industry reports utilizing numerous library and Internet

  2. The Health Penalty of China's Rapid Urbanization

    NARCIS (Netherlands)

    E. Van de Poel (Ellen); O.A. O'Donnell (Owen); E.K.A. van Doorslaer (Eddy)


    textabstractRapid urbanization could have positive and negative health effects, such that the net impact on population health is not obvious. It is, however, highly pertinent to the human welfare consequences of development. This paper uses community and individual level longitudinal data from the C

  3. Rapid Energy Modeling Workflow Demonstration Project (United States)


    BIM Building Information Model BLCC building life cycle costs BPA Building Performance Analysis CAD computer assisted...utilizes information on operations, geometry, orientation, weather, and materials, generating Three-Dimensional (3D) Building Information Models ( BIM ...executed a demonstration of Rapid Energy Modeling (REM) workflows that employed building information modeling ( BIM ) approaches and

  4. High precision, rapid laser hole drilling (United States)

    Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.


    A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.

  5. Set point calculations for RAPID project

    Energy Technology Data Exchange (ETDEWEB)



    The Respond and Pump in Days (RAPID) project was initiated to pump part of the contents of tank 241-SY-101 into tank 241-SY-102. This document establishes the basis for all set points and ranges used in the RAPID project. There are 23 instrument and/or control loops utilized by the RAPID project. These range from the simple indication loop with two components to complex indication, control, and alarm loops with up to eight components. Several loops include safety class elements. This document is intended to describe the loops in full and to provide the basis for each of the element setpoints, ranges and accuracies identified in the RAPID project Master Equipment List (MEL). These values are developed in two steps. First, the base value is identified with reference to the supporting document providing that value. Second, a spreadsheet calculation is performed on each element and loop, utilizing a standard methodology described below, that takes into account known and suspected variance in output and establishes the actual setpoint used on a given element. The results of the spreadsheet are reported directly in this document.

  6. Implementing RapidArc into clinical routine

    DEFF Research Database (Denmark)

    Van Esch, Ann; Huyskens, Dominique P; Behrens, Claus F;


    With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto...

  7. Memory operations in rapid serial visual presentation

    NARCIS (Netherlands)

    Akyürek, Elkan G.; Hommel, Bernhard


    Short-term memory (STM) has often been considered to be a central resource in cognition. This study addresses its role in rapid serial visual presentation (RSVP) tasks tapping into temporal attention-the attentional blink (AB). Various STM operations are tested for their impact on performance and, i

  8. Rapid system understanding : two COBOL case studies

    NARCIS (Netherlands)

    Deursen, A. van; Kuipers, T.


    Rapid system understanding is required in the planning, feasibility assessment and cost estimating phases of a system renovation project. In this paper, we apply a number of analyses on two large legacy COBOL systems from the banking field. We describe the analyses performed, and discuss possible in

  9. Rapid Technology Assessment Framework for Land Logistics (United States)


    navigation technology) becomes dead weight; reverse logistic chain may be required to bring the equipment back • Local systems and networks will...UNCLASSIFIED UNCLASSIFIED Rapid Technology Assessment Framework for Land logistics Ksenia Ivanova and Guy Edward this document focuses on military Land logistics applications, although similar principles can be applied to other military domains

  10. A rapidly enlarging cutaneous hemangioma in pregnancy.

    LENUS (Irish Health Repository)

    Ma'ayeh, Marwan


    This is a case of a rapidly enlarging cutaneous pedunculated tumor on a patient\\'s thumb during her pregnancy. This was excised and identified as a hemangioma. A literature search identified a possible hormonal factor in causing an accelerated growth of this tumor.

  11. Rapid eye movement sleep behavior disorder

    DEFF Research Database (Denmark)

    Zoetmulder, Marielle; Jennum, Poul


    Rapid eye movement (REM) sleep behaviour disorder (RBD) is characterized by loss of REM sleep and related electromyographic atonia with marked muscular activity and dream enactment behaviour. RBD is seen in 0.5% of the population. It occurs in an idiopathic form and secondarily to medical...

  12. Rapidly solidified aluminium for optical applications

    NARCIS (Netherlands)

    Gubbels, G.P.H.; Venrooy, B.W.H. van; Bosch, A.J.; Senden, R.


    This paper present the results of a diamond turning study of a rapidly solidified aluminium 6061 alloy grade, known as RSA6061. It is shown that this small grain material can be diamond turned to smaller roughness values than standard AA6061 aluminium grades. Also, the results are nearly as good as

  13. Rapid-Cycling Bubble-Chamber, details

    CERN Multimedia


    Parts of the hydraulic expansion system of the Rapid-Cycling Bubble-Chamber (RCBC). RCBC was the largest of 3 rapid-cycling bubble-chambers (the others were LEBC and HOLEBC), used as target- and vertex-detectors within the European Hybrid Spectrometer (EHS) in the SPS North Area (EHN1). RCBC contained 250 l of liquid hydrogen and was located inside a 3 T superconducting magnet. It was designed for 30 expansions/s (100 times faster than BEBC), the system shown here allowed 50 expansions/s. RCBC operated from 1981 to 1983 for experiments NA21, NA22 and NA23 at a rate of 15 expansions/s, clocking up a total of over 4 million. In the rear, at left, is bearded Lucien Veillet; Augustin Didona is at the right. See also 8001009. The installation of the piston assembly in the RCBC chamber body is shown in the Annual Report 1980, p.65.

  14. Rapid Treatment of Rhinophyma with Powered Microdebrider

    Directory of Open Access Journals (Sweden)

    C. Faris


    Full Text Available We describe here our experience in using sinus microdebrider to rapidly debulk and sculpt the tissues in cases of rhinophyma correction. We utilized the use of the 4 mm M4 Rotatable Cutting Straight Sinus Blade on a straight Straightshot M4 Microdebrider by Medtronic at 800 rpm oscillation which is normally utilised in our sinus surgery practice. The microdebrider is straightforward to use and is already stocked in most ENT departments. It requires no additional training or cost outlay for departments that perform endoscopic sinus surgery with microdebrider. In our experience it affords the surgeon the ability to rapidly and accurately sculpt the nose to an excellent aesthetic result. We feel it is a more precise tool than cold steel or Bovie cautery, quicker than CO2 laser techniques, and avoids the aerosol of dermabrasion. No complications occurred in our series, and all patients rated their cosmetic outcome as good to excellent.

  15. [Rapid analysis of added ingredients in heroin]. (United States)

    Wang, Ji-fen; Yu, Jing; Guo, Xin; Sun, Xing-long; Wang, Ding-fang


    The method of rapid analysis of added ingredients in heroin was studied in the present paper. Adding sucrose, fructose, glucose, starch, caffeine and phenacetin to heroin with a certain percentage, the changes in the infrared spectrum with the concentration of heroin increasing and the detection limit of the additives were determined. Whether or not heroin can be detected in the sample with high concentration of added ingredients was studied using Raman spectroscopy. Similarly, in high purity of heroin, whether or not Raman spectroscopy can detect the added ingredients was tested. Through systematic experiments, the results showed that: using infrared spectroscopy and Raman spectroscopy to test the added ingredients of heroin is a rapid and effective method. Each has both advantages and disadvantages. We should select the appropriate method according to the actual cases.

  16. Low Gravity Rapid Thermal Analysis of Glass (United States)

    Tucker, Dennis S.; Ethridge, Edwin C.; Smith, Guy A.


    It has been observed by two research groups that ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass crystallization is suppressed in microgravity. The mechanism for this phenomenon is unknown at the present time. In order to better understand the mechanism, an experiment was performed on NASA's KC135 reduced gravity aircraft to obtain quantitative crystallization data. An apparatus was designed and constructed for performing rapid thermal analysis of milligram quantities of ZBLAN glass. The apparatus employs an ellipsoidal furnace allowing for rapid heating and cooling. Using this apparatus nucleation and crystallization kinetic data was obtained leading to the construction of time-temperature-transformation curves for ZBLAN in microgravity and unit gravity.

  17. Reconsidering Rapid Qubit Purification by Feedback

    CERN Document Server

    Wiseman, H M


    This paper reconsiders the properties of a scheme for the rapid purification of the quantum state of a qubit, proposed recently in Jacobs 2003 Phys. Rev. A67 030301(R). The qubit starts in a completely mixed state, and information is obtained by a continuous measurement. Jacobs' rapid purification protocol uses Hamiltonian feedback control to maximise the average purity of the qubit for a given time, with a factor of two increase in the purification rate over the no-feedback protocol. However, by re-examining the latter approach, we show that it mininises the average time taken for a qubit to reach a given purity. In fact, the average time taken for the no-feedback protocol beats that for Jacobs' protocol by a factor of two. We discuss how this is compatible with Jacobs' result, and the usefulness of the different approaches.

  18. Surgically assisted rapid maxillary expansion in adults. (United States)

    Pogrel, M A; Kaban, L B; Vargervik, K; Baumrind, S


    Twelve adults with maxillary width discrepancy of greater than 5 mm were treated by surgically assisted rapid maxillary expansion. The procedure consisted of bilateral zygomatic buttress and midpalatal osteotomies combined with the use of a tooth-borne orthopedic device postoperatively. Mean palatal expansion of 7.5 mm (range of 6 to 13 mm), measured in the first molar region, was achieved within 3 weeks in all patients. Expansion remained stable during the 12-month study period, with a mean relapse for the entire group of 0.88 +/- 0.48 mm. Morbidity was limited to mild postoperative discomfort. The results of this preliminary study indicated that surgically assisted rapid maxillary expansion is a safe, simple, and reliable procedure for achieving a permanent increase in skeletal maxillary width in adults. Further study is necessary to document the three-dimensional movements of the maxillary segments and long-term stability of the skeletal and dental changes.

  19. Regional adaptive delaminating algorithm for rapid prototyping

    Institute of Scientific and Technical Information of China (English)

    CAI Daosheng; SHI Yusheng; HUANG Shuhuai


    With the development of rapid prototyping (RP) technology, the contradiction between fabricating speed and precision becomes more and more acute. In order to solve the contradiction, a regional effective adaptive delaminating algorithm is proposed in this paper. It is different from the traditional method that the regional adaptive delaminating method divides slicing contours into several regions and adaptively delaminates in respective region only according to the contours information. Namely, this method can not only adaptively delaminate at different height of CAD model but also adaptively delaminate different regions in one slicing layer. Furthermore, because the two-dimensional contour data adopted in this method are necessary for rapid prototyping system, this regional effective adaptive delaminating method is suitable for all RP systems. A comparative study is used to analyze the effectiveness of this method, which can demonstrate that this method can increase the fabricating speed and reduce the running cost under the condition of ensuring fabricating precision.

  20. Rapid eye movement sleep in breath holders. (United States)

    Kohyama, J; Hasegawa, T; Shimohira, M; Fukumizu, M; Iwakawa, Y


    One-night polysomnography was performed on seven subjects suffering from breath-holding spells, including one whose death was suggested to be a consequence of a breath-holding spell. The fatal case showed no rapid eye movements (REMs) during REM sleep, although he exhibited REMs during wakefulness. The average numbers of both REMs and bursts of REMs in REM sleep in the other six breath holders were significantly lower than those in age-matched controls. The breath holders showed no airway obstruction, desaturation, or sleep fragmentation. Since the rapid ocular activity in REM sleep is generated in the brain stem, we hypothesized that a functional brainstem disturbance is involved in the occurrence of breath-holding spells.

  1. Rapid parapatric speciation on holey adaptive landscapes

    CERN Document Server

    Gavrilets, S; Vose, M D; Gavrilets, Sergey; Li, Hai; Vose, Michael D.


    A classical view of speciation is that reproductive isolation arises as a by-product of genetic divergence. Here, individual-based simulations are used to evaluate whether the mechanisms implied by this view may result in rapid speciation if the only source of genetic divergence are mutation and random genetic drift. Distinctive features of the simulations are the consideration of the complete process of speciation (from initiation until completion), and of a large number of loci, which was only one order of magnitude smaller than that of bacteria. It is demonstrated that rapid speciation on the time scale of hundreds of generations is plausible without the need for extreme founder events, complete geographic isolation, the existence of distinct adaptive peaks or selection for local adaptation. The plausibility of speciation is enhanced by population subdivision. Simultaneous emergence of more than two new species from a subdivided population is highly probable. Numerical examples relevant to the theory of ce...

  2. New Methodology for Rapid Seismic Risk Assessment (United States)

    Melikyan, A. E.; Balassanian, S. Y.


    Seismic risk is growing worldwide and is, increasingly, a problem of developing countries. Along with growing urbanization future earthquakes will have more disastrous social and economic consequences. Seismic risk assessment and reduction are important goals for each country located in seismically active zone. For Armenia these goals are of primary importance because the results of studies carried out by Armenian NSSP for assessment of the losses caused by various types of disasters in Armenia had shown that earthquakes are the most disastrous hazard for Armenia. The strategy for seismic risk reduction in 1999 was adopted by the Government of Armenia as a high priority state program. The world experience demonstrates that for efficient response the rapid assessment of seismic losses is necessary. There are several state-of-the-art approaches for seismic risk assessment (Radius, Hazus, etc.). All of them required large amount of various input data, which is impossible to collect in many developing countries, in particular in Armenia. Taking into account this very serious problem existing for developing countries, as well as rapid seismic risk assessment need immediately after strong earthquake the author undertake the attempt to contribute into a new approach for rapid seismic risk assessment under the supervision of Prof. S. Balassanian. The analysis of numerous factors influencing seismic risk in Armenia shows that the following elements contribute most significantly to the possible losses: seismic hazard; density of population; vulnerability of structures. Proposed approach for rapid seismic risk assessment based on these three factors has been tested for several seismic events. These tests have shown that such approach might represent from 80 to 90 percent of real losses.

  3. Rapid and highly fieldable viral diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    McKnight, Timothy E.


    The present invention relates to a rapid, highly fieldable, nearly reagentless diagnostic to identify active RNA viral replication in a live, infected cells, and more particularly in leukocytes and tissue samples (including biopsies and nasal swabs) using an array of a plurality of vertically-aligned nanostructures that impale the cells and introduce a DNA reporter construct that is expressed and amplified in the presence of active viral replication.

  4. Rapid Advancement of Immunology Study in China

    Institute of Scientific and Technical Information of China (English)


    The world-renowned Cell Press recently released a new informational supplement--Spotlight on Chi- na-to introduce the rapid developments in the basic and clinical researches in immunology in China. The electronic version of the supplement can be viewed or downloaded for free on the website of the Cell Press (http://www. cell. com/spotlightonchina), and the hard copy will be published along with the new issue of Immunity in November.

  5. Rapid Prototyping Technology of Tissue Engineering Scaffold

    Institute of Scientific and Technical Information of China (English)



    In the modern medicine field, the transplant of organ and tissue is a big problem due to serious shortage of donor organ. Artificial organ and tissue is one of solutions. With the development of science, various tissue manufacture techniques emerged. Hereinto, due to its versatility both in materials and structure, rapid prototyping technology has become one of the important methods for tissue engineering scaffold fabrication in this field.

  6. Rapid complexometric analysis of brass with CTDA. (United States)

    Goetz, C A; Loomis, T C


    A method for the analysis of brass is presented. The lead, iron, nickel and zinc components are determined titrimetrically with the complexing agent CDTA (disodium dihydrogen 1,2-diaminocyclohexane N,N,N',N'-tetraacetate [also known as HexaVer]). The copper and the tin are weighed as metallic copper and as stannic oxide. The method is more rapid and convenient, especially for routine analysis, than the all-gravimetric procedure and it provides at least equal accuracy and precision.

  7. Rapid Separation of Fission Product 141La

    Institute of Scientific and Technical Information of China (English)

    XIA; Wen; YE; Hong-sheng; LIN; Min; CHEN; Ke-sheng; XU; Li-jun; ZHANG; Wei-dong; CHEN; Yi-zhen


    141La was separated and purified from fission products in this work for physical measurements aimed at improving the accuracy of its decay parameters.As the impact of 142La and other fission products,cesium(141Cs,142Cs included)was rapid separated from the fission products,141Cs and 142Ba separation was prepared after a cooling time about 25 s when 142Cs decays to daughter 142Ba,141La purification then

  8. Rapidity gaps between jets at D0

    Energy Technology Data Exchange (ETDEWEB)

    Abachi, S.; D0 Collaboration


    Results are presented from an analysis of the particle multiplicity distribution between high transverse energy jets produced at the Fermilab Tevatron p{bar p} Collider at {radical}s = 1.8 Tev. Using the D0 detector, we examine the particle multiplicity distribution between the two highest transverse energy jets. For events with large rapidity separation, we observed a significant excess of events at low tagged-particle multiplicity which is consistent with a strongly interacting color-singlet exchange process.

  9. Chinese Advanced Materials Industry Grows Rapidly

    Institute of Scientific and Technical Information of China (English)


    Revealed from "2005 China Annual Market Conference of Advanced Materials", the advanced materials industry in China grows rapidly, with market scale RMB ¥18.01 billion, increasing 27.7% over last year. By now, total 79 production bases of advanced materials have been built in China and constellation effect of rare earth industry has emerged. Beijing, Shenzhen and Shanghai have been developed into

  10. Rapid Output Growth of Special Acrylic Esters

    Institute of Scientific and Technical Information of China (English)

    Wang Lianzhi


    @@ Acrylic esters are usually classified into general-purpose varieties and special varieties. The production and application of general-purpose varieties is already quite matured in the world and their output growth tends to be flat. Owing to the development of coatings, electronics, automobiles,textiles, printing and construction sectors, especially the application of radiation curing technology in various sectors, special acrylic esters have developed rapidly.

  11. Rapidity correlation structure in nuclear collisions (United States)

    Gavin, Sean; Moschelli, George; Zin, Christopher


    We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time τπ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity ν =η /s T . We formulate methods for computing these correlations using second-order dissipative hydrodynamics with noise. Current data are consistent with τπ/ν ˜10 , but targeted measurements can improve this precision.

  12. Robotic milling for rapid ceramic pototyping

    Institute of Scientific and Technical Information of China (English)

    HAN Guang-chao; ZHANG Hai-ou; WANG Gui-lan


    Robotic milling is a developing method for rapidly producing prototypes and parts, but the application is limited for materials such as wax, wood, plastic and light metal, etc. The reason for this is because of the robotic weak rigidity. In this paper, a method of robotic milling for ceramic prototyping is developed, one that has been successfully applied in a new rapid hard tooling technology-Direct Prototype Spray Tooling[1]. At first, the appropriate ceramic materials mixed with metal powder are confirmed for the robotic milling and the following plasma spraying process. Then the 6 - DOF robotic milling paths are extracted from the NC code and transformed into the robotic JBI type file, the NC code generated through the general CAD/CAM software such as UG -NX.Finally, the robotic milling characteristics such as moving path accuracy and milling force are tested to find the best milling parameters and to ensure the executable, accurate and efficient ceramic prototype milling technology.The development of this method not only broadens the robotic milling material range but also extends the rapid prototyping fields. It can also be used for producing ceramic parts that are difficult to machine.

  13. Rapid sequence intubation in the neonate. (United States)

    Bottor, Lottie T


    Rapid sequence intubation (RSI) is premedication prior to intubation that includes atropine, a sedative, and a neuromuscular blockage. Rapid sequence intubation is infrequently performed in neonates despite evidence that it is safe and effective. Neonates that experience endotracheal intubation often display apnea and cardiac arrhythmias, decreased or obstructed nasal airflow, increased systolic blood pressure, and decreased heart rate and transcutaneous oxygen tension. Infants can also experience increased anterior fontanel pressure, which can place them at greater risk for intraventricular hemorrhage. Rapid sequence intubation has been shown to facilitate better intubation conditions including no movement from the infant and better visualization of the airway. Infants receiving RSI were successfully intubated twice as fast as infants who were not premedicated. Infants with premedication also had fewer changes in baseline heart rate. Neonatal RSI can be easily and safely performed in the neonate. Knowledge and skill allow for the best conditions when intubating the infant. Future research must focus on the best combination of medications for RSI in the neonate.

  14. MSFC Electrostatic Levitator (ESL) Rapid Quench System (United States)

    SanSoucie, Michael P.; Craven, Paul D.; Rogers, Jan R.


    The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) Laboratory is a unique facility for investigators studying high-temperature materials. The laboratory boasts two levitators in which samples can be levitated, heated, melted, undercooled, and resolidified, all without the interference of a container or data-gathering instrument. The ESL main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy. Thereby allowing rapid quenching of undercooled liquid metals. Up to 8 quench vessels can be loaded into the quench wheel, which is indexed with LabVIEW control software. This allows up to 8 samples to be rapidly quenched before having to open the chamber. The system has been tested successfully on several zirconium samples. Future work will be done with other materials using different quench mediums. Microstructural analysis will also be done on successfully quench samples.

  15. Rapid Prototyping and its Application in Dentistry

    Directory of Open Access Journals (Sweden)

    V. N. V. Madhav


    Full Text Available Medical implants and biological models have three main characteristics: low volume, complex shape, and can be customized. These characteristics suit very well with Rapid Prototyping (RP and Rapid Manufacturing (RM processes. RP/RM processes are fabricated part layer- by-layer until complete shape finished from 3D model. Biocompatible materials, such as Titanium and Titanium alloy, Zirconium, Cobalt Chromium, PEEK, etc, are used for fabrication process. Reverse Engineering (RE technology greatly affects RP/RM processes. RE is used to capture or scan image of the limb, cranium, tooth, and other biological objects. Three common methods to get the image are 3D laser scanning, Computer Tomography (CT, and Magnetic Resonance Imaging (MRI. Main RP/RM techniques used in Dentistry are Stereotype Lithography Apparatus (SLA, Fused Deposition Modeling (FDM, Selective Laser Sintering (SLS, and ink jet printing. This article reviews the changing scenario of technology in dentistry with special emphasis on Rapid Prototyping and its various applications in Dentistry.

  16. Management of Infections with Rapidly Growing

    Directory of Open Access Journals (Sweden)

    Jong Hwan Kim


    Full Text Available Background Infection caused by rapidly growing mycobacteria (RGM is not uncommon, andthe prevalence of RGM infection has been increasing. Clinical diagnosis is difficult becausethere are no characteristic clinical features. There is also no standard antibiotic regimenfor treating RGM infection. A small series of patients with RGM infections was studied toexamine their treatments and outcomes.Methods A total of 5 patients who had developed postoperative infections from January2009 to December 2010 were retrospectively reviewed. Patients were initially screened using amycobacteria rapid screening test (polymerase chain reaction [PCR]-reverse blot hybridizationassay. To confirm mycobacterial infection, specimens were cultured for nontuberculousmycobacteria and analyzed by 16 S ribosomal RNA and rpoB gene PCR.Results The patients were treated with intravenous antibiotics during hospitalization,and oral antibiotics were administered after discharge. The mean duration of follow-upwas 9 months, and all patients were completely cured of infection with a regimen of acombination of antibiotics plus surgical treatment. Although none of the patients developedrecurrence, there were complications at the site of infection, including hypertrophic scarring,pigmentation, and disfigurement.Conclusions Combination antibiotic therapy plus drainage of surgical abscesses appeared tobe effective for the RGM infections seen in our patients. Although neither the exact dosagenor a standardized regimen has been firmly established, we propose that our treatment canprovide an option for the management of rapidly growing mycobacterial infection.

  17. Analysis of Rapid Acquisition Processes to Fulfill Future Urgent Needs (United States)


    minimally expanded the language regarding rapid acquisition process to include “Evolutionary acquisition is the preferred DOD strategy for rapid...requirements for rapid acquisition of ACAT I & IA programs. Second, identify how DOD will fund rapid acquisition programs. Third , identify who in DOD will...directives is challenging but necessary. 40 Third , organizational structure must remain in place to support the rapid acquisition process, we must


    Institute of Scientific and Technical Information of China (English)

    李天文; 孙长贵; 毛在砂; 陈家镛



  19. Intraperitoneal Glucose Sensing is Sometimes Surprisingly Rapid

    Directory of Open Access Journals (Sweden)

    Anders Lyngvi Fougner


    Full Text Available Rapid, accurate and robust glucose measurements are needed to make a safe artificial pancreas for the treatment of diabetes mellitus type 1 and 2. The present gold standard of continuous glucose sensing, subcutaneous (SC glucose sensing, has been claimed to have slow response and poor robustness towards local tissue changes such as mechanical pressure, temperature changes, etc. The present study aimed at quantifying glucose dynamics from central circulation to intraperitoneal (IP sensor sites, as an alternative to the SC location. Intraarterial (IA and IP sensors were tested in three anaesthetized non-diabetic pigs during experiments with intravenous infusion of glucose boluses, enforcing rapid glucose level excursions in the range 70--360 mg/dL (approximately 3.8--20 mmol/L. Optical interferometric sensors were used for IA and IP measurements. A first-order dynamic model with time delay was fitted to the data after compensating for sensor dynamics. Additionally, off-the-shelf Medtronic Enlite sensors were used for illustration of SC glucose sensing. The time delay in glucose excursions from central circulation (IA to IP sensor location was found to be in the range 0--26 s (median: 8.5 s, mean: 9.7 s, SD 9.5 s, and the time constant was found to be 0.5--10.2 min (median: 4.8 min, mean: 4.7 min, SD 2.9 min. IP glucose sensing sites have a substantially faster and more distinctive response than SC sites when sensor dynamics is ignored, and the peritoneal fluid reacts even faster to changes in intravascular glucose levels than reported in previous animal studies. This study may provide a benchmark for future, rapid IP glucose sensors.

  20. Rapid response manufacturing (RRM). Final CRADA report

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)


    US industry is fighting to maintain its competitive edge in the global market place. Markets fluctuate rapidly. Companies have to be able to respond quickly with improved, high quality, cost efficient products. Because companies and their suppliers are geographically distributed, rapid product realization is dependent on the development of a secure integrated concurrent engineering environment operating across multiple business entities. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies implemented in a secure environment. This documents the work done under this CRADA to develop capabilities, which permit the effective application, incorporation, and use of advanced technologies in a secure environment to facilitate the product realization process. Lockheed Martin Energy Systems (LMES), through a CRADA with the National Center for Manufacturing Sciences (NCMS), worked within a consortium of major industrial firms--Ford, General Motors, Texas Instruments, United Technologies, and Eastman Kodak--and several small suppliers of advanced manufacturing technology--MacNeal-Schwendler Corp., Teknowledge Corp., Cimplex Corp., Concentra, Spatial Technology, and Structural Dynamics Research Corp. (SDRC)--to create infrastructure to support the development and implementation of secure engineering environments for Rapid Response Manufacturing. The major accomplishment achieved under this CRADA was the demonstration of a prototypical implementation of a broad-based generic framework for automating and integrating the design-to-manufacturing activities associated with machined parts in a secure NWC compliant environment. Specifically, methods needed to permit the effective application, incorporation, and use of advanced technologies in a secure environment to facilitate the product realization process were developed and demonstrated. An important aspect of this demonstration was

  1. Microfluidic gene arrays for rapid genomic profiling (United States)

    West, Jay A.; Hukari, Kyle W.; Hux, Gary A.; Shepodd, Timothy J.


    Genomic analysis tools have recently become an indispensable tool for the evaluation of gene expression in a variety of experiment protocols. Two of the main drawbacks to this technology are the labor and time intensive process for sample preparation and the relatively long times required for target/probe hybridization. In order to overcome these two technological barriers we have developed a microfluidic chip to perform on chip sample purification and labeling, integrated with a high density genearray. Sample purification was performed using a porous polymer monolithic material functionalized with an oligo dT nucleotide sequence for the isolation of high purity mRNA. These purified mRNA"s can then rapidly labeled using a covalent fluorescent molecule which forms a selective covalent bond at the N7 position of guanine residues. These labeled mRNA"s can then released from the polymer monolith to allow for direct hybridization with oligonucletide probes deposited in microfluidic channel. To allow for rapid target/probe hybridization high density microarray were printed in microchannels. The channels can accommodate array densities as high as 4000 probes. When oligonucleotide deposition is complete, these channels are sealed using a polymer film which forms a pressure tight seal to allow sample reagent flow to the arrayed probes. This process will allow for real time target to probe hybridization monitoring using a top mounted CCD fiber bundle combination. Using this process we have been able to perform a multi-step sample preparation to labeled target/probe hybridization in less than 30 minutes. These results demonstrate the capability to perform rapid genomic screening on a high density microfluidic microarray of oligonucleotides.

  2. Rapid Tooling Technique Based on Stereolithograph Prototype

    Institute of Scientific and Technical Information of China (English)

    丁浩; 狄平; 顾伟生; 朱世根


    Rapid tooling technique based on the sterelithograph prototype is investigated. The epoxy tooling technological process was elucidated. It is analyzed in detail that the epoxy resin formula is easy to cast, curing process, and release agents. The transitional plaster model is also proposed. The mold to encrust mutual.inductors with epoxy and mold to inject plastic soapboxes was made with the technique The tooling needs very little time and cost, for the process is only to achieve the nice replica of the prototype. It is benefit for the trial and small batch of production.

  3. Post liposuction infections by rapidly growing mycobacteria. (United States)

    Zosso, Caroline; Lienhard, Reto; Siegrist, Hans H; Malinverni, Raffaele; Clerc, Olivier


    Rapidly growing mycobacteria (RGM) are recognized agents of surgical site infections. Recently, RGM skin and soft tissue infections have been increasingly reported. As symptoms, clinical signs and disease latency remain non-specific and microbiological detection requires targeted growth media, RGM diagnosis remains challenging for clinicians. Appropriate management is often delayed due to lack of awareness of these infections. RGM infections after plastic surgery have also been described in the setting of interventions performed in developing countries, a growing phenomenon commonly known as medical tourism. We describe a case of Mycobacterium chelonae/abscessus infection following liposuction and liposculpture procedures performed in the Dominican Republic and review the literature on this subject.

  4. Rapidly Progressive Spontaneous Spinal Epidural Abscess

    Directory of Open Access Journals (Sweden)

    Abdurrahman Aycan


    Full Text Available Spinal epidural abscess (SEA is a rare disease which is often rapidly progressive. Delayed diagnosis of SEA may lead to serious complications and the clinical findings of SEA are generally nonspecific. Paraspinal abscess should be considered in the presence of local low back tenderness, redness, and pain with fever, particularly in children. In case of delayed diagnosis and treatment, SEA may spread to the epidural space and may cause neurological deficits. Magnetic resonance imaging (MRI remains the method of choice in the diagnosis of SEA. Treatment of SEA often consists of both medical and surgical therapy including drainage with percutaneous entry, corpectomy, and instrumentation.

  5. Rapidly Progressive Spontaneous Spinal Epidural Abscess. (United States)

    Aycan, Abdurrahman; Aktas, Ozgür Yusuf; Guzey, Feyza Karagoz; Tufan, Azmi; Isler, Cihan; Aycan, Nur; Gulsen, İsmail; Arslan, Harun


    Spinal epidural abscess (SEA) is a rare disease which is often rapidly progressive. Delayed diagnosis of SEA may lead to serious complications and the clinical findings of SEA are generally nonspecific. Paraspinal abscess should be considered in the presence of local low back tenderness, redness, and pain with fever, particularly in children. In case of delayed diagnosis and treatment, SEA may spread to the epidural space and may cause neurological deficits. Magnetic resonance imaging (MRI) remains the method of choice in the diagnosis of SEA. Treatment of SEA often consists of both medical and surgical therapy including drainage with percutaneous entry, corpectomy, and instrumentation.

  6. Rapid Prototyping: Technologies, Materials and Advances

    Directory of Open Access Journals (Sweden)

    Dudek P.


    Full Text Available In the context of product development, the term rapid prototyping (RP is widely used to describe technologies which create physical prototypes directly from digital data. Recently, this technology has become one of the fastest-growing methods of manufacturing parts. The paper provides brief notes on the creation of composites using RP methods, such as stereolithography, selective laser sintering or melting, laminated object modelling, fused deposition modelling or three-dimensional printing. The emphasis of this work is on the methodology of composite fabrication and the variety of materials used in these technologies.

  7. Rapid Drop Dynamics During Superhydrophobic Condensation (United States)

    Zhang, Xiaodong; Boreyko, Jonathan; Chen, Chuan-Hua


    Rapid drop motion is observed on superhydrophobic surfaces during condensation; condensate drops with diameter of order 10 μm can move at above 100G and 0.1 m/s. When water vapor condenses on a horizontal superhydrophobic surface, condensate drops move in a seemingly random direction. The observed motion is attributed to the energy released through coalescence of neighboring condensate drops. A scaling analysis captured the initial acceleration and terminal velocity. Our work is a step forward in understanding the dynamics of superhydrophobic condensation occurring in both natural water-repellant plants and engineered dropwise condensers.

  8. Plant MAPK cascades: Just rapid signaling modules?

    KAUST Repository

    Boudsocq, Marie


    © 2015 Taylor & Francis Group, LLC. Abscisic acid (ABA) is a major phytohormone mediating important stress-related processes. We recently unveiled an ABA-activated MAPK signaling module constituted of MAP3K17/18-MKK3-MPK1/2/7/14. Unlike classical rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests that MAPKs can regulate both early and longterm plant stress responses.

  9. Rapid thermal processing science and technology

    CERN Document Server

    Fair, Richard B


    This is the first definitive book on rapid thermal processing (RTP), an essential namufacturing technology for single-wafer processing in highly controlled environments. Written and edited by nine experts in the field, this book covers a range of topics for academics and engineers alike, moving from basic theory to advanced technology for wafer manufacturing. The book also provides new information on the suitability or RTP for thin film deposition, junction formation, silicides, epitaxy, and in situ processing. Complete discussions on equipment designs and comparisons between RTP and other

  10. Rapid Prototyping: State of the Art (United States)


    Consumer products 25.5% Aerospace 8.6% Motor vehicles 23.8% Government/ military 6.9% Other 8.7% Source: Wohlers Report 2002 Figure 6. Industrial... Wohlers Report 2002 Figure 7. Purchases and Installations of RP Systems by Country 7 1.4 Number of Models Being Produced Despite a decline in overall...1.5 2 2.5 3 3.5 4 1998 1999 2000 2001 Source: Wohlers Report 2002 Figure 8. Number of RP Models Produced 1.5 Rapid Tooling Methods, processes, and

  11. Smith Predictor Based Robust Rapid Tracking Controller

    Institute of Scientific and Technical Information of China (English)

    LIU Hongbin; HU Dejin


    Precise model is hard to get in real application, a Smith predictor based robust rapid tracking controller for inaccurate model is proposed. Zero phase error feedforward controller which increases system closed-loop dynamics and disturbance observer based Smith feedback control which diminishes model hysteresis and improves stability are integrated. This method is applied in the noncircular machining with piezoelectric ceramic driver. The simulation and experiment show that the performance robustness and stability are well balanced in bandwidth about 200 Hz. The controller can decrease system hysteresis and get good tracking performance for predefined square-wave input signal.

  12. Simulation Model of Bus Rapid Transit

    Directory of Open Access Journals (Sweden)

    Gunawan Fergyanto E.


    Full Text Available Bus rapid transit system is modern solution for mass transportation system. The system, in comparison to the rail-based transportation system, is significantly cheaper and requires shorter development time, but lower performance. The BRT system performance strongly depends on variables related to station design and infrastructure. A numerical model offers an effective and efficient means to evaluate the system performance. This article offers a detailed numerical model on the basis of the discrete-event approach and demonstrates its application.

  13. CFD Script for Rapid TPS Damage Assessment (United States)

    McCloud, Peter


    This grid generation script creates unstructured CFD grids for rapid thermal protection system (TPS) damage aeroheating assessments. The existing manual solution is cumbersome, open to errors, and slow. The invention takes a large-scale geometry grid and its large-scale CFD solution, and creates a unstructured patch grid that models the TPS damage. The flow field boundary condition for the patch grid is then interpolated from the large-scale CFD solution. It speeds up the generation of CFD grids and solutions in the modeling of TPS damages and their aeroheating assessment. This process was successfully utilized during STS-134.

  14. An Unusual Case of Rapidly Progressive Hyperbilirubinemia

    Directory of Open Access Journals (Sweden)

    Kimberly M. Thornton


    Full Text Available We present an unusual case of hyperbilirubinemia with rapid early progression leading to bilirubin encephalopathy in a term neonate. Despite early recognition and intervention, the total serum bilirubin reached a maximum level of 39 mg/dL at 32 hours of life. Prior to an emergent exchange transfusion, the patient’s diagnostic evaluation was significant for Coombs-negative microangiopathic hemolytic anemia and thrombocytopenia. Further testing revealed a deficiency of ADAMTS13 protein, or von Willebrand factor-cleaving protease, a finding diagnostic of congenital thrombotic thrombocytopenic purpura, or Upshaw-Schulman syndrome. This rare disease is often misdiagnosed, especially in the newborn period.

  15. Rapid Response Manufacturing (RRM). Final CRADA report

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)


    A major accomplishment of the Rapid Response Manufacturing (RRM) project was the development of a broad-based generic framework for automating and integrating the design-to-manufacturing activities associated with machined part products. Key components of the framework are a manufacturing model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering working environment, knowledge-based software systems for design, process planning, and manufacturing and new production technologies for making products directly from design application software.

  16. Rapid turnover of mitochondrial uncoupling protein 3



    UCP3 (uncoupling protein 3) and its homologues UCP2 and UCP1 are regulators of mitochondrial function. UCP2 is known to have a short half-life of approx. 1 h, owing to its rapid degradation by the cytosolic 26S proteasome, whereas UCP1 is turned over much more slowly by mitochondrial autophagy. In the present study we investigate whether UCP3 also has a short half-life, and whether the proteasome is involved inUCP3 degradation. UCP3 half-life was examined in the mouse C2C12 myoblast cell line...

  17. The rapid disability rating scale-2. (United States)

    Linn, M W; Linn, B S


    A revised version of the Rapid Disability Rating Scale (RDRS-2) is presented. Item definitions have been sharpened and directions expanded to indicate that ratings are based upon the patient's performance in regard to behavior, and that prosthesis normally used by the patient should be included in the assessment. Three items have been added to increase the breadth of the scale. Response items have been changed from three-point to four-point ratings in order to increase group discrimination amd make the scale more sensitive to changes in treatment. The new appraisals of reliability, factor structure, and validity are reported, along with the potential uses of the scale.

  18. Rapid Development of China's Offshore Oil Industry

    Institute of Scientific and Technical Information of China (English)

    Zhang Haimin


    @@ Founded on February 15, 1982, China National Offshore Oil Corporation (CNOOC) has experienced two decades of rapid development, in which the annual offshore oil production rose dramatically to 23.13 million tons in 2001 from 90,000 tons in 1982while the total assets jumped to 72 billion yuan from 2.8 billion yuan, but the total employees dropped to 21,000 people from 30,000. This offshore oil giant generated a profit of 9.2 billion yuan in 2001 and turned over 4 billion yuan in taxes to the State with the crude production cost lowered to US$9 per barrel.

  19. Crowdsourced Translation for Rapid Internationalization in Cyberspace

    DEFF Research Database (Denmark)

    Tran, Yen; Yonatany, Moshe; Mahnke, Volker


    This paper explores how Facebook effectively used crowdsourced translation to accelerate its rapid internationalization. We apply the learning perspective of internationalization theory to unpack what the firm learned in order to mobilize crowd-based knowledge to facilitate internationalization...... in the virtual context, and how it did so. Increasingly, global activities are conducted in virtual space and virtual markets and thus the paper offers insights into successful expansion in this new terrain. The findings highlight two key points: (1) the firm used cognitive/explicit learning to acquire external...

  20. Chaotic Maps Dynamics, Fractals, and Rapid Fluctuations

    CERN Document Server

    Chen, Goong


    This book consists of lecture notes for a semester-long introductory graduate course on dynamical systems and chaos taught by the authors at Texas A&M University and Zhongshan University, China. There are ten chapters in the main body of the book, covering an elementary theory of chaotic maps in finite-dimensional spaces. The topics include one-dimensional dynamical systems (interval maps), bifurcations, general topological, symbolic dynamical systems, fractals and a class of infinite-dimensional dynamical systems which are induced by interval maps, plus rapid fluctuations of chaotic maps as a

  1. A rapid diagnostic test for schistosomiasis mansoni

    Directory of Open Access Journals (Sweden)

    Clelia Christina Mello-Silva


    Full Text Available This article presents an improvement to the Kato-Katz (KK method, making it faster and more efficient for the visualisation of fertile eggs in stool samples. This modified KK method uses sodium acetate formalin as a fixative and reveals the intensity of infection in less than 1 h, reducing the diagnostic time without increasing the cost. This modified method may contribute to future epidemiological studies in both hospitals and the field due to its rapid and precise diagnostic, which allow for immediate treatment.

  2. Rapidly solidified titanium alloys by melt overflow (United States)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III


    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  3. Light curves from rapidly rotating neutron stars

    CERN Document Server

    Numata, Kazutoshi


    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitudes to disturb the spot. For a $l'=m$ core $r$-mode, the oscillation frequency $\\omega\\approx2m\\Omega/[l'(l'+1)]$ defined in the co-rotating frame of the star will be detected by a distant observer, where $l'$ and $m$ are respectively the spherical harmonic degree and the azimuthal wave number of the mode, and $\\Omega$ is the spin frequency of the star. In a linear theory of oscillation, using a parameter $A$ we parametrize the mode amplitudes such that ${\\rm max}\\left(|\\xi_\\theta|,|\\xi_\\phi|\\right)/R=A$ at the surface, w...

  4. Ultra-Rapid Vision in Birds.

    Directory of Open Access Journals (Sweden)

    Jannika E Boström

    Full Text Available Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively, which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey.

  5. Rapid neural discrimination of communicative gestures. (United States)

    Redcay, Elizabeth; Carlson, Thomas A


    Humans are biased toward social interaction. Behaviorally, this bias is evident in the rapid effects that self-relevant communicative signals have on attention and perceptual systems. The processing of communicative cues recruits a wide network of brain regions, including mentalizing systems. Relatively less work, however, has examined the timing of the processing of self-relevant communicative cues. In the present study, we used multivariate pattern analysis (decoding) approach to the analysis of magnetoencephalography (MEG) to study the processing dynamics of social-communicative actions. Twenty-four participants viewed images of a woman performing actions that varied on a continuum of communicative factors including self-relevance (to the participant) and emotional valence, while their brain activity was recorded using MEG. Controlling for low-level visual factors, we found early discrimination of emotional valence (70 ms) and self-relevant communicative signals (100 ms). These data offer neural support for the robust and rapid effects of self-relevant communicative cues on behavior.

  6. Rapid neural adaptation to sound level statistics. (United States)

    Dean, Isabel; Robinson, Ben L; Harper, Nicol S; McAlpine, David


    Auditory neurons must represent accurately a wide range of sound levels using firing rates that vary over a far narrower range of levels. Recently, we demonstrated that this "dynamic range problem" is lessened by neural adaptation, whereby neurons adjust their input-output functions for sound level according to the prevailing distribution of levels. These adjustments in input-output functions increase the accuracy with which levels around those occurring most commonly are coded by the neural population. Here, we examine how quickly this adaptation occurs. We recorded from single neurons in the auditory midbrain during a stimulus that switched repeatedly between two distributions of sound levels differing in mean level. The high-resolution analysis afforded by this stimulus showed that a prominent component of the adaptation occurs rapidly, with an average time constant across neurons of 160 ms after an increase in mean level, much faster than our previous experiments were able to assess. This time course appears to be independent of both the timescale over which sound levels varied and that over which sound level distributions varied, but is related to neural characteristic frequency. We find that adaptation to an increase in mean level occurs more rapidly than to a decrease. Finally, we observe an additional, slow adaptation in some neurons, which occurs over a timescale of tens of seconds. Our findings provide constraints in the search for mechanisms underlying adaptation to sound level. They also have functional implications for the role of adaptation in the representation of natural sounds.


    Relvas, Carlos; Reis, Joana; Potes, José Alberto Caeiro; Fonseca, Fernando Manuel Ferreira; Simões, José Antonio Oliveira


    This study, aimed the development of a methodology for rapid manufacture of orthopedic implants simultaneously with the surgical intervention, considering two potential applications in the fields of orthopedics: the manufacture of anatomically adapted implants and implants for bone loss replacement. This work innovation consists on the capitation of the in situ geometry of the implant by direct capture of the shape using an elastomeric material (polyvinylsiloxane) which allows fine detail and great accuracy of the geometry. After scanning the elastomeric specimen, the implant is obtained by machining using a CNC milling machine programmed with a dedicated CAD/CAM system. After sterilization, the implant is able to be placed on the patient. The concept was developed using low cost technology and commercially available. The system has been tested in an in vivo hip arthroplasty performed on a sheep. The time increase of surgery was 80 minutes being 40 minutes the time of implant manufacturing. The system developed has been tested and the goals defined of the study achieved enabling the rapid manufacture of an implant in a time period compatible with the surgery time. PMID:27004181

  8. Rapid detection of bacteria in water (United States)

    Deininger, Rolf A.; Lee, Ji Y.


    A rapid detection of bacteria in water is essential for a timely response. This applies primarily to drinking water, be it bottled water or water from a public supply system, but is equally important for the analysis of water from swimming pools and beaches, and ballast water from oceangoing ships discharging into coastal or inland waters of the US. There are several methods available today for a rapid test including PCR based methods, flow cytometry, and electro chemiluminescence, to name a few. All of the above methods work, but are complicated and/or require expensive equipment and highly trained analysts in a laboratory. The method described here is based on lysing the bacteria after capture on a membrane filter, and measuring the ATP in a luminometer after the addition of luciferin/luciferase. This bioluminescence test can be done onsite, in less than 5 minutes, with equipment that fits onto a clipboard. It is a fast screening test that indicates if there is enough biologically active material in the same to pose a threat to the consumer. If this is the case, an additional step using immunomagnetic separation may be used to identify the responsible organisms. Tests have been done with E. coli 0157:H7, pseudomonas, and logionella. These tests take about 30 minutes each, and allow a quick determination of bacterial threats in a field situation.

  9. Rapid molecular detection of Lujo virus RNA. (United States)

    Atkinson, Barry; Chamberlain, John; Dowall, Stuart D; Cook, Nicola; Bruce, Christine; Hewson, Roger


    Lujo virus is an emerging arenavirus circulating in Southern Africa. Although to date there has only been a single outbreak of the novel haemorrhagic disease resulting from human infection with this virus, the case-fatality rate of exposed individuals, including nosocomial transmission, was 80%. The ability to identify viral haemorrhagic fevers accurately, especially those capable of nosocomial transmission, is of critical importance. Timely identification of these diseases allow medical professionals to isolate patients and implement barrier nursing techniques in order to prevent onward transmission of the virus. While rapid diagnostic methods are published for most viral haemorrhagic fevers, at present there are no such virus specific protocols for Lujo haemorrhagic fever. This report details the first set of diagnostic molecular assays designed to identify Lujo viral RNA rapidly, and demonstrates the potential functionality of these assays for use in the clinical setting. Although these assays have been designed and validated against a solitary isolate of Lujo virus, this represents the entirety of strains detected to date, and offer quick, cheap and easy methods for use in diagnostic laboratories.

  10. Ultra-Rapid Vision in Birds. (United States)

    Boström, Jannika E; Dimitrova, Marina; Canton, Cindy; Håstad, Olle; Qvarnström, Anna; Ödeen, Anders


    Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey.

  11. Rapid Detection of the Varicella Zoster Virus (United States)

    Lewis, Michelle P.; Harding, Robert


    1.Technology Description-Researchers discovered that when the Varicella Zoster Virus (VZV) reactivates from latency in the body, the virus is consistently present in saliva before the appearance of skin lesions. A small saliva sample is mixed with a specialized reagent in a test kit. If the virus is present in the saliva sample, the mixture turns a red color. The sensitivity and specificity emanates from an antibody-antigen reaction. This technology is a rapid, non-invasive, point of-of-care testing kit for detecting the virus from a saliva sample. The device is easy to use and can be used in clinics and in remote locations to quickly detect VZV and begin treatment with antiviral drugs. 2.Market Opportunity- RST Bioscience will be the first and only company to market a rapid, same day test kit for the detection of VZV in saliva. The RST detection test kit will have several advantages over existing, competitive technology. The test kit is self contained and laboratory equipment is not required for analysis of the sample. Only a single saliva sample is required to be taken instead of blood or cerebral spinal fluid. The test kit is portable, sterile and disposable after use. RST detection test kits require no electrical power or expensive storage equipment and can be used in remote locations. 3.Market Analysis- According to the CDC, it is estimated that 1 million cases of shingles occur each year in the U.S. with more than half over the age of sixty. There is a high demand for rapid diagnostics by the public. The point-of-care testing (POCT) market is growing faster than other segments of in vitro diagnostics. According to a July 2007 InteLab Corporation industry report the overall market for POCT was forecast to increase from $10.3 billion in 2005 to $18.7 billion by 2011. The market value of this test kit has not been determined. 4.Competition- The VZV vaccine prevents 50% of cases and reduces neuralgia by 66%. The most popular test detects VZV-specific IgM antibody


    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, S.


    A new method for the determination of radiostrontium in seawater samples has been developed at the Savannah River National Laboratory (SRNL) that allows rapid preconcentration and separation of strontium and yttrium isotopes in seawater samples for measurement. The new SRNL method employs a novel and effective pre-concentration step that utilizes a blend of calcium phosphate with iron hydroxide to collect both strontium and yttrium rapidly from the seawater matrix with enhanced chemical yields. The pre-concentration steps, in combination with rapid Sr Resin and DGA Resin cartridge separation options using vacuum box technology, allow seawater samples up to 10 liters to be analyzed. The total {sup 89}Sr + {sup 90}Sr activity may be determined by gas flow proportional counting and recounted after ingrowth of {sup 90}Y to differentiate {sup 89}Sr from {sup 90}Sr. Gas flow proportional counting provides a lower method detection limit than liquid scintillation or Cerenkov counting and allows simultaneous counting of samples. Simultaneous counting allows for longer count times and lower method detection limits without handling very large aliquots of seawater. Seawater samples up to 6 liters may be analyzed using Sr Resin for {sup 89}Sr and {sup 90}Sr with a Minimum Detectable Activity (MDA) of 1-10 mBq/L, depending on count times. Seawater samples up to 10 liters may be analyzed for {sup 90}Sr using a DGA Resin method via collection and purification of {sup 90}Y only. If {sup 89}Sr and other fission products are present, then {sup 91}Y (beta energy 1.55 MeV, 58.5 day half-life) is also likely to be present. {sup 91}Y interferes with attempts to collect {sup 90}Y directly from the seawater sample without initial purification of Sr isotopes first and {sup 90}Y ingrowth. The DGA Resin option can be used to determine {sup 90}Sr, and if {sup 91}Y is also present, an ingrowth option with using DGA Resin again to collect {sup 90}Y can be performed. An MDA for {sup 90}Sr of <1 m

  13. The Rapid Ice Sheet Change Observatory (RISCO) (United States)

    Morin, P.; Howat, I. M.; Ahn, Y.; Porter, C.; McFadden, E. M.


    The recent expansion of observational capacity from space has revealed dramatic, rapid changes in the Earth’s ice cover. These discoveries have fundamentally altered how scientists view ice-sheet change. Instead of just slow changes in snow accumulation and melting over centuries or millennia, important changes can occur in sudden events lasting only months, weeks, or even a single day. Our understanding of these short time- and space-scale processes, which hold important implications for future global sea level rise, has been impeded by the low temporal and spatial resolution, delayed sensor tasking, incomplete coverage, inaccessibility and/or high cost of data available to investigators. New cross-agency partnerships and data access policies provide the opportunity to dramatically improve the resolution of ice sheet observations by an order of magnitude, from timescales of months and distances of 10’s of meters, to days and meters or less. Advances in image processing technology also enable application of currently under-utilized datasets. The infrastructure for systematically gathering, processing, analyzing and distributing these data does not currently exist. Here we present the development of a multi-institutional, multi-platform observatory for rapid ice change with the ultimate objective of helping to elucidate the relevant timescales and processes of ice sheet dynamics and response to climate change. The Rapid Ice Sheet Observatory (RISCO) gathers observations of short time- and space-scale Cryosphere events and makes them easily accessible to investigators, media and general public. As opposed to existing data centers, which are structured to archive and distribute diverse types of raw data to end users with the specialized software and skills to analyze them, RISCO focuses on three types of geo-referenced raster (image) data products in a format immediately viewable with commonly available software. These three products are (1) sequences of images

  14. Rapid Parameterization Schemes for Aircraft Shape Optimization (United States)

    Li, Wu


    A rapid shape parameterization tool called PROTEUS is developed for aircraft shape optimization. This tool can be applied directly to any aircraft geometry that has been defined in PLOT3D format, with the restriction that each aircraft component must be defined by only one data block. PROTEUS has eight types of parameterization schemes: planform, wing surface, twist, body surface, body scaling, body camber line, shifting/scaling, and linear morphing. These parametric schemes can be applied to two types of components: wing-type surfaces (e.g., wing, canard, horizontal tail, vertical tail, and pylon) and body-type surfaces (e.g., fuselage, pod, and nacelle). These schemes permit the easy setup of commonly used shape modification methods, and each customized parametric scheme can be applied to the same type of component for any configuration. This paper explains the mathematics for these parametric schemes and uses two supersonic configurations to demonstrate the application of these schemes.

  15. Quadrupole magnet for a rapid cycling synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Witte, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States)


    Rapid Cycling Synchrotrons (RCS) feature interleaved warm and cold dipole magnets; the field of the warm magnets is used to modulate the average bending field depending on the particle energy. It has been shown that RCS can be an attractive option for fast acceleration of particles, for example, muons, which decay quickly. In previous studies it was demonstrated that in principle warm dipole magnets can be designed which can provide the required ramp rates, which are equivalent to frequencies of about 1 kHz. To reduce the losses it is beneficial to employ two separate materials for the yoke; it was also shown that by employing an optimized excitation coil geometry the eddy current losses are acceptable. In this paper we show that the same principles can be applied to quadrupole magnets targeting 30 T/m with a repetition rate of 1kHz and good field quality.

  16. Motion Analysis Based on Invertible Rapid Transform

    Directory of Open Access Journals (Sweden)

    J. Turan


    Full Text Available This paper presents the results of a study on the use of invertible rapid transform (IRT for the motion estimation in a sequence of images. Motion estimation algorithms based on the analysis of the matrix of states (produced in the IRT calculation are described. The new method was used experimentally to estimate crowd and traffic motion from the image data sequences captured at railway stations and at high ways in large cities. The motion vectors may be used to devise a polar plot (showing velocity magnitude and direction for moving objects where the dominant motion tendency can be seen. The experimental results of comparison of the new motion estimation methods with other well known block matching methods (full search, 2D-log, method based on conventional (cross correlation (CC function or phase correlation (PC function for application of crowd motion estimation are also presented.

  17. Methods and compositions for rapid thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher


    The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.

  18. Rapid induction of false memory for pictures. (United States)

    Weinstein, Yana; Shanks, David R


    Recognition of pictures is typically extremely accurate, and it is thus unclear whether the reconstructive nature of memory can yield substantial false recognition of highly individuated stimuli. A procedure for the rapid induction of false memories for distinctive colour photographs is proposed. Participants studied a set of object pictures followed by a list of words naming those objects, but embedded in the list were names of unseen objects. When subsequently shown full colour pictures of these unseen objects, participants consistently claimed that they had seen them, while discriminating with high accuracy between studied pictures and new pictures whose names did not appear in the misleading word list. These false memories can be reported with high confidence as well as the feeling of recollection. This new procedure allows the investigation of factors that influence false memory reports with ecologically valid stimuli and of the similarities and differences between true and false memories.

  19. Rapid Determination of Silicon Content in Rice

    Institute of Scientific and Technical Information of China (English)

    DAI Wei-min; ZHANG Ke-qin; DUAN Bin-wu; SUN Cheng-xiao; ZHENG Kang-le; CAI Run; ZHUANG Jie-yun


    A method for rapid determination of silicon content in rice was introduced. The reliability of this method was verified byusing a recombinant inbred line (RIL) population of rice cross Zhenshan 97B / Milyang 46. Two hundred and forty-nine RILs weretransplanted in two replications. Simple correlation coefficients on the silicon content in the hull, flag leaf and stem in rice betweenduplicate samples of 498 rice materials were 0.97954, 0.97026 and 0.98848, respectively. Ten representative samples wereselected for measurement using the high-temperature alkaline fusion method. Simple correlation coefficient between the siliconcontents determined by the high-temperature alkaline fusion method and by the present method is 0.9993.

  20. Metals Production Requirements for Rapid Photovoltaics Deployment

    CERN Document Server

    Kavlak, Goksin; Jaffe, Robert L; Trancik, Jessika E


    If global photovoltaics (PV) deployment grows rapidly, the required input materials need to be supplied at an increasing rate. In this paper, we quantify the effect of PV deployment levels on the scale of metals production. For example, we find that if cadmium telluride {copper indium gallium diselenide} PV accounts for more than 3% {10%} of electricity generation by 2030, the required growth rates for the production of indium and tellurium would exceed historically-observed production growth rates for a large set of metals. In contrast, even if crystalline silicon PV supplies all electricity in 2030, the required silicon production growth rate would fall within the historical range. More generally, this paper highlights possible constraints to the rate of scaling up metals production for some PV technologies, and outlines an approach to assessing projected metals growth requirements against an ensemble of past growth rates from across the metals production sector. The framework developed in this paper may be...

  1. Rapidly Moving Divertor Plates In A Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    S. Zweben


    It may be possible to replace conventional actively cooled tokamak divertor plates with a set of rapidly moving, passively cooled divertor plates on rails. These plates would absorb the plasma heat flux with their thermal inertia for ~10-30 sec, and would then be removed from the vessel for processing. When outside the tokamak, these plates could be cooled, cleaned, recoated, inspected, and then returned to the vessel in an automated loop. This scheme could provide nearoptimal divertor surfaces at all times, and avoid the need to stop machine operation for repair of damaged or eroded plates. We describe various possible divertor plate designs and access geometries, and discuss an initial design for a movable and removable divertor module for NSTX-U.

  2. Light Curves of Rapidly Rotating Neutron Stars

    CERN Document Server

    Braje, T M; Rauch, K P; Braje, Timothy M.; Romani, Roger W.; Rauch, Kevin P.


    We consider the effect of rapid rotation on the light curves of neutron stars with hot polar caps. For $P \\approx 3$ms spin periods, the pulse fractions can be as much as an order of magnitude larger than with simple slowly-rotating (Schwarzschild) estimates. Doppler boosting, in particular, leads to characteristic distortion and ``soft lags'' in the pulse profiles, which are easily measurable in light curves with moderate energy resolution. With $\\sim 10^5$ photons it should also be possible to isolate the more subtle distortions of light travel time variations and frame dragging. Detailed analysis of high quality millisecond pulsar data from upcoming X-ray missions must include these effects.

  3. The rapidly changing landscape of insect phylogenetics. (United States)

    Maddison, David R


    Insect phylogenetics is being profoundly changed by many innovations. Although rapid developments in genomics have center stage, key progress has been made in phenomics, field and museum science, digital databases and pipelines, analytical tools, and the culture of science. The importance of these methodological and cultural changes to the pace of inference of the hexapod Tree of Life is discussed. The innovations have the potential, when synthesized and mobilized in ways as yet unforeseen, to shine light on the million or more clades in insects, and infer their composition with confidence. There are many challenges to overcome before insects can enter the 'phylocognisant age', but because of the promise of genomics, phenomics, and informatics, that is now an imaginable future.

  4. Fetal magnetocardiography: Methods for rapid data reduction (United States)

    Mosher, John C.; Flynn, Edward R.; Quinn, A.; Weir, A.; Shahani, U.; Bain, R. J. P.; Maas, P.; Donaldson, G. B.


    Fetal magnetocardigraphy (fMCG) provides a unique method for noninvasive observations of the fetal heart. Electrical currents generated by excitable tissues within the fetal heart yield measurable external magnetic fields. Measurements are performed with superconducting quantum interference devices inductively coupled to magnetometer or gradiometer coils, and the resulting signals are converted to digital form in the data acquisition system. The measured fields are usually contaminated by fetal and maternal movements (usually respiration), other physiological fields such as skeletal muscle contraction, the maternal cardiac signal, and environmental electromagnetic fields. Sensitivity to relatively distant sources, both physiological and environmental, is substantially reduced by the use of magnetic gradiometers. Other contaminants may be removed by proper signal conditioning which may be automatically applied using "black box" algorithms that are transparent to the user and highly efficient. These procedures can rapidly reduce the complex signal plus noise waveforms to the desired fMCG with minimal operator interference.

  5. Neural Networks for Rapid Design and Analysis (United States)

    Sparks, Dean W., Jr.; Maghami, Peiman G.


    Artificial neural networks have been employed for rapid and efficient dynamics and control analysis of flexible systems. Specifically, feedforward neural networks are designed to approximate nonlinear dynamic components over prescribed input ranges, and are used in simulations as a means to speed up the overall time response analysis process. To capture the recursive nature of dynamic components with artificial neural networks, recurrent networks, which use state feedback with the appropriate number of time delays, as inputs to the networks, are employed. Once properly trained, neural networks can give very good approximations to nonlinear dynamic components, and by their judicious use in simulations, allow the analyst the potential to speed up the analysis process considerably. To illustrate this potential speed up, an existing simulation model of a spacecraft reaction wheel system is executed, first conventionally, and then with an artificial neural network in place.

  6. China's Wind Power in Rapid Progressing

    Institute of Scientific and Technical Information of China (English)


    China's wind power has gone through an exploring course of 20years. At present, it is on the fast track under the support of the state's preferential policies concerned. The various wind power development areas in China have made rapid progress and put forward their own thinking of developing wind energy.%经过20年的探索和发展,中国风电在国家相关优惠政策的支持下,现已走上了快速发展的道路。各个风电开发地区已经取得了长足的进步,并各自提出了今后发展风电的设想。

  7. Rapid variability of extragalactic radio sources

    Energy Technology Data Exchange (ETDEWEB)

    Quirrenbach, A.; Witzel, A.; Krichbaum, T.; Hummel, C.A.; Alberdi, A.; Schalinski, C.


    Since its discovery more than 20 years ago, variability of extragalactic radio sources on timescales of weeks to years has been the subject of many investigations. We have examined the variability of these sources on timescales of hours at wavelengths of 6 and 11 cm using the 100-m telescope of the Max-Planck-Institut fuer Radioastronomie and report the results for two sources. The quasar QSO0917 + 62 showed variations with amplitudes of up to 23% in /similar to/ 24 hours, which were correlated at the two wavelengths; in the BL Lac object 0716 + 71 we found variations with amplitudes of 7-11%. We discuss intrinsic effects, gravitational lensing and scattering in the interstellar medium as possible explanations for rapid radio variability.

  8. Methods and compositions for rapid thermal cycling (United States)

    Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher


    The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.

  9. Rapid deployable global sensing hazard alert system

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph V; Tibrea, Steven L; Shull, Davis J; Coleman, Jerry T; Shuler, James M


    A rapid deployable global sensing hazard alert system and associated methods of operation are provided. An exemplary system includes a central command, a wireless backhaul network, and a remote monitoring unit. The remote monitoring unit can include a positioning system configured to determine a position of the remote monitoring unit based on one or more signals received from one or more satellites located in Low Earth Orbit. The wireless backhaul network can provide bidirectional communication capability independent of cellular telecommunication networks and the Internet. An exemplary method includes instructing at least one of a plurality of remote monitoring units to provide an alert based at least in part on a location of a hazard and a plurality of positions respectively associated with the plurality of remote monitoring units.

  10. The application of rapid prototyping in prosthodontics. (United States)

    Sun, Jian; Zhang, Fu-Qiang


    Dentists have used rapid prototyping (RP) techniques in the fields of oral maxillofacial surgery simulation and implantology. With new research emerging for molding materials and the forming process of RP techniques, this method is becoming more attractive in dental prosthesis fabrication; however, few researchers have published material on the RP technology of prosthesis pattern fabrication. This article reviews and discusses the application of RP techniques for prosthodontics including: (1) fabrication of wax pattern for the dental prosthesis, (2) dental (facial) prosthesis mold (shell) fabrication, (3) dental metal prosthesis fabrication, and (4) zirconia prosthesis fabrication. Many people could benefit from this new technology through various forms of dental prosthesis production. Traditional prosthodontic practices could also be changed by RP techniques in the near future.

  11. Rapid bioassay for oil-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Ashworth, J. [ALS Environmental, Edmonton, AB (Canada); Oosterbroek, L. [HydroQual, Calgary, AB (Canada)


    This PowerPoint presentation described a study conducted to develop a rapid bioassay for soils contaminated with oil. The bioassay method was designed for a weight of evidence (WoE) approach and eco-contact guideline derivation protocol. Microtox bioassays were conducted on cyclodextrin extracts of soil quantified by solvent extraction and gas chromatography. The method was demonstrated using straight {beta}-cyclodextrin soil extracts and activated {beta}-cyclodextrin soil extracts. An analysis of the methods showed that the activation step weakens or breaks the cyclodextrin and polycyclic hydrocarbon (PHC) inclusion complex. The released PHC became toxic to the microtox organism. Results from the bioassays were then correlated with earthworm reproduction bioassay results. tabs., figs.

  12. Embryo culture and rapid propagation of Syringa

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li; DAI Li-min; SU Bao-ling


    Embryo of lilacs (Syringa L) culture in vitro and the rapid propagation were studied. The orthogonal experiments, including the selection of basal medium, embryo age and other factors such as sugar, benzyladenine (BA), naphthalene acetic acid (NAA) and glutamine (Gln), were carried out. The results indicated that the optimal medium for embryo culture was Monnier medium supplemented with NAA (0.001 mg@L-1), BA (0.1 mg@L-1), sugar (50 g@L-1), and Gln (400 mg@L-1), with a germination rate of 91.7% at least; the optimal embryo age was 50 d; and Gln had significant effects on the germination rate of embryo. Moreover, the optimal medium for subculture was MS+BA (2 mg@L-1)+NAA (0.001 mg@L-1)+Gln (0.5 mg@L-1), with the propagation coefficient of 3.6 at least.

  13. Rapid adiabatic passage without level crossing

    CERN Document Server

    Rangelov, A A; Shore, B W


    We present a method for achieving complete population transfer in a two-state quantum system via adiabatic time evolution in which, contrary to conventional rapid adiabatic passage produced by chirped pulses, there occurs no crossing of diabatic energy curves: there is no sign change of the detuning. Instead, we use structured pulses, in which, in addition to satisfying conditions for adiabatic evolution, there occurs a sign change of the Rabi frequency when the detuning is zero. We present simulations that offer simple geometrical interpretation of the two-dimensional motion of the Bloch vector for this system, illustrating how both complete population inversion and complete population return occur for different choices of structured pulses.

  14. Rapid surface sampling and archival record system

    Energy Technology Data Exchange (ETDEWEB)

    Barren, E.; Penney, C.M.; Sheldon, R.B. [GE Corporate Research and Development Center, Schenectady, NY (United States)] [and others


    A number of contamination sites exist in this country where the area and volume of material to be remediated is very large, approaching or exceeding 10{sup 6} m{sup 2} and 10{sup 6} m{sup 3}. Typically, only a small fraction of this material is actually contaminated. In such cases there is a strong economic motivation to test the material with a sufficient density of measurements to identify which portions are uncontaminated, so extensively they be left in place or be disposed of as uncontaminated waste. Unfortunately, since contamination often varies rapidly from position to position, this procedure can involve upwards of one million measurements per site. The situation is complicated further in many cases by the difficulties of sampling porous surfaces, such as concrete. This report describes a method for sampling concretes in which an immediate distinction can be made between contaminated and uncontaminated surfaces. Sample acquisition and analysis will be automated.

  15. Rapid virtual stenting for intracranial aneurysms (United States)

    Zhao, Liang; Chen, Danyang; Chen, Zihe; Wang, Xiangyu; Paliwal, Nikhil; Xiang, Jianping; Meng, Hui; Corso, Jason J.; Xu, Jinhui


    The rupture of Intracranial Aneurysms is the most severe form of stroke with high rates of mortality and disability. One of its primary treatments is to use stent or Flow Diverter to divert the blood flow away from the IA in a minimal invasive manner. To optimize such treatments, it is desirable to provide an automatic tool for virtual stenting before its actual implantation. In this paper, we propose a novel method, called ball-sweeping, for rapid virtual stenting. Our method sweeps a maximum inscribed sphere through the aneurysmal region of the vessel and directly generates a stent surface touching the vessel wall without needing to iteratively grow a deformable stent surface. Our resulting stent mesh has guaranteed smoothness and variable pore density to achieve an enhanced occlusion performance. Comparing to existing methods, our technique is computationally much more efficient.

  16. Rapid thermal anneal of arsenic implanted silicon

    Energy Technology Data Exchange (ETDEWEB)

    Feygenson, A.


    The distribution of arsenic implanted into silicon during rapid thermal anneal (RTA) was investigated. Secondary ion mass spectrometry, Rutherford backscattering spectrometry, and channeling techniques were used for the measurement of the total (chemical) dopant profile. The electrically active dopant profiles were measured with sheet resistance, sheet-resistance maps, spreading resistance and pinch resistors. It was found that arsenic profile after RTA is influenced by many parameters including crystallographic orientation of the sample, temperature gradient, and defect structure in the surface part affected by heavy arsenic implant. A diffusion model based on inhomogeneous medium was examined. Exact solutions of the diffusion equation were obtained for the rectangular and Gaussian initial dopant profiles. Calculated results are compared to the measured profiles. It is concluded that model satisfactory predicts the major features of the arsenic diffusion into silicon during RTA.

  17. Rapid Thermal Anneal of Arsenic Implanted Silicon. (United States)

    Feygenson, Anatoly


    The distribution of arsenic implanted into silicon during rapid thermal anneal (RTA) has been investigated. Secondary ion mass spectrometry (SIMS), Rutherford backscattering spectrometry (RBS) and channeling techniques were used for the measurement of the total (chemical) dopant profile. The electrically active dopant profiles were measured with sheet resistance, sheet resistance maps, spreading resistance, and pinch resistors. It has been found that arsenic profile after RTA is influenced by many parameters including crystallographic orientation of the sample, temperature gradient, and defect structure in the surface part affected by heavy arsenic implant. A diffusion model based on inhomogeneous medium was examined. Exact solutions of the diffusion equation were obtained for the rectangular and Gaussian initial dopant profiles. Calculated results are compared to the measured profiles. It is concluded that model satisfactory predicts the major features of the arsenic diffusion into silicon during RTA.

  18. Design of a rapidly cooled cryogenic mirror (United States)

    Plummer, Ron; Hsu, Ike


    The paper discusses the design, analysis, and testing of a rapidly cooled beryllium cryogenic mirror, which is the primary mirror in the four-element optical system for the Long Wavelength Infrared Advanced Technology Seeker. The mirror is shown to meet the requirement of five minutes for cooling to cryogenic operating temperature; it also maintains its optical figure and vacuum integrity and meets the nuclear specification. Results of a detailed thermal analysis on the mirror showed that, using nitrogen gas at 80 K as coolant, the front face of the mirror can be cooled from an initial temperature of 300 K to less than 90 K within five minutes. In a vacuum chamber, using liquid nitrogen as coolant, the mirror can be cooled to 80 K within 1.5 min. The mirror is well thermally insulated, so that it can be maintained at less than its operating temperature for a long time without active cooling.

  19. Mass Spectrometry for Rapid Characterization of Microorganisms (United States)

    Demirev, Plamen A.; Fenselau, Catherine


    Advances in instrumentation, proteomics, and bioinformatics have contributed to the successful applications of mass spectrometry (MS) for detection, identification, and classification of microorganisms. These MS applications are based on the detection of organism-specific biomarker molecules, which allow differentiation between organisms to be made. Intact proteins, their proteolytic peptides, and nonribosomal peptides have been successfully utilized as biomarkers. Sequence-specific fragments for biomarkers are generated by tandem MS of intact proteins or proteolytic peptides, obtained after, for instance, microwave-assisted acid hydrolysis. In combination with proteome database searching, individual biomarker proteins are unambiguously identified from their tandem mass spectra, and from there the source microorganism is also identified. Such top-down or bottom-up proteomics approaches permit rapid, sensitive, and confident characterization of individual microorganisms in mixtures and are reviewed here. Examples of MS-based functional assays for detection of targeted microorganisms, e.g., Bacillus anthracis, in environmental or clinically relevant backgrounds are also reviewed.

  20. Coral reef evolution on rapidly subsiding margins (United States)

    Webster, J.M.; Braga, J.C.; Clague, D.A.; Gallup, C.; Hein, J.R.; Potts, D.C.; Renema, W.; Riding, R.; Riker-Coleman, K.; Silver, E.; Wallace, L.M.


    A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2-6??m/ka) over the last 500??ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20??ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100-500??ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate

  1. Rapid toxicity screening of gasification ashes. (United States)

    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


    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=0.05IC50, 24hIC50, 24h

  2. Sensitive, Rapid Detection of Bacterial Spores (United States)

    Kern, Roger G.; Venkateswaran, Kasthuri; Chen, Fei; Pickett, Molly; Matsuyama, Asahi


    A method of sensitive detection of bacterial spores within delays of no more than a few hours has been developed to provide an alternative to a prior three-day NASA standard culture-based assay. A capability for relatively rapid detection of bacterial spores would be beneficial for many endeavors, a few examples being agriculture, medicine, public health, defense against biowarfare, water supply, sanitation, hygiene, and the food-packaging and medical-equipment industries. The method involves the use of a commercial rapid microbial detection system (RMDS) that utilizes a combination of membrane filtration, adenosine triphosphate (ATP) bioluminescence chemistry, and analysis of luminescence images detected by a charge-coupled-device camera. This RMDS has been demonstrated to be highly sensitive in enumerating microbes (it can detect as little as one colony-forming unit per sample) and has been found to yield data in excellent correlation with those of culture-based methods. What makes the present method necessary is that the specific RMDS and the original protocols for its use are not designed for discriminating between bacterial spores and other microbes. In this method, a heat-shock procedure is added prior to an incubation procedure that is specified in the original RMDS protocols. In this heat-shock procedure (which was also described in a prior NASA Tech Briefs article on enumerating sporeforming bacteria), a sample is exposed to a temperature of 80 C for 15 minutes. Spores can survive the heat shock, but nonspore- forming bacteria and spore-forming bacteria that are not in spore form cannot survive. Therefore, any colonies that grow during incubation after the heat shock are deemed to have originated as spores.

  3. Diamond grooving of rapidly solidified optical aluminium (United States)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima


    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  4. Framework for Bus Rapid Transit Development and Deployment Planning


    Miller, Mark A.; Yin, Yafeng; Balvanyos, Tunde; Ceder, Avishai


    This report presents the results of its investigation into deployment planning for bus rapid transit systems. In this study, we conducted a macro-scale examination of bus rapid transit systems from technical, operational, institutional, and planning perspectives. We then developed the theoretical foundation for a deployment planning framework for bus rapid transit systems that specifically takes into account the unique features of bus rapid transit that differ from other transit alternatives....

  5. Economic Growth——"Sound and Rapid" Development

    Institute of Scientific and Technical Information of China (English)



    Sound and rapid development is an intrinsic requirement in the implementation of the "scientific outlook on development" and represents an important change in the concept of economic development. This article, reviews past achievements under the guidance of "rapid and sound" development, and brings to light the reasons why we need to pursue "sound and rapid" development and how it can be achieved.

  6. Rapid E-Learning Simulation Training and User Response (United States)

    Rackler, Angeline


    A new trend in e-learning development is to have subject matter experts use rapid development tools to create training simulations. This type of training is called rapid e-learning simulation training. Though companies are using rapid development tools to create training quickly and cost effectively, there is little empirical research to indicate…

  7. Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease (United States)

    Wong, Min Ney; Murdoch, Bruce E.; Whelan, Brooke-Mai


    Background: Rapid syllable repetition tasks are commonly used in the assessment of motor speech disorders. However, little is known about the articulatory kinematics during rapid syllable repetition in individuals with Parkinson's disease (PD). Aims: To investigate and compare lingual kinematics during rapid syllable repetition in dysarthric…

  8. Urban flood risk warning under rapid urbanization. (United States)

    Chen, Yangbo; Zhou, Haolan; Zhang, Hui; Du, Guoming; Zhou, Jinhui


    In the past decades, China has observed rapid urbanization, the nation's urban population reached 50% in 2000, and is still in steady increase. Rapid urbanization in China has an adverse impact on urban hydrological processes, particularly in increasing the urban flood risks and causing serious urban flooding losses. Urban flooding also increases health risks such as causing epidemic disease break out, polluting drinking water and damaging the living environment. In the highly urbanized area, non-engineering measurement is the main way for managing urban flood risk, such as flood risk warning. There is no mature method and pilot study for urban flood risk warning, the purpose of this study is to propose the urban flood risk warning method for the rapidly urbanized Chinese cities. This paper first presented an urban flood forecasting model, which produces urban flood inundation index for urban flood risk warning. The model has 5 modules. The drainage system and grid dividing module divides the whole city terrain into drainage systems according to its first-order river system, and delineates the drainage system into grids based on the spatial structure with irregular gridding technique; the precipitation assimilation module assimilates precipitation for every grids which is used as the model input, which could either be the radar based precipitation estimation or interpolated one from rain gauges; runoff production module classifies the surface into pervious and impervious surface, and employs different methods to calculate the runoff respectively; surface runoff routing module routes the surface runoff and determines the inundation index. The routing on surface grid is calculated according to the two dimensional shallow water unsteady flow algorithm, the routing on land channel and special channel is calculated according to the one dimensional unsteady flow algorithm. This paper then proposed the urban flood risk warning method that is called DPSIR model based

  9. Comparison of rapid-cycling and non-rapid-cycling bipolar disorder based on prospective mood ratings in 539 outpatients

    NARCIS (Netherlands)

    Kupka, RW; Luckenbaugh, DA; Post, RM; Suppes, T; Altshuler, LL; Keck, PE; Frye, MA; Denicoff, KD; Grunze, H; Leverich, GS; McElroy, SL; Walden, J; Nolen, WA


    Objective: To detect risk factors for rapid cycling in bipolar disorder, the authors compared characteristics of rapid-cycling and non-rapid-cycling patients both from a categorical and a dimensional perspective. Method: Outpatients with bipolar I disorder (N = 419), bipolar II disorder (N = 104), a

  10. Rapid Map Updating Procedures Using Orthophotos (United States)

    Alrajhi, M.


    The General Directorate of Surveying and Mapping (GDSM) of the Ministry for Municipal and Rural Affairs (MOMRA) of the Kingdom of Saudi Arabia has the mandate for large scale mapping of 220 Saudi Arabian cities. During the last 30 years all of these cities have been mapped in 3D at least once using stereo photogrammetric procedures. The output of these maps is in digital vector files with more than 300 types of features coded. Mapping at the required scales of 1:10,000 for the urban and suburban areas and at 1:1,000 for the urban areas proper has been a lengthy and costly process, which did not lend itself to regular updating procedures. For this reason the major cities, where most of the developments took place, have been newly mapped at about 10 year intervals. To record the changes of urban landscapes more rapidly orthophotomapping has recently been introduced. Rather than waiting for about 5 years for the line mapping of a large city after the inception of a mapping project, orthophotos could be produced a few months after a new aerial flight was made. While new, but slow stereomapping in 3D provides accurate results in conformity with the usual urban mapping specifications, the geocoded superposition of outdated maps with the more recent orthophotos provided a very useful monitoring of the urban changes. At the same time the use of orthophotos opens up a new possibility for urban map updating by on-screen digitizing in 2D. This can at least be done for the most relevant features, such as buildings, walls, roads and vegetation. As this is a faster method than 3D stereo plotting a lesser geometric accuracy is to be expected for the on-screen digitization. There is a need to investigate and to compare the two methods with respect to accuracy and speed of operation as a basis for a decision, whether to continue with new 3D stereomapping every 10 years or to introduce rapid map updating in 2D via on-screen digitization every 3 to 5 years. This presentation is about

  11. Rapid world modelling from a mobile platform

    Energy Technology Data Exchange (ETDEWEB)

    Barry, R.E.; Jones, J.P. [Oak Ridge National Lab., TN (United States); Little, C.Q. [Sandia National Labs., Albuquerque, NM (United States); Wilson, C.W.


    The ability to successfully use and interact with a computerized world model is dependent on the ability to create an accurate world model. The goal of this project was to develop a prototype system to remotely deploy sensors into a workspace, collect surface information, and rapidly build an accurate world model of that workspace. A key consideration was that the workspace areas are typically hazardous environments, where it is difficult or impossible for humans to enter. Therefore, the system needed to be fully remote, with no external connections. To accomplish this goal, an electric, mobile platform with battery power sufficient for both the platform and sensor electronics was procured and 3D range sensors were deployed on the platform to capture surface data within the workspace. A radio Ethernet connection was used to provide communications to the vehicle and all on-board electronics. Video from on-board cameras was also transmitted to the base station and used to teleoperate the vehicle. Range data generated by the on-board 3D sensors was transformed into surface maps, or models. Registering the sensor location to a consistent reference frame as the platform moved through the workspace allowed construction of a detailed 3D world model of the extended workspace.

  12. A Rapid Process for Fabricating Gas Sensors

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao


    Full Text Available Zinc oxide (ZnO is a low-toxicity and environmentally-friendly material applied on devices, sensors or actuators for “green” usage. A porous ZnO film deposited by a rapid process of aerosol deposition (AD was employed as the gas-sensitive material in a CO gas sensor to reduce both manufacturing cost and time, and to further extend the AD application for a large-scale production. The relative resistance change (△R/R of the ZnO gas sensor was used for gas measurement. The fabricated ZnO gas sensors were measured with operating temperatures ranging from 110 °C to 180 °C, and CO concentrations ranging from 100 ppm to 1000 ppm. The sensitivity and the response time presented good performance at increasing operating temperatures and CO concentrations. AD was successfully for applied for making ZnO gas sensors with great potential for achieving high deposition rates at low deposition temperatures, large-scale production and low cost.

  13. Rapid Diagnosis of Chlamydial Conjunctivitis in Laboratory

    Institute of Scientific and Technical Information of China (English)

    LiuJX; LiYP


    Purpose:To evaluate the techniques of rapid and accurate diagnosis of chlamydial conjunctivitis.Methods:Total 100 conjunctivitis patients(200 eyes) were studied.Twenty-tw of 100 cases were diagnosed as chlamydial conjunctivitis.The infected epithelia were scraped from tarsal conjunctive of both eyes and stained separately with Giemsa(100 cases)and immunofluorescnce (anti-chlamydial antigen monoclonal antibody,100 cases)Result:In immunofluorescent staining,38 cases were seen positive staining and 62 were negative.In giemsa staining,29 were positive,and 71 were negative.In 22 cases with clinical diagnosis of chlamydial conjunctivitis,13 cases were confirmed,and 9 were excluded by immunofluorescent staining,Technically,immunofluorescent and Gemsa stain takes 45 and 40 minutes,respectively.Conclusion:Comparing to Giemsa stain,38 of 100 scraping specimens were positive (38%) by immunofluorescent stainign,29 of 100 per cent were psitive by Giemsa staining,Giemsa staining takes 5 minutes less than immunofluorescent stainign (40 versus 45 minutes),however,the positive staining in immunofluorescent staining is much easier to be recognized than Giemsa staining.

  14. Facing Two Rapidly Spreading Internet Worms

    CERN Multimedia

    IT Department


    The Internet is currently facing a growing number of computer infections due to two rapidly spreading worms. The "Conficker" and "Downadup" worms have infected an estimated 1.1 million PCs in a 24-hour period, bringing the total number of infected computers to 3.5 million [1]. Via a single USB stick, these worms were also responsible for the infection of about 40 laptops at the last EGEE conference in Istanbul. In order to reduce the impact of these worms on CERN Windows computers, the Computer Security Team has suggested several preventive measures described here. Disabling the Windows AutoRun and AutoPlay Features The Computer Security Team and the IT/IS group have decided to disable the "AutoRun" and "AutoPlay" functionality on all centrally-managed Windows computers at CERN. When inserting CDs, DVDs or USB sticks into a PC, "AutoRun" and "AutoPlay" are responsible for automatically playing music or films stored on these media, or ...

  15. Gravitational waves from rapidly rotating neutron stars

    CERN Document Server

    Haskell, Brynmor; D`Angelo, Caroline; Degenaar, Nathalie; Glampedakis, Kostas; Ho, Wynn C G; Lasky, Paul D; Melatos, Andrew; Oppenoorth, Manuel; Patruno, Alessandro; Priymak, Maxim


    Rapidly rotating neutron stars in Low Mass X-ray Binaries have been proposed as an interesting source of gravitational waves. In this chapter we present estimates of the gravitational wave emission for various scenarios, given the (electromagnetically) observed characteristics of these systems. First of all we focus on the r-mode instability and show that a 'minimal' neutron star model (which does not incorporate exotica in the core, dynamically important magnetic fields or superfluid degrees of freedom), is not consistent with observations. We then present estimates of both thermally induced and magnetically sustained mountains in the crust. In general magnetic mountains are likely to be detectable only if the buried magnetic field of the star is of the order of $B\\approx 10^{12}$ G. In the thermal mountain case we find that gravitational wave emission from persistent systems may be detected by ground based interferometers. Finally we re-asses the idea that gravitational wave emission may be balancing the ac...

  16. Rapidly evolving microorganisms with high biofuel tolerance (United States)

    Vyawahare, Saurabh; Zhang, Qiucen; Lang, Wendy; Austin, Robert


    Replacing non-renewable energy sources is one of the biggest and most exciting challenges of our generation. Algae and bacteria are poised to become major renewable biofuels if strains can be developed that provide a high,consistent and robust yield of oil. One major stumbling block towards this goal is the lack of tolerance to high concentrations of biofuels like isobutanol. Using traditional bioengineering techniques to remedy this face the hurdle of identifying the correct pathway or gene to modify. But the multiplicity of interactions inside a cell makes it very hard to determine what to modify a priori. Instead, we propose a technology that does not require prior knowledge of the genes or pathways to modify. In our approach that marries microfabrication and ecology, spatial heterogeneity is used as a knob to speed up evolution in the desired direction. Recently, we have successfully used this approach to demonstrate the rapid emergence of bacterial antibiotic resistance in as little as ten hours. Here, we describe our experimental results in developing new strains of micro-organisms with high oil tolerance. Besides biofuel production, our work is also relevant to oil spill clean-ups.

  17. Rapid Measurement of Nanoparticle Thickness Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Katz-Boon, Hadas, E-mail: [Department of Materials Engineering, Monash University, VIC 3800 (Australia); Rossouw, Chris J. [Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia); Dwyer, Christian; Etheridge, Joanne [Department of Materials Engineering, Monash University, VIC 3800 (Australia); Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia)


    A method to measure the thickness of a single-crystal nanoparticle in the direction parallel to the incident beam from annular dark field scanning transmission electron microscope (ADF-STEM) images is reported, providing a map of thickness versus position across the nanoparticle-a 'thickness profile' image. The method is rapid and hence suitable for surveying large numbers of nanoparticles. The method measures the intensity scattered to a characterised ADF detector and compares this to the incident beam intensity, to obtain a normalized ADF image. The normalised intensity is then converted to thickness via dynamical ADF image simulations. The method is accurate within 10% and the precision is dominated primarily by 'shot noise'. Merits and limitations of this method are discussed. A method to calibrate the response function of the ADF detector without external equipment is also described, which is applicable to the entire range of gain and background settings. -- Highlights: Black-Right-Pointing-Pointer A method is developed to convert ADF-STEM images to 'thickness profile' images. Black-Right-Pointing-Pointer It is applicable in particles survey, facets determination and discrete tomography. Black-Right-Pointing-Pointer A method to calibrate the response of the ADF detector is described. Black-Right-Pointing-Pointer The response in analysed across a range of conditions. Black-Right-Pointing-Pointer Dynamical ADF image simulations are presented, demonstrating intensity vs. thickness dependence.

  18. Conjugated polymer composite nanoparticles by rapid mixing. (United States)

    Jung, Christoph; de Roo, Tjaard; Mecking, Stefan


    Composite nanoparticles from poly[(9,9-di-n-octylfluoren-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT) and poly(9,9-di-n-hexylfluoren-2,7-diyl) (PF) with embedded inorganic nanoparticles (TiO2 , CdSe, and CdSe/CdS) are prepared through kinetic trapping by rapid turbulent mixing in a multi-inlet vortex mixer without the need for polymer functionalization. High contents of inorganic materials up to 50-60 wt% are realized for all composites. The influence of flow ratios, sodium dodecyl sulfate (SDS) concentration, and absolute flow rates on the particle size and morphology is studied. High water-to-THF ratios and high total flow rates around 2 m s(-1) yield particle sizes below 50 nm. By adjusting these parameters, controlled particle sizes between 30 to several hundred nanometers are obtained. Composite particles from CdSe/CdS and F8BT or PF show a strong quenching of the polymer emission and near exclusive emission from the inorganic nanocrystal, which indicates an efficient energy transfer with fluorescence quantum yields of 23% for the F8BT/CdSe/CdS composites and 21% for the PF/CdSe/CdS composites. The dispersions are colloidally stable for several months.

  19. Advanced FBG sensing through rapid spectral interrogation (United States)

    Kunzler, Wesley; Newman, Jason; Wilding, Daniel; Zhu, Zixu; Lowder, Tyson; Selfridge, Richard; Schultz, Stephen; Wirthlin, Michael


    A fiber Brag grating sensor interrogator has been developed which is capable of gathering vectors of information from individual fiber Bragg gratings by capturing the full optical spectrum 3 kHz. Using a field programmable gate array with high speed digital-to-analog converters and analog-to-digital components, plus a kilohertz rate MEMS optical filter, the optical spectrum can be scanned at rates in excess of 10 million nanometers per second, allowing sensor sampling rates of many kilohertz while maintaining the necessary resolution to understand sensor changes. The autonomous system design performs all necessary detection and processing of multiple sensors and allows spectral measurements to be exported as fast as Ethernet, USB, or RS232 devices can receive it through a memory mapped interface. The high speed - full spectrum - fiber Bragg grating sensor interrogator enables advanced interrogation of dynamic strain and temperature gradients along the length of a sensor, as well as the use of each sensor for multiple stimuli, such as in temperature compensation. Two examples are described, showing interrogation of rapid laser heating in an optical fiber, as well as complex strain effects in a beam that had an engineered defect.

  20. Heliopause Electrostatic Rapid Transit System (HERTS) (United States)

    Wiegmann, Bruce M.


    A recent six month investigation focused on: "Determining the benefits of propelling a scientific spacecraft by an 'Electric Sail' propulsion system to the edge of our solar system (the Heliopause), a distance of 100 to 120 AU, in ten years or less" has recently been completed by the Advance Concepts Office at NASA's MSFC. The concept investigated has been named the Heliopause Electrostatic Rapid Transit System (HERTS) by the MSFC team. The HERTS is a revolutionary propellant-less propulsion concept that is ideal for deep space missions to the Outer Planets, Heliopause, and beyond. It is unique in that it uses momentum exchange from naturally occurring solar wind protons to propel a spacecraft within the heliosphere. The propulsion system consists of an array of electrically positively-biased wires that extend outward 20 km from a rotating (one revolution per hour) spacecraft. It was determined that the HERTS system can accelerate a spacecraft to velocities as much as two to three times that possible by any realistic extrapolation of current state-of-the-art propulsion technologies- including solar electric and solar sail propulsion systems. The data produced show that a scientific spacecraft could reach distances of 100AU in less than 10 years. Moreover, it can be reasonably expected that this system could be developed within a decade and provide meaningful Heliophysics Science and Outer Planetary Science returns in the 2025-2035 timeframe.